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Metal associations in anoxic sediments and changes following upland disposal
Citation Link: https://doi.org/10.15480/882.430
Publikationstyp
Journal Article
Date Issued
1986
Sprache
English
Author(s)
TORE-DOI
Volume
12
Issue
3-4
Start Page
313
End Page
321
Citation
Toxicological and environmental chemistry 12 (1986), 313-321
Publisher DOI
Publisher
Taylor & Francis
[Presented 20th January 1986 at the 2nd IAEAC Workshop on Carcinogenic and/or Mutagenic Metal Compounds, CH-1884 Villars-sur-Ollon]
The ecological effects of heavy metals in contaminated sediments are more determinded by the chemical form and reactivity than by the level of accumulation. Dredging of anoxic sediments and disposal on land is attended by changes of redox conditions. Under oxidizing conditions some controlling solid compounds may change gradually thus changing the solubility of certain metals.
Chemical extraction experiments for estimating characteristic association forms of heavy metals in anoxic sediments were carried out, both under presence and absence of air during the analytical procedure. Drying of the sediment decreases the proportion of the sulfidic metal fractions to a stronger degree, and oxidized Cd and Zn are found in the most available, exchangeable fraction.
With respect to long-term effects acidification of poorly buffered sludges after disposal on land is probably the most important factor affecting metal associations and mobility. For many metal examples a linear relationship has been found between decreasing pH values and increasing dissolved metal concentrations. To quantify these relationships and for better comparison of samples a simple test procedure is proposed which is bases on pH differences before and after addition of acid.
The ecological effects of heavy metals in contaminated sediments are more determinded by the chemical form and reactivity than by the level of accumulation. Dredging of anoxic sediments and disposal on land is attended by changes of redox conditions. Under oxidizing conditions some controlling solid compounds may change gradually thus changing the solubility of certain metals.
Chemical extraction experiments for estimating characteristic association forms of heavy metals in anoxic sediments were carried out, both under presence and absence of air during the analytical procedure. Drying of the sediment decreases the proportion of the sulfidic metal fractions to a stronger degree, and oxidized Cd and Zn are found in the most available, exchangeable fraction.
With respect to long-term effects acidification of poorly buffered sludges after disposal on land is probably the most important factor affecting metal associations and mobility. For many metal examples a linear relationship has been found between decreasing pH values and increasing dissolved metal concentrations. To quantify these relationships and for better comparison of samples a simple test procedure is proposed which is bases on pH differences before and after addition of acid.
Subjects
Sediment
sludges
pH effects
redox effects
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