European Salt Marsh Modelling - EUROSAM

TASK 8 - MODELLING THE BIOGEOCHEMICAL PROCESSING OF ARSENIC BY SALT MARSHES

Final Report  July 2000

Abstract (Main Findings)

 

Models were developed and simulations accomplished for Arsenic transport and distribution in the Tagus, including dissolved forms, suspended and settled sediment.

A new version of LC-ESI-MS/MS for Arsenic speciation was developed as well an HPLC-MW-HG-QF-AAS technique.

The terms of exchange of estuarine water with the salt marsh observed, show different RefAs for ebb and flood waters.

Refractory arsenic (RefAs), mainly near the surface, seems to be relatively important in interstitial waters and represent a non negligible As fraction (32%) and concentration.

An emmision of AsH3 equivalent to 1.35 ng in 400 cm3 or 43.1 ngAs/day/m2, was measured from sediment incubation experiments.

Arsenic concentrations are much higher in Crustacea (Palaemonetes sp.) than in fish (Liza sp.) and these show an almost perfect linear decrease of arsenic content with length. The level of arsenic in Epiphytic algae seems to be significantly higher than in the aereal part of the neighbour salt marsh angiosperms.