本文選題：巖溶區(qū) + 地下河出口�。� 參考：《西南大學(xué)》2015年碩士論文

【摘要】：硝酸鹽污染是水體污染中最常見也是危害最嚴(yán)重的污染之一。近年來,不斷報(bào)道出河流、湖泊、城市地下水等受到硝酸鹽污染,產(chǎn)生水體富營養(yǎng)化以及誘發(fā)食道癌等疾病并對人類健康造成嚴(yán)重危害。在西南巖溶區(qū),已查明的地下河有2836條,總流量達(dá)1482m3.S-1,相當(dāng)于一條黃河,對西南巖溶地區(qū)人民健康和社會經(jīng)濟(jì)發(fā)展有著重要作用的巖溶地下水資源,隨著工農(nóng)業(yè)生產(chǎn)的加劇、城鎮(zhèn)化擴(kuò)張等,也受到了嚴(yán)重的污染,西南地區(qū)巖溶地下水正面臨著變成“下水道”的威脅,西南巖溶地下水污染已十分嚴(yán)重,地下水資源全面告急,保護(hù)巖溶地下水環(huán)境已經(jīng)刻不容緩。我國西南巖溶區(qū)地上、地下雙層結(jié)構(gòu),“三水”轉(zhuǎn)換迅速,使得巖溶地下水對外界環(huán)境的反應(yīng)非常敏感。同時(shí),由于硝酸鹽污染發(fā)生的隨機(jī)性,機(jī)理過程的復(fù)雜性,排散的途徑及排放污染物的不確定性,使得巖溶區(qū)水體中硝酸鹽的時(shí)空分布非常難以監(jiān)測、模擬和控制。因此,在巖溶區(qū)從不同時(shí)間尺度和空間尺度去探討硝酸鹽在巖溶水體中的動(dòng)態(tài)變化及其影響因素顯得十分必要,為全面了解硝酸鹽在巖溶水體中的動(dòng)態(tài)變化提供科學(xué)的認(rèn)識,為防治巖溶區(qū)水體中的硝酸鹽污染提供科學(xué)參考。本文以柳州官村地下河為為例,以官村地下河出口和受官村地下河補(bǔ)給的地表溪流為基礎(chǔ),對比探討地表溪流中硝酸鹽在不同時(shí)間尺度(季節(jié)、降雨、晝夜)上的動(dòng)態(tài)變化及其影響因素。通過研究得到初步結(jié)論：(1)研究區(qū)溪流中N03-離子表現(xiàn)出明顯的季節(jié)變化特征,地下河出口中NO3-離子含量為秋季冬季春季夏季,地表溪流中N03-離子含量為秋季冬季夏季春季,兩個(gè)監(jiān)測點(diǎn)都是旱季偏高,且兩個(gè)監(jiān)測點(diǎn)中N03"離子含量最高值都出現(xiàn)在11月份,主要是由于旱季流量偏低,最低值出現(xiàn)在4月份且春季NO3-離子含量劇烈變化,可能主要受到降雨過程的影響。溪流中NO3-離子在9、10、11、12、2、3、5、8月表現(xiàn)出氮的損失過程,損失量分別為2.46kgN.d-1、1.77 kgN.d-1、3.01 kgN.d-1、2.09 kgN.d-1、2.08 kgN.d-1、17.34 kgN.d-1,在1、4、6、7月表現(xiàn)出氮的增長過程,增長量分別為1.06 kgN.d-1、6.84 kgN.d-1、5.92kgN.d-、0.7 kgN.d-1。溪流中δ15N-NO3-與δ18O-NO3-表現(xiàn)出一定的正相關(guān)關(guān)系(R2=0.38,P0.05),且δ15N-NO3-與δ18O-NO3-的比值大部分落在了1：1的比值附近,說明溪流中在監(jiān)測期間主要發(fā)生了氮的同化作用,只有很小的一部分落在了2：1的附近,說明反硝化作用對溪流中N03"離子的季節(jié)變化影響不大。另外,在一年中溪流中氮的損失量為28.75 kgN.d-1(未包括3、8月的損失量),而增長量為14.52 kgN.d-1,說明在一年的季節(jié)變化監(jiān)測中,溪流中N03"離子主要發(fā)生了氮的損失過程,且主要受到水生植物的同化作用影響。而1、4、6、7月并沒有發(fā)生氮的損失過程,可能主要是由于降雨淋溶作用的影響,使得累積于溪流周圍土壤中的高濃度硝酸鹽進(jìn)入溪流中,從而覆蓋了水生植物同化作用的影響。(2)地下河出口和地表溪流中硝酸鹽降雨后的響應(yīng)總體上表現(xiàn)出相似的變化趨勢,但是地表溪流中硝酸鹽也表現(xiàn)出與地下河出口不同的“異常”變化,且影響因素比地下河出口更加復(fù)雜,地表溪流中硝酸鹽主要受到地下河出口補(bǔ)給水的影響,同時(shí)受到外界雨水以及土壤水的影響。而且不同的降雨強(qiáng)度以及降雨次數(shù)也會使得外界雨水和土壤水以不同的影響作用于地表溪流,首次降雨,外界土壤水中高濃度的N03"離子進(jìn)入地表溪流使得地表溪流中NO3-離子升高,而多次降雨后,土壤水中N03"離子濃度逐漸下降,從而起到稀釋作用。在兩次降雨監(jiān)測中,地下河出口和地表溪流中電導(dǎo)率和N03"離子在R2(2013年8月監(jiān)測中第二次降雨)和2014年5月降雨過程中表現(xiàn)出更加快速的反應(yīng),而R1(2013年8月監(jiān)測中第一次降雨)則相對緩慢,主要是由于R2和2014年5月降雨過程,雨強(qiáng)更大,降雨更加集中有關(guān),也就是說降雨強(qiáng)度會影響電導(dǎo)率和N03"離子響應(yīng)的時(shí)間長短及速率。雨強(qiáng)越大,電導(dǎo)率和NO3-離子反應(yīng)越迅速。(3)2013年7月晝夜監(jiān)測溪流中各物理化學(xué)參數(shù)(T、pH、DO、Spc、pCO2)以及NO3-離子都表現(xiàn)出有規(guī)律的晝夜變化趨勢,其中水溫、DO和pH表現(xiàn)出白天上升晚上下降,而電導(dǎo)率、pC02以及N03"離子則表現(xiàn)出白天下降而晚上上升的趨勢。地下河出口補(bǔ)給對地表溪流各物理化學(xué)參數(shù)及N03"離子表現(xiàn)出有規(guī)律的晝夜變化趨勢影響不大,且溪流的流量變動(dòng)不大,沒有表現(xiàn)出晝夜變化,可以說明在監(jiān)測期間溪流流量也不是驅(qū)動(dòng)溪流中各物理化學(xué)參數(shù)及N03"離子晝夜變化的因素。地表溪流中DO和pC02表現(xiàn)出顯著的負(fù)相關(guān)關(guān)系(R2=0.81,P0.01),且溫度對pC02的貢獻(xiàn)率為27.48%～54.88%,水生植物對水體pC02的影響為45.12%～72.52%,說明監(jiān)測期間溪流中水生植物的光合作用和呼吸作用是DO和CO2的晝夜變化的主要影響因素,同時(shí),NO3-離子與DO表現(xiàn)出明顯的負(fù)相關(guān)關(guān)系(R2=0.52,P0.01),說明DO濃度的晝夜變化影響著NO3-離子濃度的晝夜變化,溪流中N03"離子和pC02的變化存在很弱的相關(guān)性,說明脫氣作用最溪流中NO3-離子的晝夜變化影響不大,同時(shí)說明溪流中水生植物的光合作用和呼吸作用是NO3-離子濃度有規(guī)律的晝夜變化的主要影響因素。