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Pedregal-Montes A, Jennings E, Kothawala D, Jones K, Sjöstedt J, Langenheder S, Marcé R, Farré MJ. Disinfection by-product formation potential in response to variability in dissolved organic matter and nutrient inputs: Insights from a mesocosm study. WATER RESEARCH 2024; 258:121791. [PMID: 38830291 DOI: 10.1016/j.watres.2024.121791] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/05/2024] [Revised: 05/10/2024] [Accepted: 05/14/2024] [Indexed: 06/05/2024]
Abstract
Changes in rainfall patterns driven by climate change affect the transport of dissolved organic matter (DOM) and nutrients through runoff to freshwater systems. This presents challenges for drinking water providers. DOM, which is a heterogeneous mix of organic molecules, serves as a critical precursor for disinfection by-products (DBPs) which are associated with adverse health effects. Predicting DBP formation is complex due to changes in DOM concentration and composition in source waters, intensified by altered rainfall frequency and intensity. We employed a novel mesocosm approach to investigate the response of DBP precursors to variability in DOM composition and inorganic nutrients, such as nitrogen and phosphorus, export to lakes. Three distinct pulse event scenarios, mimicking extreme, intermittent, and continuous runoff were studied. Simultaneous experiments were conducted at two boreal lakes with distinct DOM composition, as reflected in their color (brown and clear lakes), and bromide content, using standardized methods. Results showed primarily site-specific changes in DBP precursors, some heavily influenced by runoff variability. Intermittent and daily pulse events in the clear-water mesocosms exhibited higher haloacetonitriles (HANs) formation potential linked to freshly produced protein-like DOM enhanced by light availability. In contrast, trihalomethanes (THMs), associated with humic-like DOM, showed no significant differences between pulse events in the brown-water mesocosms. Elevated bromide concentration in the clear mesocosms critically influenced THMs speciation and concentrations. These findings contribute to understanding how changing precipitation patterns impact the dynamics of DBP formation, thereby offering insights for monitoring the mobilization and alterations of DBP precursors within catchment areas and lake ecosystems.
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Affiliation(s)
- Angela Pedregal-Montes
- Catalan Institute for Water Research (ICRA), Carrer Emili Grahit 101, Parc Científic i Tecnològic de la Universitat de Girona, 17003 Girona, Spain; University of Girona, Plaça de Sant Domènec 3, 17004 Girona, Spain.
| | - Eleanor Jennings
- Centre for Freshwater and Environmental Studies, Dundalk Institute of Technology, A91 K584 Dundalk, Ireland
| | - Dolly Kothawala
- Department of Ecology and Genetics/Limnology, Uppsala University, SE-75236 Uppsala, Sweden
| | - Kevin Jones
- Department of Biology, Aquatic Ecology, Lund University, Lund, Sweden
| | - Johanna Sjöstedt
- Department of Biology, Aquatic Ecology, Lund University, Lund, Sweden; School of Business, Innovation and Sustainability, Halmstad University, Halmstad, Sweden
| | - Silke Langenheder
- Department of Ecology and Genetics/Limnology, Uppsala University, SE-75236 Uppsala, Sweden
| | - Rafael Marcé
- Centre for Advanced Studies of Blanes (CEAB), Spanish National Research Council (CSIC), 17300 Blanes, Spain
| | - Maria José Farré
- Catalan Institute for Water Research (ICRA), Carrer Emili Grahit 101, Parc Científic i Tecnològic de la Universitat de Girona, 17003 Girona, Spain; University of Girona, Plaça de Sant Domènec 3, 17004 Girona, Spain.
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2
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Nakhavali MA, Lauerwald R, Regnier P, Friedlingstein P. Historical trends and drivers of the laterally transported terrestrial dissolved organic carbon to river systems. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 917:170560. [PMID: 38301790 DOI: 10.1016/j.scitotenv.2024.170560] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2023] [Revised: 01/26/2024] [Accepted: 01/28/2024] [Indexed: 02/03/2024]
Abstract
Dissolved organic carbon (DOC) represents a critical component of terrestrial carbon (C) cycling and is a key contributor to the carbon flux between land and aquatic systems. Historically, the quantification of environmental factors influencing DOC leaching has been underexplored, with a predominant focus on land use changes as the main driver. In this study, the process-based terrestrial ecosystem model JULES-DOCM was utilized to simulate the spatiotemporal patterns of DOC leaching into the global river network from 1860 to 2010. This study reveals a 17 % increment in DOC leaching to rivers, reaching 292 Tg C yr-1 by 2010, with atmospheric CO2 fertilization identified as the primary controlling factor, significantly enhancing DOC production and leaching following increased vegetation productivity and soil carbon stocks. To specifically quantify the contribution of CO2 fertilization, a factorial simulation approach was employed that isolated the effects of CO2 from other potential drivers of change. The research highlights distinct regional responses. While globally CO2 fertilization is the dominant factor, in boreal regions, climate change markedly influences DOC dynamics, at times exceeding the impact of CO2. Temperate and sub-tropical areas exhibit similar trends in DOC leaching, largely controlled by CO2 fertilization, while climate change showed an indirect effect through modifications in runoff patterns. In contrast, the tropics show a relatively low increase in DOC leaching, which can be related to alterations in soil moisture and temperature. Additionally, the study re-evaluates the role of land use change in DOC leaching, finding its effect to be considerably smaller than previously assumed. These insights emphasize the dominant roles of CO2 fertilization and climate change in modulating DOC leaching, thereby refining our understanding of terrestrial carbon dynamics and their broader implications on the global C budget.
