澎溪河回水区沉积物微生物群落、内源营养释放及水华爆发的相关性研究

发布时间：2018-04-30 13:16

本文选题：澎溪河回水区 + 沉积物　；参考：《西南大学》2017年硕士论文

【摘要】：自2003年三峡水库正式蓄水以来,由于库区内水位抬升引起水体流速减缓,支流回水区由于水体滞留时间的延长和营养因子的蓄积,水华爆发情况尤其严重。水华爆发的主要原因是水体中营养过剩,而水体营养主要有2个来源:包括河岸陆地等外源和水体内源。有关三峡库区陆地面源和点源污染与库区支流水华关系的研究已有不少,但有关支流底泥等内源沉积物对水华贡献的研究较为少见。沉积物作为水体内源营养物质的来源,对水体富营养化现象的维持起着至关重要的作用,而微生物作为物质循环和能量流动的重要组成部分,在水-沉积物间物质循环的过程中发挥着重要作用,影响着藻类植物的生长和水华的形成。本研究以三峡水库北岸最大一级支流澎溪河的回水区—高阳平湖为对象,于2016年1月至2017年1月进行了野外长期定点监测,分析了回水区藻类植物群落结构的季节变化特征,水华不同时期上覆水-沉积物间理化性质、沉积物中微生物群落结构及生物酶活性变化,探讨沉积物中微生物种群与内源营养物质循环及水华爆发的关系,为三峡库区支流回水区水华的防控、治理提供一定理论依据。研究具体结果如下:(1)于2016年3月~2017年1月对澎溪河回水区水体浮游植物群落组成及演替规律进行研究。结果显示,四季水体样品中共检出藻类植物7门117种(包括变种),藻类群落组成季节差异明显。春季水华爆发时期仅藻类检出5门32种,主要优势藻为蓝藻门小型色球藻(Chroococcus minor)、尖细颤藻(Oscillatoria acuminata)、湖泊鞘丝藻(Lyngbya limnelica)、绿藻门小球藻(Chlorella vulgaris),此时藻类群落结构单一。随季节交替,秋季藻类增加至7门82种,优势藻逐渐演替为硅藻门针杆藻(Synedra sp.)、隐藻门尖尾蓝隐藻(Chroomonas acuta)。(2)监测期间,澎溪河回水区4个采样断面藻类生物量与叶绿素a(Chla)含量的季节变化同步,与藻类细胞密度季节变化趋势稍有差异。蓝藻、隐藻和硅藻是该回水区的主要藻类,其中硅藻主要出现在秋、冬季,绿藻在各个断面均有检出,但细胞密度占比不大,蓝藻、隐藻种类数少于绿藻但细胞密度水平较高,峰值分别为48.89×106 cell/L、1.61×106 cell/L,属于澎溪河回水区的优势藻种。研究期间藻类集群演替情况大致为:蓝藻、甲藻→绿藻→隐藻、硅藻。(3)2016年1月~2016年7月,对澎溪河回水区水华不同时期上覆水(水面下0.5m)、沉积物环境因子的变化进行跟踪监测。结果显示:上覆水pH随水华发生显著升高(p0.05),溶解氧含量在水华前及水华初期显著上升,总氮(TN)、总磷(TP)、溶解性总氮(DTN)、溶解性总磷(DTP)、硝态氮(NO3--N)、正磷酸盐(PO43--P)含量在水华前期显著上升,并随水华持续发生明显下降,溶解性磷是上覆水中磷元素主要存在形式,约占51.9%~74.4%;硝化作用是上覆水硝态氮的来源之一。沉积物中总氮、总磷和硝态氮含量在3月水华形成期明显下降,但随水华持续发生显著升高;其含量分别是上覆水对应营养因子的401.9~515.8、5062.5~5675.7和58.5~89.2倍,体现出沉积物作为水体内源磷库的重要作用,沉积物中内源营养在水华发生前释放进入水体,是上覆水氮、磷营养的主要来源。(4)在水华发生不同时期,水体富营养化限制因子仍为磷元素。沉积物磷主要以无机磷形式存在,其含量为0.40~0.54 g/kg,占沉积物总磷的66.7%~95.2%。各形态磷含量变化:铁铝结合态磷(NaOH-P)钙结合态磷(HCl-P)氧化还原形磷(BD-P)松散结合态磷(NH4Cl-P),无机磷组成以铁铝结合态磷(NaOH-P)为主。水华发生前沉积物HCl-P、NaOH-P含量明显下降(分别降低28.5%、5.6%),随水华的持续发生,其含量稳定上升,BD-P含量在3~5月持续下降。沉积物TP、NaOH-P、NH4Cl-P与上覆水营养因子呈极显著正相关关系(p0.01),对水-沉积物界面间物质循环及水体富营养化的维持起到重要作用。(5)与1月样品相比,沉积物中微生物磷脂脂肪酸(PLFAs)含量在水华形成期及水华发生初期明显升高(分别为76.0%、151.8%),随水华现象的持续明显降低至6月水华消逝期缓慢回升,较5月上升了14.1%。此外,随水华发生,沉积物中个别种类细菌丰度明显上升占据优势,导致沉积物细菌类群组成与相对比例发生明显改变,细菌群落多样性和均匀度明显下降,相比1月,5月水华持续期多样性及均匀度指数分别下降49.6%、24.0%。沉积物中碱性磷酸酶(APA)活性在水华发生前显著提高(p0.05),随水华持续爆发其活性受到抑制。(6)冗余分析(RDA)的结果表明,水华爆发前期,澎溪河回水区主要为蓝-绿藻型水体,此后水体有向绿-硅藻转化的趋势;沉积物中微生物PLFAs与TP相关性较大,沉积物中APA、PLFAs和TP的含量是澎溪河回水区水华发生的主导因子。此外,NH4Cl-P、BD-P分别在水华形成初期和水华消逝后对藻类生长有较大影响。
[Abstract]:Since the formal storage of the Three Gorges Reservoir in 2003, the flow rate of water is slowed down due to the rise of water level in the reservoir area. The outbreak of water bloom is especially serious because of the extension of water retention time and the accumulation of nutrient factors in the backwater area of the tributary. The main reason for the outbreak of water bloom is the overnutrition in the water body, and there are 2 main sources of water nutrition, including the shore land. There are many studies on the land surface source and point source pollution in the Three Gorges Reservoir area and the relationship between the tributary water bloom in the reservoir area and the water bloom. However, the research on the contribution of the inner source sediments to the water bloom is rare. As the source of the nutrients in the water body, the sediment is critical to the maintenance of the eutrophication in the water body. As an important part of the circulation of material and energy flow, microorganism plays an important role in the process of material