Organic pollutants and their correlation with stable isotopes in vegetation from King George Island, Antarctica.

Vegetation samples from King George Island, Antarctica (62°05'S, 058°23'W) were collected in the austral summer of 2004-2005. Lichens (Usnea aurantiaco-atra and Usnea antarctica), mosses (Sanionia uncinata, Syntrichia princeps and Brachytecium sp.), and one angiosperm (Colobanthus quitensis) species were analyzed for persistent organic pollutants as well as δ(13)C and δ(15)N stable isotopes. The following contaminants were found above the method detection limit (MDL): HCB (0.141-1.06 ng g(-1) dry weight), HCHs (<MDL to 1.20 ng g(-1) dw), DDTs (<MDL to 1.73 ng g(-1) dw), PCBs (7.76-18.6 ng g(-1) dw) and PBDEs (0.146-0.811 ng g(-1) dw). In all cases, levels in mosses were higher than in lichens (one order of magnitude higher for OCs), suggesting that specific biogeochemical processes were involved in the transport, exposure and absorption for each group. Carbon stable isotope ratios showed clearly different ranges for lichens (δ13C from -21.13‰ up to -18.43‰) and mosses (-25.99‰ to -21.64‰). The only angiosperm species investigated exhibited 13C signature within the moss range. A large range of δ15N was found (-7.67‰ to 20.75‰) and seemed to be related to nitrogen uptake from different animal-derived sources. Pearson's correlation showed significant results for some contaminants (e.g. HCHs/HCB and PCBs/DDTs) and suggested the influence of the origin of both nitrogen and pollutants, notably taking secondary sources (animal excrements/remains, for instance) into consideration.