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Affiliation(s)
| | - Ronny Lauerwald
- Université Paris-Saclay, INRAE, AgroParisTech, UMR ECOSYS, 78850 Thiverval-Grignon, France
| | - Pierre Regnier
- Biogeochemistry and Modelling of the Earth System, Department Geoscience, Environment and Society, Université Libre de Bruxelles, Bruxelles, Belgium
| | - Pierre Friedlingstein
- LMD/IPSL, ENS, PSL Université, École Polytechnique, Institut Polytechnique de Paris, Sorbonne Université, CNRS, Paris, France; University of Exeter, College of Engineering, Mathematics and Physical Sciences, Exeter EX4 4QE, UK
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Anderson LE, DeMont I, Dunnington DD, Bjorndahl P, Redden DJ, Brophy MJ, Gagnon GA. A review of long-term change in surface water natural organic matter concentration in the northern hemisphere and the implications for drinking water treatment. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 858:159699. [PMID: 36306839 DOI: 10.1016/j.scitotenv.2022.159699] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2022] [Revised: 10/20/2022] [Accepted: 10/20/2022] [Indexed: 06/16/2023]
Abstract
Reduced atmospheric acid deposition has given rise to recovery from acidification - defined as increasing pH, acid neutralization capacity (ANC), or alkalinity in surface waters. Strong evidence of recovery has been reported across North America and Europe, driving chemical responses. The primary chemical responses identified in this review were increasing concentration and changing character of natural organic matter (NOM) towards predominantly hydrophobic nature. The concentration of NOM also influenced trace metal cycling as many browning surface waters also reported increases in Fe and Al. Further, climate change and other factors (e.g., changing land use) act in concert with reductions in atmospheric deposition to contribute to widespread browning and will have a more pronounced effect as deposition stabilizes. The observed water quality trends have presented challenges for drinking water treatment (e.g., increased chemical dosing, poor filter operations, formation of disinfection by-products) and many facilities may be under designed as a result. This comprehensive review has identified key research areas to be addressed, including 1) a need for comprehensive monitoring programs (e.g., larger timescales; consistency in measurements) to assess climate change impacts on recovery responses and NOM dynamics, and 2) a better understanding of drinking water treatment vulnerabilities and the transition towards robust treatment technologies and solutions that can adapt to climate change and other drivers of changing water quality.
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Affiliation(s)
- Lindsay E Anderson
- Centre for Water Resources Studies, Department of Civil & Resource Engineering, Dalhousie University, 1360 Barrington St. Halifax, Nova Scotia, Canada.
| | - Isobel DeMont
- Centre for Water Resources Studies, Department of Civil & Resource Engineering, Dalhousie University, 1360 Barrington St. Halifax, Nova Scotia, Canada
| | - Dewey D Dunnington
- Centre for Water Resources Studies, Department of Civil & Resource Engineering, Dalhousie University, 1360 Barrington St. Halifax, Nova Scotia, Canada
| | - Paul Bjorndahl
- Department of Mathematics & Statistics, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Dave J Redden
- Centre for Water Resources Studies, Department of Civil & Resource Engineering, Dalhousie University, 1360 Barrington St. Halifax, Nova Scotia, Canada
| | | | - Graham A Gagnon
- Centre for Water Resources Studies, Department of Civil & Resource Engineering, Dalhousie University, 1360 Barrington St. Halifax, Nova Scotia, Canada
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Liu W, Wang Z, Li R, Wu T. A bibliometric analysis of mountain ecosystem services, 2000-2019. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2022; 29:16633-16652. [PMID: 34651277 DOI: 10.1007/s11356-021-16766-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2021] [Accepted: 09/23/2021] [Indexed: 06/13/2023]
Abstract
Research on mountain ecosystem services (MES) under the influence of climate change and human activities has gradually become the focus of academic attention in recent years. Here, this study analyzes the research hotspots and frontiers of this field based on metrics including main research forces, core journals and papers, research hotspots and topics by using the methods of bibliometrics and text mining. The results revealed the following: (1) the number of papers is increasing rapidly in recent years. From 2015 to 2019, 929 papers were published, with an average of 185 papers per year. But the average cited times of those papers is declining, dropped from 6.01 in 2016 to 4.2 in 2019. The USA, UK, and China rank the top three of the number of papers. Univ Maryland, Univ Oxford and Univ Wisconsin have the greatest influence, with an average of more than 77 citations per paper; (2) The most cited journals are PNAS, WETLANDS, ECOLOGY, AND SOCIETY, which are cited 191.54, 53.91, and 40.00 respectively. Most papers were published in OA journals including SUSTAINABILITY, WATER, Forests since 2017. Ten core papers undertaking knowledge transfer in this field have been identified; (3) analysis of the keywords found a new trend of integration of natural science and humanities. In two development stages of 2000-2014 and 2015-2019, the research hotspots mainly focused on mountain water resources, forest resources, land resources and the impact of climate change and human activities, and there are obvious differences and characteristics in different stages. The hotspot worthy of attention in the near future is the assessment of mountain ecosystem services capacity and value. This is the first comprehensive visualization and analysis of the research hotspots and trends of mountain ecosystem services.
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Affiliation(s)
- Wenhao Liu
- Cryosphere Research Station on the Qinghai-Tibet Plateau, State Key Laboratory of Cryospheric Sciences, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou, 730000, China.
- University of Chinese Academy of Sciences, Beijing, 100049, China.
| | - Zengru Wang
- Cryosphere Research Station on the Qinghai-Tibet Plateau, State Key Laboratory of Cryospheric Sciences, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou, 730000, China
| | - Ren Li
- Cryosphere Research Station on the Qinghai-Tibet Plateau, State Key Laboratory of Cryospheric Sciences, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou, 730000, China.
- University of Chinese Academy of Sciences, Beijing, 100049, China.
| | - Tonghua Wu
- Cryosphere Research Station on the Qinghai-Tibet Plateau, State Key Laboratory of Cryospheric Sciences, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou, 730000, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
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Watanabe A, Katoh M, McMaster M, Anderson HA. Characterisation of Dissolved Organic Matter Fractions Released from Scottish Peatlands. ANAL SCI 2021; 37:1719-1725. [PMID: 34148921 DOI: 10.2116/analsci.20p450] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
A high concentration of dissolved organic matter is intimately related to the chemistry and ecology of water environments linked to peatlands. To understand the variations in the chemical characteristics of peat derived dissolved organic matter, those in drainage water from natural vegetation and an area containing Sitka spruce (Picea sitchensis), surface water (dubh lochans), and stream water associated with a peatland in central Scotland were analyzed after fractionation into two fulvic acids that were desorbed from an XAD-8 column with water (FAs(H2O)) and 0.1 M NaOH (FAs(NaOH)), humic acids, and dissolved non-humic substances. The elemental composition and the carbon composition as estimated by 13C cross polarisation/magic angle spinning nuclear magnetic resonance did not differ significantly between the FAs(H2O) and FAs(NaOH), whilst the FAs(H2O) were differentiated from the FAs(NaOH) by the greater proportion of carboxy groups with a low pKa at approximately 2. The carboxy group content and the distribution of carboxy groups with respect to the pKa of dissolved non-humic substances were similar to those of FAs(H2O), suggesting their importance as a metal carrier in water systems associated with peatland.
