Cadmium-induced toxicity to amphibian tadpoles might be exacerbated by alkaline not acidic pH level

Ecotoxicology and Environmental Safety

Yingchao Hu¹  Hongliang Lu²  Zhihua Lin²  Qinyuan Meng²  Chunquan Kang² 

[1] Correspondence to: No.2318 , Yuhangtang Rd, Yuhang District, Hangzhou 311121, Zhejiang, China.;Key Laboratory of Hangzhou City for Ecosystem Protection and Restoration, School of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou 311121, Zhejiang, China;

关键词: Rana zhenhaiensis;    Cd exposure;    pH level;    Oxidative stress;    Genotoxicity;   

DOI  :  

来源: DOAJ

【 摘 要 】

Heavy metal pollution in natural water bodies generally interacting with other environmental stressors produces toxic effects on aquatic organisms. However, toxicological studies exploring interactive effects of these stressors are still limited. Here, tadpoles of the Zhenhai brown frog (Rana zhenhaiensis) were exposed to a 3 × 3 factorial combination, with three cadmium (Cd) concentrations (0, 10 and 100 μg/L) and three pH levels (5.0, 7.23 and 9.0) throughout the developmental period to assess combined toxic effects of Cd × pH on tadpole growth, development and physiology. Nearly all measured traits [including survival, metamorphosis and abnormality rate, metamorphosis time, post-metamorphic size, hepatic metal content, locomotor performance, antioxidant enzyme activity, and erythrocytic nuclear abnormality (ENA) frequency] were affected by Cd exposure, indicating notable Cd-induced toxicity to R. zhenhaiensis tadpoles. The pH level and its interaction with Cd also had significant impacts on most measured traits, such as survival rate, metamorphosis time, froglet jumping distance, hepatic Cd content, ENA frequency. Acidic (or alkaline) environment itself was toxic to tadpoles. However, high pH (but not low pH) level appeared to exacerbate Cd-induced toxicity to tadpoles. Excess free hydrogen ions under acidic environments might inhibit Cd2+ ions binding to cell surface, which reduced Cd accumulation in tissues. Under alkaline environments, other forms of Cd complexes in the aqueous phase probably contributed to promoting Cd accumulation. Our results indicated that Cd exposure could interact with different pH levels, producing diverse combined toxicities to amphibian larvae.

【 授权许可】

Unknown