| 1. |
- Boström, Gustaf, et al.
(author)
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Riskkartering av bekämpningsmedel i Skånes grundvatten : simuleringar med MACRO-SE
- 2015
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Reports (other academic/artistic)abstract
- Syftet med detta projekt har varit att göra en kartering av riskerna med bekämpningsmedelsläckage till grundvatten i Skåne. Karteringen utfördes genom simuleringar med riskbedömningsverktyget MACRO-SE som har utvecklats inom Kompetenscentrum för kemiska bekämpningsmedel (CKB) vid Sveriges lantbruksuniversitet (SLU) i Uppsala. Bearbetning och analys av simuleringsresultaten har gjorts av CKB i samarbete med Länsstyrelsen Skåne. Riskkarteringen har utförts för bekämpningsmedlen bentazon, isoproturon, kvinmerak, MCPA, metazaklor och metribuzin vilka tidigare har påvisats i grundvatten. Dessa substanser är också representativa för en stor del av jordbruket i Skåne då de används i stor mängd och tillsammans täcker in en stor del av alla grödor som odlas i länet. Tidigare kunskapssammanställningar pekar på att det framförallt är äldre, idag förbjudna ämnen som hittas i djupare grundvatten. Men eftersom det finns en, ofta lång, tidsfördröjning mellan att ett ämne sprutas på markytan tills det att det kan infiltrera ner till grundvattnet är det intressant att närmare studera om även dagens användning av bekämpningsmedel framöver kan leda till förekomst av olika substanser i grundvattnet. Inför simuleringarna definierades scenarier som motsvarar den typiska användningen av idag för respektive substans. Utifrån dessa scenarier och data för bekämpningsmedlens fysiska och kemiska egenskaper, kartor över arealen åkermark, odlade grödor, klimatdata och jordarternas egenskaper simulerar modellen koncentrationer av bekämpningsmedlet i markvattnet på ca 2 meters djup, som kan ses som det vatten som infiltrerar genom den omättade zonen för att bli grundvatten. Resultaten visar inte koncentrationer i det djupare grundvattnet, för detta skulle det krävas en avancerad och högupplöst modell för grundvattenflöden för hela Skåne. De simulerade koncentrationerna i markvattnet på 2 meters djup kan därför ses som ett slags värsta-falls-antagande av möjliga halter av bekämpningsmedel som den simulerade användningen kan ge upphov till i grundvattnet. Modellresultaten pekar på att samtliga undersökta substanser skulle kunna uppnå detekterbara koncentrationer i grundvattnet på något ställe i länet. För substanserna bentazon och metazaklor visar resultaten att halter över gränsvärdet för dricksvatten (0,1 µg/l) även skulle kunna förekomma på vissa platser i länet. En summering av koncentrationerna för de simulerade substanserna visar att dricksvattengränsvärdet för summahalt bekämpningsmedel (0,5 µg/l) skulle kunna överskridas inom några mycket små områden i nordvästra och sydöstra Skåne. Generellt sett är riskerna för bekämpningsmedelsläckage till grundvattnet betydligt större i södra och västra delarna av länet, mycket beroende på den betydligt högre andelen åkermark där men också på grund av vädret i klimatzonen i detta område. Som ett beslutsunderlag för vattenförvaltningen på Länsstyrelsen har även de simulerade koncentrationerna aggregerats utifrån de grundvattenförekomster som definierats för vattenförvaltningen och som därmed ska status- och riskklassas. Beräkningar av medelvärden per grundvattenförekomst för de utvalda substanserna visar att i nästan alla fall ligger de simulerade halerna under dricksvattengränsvärdet. Simuleringar har också gjorts för historisk användning av bentazon och MCPA. Utifrån användningsdata som var typisk 1986 kan man se att det är stora skillnader i riskerna för grundvattenläckage jämfört med dagens användning. Simuleringarna med den historiska användningen resulterade i avsevärt högre koncentrationer, vilket framförallt förklaras med de betydligt högre doserna som då tilläts. En jämförelse har även genomförts mellan av modellen simulerade koncentrationer och uppmätta koncentrationer på samma plats. Dessa jämförelser tyder på att MACRO-SE i stor utsträckning kan prediktera ifall ett ämne innebär en risk för detekterbara koncentrationer i grundvattnet. Simuleringsresultaten kan dock inte visa risker av transport av bekämpningsmedel i grundvatten eller lateral transport av bekämpningsmedel från intilliggande inströmningsområden och denna faktor måste tas hänsyn till med hjälp av andra informationskällor vid riskbedömning av specifika grundvattenförekomster. Vad gäller uppskattningar av faktiska koncentrationer i grundvattnet är predikterade och uppmätta koncentrationer ofta i samma storleksordning, för de få data som finns för