Conference Proceeding

Metal Re-distribution and Bioavailability Enhancement in River Sediment after In-situ Ca(NO3)2 and CaO2 Treatments.

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Contaminated river sediment has been subject to urban, industrial, agricultural and various anthropogenic discharges. High concentration of nutrients and organic chemicals are often found in the sediment. The contaminated sediment can be treated by different physiochemical exsitu remediation methods. However, the treated sediment may still be disposed of at landfills if the contamination level of the sediment does not fulfill stringent standards for recycle purposes. On the contrary, in-situ biogeochemical remediation is considered a waste-free treatment method with less disruption to the ecosystem. Yet, it has been reported that in-situ sediment remediation mobilized metals from sediment and may enhance the toxicity upon aquatic life. In such regard, contaminated river sediment was treated in this study by the addition of Ca(NO3)2 or CaO2 as to mimic the in-situ odor mitigation, and acid volatile sulfide (AVS) and organic pollutant removal. The effect of Ca(NO3)2 or CaO2 on the bioavailability, bioaccessibility, and redistribution of metals in sediment was evaluated. After applying Ca(NO3)2 or CaO2, the metal concentrations in the sediments reduced insignificantly. However, as indicated by the assessments of [SEMtot- AVS]/fOC (SEM and fOC refer to simultaneously extracted metals and the fraction of organic carbon in sediment, respectively) and the bovine serum albumin leaching test, both bioavailability and bioaccessibility of metals (Cu, Zn, and Ni) to benthic organisms were enhanced after 35 days of remediation. Metal redistribution from relatively stable fractions (oxidizable and residual fractions) to weakly bound fractions (exchangeable and reducible fractions) was found in Ca(NO3)2- and CaO2-treated sediments, and corresponded well with the results of enhanced metal bioavailability. Upon purposeful assessment and investigation, this study provides scientific findings for determining the appropriate strategy for in situ sediment remediation.

Published: 01 August 2017

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Copyright: © 2017 CHUA Hong. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.