高原湖泊流域山地农村磷污染定量源解析及迁移转化规律研究

The rural environment protection has always been a big problem in China as its huge quantities and totally different extent of pollution. The mountainous villages which located in the southwest of China, Yunnan Province should be paid more attention as the vicinity of these villages distributed several Plateau Lakes which has very fragile eco-environment and face very high contamination risk as its feature of limitation of recharging water source and long period of changing water. Therefore, the control of mountainous rural environment pollution has become the significant part of water environment protection of Plateau Lake, and the phosphorus contamination, which is the limitation indicator of Lake Eutrophication, and its quantitative source apportionment has become a hot spot. However, there are two challenges while dealing with the phosphorus contamination problems in mountainous village as follows: (1) To quantitatively apportion the non-point source of phosphorus contamination in mountainous villages; (2) To determine the key confluence and transport process of phosphorus contamination inside the village. Thus, in order to solve the abovementioned problems, we would choose the typical mountainous villages in Puzhehei, which located in the southeast of Yunnan Province as the research objects, and carry out our research by using the combination manners of field in-situ, indoor simulation and field in-situ verification experiment and also the 32P isotope tracing method. Firstly, we would ascertain the quantitative characteristics of point (the outlets of wastewater) and non-point (solid wastes such as household refuses and excrements of livestock) source of phosphorus contamination in mountainous village. Secondly, we would deeply explore the effects of confluence ditch type and sediment micro-environment condition of the ditch on the key transport process of phosphorus contamination between the interface of water and sediment, and identify the dominant driving factors. Finally, we would precisely evaluate the phosphorus contamination environment risks of the concentrating discharge out of the village, and comprehensively obtain the influencing mechanism of the whole transport process of phosphorus in mountainous village including production from dispersive residents, transport and confluence inside the village and concentrating discharge out of the village. The research results could not only provide decision basis for the comprehensive promotion of the top-level design of wastewater treatment of mountainous village, but also provide the scientific principle for the optimization of ecological space of mountainous village and the introduction of ecological sponge to the wastewater treatment. It could also provide technical examples for the improvement of collection ditches of rural sewage and selection of treatment arts and technologies.

山地农村环境污染控制成为高原湖泊水环境保护重要组成部分，其磷污染定量源解析是国内外研究热点。但存在两方面挑战：山地农村磷污染面源定量解析；磷污染在村内汇流迁移关键过程判定。本项目以普者黑流域典型山地农村为对象，基于野外原位试验、室内模拟试验与野外原位验证相结合并采用32P同位素示踪的方法，系统得出山地农村磷污染点源（污水排放口）和面源（生活垃圾、畜禽粪便等固体废物）定量特征；深入揭示村内汇流沟渠类型（土沟、生态沟、砖砌沟）及沟渠底泥微环境条件对磷污染水-底泥界面迁移关键过程的影响并识别主要驱动因子；准确评估磷污染的出村集中排放环境风险，综合得出山地农村磷污染住户分散产生、村内汇流迁移和出村集中排放的全过程影响机制。研究成果可为全面推进山地农村污水处理顶层设计提供决策依据，为优化山地农村生态空间并将生态海绵体引入其污水处理提供科学依据，为农村污水收集沟渠改造、处理工艺技术选择等提供技术支撑。

山地农村环境污染控制是高原湖泊水环境保护重要组成部分，其磷污染定量源解析是国内外研究热点。本项目以典型高原山地农村沟渠底泥为研究对象，分析云南省典型高原山地农村沟渠底泥中氮磷形态的变化规律，同时估算底泥-上覆水界面氮磷营养盐释放通量。运用Perason相关性分析，冗余分析（RDA）等构建底泥-上覆水氮磷污染物与环境因子间的关联性，预测底泥氮磷最不利释放条件。同时，采用室内模拟方式，通过调整不同人口规模〔分别为CK、2、6、12、24 人〕排放水量以及通过外源添加设置不同类型农村磷污染程度〔依次为0、5、10、20 mg/L〕水体，探究农村沟渠污水汇流迁移过程中水体-底泥界面营养盐的迁移转化规律，评价不同人口规模及不同类型农村磷污染水体-底泥的污染程度及释放风险，以期为农村环境保护及湖泊富营养化污染防治提供理论依据与数据支撑。（1）微生物细菌在酸性和强碱条件下会促进底泥中NH4+-N向上覆水体释放，而中性条件下氮磷营养盐释放能力较弱。随时间推移，碱性条件可能会增加氮磷污染物含量，中性条件可能会降低氮磷污染物含量，而酸性条件NH4+-N含量变化起伏最大。（2）环境因子pH会影响山地农村沟渠底泥中各氮磷形态转化进而影响上覆水氮磷含量及释放通量变化，导致农村沟渠上覆水体进一步污染。（3）底泥碳、氮、磷受水体扰动释放使水体内梅罗污染指数随时间上升，并随人口规模增加先上升后降低，其中6人排放水体内梅罗污染指数最高，水体富营养化风险最大。（4）不同人口规模排放水体影响下底泥营养盐释放，底泥全磷（TP）、全氮（TN）、总有机碳（TOC）含量及单因子污染指数随人口规模增大而先减少后增多，可转化态氮磷均在一定程度上释放或累积，影响底泥营养盐的释放风险。（5）不同类型农村磷污染水体影响下水体扰动促进底泥对磷的吸附，静置及扰动水体下底泥磷含量增加。受磷污染水体影响，底泥氮及有机碳释放且随实体磷浓度的升高而增加。沟渠底泥对水体营养盐的吸附机制为不稳定的物理吸附，导致底泥对水体磷缓冲性降低且继续释放风险增加。