Compositional and chiral profiles of weathered chlordane residues in soil.

The fate of chlordane and other persistent organic pollutants in the environment is of international concern. The behavior of persistent organic pollutants under both abiotic and biotic conditions must be determined for the comprehensive elucidation of their cycling through the biosphere. Standard analytical methods such as gas chromatography with electron capture detection are adequate for studies of cycling under abiotic conditions. Since two of the main components of technical chlordane, cis-chlordane and trans-chlordane, are optically active, chiral gas chromatography can be used to study the impact of biotic influences on chlordane's fate. We report here the use of chiral gas chromatography interfaced with ion trap mass spectrometry as part of an analytically rigorous method for the simultaneous determination of the compositional and chiral profiles of weathered soil residues of technical chlordane. Using the method described, several patterns in the long-term weathering of technical chlordane in soil are observed.

Chlordane uptake and its translocation in food crops.

Chlordane is a member of the persistent organic pollutants (POPs), a group of chemicals characterized by extremely long residence in the environment after application. Technical chlordane, composed of a large number of components, is a synthetic organochlorine substance that was used primarily as an insecticide. Uptake by root crops of persistent soil residues of chlordane was noted early in the chronology of the material. The present report is the first comprehensive study of the uptake of weathered soil residues of chlordane and its translocation throughout the tissues of food crops under both greenhouse and field conditions. The data show that for all 12 crops chlordane is not limited to root tissue but is translocated from the root to some of the aerial tissues. Chlordane accumulation in edible aerial tissue appears to be dependent on plant physiology. As expected, chlordane was detected in the edible root tissue of the three root crops examined, carrots, beets, and potatoes. In the remaining crops chlordane was detected in the edible aerial tissue of spinach, lettuce, dandelion, and zucchini, whereas it was not detected in edible aerial tissue of tomatoes, peppers, and corn; trace amounts of chlordane were detected in the edible aerial tissue of bush beans and eggplant. Under the conditions of the field trial the data indicate that for weathered chlordane residues, the soil-to-plant uptake route dominates over the air-to-plant uptake route. This is the case even when the soil concentration of the recalcitrant, weathered residues, for which volatilization is expected to be minimal, is as high as it would be directly following application. Greenhouse trials confirm this observation for zucchini, a member of the Cucurbitaceae family, which bioaccumulates weathered chlordane very efficiently in its edible fruits.