Application of enriched stable isotope technique to the study of copper bioavailability in Daphnia magna

The biokinetics of Cu in Daphnia magna, including dissolved uptake, assimilation and e ux, has been determined using a gamma 67Cu radiotracer methodology. However, this gamma emitting radioisotope is not readily available due to its very short half-life. In the present study, we employed a stable isotope tracer (65Cu) to determine the Cu biokinetics and compared our results to those determined using 67Cu. The dissolved uptake rate constant of 65Cu was 3.36 L/(g day), which is higher than that of 67Cu (1.32 L/(g day)). With increasing food concentrations from 2 104 to 1 105 cells/mL, the Cu assimilation e ciency (AE) decreased from 46% to 11%, compared to a decrease from 27% to 16% when determined using 67Cu. The e ux of Cu from Daphnia magna was quantified following both dissolved and dietary uptake. The e ux of waterborne Cu was comparable to that of dietborne Cu and the e ux rate constant (0.32–0.52 day??1) was higher than that determined by 67Cu (0.19–0.20 day??1). By considering di erent water properties and handling procedure between the two experiments, we believe that these di erences are reasonable. Overall, this study demonstrated that the enriched stable isotope tracer technique is a powerful tool to investigate metal bioavailability and maybe a good alternative to radioactive measurements.     

8种典型PhACs在水中的赋存、生态风险及其对大型溞的影响

检测了8种典型的药物活性化合物(PhACs)在污水处理厂尾水受纳河流中的赋存情况.结果显示8种PhACs夏、冬两季总浓度范围分别为27.6～226.4 ng·L~(-1)和56.6～368.8 ng·L~(-1),其中咖啡因的浓度最高(16.2～125.8 ng·L~(-1)),其次是罗红霉素(3.3～89.2 ng·L~(-1))和布洛芬(3.6～59.2 ng·L~(-1)). 8种PhACs对绿藻、溞类和鱼类的总体生态风险(MRQ)在夏、冬两季分别为1.51、 0.08、 5.68和8.34、 0.22、 6.45,其中酮康唑、红霉素和布洛芬对藻类、溞类和鱼类MRQ的贡献率分别达到了49%、 85%和92%以上.从敏感物种来看,冬季绿藻对PhACs最为敏感,夏季鱼类对PhACs最为敏感.环境浓度下PhACs对大型溞21 d混合暴露实验结果显示:混合PhACs能够显著干扰大型溞的生长、生殖情况,显著提升了大型溞生殖能力和游泳活性,降低了心脏和胸肢跳动频率.     

大型蚤急性毒性试验的质量控制

为加强大型蚤急性毒性试验的质量控制,采用重铬酸钾作为参考毒物分析了不同日龄母蚤所产幼蚤的毒性效应变化。研究发现,在大型蚤急性毒性试验中,对于在11~56日龄期间的母蚤,以35日龄母蚤所产幼蚤对重铬酸钾的敏感度最高,47日龄母蚤所产幼蚤的敏感度最低。在一定范围内,提高稀释水硬度可显著降低大型蚤对重铬酸钾的敏感度。重铬酸钾的24h-EC ₅₀值的实验室精密度以29~42日龄母蚤组所产幼蚤最好,其次为15~28日龄母蚤组;经t检验,大于42日龄母蚤组所产幼蚤对重铬酸钾24h-EC ₅₀值与15~28日龄母蚤组有显著性差异(P＜0.05),与29~42日龄母蚤组有高度显著性差异(P＜0.01),表明以20℃为大型蚤培养温度时,大型蚤毒性试验宜选用15~42天母蚤所产幼蚤。进行大型蚤急性毒性试验时,应定期使用参考毒物检查毒性试验的实验精密度并运用质量控制图来验证持续的实验室能力。     

海上石油生产水的水生生态毒性

采用水生生态毒理学常用的大型蚤(Daphnia magma)和斑马鱼(Brachydaniorerio)以及毒性单位(Tua)法对渤海海上油田的石油生产水进行生态毒性评价和分级.结果表明,这些石油生产水对大型蚤和斑马鱼均表现出一定的毒性效应.其中,水样1和水样3的毒性较大,对大型蚤的Tua分别为151.52和70.96.而对斑马鱼的Tua分别为2.41和2.12.水样3虽经处理,但其生态毒性并未得到明显的改善.水样2对大型蚤和斑马鱼都属于低毒等级,其Tua依次分别为4.39和1.97.可见,大型蚤和斑马鱼可以作为海上石油生产永生态毒性的监测指标,但在生态风险评价中大型蚤比斑马鱼更为灵敏.