jämförelse, men korrelationen mellan koncentrationerna är svag. Ett bättre dataunderlag av koordinatsatta provtagningar i grundvatten på 2 meters djup skulle bidra till ett bättre test av modellen som skulle vara värdefullt för fortsatt utveckling. Resultaten från denna rapport kan användas för att peka ut de substanser som kan utgöra en risk för läckage till grundvattnet samt i vilka områden denna risk är störst. Resultaten kan även användas i Länsstyrelsens vattenförvaltningsarbete som ett underlag i påverkansbedömningen samt för att ta fram nya stationer för kontrollerande och operativa övervakning av grundvattnet och på så sätt effektivisera de regionala miljöövervakningsprogrammen. Riskkartorna kan ge information om var arbetet med grundvattenskydd behöver intensifieras, samt utgöra underlag för upprättande av nya eller revidering av äldre vattenskyddsområden.
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| 2. |
- Boye, Kristin, et al.
(author)
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Pesticide run-off to Swedish surface waters and appropriate mitigation strategies : a review of the knowledge focusing on vegetated buffer strips
- 2012
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Reports (other academic/artistic)abstract
- Environmental monitoring has revealed that pesticides regularly enter surface waters in Sweden. Mitigation measures to control point sources and spray drift have successfully reduced pesticide concentrations in natural waters, but concentrations still sometimes exceed ecotoxicological guideline values. In addition, the EU directives on water (2000/60/EC) and sustainable use of pesticides (2009/128/EC), and the regulations regarding placing plant protection products on the market (EC 1107/2009) stipulate that mitigation strategies should be developed against diffuse sources, such as surface run-off and drainage. This report presents a compilation of existing knowledge as data support for the relevant authorities in the implementation of run-off mitigation strategies in regulatory and subsidy systems. The report describes a number of measures (vegetated buffer strips in particular, but also wetlands, ditch management, integrated pest management and other management strategies) to reduce the risk of surface run-off of pesticides. The report also evaluates the validity under Swedish conditions of the R1 scenario in the PRZM-in-FOCUS model for assessing the risk of pesticide concentrations exceeding the ecotoxicological guideline values due to pesticide transport through run-off. In Sweden, the majority of surface run-off occurs during snowmelt, when pesticide losses are unlikely. The temporal and spatial incidence of run-off events during the growing season and the amount of pesticides transported in this way are currently unknown. Phosphorus models estimate that up to 33% of total annual water flow enters water courses as surface run-off in the worst case scenario, and around 10% on average, but lack of model calibration data renders these estimates highly uncertain. Field data from a drained silt loam (considered to represent the 95th percentile worst case for run-off under Swedish conditions) suggest that 35- 50% of total monthly water flow during summer (May-September) occurs as surface run-off. Thus, surface run-off may contribute considerably to pesticide transport locally, but is still considered unlikely to be of major importance on a national level, although data are lacking to confirm this assumption. Therefore, local adaptation of mitigation measures is deemed a more efficient strategy for Sweden than general solutions, such as mandatory vegetated buffer strips along all water courses. This would also simplify coupling to other environmental mitigation measures, e.g. concerning nutrients and biodiversity, and increase acceptance among farmers. The R1 scenario in PRZM-in-FOCUS greatly overestimates the risks of run-off and erosion for Sweden, since the assumptions on soil and weather conditions are more extreme than is realistic for Sweden. Thus, alternative solutions suggested in this report for assessing pesticide run-off risks in Sweden are: 1) developing a Swedish scenario for the PRZM model; 2) expanding the Swedish groundwater scenario for the MACRO-in-FOCUS model to include run-off estimation; and 3) establishing a system for local run-off mitigation that is sufficiently reliable to justify the assumption that pesticides will rarely enter surface waters through runoff. It is strongly suggested that research and monitoring projects be supported to provide a better database on which to build risk assessment scenarios and risk management strategies.
