FATE OF ENDOSULFAN IN SOIL AND IN RIVER AND COASTAL WATERS OF JAMAICA

摘要

The runoff, leaching, volatilization and degradation of endosulfan were studied in a coffee plantation in sterilized and unsterilized soils, and in river and coastal waters from closed (harbour) and open seas. After 9 weeks and 27.5 mm of precipitation, the runoff of endosulfan was significantly (P = 0.05) higher in weeded than in unweeded plots, and at the of 23° and 38° slopes than at the 5° slope. The percentage losses of residues at the origin of the slopes in weeded and unweeded (data in parentheses) plots were 33.5 (27.8) at the 5° slope, 60.5 (53.9) at the 23° slope, and 59.9 (56.6) at the 38° slope. The percentage residues recovered at various points along the 6 m slopes were 0.42 (0.28) at the 5° slope, 2.4 (3.17) at the 23° slope, and 1.83 (2.98) at the 38° slope. Leaching was significantly (P = 0.032) higher at the 5° slope than at the 23° and 38° slopes, and in the unweeded plots than in the weeded plots. At the origin, the percentage leaching at depths of 10-15 cm at the 5°, 23° and 38° slopes in weeded and unweeded plots were 3.5 (5.9), 1.02 (2.0) and 0.86 (0.92), respectively. Volatilization in 12 hours was 17.4 + 0.42%, 19.8 ± 0.79% and 22.4 + 0.88% at the 5, 10 and 20% moisture levels, respectively. The hydrolytic rates (half-life in days) in distilled, river, open sea and closed sea waters were 27.5, 260.3, 303.2 and 104.9, respectively, for alpha-endosulfan, and 23.5, 547.5, 151.5 and 86.9, respectively, for beta-endosulfan. Photolysis in the soil was significantly (P < 0.001) lower in complete darkness, tree shade and direct sunlight; the half-life values were 215.8, 28.5 and 25.2 days, respectively, for alpha-endosulfan, and 181.3, 24.5 and 8.7 days, respectively, for beta-endosulfan. Microbial degradation in the unsterilized soil was not significantly (P > 0.05) different from that in the sterilized soil.