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| 2. |
- Carlsson, Magnus, et al.
(författare)
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Charcoal Application to Arable Soil: Effects on CO2 Emissions
- 2012
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Ingår i: Communications in Soil Science and Plant Analysis. - : Informa UK Limited. - 0010-3624 .- 1532-2416. ; 43, s. 2262-2273
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Tidskriftsartikel (refereegranskat)abstract
- Activated carbon and commercial household charcoal were added to soil in a 36-day incubation study at 20 degrees C measuring carbon dioxide evolution. The black carbon materials were found to decompose slowly, releasing between 1.4% and 0.8% of their carbon content per year, respectively. The main experiment tested whether the black carbon additions to soil (2% and 4% by mass) affected decomposition of selected substrates in soil, both respiration dynamics and total respiration. The results indicated that the black carbon materials tested had no effect on total respiration from added glucose. However, decomposition rates of amylose, xylan, casein, and ryegrass were reduced in soil with addition of activated carbon but were not significantly affected by household charcoal. A larger surface area of activated carbon than that of household charcoal, and thus a greater adsorption capacity for organic compounds and exo-enzymes required to break down water-insoluble substrates, may explain the results.
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| 4. |
- Ghafoor, Abdul, et al.
(författare)
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Measurements and modeling of pesticide persistence in soil at the catchment scale
- 2011
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Ingår i: Science of the Total Environment. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; 409, s. 1900-1908
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Tidskriftsartikel (refereegranskat)abstract
- Degradation of pesticides in soils is both spatially variable and also one of the most sensitive factors determining losses to surface water and groundwater. To date, no general guidance is available on suitable approaches for dealing with spatial variation in pesticide degradation in catchment or regional scale modeling applications. The purpose of the study was therefore to study the influence of various soil physical, chemical and microbiological characteristics on pesticide persistence in the contrasting cultivated soils found in a small (13 km(2)) agricultural catchment in Sweden and to develop and test a simple model approach that could support catchment scale modeling. Persistence of bentazone, glyphosate and isoproturon was investigated in laboratory incubation experiments. Degradation rate constants were highly variable with coefficients of variation ranging between 42 and 64% for the three herbicides. Multiple linear regression analysis and Mallows Cp statistic were employed to select the best set of independent parameters accounting for the variation in degradation. Soil pH and the proportion of active microorganisms (r) together explained 69% of the variation in the bentazone degradation rate constant; the Freundlich sorption co-efficient (K-f) and soil laccase activity together explained 88% of the variation in degradation rate of glyphosate, while soil pH was a significant predictor (p < 0.05) for isoproturon persistence. However, correlations between many potential predictor variables made clear interpretations of the statistical analysis difficult. Multiplicative models based on two predictors chosen 'a priori', one accounting for microbial activity (e.g. microbial respiration, laccase activity or the surrogate variable soil organic carbon, SOC) and one accounting for the effects of sorption on bioavailability, showed promise to support predictions of degradation for large-scale modeling applications, explaining up to 50% of the variation in herbicide persistence. (C) 2011 Elsevier B.V. All rights reserved.
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| 6. |
- Ghafoor, Abdul, et al.
(författare)
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Modeling Spatial Variation in Microbial Degradation of Pesticides in Soil
- 2011
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Ingår i: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 45, s. 6411-6419
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Tidskriftsartikel (refereegranskat)abstract
- Currently, no general guidance is available on suitable approaches for dealing with spatial variation in the first-order pesticide degradation rate constant k even though it is a very sensitive parameter and often highly variable at the field, catchment, and regional scales. Supported by some mechanistic reasoning, we propose a simple general modeling approach to predict k from the sorption constant, which reflects bioavailability, and easily measurable surrogate variables for microbial biomass/activity (organic carbon and clay contents). The soil depth was also explicitly included as an additional predictor variable. This approach was tested in a meta-analysis of available literature data using bootstrapped partial least-squares regression. It explained 73% of the variation in k for the 19 pesticide-study combinations (n = 212) in the database. When 4 of the 19 pesticide-study combinations were excluded (n = 169), the approach explained 80% of the variation in the degradation rate constant. We conclude that the approach shows promise as an effective way to account for the effects of bioavailability and microbial activity on microbial pesticide degradation in large-scale model applications.
