title: Integration of transport concepts for risk assessment of pesticide erosion.
abstract: Environmental contamination by agrochemicals has been a large problem for decades. Pesticides are transported in runoff and remain attached to eroded soil particles, posing a risk to water and soil quality and human health. We have developed a parsimonious integrative model of pesticide displacement by runoff and erosion that explicitly accounts for water infiltration, erosion, runoff, and pesticide transport and degradation in soil. The conceptual framework was based on broadly accepted assumptions such as the convection-dispersion equation and lognormal distributions of soil properties associated with transport, sorption, degradation, and erosion. To illustrate the concept, a few assumptions are made with regard to runoff in relatively flat agricultural fields: dispersion is ignored and erosion is modelled by a functional relationship. A sensitivity analysis indicated that the total mass of pesticide associated with soil eroded by water scouring increased with slope, rain intensity, and water field capacity of the soil. The mass of transported pesticide decreased as the micro-topography of the soil surface became more distinct. The timing of pesticide spraying and rate of degradation before erosion negatively affected the total amount of transported pesticide. The mechanisms involved in pesticide displacement, such as runoff, infiltration, soil erosion, and pesticide transport and decay in the topsoil, were all explicitly accounted for, so the mathematical complexity of their description can be high, depending on the situation.
authors.affiliation: Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan 430074, China; Soil Physics and Land Management, Wageningen University, P.O. Box 47, 6700 AA Wageningen, The Netherlands. Electronic address: xiaomei.yang@wur.nl.
authors.forename: Xiaomei
authors.initials: X
authors.lastname: Yang
authors.affiliation: Soil Physics and Land Management, Wageningen University, P.O. Box 47, 6700 AA Wageningen, The Netherlands; School of Chemistry, Monash University, Melbourne, VIC 3800, Australia.
authors.forename: Sjoerd E A T M
authors.initials: SE
authors.lastname: Van Der Zee
authors.affiliation: Soil Physics and Land Management, Wageningen University, P.O. Box 47, 6700 AA Wageningen, The Netherlands.
authors.forename: Lingtong
authors.initials: L
authors.lastname: Gai
authors.affiliation: Soil Physics and Land Management, Wageningen University, P.O. Box 47, 6700 AA Wageningen, The Netherlands.
authors.forename: Jan G
authors.initials: JG
authors.lastname: Wesseling
authors.affiliation: Soil Physics and Land Management, Wageningen University, P.O. Box 47, 6700 AA Wageningen, The Netherlands.
authors.forename: Coen J
authors.initials: CJ
authors.lastname: Ritsema
authors.affiliation: Soil Physics and Land Management, Wageningen University, P.O. Box 47, 6700 AA Wageningen, The Netherlands; Institute of Crop Science and Resources Conservation (INRES), University of Bonn, 53115 Bonn, Germany.
authors.forename: Violette
authors.initials: V
authors.lastname: Geissen
mesh_terms: D004784:Environmental Monitoring; D010575:Pesticides / Q000032:analysis*; D018570:Risk Assessment; D012987:Soil; D012989:Soil Pollutants / Q000032:analysis*; D014872:Water Movements; D014874:Water Pollutants, Chemical / Q000032:analysis
chemical_list: D010575:Pesticides; D012987:Soil; D012989:Soil Pollutants; D014874:Water Pollutants, Chemical
keywords: Erosion; Pesticide; Sensitivity analysis; Transport model