PARENT SESSION
67 - Metal-organic Interactions in the Environment
2:10 PM to 5:20 PM, Wednesday, 15 May 2002
Session Chair: Macalady, Donald ¹, Lipton, Joshua ², ^{1 2} .
Lehar B

(67-06) Effect of humic and fulvic acids on copper uptake by the blue mussel Mytilus edulis.

Lorenzo, JI^*,1, Mubiana, VK², Beiras, R², Blust, R, ¹ Department of Ecology and Animal Biology, Vigo, Spain, Spain² Department of Biology, Antwerp, Belgium, Belgium

ABSTRACT- The bioavailability of metals to aquatic organisms depends on their compartmentalisation and chemical speciation in the environment. It has been shown that natural organic matter has an important role in the speciation of many metals in aquatic systems, especially copper, due to its high binding constants with many organic ligands. Nevertheless few studies have focused on copper speciation and bioavailability with organic matter in seawater. More specifically, there are contrasting reports concerning the effect of natural organic matter on metal availability to marine biota. Mussels have been widely used in biomonitoring programs because they are sessile filter feeders that have a widespread distribution. To determine the effect of humic and fulvic acids on copper availability to mussels uptake experiments were conducted with excised gills and whole mussels. The speciation of Cu in the presence of humic and fulvic acids in seawater was also studied using both experimental and modelling techniques to evaluate the effect of the changes in copper speciation on copper uptake. During 1 hour experiments excised gills were exposed to copper in artificial seawater solutions containing increasing amounts of humic and fulvic acids (0-10 mg/L). A significant decrease in Cu uptake in the presence of humic and fulvic acids was observed. The effect of humic and fulvic acids on the uptake of copper by whole mussels during 24 hours exposure experiments was also studied. The results showed clear differences between the effect of humic and fulvic acids on copper uptake by excised gills and whole organisms. For example, complexation of copper by humic acid decreased copper uptake in the excised gills but increased copper uptake in the whole mussel experiments. These results demonstrate that the uptake of copper by mussels in the presence of natural organic matter does not comply with the free metal ion activity model which assumes that metal uptake from solution is function of the free metal ion activity in the environment.

Key words: copper, humic and fulvic acids, uptake, mussels