NO3"離子總體上表現(xiàn)出下降趨勢,但是在下午出現(xiàn)增長的趨勢,在中午(12：30)達(dá)到增長的最大值3.72 mg.L-1,可見在白天NO3-離子不僅受到因光合作用增強(qiáng)而產(chǎn)生的同化作用影響,主要還受到硝化作用的影響。而在夜間水生植物呼吸作用占據(jù)主導(dǎo)作用,DO含量快速下降,因此同化作用和硝化作用在夜間受到抑制,反硝化過程開始發(fā)揮作用,因此NO3-離子出現(xiàn)下降過程。溪流中N的日變化量為2.59 kgN.d-1,下午以增長過程為主,增長量為0.99kgN.d-1,其余時(shí)間以損失過程為主,其中白天損失量為0.8 kgN.d-1,夜間損失量為0.8kgN.d-1,通過N的變化量計(jì)算各個(gè)作用所占的比例,下午以硝化作用為主,增長量為0.99kgN.d-1,占日變化量的38%,夜間以反硝化作用為主,損失量為0.8 kgN.d-1,占日變化量的31%,白天損失量為0.8 kgN.d-1,以同化作用為主,占日變化量的31%,因此可以說N以生物作用為主的日變化量中,硝化作用占38%,同化作用占31%,反硝化作用占31%。2014年7月晝夜監(jiān)測溪流中各物理化學(xué)參數(shù)(T、pH、DO、Spc、pCO2)表現(xiàn)出有規(guī)律的晝夜變化趨勢,其中水溫、DO和pH表現(xiàn)出白天上升晚上下降,而電導(dǎo)率、pC02則表現(xiàn)出白天下降而晚上上升的趨勢。但是溪流中NO3-離子并沒有表現(xiàn)出與DO一致的晝夜變化,兩者沒有表現(xiàn)出相關(guān)性(R20.03),515N和δ18O同樣沒有表現(xiàn)出有規(guī)律的晝夜變化趨勢,NO3-離子與δ15N表現(xiàn)出較小的相關(guān)性(R2=0.18,P=0.03),與δ18O沒有表現(xiàn)出相關(guān)性(R2=0.01,P-=0.25),且δ515N和δ18O之間也沒有表現(xiàn)出相關(guān)性(R2=0.008,P=0.25)。δ15N和δ18O沒有表現(xiàn)出相關(guān)性,兩者比值有很小的一部分落在1：1比值區(qū)間,有一部分落在2：1的比值區(qū)間,說明溪流中同化作用作用和反硝化作用對溪流中NO3-離子的晝夜變化產(chǎn)生了一定的影響,溪流中主要發(fā)生了氮的損失過程,損失量為2.71kgN.d-1,可能受到反硝化作用和同化作用一定的影響,但是溪流中δ15N-NO3-和δ18N-NO3-并沒有表現(xiàn)出相關(guān)性變化,可能主要受到硝化作用和氮多種混合源的影響,同時(shí)N03"離子濃度與流量表現(xiàn)出一定的相關(guān)性(R2=0.25,P=0.03),說明隨著時(shí)間和來源變化的上游補(bǔ)給也影響著溪流中N03"離子濃度的晝夜變化。同時(shí)說明是溪流中N03-離子的晝夜變化受到生物作用和隨著時(shí)間和來源變化的上游補(bǔ)給的物理過程的共同影響。
[Abstract]:Nitrate pollution is one of the most common and most serious pollution in water pollution. In recent years, it has been reported that rivers, lakes, urban groundwater, etc. are polluted by nitrate, produce water eutrophication, induce esophageal cancer and other diseases, and cause serious danger to human health. In the southwest karst area, 2836 underground rivers have been identified. The total flow rate is 1482m3.S-1, which is equivalent to a the Yellow River, the karst groundwater resources which have an important role in the people's health and social and economic development in the karst region of Southwest China. With the intensification of industrial and agricultural production, the expansion of urbanization and so on, the karst groundwater in Southwest China is facing the threat of "sewer", and southwest China is facing the threat of "sewer". The pollution of karst groundwater is very serious, and the groundwater resources are completely urgent. It is urgent to protect the karst groundwater environment. In the karst area of Southwest China, the underground double layer structure and the "three water" change quickly, making the karst groundwater reacting to the external environment very sensitive. It is very difficult to monitor, simulate and control the spatio-temporal distribution of nitrate in karst area. Therefore, it is necessary to explore the dynamic changes and influence factors of nitrate in karst water from different time scale and space scale in karst area. It provides a scientific understanding of the dynamic changes of nitrate in karst water body, and provides scientific reference for the