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Hinton RGK, Macleod CJA, Troldborg M, Kanjaye MB, Kalin RM. The Status of Sanitation in Malawi: Is SDG6.2 Achievable? Int J Environ Res Public Health 2023; 20:6528. [PMID: 37569068 PMCID: PMC10418781 DOI: 10.3390/ijerph20156528] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2023] [Revised: 07/15/2023] [Accepted: 07/27/2023] [Indexed: 08/13/2023]
Abstract
Ensuring access to adequate and equitable sanitation and ending open defecation by 2030 is the focus of Sustainable Development Goal 6.2 (SDG6.2). We evaluated Malawi's progress towards SDG 6.2 (specifically the goal to end open defecation), presenting the results of a national survey of over 200,000 sanitary facilities and evaluating their management. Based on non-linear population dynamics, we used a linear model to evaluate the reduction in open defecation between 1992-2018, and to project whether Malawi can meet the SDG target to end open defecation by 2030 under multiple scenarios of population growth. Whilst Malawi has made considerable progress in providing sanitary provision for the population, we estimate that, at the current rate of the provision of sanitary facilities, Malawi will not reach SDG 6.2 by 2030 under any of the modelled socioeconomic scenarios. Furthermore, we compare the estimates of the extent of sanitary provision classed as improved from multiple surveys, including the USAID Demographic and Health (DHS) Surveys and Government of Malawi Census data. We conclude that some of the surveys (particularly the 2015/16 DHS) may be overestimating the level of improved sanitary provision, and we hypothesize that this is due to how pit-latrines with earth/sand slabs are classed. Furthermore, we examine the long-term sustainability of pit-latrine use, investigating the challenge of pit-latrine abandonment and identifying pit-latrine filling as a cause of the abandonment in 30.2% of cases. We estimate that between 2020-2070, 31.8 (range 2.8 to 3320) million pit-latrines will be filled and abandoned, representing a major challenge for the safe management of abandoned latrines, a potential for long-term impacts on the groundwater quality, and a significant loss of investment in sanitary infrastructure. For Malawi to reach SDG 6.2, improvements are needed in both the quantity and quality of its sanitary facilities.
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Affiliation(s)
- Rebekah G. K. Hinton
- Department of Civil and Environmental Engineering, University of Strathclyde, Glasgow G1 1XJ, UK
- The James Hutton Institute, Craigiebuckler, Aberdeen AB15 8QH, UK
| | | | - Mads Troldborg
- The James Hutton Institute, Craigiebuckler, Aberdeen AB15 8QH, UK
| | - Modesta B. Kanjaye
- Ministry of Water and Sanitation, Government of Malawi, Private Bag 390, Lilongwe, Malawi
| | - Robert M. Kalin
- Department of Civil and Environmental Engineering, University of Strathclyde, Glasgow G1 1XJ, UK
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2
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Rivett MO, Tremblay-Levesque LC, Carter R, Thetard RCH, Tengatenga M, Phoya A, Mbalame E, Mchilikizo E, Kumwenda S, Mleta P, Addison MJ, Kalin RM. Acute health risks to community hand-pumped groundwater supplies following Cyclone Idai flooding. Sci Total Environ 2022; 806:150598. [PMID: 34597537 DOI: 10.1016/j.scitotenv.2021.150598] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2021] [Revised: 09/07/2021] [Accepted: 09/22/2021] [Indexed: 06/13/2023]
Abstract
This longitudinal flood-relief study assessed the impact of the March 2019 Cyclone Idai flood event on E. coli contamination of hand-pumped boreholes in Mulanje District, Malawi. It established the microbiological water-quality safety of 279 community supplies over three phases, each comprising water-quality survey, rehabilitation and treatment verification monitoring. Phase 1 contamination three months after Idai was moderate, but likely underestimated. Increased contamination in Phase 2 at 9 months and even greater in Phase 3, a year after Idai was surprising and concerning, with 40% of supplies then registering E. coli contamination and 20% of supplies deemed 'unsafe'. Without donor support for follow-up interventions, this would have been missed by a typical single-phase flood-relief activity. Contamination rebound at boreholes successfully treated months earlier signifies a systemic problem from persistent sources intensified by groundwater levels likely at a decade high. Problem extent in normal, or drier years is unknown due to absence of routine monitoring of water point E. coli in Malawi. Statistical analysis was not conclusive, but was indicative of damaged borehole infrastructure and increased near-borehole pit-latrine numbers being influential. Spatial analysis including groundwater flow-field definition (an overlooked sector opportunity) revealed 'hit-and-miss' contamination of safe and unsafe boreholes in proximity. Hydrogeological control was shown by increased contamination near flood-affected area and in more recent recharge groundwater otherwise of good quality. Pit latrines are presented as credible e-coli sources in a conceptual model accounting for heterogeneous borehole contamination, wet season influence and rebound behavior. Critical to establish are groundwater level - flow direction, hand-pump plume draw, multiple footprint latrine sources - 'skinny' plumes, borehole short-circuiting and fast natural pathway (e.g. fracture flow) and other source influences. Concerted WASH (Water, Sanitation and Hygiene) sector investment in research and policy driving national water point based E. coli monitoring programs are advocated.
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Affiliation(s)
- Michael O Rivett
- Department of Civil and Environmental Engineering, University of Strathclyde, Glasgow G1 1XJ, UK.
| | | | - Ruth Carter
- Department of Civil and Environmental Engineering, University of Strathclyde, Glasgow G1 1XJ, UK
| | - Rudi C H Thetard
- USAID ONSE Health Activity, Health Programs Group Management Sciences for Health MSH, Lilongwe, Malawi
| | - Morris Tengatenga
- USAID ONSE Health Activity, Health Programs Group Management Sciences for Health MSH, Lilongwe, Malawi
| | - Ann Phoya
- USAID ONSE Health Activity, Health Programs Group Management Sciences for Health MSH, Lilongwe, Malawi
| | - Emma Mbalame
- The Ministry of Forestry and Natural Resources, Lilongwe Headquarters, Private Bag 390, Lilongwe, Malawi
| | | | - Steven Kumwenda
- BASEFlow, Galaxy House, Chichiri, Blantyre, PO Box 30467, Malawi
| | - Prince Mleta
- The Ministry of Forestry and Natural Resources, Lilongwe Headquarters, Private Bag 390, Lilongwe, Malawi
| | - Marc J Addison
- Department of Civil and Environmental Engineering, University of Strathclyde, Glasgow G1 1XJ, UK
| | - Robert M Kalin
- Department of Civil and Environmental Engineering, University of Strathclyde, Glasgow G1 1XJ, UK
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Addison MJ, Rivett MO, Robinson H, Fraser A, Miller AM, Phiri P, Mleta P, Kalin RM. Fluoride occurrence in the lower East African Rift System, Southern Malawi. Sci Total Environ 2020; 712:136260. [PMID: 31945540 DOI: 10.1016/j.scitotenv.2019.136260] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2019] [Revised: 12/18/2019] [Accepted: 12/19/2019] [Indexed: 06/10/2023]
Abstract
Countries located on the East African Rift System (EARS) are vulnerable to fluoride in their groundwater; a vulnerability for the developing country of Malawi at the southern rift periphery that is not well characterised. Groundwater fluoride occurrence in Malawi is documented here to better understand and manage fluoride risks posed. Available literature and Gov't of Malawi archive fluoride data spanning some fifty years have been collated and augmented by our own 2016-18 surveys of groundwater quality in Southern Malawi, targeting deep-sourced springs. In total, fluoride data for 1365 borehole, spring and hot spring samples were assembled. Statistically, 83% of samples were below the 1.5 mg/l WHO limit, concentrations in the 1.5-6 mg/l range between former (pre-1993) and current WHO guidelines at 14%, and those with fluoride above the current Malawi (former WHO) 6 mg/l guideline, at 3%. A lower occurrence than in other zones of the EARS, but indicative of a need for a Malawi Gov't management policy revision and associated management strategies endorsed by several documented incidences of dental fluorosis in proximity to high fluoride groundwater. Increased fluoride is related to increased groundwater temperatures signifying the importance of geothermal groundwater provenance. Temperature data may indeed be used as a proxy indicator of fluoride risk; samples with a temperature >32 °C, contained >6 mg/l fluoride. Structural geological controls appear to allow deep geothermal groundwaters to come to the near surface, as evidenced by increased fluoride in springs and boreholes close to faulted areas. Hydrochemical evaluation shows that fluoride concentrations are influenced by fluorite equilibration and sensitivity to calcium and pH. Recommendations are made to further document the occurrence of fluoride and enhance management of risks due to fluoride in drinking water in Malawi. With fluoride as a key indicator within Sustainable Development Goal number 6, the current Malawi standard and waters with concentration between 1.5 and 6 mg/l will come under increased scrutiny and pose a key challenge to assessment and management efforts.
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Affiliation(s)
- Marc J Addison
- Department of Civil & Environmental Engineering, University of Strathclyde, Glasgow, Scotland, G1 1XJ.
| | - Michael O Rivett
- Department of Civil & Environmental Engineering, University of Strathclyde, Glasgow, Scotland, G1 1XJ
| | - Helen Robinson
- Department of Civil & Environmental Engineering, University of Strathclyde, Glasgow, Scotland, G1 1XJ
| | - Aimee Fraser
- Department of Civil & Environmental Engineering, University of Strathclyde, Glasgow, Scotland, G1 1XJ
| | - Alexandra M Miller
- Department of Civil & Environmental Engineering, University of Strathclyde, Glasgow, Scotland, G1 1XJ
| | - Peaches Phiri
- The Ministry of Agriculture, Irrigation and Water Development, Regional Irrigation and Water Development Office, Lilongwe Headquarters, Private Bag 390, Lilongwe, Malawi
| | - Prince Mleta
- The Ministry of Agriculture, Irrigation and Water Development, Regional Irrigation and Water Development Office, Lilongwe Headquarters, Private Bag 390, Lilongwe, Malawi
| | - Robert M Kalin
- Department of Civil & Environmental Engineering, University of Strathclyde, Glasgow, Scotland, G1 1XJ
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Hassan I, Kalin RM, White CJ, Aladejana JA. Evaluation of Daily Gridded Meteorological Datasets over the Niger Delta Region of Nigeria and Implication to Water Resources Management. ACTA ACUST UNITED AC 2020. [DOI: 10.4236/acs.2020.101002] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Al-Jawad JY, Alsaffar HM, Bertram D, Kalin RM. A comprehensive optimum integrated water resources management approach for multidisciplinary water resources management problems. J Environ Manage 2019; 239:211-224. [PMID: 30901699 DOI: 10.1016/j.jenvman.2019.03.045] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/14/2018] [Revised: 02/26/2019] [Accepted: 03/10/2019] [Indexed: 06/09/2023]
Abstract
A holistic Integrated Water Resources Management (IWRM) model can be difficult to implement and the associated high-dimension optimization problems' complexity often forces the decision makers to downscale such problems. These challenges however have motivated this research to develop a comprehensive Optimum IWRM approach (OP-IWRM) using a many-objective optimization algorithm to solve complex and large-scale problems. The approach employs the social, economic, and environmental objectives; ground and surface water resources; and water infrastructure for river basin management to: (1) improve the relevant revenues, (2) enhance community welfare, and (3) pave the road for the decision makers to set better investment policy. The results demonstrate comprehensive improvement of all considered targets. The decision makers may reconsider implementing complex integrated water resources management of large-scale regions. The OP-IWRM may extend for country-scale approach as a pathway towards a national sustainable development plan. The large-scale Diyala river basin, Iraq, was adopted to evaluate the approach using seventeen objectives and more than 1500 decision variables.
