Copper complexation during spring phytoplankton blooms in coastal waters

Publisher Website
Google Scholar
Abstract
Cupric ion bioassays were conducted throughout the spring phytoplankton bloom season at 2 stations; one estuarine, dominated by dinoflagellates, the other coastal, dominated by diatoms. Cu-complexing ligands were detected at both locations throughout this period. Ligand concentrations varied between 0.1-0.75 .mu.M, with the estuarine concentrations typically 2-4 times higher than costal values. Ligands from both locations were destroyed by UV-oxidation and had similar conditional stability constants (range 108.3-109.2) that were significantly correlated with pH, suggesting that the complexing materials are organic chelators with weak acid functional groups. All measured or calculated parameters (DOC [dissolved organic C] ligand concentration, total Cu concentration, salinity and pH) remained relatively constant at the coastal station through time. The estuarine station was more dynamic, with DOC, total Cu and ligand concentrations varying 2-4 fold during the study. Although ligand concentrations were significantly different between the 2 locations, concomitant fluctuations in total dissolved Cu and conditional stability constants resulted in a relatively constant estimate of the maximum free cupric ion activity at both stations (near 10-11 M). Cu toxicity alone was not responsible for the distinctly different estuarine and nearshore phytoplankton assemblages, although sensitive species might have been inhibited at both locations. Major phytoplankton blooms at both sites were not accompanied by changes in DOC or complexation capacity. A significant inverse correlation between ligand concentration and salinity suggests a terrestrial or sedimentary origin for the Cu-complexing compounds.

This publication has 2 references indexed in Scilit: