engleski

Achievement of a characterisation protocol for dissloved natural organic matter (DNOM)/metallic contaminants interactions

The study of trace metal interactions with dissolved natural organic matter (DNOM) is very difficult as in marine or coastal environment, the DNOM concentration is generally low. The goal of this study is to make an analytical protocol allowing the determination of the complexing properties of a DNOM, and especially of the marine DNOM, with metallic contaminants as copper. The challenge consists to work directly on a natural sample without using any concentration step or physico-chemical reaction which can modify the DNOM properties. This analytical protocol can give complexing parameters which can be used in chemical speciation or in contaminants transports programs, in order to predict the bioavailability of metallic cations in the environment, according to the DNOM properties. The main obstacles encountered were to work with very low, trace metal and carbon concentrations, and moreover in a marine environment. The DPASV technique used, make possible to reach the very low metal concentration needed to study the samples directly in their natural conditions. The use of a metallic titration in a logarithmic scale allow to work in a very large metal concentration range, and to determine the DNOM complexing parameters with carbon concentrations as low as those encountered in natural environment. The technique was then used on different marine and estuarine DNOM sample in order to determine their complexing properties without using any concentration step. The marine DNOM concentration is still usefull for model DNOM determination taking acount of copper, proton and calcium effect on equilibrium.

Dissolved Natural Organic Matter ; Marine environment ; Complexing properties ; Speciation ; Trace metals ; Copper ; DPASV

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