[AOS09-P11] Chemical and physical speciation of copper in the subarctic North Pacific
Keywords:copper, organic ligands, subarctic North Pacific
Concentrations of total dissolved and soluble Cu ranged from 1.28 nM – 4.82 nM, and 0.47 nM – 2.75 nM, respectively, in the subarctic North Pacific. At both CL-2 and CL-16, soluble Cu accounted for 30% - 100% of total dissolved Cu. The proportion of the soluble Cu fraction was low in surface waters, increased a maximum in the intermediate waters, and decreased slightly in deep waters. Two classes of organic ligands were detected in the surface and intermediate waters of CL-5 and CL-16, and in the intermediate waters of CL-2. In all other depths, only one class of ligand was detected. Concentrations of the stronger ligand (L1) and weaker ligand (L2) ranged from 1.02 nM – 2.95 nM, and 0.77 nM – 8.78 nM, respectively. The distributions of L1 followed closely that of total dissolved Cu in the surface waters, and no clear trend was observed in the intermediate waters. At CL-2, L1 mainly existed in the soluble phase, whereas for CL-16, soluble L1 accounted for 50% - 100% of total dissolved L1. Concentrations of L2 were relatively constant throughout the water column but elevated concentrations were detected in the surface waters of CL-5 and in the surface and intermediate waters of CL-16. On the other hand, there were a slight depletion of L2 in the intermediate waters of CL-2.