TOTAL MERCURY AND METHYLMERCURY CONCENTRATION IN SEDIMENT AND SESTON OF CARTAGENA BAY, COLOMBIAN CARIBBEAN

Abstract

In Colombia, the bay of Cartagena is one of the coastal ecosystems more influenced by mercury (Hg) contamination. In order to estimate its environmental impact, in this study it was determined methylmercury (MeHg) and total mercury (HgT) in sediment and seston, taking five field samples along 2006 (February, April, June, July, and October) in five areas (Industrial zone, Dique, Center of the bay, Boca Chica, and Tierra Bomba). The mean of HgT in the sediments was 0.18 ± 0.01 μg/g dd.w., and in seston was 0.16 ± 0.002 μg/gd.w., from which about 10% was MeHg in both cases. It is reported a strong correlation between total mercury and methylmercury in both sediments (r = 0.87, p < 0.0001) and seston (r = 0.66, p = 0.0003). In Cartagena Bay, pH and redox determine the methylation process of mercury in sediments and seston as was suggested by a multiple regression analysis.