Abstract：
Barium (Ba) dissolution and mobilization in groundwater are predominantly controlled by sulfate because of the low solubility of barium sulfate (BaSO4) minerals. Naturally present at low concentrations in groundwater, elevated concentrations of Ba can occur as a result of anthropogenic activities, including use of barite in drill operations, and geogenic sources such as leaching from geological formations. No toxicity data exist for Ba with groundwater organisms (stygofauna) to assess the risk of elevated Ba concentrations. The present study measured Ba toxicity to two stygobiont Cyclopoida species: one collected from Wellington and the other from Somersby, New South Wales, Australia. Toxicity was measured as cyclopoid survival over 2, 4, 7, 14, 21, and 28 days in waters of varying sulfate concentration (<1-100 mg SO4/L). When sulfate was present, dissolved Ba concentrations decreased rapidly in toxicity test solutions forming a BaSO4 precipitate until dissolved sulfate was depleted. Barium in excess of sulfate remained in the dissolved form. The toxicity of Ba to cyclopoids was clearly attributed to dissolved Ba. Precipitated Ba was not toxic to the Wellington cyclopoid species. Toxicity values for dissolved Ba for the Wellington and Somersby cyclopoid species included a (21-day) no-effect concentration of 3.3 mg/L and an effective concentration to cause 5% mortality of 4.8 mg/L (at 21 days). Elevated dissolved Ba concentrations due to anthropogenic and/or biogeochemical processes may pose a risk to groundwater organisms. Further toxicity testing with other stygobiont species is recommended to increase the data available to derive a guideline value for Ba that can be used in contaminant risk assessments for groundwaters. Environ Toxicol Chem 2024;00:1-14. © 2024 The Author(s). Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.
摘要：
由于硫酸钡（BaSO4）矿物的溶解度低，钡（Ba）在地下水中的溶解和动员主要受硫酸盐控制。自然以低浓度存在于地下水中，Ba的浓度升高可能是人为活动的结果，包括在钻井作业中使用重晶石，和地质来源，如地质构造的浸出。对于Ba与地下水生物（stypogorouna）没有毒性数据来评估Ba浓度升高的风险。本研究测量了Ba对两种Cyclopoida物种的毒性：一种从惠灵顿收集，另一种从Somersby收集，新南威尔士州,澳大利亚。毒性测量为在不同硫酸盐浓度（<1-100mgSO4/L）的水中2、4、7、14、21和28天的摆线体存活。当硫酸盐存在时，溶解的Ba浓度在毒性测试溶液中迅速下降，形成BaSO4沉淀，直到溶解的硫酸盐耗尽。超过硫酸盐的钡以溶解形式保留。Ba对环状物的毒性显然归因于溶解的Ba。沉淀的Ba对惠灵顿环形动物没有毒性。惠灵顿和Somersby摆线物种的溶解Ba的毒性值包括（21天）3.3mg/L的无作用浓度和导致5％死亡率为4.8mg/L的有效浓度（21天）。由于人为和/或生物地球化学过程导致的溶解Ba浓度升高可能对地下水生物构成风险。建议使用其他stygobiont物种进行进一步的毒性测试，以增加可用的数据，以得出Ba的指导值，该指导值可用于地下水的污染物风险评估。环境毒物化学2024；00：1-14。©2024作者（S）。WileyPeriodicalsLLC代表SETAC出版的环境毒理学和化学。
