Ornithogenic mercury input to soils of Admiralty Bay, King George Island, Antarctica

While long-range transport is believed to be the primary source of mercury (Hg) in Antarctica, it is known that seabirds transport organic matter, nutrients, and contaminants from the sea to land. However, these biologically mediated inputs have not been widely evaluated. Anthropogenic contamination and natural occurrence have increased Hg in the environment. Antarctic seabirds, such as penguins and shags, form dense colonies and may provide an important local source of Hg input. This study determined the concentrations of total mercury (THg) in ornithogenic soils associated with eight species of seabirds on King George Island (Antarctica Peninsula) and evaluated species-specific differences. Soils from colonies of Southern Giant Petrel (Macronectes giganteus; mean ± SD, 213 ± 132 ng g−1) and Imperial Shag (Leucocarbo atriceps; 144 ± 54 ng g−1) had significantly higher THg concentrations than non-ornithogenically influenced (29 ± 35 ng g−1) soil samples. Soils associated with Southern Giant Petrels also had significantly higher THg than those of Kelp Gull (Larus dominicanus; mean 17 ± 15 ng g−1), which we speculate is a result of petrels occupying a higher trophic position in the marine food web, which leads to a greater accumulation of Hg in their organism, then being excreted through guano. Moreover, a moderate relationship observed between THg-Cd and THg-SOM suggests an influence of those species. Our data confirm that Antarctic seabird colonies are associated with higher soil THg concentrations and report the higher concentration for ornithogenically influenced soil (508 ng g−1) in a level similar to an anthropogenic site and highlight the need for a more thorough evaluation.

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