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Liu G, Frankó B, Strömberg S, Zheng D, Nistor M, Liu J, Deng L. Impact of atmospheric pressure variations on aerobic biodegradation test. WASTE MANAGEMENT & RESEARCH : THE JOURNAL OF THE INTERNATIONAL SOLID WASTES AND PUBLIC CLEANSING ASSOCIATION, ISWA 2023; 41:1559-1569. [PMID: 37029528 DOI: 10.1177/0734242x231164320] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
Biodegradation rate is an important index to evaluate the environmental risk of chemicals, which is usually determined by measuring oxygen consumption through respirometer in a biodegradation test. However, atmospheric pressure variations affect reactor oxygen concentration and oxygen volume recorded by respirometer in biodegradation test, and the parameters of reactor volume and test material amount amplify its effect. Atmospheric pressure variation >1 kPa could introduce >20% underestimation in biodegradation rate when a small amount of test material (0.04-0.2 g per 100 g of inoculum) and high reactor volume (2-4 L) were used according to the international standards. A 5 kPa drop in atmospheric pressure leads to a 6% decrease in headspace oxygen concentration in the reactor, which could subsequently inhibit biodegradation microbials and decrease the biodegradation rate by 30%. Moreover, the biodegradation process (oxygen consumption rate) could be accelerated/delayed several times by atmospheric pressure variations compared to the process without variations when the oxygen consumption rate was <5 mL h-1 in a 0.5 or 1 L reactor and <10 mL h-1 in a 2-L reactor. Mitigating the effects of atmospheric pressure variations on biodegradation test includes lowering the reactor volume, increasing the test material amount and recording atmospheric pressure for further modification.
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Affiliation(s)
- Gangjin Liu
- Biogas Institute of Ministry of Agriculture and Rural Affairs, Chengdu, China
- Division of Biotechnology, Department of Chemistry, Lund University, Lund, Sweden
| | - Balázs Frankó
- Division of Biotechnology, Department of Chemistry, Lund University, Lund, Sweden
| | | | - Dan Zheng
- Biogas Institute of Ministry of Agriculture and Rural Affairs, Chengdu, China
| | | | - Jing Liu
- Division of Biotechnology, Department of Chemistry, Lund University, Lund, Sweden
- BPC Instruments AB, Lund, Sweden
| | - Liangwei Deng
- Biogas Institute of Ministry of Agriculture and Rural Affairs, Chengdu, China
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2
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Unnithan A, Bekele DN, Chadalavada S, Naidu R. Insights into vapour intrusion phenomena: Current outlook and preferential pathway scenario. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 796:148885. [PMID: 34265614 DOI: 10.1016/j.scitotenv.2021.148885] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2021] [Revised: 06/14/2021] [Accepted: 07/03/2021] [Indexed: 06/13/2023]
Abstract
Vapour intrusion (VI) is the phenomenon by which volatile organic compounds (VOCs) migrate from the subsurface source through the soil and enter into the overlying buildings, affecting the indoor air quality and ultimately causing health hazards to the occupants. Health risk assessments associated with hydrocarbon contaminated sites and recommendations of site closure are often made by quantifying the VI risks using mathematical models known as 'vapour intrusion models' (VIM). In order to predict the health risk, various factors such as the lithological and geochemical conditions of the subsurface, environmental conditions, building operational conditions etc. are commonly evaluated using VIMs. Use of these models can overlook the role of preferential pathways like highly permeable subsurface layers and utility lines which act as the path of least resistance for vapour transport, which can increase the VI risks. The extensive networks of utility lines and sanitary sewer systems in urban areas can significantly exacerbate the uncertainty of VI investigations. The backfill materials like sand and gravel surrounding the utility lines can allow the vapours to easily pass through due to their high porosity as compared to natural formations. Hence, failure to understand the role of preferential pathways on the fate and transport of VOC in the vadose zone can result in more conservative predictions of indoor air vapour concentrations and wrong clean up approaches. This comprehensive review outlines the vapour transport mechanisms, factors influencing VI, VIMs and the role of preferential pathways in predicting indoor air vapour concentrations.
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Affiliation(s)
- Aravind Unnithan
- Global Centre for Environmental Remediation, The University of Newcastle, University Dr, Callaghan, NSW 2308, Australia
| | - Dawit Nega Bekele
- Global Centre for Environmental Remediation, The University of Newcastle, University Dr, Callaghan, NSW 2308, Australia; CRC CARE, ATC Building, The University of Newcastle, University Dr, Callaghan, NSW 2308, Australia
| | - Sreenivasulu Chadalavada
- Global Centre for Environmental Remediation, The University of Newcastle, University Dr, Callaghan, NSW 2308, Australia; CRC CARE, ATC Building, The University of Newcastle, University Dr, Callaghan, NSW 2308, Australia
| | - Ravi Naidu
- Global Centre for Environmental Remediation, The University of Newcastle, University Dr, Callaghan, NSW 2308, Australia; CRC CARE, ATC Building, The University of Newcastle, University Dr, Callaghan, NSW 2308, Australia.
