Dissolved copper speciation behaviour during estuarine mixing in the San Simon Inlet (wet season, Galicia). Influence of particulate matter

The speciation trend of dissolved copper (DCu) was studied for the first time in a Galician Ria across the estuarine zone of the Vigo Ria during the wet season and related to the copper levels in suspended particulate matter (PCu) and sediments. In the riverine and ocean endmembers DCu concentrations can be defined as pristine (<4 nM in Oitaven River). DCu is not conservative during the estuarine mixing and its concentration increase (5e8 nM) cannot be only associated to PCu (0.5e1.0 nM) variations and the ria sediments may be an important DCu source. DCu speciation was mainly controlled by two types of ligands (log K0 L1¼12:9e13:9; and log K0L 2¼10:8e12:1). In all samples the concentration of L1 (CL1¼15e34 nM) was greater than that of copper, which speciation is so dominated by this strong organic ligand. The transport of copper contamination from the middle Ria to the San Simon Inlet is limited during the wet season; in spite of similar salinities, DCu in the inlet (6 nM) was much lower than at Rande Strait (15 nM).