Heavy metals concentrations in zooplankton and suspended particulate matter in a southwestern Atlantic temperate estuary (Argentina)

Abstract

The present work includes part of the first studies of metals concentrations in the zooplankton from a heavily industrialized estuary of Argentina, the Bahía Blanca estuary. Cd, Cu and Pb concentrations in the zooplankton (macro and mesozooplankton) and the suspended particulate matter were measured at stations with different degree of pollution. Physicochemical variables and zooplankton composition and abundance were also analyzed. Thus, the aim of the present work was to analyze the spatial and temporal distribution of heavy metals in these two different fractions, and the possible relation among them due to their importance in the biogeochemical cycles of marine environments. Samplings were carried out during a year, from March 2005 to April 2006, every two months, at stations located near chemical and petrochemical industries, stations far from these points and one station in an intermediate location. In the mesozooplankton the mean concentrations of Cd, Cu and Pb were: 3.63±1.46, 34.46±5.40 and 11.54±3.04 µg g-1 dry weight (d.w.) respectively, while in the macrozooplankton: 3.20±2.28, 21.86±4.79 and 8.36±1.85 µg g-1 d.w. On the other hand, particulate Cd, Cu and Pb presented a mean concentration of: 3.33 ±1.22, 12.75 ±2.67 and 12.53 ±3.20 µg g-1 d.w. respectively. Metals´ levels in both the SPM and zooplankton fluctuated throughout the study time and were relatively high in the particulate phase especially for Cu and Pb. Moreover, zooplankton accumulated important concentrations of the three metals. The sources of them are probably the discharges of the industries and domestic sewages located near the estuary.