洱海氮來源及對上覆水的影響
發(fā)布時間：2019-03-25 16:08
【摘要】：洱海是云貴高原第二大淡水湖泊,近些年來水質(zhì)處于下降階段,存在富營養(yǎng)化風(fēng)險,氮作為湖泊富營養(yǎng)化的主要影響因素之一,對于氮源的控制越發(fā)重要。本文以洱海入湖河流、干濕沉降、表層沉積物和上覆水為研究對象,利用碳氮元素分析和穩(wěn)定同位素技術(shù),對洱海氮來源以及對上覆水的影響和貢獻進行研究,為控制洱海氮源進而抑制洱海富營養(yǎng)化進程提供了理論基礎(chǔ)和科學(xué)建議。得到的主要結(jié)論如下:(1)洱海入湖河流TN和PN的變化總體上呈現(xiàn)從夏季到冬季依次下降,然后從冬季到春季有所增加的趨勢,這種趨勢與洱海不同月份入湖水量變化相關(guān),主要變化原因在于水土流失;對入湖河流氮的來源研究結(jié)果顯示土壤氮、化肥、廢水和水生植物的貢獻居多,其中化肥和廢水的影響有季節(jié)性特點。干濕沉降TN隨季節(jié)呈現(xiàn)波動式下降,與降雨量呈顯著負相關(guān);對干濕沉降來源研究結(jié)果顯示,土壤氮、人畜糞便排放和燃料燃燒對干濕沉降貢獻較大,并且沒有季節(jié)性變化。表層沉積物TN和氨氮的擴散通量均表現(xiàn)為中部南部北部,表層沉積物中氮的釋放主要以氨氮為主,并且季節(jié)性變化較大;對沉積物氮來源研究結(jié)果顯示北部湖區(qū)以土壤流失氮、化肥和陸源有機質(zhì)的貢獻為主,中部以水源性有機質(zhì)貢獻居多,南部則屬于陸源和水源混合型來源。(2)洱海上覆水氮的來源較為復(fù)雜,屬于外源輸入和內(nèi)源釋放的共同作用,洱海上覆水顆粒態(tài)有機物氮來源以浮游生物、水生植物和陸源C3植物為主。洱海夏季和秋季氮的主要輸入途徑中,河流和浮游生物的貢獻較多,南部湖區(qū)河流貢獻高于其余兩個湖區(qū),夏秋兩個季節(jié)中都以河流貢獻為最多,浮游生物次之。不同來源入湖氮中,以土壤氮、化肥和浮游生物貢獻居多,洱海上覆水體中總體上外源和內(nèi)源貢獻相當(dāng),外源以河流輸入為主,內(nèi)源以浮游生物貢獻為主。洱海三大湖區(qū)上覆水體中自表層至底層,表層以外源輸入貢獻為主,主要為河流的貢獻,中層至底層內(nèi)源的貢獻逐漸增大,但同時外源影響依然存在。洱海上覆水氮的來源貢獻與輸入途徑密不可分,這些不同來源入湖氮的貢獻與不同途徑的入湖負荷有必然聯(lián)系,幾種輸入途徑的入湖負荷體現(xiàn)出入湖河流內(nèi)源釋放其它途徑干濕沉降的特點,這與不同途徑入湖氮對上覆水的貢獻研究結(jié)果是一致的,不同途徑的入湖負荷與不同途徑入湖氮對上覆水的貢獻以及不同來源入湖氮對上覆水的貢獻是呈正相關(guān)的。(3)根據(jù)研究結(jié)果從控制洱海上覆水氮的源頭考慮,提出幾點建議:(1)采取水土固持措施,減少洱海流域內(nèi)的水土流失;(2)減少洱海流域內(nèi)氮肥的施用量,大力推廣新興農(nóng)業(yè);(3)控制流域內(nèi)生活污水和工業(yè)廢水的排放,推廣新興工藝;(4)采取內(nèi)源控制措施,減少內(nèi)源氮的釋放。
[Abstract]:Erhai Lake is the second largest freshwater lake in the Yunnan-Guizhou Plateau. In recent years, the water quality is in a declining stage and there is a risk of eutrophication. Nitrogen, as one of the main influencing factors of lake eutrophication, is becoming more and more important for the control of nitrogen sources. In this paper, the source of nitrogen and the influence and contribution to the overlying water of Erhai Lake are studied by using carbon and nitrogen element analysis and stable isotope technique, taking the rivers of Erhai Lake into lake, dry and wet sedimentation, surface sediments and overlying water as the object of study. It provides theoretical basis and scientific suggestion for controlling nitrogen source and inhibiting eutrophication process in Erhai Lake. The main conclusions are as follows: (1) the variation of TN and PN in Erhai Lake generally decreased from summer to winter, and then increased from winter to spring. This trend is related to the change of water quantity in Erhai Lake in different months. The main reason for the change is soil and water loss; The results showed that the contribution of soil nitrogen, chemical fertilizer, wastewater and aquatic plants was the most, and the effects of fertilizer and wastewater had seasonal characteristics. The TN of dry and wet deposition decreased with season, which was negatively correlated with precipitation, and the results showed that the contribution of soil nitrogen, human and animal excrement emission and fuel combustion to dry and wet deposition was significant, and there was no seasonal change. The diffusion fluxes of TN and NH _ 3-N in surface sediments are both in the south of central and northern parts of China. The release of nitrogen in surface