三峡库区澎溪河高阳平湖水环境及内源磷释放关系研究

发布时间：2018-05-19 16:10

本文选题：澎溪河高阳平湖 + 富营养化　；参考：《西南大学》2017年硕士论文

【摘要】：三峡水库蓄水以来,由原始的河流生态系统转变为水库型生态系统,水体的水文、水动力和水质特征均发生巨大的变化,部分支流水华频繁爆发。而近年来澎溪河较其他支流爆发更为严重的水体富营养化和水华现象,引起了社会各界的关注。已有研究表明,水体的分层以及水文条件被认为是水华形成的关键因素,氮磷营养则是作为水体藻类生长的限制性因素,而作为蓄水仅14年的三峡库区,由于冬夏季30米的调水落差,支流底泥与消落带在一年中经历着剧烈变化,在库区水环境中充当着“源”和“汇”的重要功能。因此,本研究以北岸最大支流澎溪河中游高阳平湖为例,在研究水体藻类生长繁殖与水体水质、水文的关系的基础上,分析底泥总磷和磷形态与水体营养的关系,以阐明底泥生物化学过程与支流水环境的关系。本文于2016年1月至10月对澎溪河高阳平湖水体和底泥进行采样分析,得出的结果如下:(1)本研究将水体分层分为温跃层+滞温层模式,混合层不明显,水体中叶绿素-a(Chl-a)主要存在于0~10m深度的温跃层,温跃层水体仍然是藻类生长富集的重要区域,水体分层是水华暴发的重要限制性因素。(2)高阳平湖全年水体总氮(TN)、总磷(TP)含量(均值)1.793 mg·L-1、0.062 mg·L-1,远超水体发生富营养化的阈值,冬季、春季、秋季主要以溶解性氮、磷为主,占TN、TP的72.34%、84.4%,夏季水体水体以颗粒态为主。有10.41%样品的TN/TP值22(质量比,下同);有56.25%样品处于22TN/TP32,有33.34%样品的TN/TP≥32,澎溪河高阳平湖处于磷限制状态,磷仍是水体富营养化和水华暴发的重要限制性因子。(3)高阳平湖底泥中TP含量变化范围为0.49~0.66 g·kg-1,均值为0.59 g·kg-1,总磷含量与长江中下游干流及其湖泊沉积物相比处于中下游水平。底泥TP含量随季节呈现:春季冬季夏季秋季,可初步得出,春季底泥为水体磷的“源”,而夏秋冬三季为水体磷的“汇”。底泥中松散态磷(NH4Cl-P)、氧化还原敏感态磷(BD-P)、金属氧化物结合态磷(NaOH-P)、钙结合态磷(HCl-P)、残渣磷(Res-P)分别占TP的0.24%、2.08%、71.81%、9.01%和16.85%,底泥中以无机磷为主,达到83.15%,有机磷含量处于较低水平,同时可知底泥中磷形态主要以NaOH-P为主,存在有潜在的磷污染风险。(4)Chl-a与底泥中NH4Cl-P表现出显著的正相关(p0.05),与HCl-P表现出显著的负相关(p0.05),水体TN对底泥中磷的形态分布无显著的作用。而水体TP与生物有效性磷(BAP)、NaOH-P和HCl-P呈现极显著负相关关系(p0.01),即底泥中BAP、NaOH-P和HCl-P的释放对水体TP的增加有重要的贡献。(5)底泥pH、含水率、容重、有机质(TOC)、TN与底泥磷的形态并无显著的相关关系,这些环境因子对高阳平湖底泥磷形态分布以及吸附、释放作用较小;然而氧化还原电位(Eh)与TP呈现极显著的负相关关系(p0.01),Eh值对底泥磷的释放具有重要作用,是众多环境因子之中影响底泥磷形态与分布的重要因素。底泥中易被利用磷形态的变化趋势与PLFAs、APA变化一致,这说明微生物对于底泥磷的形态分布以及吸附、释放具有重要作用。
[Abstract]:Since the storage of the Three Gorges reservoir, the original river ecosystem has been transformed into a reservoir type ecosystem. The hydrological, hydrodynamic and water quality characteristics of the water body have been changed greatly. Some branches of water bloom frequently erupt. In recent years, the Pengxi River has been more serious than other tributaries in water eutrophication and water bloom, causing the social circles. Attention. Studies have shown that the stratification and hydrological conditions of water are considered as the key factors for the formation of water bloom. Nitrogen and phosphorus nutrition is a limiting factor for the growth of algae in water bodies. As a reservoir area of only 14 years of water storage, the bottom mud and the falling zone of tributaries have undergone dramatic changes in the reservoir for a year of 30 meters in winter and summer. This study takes Pinghu, the middle reaches of Pengxi River, the largest tributary of the north bank as an example. On the basis of studying the relationship between the growth and reproduction of algae and water quality and hydrology, the relationship between the morphology of total phosphorus and phosphorus in the sediment and the water body nutrition is analyzed in order to clarify the biochemical process of the sediment. From January 2016 to October, the water and sediment of Pinghu, Gaoyang River in Pengxi River are sampled and analyzed. The results are as follows: (1) this study divides the water layer into a thermocline + stagnant layer model, and the mixed layer is not obvious. The chlorophyll -a (Chl-a) in the water body is mainly in the thermocline in the depth of 0~10m, and the thermocline is still in the water body. It is an important area for