厚壳贻贝中铬的形态特征及六价铬的转化规律

Morphological characteristics of chromium and transformation of hexavalent chromium in Mytilus coruscus

以厚壳贻贝为研究对象,采用六价铬[Cr(Ⅵ)]标准物质为染毒试剂,比较同一形态Cr在厚壳贻贝体内的含量变化,并监测不同时间节点Cr的形态变化,探讨Cr(Ⅵ)在厚壳贻贝中的转化规律。结果表明:Cr在厚壳贻贝体内主要以三价铬[Cr(Ⅲ)]和有机Cr形态存在,其中Cr(Ⅲ)占21.0%~29.9%,有机Cr占70.1%~79.0%;Cr(Ⅵ)无法稳定存在于厚壳贻贝体内。暴露实验中,厚壳贻贝体内蓄积的Cr(Ⅵ)都被转化成Cr(Ⅲ)和有机Cr,使得厚壳贻贝体内的总Cr、Cr(Ⅲ)和有机Cr含量均显著提升;随着厚壳贻贝体内Cr含量的增加,总Cr、Cr(Ⅲ)和有机Cr的转化率逐渐降低,Cr含量增速也逐渐放缓。待厚壳贻贝中Cr趋于富集平衡状态时,Cr含量增长接近停滞,总Cr、Cr(Ⅲ)和有机Cr的转化率大幅下降,其中,有机Cr部分转化为Cr(Ⅲ),使Cr(Ⅲ)比例持续升高。

Taking Mytilus coruscus as the research object and using hexavalent chromium[Cr(Ⅵ)]standard substance as the poisoning reagent,the content of chromium(Cr)in M.coruscus with the same speciation was compared,and the speciation of Cr at different time nodes was monitored,and the transformation of Cr(Ⅵ)in M.coruscus was discussed.The results showed that the trivalent chromium[Cr(Ⅲ)]and organic Cr were confirmed as the two main states of Cr in M.coruscus by using Cr(Ⅵ)standard substance as the poisoning reagent,with percentages of 21.0%-29.9%for Cr(Ⅲ),and 70.1%-79.0%for organic Cr.Cr(Ⅵ)could not be stable in M.coruscus.In the exposure experiment,accumulation of Cr(Ⅵ)in M.coruscus in vivo was converted into Cr(Ⅲ)and organic Cr,resulting in the contents of total Cr,Cr(Ⅲ)and organic Cr increased significantly.With the increase of Cr content in M.coruscus,the conversion rate of total Cr,Cr(Ⅲ)and organic Cr decreased gradually,as well as the content growth rate.When the enrichment tended to equilibrium,the Cr content increased nearly stagnation,and the conversion rates of total Cr,Cr(Ⅲ)and organic Cr decreased significantly,and the proportion of organic Cr to Cr(Ⅲ)continued to increase.