sediments is dominated by ammonia-nitrogen, and the seasonal variation is great. The results of the study on the source of sediment nitrogen show that the contribution of soil loss nitrogen, fertilizer and land-derived organic matter is dominant in the northern lake area, and the contribution of water-derived organic matter is mostly in the middle of the lake. The southern part belongs to the mixed source of land source and water source. (2) the source of water nitrogen in Erhai Lake is complex, which belongs to the interaction of exogenous input and endogenous release, and the source of granular organic nitrogen in Erhai Lake is plankton. Aquatic plants and terrestrial C3 plants are dominant. In the summer and autumn of Erhai Lake, the contribution of rivers and plankton is more than that of the other two lakes. The contribution of rivers is the highest in summer and autumn, and the second is plankton in summer and autumn, while the contribution of rivers is higher in the southern lake than in the other two lakes in the summer and autumn of Erhai Lake. The contribution of soil nitrogen, chemical fertilizer and plankton was mostly from different sources of nitrogen in lake. The contribution of exogenous and endogenous in overlying water body of Erhai Lake was equal, the input of exogenous source was mainly river, and the contribution of endogenous plankton was dominant. In the overlying water body of Erhai Lake from surface to bottom, the external input is the main contribution, which is mainly the contribution of rivers. The endogenous contribution from middle to bottom gradually increases, but at the same time, the influence of exogenous sources still exists. The source contribution of water nitrogen in Erhai Lake is inextricably related to the input pathway, and the contribution of these different sources of nitrogen to the lake is bound to be related to the loading of different ways of entering the lake. The loading of several input channels reflects the characteristics of dry and wet deposition of endogenous release of other channels in and out of lake rivers, which is consistent with the research results of the contribution of different ways of entering lake nitrogen to the overlying water. There is a positive correlation between the input load of different channels and the contribution of nitrogen from different sources to the overlying water. (3) according to the results of the study, the source of controlling the nitrogen in the overlying water of Erhai Lake is considered, and the contribution of nitrogen from different sources to the overlying water is positively correlated with the contribution of nitrogen from different sources to the overlying water. Some suggestions are put forward as follows: (1) adopting soil and water fixation measures to reduce soil and water loss in Erhai Lake Basin; (2) reduce the amount of nitrogen fertilizer applied in Erhai Lake basin and popularize the emerging agriculture; (3) control the discharge of domestic sewage and industrial wastewater in the basin and popularize the new technology; (4) adopt endogenous control measures to reduce the release of endogenous nitrogen.