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Affiliation(s)
- Jafar Y Al-Jawad
- Department of Civil and Environmental Engineering, University of Strathclyde Glasgow, 75 Montrose St, Glasgow, G1 1XJ, United Kingdom.
| | - Hassan M Alsaffar
- National Center for Water Resources Management, Ministry of Water Resources, Baghdad, Iraq.
| | - Douglas Bertram
- Department of Civil and Environmental Engineering, University of Strathclyde Glasgow, 75 Montrose St, Glasgow, G1 1XJ, United Kingdom.
| | - Robert M Kalin
- Department of Civil and Environmental Engineering, University of Strathclyde Glasgow, 75 Montrose St, Glasgow, G1 1XJ, United Kingdom.
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Gibert O, Assal A, Devlin H, Elliot T, Kalin RM. Performance of a field-scale biological permeable reactive barrier for in-situ remediation of nitrate-contaminated groundwater. Sci Total Environ 2019; 659:211-220. [PMID: 30599340 DOI: 10.1016/j.scitotenv.2018.12.340] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2018] [Revised: 12/20/2018] [Accepted: 12/22/2018] [Indexed: 06/09/2023]
Abstract
We report the performance of a field-scale permeable reactive barrier (PRB) for the biological treatment of nitrate-contaminated groundwater. The reactive material of the PRB consisted of a mixture of gravel and mulch as a carbon source for denitrifying bacteria. The PRB was equipped with a delivery system that allowed injecting NO3- at controlled rates from the surface directly into the up-gradient layer of the PRB. This way, NO3- concentration entering the PRB was varied (from 1 to 530 mg/L) with the purpose of evaluating the ultimate efficiency of the PRB under different NO3- loadings. The PRB was successful at removing NO3- from groundwater at inlet concentrations up to 280 mg/L (with NO3- removal percentages ≥97%). Monitoring of groundwater at different depths within the PRB provided evidence that NO3- underwent denitrification preferably at the deepest part of the PRB, where more favourable reducing conditions were achieved. Among the shortcomings of the PRB were the fluctuations of groundwater fluxes caused by intense rainfalls during the study period, although they generally did not pose concern for the denitrification capacity of the PRB. Emission fluxes of gases (CO2, CH4 and N2O) from the PRB to the atmosphere were also measured. The results are finally compared with the few others reported existing PRBs for nitrate-contaminated groundwater worldwide.
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Affiliation(s)
- Oriol Gibert
- Chemical Engineering Department, EEBE, Universitat Politècnica de Catalunya (UPC)-BarcelonaTech, c/Eduard Maristany 10-14, Barcelona 08019, Spain; Barcelona Research Center in Multiscale Science and Engineering, EEBE, Universitat Politècnica de Catalunya (UPC)-BarcelonaTech, c/Eduard Maristany 10-14, Barcelona 08019, Spain.
| | - Antoine Assal
- Department of Civil and Environmental Engineering, University of Strathclyde, 75 Montrose St., Glasgow G1 1XJ, United Kingdom
| | - Hayley Devlin
- Department of Civil and Environmental Engineering, University of Strathclyde, 75 Montrose St., Glasgow G1 1XJ, United Kingdom
| | - Trevor Elliot
- School of Natural & Built Environment, Queen's University Belfast, Stranmillis Rd, Belfast BT9 5AG, Antrim, United Kingdom
| | - Robert M Kalin
- Department of Civil and Environmental Engineering, University of Strathclyde, 75 Montrose St., Glasgow G1 1XJ, United Kingdom
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Rivett MO, Budimir L, Mannix N, Miller AVM, Addison MJ, Moyo P, Wanangwa GJ, Phiri OL, Songola CE, Nhlema M, Thomas MAS, Polmanteer RT, Borge A, Kalin RM. Responding to salinity in a rural African alluvial valley aquifer system: To boldly go beyond the world of hand-pumped groundwater supply? Sci Total Environ 2019; 653:1005-1024. [PMID: 30759542 DOI: 10.1016/j.scitotenv.2018.10.337] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/2018] [Revised: 10/24/2018] [Accepted: 10/25/2018] [Indexed: 06/09/2023]
Abstract
Effective response to groundwater salinity in the developing world may critically safeguard drinking-water supplies. Groundwater resources throughout rural Africa are exploited by a vast and increasing number of hand-pumped boreholes for community supply. Our research in TA Ngabu (Shire Valley), Southern Malawi aims to: define groundwater-salinity problem occurrence within the semi-arid alluvial-valley aquifer, rural developing-world setting; critique current capacity to respond; and, to discuss future response options - in particular considering the need to explore alternative options that boldly go beyond the world of hand-pumped groundwater supply. Salinity problem definition was achieved through survey of 419 hand-pumped boreholes that revealed widespread brackish groundwater leading to non-potable (unpalatable) drinking-water supplies. Persistent non-functionality or abandonment of boreholes was typically ascribed to salinity. Whilst salinity is conceptualised to arise from shallow-groundwater evaporation, formation-evaporite dissolution and faulted-area upwelling, sparse data locally renders attribution of salinity sources to individual boreholes difficult. There is a significant need to better resolve the vertical distribution of salinity and local controlling processes. Problem response capacity was hampered by multiple factors, including, sector inertia, low drilling costs compromising water-point integrity, and lack of technical vision for alternatives. Various recommendations are made to improve response capacity continuing to work at the hand-pump supply scale. However, in areas where salinity is significant, exploring the feasibility of other options is advocated in conjunction with technical capacity development. Groundwater options may utilise high borehole yields possible from alluvial aquifers, grossly under-exploited by hand pumps. Groundwater at depth, albeit of unknown quality typically, or pipeline transfers of probable good-quality groundwater from valley-margin units, should be considered. Surface-water pipeline supplies may be viable for (growing) population centres. Canal-fed irrigation schemes (pending for the area), should be multiple-use, protective of groundwater and embrace pipeline drinking-water supply and managed-aquifer-recharge opportunities. Advancing desalination technologies, although presently unaffordable, should be kept under review.
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Affiliation(s)
- Michael O Rivett
- Department of Civil and Environmental Engineering, University of Strathclyde, Glasgow G1 1XJ, UK.
| | - Laura Budimir
- Department of Civil and Environmental Engineering, University of Strathclyde, Glasgow G1 1XJ, UK
| | - Nicholas Mannix
- Department of Civil and Environmental Engineering, University of Strathclyde, Glasgow G1 1XJ, UK
| | - Alexandra V M Miller
- Department of Civil and Environmental Engineering, University of Strathclyde, Glasgow G1 1XJ, UK
| | - Marc J Addison
- Department of Civil and Environmental Engineering, University of Strathclyde, Glasgow G1 1XJ, UK
| | - Phideria Moyo
- The Ministry of Agriculture, Irrigation and Water Development, Regional Irrigation and Water Development Office, South, Private Bag 13, Blantyre, Malawi
| | - Gift J Wanangwa
- The Ministry of Agriculture, Irrigation and Water Development, Regional Irrigation and Water Development Office, South, Private Bag 13, Blantyre, Malawi
| | - Owen L Phiri
- The Ministry of Agriculture, Irrigation and Water Development, Regional Irrigation and Water Development Office, South, Private Bag 13, Blantyre, Malawi
| | - Chrispine E Songola
- District Water Development Office Chikwawa District Council, Private Bag 1, Chikwawa, Malawi
| | | | | | - Reid T Polmanteer
- Department of Civil and Environmental Engineering, University of Strathclyde, Glasgow G1 1XJ, UK
| | - Amando Borge
- Department of Civil and Environmental Engineering, University of Strathclyde, Glasgow G1 1XJ, UK
| | - Robert M Kalin
- Department of Civil and Environmental Engineering, University of Strathclyde, Glasgow G1 1XJ, UK
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Al-Jawad JY, Alsaffar HM, Bertram D, Kalin RM. Optimum socio-environmental flows approach for reservoir operation strategy using many-objectives evolutionary optimization algorithm. Sci Total Environ 2019; 651:1877-1891. [PMID: 30317175 DOI: 10.1016/j.scitotenv.2018.10.063] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2018] [Revised: 09/28/2018] [Accepted: 10/05/2018] [Indexed: 06/08/2023]
Abstract
Water resource system complexity, high-dimension modelling difficulty and computational efficiency challenges often limit decision makers' strategies to combine environmental flow objectives (e.g. water quality, ecosystem) with social flow objectives (e.g. hydropower, water supply and agriculture). Hence, a novel Optimum Social-Environmental Flows (OSEF) with Auto-Adaptive Constraints (AAC) approach introduced as a river basin management decision support tool. The OSEF-AAC approach integrates Socio-Environmental (SE) objectives with convergence booster support to soften any computational challenges. Nine SE objectives and 396 decision variables modelled for Iraq's Diyala river basin. The approach's effectiveness evaluated using two non-environmental models and two inflows' scenarios. The advantage of OSEF-AAC approved, and other decision support alternatives highlighted that could enhance river basin SE sectors' revenues, as river basin economic benefits will improve as well. However, advanced land use and water exploitation policy would need adoption to secure the basin's SE sectors.
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Affiliation(s)
- Jafar Y Al-Jawad
- Department of Civil and Environmental Engineering, University of Strathclyde Glasgow 75 Montrose St, Glasgow G1 1XJ, United Kingdom of Great Britain and Northern Ireland.
| | - Hassan M Alsaffar
- National Center for Water Resources Management, Ministry of Water Resources, Baghdad, Iraq
| | - Douglas Bertram
- Department of Civil and Environmental Engineering, University of Strathclyde Glasgow 75 Montrose St, Glasgow G1 1XJ, United Kingdom of Great Britain and Northern Ireland.
| | - Robert M Kalin
- Department of Civil and Environmental Engineering, University of Strathclyde Glasgow 75 Montrose St, Glasgow G1 1XJ, United Kingdom of Great Britain and Northern Ireland.
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Rivett MO, Halcrow AW, Schmalfuss J, Stark JA, Truslove JP, Kumwenda S, Harawa KA, Nhlema M, Songola C, Wanangwa GJ, Miller AVM, Kalin RM. Local scale water-food nexus: Use of borehole-garden permaculture to realise the full potential of rural water supplies in Malawi. J Environ Manage 2018; 209:354-370. [PMID: 29309961 DOI: 10.1016/j.jenvman.2017.12.029] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2017] [Revised: 10/28/2017] [Accepted: 12/12/2017] [Indexed: 06/07/2023]
Abstract
Local-scale opportunities to address challenges of the water-food nexus in the developing world need to be embraced. Borehole-garden permaculture is advocated as one such opportunity that involves the sustainable use of groundwater spilt at hand-pump operated borehole supplies that is otherwise wasted. Spilt water may also pose health risks when accumulating as a stagnant pond. Rural village community use of this grey-water in permaculture projects to irrigate borehole gardens is proposed to primarily provide economic benefit whereby garden-produce revenue helps fund borehole water-point maintenance. Water-supply sustainability, increased food/nutrition security, health protection from malaria, and business opportunity benefits may also arise. Our goal has been to develop an, experience-based, framework for delivery of sustainable borehole-garden permaculture and associated benefits. This is based upon data collection and permaculture implementation across the rural Chikwawa District of Malawi during 2009-17. We use, stakeholder interviews to identify issues influencing uptake, gathering of stagnant pond occurrence data to estimate amelioration opportunity, quantification of permaculture profitability to validate economic potential, and critical assessment of recent permaculture uptake to identify continuing problems. Permaculture was implemented at 123 sites representing 6% of District water points, rising to 26% local area coverage. Most implementations were at, or near, newly drilled community-supply boreholes; hence, amelioration of prevalent stagnant ponds elsewhere remains a concern. The envisaged benefits of permaculture were manifest and early data affirm projected garden profitability and spin-off benefits of water-point banking and community micro-loan access. However, a diversity of technical, economic, social and governance issues were found to influence uptake and performance. Example issues include greater need for improved bespoke garden design input, on-going project performance assessment, and coordinated involvement of multi-sector governmental-development bodies to underpin the integrated natural-resource management required. The developed framework aims to manage the identified issues and requires the concerted action of all stakeholders. Based on the probable ubiquity of underlying issues, the framework is expected to be generalizable to the wider developing world. However, this particular application of permaculture represents a fraction of its greater potential opportunity for rural communities that should be explored.
