12,000

We have over 12,000 students, from over 100 countries, within one of the safest campuses in the UK

93%

93% of Lancaster students go into work or further study within six months of graduating

Home > Research > Publications & Outputs > Chiral organochlorine pesticide signatures in g...
View graph of relations

« Back

Chiral organochlorine pesticide signatures in global background soils.

Research output: Contribution to journalJournal article

Published

Journal publication date15/11/2005
JournalEnvironmental Science and Technology
Journal number22
Volume39
Number of pages7
Pages8671-8677
Original languageEnglish

Abstract

Chiral pesticides frequently undergo enantioselective degradation in soils. Prior studies to characterize chiral signatures have focused on treated agricultural soils, rather than background (untreated) soils, and tracking signatures in the atmosphere for source apportionment purposes. In this study, we investigated the chiral signatures in 65 background soils collected from different locations across the world. The soils were taken from different ecosystems (e.g., grasslands, forests), and the enantiomeric fractions (EFs) of chiral chlordanes, α-hexachlorocyclohexane (α-HCH), and o,p‘-DDT were determined. Chlordanes in most of the soils showed the usual pattern of enantioselective degradation seen in agricultural soils, depletion of (+)-trans-chlordane (TC) and (−)-cis-chlordane (CC). However, some samples showed opposite enantiomer degradation patterns for TC, CC, and chlordane compound MC5. Correlations were tested between the deviation of EFs from racemic (DEVrac = absolute value of 0.500 − EF), the percent soil organic matter (% SOM), annual mean temperature, and the ratio of TC to the more stable compound trans-nonachlor (TN). Significant positive correlations were found between DEVrac and % SOM for TC and CC (p = 0.0022 and 0.0031), but not for the other OCPs. No significant correlations were found between DEVrac and annual mean temperature for any of the OCPs. DEVrac for TC was negatively correlated with the TC/TN ratio, but the regression was driven by two points with high ratios of TC/CC. Removing these two points resulted in a nonsignificant regression. The range of EFs for TC, CC, and α-HCH in soils was greater than in ambient air, providing evidence of in situ degradation after atmospheric deposition in some cases. Variable EFs in soil suggest that caution is needed when considering the enantiomer signatures in air as a marker of volatilization of weathered soil-derived organochlorines.