研究生知识库

近20 年来，我国湖泊富营养化形势日益严峻，水质明显恶化，严重危及饮用水安全。大量研究表明，过多的氮、磷输入是导致湖泊水体富营养化的主要原因。而在大多数湖泊中，磷是控制富营养化的关键因子。因此，控磷一直是湖泊富营养化研究和治理的焦点。虽然沉积物有机磷是伴随着有机质降解而活化迁移的，但很早就有研究发现在有机质降解过程中，碳、磷的释放行为存在明显差异。尽管海洋沉积物有机质降解过程的碳、磷地球化学行为差异早已引起学者们广泛关注，研究发现缺氧条件下海洋沉积物有机质降解优先释放磷（相对碳而言）。但与此形成鲜明对照的是，迄今少见关于湖泊沉积物有机质降解过程有机碳、有机磷活化迁移行为差异的系统研究报道。本项研究拟选取贵州乌江流域的平寨水库、普定水库和红枫湖水库三个典型的营养状态不同的水体季节性热分层深水湖泊作为研究对象，率先系统开展不同营养状况湖泊水体颗粒态有机碳（POC）、有机磷（POP）含量及其比值以及沉积物柱芯有机碳（Corg）、有机磷（Porg）含量及其比值的系统研究，阐明湖泊有机质降解过程中磷和碳的释放行为差异。研究发现：（1）在营养状态不同的湖泊，颗粒物沉降过程中POC和POP在垂向剖面的含量变化存在显著差异，POC在沉降过程中因降解释放含量不断减少，而POP（SMT法）在中下层水体具有显著的含量增加趋势。POP在中下层水体的显著增加可能是由于PO4向poly-P的大量转化。红枫湖水库沉积物磷负荷较高，因此湖泊颗粒物在沉降过程中POP的增加趋势也较显著。（2）处于建库初期的平寨水库，有机碳、磷的埋藏量相对较低；普定水库的有机碳、磷埋藏量一直处于较高水平；而红枫湖的沉积物历史剖面反映了建库后至今，随着水体富营养化的发生，有机碳、磷的埋藏量显著升高，富营养化的红枫湖具有最高的有机碳、磷埋藏量。但是沉积物中有机磷占总磷的比例的变化趋势正好相反。营养程度越高的湖泊，沉积物中有机磷所占的比例越低，反映出其有机磷活化效率越高。（3）红枫湖表层沉积物Corg:Porg比值较建库初期沉积物Corg:Porg比值显著升高，反映出有机质降解过程中P较C释放的速率增大；而在营养水平较低的平寨水库和普定水库，其变化特征不明显。湖泊富营养化导致底部水体缺氧可能是导致有机质降解过程中磷较碳释放速率增大的主要因素。

In the past 20 years, the eutrophication of lakes in China has become increasingly severe, and water quality has deteriorated significantly, seriously endangering the safety of drinking water. Numerous studies have shown that excessive nitrogen and phosphorus input are the main reasons leading to eutrophication of lake waters. In most lakes, phosphorus is a key factor in controlling eutrophication. Therefore, phosphorus control has always been the focus of research and governance of lake eutrophication. Although the sediment organic phosphorus is activated and migrated along with the degradation of organic matter, it has long been found that there are significant differences in the release behavior of carbon and phosphorus during the degradation of organic matter. Although the differences in the geochemical behaviors of carbon and phosphorus in the process of organic matter degradation in marine sediments have long attracted widespread attention, the researchers found that the degradation of organic matter in marine sediments under preferential oxygen conditions preferentially releases phosphorus (relative to carbon). However, in stark contrast to this, systematic research reports on the differences in the activation and migration behaviors of organic carbon and organic phosphorus in the degradation of organic matter in lake sediments have been reported so far. Under the different oxygen and nutrient conditions of the overlying water, whether there is a significant difference in the release of phosphorus and carbon during the degradation of organic matter in lake sediments continues to be discovered.This study intends to select three typical deep-water lakes with different nutrient status of Pingzhai Reservoir, Puding Reservoir and Hongfenghu Reservoir in Guizhou Wujiang River Basin as the research object, and take the lead in systematically carrying out different nutritional status. The comparative study of particulate organic matter Corg: Porg ratio and sediment core organic carbon, organic phosphorus profile and Corg:Porg ratio in lake waters, clarifying the difference in phosphorus and carbon release behavior during the degradation of organic matter in lake sediments. In the above, the sediment trap is used to collect the sedimentary particulate matter and study the organic carbon, the deposition rate of organic phosphorus, the analysis of the changes of the organic carbon and organic phosphorus in the sediment, and the comparative study of different oxygen conditions. Sediment organic carbon, organic phosphorus burial rate (burial rate). The study found:(1) In the lakes with different vegetative status, there are significant differences in the content of POC and POP in the vertical profile during the sedimentation of particulate matter. The content of POC is reduced due to the degradation during the sedimentation process, while POP (SMT method) is obvious in the middle and lower water bodies. The increasing content of POP in the middle and lower water bodies is due to the large conversion of PO4 to polyphosphate. The Hongfenghu Reservoir have higher sediment phosphorus load, so the POP of lake particles has a more significant increase trend during sedimentation.(2) The Pingzhai Reservoir in the early stage of the construction of the reservoir has relatively low burial of organic carbon and phosphorus; the organic carbon and phosphorus burial of the Puding Reservoir has been at a relatively high level; and the sedimentary historical profile of Hongfeng Lake reflects Since the establishment of the reservoir, with the occurrence of eutrophication of water, the burial of organic carbon and phosphorus has increased significantly, and the eutrophic Hongfeng Lake has the highest organic carbon and phosphorus burial. However, the trend of the proportion of organic phosphorus in total phosphorus in sediments is reversed. The higher the nutrient level, the lower the proportion of organic phosphorus in sediments, reflecting the higher activation efficiency of organic phosphorus.(3) The ratio of Corg/Porg in the surface sediments of Hongfeng Lake reservoir is significantly higher than that in the early stage of construction. It reflects that the rate of release of P from C is increased during the degradation of organic matter, while the level of P is lower. The characteristics of the Pingzhai reservoir and Puding Reservoir are not obvious. The eutrophication of lakes leads to the lack of oxygen in the bottom water, which may be the main factor leading to the increase of phosphorus release rate during the degradation of organic matter.