Sandy soils, chlordane residues

The half-life of chlordane in soil is approximately 4 years. Residues of this highly persistent chemical have been found in excess of 10% of the initially applied amount 10 years or more after application. Chlordane does not chemically degrade nor does it biodegrade in soils. Chlordane binds rapidly to soil particles and stays adsorbed to clay soil. Combined with its insolubility in water, this produces a low potential for ground water contamination. Sandy soil, on the other hand, allows chlordane to pass into ground water. 

Table V shows residue levels of chlordane and heptachlor in soils and air, respectively, from crawl-space constructed dwellings built on sandy soils. Soil residues of chlordane and heptachlor in the 0 to 10-cm depth averaged 1052 (15 samples) and 414 ppm (seven samples) respectively, and in the 10 to 20-cm depth 204 (eight samples) and 82 ppm (one sample), respectively.

Air of eight of the rooms sampled during the study contained chlordane residues above the recommended 5.0 pg/m limit. Five of these rooms were from houses treated in 1983, two were from houses treated in 1980, and one was from a 1979-treated house. Both the kitchen and bedroom in a 1983-treated home (crawl-space construction on sandy soil) were higher than the recommended level, while the other six rooms were in six different dwellings. The air concentrations iti these rooms ranged from 5.3 to 9.9 pg/m3. 

Table V. Chlordane and Heptachlor Residues in Sandy Soils and... 

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