本文選題：東洞庭湖　切入點(diǎn)：洲灘濕地　出處：《中國環(huán)境科學(xué)研究院》2017年碩士論文　論文類型：學(xué)位論文

【摘要】：湖泊的洲灘濕地由于季節(jié)性水位變化,處于淹沒和出露交替(干濕交替)的狀態(tài),進(jìn)而影響沉積物和上覆水中氮的形態(tài)分布,從而影響湖泊的水質(zhì)和營養(yǎng)狀態(tài)。為探究干濕交替影響下洲灘濕地沉積物-水界面各個(gè)形態(tài)氮的變化規(guī)律,識(shí)別干濕交替區(qū)域氮素營養(yǎng)的遷移轉(zhuǎn)化主要影響因素,為湖泊的區(qū)域保護(hù)提供理論依據(jù),本文選取了洞庭湖受人類活動(dòng)影響較小的東洞庭湖洲灘濕地作為研究區(qū)域,對枯水期、平水期各研究區(qū)域從陸域到水域(岸上點(diǎn)位、交界處點(diǎn)位、水下點(diǎn)位)的洲灘濕地沉積物進(jìn)行了采樣調(diào)查。通過對洲灘濕地氮形態(tài)等指標(biāo)進(jìn)行分析后,得到了洞庭湖洲灘濕地沉積物的基本性質(zhì),并對洞庭湖洲灘濕地沉積物中氮形態(tài)在干濕交替驅(qū)動(dòng)下的變化情況有了初步推斷;在此基礎(chǔ)上通過室內(nèi)模擬實(shí)驗(yàn),探尋沉積物-水界面中氮形態(tài)在水位變化下的遷移轉(zhuǎn)化規(guī)律。通過對洲灘濕地沉積物的野外實(shí)地調(diào)查研究結(jié)果表明,枯水期洲灘濕地沉積物中總氮的平均值為0.920g/kg,變異系數(shù)為0.335;硝氮的平均值為1.379mg/kg,變異系數(shù)為1.036;氨氮平均值為10.506mg/kg,變異系數(shù)為0.861。在平水期洲灘濕地沉積物中總氮的平均值為1.084g/kg,變異系數(shù)為0.230;硝氮的平均值為3.141mg/kg,變異系數(shù)為1.797;氨氮平均值為15.397mg/kg,變異系數(shù)為0.843。平水期總氮、硝氮及氨氮的平均值和枯水期相比都有所增大,除了硝氮的變異系數(shù)顯著增大外,總氮、氨氮的變異系數(shù)都有不同程度地減小。分別對枯水期和平水期的各變量作Pearson相關(guān)性分析,在枯水期,含水率與粉粒呈顯著正相關(guān)(r=0.296,p0.05),在平水期,含水率與黏粒呈極顯著負(fù)相關(guān)(r=-0.466,p0.01)。表明在枯水期時(shí),沉積物中水分主要與粉粒結(jié)合,在平水期時(shí),沉積物含水率越高越容易造成黏粒的流失。含水率在平水期與氨氮呈正相關(guān),與硝氮呈負(fù)相關(guān),在枯水期時(shí),含水率與這些變量均沒有顯著相關(guān)性。這表明含水率對氮形態(tài)的影響在不同水期是不同的。在兩個(gè)水期中總氮與硝氮均顯著正相關(guān)(r=0.420,p0.05;r=0.389,p0.05)。在枯水期時(shí),總氮與黏粒、粉粒呈正相關(guān),與砂粒呈負(fù)相關(guān);在平水期時(shí),總氮與黏粒呈正相關(guān)。表明總氮尤其是有機(jī)氮主要賦存在黏粉粒中。以覆水狀態(tài)對樣品進(jìn)行分組,分為岸上樣品和水下樣品兩組,進(jìn)行非參數(shù)檢驗(yàn)發(fā)現(xiàn),在枯水期時(shí)含水率、氨氮、總氮均有極顯著的差異性,而在平水期時(shí)含水率、硝氮有著極顯著的差異性。不同水情下的覆水狀態(tài)對沉積物中氮形態(tài)的影響不同,平水期沉積物的生物活性較強(qiáng),有助于氮的形態(tài)轉(zhuǎn)化,平水期的總氮、硝氮、氨氮等指標(biāo)的平均值都大于枯水期。覆水后沉積物中總氮、氨氮的變異系數(shù)減小,空間差異性縮小;但覆水后沉積物中硝氮的變異系數(shù)增大,空間差異性增大。室內(nèi)模擬在不同水位變化速率下,沉積物中氮形態(tài)的遷移轉(zhuǎn)化,模擬的水位變化速率分別為8cm/d、2.6cm/d及1.3cm/d(A-5、A-15及A-30)。模擬結(jié)果表明:沉積物在經(jīng)歷出露期再覆水后,上覆水中的無機(jī)氮在第一周會(huì)迅速增大,然后開始緩慢下降;在模擬的水位變化速率下,上覆水中的氮素均以硝態(tài)氮為主,所占比例從大到小依次為硝氮氨氮亞硝氮,且隨著水位變化速率的減慢,上覆水中總氮、硝氮和亞硝氮逐漸增大,氨氮沒有變化;沉積物中的氮素以有機(jī)氮為主,無機(jī)氮中以銨態(tài)氮為主,所占比例從大到小依次為氨氮硝氮亞硝氮,且隨著水位變化速率的減慢,沉積物中銨態(tài)氮逐漸增多,硝態(tài)氮逐漸減小;溫度、pH、DO(沉積物中為溫度、pH、ORP)作為重要的理化參數(shù)對上覆水(沉積物)中的氮形態(tài)的遷移轉(zhuǎn)化產(chǎn)生重要影響。在一定范圍內(nèi),溫度的升高對硝化作用有強(qiáng)烈的促進(jìn)作用,堿性環(huán)境有利于氨氧化作用的進(jìn)行,而氨氧化作用會(huì)使環(huán)境中的pH降低,DO和ORP直接決定了環(huán)境中氮素的好氧轉(zhuǎn)化和厭氧轉(zhuǎn)化;在A-5(水位變化速率為8 cm/d)中,沉積物中的氮素以銨態(tài)氮的形式迅速向上覆水中遷移,氨氧化作用迅速且強(qiáng)烈。在A-15(水位變化速率為2.6cm/d)中,在淹水初期沉積物中的TDN(溶解性總氮)大量向上覆水中釋放,隨后由于上覆水DO的消耗,上覆水中的氨氮逐漸又被沉積物吸附。在A-30(水位變化速率為1.3 cm/d)中,覆水三周后,上覆水中的所有氮素幾乎都已硝態(tài)氮的形式存在。
[Abstract]:The lake wetland due to seasonal changes in the water level, flooded and exposed alternately (alternating wet and dry state, thereby affecting) distribution of sediment and overlying water nitrogen, thus affecting the lake water quality and the nutritional status. As the change law of water interface to the various forms of nitrogen on alternating wet and dry under the influence of wetland sediment - identification, alternate migration regional nitrogen nutrition into the main factors, and provide a theoretical basis for the protection of the lake area, the Dongting Lake is affected