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Affiliation(s)
- Michael O Rivett
- Department of Civil and Environmental Engineering, University of Strathclyde, Glasgow, G1 1XJ, UK.
| | - Alistair W Halcrow
- Department of Civil and Environmental Engineering, University of Strathclyde, Glasgow, G1 1XJ, UK
| | - Janine Schmalfuss
- Department of Civil and Environmental Engineering, University of Strathclyde, Glasgow, G1 1XJ, UK
| | - John A Stark
- Department of Civil and Environmental Engineering, University of Strathclyde, Glasgow, G1 1XJ, UK
| | - Jonathan P Truslove
- Department of Civil and Environmental Engineering, University of Strathclyde, Glasgow, G1 1XJ, UK
| | - Steve Kumwenda
- Water for People - Malawi, PO Box 1207, Blantyre, Malawi
| | | | | | - Chrispine Songola
- District Water Development Office, Chikwawa District Council, Private Bag 1, Chikwawa, Malawi
| | - Gift J Wanangwa
- Ministry of Agriculture, Irrigation and Water Development, Regional Irrigation and Water Development Office - South, Private Bag 13, Blantyre, Malawi
| | - Alexandra V M Miller
- Department of Civil and Environmental Engineering, University of Strathclyde, Glasgow, G1 1XJ, UK
| | - Robert M Kalin
- Department of Civil and Environmental Engineering, University of Strathclyde, Glasgow, G1 1XJ, UK
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Back JO, Rivett MO, Hinz LB, Mackay N, Wanangwa GJ, Phiri OL, Songola CE, Thomas MAS, Kumwenda S, Nhlema M, Miller AVM, Kalin RM. Risk assessment to groundwater of pit latrine rural sanitation policy in developing country settings. Sci Total Environ 2018; 613-614:592-610. [PMID: 28926813 DOI: 10.1016/j.scitotenv.2017.09.071] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2017] [Revised: 09/07/2017] [Accepted: 09/07/2017] [Indexed: 05/28/2023]
Abstract
Parallel global rise in pit-latrine sanitation and groundwater-supply provision is of concern due to the frequent spatial proximity of these activities. Study of such an area in Malawi has allowed understanding of risks posed to groundwater from the recent implementation of a typical developing-country pit-latrine sanitation policy to be gained. This has assisted the development of a risk-assessment framework approach pragmatic to regulatory-practitioner management of this issue. The framework involves water-supply and pit-latrine mapping, monitoring of key groundwater contamination indicators and surveys of possible environmental site-condition factors and culminates in an integrated statistical evaluation of these datasets to identify the significant factors controlling risks posed. Our approach usefully establishes groundwater-quality baseline conditions of a potentially emergent issue for the study area. Such baselines are foundational to future trend discernment and contaminant natural attenuation verification critical to policies globally. Attribution of borehole contamination to pit-latrine loading should involve, as illustrated, the use of the range of contamination (chemical, microbiological) tracers available recognising none are ideal and several radial and capture-zone metrics that together may provide a weight of evidence. Elevated, albeit low-concentration, nitrate correlated with some radial metrics and was tentatively suggestive of emerging latrine influences. Longer term monitoring is, however, necessary to verify that the commonly observed latrine-borehole separation distances (29-58m), alongside statutory guidelines, do not constitute significant risk. Borehole contamination was limited and correlation with various environmental-site condition factors also limited. This was potentially ascribed to effectiveness of attenuation to date, monitoring of an emergent problem yet to manifest, or else contamination from other sources. High borehole usage and protective wall absence correlated with observed microbiological contamination incidence, but could relate to increased human/animal activity close to these poorly protected boreholes. Additional to factors assessed, a groundwater-vulnerability factor is recommended that critically relies upon improved proactive securing of underpinning data during borehole/latrine installations. On-going concerns are wide ranging, including poorly constrained pit-latrine input, difficulties in assessing in-situ plume natural attenuation and possible disposal of used motor oils to latrines.
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Affiliation(s)
- Jan O Back
- Department of Civil and Environmental Engineering, University of Strathclyde, Glasgow, G1 1XJ, UK; Department of Environmental, Process and Energy Engineering, MCI-The Entrepreneurial School, Maximilianstraße 2, Innsbruck, Austria
| | - Michael O Rivett
- Department of Civil and Environmental Engineering, University of Strathclyde, Glasgow, G1 1XJ, UK.
| | - Laura B Hinz
- Department of Civil and Environmental Engineering, University of Strathclyde, Glasgow, G1 1XJ, UK; Scottish Water, Castle House, 6 Castle Drive, Dunfermline KY11 8GG, UK
| | - Nyree Mackay
- Department of Civil and Environmental Engineering, University of Strathclyde, Glasgow, G1 1XJ, UK
| | - Gift J Wanangwa
- The Ministry of Agriculture, Irrigation and Water Development, Regional Irrigation and Water Development Office - South, Private Bag 13, Blantyre, Malawi
| | - Owen L Phiri
- The Ministry of Agriculture, Irrigation and Water Development, Regional Irrigation and Water Development Office - South, Private Bag 13, Blantyre, Malawi
| | | | | | - Steve Kumwenda
- Water For People - Malawi, PO Box 1207, Blantyre, Malawi
| | | | - Alexandra V M Miller
- Department of Civil and Environmental Engineering, University of Strathclyde, Glasgow, G1 1XJ, UK
| | - Robert M Kalin
- Department of Civil and Environmental Engineering, University of Strathclyde, Glasgow, G1 1XJ, UK
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Minet EP, Goodhue R, Meier-Augenstein W, Kalin RM, Fenton O, Richards KG, Coxon CE. Combining stable isotopes with contamination indicators: A method for improved investigation of nitrate sources and dynamics in aquifers with mixed nitrogen inputs. Water Res 2017; 124:85-96. [PMID: 28750288 DOI: 10.1016/j.watres.2017.07.041] [Citation(s) in RCA: 71] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2017] [Revised: 07/11/2017] [Accepted: 07/16/2017] [Indexed: 06/07/2023]
Abstract
Excessive nitrate (NO3-) concentration in groundwater raises health and environmental issues that must be addressed by all European Union (EU) member states under the Nitrates Directive and the Water Framework Directive. The identification of NO3- sources is critical to efficiently control or reverse NO3- contamination that affects many aquifers. In that respect, the use of stable isotope ratios 15N/14N and 18O/16O in NO3- (expressed as δ15N-NO3- and δ18O-NO3-, respectively) has long shown its value. However, limitations exist in complex environments where multiple nitrogen (N) sources coexist. This two-year study explores a method for improved NO3- source investigation in a shallow unconfined aquifer with mixed N inputs and a long established NO3- problem. In this tillage-dominated area of free-draining soil and subsoil, suspected NO3- sources were diffuse applications of artificial fertiliser and organic point sources (septic tanks and farmyards). Bearing in mind that artificial diffuse sources were ubiquitous, groundwater samples were first classified according to a combination of two indicators relevant of point source contamination: presence/absence of organic point sources (i.e. septic tank and/or farmyard) near sampling wells and exceedance/non-exceedance of a contamination threshold value for sodium (Na+) in groundwater. This classification identified three contamination groups: agricultural diffuse source but no point source (D+P-), agricultural diffuse and point source (D+P+) and agricultural diffuse but point source occurrence ambiguous (D+P±). Thereafter δ15N-NO3- and δ18O-NO3- data were superimposed on the classification. As δ15N-NO3- was plotted against δ18O-NO3-, comparisons were made between the different contamination groups. Overall, both δ variables were significantly and positively correlated (p < 0.0001, rs = 0.599, slope of 0.5), which was indicative of denitrification. An inspection of the contamination groups revealed that denitrification did not occur in the absence of point source contamination (group D+P-). In fact, strong significant denitrification lines occurred only in the D+P+ and D+P± groups (p < 0.0001, rs > 0.6, 0.53 ≤ slope ≤ 0.76), i.e. where point source contamination was characterised or suspected. These lines originated from the 2-6‰ range for δ15N-NO3-, which suggests that i) NO3- contamination was dominated by an agricultural diffuse N source (most likely the large organic matter pool that has incorporated 15N-depleted nitrogen from artificial fertiliser in agricultural soils and whose nitrification is stimulated by ploughing and fertilisation) rather than point sources and ii) denitrification was possibly favoured by high dissolved organic content (DOC) from point sources. Combining contamination indicators and a large stable isotope dataset collected over a large study area could therefore improve our understanding of the NO3- contamination processes in groundwater for better land use management. We hypothesise that in future research, additional contamination indicators (e.g. pharmaceutical molecules) could also be combined to disentangle NO3- contamination from animal and human wastes.
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Affiliation(s)
- E P Minet
- Geology Department, School of Natural Sciences, Trinity College Dublin, Dublin 2, Ireland; Teagasc Environment Research Centre, Johnstown Castle, Co. Wexford, Ireland.
| | - R Goodhue
- Geology Department, School of Natural Sciences, Trinity College Dublin, Dublin 2, Ireland
| | - W Meier-Augenstein
- Environmental Engineering Research Centre, David Keir Building, Queen's University Belfast, Stranmillis Road, Belfast, BT9 5AG, Northern Ireland, United Kingdom
| | - R M Kalin
- Environmental Engineering Research Centre, David Keir Building, Queen's University Belfast, Stranmillis Road, Belfast, BT9 5AG, Northern Ireland, United Kingdom
| | - O Fenton
- Teagasc Environment Research Centre, Johnstown Castle, Co. Wexford, Ireland
| | - K G Richards
- Teagasc Environment Research Centre, Johnstown Castle, Co. Wexford, Ireland
| | - C E Coxon
- Geology Department, School of Natural Sciences, Trinity College Dublin, Dublin 2, Ireland.
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Gallacher C, Thomas R, Lord R, Kalin RM, Taylor C. Comprehensive database of Manufactured Gas Plant tars. Part C. Heterocyclic and hydroxylated polycyclic aromatic hydrocarbons. Rapid Commun Mass Spectrom 2017; 31:1250-1260. [PMID: 28514513 DOI: 10.1002/rcm.7904] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2016] [Revised: 05/04/2017] [Accepted: 05/06/2017] [Indexed: 06/07/2023]
Abstract
RATIONALE Coal tars are a mixture of organic and inorganic compounds that were by-products from the manufactured gas and coke making industries. The tar compositions varied depending on many factors such as the temperature of production and the type of retort used. For this reason a comprehensive database of the compounds found in different tar types is of value to understand both how their compositions differ and what potential chemical hazards are present. This study focuses on the heterocyclic and hydroxylated compounds present in a database produced from 16 different tars from five different production processes. METHODS Samples of coal tar were extracted using accelerated solvent extraction (ASE) and derivatized post-extraction using N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA) with 1% trimethylchlorosilane (TMCS). The derivatized samples were analysed using two-dimensional gas chromatography combined with time-of-flight mass spectrometry (GCxGC/TOFMS). RESULTS A total of 865 heterocyclic compounds and 359 hydroxylated polycyclic aromatic hydrocarbons (PAHs) were detected in 16 tar samples produced by five different processes. The contents of both heterocyclic and hydroxylated PAHs varied greatly with the production process used, with the heterocyclic compounds giving information about the feedstock used. Of the 359 hydroxylated PAHs detected the majority would not have been be detected without the use of derivatization. CONCLUSIONS Coal tars produced using different production processes and feedstocks yielded tars with significantly different heterocyclic and hydroxylated contents. The concentrations of the individual heterocyclic compounds varied greatly even within the different production processes and provided information about the feedstock used to produce the tars. The hydroxylated PAH content of the samples provided important analytical information that would otherwise not have been obtained without the use of derivatization and GCxGC/TOFMS.