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BenIsrael M, Wanner P, Fernandes J, Burken JG, Aravena R, Parker BL, Haack EA, Tsao DT, Dunfield KE. Quantification of toluene phytoextraction rates and microbial biodegradation functional profiles at a fractured bedrock phytoremediation site. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 707:135890. [PMID: 31865073 DOI: 10.1016/j.scitotenv.2019.135890] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2019] [Revised: 11/27/2019] [Accepted: 11/30/2019] [Indexed: 05/28/2023]
Abstract
This field study evaluated the efficacy of a mature hybrid poplar phytoremediation system for the remediation of toluene in a fractured bedrock aquifer site. Phytoextraction activity of the trees and the ecology and biodegradation potential of root-colonizing bacteria that ultimately influence how much toluene is transported from the roots and phytoextracted to the aboveground point of measurement were explored. Peak-season toluene mass removal rates ranging from 313 to 743 μg/day were quantified using passive in planta contaminant sampling techniques and continuous heat dissipation transpiration measurements in tree stems. Root bacterial microbiome structure and biodegradation potential were evaluated via high-throughput sequencing and predictive metagenomic functional modelling of bacterial 16S rRNA genes in roots. Poplar roots were colonized mostly by Proteobacteria, Actinobacteria, and Bacteroidetes. Distinct, more uniform communities were observed in roots associated with trees planted in the toluene source area compared to other areas, with differences apparent at lower taxonomic levels. Significant enrichment of Streptomyces in roots was observed in the source area, implicating that genus as a potentially important poplar endophyte at toluene-impacted sites. Moreover, significantly greater aerobic toluene biodegradation capacity was predicted in these roots compared to other areas using taxonomic functional modelling. Together with passive sampling, the molecular results provided supporting evidence of biodegradation activity in the source area and contextualized the detected phytoextraction patterns. These results support the application of phytoremediation systems for aromatic hydrocarbons in environments with complex geology and demonstrate field-validated monitoring techniques to assess phytoextraction and biodegradation in these systems.
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Affiliation(s)
- Michael BenIsrael
- School of Environmental Sciences, University of Guelph, 50 Stone Road East, Guelph, ON N1G 2W1, Canada
| | - Philipp Wanner
- G(360) Institute for Groundwater Research, University of Guelph, 50 Stone Road East, Guelph, ON N1G 2W1, Canada
| | - Jeremy Fernandes
- G(360) Institute for Groundwater Research, University of Guelph, 50 Stone Road East, Guelph, ON N1G 2W1, Canada
| | - Joel G Burken
- Civil, Architectural and Environmental Engineering, Missouri University of Science and Technology, 1401 N. Pine St., Rolla, MO 65409-0030, USA
| | - Ramon Aravena
- Department of Earth and Environmental Sciences, University of Waterloo, 200 University Avenue West, Waterloo, ON N2L 3G1, Canada
| | - Beth L Parker
- G(360) Institute for Groundwater Research, University of Guelph, 50 Stone Road East, Guelph, ON N1G 2W1, Canada
| | - Elizabeth A Haack
- EcoMetrix Inc., 6800 Campobello Road, Mississauga, ON L5N 2L8, Canada
| | - David T Tsao
- BP Corporation North America Inc., 150 W Warrenville Road #605-2E, Naperville, IL 60563, USA
| | - Kari E Dunfield
- School of Environmental Sciences, University of Guelph, 50 Stone Road East, Guelph, ON N1G 2W1, Canada.
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Reichman R, Shirazi E, Colliver DG, Pennell KG. US residential building air exchange rates: new perspectives to improve decision making at vapor intrusion sites. ENVIRONMENTAL SCIENCE. PROCESSES & IMPACTS 2017; 19:87-100. [PMID: 28186210 PMCID: PMC5369024 DOI: 10.1039/c6em00504g] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Vapor intrusion (VI) is well-known to be difficult to characterize because indoor air (IA) concentrations exhibit considerable temporal and spatial variability in homes throughout impacted communities. To overcome this and other limitations, most VI science has focused on subsurface processes; however there is a need to understand the role of aboveground processes, especially building operation, in the context of VI exposure risks. This tutorial review focuses on building air exchange rates (AERs) and provides a review of literature related building AERs to inform decision making at VI sites. Commonly referenced AER values used by VI regulators and practitioners do not account for the variability in AER values that have been published in indoor air quality studies. The information presented herein highlights that seasonal differences, short-term weather conditions, home age and air conditioning status, which are well known to influence AERs, are also likely to influence IA concentrations at VI sites. Results of a 3D VI model in combination with relevant AER values reveal that IA concentrations can vary more than one order of magnitude due to air conditioning status and one order of magnitude due to house age. Collectively, the data presented strongly support the need to consider AERs when making decisions at VI sites.
