海洋酸化条件下Cd2+和Hg2+对斧文蛤幼贝急性毒性效应

为研究在海洋酸化条件下重金属污染物对滩涂贝类的影响,采用半静态急性毒性实验的研究方法,利用海洋酸化人工模拟系统,分析了不同酸化条件下(对照组pH 8.20、酸化组pH分别为7.80、7.60和7.40)Cd2+和Hg2+对斧文蛤(Meretrix lamarckii)幼贝急性毒性效应的影响。实验结果表明:在实验设定的海洋酸化范围内,单一的海洋酸化对斧文蛤幼贝的存活没有显著性影响,但海洋酸化显著增强了Cd2+和Hg2+的急性毒性。与对照组相比,酸化组Cd2+和Hg2+的毒性随着酸化程度的加剧而呈现出逐渐增强的趋势; Cd2+和Hg2+均在pH 7.40时对斧文蛤的毒性最强,其96h半致死(96h LC50)浓度分别为4.068 mg/L(Cd2+)和10.332 mg/L(Hg2+),明显低于pH 8.20、7.80和7.60时其对斧文蛤幼贝的96h LC50浓度(其值分别为Cd2+ 6.458、5.947、4.728 mg/L和Hg2+ 12.027、11.169、10.595 mg/L)。研究有助于丰富海洋酸化与重金属毒理作用在海洋贝类中的研究内容,为斧文蛤资源恢复和海洋环境保护提供科学依据。

EFFECTS OF OCEAN ACIDIFICATION ON THE ACUTE TOXICITY OF Cd2+ AND Hg2+ TO JUVENILE MERETRIX LAMARCKII

Like the greenhouse effect, ocean acidification (OA) is an environmental problem caused by increased emissions of anthropogenic carbon dioxide (CO2). The reduced pH of the seawater will seriously affect the growth, development and reproduction of marine organism, and thus threaten the marine ecosystem. There have been great concerns about the impact of heavy metal pollution on the marine biological and ecological system in recent years. However, up to date little is known about the combined effects of ocean acidification and heavy metal pollution on shellfish. Using artificial simulation of ocean acidification and semi static acute toxicity test we investigated whether ocean acidification would affect the acute toxicity of Cd2+ and Hg2+ on juvenile M. lamarckii. Experiments were carried out at pH 8.20, 7.80, 7.60 and 7.40 respectively. We found that although ocean acidification alone did not change the survival rate, it significantly increased the toxicity of Cd2+ and Hg2+ to juvenile M. lamarckii compared to the control. Moreover the to-xicity of Cd2+ and Hg2+ rose as the acidity of seawater increased, and the two heavy metal ions were the most toxic at the lowest experimental pH 7.4. The corresponding 96h LC50 concentrations for Cd2+ and Hg2+ were 4.068 and 10.332 mg/L respectively. As the pH of seawater increased the toxicity was reduced in other experimental trials. For Cd2+, the 96h LC50 concentrations were 4.728 mg/L at pH 7.6, 5.947 mg/L at pH 7.8, and 6.458 mg/L at pH 8.2, and the 96h LC50 for Hg2+ were 10.595, 11.169 and 12.027 mg/L respectively. Compared to the control, the toxicity of Cd2+ and Hg2+ on juvenile M. lamarckii increased by about 1.4 and 1.2 times respectively at lower pH. Our results shed lights on the inte-ractive effects between ocean acidification and heavy metal pollution, therefore would contribute to the protection and restoration of M. lamarckii population.