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Affiliation(s)
- Christopher Gallacher
- Department of Civil and Environmental Engineering, University of Strathclyde, 75 Montrose St., Glasgow, G1 1XJ, UK
| | - Russell Thomas
- WSP/Parsons Brinckerhoff, Kings Orchard, 1 Queen St, Bristol, BS2 0HQ, UK
| | - Richard Lord
- Department of Civil and Environmental Engineering, University of Strathclyde, 75 Montrose St., Glasgow, G1 1XJ, UK
| | - Robert M Kalin
- Department of Civil and Environmental Engineering, University of Strathclyde, 75 Montrose St., Glasgow, G1 1XJ, UK
| | - Chris Taylor
- National Grid Property, Warwick Technology Park, Warwick, CV34 6DA, UK
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Gallacher C, Thomas R, Lord R, Kalin RM, Taylor C. Comprehensive database of Manufactured Gas Plant tars. Part B. Aliphatic and aromatic compounds. Rapid Commun Mass Spectrom 2017; 31:1239-1249. [PMID: 28494122 DOI: 10.1002/rcm.7900] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2016] [Revised: 03/30/2017] [Accepted: 05/06/2017] [Indexed: 05/20/2023]
Abstract
RATIONALE Coal tars are a mixture of organic and inorganic compounds that were produced as a by-product from the manufactured gas and coke making industries. The composition of the tar produced varies depending on many factors; these include the temperature of production and the type of retort used. As different production processes produce different tars, a comprehensive database of the compounds present within coal tars from different production processes is a valuable resource. Such a database would help to understand how their chemical properties differ and what hazards the compounds present within these tars might pose. This study focuses on the aliphatic and aromatic compounds present in a database of 16 different tars from five different production processes. METHODS Samples of coal tar were extracted using accelerated solvent extraction (ASE) and derivatised post-extraction using N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA) with 1% trimethylchlorosilane (TMCS). The derivatised samples were analysed using two-dimensional gas chromatography combined with time-of-flight mass spectrometry (GCxGC/TOFMS). RESULTS A total of 198 individual aliphatic and 951 individual aromatic compounds were detected within 16 tar samples produced by five different production processes. The polycyclic aromatic hydrocarbon (PAH) content of coal tars varies greatly depending on the production process used to obtain the tars and this is clearly demonstrated within the results. The aliphatic composition of the tars provided an important piece of analytical information that would have otherwise been missed with the detection of petrogenic compounds such as alkyl cyclohexanes. CONCLUSIONS The aromatic compositions of the tar samples varied greatly between the different production processes investigated and useful analytical information was obtained about the individual production process groups. Alkyl cyclohexanes were detected in all samples from sites known to operate Carbureted Water Gas plants and not detected in those that did not. This suggests that petrogenic material may be expected at many UK gaswork sites.
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Affiliation(s)
- Christopher Gallacher
- Department of Civil and Environmental Engineering, University of Strathclyde, 75 Montrose St., Glasgow, G1 1XJ, UK
| | - Russell Thomas
- WSP/Parsons Brinckerhoff, Kings Orchard, 1 Queen St, Bristol, BS2 0HQ, UK
| | - Richard Lord
- Department of Civil and Environmental Engineering, University of Strathclyde, 75 Montrose St., Glasgow, G1 1XJ, UK
| | - Robert M Kalin
- Department of Civil and Environmental Engineering, University of Strathclyde, 75 Montrose St., Glasgow, G1 1XJ, UK
| | - Chris Taylor
- National Grid Property, Warwick Technology Park, Warwick, CV34 6DA, UK
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Gallacher C, Thomas R, Lord R, Kalin RM, Taylor C. Comprehensive database of Manufactured Gas Plant tars. Part A. Database. Rapid Commun Mass Spectrom 2017; 31:1231-1238. [PMID: 28488792 DOI: 10.1002/rcm.7901] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2016] [Revised: 03/30/2017] [Accepted: 05/06/2017] [Indexed: 06/07/2023]
Abstract
RATIONALE Coal tars are a mixture of organic and inorganic compounds that were by-products from the manufactured gas and coke making industries. Different manufacturing processes have resulted in the production of distinctly different tar compositions. This study presents a comprehensive database of compounds produced using two-dimensional gas chromatography combined with time-of-flight mass spectrometry (GCxGC/TOFMS), analysing 16 tar samples produced by five distinct production processes. METHODS Samples of coal tar were extracted using accelerated solvent extraction (ASE) and derivatised post-extraction using N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA) with 1% trimethylchlorosilane (TMCS). The derivatised samples were analysed using two-dimensional gas chromatography combined with time-of-flight mass spectrometry (GCxGC/TOFMS). RESULTS A total of 16 tar samples originating from five different production processes: Low Temperature Horizontal Retorts, Horizontal Retorts, Vertical Retorts, Carbureted Water Gas and Coke Ovens, were analysed. A total of 2369 unique compounds were detected with 948 aromatic compounds, 196 aliphatic compounds, 380 sulfur-containing compounds, 209 oxygen-containing compounds, 262 nitrogen-containing compounds and 15 mixed heterocycles. Derivatisation allowed the detection of 359 unique compounds, the majority in the form of hydroxylated polycyclic aromatic hydrocarbons, many of which would not have been detected without derivatisation. Of the 2369 unique compounds detected, 173 were found to be present within all samples. CONCLUSIONS A unique comprehensive database of compounds detected within 16 tar samples from five different production processes was produced. The 173 compounds identified within every sample may be of particular importance from a regulatory standpoint. This initial study indicates that different production processes produce tars with different chemical signatures and it can be further expanded upon by in-depth analysis of the different compound types. The number of compounds presented within this database clearly demonstrates the analytical power of GCxGC/TOFMS.
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Affiliation(s)
- Christopher Gallacher
- Department of Civil and Environmental Engineering, University of Strathclyde, 75 Montrose St., Glasgow, G1 1XJ, UK
| | - Russell Thomas
- WSP/Parsons Brinckerhoff, Kings Orchard, 1 Queen St, Bristol, BS2 0HQ, UK
| | - Richard Lord
- Department of Civil and Environmental Engineering, University of Strathclyde, 75 Montrose St., Glasgow, G1 1XJ, UK
| | - Robert M Kalin
- Department of Civil and Environmental Engineering, University of Strathclyde, 75 Montrose St., Glasgow, G1 1XJ, UK
| | - Chris Taylor
- National Grid Property, Warwick Technology Park, Warwick, CV34 6DA, UK
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Affiliation(s)
- Robert M. Kalin
- The Queen’s University of Belfast Dept. of Civil Engineering. Belfast, Northern Ireland BT7 INN 44-232-24-5133 Ext.4018
| | | | - Gregory Hall
- Westinghouse Savannah River Company Aiken, SC, USA (803) 725-5451
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16
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Gallacher C, Thomas R, Taylor C, Lord R, Kalin RM. Comprehensive composition of Creosote using comprehensive two-dimensional gas chromatography time-of-flight mass spectrometry (GCxGC-TOFMS). Chemosphere 2017; 178:34-41. [PMID: 28315805 DOI: 10.1016/j.chemosphere.2017.03.050] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2016] [Revised: 03/10/2017] [Accepted: 03/11/2017] [Indexed: 06/06/2023]
Abstract
Creosote is a distillation product of coal tar and is widely used as wood preservative for railway sleepers, utility poles and for other applications. Creosote can have potentially negative effects on the environment and many of the components are toxic. This study presents the analysis of a Creosote sample from a former wood impregnation plant located in the UK. The sample was analysed using two dimensional gas chromatography time-of-flight mass spectrometry (GCxGC-TOFMS) and a database of compounds that could be detected was produced. The GCxGG-TOFMS was capable of detecting 1505 individual compounds, which is far more than previous estimates for the number of compounds present within Creosote. Post extraction derivatization using BTSFA with 1% TMCS was employed to increase the potential number of compounds detected with 255 derivatized compounds detected, 231 of which would not have been detected without prior derivatization. Selected derivatized compounds were quantified with limits of detection ranging from 0.6 mg/kg to 1.6 mg/kg from a concentrated dense non-aqueous phase liquid (DNAPL). This work presents the first published full analysis of a Creosote using GCxGC-TOFMS combined with derivatization.
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Affiliation(s)
- Christopher Gallacher
- Department of Civil and Env. Eng., University of Strathclyde, 75 Montrose St., Glasgow, UK.
| | - Russell Thomas
- WSP/Parsons Brinckerhoff, Kings Orchard, 1 Queen St, Bristol, UK
| | - Christopher Taylor
- National Grid Property Holdings Ltd, National Grid House, Warwick Technology Park, Gallows Hill, Warwick, UK
| | - Richard Lord
- Department of Civil and Env. Eng., University of Strathclyde, 75 Montrose St., Glasgow, UK
| | - Robert M Kalin
- Department of Civil and Env. Eng., University of Strathclyde, 75 Montrose St., Glasgow, UK
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Gauchotte-Lindsay C, McGregor LA, Assal A, Thomas R, Kalin RM. Highlighting the Effects of Co-eluting Interferences on Compound-Specific Stable Isotope Analysis of Polycyclic Aromatic Hydrocarbons by Using Comprehensive Two-Dimensional Gas Chromatography. Chempluschem 2014. [DOI: 10.1002/cplu.201400026] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Ndilila W, Callan AC, McGregor LA, Kalin RM, Hinwood AL. Environmental and toenail metals concentrations in copper mining and non mining communities in Zambia. Int J Hyg Environ Health 2014; 217:62-9. [DOI: 10.1016/j.ijheh.2013.03.011] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2012] [Revised: 03/19/2013] [Accepted: 03/21/2013] [Indexed: 11/30/2022]
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Wang Y, Chen Y, Zhou Q, Huang S, Ning K, Xu J, Kalin RM, Rolfe S, Huang WE. A culture-independent approach to unravel uncultured bacteria and functional genes in a complex microbial community. PLoS One 2012; 7:e47530. [PMID: 23082176 PMCID: PMC3474725 DOI: 10.1371/journal.pone.0047530] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2012] [Accepted: 09/12/2012] [Indexed: 01/23/2023] Open
Abstract
Most microorganisms in nature are uncultured with unknown functionality. Sequence-based metagenomics alone answers ‘who/what are there?’ but not ‘what are they doing and who is doing it and how?’. Function-based metagenomics reveals gene function but is usually limited by the specificity and sensitivity of screening strategies, especially the identification of clones whose functional gene expression has no distinguishable activity or phenotypes. A ‘biosensor-based genetic transducer’ (BGT) technique, which employs a whole-cell biosensor to quantitatively detect expression of inserted genes encoding designated functions, is able to screen for functionality of unknown genes from uncultured microorganisms. In this study, BGT was integrated with Stable isotope probing (SIP)-enabled Metagenomics to form a culture-independent SMB toolbox. The utility of this approach was demonstrated in the discovery of a novel functional gene cluster in naphthalene contaminated groundwater. Specifically, metagenomic sequencing of the 13C-DNA fraction obtained by SIP indicated that an uncultured Acidovorax sp. was the dominant key naphthalene degrader in-situ, although three culturable Pseudomonas sp. degraders were also present in the same groundwater. BGT verified the functionality of a new nag2 operon which co-existed with two other nag and two nah operons for naphthalene biodegradation in the same microbial community. Pyrosequencing analysis showed that the nag2 operon was the key functional operon in naphthalene degradation in-situ, and shared homology with both nag operons in Ralstonia sp. U2 and Polaromonas naphthalenivorans CJ2. The SMB toolbox will be useful in providing deep insights into uncultured microorganisms and unravelling their ecological roles in natural environments.
