Chen Wen-Qian, Wang Wen-Xiong, Tan Qiao-Guo
Key Laboratory of the Coastal and Wetland Ecosystems of Ministry of Education, College of the Environment and Ecology, Xiamen University, Xiamen, Fujian 361102, China.
Key Laboratory of the Coastal and Wetland Ecosystems of Ministry of Education, College of the Environment and Ecology, Xiamen University, Xiamen, Fujian 361102, China; Center for Marine Environmental Chemistry and Toxicology, Xiamen University, Xiamen, Fujian 361102, China; Division of Life Science, The Hong Kong University of Science and Technology, Clearwater Bay, Kowloon, Hong Kong.
Environ Pollut. 2017 Mar;222:323-330. doi: 10.1016/j.envpol.2016.12.033. Epub 2016 Dec 24.
The effects of salinity on metal toxicity are complex: not only affecting metal bioaccumulation, but also altering the physiology and sensitivity of organisms. In this study, we used a toxicokinetic-toxicodynamic (TK-TD) model to separate and quantify the dual effects of salinity on copper (Cu) toxicity in a euryhaline clam Potamocorbula laevis. The toxicokinetics of Cu was determined using the stable isotope Cu as a tracer at concentrations (10-500 μg L) realistic to contaminated environments and at salinities ranging from 5 to 30. At low Cu concentrations (ca. 10 μg L), Cu bioaccumulation decreased monotonically with salinity, and the uptake rate constant (k, 0.546 L g h to 0.213 L g h) fitted well with an empirical equation, k = 1/(1.35 + 0.116·Salinity), by treating salinity as a pseudo-competitor. The median lethal concentrations (LCs) of Cu were 269, 224, and 192 μg L at salinity 5, 15, and 30, respectively. At high Cu concentrations (ca. 500 μg L), elevating salinity were much less effective in decreasing Cu bioaccumulation; whereas Cu toxicity increased with salinity. The increased toxicity could be explained by the increases in Cu killing rates (ks), which were estimated to be 0.44-2.08 mg μg h and were presumably due to the osmotic stress caused by the deviation from the optimal salinity of the clams. The other toxicodynamic parameter, internal threshold concentration (C), ranged from 79 to 133 μg g and showed no clear trend with salinity.
不仅影响金属生物累积，还会改变生物体的生理机能和敏感性。在本研究中，我们使用了一个毒代动力学-毒效动力学（TK-TD）模型，来分离并量化盐度对广盐性蛤类光滑河篮蛤中铜（Cu）毒性的双重影响。使用稳定同位素铜作为示踪剂，在受污染环境实际存在的浓度（10-500微克/升）以及5至30的盐度范围内，测定了铜的毒代动力学。在低铜浓度（约10微克/升）时，铜的生物累积随盐度单调下降，通过将盐度视为假竞争剂，摄取速率常数（k，从0.546升/克·小时降至0.213升/克·小时）与经验方程k = 1/(1.35 + 0.116·盐度)拟合良好。在盐度为5、15和30时，铜的半数致死浓度（LC50）分别为269、224和192微克/升。在高铜浓度（约500微克/升）时，提高盐度对降低铜生物累积的效果要小得多；而铜的毒性随盐度增加。毒性增加可以用铜杀灭速率（ks）的增加来解释，估计ks为0.44 - 2.08毫克/微克·小时，这可能是由于蛤类偏离最佳盐度所引起的渗透胁迫。另一个毒效动力学参数，内部阈值浓度（C），范围为79至133微克/克，且未显示出随盐度的明显趋势。