algae growth and enrichment, and the stratification of water body is an important limiting factor for the outbreak of water bloom. (2) the total nitrogen (TN) and total phosphorus (TP) content (mean) of Gao Yang in Pinghu is 1.793 mg. L-1,0.062 mg. L-1 in the whole year. In winter, in spring and in autumn, mainly dissolved nitrogen and phosphorus, accounting for TN, 72.34%, 84.4% of TP, In summer, the main body of water body is particle state. There are 10.41% samples with TN/TP value 22 (mass ratio, the same below); 56.25% samples are in 22TN/TP32, 33.34% samples are TN/TP more than 32, the Pengxi River Gaoyang Pinghu is in the restricted state of phosphorus. Phosphorus is still an important limiting factor for the eutrophication of water body and the outbreak of water bloom. (3) the change range of the content of TP in the sediment of Gaoyang The mean value of 0.49~0.66 g / kg-1 is 0.59 G. Kg-1. The content of total phosphorus is in the middle and lower reaches of the middle and lower reaches of the Yangtze River and its lake sediments. The content of sediment TP is shown in the season: in spring and winter in summer and autumn, the sediment in spring is the "source" of phosphorus in the water body, while the three season in summer, autumn and winter is the "sink" of phosphorus in the water body. Phosphorus (NH4Cl-P), redox sensitive phosphorus (BD-P), metal oxide bound phosphorus (NaOH-P), calcium bound phosphorus (HCl-P) and residue phosphorus (Res-P) accounted for 0.24%, 2.08%, 71.81%, 9.01% and 16.85% of TP, respectively, and the content of organophosphorus was 83.15%, and the content of organophosphorus was at a low level. At the same time, the phosphorus form in the sediment was mainly NaOH-P. There was a potential risk of phosphorus pollution. (4) Chl-a showed significant positive correlation with NH4Cl-P in sediment (P0.05), and showed significant negative correlation with HCl-P (P0.05). Water TN had no significant effect on the distribution of phosphorus in sediment, while TP in water body and bioavailable phosphorus (BAP), NaOH-P and HCl-P showed significant negative correlation (P0.01), that is BAP in sediment. The release of NaOH-P and HCl-P has an important contribution to the increase of TP in the water body. (5) the sediment pH, water content, bulk density, organic matter (TOC), and TN have no significant correlation with the form of phosphorus in the sediment. These environmental factors have little use on the phosphorus form distribution and the adsorption and release of phosphorus in the bottom mud of Pinghu, but the oxidation-reduction potential (Eh) and TP are extremely negative. The correlation (P0.01), Eh value plays an important role in the release of phosphorus in sediment. It is an important factor affecting the form and distribution of phosphorus in sediment among many environmental factors. The change trend of the form of phosphorus in the sediment is consistent with the changes of PLFAs and APA. This shows that microbes have an important role in the distribution of phosphorus in the sediment and the adsorption and release of phosphorus.
【学位授予单位】：西南大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X524

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