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Affiliation(s)
- Yun Wang
- Kroto Research Institute, University of Sheffield, Sheffield, England, United Kingdom
| | - Yin Chen
- School of Life Sciences, University of Warwick, Coventry, England, United Kingdom
| | - Qian Zhou
- BioEnergy Genome Centre, Chinese Academy of Sciences Key Laboratory of Biofuels and Shandong Key Laboratory of Energy Genetics, Qingdao Institute of BioEnergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, China
| | - Shi Huang
- BioEnergy Genome Centre, Chinese Academy of Sciences Key Laboratory of Biofuels and Shandong Key Laboratory of Energy Genetics, Qingdao Institute of BioEnergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, China
| | - Kang Ning
- BioEnergy Genome Centre, Chinese Academy of Sciences Key Laboratory of Biofuels and Shandong Key Laboratory of Energy Genetics, Qingdao Institute of BioEnergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, China
| | - Jian Xu
- BioEnergy Genome Centre, Chinese Academy of Sciences Key Laboratory of Biofuels and Shandong Key Laboratory of Energy Genetics, Qingdao Institute of BioEnergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, China
| | - Robert M. Kalin
- David Livingstone Centre for Sustainability, Strathclyde University, Glasgow, Scotland, United Kingdom
| | - Stephen Rolfe
- Department of Animal and Plant Sciences, Alfred Denny Building, University of Sheffield, Sheffield, England, United Kingdom
| | - Wei E. Huang
- Kroto Research Institute, University of Sheffield, Sheffield, England, United Kingdom
- * E-mail:
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Minet E, Coxon CE, Goodhue R, Richards KG, Kalin RM, Meier-Augenstein W. Evaluating the utility of 15N and 18O isotope abundance analyses to identify nitrate sources: A soil zone study. Water Res 2012; 46:3723-3736. [PMID: 22578428 DOI: 10.1016/j.watres.2012.03.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/22/2011] [Revised: 02/08/2012] [Accepted: 03/04/2012] [Indexed: 05/31/2023]
Abstract
(15)N and (18)O isotope abundance analyses in nitrate (NO(3)(-)) (expressed as δ(15)N-NO(3)(-) and δ(18)O-NO(3)(-) values respectively) have often been used in research to help identify NO(3)(-) sources in rural groundwater. However, questions have been raised over the limitations as overlaps in δ values may occur between N source types early in the leaching process. The aim of this study was to evaluate the utility of using stable isotopes for nitrate source tracking through the determination of δ(15)N-NO(3)(-) and δ(18)O-NO(3)(-) in the unsaturated zone from varying N source types (artificial fertiliser, dairy wastewater and cow slurry) and rates with contrasting isotopic compositions. Despite NO(3)(-) concentrations being often elevated, soil-water nitrate poorly mirrored the (15)N content of applied N and therefore, δ(15)N-NO(3)(-) values were of limited assistance in clearly associating nitrate leaching with N inputs. Results suggest that the mineralisation and the nitrification of soil organic N, stimulated by previous and current intensive management, masked the cause of leaching from the isotopic prospective. δ(18)O-NO(3)(-) was of little use, as most values were close to or within the range expected for nitrification regardless of the treatment, which was attributed to the remineralisation of nitrate assimilated by bacteria (mineralisation-immobilisation turnover or MIT) or plants. Only in limited circumstances (low fertiliser application rate in tillage) could direct leaching of synthetic nitrate fertiliser be identified (δ(15)N-NO(3)(-)<0‰ and δ(18)O-NO(3)(-)>15‰). Nevertheless, some useful differences emerged between treatments. δ(15)N-NO(3)(-) values were lower where artificial fertiliser was applied compared with the unfertilised controls and organic waste treatments. Importantly, δ(15)N-NO(3)(-) and δ(18)O-NO(3)(-) variables were negatively correlated in the artificial fertiliser treatment (0.001≤p≤0.05, attributed to the varying proportion of fertiliser-derived and synthetic nitrate being leached) while positively correlated in the dairy wastewater plots (p≤0.01, attributed to limited denitrification). These results suggest that it may be possible to distinguish some nitrate sources if analysing correlations between δ variables from the unsaturated zone. In grassland, the above correlations were related to N input rates, which partly controlled nitrate concentrations in the artificial fertiliser plots (high inputs translated into higher NO(3)(-) concentrations with an increasing proportion of fertiliser-derived and synthetic nitrate) and denitrification in the dairy wastewater plots (high inputs corresponded to more denitrification). As a consequence, nitrate source identification in grassland was more efficient at higher input rates due to differences in δ values widening between treatments.
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Affiliation(s)
- E Minet
- Geology Department, School of Natural Sciences, Trinity College Dublin, Dublin 2, Ireland.
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21
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McGregor LA, Gauchotte-Lindsay C, Daéid NN, Thomas R, Kalin RM. Multivariate statistical methods for the environmental forensic classification of coal tars from former manufactured gas plants. Environ Sci Technol 2012; 46:3744-3752. [PMID: 22335394 DOI: 10.1021/es203708w] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Compositional disparity within a set of 23 coal tar samples (obtained from 15 different former manufactured gas plants) was compared and related to differences between historical on-site manufacturing processes. Samples were prepared using accelerated solvent extraction prior to analysis by two-dimensional gas chromatography coupled to time-of-flight mass spectrometry. A suite of statistical techniques, including univariate analysis, hierarchical cluster analysis, two-dimensional cluster analysis, and principal component analysis (PCA), were investigated to determine the optimal method for source identification of coal tars. The results revealed that multivariate statistical analysis (namely, PCA of normalized, preprocessed data) has the greatest potential for environmental forensic source identification of coal tars, including the ability to predict the processes used to create unknown samples.
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Affiliation(s)
- Laura A McGregor
- David Livingstone Centre for Sustainability, Department of Civil and Environmental Engineering, University of Strathclyde, Glasgow, United Kingdom.
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Abstract
Carbon stable isotope ((13)C) fractionation in chlorofluorocarbon (CFC) compounds arising from abiotic (chemical) degradation using zero-valent iron (ZVI) and biotic (landfill gas attenuation) processes is investigated. Batch tests (at 25 °C) for CFC-113 and CFC-11 using ZVI show quantitative degradation of CFC-113 to HCFC-123a and CFC-1113 following pseudo-first-order kinetics corresponding to a half-life (τ(1/2)) of 20.5 h, and a ZVI surface-area normalized rate constant (k(SA)) of -(9.8 ± 0.5) × 10(-5) L m(-2) h(-1). CFC-11 degraded to trace HCFC-21 and HCFC-31 following pseudo-first-order kinetics corresponding to τ(1/2) = 17.3 h and k(SA) = -(1.2 ± 0.5) × 10(-4) L m(-2) h(-1). Significant kinetic isotope effects of ε(‰) = -5.0 ± 0.3 (CFC-113) and -17.8 ± 4.8 (CFC-11) were observed. Compound-specific carbon isotope analyses also have been used here to characterize source signatures of CFC gases (HCFC-22, CFC-12, HFC-134a, HCFC-142b, CFC-114, CFC-11, CFC-113) for urban (UAA), rural/remote (RAA), and landfill (LAA) ambient air samples, as well as in situ surface flux chamber (FLUX; NO FLUX) and landfill gas (LFG) samples at the Dargan Road site, Northern Ireland. The latter values reflect biotic degradation and isotopic fractionation in LFG production, and local atmospheric impact of landfill emissions through the cover. Isotopic fractionations of Δ(13)C ∼ -13‰ (HCFC-22), Δ(13)C ∼ -35‰ (CFC-12) and Δ(13)C ∼ -15‰ (CFC-11) were observed for LFG in comparison to characteristic solvent source signatures, with the magnitude of the isotopic effect for CFC-11 apparently similar to the kinetic isotope effect for (abiotic) ZVI degradation.
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Affiliation(s)
- Marie E Archbold
- Environmental Engineering Research Centre (EERC), Queen's University Belfast, School of Planning, Architecture & Civil Engineering, David Keir Building, Stranmillis Road, Belfast, Northern Ireland, BT9 5AG, United Kingdom
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Minet E, Goodhue R, Coxon CE, Kalin RM, Meier-Augenstein W. Simplifying and improving the extraction of nitrate from freshwater for stable isotope analyses. ACTA ACUST UNITED AC 2011; 13:2062-6. [DOI: 10.1039/c1em10289c] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Phillips DH, Van Nooten T, Bastiaens L, Russell MI, Dickson K, Plant S, Ahad JME, Newton T, Elliot T, Kalin RM. Ten year performance evaluation of a field-scale zero-valent iron permeable reactive barrier installed to remediate trichloroethene contaminated groundwater. Environ Sci Technol 2010; 44:3861-3869. [PMID: 20420442 DOI: 10.1021/es902737t] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
The Monkstown zero-valent iron permeable reactive barrier (ZVI PRB), Europe's oldest commercially-installed ZVI PRB, had been treating trichloroethene (TCE) contaminated groundwater for about 10 years on the Nortel Network site in Northern Ireland when cores from the reactive zone were collected in December, 2006. Groundwater data from 2001-2006 indicated that TCE is still being remediated to below detection limits as the contaminated groundwater flows through the PRB. Ca and Fe carbonates, crystalline and amorphous Fe sulfides, and Fe (hydr)oxides have precipitated in the granular ZVI material in the PRB. The greatest variety of minerals is associated with a approximately 1-2 cm thick, slightly cemented crust on top (up-gradient influent entrance) of the ZVI section of the PRB and also with the discontinuous cemented ZVI material ( approximately 23 cm thick) directly below it. The greatest presence of microbial communities also occurred in the up-gradient influent portion of the PRB compared to its down-gradient effluent section, with the latter possibly due to less favorable conditions (i.e., high pH, low oxygen) for microbial growth. The ZVI filings in the down-gradient effluent section of the PRB have a projected life span of >10 years compared with ZVI filings from the continuous to discontinuous cemented up-gradient ZVI section (upper approximately 25 cm) of the PRB, which may have a life span of only approximately 2-5 more years. Supporting Information from applied, multi-tracer testing indicated that restricted groundwater flow is occurring in the upper approximately 25 cm of the ZVI section and preferential pathways have also formed in this PRB over its 10 years of operation.
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Affiliation(s)
- D H Phillips
- Environmental Engineering Research Centre, School of Planning, Architecture & Civil Engineering, Queen's University Belfast, Belfast BT9 5AG, Northern Ireland, U.K.
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Gauchotte C, O'Sullivan G, Davis S, Kalin RM. Development of an advanced on-line position-specific stable carbon isotope system and application to methyl tert-butyl ether. Rapid Commun Mass Spectrom 2009; 23:3183-3193. [PMID: 19725079 DOI: 10.1002/rcm.4222] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
We present an advanced system for on-line position-specific carbon isotope analysis. The main limitation of on-line intramolecular isotope ratio measurements has been that optimal pyrolytic fragments are obtained mostly at temperatures where the analyte has not completely reacted. As a result of undetermined isotopic fractionation, the isotopic signatures of the pyrolysis products are not strictly equal to these of the equivalent moieties in the parent molecule. We designed a pyrolytic unit in which both temperature and reaction time are variable parameters, enabling determination of the enrichment factor of the pyrolysis at optimal temperature by construction of a Rayleigh plot. In the case of methyl tert-butyl ether (MTBE) presented here, a 'pre-pyrolysis' fractionation of MTBE leading to a depletion of 0.9 per thousand was discovered and the enrichment factor of the optimal pyrolysis reaction was determined at -1.7 per thousand. Absolute delta(13)C values of two functional groups of MTBE - the methoxy group and the 2-methylpropane group - could be determined with 95% confidence intervals of 0.4 per thousand and 0.5 per thousand, respectively.
