BIOAVAILABLE AND TOTAL COPPER AND LEAD IN TERRIGENOUS SEDIMENTS IN THE INNER CONTINENTAL SHELF OFF VERACRUZ, SOUTHERN GULF OF MEXICO

Abstract

The inner continental shelf adjacent to the city and port of Veracruz (ICSV) in the southern Gulf of Mexico, which is influenced by the Jamapa River, has been considered to be polluted. Moderate to high Cu and Pb concentrations have previously been reported in the shelf’s terrigenous sediments. These elements are derived from deposition of materials from mainland sources via river transport and may threaten marine life in the coastal area. Because Cu and Pb bioavailability has not been previously assessed in the region, the aim of this study was to determine (i) bioavailability and total concentrations of these elements in the terrigenous sediments of the ICSV, (ii) if concentrations of these elements in sediments are associated with distances from primary sources, and (iii) if concentrations differ during dry and rainy seasons. Bioavailable general average concentrations were 0.21 µg/g for Cu, and 0.24 µg/g for Pb, which accounted for 4.4-4.9 % of the total content. The bioavailable concentrations were higher during the rainy season, and in the fluvial plume of the Jamapa River. The total content of Cu and Pb was significantly associated with fine sediments and exhibited high concentrations in the new port facilities area. Hence, it is concluded that the Jamapa River is a primary source of trace metals to the ICSV. Finally, as concentrations of trace metals are lower than previous records for sediments in the southern Gulf of Mexico and lower than background levels and maximum permissible limits, the ICSV is presently not contaminated by Cu or Pb.