| 1. |
- Boye, Kristin, et al.
(författare)
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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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Rapport (övrigt vetenskapligt/konstnärligt)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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| 2. |
- Boye, Kristin, et al.
(författare)
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Ytavrinning av växtskyddsmedel i Sverige och lämpliga motåtgärder : en kunskapssammanställning med focus på skyddszoner
- 2012
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Rapport (övrigt vetenskapligt/konstnärligt)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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| 3. |
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| 4. |
- Koestel, Johannes, et al.
(författare)
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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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Ingår i: Hydrology and Earth System Sciences. - : Copernicus GmbH. - 1027-5606 .- 1607-7938. ; 16, s. 1647-1665
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Tidskriftsartikel (refereegranskat)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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| 5. |
- Moeys, Julien, et al.
(författare)
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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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Ingår i: Hydrology and Earth System Sciences. - : Copernicus GmbH. - 1027-5606 .- 1607-7938. ; 16, s. 2069-2083
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Tidskriftsartikel (refereegranskat)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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