LACK OF CORRELATION BETWEEN MERCURY IN SEDIMENTS AND FISH MUSCLE, LAKE CHAPALA MEXICO

The aim of this study was to evaluate the relation between mercury concentrations in wild cups and sediments at the same points from Lake Chapala, Mexico. Total mercury (HgT) concentration were analyzed in the edible part of 142 carps (Cyprinus carpio), in 14 sediments and in water sites where the fish were caught. Correlation test between HgT from fish muscle and HgT sediments in each site were evaluated. Graphic representation of global trend of HgT in fish flesh into Lake Chapala is shown. The overall mean HgT in edible muscle of carp was 0.39 mg kg(-1), below the Mexican and International mercury limits for fish flesh. HgT in sediments were higher than reported from sediments in USA and Canada. The correlation coefficient test (r) between sediment and fish HgT concentration was 0.394. Two Lake Chapala areas were detected with significant high HgT in sediments but La Palma point at soutest close to Lerma River mouth was positive correlated with high fish HgT concentration. The pH of the Lake Chapala water (8.1-9.5) was maybe the key factor that influences the low concentration of HgT in water, and therefore in HgT carp concentration.