SS4.02 The Role of Microbiology in Trace Metal and Organic Contaminant Cycling in Aquatic Systems
Date: Wednesday, June 12, 2002
Location: Poster Session - VCC
 
De GieterM, Vrije Universiteit Brussels, Analytical and Environmental Chemistry, Brussels, Belgium, mdgieter@vub.ac.be
De Galan, S, , Vrije Universiteit Brussels, Analytical and Environmental Chemistry, Brussels, Belgium, sdegalan@vub.ac.be
Baeyens, W, , Vrije Universiteit Brussels, Analytical and Environmental Chemistry, Brussels, Belgium, wbaeyens@vub.ac.be
 
BIOGEOCHEMICAL PROPERTIES OF AS IN THE SCHELDT, BELGIUM
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The Scheldt watershed is heavily polluted by inputs of industrial and domestic wastes. The Scheldt estuary is Belgiumís main land drainage canal to the coastal waters. On several occasions, total dissolved and total particulate As were measured, and additionally on some cruises, speciation studies on the dissolved phase were carried out. In the estuary, longitudinal profiles of dissolved As have a convex shape, reflecting the influence of redox, desorption and complexation processes. Maximum dissolved concentrations were found in summer, as a result of biological activity. Although As(III) is thermodynamically unstable, this form was present in appreciable amounts, even up to 70% of the total. In the Zenne, a tributary of the Scheldt, these high As(III) fractions coincided with a depletion in dissolved oxygen. Longitudinal profiles of particulate As show an inverse linear trend, decreasing from the fresh water end-member to the mouth. This kind of profile suggests a strong domination by dilution. Relationships between As concentrations and a number of parameters such as Fe, Mn, phosphate, chlorophyll-a and oxygen were established.