【學(xué)位授予單位】：南昌大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2016
【分類號】：X524
[Abstract]:Erhai Lake is the second largest freshwater lake in the Yunnan-Guizhou Plateau. In recent years, the water quality is in a declining stage and there is a risk of eutrophication. Nitrogen, as one of the main influencing factors of lake eutrophication, is becoming more and more important for the control of nitrogen sources. In this paper, the source of nitrogen and the influence and contribution to the overlying water of Erhai Lake are studied by using carbon and nitrogen element analysis and stable isotope technique, taking the rivers of Erhai Lake into lake, dry and wet sedimentation, surface sediments and overlying water as the object of study. It provides theoretical basis and scientific suggestion for controlling nitrogen source and inhibiting eutrophication process in Erhai Lake. The main conclusions are as follows: (1) the variation of TN and PN in Erhai Lake generally decreased from summer to winter, and then increased from winter to spring. This trend is related to the change of water quantity in Erhai Lake in different months. The main reason for the change is soil and water loss; The results showed that the contribution of soil nitrogen, chemical fertilizer, wastewater and aquatic plants was the most, and the effects of fertilizer and wastewater had seasonal characteristics. The TN of dry and wet deposition decreased with season, which was negatively correlated with precipitation, and the results showed that the contribution of soil nitrogen, human and animal excrement emission and fuel combustion to dry and wet deposition was significant, and there was no seasonal change. The diffusion fluxes of TN and NH _ 3-N in surface sediments are both in the south of central and northern parts of China. The release of nitrogen in surface sediments is dominated by ammonia-nitrogen, and the seasonal variation is great. The results of the study on the source of sediment nitrogen show that the contribution of soil loss nitrogen, fertilizer and land-derived organic matter is dominant in the northern lake area, and the contribution of water-derived organic matter is mostly in the middle of the lake. The southern part belongs to the mixed source of land source and water source. (2) the source of water nitrogen in Erhai Lake is complex, which belongs to the interaction of exogenous input and endogenous release, and the source of granular organic nitrogen in Erhai Lake is plankton. Aquatic plants and terrestrial C3 plants are dominant. In the summer and autumn of Erhai Lake, the contribution of rivers and plankton is more than that of the other two lakes. The contribution of rivers is the highest in summer and autumn, and the second is plankton in summer and autumn, while the contribution of rivers is higher in the southern lake than in the other two lakes in the summer and autumn of Erhai Lake. The contribution of soil nitrogen, chemical fertilizer and plankton was mostly from different sources of nitrogen in lake. The contribution of exogenous and endogenous in overlying water body of Erhai Lake was equal, the input of exogenous source was mainly river, and the contribution of endogenous plankton was dominant. In the overlying water body of Erhai Lake from surface to bottom, the external input is the main contribution, which is mainly the contribution of rivers. The endogenous contribution from middle to bottom gradually increases, but at the same time, the influence of exogenous sources still exists. The source contribution of water nitrogen in Erhai Lake is inextricably related to the input pathway, and the contribution of these different sources of nitrogen to the lake is bound to be related to the loading of different ways of entering the lake. The loading of several input channels reflects the characteristics of dry and wet deposition of endogenous release of other channels in and out of lake rivers, which is consistent with the research results of the contribution of different ways of entering lake nitrogen to the overlying water. There is a positive correlation between the input load of different channels and the contribution of nitrogen from different sources to the overlying water. (3) according to the results of the study, the source of controlling the nitrogen in the overlying water of Erhai Lake is considered, and the contribution of nitrogen from different sources to the overlying water is positively correlated with the contribution of nitrogen from different sources to the overlying water. Some suggestions are put forward as follows: (1) adopting soil and water fixation measures to reduce soil and water loss in Erhai Lake Basin; (2) reduce the amount of nitrogen fertilizer applied in Erhai Lake basin and popularize the emerging agriculture; (3) control the discharge of domestic sewage and industrial wastewater in the basin and popularize the new technology; (4) adopt endogenous control measures to reduce the release of endogenous nitrogen.
【學(xué)位授予單位】：南昌大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2016
【分類號】：X524
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