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Affiliation(s)
- Rivka Reichman
- University of Kentucky, Department of Civil Engineering, Lexington, KY 40506, USA.
| | - Elham Shirazi
- University of Kentucky, Department of Civil Engineering, Lexington, KY 40506, USA.
| | - Donald G Colliver
- University of Kentucky, Department of Biosystems and Agricultural Engineering, Lexington, KY 40503, USA
| | - Kelly G Pennell
- University of Kentucky, Department of Civil Engineering, Lexington, KY 40506, USA.
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Yao Y, Yang F, Suuberg EM, Provoost J, Liu W. Estimation of contaminant subslab concentration in petroleum vapor intrusion. JOURNAL OF HAZARDOUS MATERIALS 2014; 279:336-47. [PMID: 25124892 PMCID: PMC4342259 DOI: 10.1016/j.jhazmat.2014.05.065] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2014] [Revised: 04/29/2014] [Accepted: 05/22/2014] [Indexed: 05/22/2023]
Abstract
In this study, the development and partial validation are presented for an analytical approximation method for prediction of subslab contaminant concentrations in PVI. The method involves combining an analytic approximation to soil vapor transport with a piecewise first-order biodegradation model (together called the Analytic Approximation Method, including Biodegradation, AAMB), the result of which calculation provides an estimate of contaminant subslab concentrations, independent of building operation conditions. Comparisons with three-dimensional (3-D) simulations and another PVI screening tool, BioVapor, show that the AAMB is suitable for application in a scenario involving a building with an impermeable foundation surrounded by open ground surface, where the atmosphere is regarded as the primary oxygen source. Predictions from the AAMB can be used to determine the required vertical source-building separation, given a subslab screening concentration, allowing identification of buildings at risk for PVI. This equation shows that the "vertical screening distance" suggested by U.S. EPA is sufficient in most cases, as long as the total petroleum hydrocarbon (TPH) soil gas concentration at the vapor source does not exceed 50-100mg/L. When the TPH soil gas concentration of the vapor source approaches a typical limit, i.e. 400mg/L, the "vertical screening distance" required would be much greater.
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Affiliation(s)
- Yijun Yao
- MOE Key Lab of Environmental Remediation and Ecosystem Health, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058, China; Research Center for Air Pollution and Health, Zhejiang University, Hangzhou 310058, China; Institute of Environmental Science, Zhejiang University, Hangzhou 310058, China.
| | - Fangxing Yang
- MOE Key Lab of Environmental Remediation and Ecosystem Health, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058, China; Research Center for Air Pollution and Health, Zhejiang University, Hangzhou 310058, China; Institute of Environmental Science, Zhejiang University, Hangzhou 310058, China
| | | | | | - Weiping Liu
- MOE Key Lab of Environmental Remediation and Ecosystem Health, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058, China; Research Center for Air Pollution and Health, Zhejiang University, Hangzhou 310058, China; Institute of Environmental Science, Zhejiang University, Hangzhou 310058, China
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Shen R, Suuberg EM. Analytical Quantification of the Subslab Volatile Organic Vapor Concentration from a Non-uniform Source. ENVIRONMENTAL MODELLING & SOFTWARE : WITH ENVIRONMENT DATA NEWS 2014; 54:1-8. [PMID: 24639604 PMCID: PMC3951510 DOI: 10.1016/j.envsoft.2013.12.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
The transport of volatile organic vapors from subsurface to building involves complex processes. Since the release of the draft subsurface vapor intrusion guidance by the U.S. EPA in 2002, great progress has been made in understanding these processes in various field and modeling studies. In these studies, the importance of analyzing and predicting the subslab volatile organic vapor concentration was noted. To quantitatively predict subslab vapor concentration is, however, complicated, especially for sites located over non-uniform vapor sources. This manuscript provides a method to estimate the vapor concentration beneath the subslab using a closed-form analytical solution that can approximate full three-dimensional modeling results, but does not require the use of advanced numerical simulation. This method allows prediction of the subslab vapor concentration profile beneath the slab for various source configurations, given inputs of building slab dimension and source depth. The interaction of the influences of non-uniform source and the slab capping effect on the subslab vapor concentration is addressed.
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Affiliation(s)
- Rui Shen
- Corresponding author phone: (401) 863-1420; , or
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