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Speciation And Bioavailability Of Zinc In Amended Sediments
Citation:
WILLIAMS, A. G., K. G. SCHECKEL, G. Mc Dermott, D. Gratson, D. Neptune, AND JAMES A. RYAN. Speciation And Bioavailability Of Zinc In Amended Sediments. A. Gianguzza, X-d. Li, N.T. Loux (ed.), Chemical Speciation & Bioavailability. Science Reviews 2000 Ltd, London, Uk, 23(3):143-154, (2011).
Impact/Purpose:
(1) To evaluate Zn speciation in natural sediments prior to and after addition of amendments, (2) To perform biological assays to determine the toxicity and bioaccumulation of the sediment Zn prior to and after addition of amendments and (3) To link Zn speciation or the change in Zn speciation to benthic organism bioavailability based on survivability and bioaccumulation studies.
Description:
The speciation and bioavailability of zinc (Zn) in smelter-contaminated sediments was investigated as a function of phosphate (apatite) and organic amendment loading rate. Zinc species identified in preamendment sediment were zinc hydroxide-like phases, sphalerite, and zinc sorbed to an iron oxide via X-ray adsorption near edge structure (XANES) spectroscopy. Four months after adding the amendments to the contaminated sediment, hopeite, a Zn phosphate mineral, was identified indicating phosphate was binding and sequestering available Zn and Zn pore water concentrations were decreased at levels of 90% or more. Laboratory experiments indicate organic amendments exhibit a limited effect and may hinder sequestration of pore water Zn when mixed with apatite. The acute toxicity of the sediment Zn was evaluated with Hyalella azteca, and bioaccumulation of Zn with Lumbriculus variegates. The survivability of H. azteca increased as a function of phosphate (apatite) loading rate. In contaminated sediment without apatite, no specimens of H. azteca survived. The bioaccumulation of Zn in L. variegates also followed a trend of decreased bioaccumulation with increased phosphate loading in the contaminated sediment. The research supports an association between Zn speciation and bioavailability.
