發(fā)布時(shí)間：2018-04-30 13:16

  本文選題：澎溪河回水區(qū) + 沉積物��； 參考：《西南大學(xué)》2017年碩士論文

【摘要】：自2003年三峽水庫正式蓄水以來,由于庫區(qū)內(nèi)水位抬升引起水體流速減緩,支流回水區(qū)由于水體滯留時(shí)間的延長和營養(yǎng)因子的蓄積,水華爆發(fā)情況尤其嚴(yán)重。水華爆發(fā)的主要原因是水體中營養(yǎng)過剩,而水體營養(yǎng)主要有2個(gè)來源:包括河岸陸地等外源和水體內(nèi)源。有關(guān)三峽庫區(qū)陸地面源和點(diǎn)源污染與庫區(qū)支流水華關(guān)系的研究已有不少,但有關(guān)支流底泥等內(nèi)源沉積物對(duì)水華貢獻(xiàn)的研究較為少見。沉積物作為水體內(nèi)源營養(yǎng)物質(zhì)的來源,對(duì)水體富營養(yǎng)化現(xiàn)象的維持起著至關(guān)重要的作用,而微生物作為物質(zhì)循環(huán)和能量流動(dòng)的重要組成部分,在水-沉積物間物質(zhì)循環(huán)的過程中發(fā)揮著重要作用,影響著藻類植物的生長和水華的形成。本研究以三峽水庫北岸最大一級(jí)支流澎溪河的回水區(qū)—高陽平湖為對(duì)象,于2016年1月至2017年1月進(jìn)行了野外長期定點(diǎn)監(jiān)測(cè),分析了回水區(qū)藻類植物群落結(jié)構(gòu)的季節(jié)變化特征,水華不同時(shí)期上覆水-沉積物間理化性質(zhì)、沉積物中微生物群落結(jié)構(gòu)及生物酶活性變化,探討沉積物中微生物種群與內(nèi)源營養(yǎng)物質(zhì)循環(huán)及水華爆發(fā)的關(guān)系,為三峽庫區(qū)支流回水區(qū)水華的防控、治理提供一定理論依據(jù)。研究具體結(jié)果如下:(1)于2016年3月~2017年1月對(duì)澎溪河回水區(qū)水體浮游植物群落組成及演替規(guī)律進(jìn)行研究。結(jié)果顯示,四季水體樣品中共檢出藻類植物7門117種(包括變種),藻類群落組成季節(jié)差異明顯。春季水華爆發(fā)時(shí)期僅藻類檢出5門32種,主要優(yōu)勢(shì)藻為藍(lán)藻門小型色球藻(Chroococcus minor)、尖細(xì)顫藻(Oscillatoria acuminata)、湖泊鞘絲藻(Lyngbya limnelica)、綠藻門小球藻(Chlorella vulgaris),此時(shí)藻類群落結(jié)構(gòu)單一。隨季節(jié)交替,秋季藻類增加至7門82種,優(yōu)勢(shì)藻逐漸演替為硅藻門針桿藻(Synedra sp.)、隱藻門尖尾藍(lán)隱藻(Chroomonas acuta)。(2)監(jiān)測(cè)期間,澎溪河回水區(qū)4個(gè)采樣斷面藻類生物量與葉綠素a(Chla)含量的季節(jié)變化同步,與藻類細(xì)胞密度季節(jié)變化趨勢(shì)稍有差異。藍(lán)藻、隱藻和硅藻是該回水區(qū)的主要藻類,其中硅藻主要出現(xiàn)在秋、冬季,綠藻在各個(gè)斷面均有檢出,但細(xì)胞密度占比不大,藍(lán)藻、隱藻種類數(shù)少于綠藻但細(xì)胞密度水平較高,峰值分別為48.89×106 cell/L、1.61×106 cell/L,屬于澎溪河回水區(qū)的優(yōu)勢(shì)藻種。研究期間藻類集群演替情況大致為:藍(lán)藻、甲藻→綠藻→隱藻、硅藻。(3)2016年1月~2016年7月,對(duì)澎溪河回水區(qū)水華不同時(shí)期上覆水(水面下0.5m)、沉積物環(huán)境因子的變化進(jìn)行跟蹤監(jiān)測(cè)。