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Field Investigations and Modeling of Particle‐Facilitated Pesticide Transport in Macroporous Soil
Author(s) -
Villholth Karen G.,
Jarvis Nicholas J.,
Jacobsen Ole H.,
Jonge Hubert
Publication year - 2000
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq2000.00472425002900040037x
Subject(s) - particulates , soil water , leaching (pedology) , sorption , pesticide , particle (ecology) , environmental chemistry , chemistry , pesticide degradation , loam , desorption , environmental science , environmental engineering , soil science , adsorption , geology , agronomy , oceanography , biology , organic chemistry
Physical and chemical non‐equilibrium processes may facilitate the transport of pesticides and other chemicals through structured and macroporous soils. For sorbing pesticides, transport associated with a mobile colloidal or particulate phase represents an additional transport mechanismin structured soils that is not well understood. We investigated particle‐facilitated transport of a sorbing pesticide (prochloraz, N ‐propyl‐ N ‐[2‐(2,4,6‐trichlorophenoxy)ethyl]imidazole‐1‐carboxamide) in a 5‐ by 5‐m subsurface‐drained field plot in a structured sandy loam in Denmark. Following pesticide application, three simulated rainfall events during an 8‐d period were monitored in terms of drainage flow rate, content of particulate matter (>0.24 µm), and pesticide concentration in the solution and in the particulate phases in the drainage water. The fraction of pesticide loss to the drain was 0.2% of the applied mass, of which 6% was associated with the particulate phase. Macroporous flow paths appeared to be major routes of pesticide and particle transport. Preferential sorption to particles in the drainage water relative to bulk soil, and possibly also slow desorption from the particles, were assumed to influence the pesticide leaching in the particulate fraction. Based on experimental and reported data, the dual‐porosity model MACRO, modified to account for particle mobilization and transport, could be calibrated to simulate the observations. Sensitive parameters for the particle and pesticide descriptions were identified.