by human activities the smaller East Dongting Lake wetland as the research area, the research area of the dry season, water from land to water (shore point, junction point a water point) bottomland wetland sediments were sampled. Through the analysis of the wetland nitrogen and other indicators, the sediments of Dongting Lake wetland basic Nature, and nitrogen forms on Dongting Lake wetland sediments have concluded that changes in driving under the drying wetting; on the basis of the indoor simulation experiment, to explore the sediment water interface in the form of nitrogen migration in the water level change and transformation law. Through the study of field investigation in the wet sediments on the results show that the average the value of dry season in wetland sediment total nitrogen was 0.920g/kg, the coefficient of variation was 0.335; the average value of nitrate nitrogen was 1.379mg/kg, the coefficient of variation was 1.036; the average value of ammonia nitrogen is 10.506mg/kg, the coefficient of variation is the average value of 0.861. in water and wetland sediment total nitrogen was 1.084g/kg, the coefficient of variation was 0.230; average value the nitrate nitrogen is 3.141mg/kg, the coefficient of variation was 1.797; the average value of ammonia nitrogen is 15.397mg/kg, the coefficient of variation for total nitrogen 0.843. nitrate nitrogen and ammonia water, the average and the dry season are compared In addition to the increase of the coefficient of variation of nitrate nitrogen increased significantly, the total nitrogen, the coefficient of variation of ammonia nitrogen with different degree decreased respectively. The variables of the common water period and low water period for Pearson correlation analysis, in the dry season, water content and powder had a significant positive correlation (r=0.296, P0.05), in the flat water period, the water content and the clay was negatively correlated (r=-0.466, P0.01). The results indicated that in the dry season, the main water sediment in combination with powder, in water, sediment water content is likely to cause the loss of clay. The moisture content in water and nitrogen were positively correlated with negative correlation with nitrate, in the dry season, water content and these variables were not significant correlation. It is shown that the influence of water content on nitrogen in different water periods is different. In total nitrogen and nitrate nitrogen in two water seasons were significantly correlated (r=0.420, P0.05; r=0.389, P0.05). During the dry season, and total nitrogen Clay and silt are positively correlated, negatively correlated with sand; in water, total nitrogen and clay showed that the total nitrogen content positively. Especially in the presence of organic nitrogen mainly occurs in clay particle. The samples were grouped by state of overlying water, divided into shore under water samples and samples of two groups were non parametric test showed that in the dry season when water content, ammonia nitrogen, total nitrogen had extremely