溶解性有机碳影响铜对背角无齿蚌稚蚌的急性毒性研究

摘要

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180 μg· L-1的Cu浓度,再分别添加03、0.8、1.5、3.0和6.0 mg C·L-1 DOC形成实验溶液,开展了96 h铜暴露下背角无齿蚌1～2d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.%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.