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Chemical Availability of Cadmium in Mississippi River Sediment
Author(s) -
Khalid Rashid A.,
Gambrell Robert P.,
Patrick William H.
Publication year - 1981
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq1981.00472425001000040021x
Subject(s) - dredging , sediment , cadmium , environmental chemistry , leaching (pedology) , redox , chemistry , bioavailability , contamination , environmental science , geology , inorganic chemistry , soil water , soil science , ecology , oceanography , biology , organic chemistry , paleontology , bioinformatics
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 µ Ci carrier‐free 109 Cd/g solids. Sediment suspensions were sequentially extracted for easily mobile and potentially available 109 Cd fractions. Essentially all of 109 Cd 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 109 Cd 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.