Open AccessAn Inquiry into the Phenomenon of Enhanced Transport of Pesticides Caused by Effluents
Author(s) -
Ellen R. Graber,
Linda Lee,
Mikhail Borisover
Publication year - 1995
Language(s) - English
Resource type - Reports
DOI - 10.32747/1995.7570559.bard
Subject(s) - effluent , chemistry , pesticide , environmental chemistry , soil water , alkalinity , dissolved organic carbon , organic matter , environmental engineering , environmental science , soil science , agronomy , organic chemistry , biology
The objective of this collaborative research project was to determine the factors that may cause enhanced pesticide transport under effluent irrigation. For s-triazines, the potential for enhanced transport through association with effluent dissolved organic matter (OM) was shown to be small in batch and column studies and in numerical simulations. High alkalinity and pH of treated effluents increased soil-solution pH for selected soil-effluent combinations, promoting the dissolution of soil OM and mobilizing otherwise OM-retained pesticides. Evapotranspiration in column studies resulted in increased pore-water concentrations of dissolved OM and some pesticide transport enhancement with the greatest effect observed with OM-poor soils. For ionogenic pesticides, effluent-induced increases in soil-solution pH increased the mobility of pesticides with acid dissociation constants within 2 pH units of the initial soil-solution pH. Effluents high in suspended solids and/or monovalent cations resulted in blockage of soil pores reducing water-flow velocity and/or changing flow paths. Reduced flow resulted in an increase in desorption time of soil sorbed pesticides, increasing the amount available for further transport with the net effect being soil texture dependent. In terms of pesticide degradation in soils, effluents appeared to have only a minor effect for the few pesticides investigated.