外源洛克沙胂对水生态系统砷蓄积及底泥微生物生长的影响

为探明洛克沙胂(ROX)对水生态系统的毒性效应,采用模拟水生态系统,研究了外源添加不同浓度洛克沙胂(0、10、20、40、80和160 mg·L-1)对水生态系统砷含量及底泥微生物生长的影响。结果表明,水体及底泥砷含量随外源ROX用量增加而增加,但随暴露时间延长水体砷含量降低的同时底泥砷含量逐渐增加。金鱼藻和鲫鱼体内均出现明显砷蓄积现象,且160 mg·L-1ROX处理的水生态系统鲫鱼毒害效应明显,暴露1 d的死亡率为100%。金鱼藻对砷具有较强的富集能力,暴露32 d后砷富集量达398.1~1 538.91 mg·kg-1。不同浓度ROX对底泥真菌、细菌和反硝化细菌生长均具有不同程度的抑制效应,而对放线菌和氨化细菌生长具有一定的促进作用,且低浓度ROX(10 mg·L-1)对放线菌生长的促进作用明显。总体上,外源ROX进入水生态系统导致水体砷污染的同时在生物及非生物媒介中再次迁移、分配和蓄积,进而对鲫鱼及部分底泥微生物生长产生毒害。

Impacts of Exogenous Roxarsone on Arsenic Accumulation and Growth of Sediment Microorganisms in Aquatic Microcosms

To investigate the toxic effects of roxarsone (ROX) on the aquatic ecosystems, the simulated aquatic microcosms were employed to study the effects of exogenous ROX on arsenic accumulation and growth of microorganisms in sediments. Six ROX concentrations including 0, 10, 20, 40, 80 and 160 mg·L^-1 were used in this study. Results showed that arsenic content in water column and sediment increased with the amount of ROX application. However, as the ROX exposure time elapsed, the arsenic content decreased in the water column but increased in the sediment. In addition, arsenic accumulation in the sharksuckers and hornwort bodies was observed. When the aquatic ecosystem was treated with the ROX concentration of 160 mg·L^-1, the sharksuckers showed a significant ROX toxicity with a death rate of 100% within one day. It was observed that hornwort had higher capacity of arsenic accumulation with a concentration range from 398.1-1538.91 mg·kg^-1 As after 32 d exposure. Different concentrations of ROX can inhibit the growth of fungus, bacteria and denitrifying bacteria, whereas the growth of actinomyces and ammonification bacteria in sediment were promoted as exposed to the ROX environment. Furthermore, the growth of actinomyces in sediment was promoted significantly at 10 mg·L^-1 ROX. In summary, exogenous ROX polluted water environment and re-transported and re-accumulated in different biotic and abiotic organisms, which resulted in toxicity of sharksucker and some microorganisms in the sediment.