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Affiliation(s)
- Akira Watanabe
- Graduate School of Bioagricultural Sciences, Nagoya University
| | - Mariko Katoh
- Graduate School of Bioagricultural Sciences, Nagoya University
| | - Moira McMaster
- The Macaulay Institute (Present: the James Hutton Institute)
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6
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Sawicka K, Clark JM, Vanguelova E, Monteith DT, Wade AJ. Spatial properties affecting the sensitivity of soil water dissolved organic carbon long-term median concentrations and trends. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 780:146670. [PMID: 34030324 DOI: 10.1016/j.scitotenv.2021.146670] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Revised: 03/17/2021] [Accepted: 03/17/2021] [Indexed: 06/12/2023]
Abstract
It is increasingly clear that increases in dissolved organic carbon in upland waters in recent decades have often been dominated by acid deposition, but reasons for substantial variation in rates of change remain unclear. This paper focuses on the extent to which spatial properties, such as variation in soil properties, atmospheric deposition and climate, affect the sensitivity of DOC concentrations in soil water. The purpose is to i) examine evidence for differences in site average concentrations and trends in soil water DOC between sites with contrasting ecosystem properties, i.e. vegetation cover and soil type, and ii) identify the wider combination of site characteristics that best explain variation in these DOC metrics between sites. We collated soil water and deposition chemistry, soil chemistry and meteorological data from 15 long-term UK monitoring sites (1992-2010) covering a range of soils, vegetation, climate and acid deposition levels. Mineral soils under forests showed the greatest range of long-term mean DOC concentrations and trends. Regression analysis indicated that acid and sea-salt deposition, and soil sensitivity to acidification were the factors most strongly associated with spatial variation in mean DOC concentrations. Spatial variation in DOC trends were best explained by Al saturation and water flux. Overall, the sensitivity of DOC release from soil to changes in pollutant deposition could be related to the type of vegetation cover and soils chemistry properties, such as Al saturation, divalent base cation content and hydrological regime. The identification of the ecosystem properties that appear most influential in modifying DOC production and responses to long-term drivers, helps elucidate potential mechanistic explanations for differences in DOC dynamics across seemingly similar ecosystems, and points to the importance of DOC mobility in regulating its dynamics.
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Affiliation(s)
- Katarzyna Sawicka
- Soil Research Centre, Department of Geography and Environmental Science, University of Reading, Reading RG6 6DW, UK; UK Centre for Ecology & Hydrology, Environment Centre Wales, Deiniol Road, Bangor LL57 2UW, UK; Environmental Science Group, Wageningen University, PO Box 47, 6700 AA Wageningen, the Netherlands.
| | - Joanna M Clark
- Soil Research Centre, Department of Geography and Environmental Science, University of Reading, Reading RG6 6DW, UK
| | - Elena Vanguelova
- Centre for Ecosystems, Society and Biosecurity, Forest Research, Alice Holt Lodge, Farnham, Surrey GU10 4LH, UK
| | - Don T Monteith
- Environmental Change Network, UK Centre for Ecology and Hydrology, Lancaster Environment Centre, Bailrigg, Lancaster LA1 4AP, UK
| | - Andrew J Wade
- Soil Research Centre, Department of Geography and Environmental Science, University of Reading, Reading RG6 6DW, UK
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7
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Lawrence GB, Roy KM. Ongoing increases in dissolved organic carbon are sustained by decreases in ionic strength rather than decreased acidity in waters recovering from acidic deposition. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 766:142529. [PMID: 33158515 DOI: 10.1016/j.scitotenv.2020.142529] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Revised: 09/17/2020] [Accepted: 09/22/2020] [Indexed: 05/27/2023]
Abstract
Dissolved organic carbon (DOC) has received considerable attention in freshwater research, particularly since the early 2000s when increasing trends became apparent. However, remaining questions need to be resolved to address future effects of DOC on surface waters. This study was undertaken to determine (1) the relative importance of acidity and ionic strength in driving DOC increases in waters recovering from acidification and (2) the role played by long-term acid rain effects on soil. Data obtained from temporal and spatial monitoring of 142 headwater streams throughout the Adirondack region of New York (USA) were used to evaluate chemical relationships involving DOC. Year-round monitoring of three streams of differing acidification status were combined with intermittent stream surveys during spring snowmelt throughout this 24,243 km2 region that is recovering from acidification of soils and surface waters. Despite acidic deposition decreases reaching levels estimated for the early 1900s, DOC concentrations exhibited linear increases from the early 2000s through 2019. Ionic strength or conductivity showed consistent inverse relationships with DOC in all data comparisons from 2004-05 to 2018-19. In contrast, relationships between pH and DOC did not support increasing pH as an important factor in DOC increases. Inconsistent relationships between pH and DOC were due to strongly acidic organic acids that remain unprotonated throughout the pH range of these waters and limited weak-acid deprotonation below pH 6.2. Decreasing ionic strength increases DOC solubility by expanding the diffuse double layer, which fosters disaggregation of organic matter and dispersion of colloids. This affect controlled DOC solubilization below a pH of approximately 6.2. Distinguishing between ionic strength and pH effects is important because further large reductions in acidic deposition are not expected but continued soil-water dilution is likely from soil-Ca2+ depletion and the decreasing rate of Ca2+ leaching by SO42- and NO3-, which are still being released from soil organic matter.
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Affiliation(s)
- Gregory B Lawrence
- U.S. Geological Survey, New York Water Science Center, Troy, NY 12180, United States of America.
| | - Karen M Roy
- New York State Department of Environmental Conservation, Box 296, Ray Brook, NY 12977, United States of America.
