Copper and mercury complexing capacity of organic matter from a mangrove mud flat environment, Sepetiba Bay, Brazil
Résumé
The biochem. of trace metals in mangrove environments has raised special attention due to the potential role of sediments in mangrove as both a sources and sinks for these pollutants. In the present study, we investigate the complexing capacity of org. matter in pore tidal waters, for two contrasting metals Cu and Hg, for which mangrove have been reported as a sink and source, resp. We hypothesize that post depositional changes in the org. matter are responsible for the different complexing capacities of org. matter, which results in a different migration pattern between Hg and Cu and in layer accumulation of Cu relative to Hg in mangrove environments. By using complexing capacity methods, some evidence was shown of different mechanisms of transport for Cu and Hg in mangrove systems. Org. matter from the mud flat surface is more able to transport Cu ions than the deep sediment surface, and inversely for Hg.