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| 3. |
- Boye, Kristin, et al.
(author)
-
Ytavrinning av växtskyddsmedel i Sverige och lämpliga motåtgärder : en kunskapssammanställning med focus på skyddszoner
- 2012
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Reports (other academic/artistic)abstract
- Ytavrinning är en av flera möjliga diffusa spridningsvägar för växtskyddsmedel till ytvatten. Motåtgärder mot ytavrinning av växtskyddsmedel, med speciellt fokus på skyddszoner, har aktualiserats genom EU:s antagande av ett nytt ramdirektiv (2009/128/EG)1 för hållbar användning av bekämpningsmedel och genom riskbedömningsrutiner vid produktregistrering av växtskyddsmedel enligt växtskyddsmedelsförordningen (EG 1107/2009)2 . Med anledning av detta har problemets omfattning i Sverige och olika motåtgärders relevans och effektivitet under svenska mark- och väderförhållanden undersökts genom en litteraturgenomgång och intervjuer med svenska och internationella aktörer och experter. Rimligheten i riskbedömningsmodelleringar med R1 scenariot i PRZM-in-FOCUS har också utvärderats för svenska förhållanden. Bedömningen är att ytavrinning lokalt kan vara av stor betydelse för transport av växtskyddsmedel till ytvatten i Sverige, men att fenomenet troligtvis är begränsat i tid och rum till tillfällen (t ex extrem nederbörd) och/eller platser (t ex erosionsbenägna jordar, traktorspår, området runt dräneringsbrunnar) där särskild risk för ytavrinning föreligger. R1- scenariots mark- och väderförhållanden är inte representativa för svensk åkermark och modelleringarna överskattar troligtvis risken för transport genom ytavrinning. Skyddszoner och andra motåtgärder bedöms effektivt kunna reducera mängden växtskyddsmedel i ytavrinning om placeringen i landskapet och utformningen är rätt. De lokala förutsättningarna i form av t ex topografi (på landskaps- och fältnivå), markegenskaper, brukningsmetoder och grödor är avgörande för vilken typ av åtgärd(er) som lämpar sig bäst och var den/de ska placeras. Att införa obligatoriska skyddszoner längs med alla vattendrag bedöms därför inte motiverat, då den förväntade effekten är låg i förhållande till de stora arealer jordbruksmark som skulle behöva tas ur produktion. Istället förespråkas lokalt anpassade åtgärder, som kan föreskrivas eller ingå i rådgivning och miljöstödssystem. Eventuellt bör ett alternativ till dagens riskbedömningsmodelleringar övervägas för att nå en rimligare försiktighetsnivå i bedömningarna.
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| 4. |
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| 5. |
- Ghafoor, Abdul, et al.
(author)
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Modeling Spatial Variation in Microbial Degradation of Pesticides in Soil
- 2011
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In: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 45, s. 6411-6419
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Journal article (peer-reviewed)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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| 6. |
- Ghafoor, Abdul, et al.