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8
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Clutterbuck B, Burton W, Smith C, Yarnell RW. Vehicular tracks and the influence of land use and habitat protection in the British uplands. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 737:140243. [PMID: 32783847 DOI: 10.1016/j.scitotenv.2020.140243] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2020] [Revised: 06/10/2020] [Accepted: 06/13/2020] [Indexed: 06/11/2023]
Abstract
Uplands cover around 25% of the Earth's land surface and comprise highly sensitive soils and habitats of global ecological importance that together provision a suite of valuable ecosystem services. Access to upland areas for land management and recreation is increasingly dependent on the use of motorised vehicles. However, despite the widely acknowledged detrimental consequences of vehicle track development and use, this activity is not currently quantified or monitored. In this study, surfaced and unsurfaced vehicular tracks, footpaths and land cover in an approximately 5% sample of mainland British uplands (1910 km2) were mapped using aerial imagery dating between 2007 and 2016. An information theory approach was used to identify models that best predicted the presence and extent of surfaced tracks as a function of land cover, protected status, extent of blanket peat, proximity to human population and altitude. A total of 2104 km of track were recorded, with 27% defined as being surfaced. This equates to a mean (±SE) track density of 1.10 ± 0.15 km km-2 in current use by vehicles across upland Britain. Areas of managed heather and grass-dominated habitat were the primary predictors of the presence and extent of surfaced tracks and we found no evidence that areas of conservation interest with protective designation were less susceptible to track construction. These data indicate that wide-ranging vehicular track networks exist in ecologically sensitive environments across the British uplands, with implications for the integrity of sensitive habitats and soils. Land use and management activities that are not facilitating ecological improvement or conservation appear to be driving the presence of surfaced tracks in 'protected' areas. The findings suggest that: a) urgent review and revision of upland track legislation is required in Great Britain; and b) wider assessment of upland tracks should be undertaken to inform global conservation strategies for these environments.
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Affiliation(s)
- Ben Clutterbuck
- School of Animal, Rural and Environmental Sciences, Nottingham Trent University, Brackenhurst Campus, Southwell, Nottinghamshire NG25 0QF, UK.
| | - Wilmie Burton
- School of Animal, Rural and Environmental Sciences, Nottingham Trent University, Brackenhurst Campus, Southwell, Nottinghamshire NG25 0QF, UK
| | - Carl Smith
- School of Animal, Rural and Environmental Sciences, Nottingham Trent University, Brackenhurst Campus, Southwell, Nottinghamshire NG25 0QF, UK; Department of Ecology and Vertebrate Zoology, University of Łódź, 12/16 Banacha Street, 90-237 Łódź, Poland; Institute of Vertebrate Biology, Academy of Sciences of the Czech Republic, Květná 8, 603 65 Brno, Czech Republic
| | - Richard W Yarnell
- School of Animal, Rural and Environmental Sciences, Nottingham Trent University, Brackenhurst Campus, Southwell, Nottinghamshire NG25 0QF, UK
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Abstract
Oil pollutants, due to their toxicity, mutagenicity, and carcinogenicity, are considered a serious threat to human health and the environment. Petroleum hydrocarbons compounds, for instance, benzene, toluene, ethylbenzene, xylene, are among the natural compounds of crude oil and petrol and are often found in surface and underground water as a result of industrial activities, especially the handling of petrochemicals, reservoir leakage or inappropriate waste disposal processes. Methods based on the conventional wastewater treatment processes are not able to effectively eliminate oil compounds, and the high concentrations of these pollutants, as well as active sludge, may affect the activities and normal efficiency of the refinery. The methods of removal should not involve the production of harmful secondary pollutants in addition to wastewater at the level allowed for discharge into the environment. The output of sewage filtration by coagulation and dissolved air flotation (DAF) flocculation can be transferred to a biological reactor for further purification. Advanced coagulation methods such as electrocoagulation and flocculation are more advanced than conventional physical and chemical methods, but the major disadvantages are the production of large quantities of dangerous sludge that is unrecoverable and often repelled. Physical separation methods can be used to isolate large quantities of petroleum compounds, and, in some cases, these compounds can be recycled with a number of processes. The great disadvantage of these methods is the high demand for energy and the high number of blockages and clogging of a number of tools and equipment used in this process. Third-party refinement can further meet the objective of water reuse using methods such as nano-filtration, reverse osmosis, and advanced oxidation. Adsorption is an emergency technology that can be applied using minerals and excellent materials using low-cost materials and adsorbents. By combining the adsorption process with one of the advanced methods, in addition to lower sludge production, the process cost can also be reduced.
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Škerlep M, Steiner E, Axelsson A, Kritzberg ES. Afforestation driving long-term surface water browning. GLOBAL CHANGE BIOLOGY 2020; 26:1390-1399. [PMID: 31667991 PMCID: PMC7079054 DOI: 10.1111/gcb.14891] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2019] [Accepted: 09/22/2019] [Indexed: 05/22/2023]
Abstract
Increase in surface water color (browning), caused by rising dissolved organic carbon (DOC) and iron concentrations, has been widely reported and studied in the last couple of decades. This phenomenon has implications to aquatic ecosystem function and biogeochemical carbon cycling. While recovery from acidification and changes in climate-related variables, such as precipitation and length of growing season, are recognized as drivers behind browning, land-use change has received less attention. In this study, we include all of the above factors and aim to discern their individual and combined contribution to water color variation in an unprecedentedly long (1940-2016) and highly resolved dataset (~20 times per month), from a river in southern Sweden. Water color showed high seasonal variability and a marked long-term increase, particularly in the latter half of the dataset (~1980). Short-term and seasonal variations were best explained by precipitation, with temperature playing a secondary role. All explanatory variables (precipitation, temperature, S deposition, and land-use change) contributed significantly and together predicted 75% of the long-term variation in water color. Long-term change was best explained by a pronounced increase in Norway spruce (Picea abies Karst) volume-a measure of land-use change and a proxy for buildup of organic soil layers-and by change in atmospheric S deposition. When modeling water color with a combination of explanatory variables, Norway spruce showed the highest contribution to explaining long-term variability. This study highlights the importance of considering land-use change as a factor behind browning and combining multiple factors when making predictions in water color and DOC.
