Todd Andrew S, Brinkman Stephen, Wolf Ruth E, Lamothe Paul J, Smith Kathleen S, Ranville James E
U.S. Geological Survey, Box 25046, MS 964, Denver, Colorado 80225, USA.
Environ Toxicol Chem. 2009 Jun;28(6):1233-43. doi: 10.1897/08-252.1.
The objective of the present study was to employ an enriched stable-isotope approach to characterize Zn uptake in the gills of rainbow trout (Oncorhynchus mykiss) during acute Zn exposures in hard water (approximately 140 mg/L as CaCO3) and soft water (approximately 30 mg/L as CaCO3). Juvenile rainbow trout were acclimated to the test hardnesses and then exposed for up to 72 h in static exposures to a range of Zn concentrations in hard water (0-1000 microg/L) and soft water (0-250 microg/L). To facilitate detection of new gill Zn from endogenous gill Zn, the exposure media was significantly enriched with 67Zn stable isotope (89.60% vs. 4.1% natural abundance). Additionally, acute Zn toxicity thresholds (96-h median lethal concentration [LC50]) were determined experimentally through traditional, flow-through toxicity tests in hard water (580 microg/L) and soft water (110 microg/L). Following short-term (< or =3 h) exposures, significant differences in gill accumulation of Zn between hard and soft water treatments were observed at the three common concentrations (75, 150, and 250 microg/L), with soft water gills accumulating more Zn than hard water gills. Short-term gill Zn accumulation at hard and soft water LCS0s (45-min median lethal accumulation) was similar (0.27 and 0.20 microg/g wet wt, respectively). Finally, comparison of experimental gill Zn accumulation, with accumulation predicted by the biotic ligand model, demonstrated that model output reflected short-term (<1 h) experimental gill Zn accumulation and predicted observed differences in accumulation between hard and soft water rainbow trout gills. Our results indicate that measurable differences exist in short-term gill Zn accumulation following acclimation and exposure in different water hardnesses and that short-term Zn accumulation appears to be predictive of Zn acute toxicity thresholds (96-h LC50s).
本研究的目的是采用富集稳定同位素方法，以表征硬水（约140mg/L碳酸钙）和软水（约30mg/L碳酸钙）中急性锌暴露期间虹鳟（Oncorhynchus mykiss）鳃对锌的摄取情况。将幼年虹鳟适应测试硬度，然后在静态暴露中于硬水（0 - 1000μg/L）和软水（0 - 250μg/L）中的一系列锌浓度下暴露长达72小时。为便于从内源性鳃锌中检测新的鳃锌，暴露介质用67Zn稳定同位素显著富集（自然丰度为89.60%，而天然丰度为4.1%）。此外，通过传统的流水毒性试验，在硬水（580μg/L）和软水（110μg/L）中实验测定了急性锌毒性阈值（96小时半数致死浓度[LC50]）。短期（≤3小时）暴露后，在三种常见浓度（75、150和250μg/L）下，观察到硬水和软水处理之间鳃对锌的积累存在显著差异，软水中鳃积累的锌比硬水中的更多。硬水和软水LC50s（45分钟半数致死积累量）下的短期鳃锌积累相似（分别为0.27和0.20μg/g湿重）。最后，将实验性鳃锌积累与生物配体模型预测的积累进行比较，结果表明模型输出反映了短期（<1小时）实验性鳃锌积累，并预测了硬水和软水虹鳟鳃之间积累的观察差异。我们的结果表明，在适应和暴露于不同水硬度后，短期鳃锌积累存在可测量的差异，并且短期锌积累似乎可预测锌急性毒性阈值（96小时LC50s）。
