Department of Renewable Resources, University of Alberta, Edmonton, Alberta, Canada.
Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada.
Environ Toxicol Chem. 2019 Nov;38(11):2472-2479. doi: 10.1002/etc.4557. Epub 2019 Sep 26.
Thallium (Tl) is a trace element associated with base metal mining and processing, but little is known regarding how its toxicity is influenced by water chemistry. In the present study, the 48-h median lethal concentration (LC50) of Tl to Daphnia magna was determined in a standard laboratory water, and toxicity was reassessed under conditions of varying cation (Ca , K , Na ), anion (Cl , HCO ), and dissolved organic matter (DOM) concentrations. The calculated 48-h LC50 of 1.86 mg Tl/L was consistent with previous work on Tl toxicity to D. magna. At the 48-h LC50 concentration, changes in water chemistry had no statistically significant effect on mortality, although there was a trend toward lower Tl toxicity with elevated water K . Test waters containing 10 mM CaCl did not support control survival. The measurement of Tl complexation with DOM using asymmetric flow field flow fractionation confirmed the outcomes of biogeochemical speciation modeling: Tl speciation was relatively unaffected by water chemistry, and the majority of Tl remained in the ionic form across all treatments. These data indicate that Tl toxicity is largely independent of speciation, a property that will greatly simplify risk assessments for this metal in freshwaters. Environ Toxicol Chem 2019;38:2472-2479. © 2019 SETAC.
铊（Tl）是一种与贱金属开采和加工有关的微量元素，但人们对其毒性如何受水化学影响知之甚少。在本研究中，在标准实验室水中测定了大型溞（Daphnia magna）的 48 小时半致死浓度（LC50），并在不同阳离子（Ca、K、Na）、阴离子（Cl、HCO）和溶解有机物（DOM）浓度条件下重新评估了毒性。计算出的 48 小时 LC50 值为 1.86 mg Tl/L，与先前关于 Tl 对 D. magna 的毒性的研究结果一致。在 48 小时 LC50 浓度下，水化学变化对死亡率没有统计学上的显著影响，尽管随着水 K 的升高，Tl 毒性呈下降趋势。含有 10 mM CaCl 的试验用水不能支持对照物的存活。使用不对称流场流分离法测量 DOM 与 Tl 的络合作用证实了生物地球化学形态分类建模的结果：Tl 的形态相对不受水化学的影响，在所有处理中，大部分 Tl 仍以离子形式存在。这些数据表明，Tl 毒性在很大程度上与形态无关，这一特性将大大简化该金属在淡水中的风险评估。环境毒理化学 2019；38：2472-2479。©2019 SETAC。