(author)
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Soil properties and susceptibility to preferential solute transport in tilled topsoil at the catchment scale
- 2013
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In: Journal of Hydrology. - : Elsevier BV. - 0022-1694 .- 1879-2707. ; 492, s. 190-199
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Journal article (peer-reviewed)abstract
- Preferential water flow and solute transport can have dramatic effects on the leaching of contaminants to groundwater and surface waters (via subsurface drainage) and is therefore of major concern to policy and decision-makers in the realm of water resources management. Unfortunately, we cannot measure these processes at the landscape scales that are relevant for management (farms, catchments, regions), which implies that an approach based on pedotransfer functions is needed to support model predictions. However, the extent to which susceptibility to preferential solute transport can be predicted from proxy site and soil attributes that can be observed and mapped at the landscape scale is still largely unknown. We therefore carried out non-reactive solute breakthrough experiments on 45 topsoil columns sampled from the contrasting soil types found in a 13 km(2) agricultural catchment in Sweden. Non-parametric indicators of preferential solute transport were derived from the shapes of the solute breakthrough curves and related to soil physical and hydraulic properties measured in the same columns. The results showed that preferential transport was weakly (and negatively) correlated with the saturated macropore hydraulic conductivity. In contrast, it was much more strongly controlled by the size of the largest water-filled pore, which in turn was significantly correlated to the saturated hydraulic conductivity of the soil matrix and soil textural classes. Preferential transport was also weakly expressed in three fine-textured soils of large organic carbon content. We conclude that the spatial pattern of preferential transport across the studied catchment should show a clear deterministic component since it depended on soil properties (e.g. clay content) that are expressed relatively uniformly across larger areas of land. (C) 2013 Elsevier B.V. All rights reserved.
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| 7. |
- Jarvis, Nicholas, et al.
(author)
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A Conceptual Model of Soil Susceptibility to Macropore Flow
- 2009
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In: Vadose Zone Journal. - : Wiley. - 1539-1663. ; 8, s. 902-910
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Journal article (peer-reviewed)abstract
- The extent to which a fast, nonequilibrium, and highly transient pore-scale process such as macropore flow can be predicted is very often debated, although little research has been conducted to investigate this issue. The validity of approaches to "upscaling" transport predictions from pore through Darcy to landscape scales critically depends on the answer to this question. We developed a simple conceptual model of soil susceptibility to macropore flow, based on a synthesis of existing experimental information. The conceptual model takes the form of a decision tree, which classifies soil horizons into one of four susceptibility classes on the basis of easily available site and soil factors. The model was tested against an independent database of tracer breakthrough experiments on undisturbed soil columns collated from the literature (n = 52), using the pore volumes drained at peak solute concentration, t(p), as a measure of the strength of macropore flow. Analysis of variance for t(p) as a function of susceptibility class showed that the overall model was significant. A significant proportion of the residual variation in t(p) could be attributed to variation in clay content within one of the susceptibility classes. Some important sources of experimental error were also Identified that may account for much of the remaining unexplained variation. We concluded that macropore flow is predictable to a sufficient degree from easily available soil properties and site factors. The simple classification tree developed in this study could be used to support hydropedological approaches to quantifying the spatial distribution of contaminant leaching at the landscape scale by providing the basis for class pedotransfer functions to estimate model parameters related to macropore flow. Such an approach has been implemented in the European project FOOTPRINT.
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| 8. |
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| 9. |
- Koestel, Johannes, et al.
(author)
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Evaluation of Nonparametric Shape Measures for Solute Breakthrough Curves
- 2011
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In: Vadose Zone Journal. - : Wiley. - 1539-1663. ; 10, s. 1261-1275
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Journal article (peer-reviewed)abstract
- A better understanding of the relationships among preferential solute transport, hydrologic boundary conditions, and site properties will help to improve predictions of the fate of contaminants in the vadose zone. The diversity of mechanisms underlying preferential transport, together with problems of nonuniqueness in fitting models to experimental data, suggests that model-independent (nonparametric) indicators of solute transport may help to establish such relationships. We therefore investigated 17 distinct nonparametric measures of solute breakthrough curve (BTC) shape using a data set of 115 tracer BTCs sampled from the literature. We tested the shape measures for sensitivity to deconvolution approaches based on Gaussian, lognormal, and gamma probability density functions and the mobile-immobile model. Furthermore, we evaluated collinearities among the 17 shape measures. Most deconvolution approaches gave very good fits to the data, with coefficients of determination larger than 0.98. Dual-domain transfer functions were superior to single-domain ones, even after accounting for measures of parsimony. The least sensitive shape measures were the normalized first temporal moment, the mean transport velocity, the apparent dispersion coefficient, and the relative arrival time of the first 5 and 85% of the tracer mass. In contrast, the skewness and kurtosis were most sensitive to the choice of deconvolution approach, even for BTC experiments with very long data series of more than eight water-filled pore volumes. The relative arrival time of the first 5% of the tracer mass was identified as the most robust shape parameter that could serve as an indicator of preferential flow and transport.
