Shi Dalin, Wang Wen-Xiong
Department of Biology, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon.
Environ Sci Technol. 2005 Dec 1;39(23):9363-9. doi: 10.1021/es051151a.
The influences of different Cd pre-exposure regimes (route, concentration, and duration of Cd exposure) on the bioavailability of Cd, Ag, Hg, and Zn to the green mussels Perna viridis were quantified in this study. Following pre-exposing the mussels to Cd, we measured the mussel's tissue Cd concentration and clearance rate, as well as the metal dietary assimilation efficiency (AE) and the influx rate from the dissolved phase of the four studied metals. Differences in the route (aqueous and dietary pathways) and the history of pre-exposure (combined Cd concentration and duration) did not significantly affect the subsequent Cd dietary and aqueous uptake. The Cd dietary AEs increased following both the dissolved and dietary Cd pre-exposure. There was a significant correlation between the Cd AE and the accumulated Cd body concentration in the mussels. Dietary assimilation of Hg and Zn also increased slightly (but not significantly) after Cd pre-exposure, but the AEs of Ag remained constant. Except for the significant decrease in the dissolved uptake of Hg, Cd pre-exposure did not apparently affect the uptake of the other three metals from the solution. Metal-metal interactions are likely to be affected by the specificity of metallothionein induction. Our study demonstrated that the Cd body concentration as well as the environmental Cd concentration instead of the history of pre-exposure was more important in affecting the Cd accumulation in the mussels. Such factors need to be considered in interpreting metal body concentrations in biomonitors.
本研究量化了不同镉预暴露方案（镉暴露的途径、浓度和持续时间）对翡翠贻贝中镉、银、汞和锌生物有效性的影响。在将贻贝预暴露于镉之后，我们测量了贻贝组织中的镉浓度和清除率，以及四种研究金属的膳食同化效率（AE）和来自溶解相的流入率。暴露途径（水相和膳食途径）和预暴露历史（镉浓度和持续时间的组合）的差异对随后的镉膳食和水相吸收没有显著影响。镉的膳食同化效率在溶解态镉和膳食镉预暴露后均有所增加。贻贝中的镉同化效率与累积的镉体浓度之间存在显著相关性。镉预暴露后，汞和锌的膳食同化也略有增加（但不显著），但银的同化效率保持不变。除了汞的溶解态吸收显著降低外，镉预暴露显然没有影响其他三种金属从溶液中的吸收。金属-金属相互作用可能受金属硫蛋白诱导特异性的影响。我们的研究表明，影响贻贝中镉积累的更重要因素是镉体浓度以及环境镉浓度，而非预暴露历史。在解释生物监测器中的金属体浓度时需要考虑这些因素。
