Spatial and temporal distribution of cadmium and copper in water and zooplankton in the Bahía Blanca Estuary, Argentina

FERNANDEZ SEVERINI, M.; BOTTÉ, S.E.; HOFFMEYER, M.; MARCOVECCHIO, J.E.

ESTUARINE COASTAL AND SHELF SCIENCE

ACADEMIC PRESS LTD-ELSEVIER SCIENCE LTD

Lugar: UK; Año: 2009 vol. 85 p. 57 - 66

0272-7714

Cadmium and copper in the dissolved and particulate phase and in zooplankton were determined in the Bahía Blanca estuary during six surveys from March to December 2005. Temperature, pH, salinity, dissolved oxygen, suspended particulate matter, particulate organic matter and chlorophyll-a were also considered. Dissolved Cd was below the detection limit (0.2 µg L-1) for almost the entire study period whereas Cu concentrations (0.5-2.4 µg L-1) indicated a continuous dissolved Cu input. Particulate Cd concentrations ranged from below the detection limit (<0.01) to 28.6 µg g-1 d.w. and high concentrations were linked to the urban effluents and dredging activities. Particulate Cu ranged from below the detection limit (<0.04) to 53.5 µg g-1 d.w. Cd in mesozooplankton ranged from below the detection limit (<0.01) to 37.4 µg g-1 d.w. Some of the Cd levels were higher than those reported for other aquatic ecosystems. Cu in the mesozooplankton ranged from 1.3 to 89.3 µg g-1 d.w., values which were within the reported values or higher than other studies. The logs of the partition coefficients (log (Kd)) of Cd ranged from 0.60 to 3.95, while log (Kd) for Cu ranged from -0.39 to 2.79. These values are lower than both those calculated for other estuaries and the typical coefficients for marine environments. Bioconcentration factors (log BCF) of Cd ranged from 0.04 to 4.18, indicating that Cd concentration is higher in zooplankton than in the dissolved phase. Log BCF of Cu ranged from -0.39 to 3.25. The negative value indicates that Cu concentration is higher in the dissolved phase, while the positive values reveal bioconcentration. The logs of the biomagnification factors (log BMF) of Cd were low, with a range between -3.45 and 2.21. Positive values indicate biomagnification while negative values indicate biodiminution. In general, no significant dissolved Cd concentration appeared to be present in the Bahía Blanca estuary and Cd values did not indicate a critical environmental status. The particulate phase is the major carrier for Cd and Cu and TPCd concentrations indicated an important Cd input while TPCu values were within the normal values for an anthropogenically stressed estuary but not for a strongly polluted system. This fraction was the most important metal source for the mesozooplankton. Moreover, the highest metal concentrations were present in the mesozooplankton since most of the bioconcentrations and biomagnifications factors were positive.