significant difference, while in the normal water period when water content, nitrate nitrogen has a very significant difference. The overlying water state and different water under different influence on nitrogen speciation in sediment, water sediment biological live strong, contribute to the transformation of nitrogen, total nitrogen level, nitrogen water period, the average value of ammonia and other indicators are greater than in dry season. Total nitrogen in overlying water after sediments, reduce the coefficient of variation of ammonia nitrogen, spatial difference decreased; but the coefficient of variation of nitrate nitrogen in sediments increased after water covered the spatial difference, room increases. In the simulation of changes in the rate of migration under different water levels, nitrogen forms in the sediments of transformation, the rate of change of the water level simulation are respectively 8cm/d, 2.6cm/d and 1.3cm/d (A-5, A-15 and A-30). The simulation results show that the sediments after exposed period overlying water, inorganic nitrogen in overlying water will increase rapidly in the first week and then began to slow down; in the simulation of water level change rate, nitrogen in overlying water were dominated by nitrate nitrogen, the proportion is from big to small in turn Ammonia Nitrate Nitrite, and with the change of water level rate slowed down, the total nitrogen in the overlying water, nitrate nitrogen and nitrite nitrogen increased gradually no change, ammonia nitrogen; nitrogen in sediments with organic nitrogen and inorganic nitrogen in ammonium nitrogen, the proportion is from big to small in turn Ammonia Nitrate Nitrite, and as the water level change rate decreased in the sediments of ammonium nitrogen gradually increased, nitrate nitrogen decreased gradually; Temperature, pH, DO (temperature, sediments pH, ORP) as the important physicochemical parameters of overlying water (sediments) in the migration of nitrogen forms affect transformation. In a certain range, temperature has a strong effect on nitrification, alkaline environment favorable for ammonia oxidation the ammonia oxidation will make the environment in lower pH, DO and ORP directly determines the environment of nitrogen in the aerobic and anaerobic conversion transformation; in A-5 (water level change rate is 8 cm/d), nitrogen in sediments with ammonium nitrogen form rapidly to overlying water migration, ammonia oxidation quickly and strongly. In A-15 (water level change rate of 2.6cm/d), at the beginning of waterlogging in the sediments of TDN (total dissolved nitrogen) to the overlying water release, then the DO of the overlying water consumption of ammonia nitrogen in overlying water and sediment adsorption gradually. In A-30 (water level change rate is 1.3 In cm/d), after three weeks of water coating, almost all nitrogen in the overlying water existed in the form of nitrate nitrogen.

【學(xué)位授予單位】：中國環(huán)境科學(xué)研究院
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：X524

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