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Affiliation(s)
| | | | - Anna‐Lena Axelsson
- Department of Forest Resource ManagementSwedish University of Agricultural SciencesUmeåSweden
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11
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Watson A, Wilson JD. Seven decades of mountain hare counts show severe declines where high‐yield recreational game bird hunting is practised. J Appl Ecol 2018. [DOI: 10.1111/1365-2664.13235] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Adam Watson
- Centre for Ecology and Hydrology Penicuik UK
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12
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Harper AR, Doerr SH, Santin C, Froyd CA, Sinnadurai P. Prescribed fire and its impacts on ecosystem services in the UK. THE SCIENCE OF THE TOTAL ENVIRONMENT 2018; 624:691-703. [PMID: 29272838 DOI: 10.1016/j.scitotenv.2017.12.161] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2017] [Revised: 12/13/2017] [Accepted: 12/14/2017] [Indexed: 05/21/2023]
Abstract
The impacts of vegetation fires on ecosystems are complex and varied affecting a range of important ecosystem services. Fire has the potential to affect the physicochemical and ecological status of water systems, alter several aspects of the carbon cycle (e.g. above- and below-ground carbon storage) and trigger changes in vegetation type and structure. Globally, fire is an essential part of land management in fire-prone regions in, e.g. Australia, the USA and some Mediterranean countries to mitigate the likelihood of catastrophic wildfires and sustain healthy ecosystems. In the less-fire prone UK, fire has a long history of usage in management for enhancing the productivity of heather, red grouse and sheep. This distinctly different socioeconomic tradition of burning underlies some of the controversy in recent decades in the UK around the use of fire. Negative public opinion and opposition from popular media have highlighted concerns around the detrimental impacts burning can have on the health and diversity of upland habitats. It is evident there are many gaps in the current knowledge around the environmental impacts of prescribed burning in less fire-prone regions (e.g. UK). Land owners and managers require a greater level of certainty on the advantages and disadvantages of prescribed burning in comparison to other techniques to better inform management practices. This paper addresses this gap by providing a critical review of published work and future research directions related to the impacts of prescribed fire on three key aspects of ecosystem services: (i) water quality, (ii) carbon dynamics and (iii) habitat composition and structure (biodiversity). Its overall aims are to provide guidance based on the current state-of-the-art for researchers, land owners, managers and policy makers on the potential effects of the use of burning and to inform the wider debate about the place of fire in modern conservation and land management in humid temperate ecosystems.
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Affiliation(s)
- Ashleigh R Harper
- Department of Geography, Swansea University, Singleton Park, Swansea SA2 8PP, UK.
| | - Stefan H Doerr
- Department of Geography, Swansea University, Singleton Park, Swansea SA2 8PP, UK
| | - Cristina Santin
- Department of Geography, Swansea University, Singleton Park, Swansea SA2 8PP, UK; Department of Biosciences, Swansea University, Singleton Park, Swansea SA2 8PP, UK
| | - Cynthia A Froyd
- Department of Biosciences, Swansea University, Singleton Park, Swansea SA2 8PP, UK
| | - Paul Sinnadurai
- Brecon Beacons National Park Authority, Cambrian Way, Brecon LD3 7HP, UK
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Davies GM, Kettridge N, Stoof CR, Gray A, Ascoli D, Fernandes PM, Marrs R, Allen KA, Doerr SH, Clay GD, McMorrow J, Vandvik V. The role of fire in UK peatland and moorland management: the need for informed, unbiased debate. Philos Trans R Soc Lond B Biol Sci 2017; 371:rstb.2015.0342. [PMID: 27216512 PMCID: PMC4874417 DOI: 10.1098/rstb.2015.0342] [Citation(s) in RCA: 62] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/29/2016] [Indexed: 11/16/2022] Open
Abstract
Fire has been used for centuries to generate and manage some of the UK's cultural landscapes. Despite its complex role in the ecology of UK peatlands and moorlands, there has been a trend of simplifying the narrative around burning to present it as an only ecologically damaging practice. That fire modifies peatland characteristics at a range of scales is clearly understood. Whether these changes are perceived as positive or negative depends upon how trade-offs are made between ecosystem services and the spatial and temporal scales of concern. Here we explore the complex interactions and trade-offs in peatland fire management, evaluating the benefits and costs of managed fire as they are currently understood. We highlight the need for (i) distinguishing between the impacts of fires occurring with differing severity and frequency, and (ii) improved characterization of ecosystem health that incorporates the response and recovery of peatlands to fire. We also explore how recent research has been contextualized within both scientific publications and the wider media and how this can influence non-specialist perceptions. We emphasize the need for an informed, unbiased debate on fire as an ecological management tool that is separated from other aspects of moorland management and from political and economic opinions. This article is part of the themed issue ‘The interaction of fire and mankind’.