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Affiliation(s)
- Caroline Gauchotte
- Department of Civil Engineering, University of Strathclyde, John Anderson Building, Glasgow G4 0NG, UK.
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Gibert O, Pomierny S, Rowe I, Kalin RM. Selection of organic substrates as potential reactive materials for use in a denitrification permeable reactive barrier (PRB). Bioresour Technol 2008; 99:7587-7596. [PMID: 18353637 DOI: 10.1016/j.biortech.2008.02.012] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2007] [Revised: 02/01/2008] [Accepted: 02/10/2008] [Indexed: 05/26/2023]
Abstract
The aim of the present study was to select a suitable natural organic substrate as a potential carbon source for use in a denitrification permeable reactive barrier (PRB). A number of seven organic substrates were first tested in batch tests. The materials attained varying degrees of success at promoting denitrification. Some of the organic substrates performed very well, achieving complete nitrate removal (>98%), while others were considered unsuitable for a variety of reasons, including: insufficient nitrate or nitrogen removal, excessive release of leachable nitrogen from the substrate or excessive reduction of nitrate to ammonium rather than removing it as gaseous N2. The top performing substrate in terms of denitrification extent (>98%) and rate (0.067 mgNO3(-)-N dm(-3)d(-1)g(sub)(-1)) was then selected for two bench-scale column experiments in an attempt to simulate the PRB. The inlet concentration was 50 mg dm(-3) NO3(-)-N and the columns operated at two different flow rates: 0.3 cm3 min(-1) (Column 1) and 1.1cm3 min(-1) (Column 2). The two columns showed different general patterns, making it clear that the flow rate was a key factor at the nitrate removal. Nitrate was completely removed (>96%) by the passage through Column 1, while only partially removed in Column 2 (66%). The results indicated that the selected organic substrate (Softwood) was applicable for further use as a filling material for a PRB.
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Affiliation(s)
- Oriol Gibert
- EERC, School of Planning Architecture and Civil Engineering, Queen's University Belfast, Stranmillis Road, Belfast, Northern Ireland BT9 5AG, United Kingdom.
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27
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Fraser I, Meier-Augenstein W, Kalin RM. Stable Isotope Analysis of Human Hair and Nail Samples: The Effects of Storage on Samples. J Forensic Sci 2008; 53:95-9. [DOI: 10.1111/j.1556-4029.2007.00607.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Gibert O, Ferguson AS, Kalin RM, Doherty R, Dickson KW, McGeough KL, Robinson J, Thomas R. Performance of a sequential reactive barrier for bioremediation of coal tar contaminated groundwater. Environ Sci Technol 2007; 41:6795-801. [PMID: 17969697 DOI: 10.1021/es071527f] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Following a thorough site investigation, a biological Sequential Reactive Barrier (SEREBAR), designed to remove Polycyclic Aromatic Hydrocarbons (PAHs) and BTEX compounds, was installed at a Former Manufactured Gas Plant (FMGP) site. The novel design of the barrier comprises, in series, an interceptor and six reactive chambers. The first four chambers (2 nonaerated-2 aerated) were filled with sand to encourage microbial colonization. Sorbant Granular Activated Carbon (GAC) was present in the final two chambers in order to remove any recalcitrant compounds. The SEREBAR has been in continuous operation for 2 years at different operational flow rates (ranging from 320 L/d to 4000 L/d, with corresponding residence times in each chamber of 19 days and 1.5 days, respectively). Under low flow rate conditions (320-520 L/d) the majority of contaminant removal (>93%) occurred biotically within the interceptor and the aerated chambers. Under high flow rates (1000-4000 L/d) and following the installation of a new interceptor to prevent passive aeration, the majority of contaminant removal (>80%) again occurred biotically within the aerated chambers. The sorption zone (GAC) proved to be an effective polishing step, removing any remaining contaminants to acceptable concentrations before discharge down-gradient of the SEREBAR (overall removals >95%).
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Affiliation(s)
- Oriol Gibert
- EERC, School of Planning Architecture and Civil Engineering, Queen's University Belfast, David Keir Building, Stranmillis Road, Belfast BT9 5AG, United Kingdom.
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Abstract
The use of zero valent iron (Fe0) for the remediation of water contaminated with carbon disulfide (CS2), a common groundwater contaminant, has been evaluated in this study. Mineralogical analysis of Fe0 filings and polished Fe0 cross-sections indicates that iron sulfide is formed due to the removal of carbon disulfide from solution by Fe0. The kinetics of CS2 removal by Fe0 was examined through both batch and column testing, and it is demonstrated that CS2 is removed rapidly from solution. A linear relationship was observed, through batch testing, between the pseudo-first-order rate constant (k(obs)) and the surface area concentration of Fe0 (rho(a)). Data obtained from kinetic batch tests performed at four temperature levels conformed to the Arrhenius equation, and the calculated apparent activation energy (E(a)) was 37 +/- 2.3 kJ mol(-1), indicating that the kinetics of CS2 removal by Fe0 is controlled by a chemical surface reaction. The temperature correction factors for CS2 from a reference of 25 degrees C were x 1.4 for 18 degrees C, x 1.7 for 15 degrees C, x 2.0 for 12 degrees C, and x 2.3 for 9 degrees C. Surface area normalization of k(obs) obtained through batch and column testing gives specific reaction rate constants (k(SA)) within 1 order of magnitude, indicating that k(SA) values are useful as a general descriptor of CS2-Fe0 reaction kinetics and that these values provide a clear starting point for design calculations prior to commencing site-specific treatability studies for permeable reactive barrier design.
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Affiliation(s)
- Karen L McGeough
- Environmental Engineering Research Centre, School of Planning, Architecture, and Civil Engineering, Queen's University Belfast, Belfast BT9 5AG, United Kingdom.
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Ferguson AS, Huang WE, Lawson KA, Doherty R, Gibert O, Dickson KW, Whiteley AS, Kulakov LA, Thompson IP, Kalin RM, Larkin MJ. Microbial analysis of soil and groundwater from a gasworks site and comparison with a sequenced biological reactive barrier remediation process. J Appl Microbiol 2007; 102:1227-38. [PMID: 17448158 DOI: 10.1111/j.1365-2672.2007.03398.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
AIMS To investigate the distribution of a polymicrobial community of biodegradative bacteria in (i) soil and groundwater at a former manufactured gas plant (FMGP) site and (ii) in a novel SEquential REactive BARrier (SEREBAR) bioremediation process designed to bioremediate the contaminated groundwater. METHODS AND RESULTS Culture-dependent and culture-independent analyses using denaturing gradient gel electrophoresis (DGGE) and polymerase chain reaction (PCR) for the detection of 16S ribosomal RNA gene and naphthalene dioxygenase (NDO) genes of free-living (planktonic groundwater) and attached (soil biofilm) samples from across the site and from the SEREBAR process was applied. Naphthalene arising from groundwater was effectively degraded early in the process and the microbiological analysis indicated a dominant role for Pseudomonas and Comamonas in its degradation. The microbial communities appeared highly complex and diverse across both the sites and in the SEREBAR process. An increased population of naphthalene degraders was associated with naphthalene removal. CONCLUSION The distribution of micro-organisms in general and naphthalene degraders across the site was highly heterogeneous. Comparisons made between areas contaminated with polycyclic aromatic hydrocarbons (PAH) and those not contaminated, revealed differences in the microbial community profile. The likelihood of noncultured bacteria being dominant in mediating naphthalene removal was evident. SIGNIFICANCE AND IMPACT OF THE STUDY This work further emphasizes the importance of both traditional and molecular-based tools in determining the microbial ecology of contaminated sites and highlights the role of noncultured bacteria in the process.
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Affiliation(s)
- A S Ferguson
- QUESTOR Centre and EERC School of Planning Architechture and Civil Engineering, David Keir Building, The Queen's University of Belfast, Belfast, UK
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31
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Keppler F, Harper DB, Kalin RM, Meier-Augenstein W, Farmer N, Davis S, Schmidt HL, Brown DM, Hamilton JTG. Stable hydrogen isotope ratios of lignin methoxyl groups as a paleoclimate proxy and constraint of the geographical origin of wood. New Phytol 2007; 176:600-609. [PMID: 17725557 DOI: 10.1111/j.1469-8137.2007.02213.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Stable isotope ratios of organic compounds are valuable tools for determining the geographical origin, identity, authenticity or history of samples from a vast range of sources such as sediments, plants and animals, including humans. Hydrogen isotope ratios (delta(2)H values) of methoxyl groups in lignin from wood of trees grown in different geographical areas were measured using compound-specific pyrolysis isotope ratio mass spectrometry analysis. Lignin methoxyl groups were depleted in (2)H relative to both meteoric water and whole wood. A high correlation (r(2) = 0.91) was observed between the delta(2)H values of the methoxyl groups and meteoric water, with a relatively uniform fractionation of -216 +/- 19 per thousand recorded with respect to meteoric water over a range of delta(2)H values from -110 in northern Norway to +20 per thousand in Yemen. Thus, woods from northern latitudes can be clearly distinguished from those from tropical regions. By contrast, the delta(2)H values of bulk wood were only relatively poorly correlated (r(2) = 0.47) with those of meteoric water. Measurement of the delta(2)H values of lignin methoxyl groups is potentially a powerful tool that could be of use not only in the constraint of the geographical origin of lignified material but also in paleoclimate, food authenticity and forensic investigations.
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Affiliation(s)
- Frank Keppler
- Max-Planck-Institute for Chemistry, Joh.-Joachim-Becher-Weg 2, 55128 Mainz, Germany
| | - David B Harper
- School of Agriculture and Food Science, Newforge Lane, Belfast BT9 5PX, UK
| | - Robert M Kalin
- School of Planning Architecture and Civil Engineering, Queen's University Belfast, Belfast BT9 5AG, UK
| | - Wolfram Meier-Augenstein
- School of Planning Architecture and Civil Engineering, Queen's University Belfast, Belfast BT9 5AG, UK
| | - Nicola Farmer
- School of Planning Architecture and Civil Engineering, Queen's University Belfast, Belfast BT9 5AG, UK
| | | | - Hanns-Ludwig Schmidt
- Technische Universität München, Lehrstuhl für Biologische Chemie, An der Saatzucht 5, D-85350 Freising-Weihenstephan, Germany
| | - David M Brown
- Department of Archaeology & Palaeoecology, Queen's University Belfast, Belfast BT9 5AG, UK
| | - John T G Hamilton
- School of Agriculture and Food Science, Newforge Lane, Belfast BT9 5PX, UK
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Fraser I, Meier-Augenstein W, Kalin RM. The role of stable isotopes in human identification: a longitudinal study into the variability of isotopic signals in human hair and nails. Rapid Commun Mass Spectrom 2006; 20:1109-16. [PMID: 16521167 DOI: 10.1002/rcm.2424] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
Recent natural catastrophes with large-scale loss of life have demonstrated the need for a new technique to provide information for disaster victim identification when DNA methods fail to yield the identification of an individual, or in other situations where authorities need to determine the recent geographical life history of people. The latter may be in relation to the identification of individuals detained on suspicion of terrorism or in relation to people-trafficking or smuggling. One proposed solution is the use of stable isotope profiling (SIP) using isotope ratio mass spectrometry (IRMS). Exploiting the link between the isotopic signal of dietary components and the isotopic composition of body tissue, the aim of this study was to refine a non-invasive method of analysing human material such as scalp hair and fingernails using SIP and to assess the degree of natural variability in these profiles. Scalp hair and fingernail samples were collected from British and non-British volunteers at Queen's University Belfast every 2 weeks for a minimum of 8 months. Samples were analysed using IRMS to determine their isotopic composition for 13C, 15N, 2H and 18O. The results of this longitudinal study yielded information on the natural variability of the isotopic composition of these tissues. The data demonstrate the relatively low degree of natural variation in the 13C/15N isotopic abundance of scalp hair and fingernails whilst greater variations were recorded in the hydrogen and oxygen values of the same samples. The 15N and 18O values of nail are noticeably more variable than that of scalp hair from the same subject. A hypothesis explaining this trend is put forward based on the faster rate of formation of hair than of nails. This means that there is less time for the compounds forming hair to be affected by biochemical processes that could alter their isotopic signature.
