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Dissolved organic carbon interactions with sorption and leaching of diuron in organic‐amended soils
Author(s) -
Cox L.,
Velarde P.,
Cabrera A.,
Hermosín M. C.,
Cornejo J.
Publication year - 2007
Publication title -
european journal of soil science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.244
H-Index - 111
eISSN - 1365-2389
pISSN - 1351-0754
DOI - 10.1111/j.1365-2389.2006.00856.x
Subject(s) - sorption , amendment , leaching (pedology) , dissolved organic carbon , environmental chemistry , chemistry , soil water , organic matter , total organic carbon , soil science , environmental science , adsorption , organic chemistry , political science , law
Summary Diuron ( N ′‐[3,4‐dichlorophenyl]‐ N,N ‐dimethylurea) is one of the most frequently used herbicides in olive groves in Spain and other Mediterranean countries. The main objective of this work was to investigate the effect of the dissolved organic carbon (DOC) from a commercial humic amendment, derived by composting the liquid waste of the olive‐mill process (LF), and a solid residue from the olive oil production industry (AL) on the sorption and leaching behaviour of diuron in soil. For this purpose, a clay and a sandy soil were selected. Soil sorption coefficients of diuron increased with LF (32%) and AL (76%) amendment in the sandy soil, whereas sorption decreased in the clay soil upon amendment, especially in the case of the liquid LF (52%). The DOC from LF and AL is composed of very poorly humified molecules, which are strongly sorbed onto the clay soil and thus compete with diuron for the same sorption sites. Dialysis experiments revealed that diuron forms stable complexes with DOC from LF and AL. Leaching of diuron in columns of the sandy soil treated with the organic amendments caused earlier breakthrough and maximum concentration peaks at fewer pore volumes when compared with leaching with 0.01 m CaCl 2 . Competition between diuron and DOC molecules for sorption sites and diuron–DOC interactions can both account for the enhanced leaching of diuron.