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Affiliation(s)
- G Matt Davies
- School of Environment and Natural Resources, The Ohio State University, Kottman Hall, 2021 Coffey Road, Columbus, OH 43210, USA
| | - Nicholas Kettridge
- School of Geography, Earth and Environmental Sciences, University of Birmingham, Birmingham B31 2DX, UK
| | - Cathelijne R Stoof
- Soil Geography and Landscape Group, Wageningen University, PO Box 47, Wageningen 6700 AA, The Netherlands
| | - Alan Gray
- NERC Centre for Ecology and Hydrology, Bush Estate, Penicuik, Edinburgh EH26 0QB, UK
| | - Davide Ascoli
- Department of Agricultural, Forest and Food Sciences, University of Torino, Largo Paolo Braccini 2, Grugliasco (TO) 10095, Italy
| | - Paulo M Fernandes
- Centro de Investigação e de Tecnologias Agro-Ambientais e Biológicas, Universidade de Tras-os-Montes e Alto Douro, Vila Real, Portugal
| | - Rob Marrs
- School of Environmental Sciences, University of Liverpool, Liverpool L69 3GP, UK
| | - Katherine A Allen
- School of Environmental Sciences, University of Liverpool, Liverpool L69 3GP, UK
| | - Stefan H Doerr
- Department of Geography, Swansea University, Swansea, UK
| | - Gareth D Clay
- School of Environment, Education and Development, The University of Manchester, Manchester M13 9PL, UK
| | - Julia McMorrow
- School of Environment, Education and Development, The University of Manchester, Manchester M13 9PL, UK
| | - Vigdis Vandvik
- Department of Biology, University of Bergen, Postboks 7803, Bergen 5020, Norway
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Evans CD, Malcolm IA, Shilland EM, Rose NL, Turner SD, Crilly A, Norris D, Granath G, Monteith DT. Sustained Biogeochemical Impacts of Wildfire in a Mountain Lake Catchment. Ecosystems 2016. [DOI: 10.1007/s10021-016-0064-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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15
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Grand-Clement E, Luscombe DJ, Anderson K, Gatis N, Benaud P, Brazier RE. Antecedent conditions control carbon loss and downstream water quality from shallow, damaged peatlands. THE SCIENCE OF THE TOTAL ENVIRONMENT 2014; 493:961-973. [PMID: 25010944 DOI: 10.1016/j.scitotenv.2014.06.091] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2014] [Revised: 06/19/2014] [Accepted: 06/20/2014] [Indexed: 06/03/2023]
Abstract
Losses of dissolved organic carbon (DOC) from drained peatlands are of concern, due to the effects this has on the delivery of ecosystem services, and especially on the long-term store of carbon and the provision of drinking water. Most studies have looked at the effect of drainage in deep peat; comparatively, little is known about the behaviour of shallow, climatically marginal peatlands. This study examines water quality (DOC, Abs(400), pH, E4/E6 and C/C) during rainfall events from such environments in the south west UK, in order to both quantify DOC losses, and understand their potential for restoration. Water samples were taken over a 19 month period from a range of drains within two different experimental catchments in Exmoor National Park; data were analysed on an event basis. DOC concentrations ranging between 4 and 21 mg L(-1) are substantially lower than measurements in deep peat, but remain problematic for the water treatment process. Dryness plays a critical role in controlling DOC concentrations and water quality, as observed through spatial and seasonal differences. Long-term changes in depth to water table (30 days before the event) are likely to impact on DOC production, whereas discharge becomes the main control over DOC transport at the time scale of the rainfall/runoff event. The role of temperature during events is attributed to an increase in the diffusion of DOC, and therefore its transport. Humification ratios (E4/E6) consistently below 5 indicate a predominance of complex humic acids, but increased decomposition during warmer summer months leads to a comparatively higher losses of fulvic acids. This work represents a significant contribution to the scientific understanding of the behaviour and functioning of shallow damaged peatlands in climatically marginal locations. The findings also provide a sound baseline knowledge to support research into the effects of landscape restoration in the future.
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Affiliation(s)
- E Grand-Clement
- Geography, College of Life and Environmental Sciences, Amory Building, Rennes Drive, Exeter, Devon EX4 4RJ, United Kingdom.
| | - D J Luscombe
- Geography, College of Life and Environmental Sciences, Amory Building, Rennes Drive, Exeter, Devon EX4 4RJ, United Kingdom.
| | - K Anderson
- Environment and Sustainability Institute, University of Exeter, Penryn, Cornwall TR10 9FE, United Kingdom.
| | - N Gatis
- Geography, College of Life and Environmental Sciences, Amory Building, Rennes Drive, Exeter, Devon EX4 4RJ, United Kingdom.
| | - P Benaud
- Geography, College of Life and Environmental Sciences, Amory Building, Rennes Drive, Exeter, Devon EX4 4RJ, United Kingdom.
| | - R E Brazier
- Geography, College of Life and Environmental Sciences, Amory Building, Rennes Drive, Exeter, Devon EX4 4RJ, United Kingdom.
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16
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Long-term Trends of Organic Carbon Concentrations in Freshwaters: Strengths and Weaknesses of Existing Evidence. WATER 2014. [DOI: 10.3390/w6051360] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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17
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Jones DL, Simfukwe P, Hill PW, Mills RTE, Emmett BA. Evaluation of dissolved organic carbon as a soil quality indicator in national monitoring schemes. PLoS One 2014; 9:e90882. [PMID: 24633085 PMCID: PMC3954595 DOI: 10.1371/journal.pone.0090882] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2013] [Accepted: 02/03/2014] [Indexed: 11/19/2022] Open
Abstract
Background Monitoring the properties of dissolved organic carbon (DOC) in soil water is frequently used to evaluate changes in soil quality and to explain shifts in freshwater ecosystem functioning. Methods Using >700 individual soils (0–15 cm) collected from a 209,331 km2 area we evaluated the relationship between soil classification (7 major soil types) or vegetation cover (8 dominant classes, e.g. cropland, grassland, forest) and the absorbance properties (254 and 400 nm), DOC quantity and quality (SUVA, total soluble phenolics) of soil water. Results Overall, a good correlation (r2 = 0.58) was apparent between soil water absorbance and DOC concentration across the diverse range of soil types tested. In contrast, both DOC and the absorbance properties of soil water provided a poor predictor of SUVA or soluble phenolics which we used as a measure of humic substance concentration. Significant overlap in the measured ranges for UV absorbance, DOC, phenolic content and especially SUVA of soil water were apparent between the 8 vegetation and 7 soil classes. A number of significant differences, however, were apparent within these populations with total soluble phenolics giving the greatest statistical separation between both soil and vegetation groups. Conclusions We conclude that the quality of DOC rather than its quantity provides a more useful measure of soil quality in large scale surveys.
