Spatial and temporal distribution of chiral pesticides in Calanus spp. from three Arctic fjords

Concentration and enantiomeric fractions (EFs) of chiral chlorinated pesticides (α-hexachlorocyclohexane (α-HCH), trans-, cis- and oxychlordane) were determined in Arctic zooplankton, mainly Calanus spp. collected in the period 2007–11 from Svalbard fjords and open pack-ice. The temporal and spatial enantiomer distribution varied considerably for all species and chiral pesticides investigated. An overall enantiomeric excess of (+)-oxychlordane (EF 0.53–0.86) were observed. Cis-chlordane was close to racemic (EF 0.46–0.55), while EF for trans-chlordane varied between 0.29 and 0.55, and between 0.38 and 0.59 for α-HCH. The biodegradation potential for trans-chlordane was higher compared to cis-chlordane. The comprehensive statistical evaluation of the data set revealed that the EF distribution of α-HCH was affected by ice cover to a higher extent compared to cis-chlordane. Potential impact from benthic processes on EFs in zooplankton is an interesting feature and should be further investigated. Enantiomeric selective analyses may be a suitable tool for investigations of climate change related influences on Arctic ecosystems. [Display omitted] •Largest spatial and temporal data set of chiral pesticides in Arctic zooplankton.•Chiral chlordane and α-HCH are useful tracers for changes of the physical environment.•Relationship between pesticide EFs in Calanus spp. and their changing environment.•Degraded trans-chlordane in Calanus spp. from the Atlantic water station Kongsfjorden•EF signatures in plankton appear to be driven by pelagic-benthic coupling processes. EFs of chiral pesticides are a useful scientific tool to elucidate climate change driven processes in an ice influenced Arctic food chain.