1 research outputs found
Compound Specific and Enantioselective Stable Isotope Analysis as Tools To Monitor Transformation of Hexachlorocyclohexane (HCH) in a Complex Aquifer System
Technical
hexachlorocyclohexane (HCH) mixtures and Lindane (γ-HCH)
have been produced in Bitterfeld-Wolfen, Germany, for about 30 years
until 1982. In the vicinity of the former dump sites and production
facilities, large plumes of HCHs persist within two aquifer systems.
We studied the natural attenuation of HCH in these groundwater systems
through a combination of enantiomeric and carbon isotope fractionation
to characterize the degradation of α-HCH in the areas downstream
of a former disposal and production site in Bitterfeld-Wolfen. The
concentration and isotope composition of α-HCH from the Quaternary
and Tertiary aquifers were analyzed. The carbon isotope compositions
were compared to the source signal of waste deposits for the dumpsite
and highly contaminated areas. The average value of δ<sup>13</sup>C at dumpsite was −29.7 ± 0.3 ‰ and −29.0
± 0.1 ‰ for (−) and (+)Âα-HCH, respectively,
while those for the β-, γ-, δ-HCH isomers were −29.0
± 0.3 ‰, −29.5 ± 0.4 ‰, and −28.2
± 0.2 ‰, respectively. In the plume, the enantiomer fraction
shifted up to 0.35, from 0.50 at source area to 0.15 (well T1), and
was found accompanied by a carbon isotope enrichment of 5 ‰
and 2.9 ‰ for (−) and (+)Âα-HCH, respectively.
The established model for interpreting isotope and enantiomer fractionation
patterns showed potential for analyzing the degradation process at
a field site with a complex history with respect to contamination
and fluctuating geochemical conditions