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Affiliation(s)
- David L. Jones
- School of the Environment, Natural Resources & Geography, Bangor University, Bangor, Gwynedd, United Kingdom
- * E-mail:
| | - Paul Simfukwe
- School of the Environment, Natural Resources & Geography, Bangor University, Bangor, Gwynedd, United Kingdom
| | - Paul W. Hill
- School of the Environment, Natural Resources & Geography, Bangor University, Bangor, Gwynedd, United Kingdom
| | - Robert T. E. Mills
- Ecole Polytechnique Fédérale de Lausanne (EPFL), School of Architecture, Civil and Environmental Engineering (ENAC), Laboratory of Ecological Systems (ECOS), Lausanne, Switzerland
| | - Bridget A. Emmett
- Centre for Ecology and Hydrology, Environment Centre Wales, Bangor, Gwynedd, United Kingdom
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Ritson JP, Graham NJD, Templeton MR, Clark JM, Gough R, Freeman C. The impact of climate change on the treatability of dissolved organic matter (DOM) in upland water supplies: a UK perspective. THE SCIENCE OF THE TOTAL ENVIRONMENT 2014; 473-474:714-30. [PMID: 24412917 DOI: 10.1016/j.scitotenv.2013.12.095] [Citation(s) in RCA: 86] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/28/2013] [Revised: 12/19/2013] [Accepted: 12/19/2013] [Indexed: 05/06/2023]
Abstract
Climate change in the UK is expected to cause increases in temperatures, altered precipitation patterns and more frequent and extreme weather events. In this review we discuss climate effects on dissolved organic matter (DOM), how altered DOM and water physico-chemical properties will affect treatment processes and assess the utility of techniques used to remove DOM and monitor water quality. A critical analysis of the literature has been undertaken with a focus on catchment drivers of DOM character, removal of DOM via coagulation and the formation of disinfectant by-products (DBPs). We suggest that: (1) upland catchments recovering from acidification will continue to produce more DOM with a greater hydrophobic fraction as solubility controls decrease; (2) greater seasonality in DOM export is likely in future due to altered precipitation patterns; (3) changes in species diversity and water properties could encourage algal blooms; and (4) that land management and vegetative changes may have significant effects on DOM export and treatability but require further research. Increases in DBPs may occur where catchments have high influence from peatlands or where algal blooms become an issue. To increase resilience to variable DOM quantity and character we suggest that one or more of the following steps are undertaken at the treatment works: a) 'enhanced coagulation' optimised for DOM removal; b) switching from aluminium to ferric coagulants and/or incorporating coagulant aids; c) use of magnetic ion-exchange (MIEX) pre-coagulation; and d) activated carbon filtration post-coagulation. Fluorescence and UV absorbance techniques are highlighted as potential methods for low-cost, rapid on-line process optimisation to improve DOM removal and minimise DBPs.
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Affiliation(s)
- J P Ritson
- Grantham Institute for Climate Change, Imperial College London, South Kensington, London SW7 2AZ, UK; Department of Civil and Environmental Engineering, Imperial College London, South Kensington, London, SW7 2AZ, UK.
| | - N J D Graham
- Department of Civil and Environmental Engineering, Imperial College London, South Kensington, London, SW7 2AZ, UK
| | - M R Templeton
- Department of Civil and Environmental Engineering, Imperial College London, South Kensington, London, SW7 2AZ, UK
| | - J M Clark
- Walker Institute for Climate Systems Research and Soil Research Centre, Geography and Environmental Science, School of Human and Environmental Sciences, University of Reading, Whiteknights, Reading, RG6 6DW, UK
| | - R Gough
- Wolfson Carbon Capture Laboratory, School of Biological Sciences, Bangor University, Bangor, Gwynedd, LL57 2UW, UK
| | - C Freeman
- Wolfson Carbon Capture Laboratory, School of Biological Sciences, Bangor University, Bangor, Gwynedd, LL57 2UW, UK
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19
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Rowe EC, Tipping E, Posch M, Oulehle F, Cooper DM, Jones TG, Burden A, Hall J, Evans CD. Predicting nitrogen and acidity effects on long-term dynamics of dissolved organic matter. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2014; 184:271-282. [PMID: 24077255 DOI: 10.1016/j.envpol.2013.08.023] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2013] [Revised: 08/08/2013] [Accepted: 08/11/2013] [Indexed: 06/02/2023]
Abstract
Increases in dissolved organic carbon (DOC) fluxes may relate to changes in sulphur and nitrogen pollution. We integrated existing models of vegetation growth and soil organic matter turnover, acid-base dynamics, and organic matter mobility, to form the 'MADOC' model. After calibrating parameters governing interactions between pH and DOC dissolution using control treatments on two field experiments, MADOC reproduced responses of pH and DOC to additions of acidifying and alkalising solutions. Long-term trends in a range of acid waters were also reproduced. The model suggests that the sustained nature of observed DOC increases can best be explained by a continuously replenishing potentially-dissolved carbon pool, rather than dissolution of a large accumulated store. The simulations informed the development of hypotheses that: DOC increase is related to plant productivity increase as well as to pH change; DOC increases due to nitrogen pollution will become evident, and be sustained, after soil pH has stabilised.
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Affiliation(s)
- E C Rowe
- Centre for Ecology and Hydrology, ECW, Deiniol Road, Bangor LL57 2UW, UK.
