Geochemistry of Cd, Cr, and Zn in Highly Contaminated Sediments and Its Influences on Assimilation by Marine Bivalves

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• 作者：Wenhong Fan ; Wen-Xiong Wang ; and Jingsheng Chen
• 刊名：Environmental Science & Technology
• 出版年：2002
• 出版时间：December 1, 2002
• 年：2002
• 卷：36
• 期：23
• 页码：5164 - 5171
• 全文大小：139K
• 年卷期：v.36,no.23(December 1, 2002)
• ISSN：1520-5851

文摘

We tested the controls of metal geochemistry in sedimentscollected from an extremely contaminated Chinese bayon metal assimilation by marine mussels and clams.Metal speciation in the contaminated sediments, quantifiedby the Tessier operational extraction method, wassignificantly dependent on metal concentrations in thesediments. The fractions of Cd in the easily exchangeableand carbonate phases increased, while the reducibleand residue phases decreased with increasing Cdconcentration. The majority (72-91%) of Cr was associatedwith the residue component, with the remainder of Cr inthe organic matter and reducible phases. Zn in carbonatephase increased, whereas in the organic matter andresidue phases it decreased with increasing Zn concentration.The bioavailability of Cd, Cr, and Zn to marine greenmussels (Perna viridis) and clams (Ruditapes philippinarum)was quantified using radiotracer spiked technique withconcurrent measurements of speciation of spiked metals.There was a significant correlation between the Cdassimilation efficiency (AE) by both mussels and clamsand Cd partitioning in the easily exchangeable and reduciblephases. In contrast to previous studies, a negativecorrelation was found between the Cd AE and its totalconcentration in sediment, likely caused by the saturationof Cd binding sites in the gut or by its antagonisticinteraction with a very high Zn concentration in thesecollected sediments. In contrast, there was no significantcorrelation between the AEs of Cr or Zn and any oftheir geochemical phases or their concentrations. Themetal AEs were further quantified by experimentallymanipulating different concentrations and ratios of acidvolatile sulfide (AVS) and simultaneously extractable metals(SEM). There was no statistically significant relationshipbetween the AEs of the three metals and the concentrationsof AVS and SEM or [SEM-AVS]. Geochemical controlson metal assimilation from contaminated sediment aretherefore only relatively apparent for Cd. The influences ofmetal speciation on metal bioavailability can be confoundedby the degree to which sediments are contaminated withmetals.