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| 7. |
- Ghafoor, Abdul, et al.
(författare)
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Modelling pesticide sorption in the surface and subsurface soils of an agricultural catchment
- 2013
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Ingår i: Pest Management Science. - : Wiley. - 1526-498X .- 1526-4998. ; 69, s. 919-929
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Tidskriftsartikel (refereegranskat)abstract
- CONCLUSIONInformation on clay, iron and aluminium oxides and soil pH, in addition to organic carbon, is needed for accurate prediction of pesticide leaching. The variables f(oc), f(clay) and pH are generally available, whereas measurements of oxides of Al and Fe are rarely reported. The authors therefore emphasise the need to measure and report contents of oxides of Al and Fe in soil survey databases, because small variations in their concentrations may contribute significantly to large variations in sorption, especially of ionisable pesticides. (c) 2012 Society of Chemical Industry
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| 8. |
- Hallgren, Sunita, et al.
(författare)
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Karaktärisering avkemikalieläckage, desshalter och transportvägarfrån växthus och andrahårdgjorda ytor
- 2013
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Tidigare mätningar har visat att det finns risk att växtskyddsmedel som använts i växthus kan leta sig uttill vattendrag. För att ta reda på mer fakta kring hur läckage av växtskyddsmedel kan ske från växthusoch hårdgjorda ytor har nya mätningar gjorts inom ramen för detta delprojekt, på uppdrag avNaturvårdsverket.EFSA utreder beräkningsmodeller för spridningsvägar för växthus. En första slutsats som dragits närförsök gjorts att skapa gemensamma miljöriskbedömningar är att det saknas passande definitioner förväxthusområdet.Analys av 112 olika substanser har gjorts i 18 st jordprover från 6 st olika typer av trädgårdsföretag.Bland de 112 substanserna finns både tillåtna och sedan tidigare förbjudna ämnen. 36 olika ämnen harkunnat detekteras i jordproverna. De halter som hittats är låga och ligger nära detektionsgränsen föranalyserna. Halterna som hittats i proverna är starkt kopplat till den aktiva substansens kemiskaegenskaper samt nedbrytningshastigheten i jord och vatten och dess löslighet i vatten. Flera avsubstanserna är nedbrytningsprodukter av använda växtskyddsmedel. Prover har tagits på tre olika djupi marken - 0-10, 10-20 och 20-30 cm. I samtliga prover är halterna av kemikalierester högst i det överstajordskiktet 0-10 cm. Halterna varierar mycket mellan de olika företagen. Generellt är nivåerna högre iprydnadsväxtodlingar än i grönsaksföretag. Behovet och användningen av kemikalier är starkt kopplat tillde kulturer som odlas. Flera av de substanser som har använts har inte återfunnits i jordproverna.
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| 9. |
- Hallin, Sara, et al.
(författare)
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Soil Functional Operating Range Linked to Microbial Biodiversity and Community Composition Using Denitrifiers as Model Guild
- 2012
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Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 7
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Tidskriftsartikel (refereegranskat)abstract
- Soil microorganisms are key players in biogeochemical cycles. Yet, there is no consistent view on the significance of microbial biodiversity for soil ecosystem functioning. According to the insurance hypothesis, declines in ecosystem functioning due to reduced biodiversity are more likely to occur under fluctuating, extreme or rapidly changing environmental conditions. Here, we compare the functional operating range, a new concept defined as the complete range of environmental conditions under which soil microbial communities are able to maintain their functions, between four naturally assembled soil communities from a long-term fertilization experiment. A functional trait approach was adopted with denitrifiers involved in nitrogen cycling as our model soil community. Using short-term temperature and salt gradients, we show that the functional operating range was broader and process rates were higher when the soil community was phylogenetically more diverse. However, key bacterial genotypes played an important role for maintaining denitrification as an ecosystem functioning under certain conditions.
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