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20
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Grand-Clement E, Anderson K, Smith D, Luscombe D, Gatis N, Ross M, Brazier RE. Evaluating ecosystem goods and services after restoration of marginal upland peatlands in South-West England. J Appl Ecol 2013. [DOI: 10.1111/1365-2664.12039] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Emilie Grand-Clement
- Geography; College of Life and Environmental Sciences; University of Exeter; Rennes Drive, Streatham Campus Exeter EX4 4RJ UK
- South West Water; Rydon Lane Exeter EX2 7HR UK
| | - Karen Anderson
- Environment and Sustainability Institute; University of Exeter; Cornwall Campus Penryn TR10 9EZ UK
| | - David Smith
- South West Water; Rydon Lane Exeter EX2 7HR UK
| | - David Luscombe
- Geography; College of Life and Environmental Sciences; University of Exeter; Rennes Drive, Streatham Campus Exeter EX4 4RJ UK
| | - Naomi Gatis
- Geography; College of Life and Environmental Sciences; University of Exeter; Rennes Drive, Streatham Campus Exeter EX4 4RJ UK
| | - Martin Ross
- South West Water; Rydon Lane Exeter EX2 7HR UK
| | - Richard E. Brazier
- Geography; College of Life and Environmental Sciences; University of Exeter; Rennes Drive, Streatham Campus Exeter EX4 4RJ UK
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22
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Räike A, Kortelainen P, Mattsson T, Thomas DN. 36 year trends in dissolved organic carbon export from Finnish rivers to the Baltic Sea. THE SCIENCE OF THE TOTAL ENVIRONMENT 2012; 435-436:188-201. [PMID: 22854090 DOI: 10.1016/j.scitotenv.2012.06.111] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/05/2012] [Revised: 06/21/2012] [Accepted: 06/30/2012] [Indexed: 05/15/2023]
Abstract
Increasing dissolved organic carbon (DOC) concentrations in lakes, rivers and streams in northern mid latitudes have been widely reported during the last two decades, but relatively few studies have dealt with trends in DOC export. We studied the export of DOC from Finnish rivers to the Baltic Sea between 1975 and 2010, and estimated trends in DOC fluxes (both flow normalised and non-normalised). The study encompassed the whole Finnish Baltic Sea catchment area (301,000 km(2)) covering major land use patterns in the boreal zone. Finnish rivers exported annually over 900,000 t DOC to the Baltic Sea, and the mean area specific export was 3.5 t km(-2). The highest export (7.3t km(-2)) was measured in peat dominated catchments, whereas catchments rich in lakes had the lowest export (2.2 t km(-2)). Inter-annual variation in DOC export was high and controlled mainly by hydrology. There was no overall trend in the annual water flow, although winter flow increased in northern Finland over 36 years. Despite the numerous studies showing increases in DOC concentrations in streams and rivers in the northern hemisphere, we could not find any evidence of increases in DOC export to the northern Baltic Sea from Finnish catchments since 1975.
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Affiliation(s)
- Antti Räike
- Finnish Environment Institute (SYKE), P.O. Box 140, FI-00251, Helsinki, Finland.
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Holden J, Chapman PJ, Palmer SM, Kay P, Grayson R. The impacts of prescribed moorland burning on water colour and dissolved organic carbon: a critical synthesis. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2012; 101:92-103. [PMID: 22406849 DOI: 10.1016/j.jenvman.2012.02.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2011] [Revised: 12/23/2011] [Accepted: 02/04/2012] [Indexed: 05/31/2023]
Abstract
Discolouration of natural surface waters due to the humic component of dissolved organic carbon (DOC) is a costly problem for water supply companies. This paper reviews what is known about the impacts of prescribed moorland vegetation burning on water colour. Relevant research has taken place at three scales: laboratory experiments on peat cores, plot scale sampling of soil waters and catchment scale sampling of stream waters. While laboratory studies suggest burning increases colour production, the evidence from catchment and plot studies is contradictory. Plot studies suggest colour production may decrease or remain unchanged following burning although there is evidence for some transient changes. Catchment studies suggest prescribed moorland burning causes stream water colour to increase, although in most cases the evidence is not clear cut since most studies could not clearly disentangle the effects of burning from those of vegetation cover. The differences in findings between plot and catchment studies may be explained by: i) the short-term nature of some studies which do not measure long-term response and recovery times to burning; ii) the lack of colour measurements from shallow soil depths which contribute more to streamflow than soil water from deeper in the peat; and iii) the possibility of hydrological interactions occurring between different experimental plots at some sites. Additionally, the increase in recent patch burning in some catchments that has been statistically attributed by some authors to increases in stream water colour cannot be reconciled with theoretical calculations. When dilution with waters derived from other parts of the catchment are taken into account, large values of colour have to be theoretically derived from those recently burnt areas that occupy a small proportion of the catchment area in order to balance the change in stream water colour observed in recent years. Therefore, much further process-based work is required to properly investigate whether prescribed vegetation burning is a direct driver of enhanced colour and DOC in upland streams, rivers and lakes.
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Affiliation(s)
- J Holden
- School of Geography, University of Leeds, Leeds, UK.
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Kerr JG, Eimers MC. Decreasing soil water Ca2+ reduces DOC adsorption in mineral soils: implications for long-term DOC trends in an upland forested catchment in southern Ontario, Canada. THE SCIENCE OF THE TOTAL ENVIRONMENT 2012; 427-428:298-307. [PMID: 22554533 DOI: 10.1016/j.scitotenv.2012.04.016] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/12/2011] [Revised: 04/04/2012] [Accepted: 04/05/2012] [Indexed: 05/31/2023]
Abstract
Positive trends in dissolved organic carbon (DOC) concentration have been observed in surface waters throughout North America and northern Europe. Although adsorption in mineral soils is an important driver of DOC in upland streams, little is known about the potential for changes in DOC adsorption to contribute to these trends. We hypothesized that long-term declines in soil water Ca(2+) levels, in response to declining acid deposition, might influence DOC adsorption and that this could contribute to long-term DOC trends in an upland forested catchment in south-central Ontario, Canada. Between 1987 and 2009, DOC concentrations increased significantly (p<0.05) in stream water and B horizon soil water (2 out of 3 sites). The null point DOC concentration (DOC(np)), which is a measure of the soil water DOC concentration at equilibrium with the soil, ranged from 1.27 to 3.75 mg L(-1) in B horizon soils. This was similar to the mean DOC concentrations of B horizon soil water (2.04-6.30 mg L(-1)) and stream water (2.20 mg L(-1)), indicating that soil and stream water DOC concentrations are controlled by equilibrium processes at the soil-water interface. Adsorption experiments using variable Ca(2+) concentrations demonstrated that as Ca(2+) decreased the DOC(np) increased (1.96 to 4.74 mg L(-1)), which was consistent with the observed negative correlation between DOC and Ca(2+) in B horizon soil water (p<0.05; r(2)=0.21). Additional adsorption experiments showed that Na(+) had no effect on DOC adsorption (p>0.05), indicating that changes in DOC adsorption might be related to cation bridging. We conclude that declines in soil water Ca(2+) concentration can contribute to increasing DOC trends in upland streams by reducing DOC adsorption in mineral soils.
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Affiliation(s)
- Jason Grainger Kerr
- Department of Geography, Trent University, Peterborough, ON, Canada K9J 7B8.
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