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| 10. |
- Koestel, Johannes, et al.
(author)
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Influence of soil, land use and climatic factors on the hydraulic conductivity of soil
- 2013
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In: Hydrology and Earth System Sciences. - : Copernicus GmbH. - 1027-5606 .- 1607-7938. ; 17, s. 5185-5195
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Journal article (peer-reviewed)abstract
- Due to inadequate data support, existing algorithms used to estimate soil hydraulic conductivity, K, in (eco)hydrological models ignore the effects of key site factors such as land use and climate and underplay the significant effects of soil structure on water flow at and near saturation. These limitations may introduce serious bias and error into predictions of terrestrial water balances and soil moisture status, and thus plant growth and rates of biogeochemical processes. To resolve these issues, we collated a new global database of hydraulic conductivity measured by tension infiltrometer under field conditions. The results of our analyses on this data set contrast markedly with those of existing algorithms used to estimate K. For example, saturated hydraulic conductivity, K-s, in the topsoil (<0.3m depth) was found to be only weakly related to texture. Instead, the data suggests that K-s depends more strongly on bulk density, organic carbon content and land use. In this respect, organic carbon was negatively correlated with K-s, presumably due to water repellency, while K-s at arable sites was, on average, ca. 2-3 times smaller than under natural vegetation, forests and perennial agriculture. The data also clearly demonstrates that clay soils have smaller K in the soil matrix and thus a larger contribution of soil macropores to K at and near saturation.
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| 11. |
- Koestel, Johannes, et al.
(author)
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Meta-analysis of the effects of soil properties, site factors and experimental conditions on solute transport
- 2012
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In: Hydrology and Earth System Sciences. - : Copernicus GmbH. - 1027-5606 .- 1607-7938. ; 16, s. 1647-1665
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Journal article (peer-reviewed)abstract
- Preferential flow is a widespread phenomenon that is known to strongly affect solute transport in soil, but our understanding and knowledge is still poor of the site factors and soil properties that promote it. To investigate these relationships, we assembled a database from the peer-reviewed literature containing information on 733 breakthrough curve experiments under steady-state flow conditions. Most of the collected experiments (585 of the 733 datasets) had been conducted on undisturbed soil columns, although some experiments on repacked soil, clean sands, and glass beads were also included. In addition to the apparent dispersivity, we focused our attention on three indicators of preferential solute transport: namely the 5%-arrival time, the holdback factor, and the ratio of piston-flow and average transport velocities. Our results suggest that, in contrast to the 5%-arrival time and the holdback factor, the piston-flow to transport velocity ratio is not related to preferential macropore transport but rather to the exclusion or retardation of the applied tracer. Confirming that the apparent longitudinal dispersivity is positively correlated with the travel distance of the tracer, our results also illustrate that this relationship is refined if the normalized 5%-tracer arrival time is also taken into account. In particular, we found that the degree of preferential solute transport increases with apparent dispersivity and decreases with travel distance. A similar but weaker relationship was observed between apparent dispersivity, 5%-tracer arrival time, and lateral observation scale, such that the degree of preferential transport increases with lateral observation scale. However, we also found that the travel distance and the lateral observation scale in the investigated dataset are correlated, which makes it difficult to distinguish their influence on these transport characteristics. We also found that the strength of preferential transport increased at larger flow rates and water saturations, which suggests that macropore flow was a more important flow mechanism than heterogeneous flow in the soil matrix. Nevertheless, our data show that heterogeneous flow in the soil matrix also occasionally leads to strong preferential transport. Furthermore, we show that preferential solute transport under steady-state flow depends on soil texture in a threshold-like manner: moderate to strong preferential transport was found to occur only for undisturbed soils that contain more than 8% clay. Preferential flow characteristics were also absent for columns filled with glass beads, clean sands, or sieved soil. No clear effect of land use on the pattern of solute transport could be discerned, probably because the available dataset was too small and too strongly affected by cross-correlations with experimental conditions. Our results suggest that, in developing pedotransfer functions for solute transport properties of soils, it is critically important to account for travel distance, lateral observation scale, and water flow rate and saturation.
