海水中镉对牙鲆的生物有效性研究

采用暴露实验方法，研究了海水中镉在牙鲆内脏、肌肉、鳃组织内蓄积及在清洁海水中排放规律，以及海水中总有机碳（TOC）浓度对镉吸收的影响.结果表明，镉暴露浓度为0.5 mg·L^-1时，牙鲆各组织镉蓄积量随暴露时间增加而增大，第10天达吸收平衡，Cd蓄积量顺序为内脏（147.73 mg·kg^-1）>鳃（15.55 mg·kg^-1）>肌肉（4.578 mg·kg^-1），表明内脏是重金属镉蓄积的主要部位.染毒13 d后,将牙鲆移入清洁海水中,结果表明，随排放时间增加,各组织镉蓄积量明显下降，排放至第15天时各组织镉排出率为内脏团（80.66%）>鳃（73.66%）>肌肉（56.84%），表明受镉污染牙鲆经清洁海水排放后,有望达到食用标准.海水中TOC浓度对镉蓄积量有明显影响.随着TOC浓度升高，各组织内镉蓄积量明显下降，表明海水TOC能降低镉的生物有效性.

Bioavailability of cadmium in seawater to Paralichthys olivaceus

With exposure experiment, this paper studied the accumulation and elimination of cadmium (Cd) in the viscera, muscle and gill of Paralichthys olivaceus, and the effects of TOC concentration in seawater on the Cd accumulation. The results showed that when the exposure concentration of Cd was 0.5 mg x L(-1), its accumulation in test tissues increased with time, and reached equilibrium on the 10th day. The accumulation was in order of viscera (147.73 mg x kg(-1) DW) > gill (15.55 mg x kg(-1) DW) > muscle (4.578 mg x kg(-1) DW), which meant that viscera was the main place for Cd accumulation. Determinations after moving the fish into clear seawater on the 13th day of exposure showed that due to depuration, the Cd accumulation in test tissues decreased with time. On the 15th day after moving, the Cd elimination was in order of viscera (80.66%) > gill (73.66%) > muscle (56.84%), suggesting that the Cd accumulation in Paralichthys olivaceus could be reduced to meet safe food standard. The TOC concentration in seawater had a significant effect on Cd accumulation, i.e., the accumulation of Cd decreased significantly with increasing TOC concentration, demonstrating that the TOC in seawater could decrease the bioavailability of cadmium.