Dissolved copper, cadmium and lead in the coastal waters of Qatar, Arabian Gulf

Abstract

The concentrations of Cu, Pb and Cd have been determined in the exclusive economic zone of Qatar, Arabian Gulf during December 1993. Cathodic stripping voltammetry (CSV) was used both before and after UV destruction of organic matter in filtered samples, to differentiate between the total dissolved as well as the labile fractions. Metals distribution in the area is affected by the circulation pattern. Average total dissolved metals were 30.3 ± 13.42, 8.53 ± 4.37 and 0.61 ± 0.46 nM kg -1 for Cu, Pb and Cd, respectively. The organic fraction constituted on the average 37 ± 13 % (Cu), 28 ± 18 % (Pb) and 26 ± 12 % (Cd) of the total dissolved metal indicating the affinity of Cu > Pb > Cd to form stable organic complexes. Significant relations appeared between organic Cu with both organic carbon and chlorophyll a. Inorganic Cd/ reactive phosphorus ratio (average 1.46+0.73 nM :μ M-1) and inorganic Cu/reactive Si ratio (average 5.9 + 2.4 nM :μM -1) were three orders of magnitude higher than the global ratios indicating nutrient deficiency in this part of the Gulf.