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| 12. |
- Moeys, Julien, et al.
(author)
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Functional test of pedotransfer functions to predict water flow and solute transport with the dual-permeability model MACRO
- 2012
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In: Hydrology and Earth System Sciences. - : Copernicus GmbH. - 1027-5606 .- 1607-7938. ; 16, s. 2069-2083
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Journal article (peer-reviewed)abstract
- Abstract. Estimating pesticide leaching risks at the regional scale requires the ability to completely parameterise a pesticide fate model using only survey data, such as soil and land-use maps. Such parameterisations usually rely on a set of lookup tables and (pedo)transfer functions, relating elementary soil and site properties to model parameters. The aim of this paper is to describe and test a complete set of parameter estimation algorithms developed for the pesticide fate model MACRO, which accounts for preferential flow in soil macropores. We used tracer monitoring data from 16 lysimeter studies, carried out in three European countries, to evaluate the ability of MACRO and this "blind parameterisation" scheme to reproduce measured solute leaching at the base of each lysimeter. We focused on the prediction of early tracer breakthrough due to preferential flow, because this is critical for pesticide leaching. We then calibrated a selected number of parameters in order to assess to what extent the prediction of water and solute leaching could be improved. Our results show that water flow was generally reasonably well predicted (median model efficiency, ME, of 0.42). Although the general pattern of solute leaching was reproduced well by the model, the overall model efficiency was low (median ME = −0.26) due to errors in the timing and magnitude of some peaks. Preferential solute leaching at early pore volumes was also systematically underestimated. Nonetheless, the ranking of soils according to solute loads at early pore volumes was reasonably well estimated (concordance correlation coefficient, CCC, between 0.54 and 0.72). Moreover, we also found that ignoring macropore flow leads to a significant deterioration in the ability of the model to reproduce the observed leaching pattern, and especially the early breakthrough in some soils. Finally, the calibration procedure showed that improving the estimation of solute transport parameters is probably more important than the estimation of water flow parameters. Overall, the results are encouraging for the use of this modelling set-up to estimate pesticide leaching risks at the regional-scale, especially where the objective is to identify vulnerable soils and "source" areas of contamination.
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| 13. |
- Moeys, Julien
(author)
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Modelling pesticides leaching in cropping systems: Effect of uncertainties in climate, agricultural practices, soil and pesticide properties
- 2018
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In: Environmental Modelling and Software. - : Elsevier BV. - 1364-8152 .- 1873-6726. ; 109, s. 342-352
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Journal article (peer-reviewed)abstract
- Modelling of pesticide leaching is paramount to managing the environmental risks associated with the chemical protection of crops, but it involves large uncertainties in relation to climate, agricultural practices, soil and pesticide properties. We used Latin Hypercube Sampling to estimate the contribution of these input factors with the STICS-MACRO model in the context of a 400 km(2) catchment in France, and two herbicides applied to maize: bentazone and S-metolachlor. For both herbicides, the most influential input factors on modelling of pesticide leaching were the inter-annual variability of climate, the pesticide adsorption coefficient and the soil boundary hydraulic conductivity, followed by the pesticide degradation half-life and the rainfall spatial variability. This work helps to identify the factors requiring greater accuracy to ensure better pesticide risk assessment and to improve environmental management and decision-making processes by quantifying the probability and reliability of prediction of pesticide concentrations in groundwater with STICS-MACRO.