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Affiliation(s)
- I Fraser
- Environmental Forensics and Human Health, Environmental Engineering Research Centre, Queen's University Belfast, Belfast BT9 5AG, UK.
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33
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Farmer NL, Meier-Augenstein W, Kalin RM. Stable isotope analysis of safety matches using isotope ratio mass spectrometry--a forensic case study. Rapid Commun Mass Spectrom 2005; 19:3182-6. [PMID: 16220465 DOI: 10.1002/rcm.2088] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Isotope ratio mass spectrometry (IRMS) was used to assess what contribution the technique could make towards the comparative analysis of matchstick samples within the 'normal' framework of a forensic investigation. A method was developed to allow the comparison of samples submitted as a result of an investigation, with the added advantage of rapid sample turn-around expected within this field. To the best of our knowledge this is the first time that wooden safety matches have been analysed using IRMS. In this particular case, bulk stable isotope analysis carrried out on a 'like-for-like' basis could demonstrate conclusively that matches seized from a suspect were different from those collected at the scene of crime. The maximum delta13C variability observed within one box was 2.5 per thousand, which, in conjunction with the error of measurement, was regarded to yield too wide an error margin as to permit differentiation of matchsticks based on 13C isotopic composition alone given that the 'natural' 13C abundance in wood ranges from -20 to -30 per thousand. However, from the delta2H values obtained for crime scene matches and seized matches of -114.5 per thousand and -65 per thousand, respectively, it was concluded that the matches seized were distinctly different from those collected at the crime scene.
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Affiliation(s)
- N L Farmer
- Environmental Engineering Research Centre, The Queen's University of Belfast, David Keir Building, 39-123 Stranmillis Rd., Belfast BT9 5AG, UK.
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34
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Reidy LJ, Meier-Augenstein W, Kalin RM. 13C-Isotope ratio mass spectrometry as a potential tool for the forensic analysis of white architectural paint: a preliminary study. Rapid Commun Mass Spectrom 2005; 19:1899-905. [PMID: 15945023 DOI: 10.1002/rcm.2000] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Paints have a dual role in society, to protect materials from environmental agents such as ultraviolet light, moisture and oxygen, and to make painted materials look more attractive. Variability in paint samples is often due to binder and pigment type within the sample. The most common resin used in decorative paints is drying oil alkyd resin, which incorporates soybean oil and vinyl acrylic based latexes. Traditional analytical methods used by forensic scientists may be able to say whether two paint samples are indistinguishable but cannot conclusively say that they both originate from the same source. To find out if isotopic composition can provide an added dimension of information, 28 different white architectural paints were analysed for (13)C abundance using isotope ratio mass spectrometry. In addition, variations in application, drying time and thickness were also investigated to assess the discriminatory power of (13)C data from white paints with an unknown history. Preliminary results indicate that this method could aid screening of paint samples.
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Affiliation(s)
- L J Reidy
- Environmental Engineering Research Centre, Queen's University of Belfast, David Keir Building, Stranmillis Road, Belfast BT9 5AG, UK.
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35
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Archbold ME, Redeker KR, Davis S, Elliot T, Kalin RM. A method for carbon stable isotope analysis of methyl halides and chlorofluorocarbons at pptv concentrations. Rapid Commun Mass Spectrom 2005; 19:337-342. [PMID: 15645502 DOI: 10.1002/rcm.1791] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
A pre-concentration system has been validated for use with a gas chromatography/mass spectrometry/isotope ratio mass spectrometer (GC/MS/IRMS) to determine ambient air (13)C/(12)C ratios for methyl halides (MeCl and MeBr) and chlorofluorocarbons (CFCs). The isotopic composition of specific compounds can provide useful information on their atmospheric budgets and biogeochemistry that cannot be ascertained from abundance measurements alone. Although pre-concentration systems have been previously used with a GC/MS/IRMS for atmospheric trace gas analysis, this is the first study also to report system validation tests. Validation results indicate that the pre-concentration system and subsequent separation technologies do not significantly alter the stable isotopic ratios of the target methyl halides, CFC-12 (CCl(2)F(2)) and CFC-113 (C(2)Cl(3)F(3)). Significant, but consistent, isotopic shifts of -27.5 per thousand to -25.6 per thousand do occur within the system for CFC-11 (CCl(3)F), although the shift is correctible. The method presented has the capacity to separate these target halocarbons from more than 50 other compounds in ambient air samples. Separation allows for the determination of stable carbon isotope ratios of five of these six target trace atmospheric constituents within ambient air for large volume samples (</=10 L). Representative urban air analyses from Belfast City are also presented which give carbon isotope results similar to published values for (13)C/(12)C analysis of MeCl (-39.1 per thousand) and CFC-113 (-28.1 per thousand). However, this is the first paper reporting stable carbon isotope signatures for CFC-11 (-29.4 per thousand) and CFC-12 (-37.0 per thousand).
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Affiliation(s)
- Marie E Archbold
- Environmental Engineering Research Centre, School of Civil Engineering, Queen's University of Belfast, David Keir Building, Stranmillis Rd., Belfast BT9 5AG, UK.
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Abstract
Permeable reactive barriers are a technology that is one decade old, with most full-scale applications based on abiotic mechanisms. Though there is extensive literature on engineered bioreactors, natural biodegradation potential, and in situ remediation, it is only recently that engineered passive bioreactive barrier technology is being considered at the commercial scale to manage contaminated soil and groundwater risks. Recent full-scale studies are providing the scientific confidence in our understanding of coupled microbial (and genetic), hydrogeologic, and geochemical processes in this approach and have highlighted the need to further integrate engineering and science tools.
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Affiliation(s)
- Robert M Kalin
- Environmental Engineering Research Centre, School of Civil Engineering, The Queen's University of Belfast, Belfast BT9 5AG, Northern Ireland, UK.
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Schüth C, Bill M, Barth JAC, Slater GF, Kalin RM. Carbon isotope fractionation during reductive dechlorination of TCE in batch experiments with iron samples from reactive barriers. J Contam Hydrol 2003; 66:25-37. [PMID: 14516939 DOI: 10.1016/s0169-7722(03)00026-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Reductive dechlorination of trichloroethene (TCE) by zero-valent iron produces a systematic enrichment of 13C in the remaining substrate that can be described using a Rayleigh model. In this study, fractionation factors for TCE dechlorination with iron samples from two permeable reactive barriers (PRBs) were established in batch experiments. Samples included original unused iron as well as material from a barrier in Belfast after almost 4 years of operation. Despite the variety of samples, carbon isotope fractionations of TCE were remarkably similar and seemed to be independent of iron origin, reaction rate, and formation of precipitates on the iron surfaces. The average enrichment factor for all experiments was -10.1 per thousand (+/- 0.4 per thousand). These results indicate that the enrichment factor provides a powerful tool to monitor the reaction progress, and thus the performance, of an iron-reactive barrier over time. The strong fractionation observed may also serve as a tool to distinguish between insufficient residence time in the wall and a possible bypassing of the wall by the plume, which should result in an unchanged isotopic signature of the TCE. Although further work is necessary to apply this stable isotope method in the field, it has potential to serve as a unique monitoring tool for PRBs based on zero-valent iron.
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Affiliation(s)
- Christoph Schüth
- Applied Geology Group, Department of Applied Geology, Geological Institute, University of Tübingen, Sigwartstr. 10, Tübingen D-72076, Germany.
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Yang YS, McGeough KL, Kalin RM, Dickson KW. Numerical modeling for remediation of contaminated land and groundwater. Bull Environ Contam Toxicol 2003; 71:729-736. [PMID: 14672125 DOI: 10.1007/s00128-003-0193-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Affiliation(s)
- Y S Yang
- School of Civil Engineering, Queen's University Belfast, Belfast BT7 1NN, United Kingdom
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Zhao L, Yang YS, Tan X, Kalin RM. Removal of nitrate contaminant in porous media aquifer through microbiological method. Bull Environ Contam Toxicol 2003; 71:362-369. [PMID: 14560389 DOI: 10.1007/s00128-003-0172-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Affiliation(s)
- L Zhao
- School of Environmental Science and Engineering, Tianjin University, Tianjin 300072, People's Republic of China
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40
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Abstract
Atmospheric chloromethane (CH3Cl) plays an important role in stratospheric ozone destruction, but many uncertainties exist regarding the strengths of its sources and sinks and particularly regarding the processes generating this naturally occurring gas. Evidence is presented here that CH3Cl is produced in many terrestrial environments by a common mechanism. Abiotic conversion of chloride to CH3Cl occurs readily in plant material, with the widespread plant component pectin acting as a methyl donor. Significant CH3Cl emissions from senescent and dead leaves were observed at ambient temperatures; those emissions rose dramatically when temperatures increased. This ubiquitous process acting in terrestrial ecosystems and during biomass burning could contribute the bulk of atmospheric CH3Cl.
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Affiliation(s)
- John T G Hamilton
- Department of Agriculture and Rural Development for Northern Ireland, Newforge Lane, Belfast BT9 5PX, UK.
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41
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Ferguson AS, Doherty R, Larkin MJ, Kalin RM, Irvine V, Ofterdinger US. Toxicity assessment of a former manufactured gas plant. Bull Environ Contam Toxicol 2003; 71:21-30. [PMID: 12945837 DOI: 10.1007/s00128-003-0125-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Affiliation(s)
- A S Ferguson
- QUESTOR Centre, Queens University Belfast, David Keir Building, Stranmillis Road, Belfast, BT9 5AG, United Kingdom
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Harper DB, Hamilton JTG, Ducrocq V, Kennedy JT, Downey A, Kalin RM. The distinctive isotopic signature of plant-derived chloromethane: possible application in constraining the atmospheric chloromethane budget. Chemosphere 2003; 52:433-436. [PMID: 12738266 DOI: 10.1016/s0045-6535(03)00206-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Chloromethane (CH(3)Cl) is the most abundant halocarbon in the atmosphere. Although largely of natural origin it is responsible for around 17% of chlorine-catalysed ozone destruction. Sources identified to date include biomass burning, oceanic emissions, wood-rotting fungi, higher plants and most recently tropical ferns. Current estimates reveal a shortfall of around 2 million ty(-1) in sources versus sinks for the halocarbon. It is possible that emissions from green plants have been substantially underestimated. A potentially valuable tool for validating emission flux estimates is comparison of the delta13C value of atmospheric CH(3)Cl with those of CH(3)Cl from the various sources. Here we report delta13C values for CH(3)Cl released by two species of tropical ferns and show that the isotopic signature of CH(3)Cl from pteridophytes like that of CH(3)Cl from higher plants is quite different from that of CH(3)Cl produced by biomass burning, fungi and industry. delta13C values for CH(3)Cl produced by Cyathea smithii and Angiopteris evecta were respectively -72.7 per thousand and -69.3 per thousand representing depletions relative to plant biomass of 42.3 per thousand and 43.4 per thousand. The characteristic isotopic signature of CH(3)Cl released by green plants should help constrain their contribution to the atmospheric burden when reliable delta13C values for all other major sources of CH(3)Cl are obtained and a globally averaged delta13C value for atmospheric CH(3)Cl is available.
