沉积物砷污染对沉水植物泌氧作用的抑制及其机制的研究

The dose-effect relationship between arsenic in sediment and the physiological process of submerged plants have been well concerned in pollution ecology. While radial oxygen loss could change the speciation and concentration of arsenic by influencing the property of rhizosphere sediment, it can also be retained by the toxicity effect of arsenic in sediment. The mechanism of the interactions between arsenic species and concentration in sediment, radial oxygen loss, and rhizosphere sediment property has not been well understood yet. This project cultivates submerged plant, Vallisneria spiralis L., in aquatic solution and sediment with different arsenic level and measures the variation of radial oxygen loss strength, physiological properties, toxicity effects, rhizosphere area, sediment properties, and the speciation and concentration of arsenic between different experimental groups in order to answer the following questions: (1) what's the influence of arsenic on radial oxygen loss and what is the mechanism behind it? (2) in contaminated sediment, how will radial oxygen loss influence the property and arsenic speciation in the rhizosphere sediment and whether the inhibition of radial oxygen loss will influence the area of rhizosphere in sediment? Answering the questions above will deepen the understanding of the ecological risk of arsenic in sediment, improve the knowledge in the biogeochemical cycle of arsenic in sediment, and provide fundamental scientific support to the ecological restoration of hydrological ecosystem.

沉积物中砷与沉水植物生理过程的剂量效应关系在污染生态学中受到广泛关注。泌氧作用既可以通过改造根际沉积物的理化性质影响砷的形态浓度，也会受到砷毒性效应的抑制。沉积物中砷的形态浓度、沉水植物泌氧、根际沉积物性质三者之间的相互影响及作用机制仍需进一步探索。本项目通过室内培养的方式，将苦草根系暴露在砷形态及浓度不同的水溶液及沉积物中，通过对比不同处理组间泌氧强度、生理指标、毒性效应、根际沉积物范围、根际沉积物性质以及根际沉积物中砷浓度形态等指标间的差异揭示以下问题：①砷胁迫下沉水植物根系泌氧作用会发生什么变化？生理机制是什么？②砷污染沉积物中，泌氧作用对根际沉积物的理化性质及砷化合物的形态、浓度有什么样的影响？泌氧抑制是否会影响根际沉积物的范围？了解以上问题将加深对砷污染沉积物生态风险的认识，对理解沉积物中砷的生物地球化学循环有重要意义，为水体生态修复提供一些基础科学支持。

沉积物中砷与沉水植物生理过程的剂量效应关系在污染生态学中受到广泛关注。泌氧作用既可以通过改造根际沉积物的理化性质影响砷的形态浓度，也会受到砷毒性效应的抑制。沉积物中砷的形态浓度、沉水植物泌氧、根际沉积物性质三者之间的相互影响及作用机制仍需进一步探索。本项目通过室内培养的方式，将苦草根系暴露在砷形态及浓度不同的水溶液及沉积物中，开展不同处理组间泌氧强度、生理指标、毒性效应、根际沉积物性质以及根际沉积物中砷浓度形态等指标间的差异研究。研究结果显示，砷胁迫下沉水植物根际泌氧作用随胁迫浓度的升高会出现先加强、后减弱的趋势，其生理机制与砷暴露导致的氧化胁迫以及根系表面的损伤有关。砷污染沉积物中，砷浓度的升高一方面对苦草根系的生物量、根系活力、根系泌氧等生理功能造成损伤；一方面仅在极高浓度时才对苦草叶片的生理功能及光合作用产生影响。沉积物中氧化还原电位随砷浓度升高而降低，同时间隙水中三价砷浓度所占比例逐渐升高。磷元素对苦草抵抗砷胁迫有显著的辅助作用。本研究结果将加深对砷污染沉积物生态风险的认识，对理解沉积物中砷的生物地球化学循环有重要意义，为水体生态修复提供一些基础科学支持。