Environmental contamination and climate change in Antarctic ecosystems: an updated overview

Abiotic and biotic components of Antarctic ecosystems are valuable archives of past and current trends in global processes and play an important role in assessing emissions and long-range transport of persistent contaminants. After the ban on the production and use of alkyl-lead fuel additives, lead concentrations in Antarctic environmental matrices (snow, ice, sediments and biota) have decreased, just as the hole in the Antarctic stratospheric ozone layer is slowly shrinking following the ban on ozone-depleting gases. With the entry into force of the Stockholm Convention, the occurrence of persistent organic pollutants (POPs) in the Antarctic ecosystems could also decrease. However, the increasing anthropogenic sources of POPs in the Southern Hemisphere and the remobilization of those previously deposited in Antarctic ice could counteract the possible decreasing trend. Legacy pollutant concentrations in Antarctica are among the lowest reported in the global environment, with an exception of the bioaccumulation in various marine organisms of mercury (Hg) and cadmium (Cd) naturally occurring in Southern Ocean waters, or that of POPs in some long-lived seabirds with particular migration routes and life histories. However, despite the protection guidelines, long-range transport processes and especially the increase in human activities in Antarctica are sources of many persistent contaminants not yet subject to regulatory criteria and often lacking standardized sampling and analytical procedures. Chronic exposure to anthropogenic contaminants (legacy and of emerging interest) and pathogenic microorganisms near coastal scientific stations could cause synergistic or additive effects on marine biota. Most Antarctic marine organisms are endemic, with unique ecophysiological adaptations, and are also exposed to climate-related stressors. Warming and acidification of Southern Ocean waters along with increased melting of ice will likely affect the transport, pathways and environmental fate of persistent contaminants and could interfere with the metabolic processes of Antarctic organisms involved in the uptake and detoxification of environmental contaminants. Therefore, to implement environmental protection protocols around the coastal stations, the Council of Managers of National Antarctic Programs should evaluate the possible cumulative impact on biotic communities in the context of changing climatic and environmental conditions.