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| 14. |
- Moeys, Julien
(author)
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Pedotransfer functions for isoproturon sorption on soils and vadose zone materials
- 2011
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In: Pest Management Science. - : Wiley. - 1526-498X .- 1526-4998. ; 67, s. 1309–1319-
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Journal article (peer-reviewed)abstract
- BACKGROUND: Sorption coefficients (the linear KD or the non-linear KF and NF) are critical parameters in models of pesticide transport to groundwater or surface water. In this work, a dataset of isoproturon sorption coefficients and corresponding soil properties (264 KD and 55 KF) was compiled, and pedotransfer functions were built for predicting isoproturon sorption in soils and vadose zone materials. These were benchmarked against various other prediction methods. RESULTS: The results show that the organic carbon content (OC) and pH are the two main soil properties influencing isoproturon KD. The pedotransfer function is KD = 1.7822 + 0.0162 OC1.5 - 0.1958 pH (KD in L kg-1 and OC in g kg-1). For low-OC soils (OC < 6.15 g kg-1), clay and pH are most influential. The pedotransfer function is then KD = 0.9980 + 0.0002 clay - 0.0990 pH (clay in g kg-1). Benchmarking KD estimations showed that functions calibrated on more specific subsets of the data perform better on these subsets than functions calibrated on larger subsets. CONCLUSION: Predicting isoproturon sorption in soils in unsampled locations should rely, whenever possible, and by order of preference, on (a) site- or soil-specific pedotransfer functions, (b) pedotransfer functions calibrated on a large dataset, (c) KOC values calculated on a large dataset or (d) KOC values taken from existing pesticide properties databases. Copyright © 2011 Society of Chemical Industry
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| 15. |
- Moeys, Julien
(author)
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Sensitivity analysis of the STICS-MACRO model to identify cropping practices reducing pesticides losses
- 2017
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In: Science of the Total Environment. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; 580, s. 117-129
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Journal article (peer-reviewed)abstract
- STICS-MACRO is a process-based model simulating the fate of pesticides in the soil-plant system as a function of agricultural practices and pedoclimatic conditions. The objective of this work was to evaluate the influence of crop management practices on water and pesticide flows in contrasted environmental conditions. We used the Morris screening sensitivity analysis method to identify the most influential cropping practices. Crop residues management and tillage practices were shown to have strong effects on water percolation and pesticide leaching. In particular, the amount of organic residues added to soil was found to be the most influential input. The presence of a mulch could increase soil water content so water percolation and pesticide leaching. Conventional tillage was also found to decrease pesticide leaching, compared to no-till, which is consistent with many field observations. The effects of the soil, crop and climate conditions tested in this work were less important than those of cropping practices. STICS-MACRO allows an ex ante evaluation of cropping systems and agricultural practices, and of the related pesticides environmental impacts. (C) 2016 Elsevier B.V. All rights reserved.
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| 16. |
- Moeys, Julien, et al.
(author)
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Sequential use of the STICS crop model and of the MACRO pesticide fate model to simulate pesticides leaching in cropping systems
- 2017
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In: Environmental Science and Pollution Research. - : Springer Science and Business Media LLC. - 0944-1344 .- 1614-7499. ; 24, s. 6895-6909
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Journal article (peer-reviewed)abstract
- The current challenge in sustainable agriculture is to introduce new cropping systems to reduce pesticides use in order to reduce ground and surface water contamination. However, it is difficult to carry out in situ experiments to assess the environmental impacts of pesticide use for all possible combinations of climate, crop, and soils; therefore, in silico tools are necessary. The objective of this work was to assess pesticides leaching in cropping systems coupling the performances of a crop model (STICS) and of a pesticide fate model (MACRO). STICS-MACRO has the advantage of being able to simulate pesticides fate in complex cropping systems and to consider some agricultural practices such as fertilization, mulch, or crop residues management, which cannot be accounted for with MACRO. The performance of STICS-MACRO was tested, without calibration, from measurements done in two French experimental sites with contrasted soil and climate properties. The prediction of water percolation and pesticides concentrations with STICS-MACRO was satisfactory, but it varied with the pedoclimatic context. The performance of STICS-MACRO was shown to be similar or better than that of MACRO. The improvement of the simulation of crop growth allowed better estimate of crop transpiration therefore of water balance. It also allowed better estimate of pesticide interception by the crop which was found to be crucial for the prediction of pesticides concentrations in water. STICS-MACRO is a new promising tool to improve the assessment of the environmental risks of pesticides used in cropping systems.
