ITN TRA-ANNUAL VARIATIONS OF Cd AND Pb ITN WATER FROM A SUBTROPICAL COASTAL LAGOON, GULF OF MEXICO

Abstract

This study evaluated intra-annual variations of Cd and Pb concentrations in water from two sites in the central portion of a subtropical coastal lagoon (Laguna Madre) from the Gulf of Mexico. Sites were located at a different distance from the primary river discharge into the lagoon (site 1 at 10 km and site 2 at 30 km). The overall mean Ph concentrations found in the water were 0.37 mg/l and 0.42 mg/l for sites 1 and 2, respectively, whereas Cd levels were 0.04 mg/I for both sites. Significant intra-annual variations (p <0.05) in metal concentrations were only detected for Pb, which showed very similar seasonal variations for both sites. However, no similar seasonal patterns were observed during both study periods, lntra-annual variations in Pb levels could be related to seasonal differences in the entrance of this metal into the lagoon via runoffs and river discharges.