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Affiliation(s)
- D B Harper
- School of Agriculture and Food Science, The Queen's University of Belfast, Newforge Lane, Belfast BT9 5PX, UK.
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Abstract
The occurrence of the fuel oxygenate methyl tert-butyl ether (MTBE) in the environment has received considerable scientific attention. The pollutant is frequently found in the groundwater due to leaking of underground storage tanks or pipelines. Concentrations of more than several mg/L MTBE were detected in groundwater at several places in the US and Germany in the last few years. In situ chemical oxidation is a promising treatment method for MTBE-contaminated plumes. This research investigated the reaction kinetics for the oxidation of MTBE by permanganate. Batch tests demonstrated that the oxidation of MTBE by permanganate is second order overall and first order individually with respect to permanganate and MTBE. The second-order rate constant was 1.426 x 10(-6) L/mg/h. The influence of pH on the reaction rate was demonstrated to have no significant effect. However, the rate of MTBE oxidation by potassium permanganate is 2-3 orders of magnitude lower than of other advanced oxidation processes. The slower rates of MTBE oxidation by permanganate limit the applicability of this process for rapid MTBE cleanup strategies. However, permanganate oxidation of MTBE has potential for passive oxidation risk management strategies.
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Affiliation(s)
- Jochen H Damm
- School of Civil Engineering, Queen's University of Belfast, UK.
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Barth JAC, Slater G, Schüth C, Bill M, Downey A, Larkin M, Kalin RM. Carbon isotope fractionation during aerobic biodegradation of trichloroethene by Burkholderia cepacia G4: a tool to map degradation mechanisms. Appl Environ Microbiol 2002; 68:1728-34. [PMID: 11916690 PMCID: PMC123882 DOI: 10.1128/aem.68.4.1728-1734.2002] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The strain Burkholderia cepacia G4 aerobically mineralized trichloroethene (TCE) to CO(2) over a time period of approximately 20 h. Three biodegradation experiments were conducted with different bacterial optical densities at 540 nm (OD(540)s) in order to test whether isotope fractionation was consistent. The resulting TCE degradation was 93, 83.8, and 57.2% (i.e., 7.0, 16.2, and 42.8% TCE remaining) at OD(540)s of 2.0, 1.1, and 0.6, respectively. ODs also correlated linearly with zero-order degradation rates (1.99, 1.11, and 0.64 micromol h(-1)). While initial nonequilibrium mass losses of TCE produced only minor carbon isotope shifts (expressed in per mille delta(13)C(VPDB)), they were 57.2, 39.6, and 17.0 per thousand between the initial and final TCE levels for the three experiments, in decreasing order of their OD(540)s. Despite these strong isotope shifts, we found a largely uniform isotope fractionation. The latter is expressed with a Rayleigh enrichment factor, epsilon, and was -18.2 when all experiments were grouped to a common point of 42.8% TCE remaining. Although, decreases of epsilon to -20.7 were observed near complete degradation, our enrichment factors were significantly more negative than those reported for anaerobic dehalogenation of TCE. This indicates typical isotope fractionation for specific enzymatic mechanisms that can help to differentiate between degradation pathways.
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Affiliation(s)
- Johannes A C Barth
- Scottish Universities Environmental Research Centre, East Kilbride, Glasgow G75 0QF, Scotland.
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Harper DB, Kalin RM, Hamilton JT, Lamb C. Carbon isotope ratios for chloromethane of biological origin: potential tool in determining biological emissions. Environ Sci Technol 2001; 35:3616-3619. [PMID: 11783636 DOI: 10.1021/es0106467] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Chloromethane (CH3Cl) with a global atmospheric burden of 5.3 million t is the most abundant halocarbon in the atmosphere. However, the origin of ca. 50% of the estimated annual global input of 4 million t of the gas to the atmosphere has yet to be determined. As the oceanic contribution to the global CH3Cl flux is now tightly constrained, an important terrestrial source is either underestimated or unrecognized. It has recently been proposed that higher plants may represent a CH3Cl source of sufficient magnitude to resolve the global budget imbalance. A potentially useful tool in validating CH3Cl emission flux estimates is comparison of the carbon isotope ratio of atmospheric CH3Cl with those of CH3Cl originating from various sources. Here we report the first measurements of delta13C for CH3Cl produced biologically. The CH3Cl released by the higher plant species Batis maritima and Solanum tuberosum was dramatically depleted in 13C with respect to plant tissue (delta13C = -36.8/1000 and -34.5/1000, respectively); CH3Cl released by the fungus Phellinus pomaceus also showed significant 13C depletion with respect to the wood growth substrate (delta13C = -17.9/1000). When reliable delta13C values for the other major sources of atmospheric CH3Cl become available, the distinctive isotopic signature of plant-derived CH3Cl should help constrain the contribution to the atmospheric burden from this source.
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Affiliation(s)
- D B Harper
- Microbial Biochemistry Section, School of Agriculture and Food Science, The Queen's University of Belfast, UK.
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46
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Abstract
Dehalogenation of trichloroethene (TCE) in the aqueous phase, either on palladium catalysts with hydrogen as the reductant or on metallic iron, was associated with strong changes in delta13C. In general, the delta13C of product phases were more negative than those of the parent compound and were enriched with time and fraction of TCE remaining. For dehalogenation with iron, the delta13C of TCE and products varied from -42/1000 to +5/1000. For the palladium experiments, the final product, ethane, reached the initial delta13C of TCE at completion of the dehalogenation reaction. During dehalogenation, the carbon isotope fractionation between TCE and product phases was not constant. The variation in delta13C of TCE and products offers a new monitoring tool that operates independently of the initial concentration of pollutants for abiotic degradation processes of TCE in the subsurface, and may be useful for evaluation of remediation efficiency.
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Affiliation(s)
- M Bill
- Applied Geology Group, Geological Institute, University of Tübingen, Germany
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Abstract
Gas-phase photocatalysis of 1,4-dichlorobut-2-enes and 3,4-dichlorobut-1-ene (DCB) has been studied using TiO2 and 3% WO3/TiO2 supported on SiO2. DCB was found to oxidize efficiently over these catalysts; however, only low rates of CO2 formation were observed. With these chlorinated hydrocarbons, the catalysts were found to deactivate over time, probably via the formation of aldol condensation products of chloracetaldehyde, which is the predominant intermediate observed. The variation in rate and selectivity of the oxidation reactions with O2 concentration is reported and a mechanism is proposed. Using isotope ratio mass spectrometry, the initial step for the DCB removal has been shown not to be a carbon bond cleavage but is likely to be hydroxyl radical addition to the carbon-carbon double bond.
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Affiliation(s)
- N A Hamill
- School of Chemistry, David Keir Building, Queen's University of Belfast, Belfast BT9 5AG, Northern Ireland, U.K
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McConville C, Kalin RM, Johnston H, McNeill GW. Evaluation of recharge in a small temperate catchment using natural and applied delta 18O profiles in the unsaturated zone. Ground Water 2001; 39:616-23. [PMID: 11447861 DOI: 10.1111/j.1745-6584.2001.tb02349.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/16/2023]
Abstract
A water balance study was used for determining recharge rate and mechanisms in the Enler Catchment, Northern Ireland. Here spatially limited data for the water balance resulted in varied calculation of the annual and monthly net infiltration rate. This paper outlines a method whereby high-resolution soil profiles (1 to 2 cm) were obtained from field cores in the upper 2 m of the unsaturated zone using delta 18O of water. These profiles show changes in isotopic composition that range from individual rainfall events to annually integrated cycles of rainfall. Recharge rates were calculated from stable isotope profiles for each of the four main soil types in the study catchment and summed over each area resulting in an average recharge in the range 55 to 70 mm/a, which is comparable with previous findings. Applied isotopic tracer tests were also conducted to evaluate the extent of preferential flow through the two main soil types in the catchment. Rates of water movement found from these experiments show good agreement with natural isotopic profiles; however, evidence suggests that preferential flow is not the dominant process controlling water movement in this catchment. This type of data provides valuable information about recharge rates and mechanisms and may facilitate better prediction of contaminant transport pathways in the vadose zone.
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Affiliation(s)
- C McConville
- Environmental Engineering Research Centre, School of Civil Engineering, Queen's University of Belfast, Belfast, Northern Ireland, BT7 1NN.
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Miller LG, Kalin RM, McCauley SE, Hamilton JT, Harper DB, Millet DB, Oremland RS, Goldstein AH. Large carbon isotope fractionation associated with oxidation of methyl halides by methylotrophic bacteria. Proc Natl Acad Sci U S A 2001; 98:5833-7. [PMID: 11344313 PMCID: PMC33299 DOI: 10.1073/pnas.101129798] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2000] [Accepted: 03/13/2001] [Indexed: 11/18/2022] Open
Abstract
The largest biological fractionations of stable carbon isotopes observed in nature occur during production of methane by methanogenic archaea. These fractionations result in substantial (as much as approximately 70 per thousand) shifts in delta(13)C relative to the initial substrate. We now report that a stable carbon isotopic fractionation of comparable magnitude (up to 70 per thousand) occurs during oxidation of methyl halides by methylotrophic bacteria. We have demonstrated biological fractionation with whole cells of three methylotrophs (strain IMB-1, strain CC495, and strain MB2) and, to a lesser extent, with the purified cobalamin-dependent methyltransferase enzyme obtained from strain CC495. Thus, the genetic similarities recently reported between methylotrophs, and methanogens with respect to their pathways for C(1)-unit metabolism are also reflected in the carbon isotopic fractionations achieved by these organisms. We found that only part of the observed fractionation of carbon isotopes could be accounted for by the activity of the corrinoid methyltransferase enzyme, suggesting fractionation by enzymes further along the degradation pathway. These observations are of potential biogeochemical significance in the application of stable carbon isotope ratios to constrain the tropospheric budgets for the ozone-depleting halocarbons, methyl bromide and methyl chloride.
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Affiliation(s)
- L G Miller
- United States Geological Survey, Menlo Park, CA 94025, USA.
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50
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Kalin RM, Hamilton JT, Harper DB, Miller LG, Lamb C, Kennedy JT, Downey A, McCauley S, Goldstein AH. Continuous flow stable isotope methods for study of delta(13)C fractionation during halomethane production and degradation. Rapid Commun Mass Spectrom 2001; 15:357-363. [PMID: 11241767 DOI: 10.1002/rcm.219] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Gas chromatography/mass spectrometry/isotope ratio mass spectrometry (GC/MS/IRMS) methods for delta(13)C measurement of the halomethanes CH(3)Cl, CH(3)Br, CH(3)I and methanethiol (CH(3)SH) during studies of their biological production, biological degradation, and abiotic reactions are presented. Optimisation of gas chromatographic parameters allowed the identification and quantification of CO(2), O(2), CH(3)Cl, CH(3)Br, CH(3)I and CH(3)SH from a single sample, and also the concurrent measurement of delta(13)C for each of the halomethanes and methanethiol. Precision of delta(13)C measurements for halomethane standards decreased (+/-0.3, +/-0.5 and +/-1.3 per thousand) with increasing mass (CH(3)Cl, CH(3)Br, CH(3)I, respectively). Given that carbon isotope effects during biological production, biological degradation and some chemical (abiotic) reactions can be as much as 100 per thousand, stable isotope analysis offers a precise method to study the global sources and sinks of these halogenated compounds that are of considerable importance to our understanding of stratospheric ozone destruction.
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Affiliation(s)
- R M Kalin
- Environmental Engineering Research Centre, School of Civil Engineering, The Queen's University of Belfast, Belfast BT9 5AG, UK.
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