prevention and control of nitrate pollution in the water of karst area. This paper takes the underground river in Guan village of Liuzhou as an example, based on the surface stream of the underground river outlet of Guan Cun and the underground river recharged by the underground river in the official village. The dynamic changes and its influencing factors on the time scale (season, rainfall, day and night) have been obtained. (1) the N03- ions in the stream of the study area show obvious seasonal variation, and the content of NO3- ions in the underground river exit is in the spring and winter in autumn and winter, and the content of N03- ions in the surface stream is two in autumn and winter in summer and winter. The monitoring points are all high in the dry season, and the highest value of N03 "ion content in the two monitoring points is in November, mainly due to the low flow in the dry season, the lowest value in April and the sharp change of the NO3- ion content in spring, which may be mainly affected by the rainfall process. The NO3- ion in the stream shows the loss of nitrogen in the month of 9,10,11,12,2,3,5,8. The loss amount is 2.46kgN.d-1,1.77 kgN.d-1,3.01 kgN.d-1,2.09 kgN.d-1,2.08 kgN.d-1,17.34 kgN.d-1 respectively, and the growth process of nitrogen in 1,4,6,7 month is 1.06 kgN.d-1,6.84 kgN.d-1,5.92kgN.d-, and the delta 15N-NO3- and delta 18O-NO3- in the 0.7 kgN.d-1. stream show a certain positive correlation. The ratio of O3- to delta 18O-NO3- falls near the ratio of 1:1, indicating that nitrogen assimilation occurs mainly during the monitoring of streams. Only a small portion of the stream falls near the 2:1, indicating that denitrification has little effect on the seasonal changes in the ions of N03 in the stream. In addition, the loss of nitrogen in a stream is 28.75 in a year. KgN.d-1 (excluding the loss of 3,8 months), and the increase of 14.52 kgN.d-1, indicates that in the seasonal variation monitoring of one year, the N03 "ions in the stream occur mainly in the process of nitrogen loss and are mainly influenced by the assimilation of aquatic plants. And the loss process of nitrogen is not occurring in 1,4,6,7 months, probably mainly due to rainfall leaching. The effect is that the high concentration of nitrate accumulated in the soil around the stream enters the stream and covers the influence of the assimilation of aquatic plants. (2) the response of nitrate to the rain in the underground river outlet and the surface stream shows a similar trend in general, but the nitrate in the surface stream is also different from the underground river outlet. The "abnormal" change is more complex than the underground river outlet. The nitrate in the surface stream is mainly influenced by the supply water of the underground river outlet, and is affected by the external rain and the soil water. And the different rainfall intensity and the rainfall times also make the external rain and soil water affected by different effects on