Impacts de l'activite humaine en milieu cotier des hautes latitudes: Exemple de la station Jubany, Antarctique.

摘要

We carried out an analysis about the presence of main toxic compounds previously reported as relevant Antarctic contaminants such as polycyclic aromatic hydrocarbons (PAHs), heavy metals, butyltin compounds and polychlorinated biphenyls (PCB). Jubany station (Argentina), the terrestrial area around it and the Potter Cove basin were selected as the study area.;The suspended particulate matter (SPM) in seawater showed no detectable levels of PAHs, with exception of an area close to the boats wharf where the pattern of PAHs evidenced the influence of recent fuel spills. Biota associated to the cove evidenced PAH concentrations in accordance with their environment. However, the liver tissue from Notothenia coriiceps turned to be enriched in 7, I2-dimethylbenz(a)anthracene. The presence of this known carcinogenic compound, which was only detected as traces in the environment, represents a relevant point and its hepatic concentration as well as its correlation with hepatic damage in Antarctic fishes should be investigated in the future.;The presence of the antifouling compound tributyltin (TBT) and/or their derivatives mono and dibutylated tins was detected heterogeneously either in sediment samples or in the associated marine organisms. Although measured levels were low, 2 of 9 sampled sites showed detectable concentrations of TBT. These sites are located in the area where the ice breakers and other polar vessels operate or are searching for refuge during strong Antarctic storms. In this situation the abrasion produced by the floating ice pieces could cause a detaching of paint particles which rapidly sediment and accumulate in the basin of the cove causing the observed heterogeneous distribution.;The presence of different PCB congeners cannot be detected, neither in sediments samples nor in tissue samples from the biota associated to the cove. Although previous works reported the presence of detectable levels of PCB in the Antarctica which was attributed to the global transport, the presence of such a phenomenon can not be confirmed for the studied area.;Analysis of PAHs in soil and sediment during two consecutive years showed that Jubany station has a low level of contamination with these compounds. The results revealed that the upper layer of the permafrost acts as a barrier for downward PAHs migration. In addition, PAH concentrations in soils from the two sampling programs showed a decrease by one order of magnitude in 2005 compared with values obtained in 2004. Such a decrease was accompanied by a concomitant increase of PAH concentrations in coastal marine sediment (mainly in sampling sites 1 and 2 located in the inner part of the cove) and also correlated with an unusual high precipitation regime, suggesting that an important washout of soil PAH occurred during the lime interval between samplings.;Finally, the analysis of 7 different heavy metals (Fe, Zn, Cu, Mn, Cd, Pb and Cr) showed that, in a general view, concentrations are mainly affected by the geochemical characteristics of the area, the anthropogenic influence being negligible. In sediment samples, as previously mentioned for PAHs, sampling sites I and 2 showed significantly higher concentrations of lead (Pb) that would be related to the human activity at Jubany station.;In conclusion, this work showed that the levels of anthropogenic contamination affecting the surroundings of Jubany station are low and do not represent any significant environmental risk. However, several relevant points that emerge from this study must be noted: (I) the oceanographic characteristics of the studied area are a determinant factor for the contaminants distribution. (II) The permafrost layer proves to be a relevant barrier to the downward migration of certain contaminants, which tend to accumulate in the first cm of the permafrost table. (III) This spatial distribution of contaminants in soils could be deeply affected by the local effects of the global warming, which could move a significant amount of organic contaminants, initially retained in the permafrost, to the coastal marine environment with adverse and unpredictable ecological consequences. (IV) The local geochemical characteristics represent the main factor determining the concentration of analyzed heavy metals. (V) A number of activities related to the operation of Jubany station are responsible of the detectable levels of some of the studied contaminants. (Abstract shortened by UMI.).