Ding Tengda, Zhang Jianying, Ni Wanmin, Li Juying
College of Chemistry and Environmental Engineering, Shenzhen University, Shenzhen, 518060, China.
Environmental Science Institute, Zhejiang University, Hangzhou, 310058, China.
Ecotoxicology. 2017 Mar;26(2):202-210. doi: 10.1007/s10646-016-1755-2. Epub 2017 Jan 2.
The toxicity and bioavailability of single arsenic species have been widely investigated, however, the biological effects of mixed arsenic species co-existing in natural waters still remain unknown. The objective of this work was to discern the adverse effects of combined arsenite (As(III)) and dimethylarsenic acid (DMA) on diatom Nitzschia palea. The combined ecotoxicity of As(III) and DMA on N. palea was observed to be time-dependent and showed dose-effect relation. The toxicity of DMA and As(III) mixture was higher than individual DMA or As(III) when the As(III) concentration was in the range of 0.085-0.316 mg L. As the As(III) concentration increased from 0.487 to 0.858 mg L, the antagonistic effect was found, which could be due to the higher thiols contents in the thiol-containing proteins (e.g., frustulins, silaffins and other glycoproteins). The content of malondialdehyde (MDA) in the treatment of mixed arsenic species was found to be at the same level compared to the As-free control after 72 h of exposure, indicating that the co-toxicity of As(III) and DMA on diatom frustules was not significant. Furthermore, the increase of frustule formation rate in the mixture of EC As(III)-EC DMA at 72 h exposure time indicated that the damaged diatom cell walls was likely repaired gradually. The results from this study suggested that the effects of co-existed arsenic species were concentration-specific and should be considered in the risk assessment of arsenic and development of water quality criteria for the protection of aquatic ecosystems.
单一砷形态的毒性和生物有效性已得到广泛研究，然而，天然水体中共存的混合砷形态的生物学效应仍然未知。这项工作的目的是识别亚砷酸盐（As(III)）和二甲基砷酸（DMA）联合对硅藻菱形藻的不利影响。观察到As(III)和DMA对菱形藻的联合生态毒性具有时间依赖性，并呈现剂量效应关系。当As(III)浓度在0.085 - 0.316 mg L范围内时，DMA和As(III)混合物的毒性高于单独的DMA或As(III)。随着As(III)浓度从0.487增加到0.858 mg L，发现了拮抗作用，这可能是由于含硫醇蛋白质（如硅藻壳蛋白、硅甲藻素和其他糖蛋白）中硫醇含量较高。暴露72小时后，发现混合砷形态处理中的丙二醛（MDA）含量与无砷对照处于同一水平，这表明As(III)和DMA对硅藻壳的共同毒性不显著。此外，在72小时暴露时间下，EC As(III)-EC DMA混合物中硅藻壳形成率的增加表明受损的硅藻细胞壁可能逐渐得到修复。这项研究的结果表明，共存砷形态的影响具有浓度特异性，在砷的风险评估和保护水生生态系统的水质标准制定中应予以考虑。
