溶解性有机碳影响铜对背角无齿蚌稚蚌的急性毒性研究

为了探究溶解性有机碳(DOC)影响铜对背角无齿蚌稚蚌的急性毒性,以0.1‰盐浓度的去离子水为实验用水,设定梯度为0、10、23、45、90和180μg·L-1的Cu浓度,再分别添加0.3、0.8、1.5、3.0和6.0 mg C·L-1DOC形成实验溶液,开展了96 h铜暴露下背角无齿蚌1~2 d稚蚌的急性毒性实验。对应于各DOC浓度组的96 h-Cu-EC50值分别为19(95%置信区间:13~27,下同),23(17~31),17(12~23),13(8~19)和10(5~14)μg·L-1;DOC浓度与稚蚌的96 h-Cu-EC50值的变化呈负相关关系(R=-0.968,P=0.007)。本研究的结果显示,背角无齿蚌稚蚌对环境中Cu浓度的变化十分敏感,96 h-Cu-EC50值与国家渔业水质标准(GB11607—89)Cu的限量值十分接近,适于预警水环境中Cu的污染水平;但仅调整DOC浓度这一个水化学指标对降低铜毒性、减少稚蚌的死亡等方面效果并不明显。

Influence of Dissolved Organic Carbon on Acute Toxicity of Copper to Newly-transformed Juveniles of the Chinese Pond Mussel Anodonta woodiana

In order to investigate the influence of dissolved organic carbon (DOC) on copper (Cu) toxicity to "standardized" Anodonta woodiana,the unique bioindicator of "Freshwater Mussel Watch" project,acute 96 h Cu toxicity tests were performed.This was done with newly-transformed juvenile mussels (age:1-2 d) of A.woodiana at five nominal DOC concentrations (0.3,0.8,1.5,3 and 6 mg·L-1 as carbon C]) in experimental waters with Cu concentrations of 0,10,23,45,90 and 180 μg·L-1 in deionized water and adjusted simultaneously to a salinity of 0.1‰.Median effective concentrations (EC50s) for Cu were 19 (95％ confidence:13～27,similarly hereinafter),23 (17～31),17 (12～23),13 (8～19) and 10 (5～14) μg·L-1 in the five DOC concentration groups,respectively.In addition,EC50s were negatively correlated with DOC concentrations (R =-0.968) and the EC50s significantly decreased with this water chemistry parameter (P＜0.007) in the A.woodiana groups.The results of this study suggest that the newly-transformed juveniles of A.woodiana are vulnerable to Cu contamination at concentrations close to the permissible limit for Cu as outlined in the National Water Quality Standard for Fisheries (Standard Code:GB11607-89) of China and will be suitable as early-warning indicators for Cu pollution levels.Nevertheless,DOC alone would not be protective against metal toxicity under the test conditions of the present study.