Toxicity of cerium and thorium on Daphnia magna

Yuhui Ma; Jingkun Wang; Can Peng; Yayun Ding; Xiao He; Peng Zhang; Na Li; Tu Lan; Dongqi Wang; Zhaohui Zhang; Fuhong Sun; Haiqing Liao; Zhiyong Zhang

doi:10.1016/j.ecoenv.2016.09.006

Toxicity of cerium and thorium on Daphnia magna

Ecotoxicol Environ Saf. 2016 Dec:134P1:226-232. doi: 10.1016/j.ecoenv.2016.09.006. Epub 2016 Sep 14.

Authors

Yuhui Ma¹, Jingkun Wang², Can Peng³, Yayun Ding¹, Xiao He¹, Peng Zhang¹, Na Li¹, Tu Lan¹, Dongqi Wang¹, Zhaohui Zhang³, Fuhong Sun⁴, Haiqing Liao⁵, Zhiyong Zhang⁶

Affiliations

¹ Key Laboratory for Biological Effects of Nanomaterials and Nanosafety, Key Laboratory of Nuclear Radiation and Nuclear Energy Technology, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China.
² Jiangsu Province Metallurgical Design Institute Co., Ltd, Jiangsu, 210007, China.
³ School of public health, University of South China, Hunan, 421001, China.
⁴ Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China.
⁵ Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China. Electronic address: liaohaiqing@vip.gyig.ac.cn.
⁶ Key Laboratory for Biological Effects of Nanomaterials and Nanosafety, Key Laboratory of Nuclear Radiation and Nuclear Energy Technology, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China. Electronic address: zhangzhy@ihep.ac.cn.

PMID: 27639197
DOI: 10.1016/j.ecoenv.2016.09.006

Abstract

Cerium (Ce) and thorium (Th) are always thought to be chemically similar and have comparable toxic properties on living organisms. In the present study, the acute and chronic toxicity of these two elements to freshwater crustacean Daphnia magna were investigated in the modified reconstituted water (6mg/L KCl, 123mg/L MgSO₄·7H₂O, and 294mg/L CaCl₂·2H₂O in Milli-Q water, pH 7.8). It seemed that Ce and Th had comparable acute toxicity on Daphnia: 24/48h EC₅₀ for Th and Ce were 7.3/4.7μM and 16.4/10.7μM, respectively. However, Ce was present as soluble ions while all of Th was present as particulate ThO₂ in the exposure medium. Considering their different chemical forms and bioavailability, the toxic mechanisms of Ce³⁺ and ThO₂ on Daphnia would be totally different. To our knowledge, this is the first time to investigate the aquatic toxicity of thorium and cerium based on their actual chemical speciation in the exposure medium. The results also suggest that more attention should be paid on the detrimental effect of Th in the form of particulate ThO₂.

Keywords: Acute toxicity; Cerium; Chemical speciation; Chronic toxicity; Daphnia magna; Thorium.