the ground. For the first time, the high concentration of N03 "ions into the surface stream of the soil water makes the NO3- ions in the surface streams increase, and the concentration of N03 ions in the soil water decreases gradually after several rainfall. In the two rainfall monitoring, the conductivity of the underground river and the surface streams and the N03" ions are in R2 (2013 8). The second rainfall during monthly monitoring and the rainfall in May 2014 showed a more rapid response, while R1 (the first rainfall in August 2013) was relatively slow, mainly due to the rainfall process in R2 and May 2014, which was stronger and more concentrated, which means that the intensity of rainfall would affect the time of electrical conductivity and the time of N03 "ion response. The greater the length and speed. The greater the intensity of the rain, the faster the electrical conductivity and the reaction of the NO3- ions. (3) all the physical and chemical parameters (T, pH, DO, Spc, pCO2) and NO3- ions in the day and night monitoring of the stream in July 2013 showed a regular day and night trend, in which the temperature, DO and pH showed a decline in the white sky at night, while the conductivity, pC02 and N03 "ions" showed The trend of daytime decline and evening rise. Underground river export recharge has little influence on the physical and chemical parameters of the surface streams and the regular diurnal changes of N03 "ions, and the flow of streams is not changed, and there is no day and night change. It can be shown that the stream flow is not a physical chemical reference in the driving stream during the monitoring. The factors of number and N03 "ion diurnal variation. DO and pC02 in surface streams show significant negative correlation (R2=0.81, P0.01), and the contribution rate of temperature to pC02 is 27.48% to 54.88%, and the effect of aquatic plants on water pC02 is 45.12% ~ 72.52%, indicating that the photosynthesis and respiration of aquatic plants during the monitoring are the day of DO and CO2. The main influence factors of night change, at the same time, NO3- ions and DO showed a significant negative correlation (R2=0.52, P0.01), indicating that the diurnal variation of the concentration of DO affects the diurnal variation of the concentration of NO3- ions, and there is a weak correlation between the changes of the N03 "ions and pC02 in the stream, and that the diurnal changes of the NO3- ions in the most stream of degassing action have little influence. At the same time, it is indicated that photosynthesis and respiration of aquatic plants in the stream are the main influencing factors of the regular diurnal changes of NO3- ion concentration,.NO3 "ions generally show a downward trend, but the trend of growth in the afternoon, at 12:30), reaches the maximum value of 3.72 mg.L-1, which shows that NO3- ions are not only in the daytime. The effect of assimilation caused by enhanced photosynthesis is mainly influenced