HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Khalid, R. A. Articles by Patrick, W. H. Search for Related Content PubMed Articles by Khalid, R. A. Articles by Patrick, W. H., Jr. Agricola Articles by Khalid, R. A. Articles by Patrick, W. H.

Chemical Availability of Cadmium in Mississippi River Sediment¹

ABSTRACT

There is concern that changes in the physicochemical conditions occurring during dredging and disposal of polluted sediments may increase chemical mobility and hence bioavailability of sediment-bound toxicants such as Cd. The objectives of this research were to study the chemical transformations of Cd in freshwater sediment as affected by pH and redox potential under controlled laboratory conditions and predict Cd behavior during dredging and disposal of Cd-contaminated sediments.

Mississippi River sediment suspensions were incubated at four redox potential levels (–150, +50, +250, and +500 mV) at each of three pH levels (5.0, 6.5, and 8.0) and spiked with 0.2 µCi carrier-free ¹⁰⁹Cd/g solids. Sediment suspensions were sequentially extracted for easily mobile and potentially available ¹⁰⁹Cd fractions. Essentially all of ¹⁰⁹Cd extracted from alkaline sediment suspensions was associated with potentially available chelated, insoluble organic-bound and reducible fractions and was not affected by changes in oxidation-reduction conditions. A change from alkaline to acidic pH under moderately oxidized to well-oxidized conditions resulted in ¹⁰⁹Cd transformations from potentially available organic forms to more mobile and readily available dissolved and exchangeable forms. This could create potential hazards of disposal of Cd-contaminated dredged sediments due to enhanced availability and leaching of Cd as affected by altered physicochemical environments.

Key Words: pH • redox potential • mobile Cd fraction • potentially available Cd fraction • dredged sediments

¹ Contribution of Laboratory for Wetland Soils and Sediments, Center for Wetland Resources, Louisiana State Univ., Baton Rouge, LA 70803. This study was supported by the Dredged Material Research Program of the U.S. Army Corps of Engineers, Waterways Exp. Stn., Vicksburg, MS 39180, under contract no. DACW-39-74C0076.

² Associate Professors and Boyd Professor, respectively.

Received for publication March 7, 1981.