水位过程-内源负荷-生物作用对白洋淀水质的影响规律与调控方法

In view of the prominent problems of internal nitrogen and phosphorous pollution in Baiyangdian Lake, we investigate the characteristics of water quality and sediment pollution and the distribution of biome in Baiyangdian Lake. Through analysis of the environmental characteristics and perturbation factors of sediment-water interface, we identify the relationship of the distribution of nutrients and the microenvironment of the interface. In situ FTIR spectroscopy and mass spectrometry, isotope tracing techniques and high-throughput sequencing methods will be used to study the physical, chemical and biological reaction processes of nitrogen and phosphorus at the interface, to explore the law of phosphorus deposition and release, and to reveal the mechanism of nitrogen transport and transformation. The relationship between water level process, endogenous load and biological effects will be identified by indoor simulation experiments and field experiments to further investigate the effect of the three on the water quality of Baiyangdian Lake, and to determine the distribution of nutrients in the water phase, mud phase, gas phase and biological phase. The influences of water level rise and fall, endogenous load increase and decrease, and biological effect enhancement and attenuation on the water quality of Baiyangdian Lake will be determined. The appropriate range and the best status of the water level, endogenous load and biological role will be found out. Based on safety protection of water quality in Baiyangdian Lake, the technology of water level regulation, endogenous reduction and bioenhancement will be suggested. The research could provide technical support for the protection of Baiyangdian water environment and the sustainable development of Xiong'an New District, and provide theoretical guidance for the control of endogenous pollution of shallow grass-lakes.

针对白洋淀内源氮和磷污染的突出问题，调查白洋淀水质和底质污染以及生物群落分布，分析沉积物—水界面环境特征与扰动因素，辨识氮磷营养盐形态分布及其与界面微环境的关系。拟采用原位红外光谱和质谱技术、同位素示踪技术以及高通量测序方法，重点研究沉积物—水界面处氮和磷的物理、化学和生物反应过程，深入探究磷的沉积与释放规律，揭示氮迁移与转化的生物代谢机制。通过室内模拟实验和现场试验，辨识水位过程、内源负荷与生物作用之间的关系，确定三者对白洋淀水质的作用与影响，探讨营养盐在水相、泥相、气相和生物相的分配与归趋，确定生态水位升降、内源负荷增减以及生物作用强弱对白洋淀水质的影响规律，摸清生态水位、内源负荷与生物作用的适宜范围和最佳状态，提出基于水质安全保障的水位调节、内源削减与生物强化协同技术与调控方法，为白洋淀水环境保护和雄安新区可持续发展提供技术支撑，为浅水草型湖泊内源污染控制提供理论指导。

本项目针对白洋淀内源氮和磷污染的突出问题，考察了白洋淀水质和底质污染以及生物群落分布状况，确定了氮磷营养盐形态分布和沉积物—水界面环境特征，从氮磷的物理、化学和生物反应过程角度，明确了磷的沉积与释放规律，摸清了氮迁移与转化的生物代谢机制。通过模拟和现场试验，确定生态水位过程、内源负荷增减以及生物作用强弱对白洋淀水质的影响规律，提出基于水质安全保障的水位调节、内源削减与生物强化协同技术与调控方法。主要研究成果有：.（1）内源污染负荷与生物群落分布特征。白洋淀内源氮磷污染生态风险较高，不同湿地系统的综合污染程度为：苇田>府河河道>荷塘>开阔淀面>围堤围埝>农田>养殖塘。大型沉水植物生物量呈下降趋势，底栖动物耐污种增加，水生植物（芦苇、荷花）密集水域普遍高程较高，大型维管束植物显著影响湿地系统内源污染富集。.（2）内源磷在沉积相和水相的分配规律。苇田、荷塘内源磷受根系扰动而空间异质；河道、淀面内源磷相对惰性，但间隙水磷浓度高。铁的氧化还原循环主控泥水界面有效态磷的分配。风力扰动下的水位波动造成间隙水中磷释放，同时促进铁氧化重新固定磷。温度升高、酸碱增强以及缺氧均会促进内源磷释放。.（3）内源氮迁移与转化的生物代谢机制。温度上升、酸碱增强、缺氧以及水位波动均加速内源氮释放。有机物矿化促进反硝化与水生植物共同抑制内源氮释放。水陆界面硝化强度最高，反硝化和厌氧氨氧化是氮素去除主要途径，厌氧氨氧化占比10%~28%。好氧和厌氧氨氧化菌群广泛共存，多样性和丰度与ORP显著相关。.（4）白洋淀水质安全综合调控方法。科学清除围堤围埝，可有效提高淀区水动力，增加水体交换能力和水环境容量。针对不同淀区健康等级，实施分区域精准清淤，可有效恢复水体连通和改善水质。生态清淤严重破坏底栖生境，须开展人工强化与自然恢复相协调的底栖生态修复。