万山矿区土壤汞对蚯蚓的生物有效性研究

doi:10.11934/j.issn.1673-4831.2016.01.020

摘要/Abstract

摘要：

以威廉环毛蚓(Pheretima guillemi)为试验生物,研究贵州万山矿区水稻土中汞[w(总汞)为0.14~76 mg·kg^-1,w(甲基汞)为0.65~3.8μg·kg^-1]的生物有效性。暴露试验结果表明,矿区土壤中甲基汞的生物富集因子(BAF)为5.37~17.55,高于无机汞的生物富集因子(0.14~1.14),说明甲基汞生物有效性比无机汞更高,具有潜在的生物放大效应。对蚯蚓体内汞形态的分析表明,蚯蚓体内甲基汞占总汞比例为0.26%~4.23%,高于土壤中甲基汞占总汞比例(< 0.1%)。随着土壤中汞浓度的增加,蚯蚓体内w(无机汞)(0.20~10.20 mg·kg^-1)和w(甲基汞)(7.2~47.8μg·kg^-1)增加。土壤无机汞浓度与蚯蚓体内无机汞浓度之间呈极显著线性相关(P<0.01),但土壤甲基汞浓度与蚯蚓体内甲基汞浓度之间则不存在显著相关关系(P>0.05)。综合文献调研结果,发现土壤无机汞浓度能较好地预测蚯蚓体内无机汞的富集。尽管万山矿区汞被认为是"惰性汞",但研究表明这些汞对蚯蚓仍具有较高的有效性,并可能在陆生生态系统中对蚯蚓捕食者产生潜在的生态风险。

关键词: 汞矿区, 总汞, 甲基汞, 蚯蚓, 生物有效性

Abstract:

Earthworms(Pheretima guillemi) were used as subject in an exposure experiment in mercury contaminated paddy soil, with inorganic mercury(IHg) ranging from 0.14-76 mg·kg^-1 and methylmercury(MeHg), from 0.65-3.8μg·kg^-1, in a mining area of Wanshan, Guizhou Province. Substantial IHg and MeHg bioaccumulation, i.e., 0.20-10.20 mg·kg^-1 and 7.2-47.8μg·kg^-1,were observed in earthworms after twenty-one days of exposure. Obviously, the bioaccumulation factor(BAFs) for MeHg(5.37-17.55) was 9.9-75 fold higher than that for IHg(0.14-1.14), which indicates that MeHg is much higher in bioavailability than IHg and possess potential biomagnification effect. Analysis of forms of Hg in earthworms reveals that MeHg contributed 0.26%-4.23% of the total mercury in the earthworm, while it did only < 0.1% in the soil. With rising Hg concentration in the soil, MeHg and IHg both increased in the earthworms. MeHg and IHg BAFs were little influenced by soil mercury concentrations, although the proportion of MeHg in earthworm tended to decrease with increasing MeHg concentration in the soil. Furthermore, IHg content in the earthworms displayed an apparent linear relationship with soil mercury concentration, explaining 94% of the variation of IHg in the earthworms. Yet no significant relationship was observed for MeHg. After a comprehensive review of relevant literature and data, it was found that soil inorganic mercury concentration may serve as an indicator for bio-accumulation of IHg in earthworms. Nevertheless, although mercury in the mining-area is thought to be "inert Hg", this study demonstrated that it's still quite highly bioavailable to earthworms, and may pose a potential ecological risk to predators of earthworms in the terrestrial environment.

Key words: Hg-mining area, total mercury, methylmercury, earthworm, bioavailability

中图分类号:

赵杰, 李程程, 杨周生, 党菲, 周东美. 万山矿区土壤汞对蚯蚓的生物有效性研究[J]. 生态与农村环境学报, 2016, 32(1): 120-125.

ZHAO Jie, LI Cheng-cheng, YANG Zhou-sheng, DANG Fei, ZHOU Dong-mei. Bioavailability of Mercury to Earthworm(Pheretima guillemi) in Soil of the Wanshan Mining District[J]. Journal of Ecology and Rural Environment, 2016, 32(1): 120-125.

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