ARSENIC SPECIATION IN MARINE-SEDIMENTS - EFFECTS OF REDOX POTENTIAL AND REDUCING CONDITIONS

The speciation of arsenic in the environment is among others controlle d by reduction, methylation and oxidation processes and therefore infl uenced by the prevailing redox conditions. In this study we have analy zed sediments taken from La Coruna estuary in the north west of Spain. Inorganic (trivalent and pentavalent) and the organic (MMA and DMA) a rsenic speciation is related to Eh, Fe and Mn load. The variation of t he arsenic species concentration and other parameters was analyzed at different depths in some of the sampling points. Low arsenic concentra tions (1-10 mu g.g(-1)) were found. In spite of oxidising conditions ( Eh values between 31-96 mV), most of the samples showed a higher As(V) percentage than As(III). Principal component analysis was made to see sample groups and the results showed that speciation depends on reduc ing conditions (Eh and Mn).