Qingdao Engineering Research Center for Rural Environment/School of Resources and Environment, Qingdao Agricultural University, Qingdao 266109, China.
School of Resources and Environmental Engineering, Ludong University, Yantai 264025, China.
Ecotoxicol Environ Saf. 2022 Jul 1;239:113633. doi: 10.1016/j.ecoenv.2022.113633. Epub 2022 May 19.
Excessive arsenic in soil and groundwater will not only seriously affect the growth of plants, but also endanger human health through the food chain. However, there are few studies on the effects of metalloid speciation and anion competition on the toxicity of arsenate [As(Ⅴ)]. To investigate the effects of accompanying anions and pH on the toxicity of As(Ⅴ) on wheat root elongation, wheat roots were exposed to the concentrations of As(Ⅴ) in the solution ranged from 0 to 500 mM and different levels of pH (4.5-8.0) and different accompanying anions (HPO, SO, NO and Cl) for five days. The root length of wheat was measured and the biotic ligand model (BLM) was developed to predict the potential toxicity of As(V) speciation to wheat roots. The results illustrated that EC50 of total As(V) (EC50{As(Ⅴ)}) values increased from 6.88 to 33.9 μM with increasing pH values from 4.5 to 8.0, suggesting that increasing pH alleviated As(Ⅴ) toxicity. The EC50{AsO} and EC50{HAsO} values increased from 0.001 to 4342 μM and from 0.0214 to 27.4 μM, respectively, while the EC50{HAsO} and EC50{HAsO} values sharply decreased from 6.62 to 2.68 μM and from 41.8 μM to 5.34 nm, respectively, when pH increased from 4.5 to 8.0. The toxicity of As(Ⅴ) decreased as the HPO and SO activities increased but not when the activities of NO and Cl increased, indicating that SO and HPO showed competitive effects with As(Ⅴ) on the binding sites. Based on BLM theory, the stability constants were obtained: [Formula: see text] = 3.70; [Formula: see text] = 4.08; [Formula: see text] = 4.77; [Formula: see text] = 6.50; [Formula: see text] = 2.09 and [Formula: see text] = 1.86, with f= 0.30 and β = 1.73. Results implied that BLM performed well in As(Ⅴ) toxicity prediction when coupling toxic species AsO, HAsO, HAsO, and HAsO, and the competition of SO and HPO for binding sites. The current study provides a useful tool to accurately predict As(V) toxicity to wheat roots.
土壤和地下水中过量的砷不仅会严重影响植物的生长，还会通过食物链危害人类健康。然而，目前关于类金属形态和阴离子竞争对砷酸盐[As（V）]毒性的影响研究较少。为了研究伴随阴离子和 pH 值对小麦根伸长的砷酸盐[As（V）]毒性的影响，将小麦根暴露于溶液中 As（V）浓度范围为 0 至 500 mM 以及不同 pH 值（4.5-8.0）和不同伴随阴离子（HPO、SO、NO 和 Cl）的条件下 5 天。测量小麦根长，并建立生物配体模型（BLM）以预测 As（V）形态的潜在毒性对小麦根的影响。结果表明，随着 pH 值从 4.5 增加到 8.0，总砷[As（V）]的 EC50 值（EC50{As（Ⅴ）}）从 6.88 增加到 33.9 μM，表明 pH 值增加缓解了 As（V）的毒性。当 pH 值从 4.5 增加到 8.0 时，AsO 和 HAsO 的 EC50{AsO}和 EC50{HAsO}值分别从 0.001 增加到 4342 μM 和从 0.0214 增加到 27.4 μM，而 HAsO 和 HAsO 的 EC50{HAsO}和 EC50{HAsO}值分别从 6.62 急剧下降到 2.68 μM 和从 41.8 μM 下降到 5.34 nM。As（V）的毒性随着 HPO 和 SO 活性的增加而降低，但当 NO 和 Cl 活性增加时则不会，这表明 SO 和 HPO 对与 As（V）结合位点表现出竞争效应。基于 BLM 理论，获得了稳定常数：[Formula: see text] = 3.70；[Formula: see text] = 4.08；[Formula: see text] = 4.77；[Formula: see text] = 6.50；[Formula: see text] = 2.09 和 [Formula: see text] = 1.86，f= 0.30 和 β = 1.73。结果表明，当结合有毒物种 AsO、HAsO、HAsO 和 HAsO 时，BLM 在预测 As（V）对小麦根的毒性方面表现良好，并且 SO 和 HPO 对结合位点的竞争。本研究为准确预测 As（V）对小麦根的毒性提供了有用的工具。