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| 18. |
- Steffens, Karin Anna, et al.
(author)
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Direct and indirect effects of climate change on herbicide leaching - A regional scale assessment in Sweden
- 2015
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In: Science of the Total Environment. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; 514, s. 239-249
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Journal article (peer-reviewed)abstract
- Climate change is not only likely to improve conditions for crop production in Sweden, but also to increase weed pressure and the need for herbicides. This study aimed at assessing and contrasting the direct and indirect effects of climate change on herbicide leaching to groundwater in a major crop production region in south-west Sweden with the help of the regional pesticide fate and transport model MACRO-SE. We simulated 37 out of the 41 herbicides that are currently approved for use in Sweden on-eight major crop types for the 24 most common soil types in the region. The results were aggregated accounting for the fractional coverage of the crop and the area sprayed with a particular herbicide. For simulations of the future, we used projections of five different climate models as model driving data and assessed three different future scenarios: (A) only changes in climate, (B) changes in climate and land-use (altered crop distribution), and (C) changes in climate, land-use, and an increase in herbicide use. The model successfully distinguished between leachable and non-leachable compounds (88% correctly classified) in a qualitative comparison against regional-scale monitoring data. Leaching was dominated by only a few herbicides and crops under current climate and agronomic conditions. The model simulations suggest that the direct effects of an increase in temperature, which enhances degradation, and precipitation which promotes leaching, cancel each other at a regional scale, resulting ifs a slight decrease in leachate concentrations in a future climate. However, the area at risk of groundwater contamination doubled when indirect effects of changes in land-use and herbicide use, were considered. We therefore concluded that it is important to consider the indirect effects of climate change alongside the direct effects and that effective mitigation strategies and strict regulation are required to secure future (drinking) water resources. (C) 2014 Elsevier B.V. All rights reserved.
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| 20. |
- Steffens, Karin Anna, et al.
(author)
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Modelling pesticide leaching under climate change: parameter vs. climate input uncertainty
- 2014
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In: Hydrology and Earth System Sciences. - : Copernicus GmbH. - 1027-5606 .- 1607-7938. ; 18, s. 479-491
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Journal article (peer-reviewed)abstract
- Assessing climate change impacts on pesticide leaching requires careful consideration of different sources of uncertainty. We investigated the uncertainty related to climate scenario input and its importance relative to parameter uncertainty of the pesticide leaching model. The pesticide fate model MACRO was calibrated against a comprehensive one-year field data set for a well-structured clay soil in southwestern Sweden. We obtained an ensemble of 56 acceptable parameter sets that represented the parameter uncertainty. Nine different climate model projections of the regional climate model RCA3 were available as driven by different combinations of global climate models (GCM), greenhouse gas emission scenarios and initial states of the GCM. The future time series of weather data used to drive the MACRO model were generated by scaling a reference climate data set (1970-1999) for an important agricultural production area in south-western Sweden based on monthly change factors for 2070-2099. 30 yr simulations were performed for different combinations of pesticide properties and application seasons. Our analysis showed that both the magnitude and the direction of predicted change in pesticide leaching from present to future depended strongly on the particular climate scenario. The effect of parameter uncertainty was of major importance for simulating absolute pesticide losses, whereas the climate uncertainty was relatively more important for predictions of changes of pesticide losses from present to future. The climate uncertainty should be accounted for by applying an ensemble of different climate scenarios. The aggregated ensemble prediction based on both acceptable parameterizations and different climate scenarios has the potential to provide robust probabilistic estimates of future pesticide losses.
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