TY - JOUR

T1 - Physico-chemical characteristics affect the spatial distribution of pesticide and transformation product loss to an agricultural brook

AU - Gassmann, M.

AU - Olsson, O.

AU - Stamm, C.

AU - Weiler, M.

AU - Kümmerer, K.

PY - 2015/11/1

Y1 - 2015/11/1

N2 - Diffuse entry of pesticide residues from agriculture into rivers is spatially unevenly distributed. Therefore, the identification of critical source areas (CSAs) may support water quality management in agricultural catchments. In contrast to former studies, we followed the hypothesis that not only hydrological and topographical characteristics but also physico-chemical properties of pesticide residues have a major influence on their loss to rivers and on corresponding formation of CSAs. We designed a virtual experiment, i.e. a numerical experiment as close as possible to environmental conditions, in a headwater catchment where pronounced spatial differences in hydrological transport processes were identified in the past. 144 scenarios with different combinations of adsorption coefficients (KOC=10-1000ml/g) and transformation half-lives (DT50=3-60days) for pesticide parent compounds (PCs) and their transformation products (TPs) were simulated using the catchment-scale spatially distributed reactive transport model ZIN-AgriTra.Export fractions of substances in the virtual experiment ranged from 0.001-15% for pesticides and 0.001-1.8% for TPs. The results of the scenario investigations suggest that more of the calculated export mass variability could be attributed to KOC than to DT50 for both PCs and TPs. CSAs for TPs were spatially more equally distributed in the catchment than for PC export which was likely an effect of changing physico-chemical properties during transformation. The ranking of highest export fields was different between PCs and TPs for most of the investigated scenarios but six fields appeared among the top ten export fields in 95% of the scenarios, which shows the influence of site characteristics such as tile drains or soil properties in the catchment. Thus, the highest export fields were determined by a combination of site characteristics and substance characteristics. Therefore, despite the challenge of widely differing physico-chemical characteristics of pesticides on the market, these characteristics are an important consideration when delineating pesticide residue CSAs.

AB - Diffuse entry of pesticide residues from agriculture into rivers is spatially unevenly distributed. Therefore, the identification of critical source areas (CSAs) may support water quality management in agricultural catchments. In contrast to former studies, we followed the hypothesis that not only hydrological and topographical characteristics but also physico-chemical properties of pesticide residues have a major influence on their loss to rivers and on corresponding formation of CSAs. We designed a virtual experiment, i.e. a numerical experiment as close as possible to environmental conditions, in a headwater catchment where pronounced spatial differences in hydrological transport processes were identified in the past. 144 scenarios with different combinations of adsorption coefficients (KOC=10-1000ml/g) and transformation half-lives (DT50=3-60days) for pesticide parent compounds (PCs) and their transformation products (TPs) were simulated using the catchment-scale spatially distributed reactive transport model ZIN-AgriTra.Export fractions of substances in the virtual experiment ranged from 0.001-15% for pesticides and 0.001-1.8% for TPs. The results of the scenario investigations suggest that more of the calculated export mass variability could be attributed to KOC than to DT50 for both PCs and TPs. CSAs for TPs were spatially more equally distributed in the catchment than for PC export which was likely an effect of changing physico-chemical properties during transformation. The ranking of highest export fields was different between PCs and TPs for most of the investigated scenarios but six fields appeared among the top ten export fields in 95% of the scenarios, which shows the influence of site characteristics such as tile drains or soil properties in the catchment. Thus, the highest export fields were determined by a combination of site characteristics and substance characteristics. Therefore, despite the challenge of widely differing physico-chemical characteristics of pesticides on the market, these characteristics are an important consideration when delineating pesticide residue CSAs.

KW - Chemistry

KW - Catchment scale

KW - Critical source areas

KW - Metabolite

KW - Virtual experiment

KW - ZIN-AgriTra model

UR - http://www.scopus.com/inward/record.url?scp=84934990291&partnerID=8YFLogxK

U2 - 10.1016/j.scitotenv.2015.06.068

DO - 10.1016/j.scitotenv.2015.06.068

M3 - Journal articles

C2 - 26119387

AN - SCOPUS:84934990291

VL - 532

SP - 733

EP - 743

JO - The Science of The Total Environment

JF - The Science of The Total Environment

SN - 0048-9697

ER -