Wang Ning, Kunz James L, Ivey Christopher D, Ingersoll Christopher G, Barnhart M Christopher, Glidewell Elizabeth A
United States Geological Survey, Columbia Environmental Research Center, 4200 New Haven Road, Columbia, MO, 65201, USA.
Department of Biology, Missouri State University, 901 South National, Springfield, MO, USA.
Arch Environ Contam Toxicol. 2017 Apr;72(3):449-460. doi: 10.1007/s00244-017-0377-x. Epub 2017 Feb 25.
The objectives of the present study were to develop methods for propagating western pearlshell (Margaritifera falcata) for laboratory toxicity testing and evaluate acute and chronic toxicity of chromium VI [Cr(VI)] to the pearlshell and a commonly tested mussel (fatmucket, Lampsilis siliquoidea at 20 °C or in association with a co-stressor of elevated temperature (27 °C), zinc (50 µg Zn/L), or nitrate (35 mg NO/L). A commonly tested invertebrate (amphipod, Hyalella azteca) also was tested in chronic exposures. Newly transformed pearlshell (~1 week old) were successfully cultured and tested in acute 96 h Cr exposures (control survival 100%). However, the grow-out of juveniles in culture for chronic toxicity testing was less successful and chronic 28-day Cr toxicity tests started with 4 month-old pearlshell failed due to low control survival (39-68%). Acute median effect concentration (EC50) for the pearlshell (919 µg Cr/L) and fatmucket (456 µg Cr/L) tested at 20 °C without a co-stressor decreased by a factor of > 2 at elevated temperature but did not decrease at elevated Zn or elevated NO. Chronic 28-day Cr tests were completed successfully with the fatmucket and amphipod (control survival 83-98%). Chronic maximum acceptable toxicant concentration (MATC) for fatmucket at 20 °C (26 µg Cr/L) decreased by a factor of 2 at elevated temperature or NO but did not decrease at elevated Zn. However, chronic MATC for amphipod at 20 °C (13 µg Cr/L) did not decrease at elevated temperature, Zn, or NO. Acute EC50s for both mussels tested with or without a co-stressor were above the final acute value used to derive United States Environmental Protection Agency acute water quality criterion (WQC) for Cr(VI); however, chronic MATCs for fatmucket at elevated temperature or NO and chronic MATCs for the amphipod at 20 °C with or without elevated Zn or NO were about equal to the chronic WQC. The results indicate that (1) the elevated temperature increased the acute Cr toxicity to both mussel species, (2) fatmucket was acutely more sensitive to Cr than the pearlshell, (3) elevated temperature or NO increased chronic Cr toxicity to fatmucket, and (4) acute WQC are protective of tested mussels with or without a co-stressor; however, the chronic WQC might not protect fatmucket at elevated temperature or NO and might not protect the amphipod at 20 °C with or without elevated Zn or NO.
本研究的目的是开发用于繁殖西部珍珠蚌（Margaritifera falcata）以进行实验室毒性测试的方法，并评估六价铬[Cr(VI)]对珍珠蚌以及一种常用测试贻贝（肥桶蚌，Lampsilis siliquoidea）在20°C时或与升高温度（27°C）、锌（50μg Zn/L）或硝酸盐（35mg NO/L）等共同应激源联合作用下的急性和慢性毒性。一种常用测试的无脊椎动物（双足虾，Hyalella azteca）也进行了慢性暴露测试。新变态的珍珠蚌（约1周龄）成功培养并用于96小时Cr急性暴露测试（对照组存活率100%）。然而，用于慢性毒性测试的幼蚌在养殖中的生长不太成功，以4月龄珍珠蚌开始的28天Cr慢性毒性测试因对照组存活率低（39 - 68%）而失败。在20°C无共同应激源条件下测试的珍珠蚌（919μg Cr/L）和肥桶蚌（456μg Cr/L）的急性半数效应浓度（EC50）在温度升高时降低了>2倍，但在锌升高或硝酸盐升高时未降低。肥桶蚌和双足虾成功完成了28天Cr慢性测试（对照组存活率83 - 98%）。20°C时肥桶蚌的慢性最大可接受毒物浓度（MATC）（26μg Cr/L）在温度升高或硝酸盐升高时降低了2倍，但在锌升高时未降低。然而，20°C时双足虾的慢性MATC（13μg Cr/L）在温度、锌或硝酸盐升高时未降低。无论有无共同应激源测试的两种贻贝的急性EC50均高于用于推导美国环境保护局六价铬急性水质标准（WQC）的最终急性值；然而，温度升高或硝酸盐升高时肥桶蚌的慢性MATC以及20°C时无论锌是否升高双足虾的慢性MATC均约等于慢性WQC。结果表明：（1）温度升高增加了Cr对两种贻贝的急性毒性；（2）肥桶蚌对Cr的急性敏感性高于珍珠蚌；（3）温度升高或硝酸盐升高增加了Cr对肥桶蚌的慢性毒性；（4）急性WQC对有无共同应激源的测试贻贝具有保护作用；然而，慢性WQC可能无法保护温度升高或硝酸盐升高时的肥桶蚌，也可能无法保护20°C时无论锌是否升高的双足虾。