結(jié)果顯示:上覆水pH隨水華發(fā)生顯著升高(p0.05),溶解氧含量在水華前及水華初期顯著上升,總氮(TN)、總磷(TP)、溶解性總氮(DTN)、溶解性總磷(DTP)、硝態(tài)氮(NO3--N)、正磷酸鹽(PO43--P)含量在水華前期顯著上升,并隨水華持續(xù)發(fā)生明顯下降,溶解性磷是上覆水中磷元素主要存在形式,約占51.9%~74.4%;硝化作用是上覆水硝態(tài)氮的來源之一。沉積物中總氮、總磷和硝態(tài)氮含量在3月水華形成期明顯下降,但隨水華持續(xù)發(fā)生顯著升高;其含量分別是上覆水對(duì)應(yīng)營養(yǎng)因子的401.9~515.8、5062.5~5675.7和58.5~89.2倍,體現(xiàn)出沉積物作為水體內(nèi)源磷庫的重要作用,沉積物中內(nèi)源營養(yǎng)在水華發(fā)生前釋放進(jìn)入水體,是上覆水氮、磷營養(yǎng)的主要來源。(4)在水華發(fā)生不同時(shí)期,水體富營養(yǎng)化限制因子仍為磷元素。沉積物磷主要以無機(jī)磷形式存在,其含量為0.40~0.54 g/kg,占沉積物總磷的66.7%~95.2%。各形態(tài)磷含量變化:鐵鋁結(jié)合態(tài)磷(NaOH-P)鈣結(jié)合態(tài)磷(HCl-P)氧化還原形磷(BD-P)松散結(jié)合態(tài)磷(NH4Cl-P),無機(jī)磷組成以鐵鋁結(jié)合態(tài)磷(NaOH-P)為主。水華發(fā)生前沉積物HCl-P、NaOH-P含量明顯下降(分別降低28.5%、5.6%),隨水華的持續(xù)發(fā)生,其含量穩(wěn)定上升,BD-P含量在3~5月持續(xù)下降。沉積物TP、NaOH-P、NH4Cl-P與上覆水營養(yǎng)因子呈極顯著正相關(guān)關(guān)系(p0.01),對(duì)水-沉積物界面間物質(zhì)循環(huán)及水體富營養(yǎng)化的維持起到重要作用。(5)與1月樣品相比,沉積物中微生物磷脂脂肪酸(PLFAs)含量在水華形成期及水華發(fā)生初期明顯升高(分別為76.0%、151.8%),隨水華現(xiàn)象的持續(xù)明顯降低至6月水華消逝期緩慢回升,較5月上升了14.1%。此外,隨水華發(fā)生,沉積物中個(gè)別種類細(xì)菌豐度明顯上升占據(jù)優(yōu)勢(shì),導(dǎo)致沉積物細(xì)菌類群組成與相對(duì)比例發(fā)生明顯改變,細(xì)菌群落多樣性和均勻度明顯下降,相比1月,5月水華持續(xù)期多樣性及均勻度指數(shù)分別下降49.6%、24.0%。沉積物中堿性磷酸酶(APA)活性在水華發(fā)生前顯著提高(p0.05),隨水華持續(xù)爆發(fā)其活性受到抑制。(6)冗余分析(RDA)的結(jié)果表明,水華爆發(fā)前期,澎溪河回水區(qū)主要為藍(lán)-綠藻型水體,此后水體有向綠-硅藻轉(zhuǎn)化的趨勢(shì);沉積物中微生物PLFAs與TP相關(guān)性較大,沉積物中APA、PLFAs和TP的含量是澎溪河回水區(qū)水華發(fā)生的主導(dǎo)因子。此外,NH4Cl-P、BD-P分別在水華形成初期和水華消逝后對(duì)藻類生長有較大影響。
[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.

【學(xué)位授予單位】：西南大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：X524;Q178

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