Fate and transport of ethoprophos in the Jamaican environment

The hydrolytic half lives of ethoprophos in distilled, river, brackish and open sea water were 25, 133, 65 and 81 days, respectively. Under laboratory conditions, volatilisation of the residues after 12 h was 1.4-3.6, 2.3-4.5 and 6.5-20.2% from a sandy loam soil with 1, 10 and 20% moisture levels, r espectively. Photolysis in soil was significantly faster (P < 0.05) in dire ct sunlight (T-1/2 of 4.7 days) than in the shade (T-1/2 of 12.3 days). The microbial degradation of ethoprophos was more than two-fold faster in unst erile soil (T-1/2 of 10.9 days) than in sterile soil (T-1/2 of 28.8 days). The runoff of ethoprophos from unweeded plantation soil at 23 degrees slope was significantly (P = 0.015) less than at 38 degrees slope: the amounts l ost after 9 weeks and 27.5 mm of rainfall were 89.4 and 91.2 degrees, respe ctively, of the applied amount from the two respective slopes. In the weede d plots, 93.6 and 92.4% of the applied insecticide were lost from 23 degree s and 38 degrees slopes, respectively. Under laboratory conditions, between 67.0 and 85.1% of ethoprophos leached through the soil columns. Under fiel d conditions, after 9 weeks and 25 mm of rainfall, only 2.8 and 2.0% residu es were recovered at a depth of 10-15 cm from unweeded and weeded slopes, r espectively at 23 degrees slope, and 2.2 and 1.9% from the two respective p lots at 38 degrees slope. (C) 1999 Elsevier Science B.V. All rights reserve d.