by nitrification. While the respiration of the aquatic plants occupies the leading role in the night, the DO content decreases rapidly. Therefore, the assimilation and nitrification are inhibited at night and the denitrification process begins to play a role, so the NO3- ion decreases. N in the stream. The daily change amount is 2.59 kgN.d-1. In the afternoon, the growth process is based on the growth process, the growth is 0.99kgN.d-1, the rest time is dominated by the loss process, of which the daytime loss is 0.8 kgN.d-1, the night loss is 0.8kgN.d-1, and the proportion of each function is calculated by the change of N. In the afternoon, the nitrification is the main factor, the increase is 0.99kgN.d-1, accounting for the daily change. 38% of the amount of denitrification at night, the loss amount is 0.8 kgN.d-1, accounting for 31% of the daily change and 0.8 kgN.d-1 in the daytime, which is dominated by assimilation, accounting for 31% of the daily change. Therefore, the denitrification is 38%, the assimilation is 31%, and the denitrification account for the day and night prison of 31%.2014 year in July. The physical and chemical parameters (T, pH, DO, Spc, pCO2) in a measured stream show a regular trend of day and night change, in which water temperature, DO and pH show a decline in the night, while the conductivity and pC02 show a trend of rising in the white world and at night. However, the NO3- separated from the stream does not show the same day and night change as DO. The correlation (R20.03), 515N and delta 18O did not show a regular day and night trend, NO3- ions and delta 15N showed a smaller correlation (R2=0.18, P=0.03), and did not show a correlation with delta 18O (R2=0.01, P-=0.25), and there was no correlation between Delta 515N and delta 18O. [Delta] and delta 18O did not show correlation. A small part of the ratio falls on the ratio interval of the 1:1 ratio, and some of them fall on the ratio range of the 2:1. It shows that the effect of assimilation and denitrification on the diurnal changes of NO3- ions in the stream have a certain effect on the stream, and the loss process of nitrogen in the stream is 2.71kgN.d-1, which may be affected by the anti nitrite. The effects of chemical and assimilation are certain, but the delta 15N-NO3- and delta 18N-NO3- in the stream do not show a correlation change, which may be mainly influenced by nitrification and multiple nitrogen sources, while the N03 "ion concentration and flow show a certain correlation (R2=0.25, P= 0.03), indicating the upstream recharge with time and source changes, too. The diurnal variation of N03 "ion concentration in a stream is influenced by the physical processes of the physical processes of the diurnal changes of the N03- ions in the streams by the biological action and the upstream recharge with time and source changes.
【學(xué)位授予單位】：西南大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：X523

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