circulation between water and sediment, which affects the growth of algae and the formation of water bloom. This study is based on the return area of the Pengxi River, the largest tributary of the Three Gorges reservoir, Pinghu, in 2016, 1 From month to January 2017, long term site monitoring was carried out in the field. The seasonal variation characteristics of algae plant community structure in the backwater area, the physical and chemical properties of overlying water and sediment in different periods of water bloom, the microbial community structure and biological enzyme activity in the sediment, and the circulation of microbiological population and endogenous nutrients in the sediment and the water bloom in the sediments were discussed. The relation of hair supply provides a certain theoretical basis for control and control of water bloom in the backwater area of the Three Gorges Reservoir area. The specific results are as follows: (1) the composition and succession law of phytoplankton community in the water body of the Pengxi River Basin were studied in January, March 2016. The results showed that 117 species of algae plants were detected in the four seasons water samples (including the change of the algae). The seasonal difference of algae community composition is obvious. Only 5 doors and 32 species of algae were detected in spring blooms, the main dominant algae were Chroococcus minor, Oscillatoria acuminata, Lyngbya limnelica, and Chlorella (Chlorella vulgaris) of green algae (Chlorella vulgaris), and the structure of algae was single. In autumn, the algae increased to 82 species in 7 gates, and the Dominant Algae gradually succesed to Synedra sp. and Chroomonas acuta. (2) during the monitoring, the algae biomass of the Pengxi River backwater area was synchronized with the seasonal variation of chlorophyll a (Chla) content and the seasonal variation trend of algae cell density. Cyanobacteria, cryptoalgae and diatom are the main algae in the backwater area. Diatom mainly appears in autumn, winter, and green algae in all sections, but the density of cell density is not large. The number of cyanobacteria, saphenous algae is less than green algae, but the cell density level is higher, the peak value is 48.89 x 106 cell/L, 1.61 x 106 cell/L, which belong to the Pengxi River backwater area. The succession of algal species during the study period was roughly as follows: cyanobacteria, dinoflagellate, green algae, cryptoalgae, diatom. (3) in July ~2016 January 2016, the changes of overlying water (under water 0.5m) in the different period of water bloom in the Pengxi River Basin were monitored and monitored. The results showed that the overlying water pH increased significantly with water bloom (P0.05). The content of dissolved oxygen increased significantly in the early stage of water bloom and in the early stage of bloom. Total nitrogen (TN), total phosphorus (TP), dissolved total nitrogen (DTN), dissolved total phosphorus (DTP), nitrate nitrogen (NO3--N), and orthophosphate (PO43--P) increased significantly in the early stage of bloom, and decreased with water bloom, and dissolved phosphorus was the main form of phosphorus in the overlying water, accounting for about 51.9%~74. .4%, nitrification is one of the sources of nitrate nitrogen in overlying water. The