BIOTIC AND ABIOTIC DEGRADATION RATES OF METHYL PARATHION IN FRESH-WATER AND ESTUARINE WATER AND SEDIMENT SAMPLES

Statistical analysis of degradation rates of methyl parathion samples from two Gulf Coast [USA] estuaries over a three-year period indicated that biodegradation occurred in the presence of sediment but was insignificant in water. Sediment rates always showed the same relative five-fold difference at a primary site within each estuarine area. Samples from 11 ancillary sites indicated biodegradation rates in sediments can be subdivided into two groupings which were independent of seasonal differences (excluding temperature). Spatial variations in rates, therefore, may be of minor environmental significance for this chemical in estuarine areas.