content of total nitrogen, total phosphorus and nitrate nitrogen in the sediment decreased significantly in the formation period of water bloom in March, but it increased significantly with water bloom in the water bloom in March. The content of the content is 401.9~515.85062.5~5675.7 and 58.5 ~89.2 times of the overlying water corresponding to the nutrient factors, which reflect the sediment as the endogenous phosphorus pool of the water body. The essential nutrition of the sediments is released into the water body before the occurrence of water bloom. It is the main source of overlying water nitrogen and phosphorus nutrition. (4) in different periods of water bloom, the limiting factor of eutrophication is still phosphorus. The phosphorus in the sediment mainly exists in the form of inorganic phosphorus, and its content is 0.40~0.54 g/kg, accounting for 66.7%~95.2%. of the total phosphorus. The changes of phosphorus content in each form: Fe Al bound phosphorus (NaOH-P) calcium bound phosphorus (HCl-P) oxidation-reduction form phosphorus (BD-P) loosely bound phosphorus (NH4Cl-P), inorganic phosphorus composition with Fe Al bound phosphorus (NaOH-P). The content of HCl-P in the sediments before water bloom decreased significantly (28.5%, 5.6% respectively), with the continuous occurrence of water bloom, its content was stable. The content of BD-P decreased continuously in 3~5 months. The sediment TP, NaOH-P, NH4Cl-P and overlying water nutrition factor had a very significant positive correlation (P0.01), which played an important role in the material circulation and the maintenance of eutrophication between the water sediment interface. (5) the content of microbial phospholipid fatty acid (PLFAs) in the sediments was formed in the formation period of the water bloom compared with the samples in January. And the early rise of water bloom (76%, 151.8%, respectively), with the continuous decrease of blooms in June, a slow rise in the vanishing period of water bloom in June, a rise of 14.1%. from May, with the occurrence of water bloom, a distinct increase in the abundance of individual species of bacteria in the sediments, and a significant change in the composition and relative proportion of the bacteria in the sediments. The diversity and evenness of bacterial community decreased obviously. The diversity and evenness index of water bloom in January, May, and evenness index decreased by 49.6%. The activity of alkaline phosphatase (APA) in 24.0%. sediments increased significantly (P0.05) before water bloom, and its activity was inhibited with the continuous eruption of water bloom. (6) the results of redundancy analysis (RDA) showed that water bloom erupted. In the earlier period, the backwater area of the Pengxi River is mainly blue green algae type water body, and then the water body has the tendency to convert to green diatom. The microorganism PLFAs and TP in the sediments are related greatly. The content of APA, PLFAs and TP in the sediments is the dominant factor in the bloom of the Pengxi River backwater. In addition, NH4Cl-P and BD-P are respectively in the early stage of the formation of water bloom and after the vanishing of water bloom. The growth of the class has a great influence.

【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;Q178

【参考文献】