汉江流域上游氮污染的时空变化格局及其来源解析

发布时间：2018-01-18 10:24

本文关键词：汉江流域上游氮污染的时空变化格局及其来源解析　出处：《中国科学院武汉植物园》2017年博士论文　论文类型：学位论文

【摘要】：随着社会经济的发展以及人口数量的增加,大量含有高浓度氮素的工业废水和生活污水排入河流,引起了一系列生态环境问题,如水质恶化、水体富营养化、藻类大量爆发以及生物多样性减少等。氮素超标目前已成为中国乃至全球范围内河流的主要水污染问题,严重影响河流的水环境质量。因此,如何有效控制河流氮素水平,缓解氮污染的危害,成为当前亟待解决的环境问题之一。汉江中上游作为我国南水北调中线工程的水源地,其水质状况也引起了广泛的关注。本研究针对汉江上游水体氮污染问题,选取汉江上游段和汉江上游支流金水河为研究对象(前者受人类活动干扰较大,后者极少受到人为干扰),采用氮氧同位素技术并结合方差分析、主成分分析和聚类分析等统计分析方法,分析和对比了两流域的氮污染时空分布特征,并针对水体中硝酸盐和悬浮颗粒物进行了来源解析,揭示其生物地球化学意义,以期为汉江流域的水质管理和水污染治理提供参考。主要结果如下:(1)NO_3~-N是汉江上游水体中氮的主要存在形式,NO_3~-N与TN浓度的时空分布规律较为一致,部分地区水质较好,人类活动频繁的区域氮浓度急剧增加。年际动态显示,在 2013-2014、2014-2015、2015-2016三个年度中,2014-2015年度的NO_3~-和TN浓度显著高于其它年度。该年度水质最差,氮含量较高。2015-2016年度汉江中上游的水质有所改善,污染程度减轻。根据水体中的氮存在形式与其来源的关系,发现汉江中上游在2014-2015年度受农业活动影响较大,而2015-2016年度主要受城市以及工业污水的污染。总体上,该流域水体氮含量呈现明显的季节动态变化规律,丰水期的氮素浓度较枯水期高,氮污染程度在年际间变化趋势较明显。(2)汉江上游河段各季节水体硝酸盐的来源明显不同。2013年秋季和冬季属于非生长季节,水体主要受到工业废水及生活污水的影响。2014年4月(春)水体硝酸盐主要来源于土壤有机氮、大气沉降和化肥,仅少数几个位于城市内的样点受工业废水的影响严重。2014年7月(夏)少数河段硝酸盐来源于生活污水或者动物粪便,多数河段受到土壤有机氮或工业废水的影响。2015年4月(春)水体硝酸盐的来源较多,但是受到降雨量的限制,其来源主要为化肥、生活污水、土壤有机氮、及工业废水。2015年7月(夏)水体硝酸盐氮同位素的平均水平较高,水体硝酸盐主要来源于降水、生活污水、动物粪便及化肥。2014年11月(秋)和2015年1月(冬),水体硝酸盐主要来源于降雨、工业废水及土壤有机氮,冬季时降雨来源可以忽略。2015年11月到2016年7月,广泛的同位素值分布体现了这一时期水体中硝酸盐来源的复杂性。利用主成分分析对水环境因子与氮同位素变化的关系进行分析发现,浊度与水体硝酸盐的氮同位素值相关性最大。结合氮污染的特征,于2016年11月对几个代表性样点进行了水体硝酸盐的氧同位素分析,结果清晰准确地识别了各样点水体硝酸盐的来源,且水体中硝酸盐浓度的变化受到硝化作用和反硝化作用的影响。(3)金水河流域中,硝态氮是水体可溶性无机氮的主要存在形式,丰水期的氮浓度较枯水期更高,11月份水体氮浓度最低。氮素的空间分布特征显示,金水河中游河段氮含量较低,水质较好,而上、下游河段相对受到一定人为活动的干扰。(4)金水河流域水体中硝酸盐主要来源于大气沉降、化肥、土壤有机氮和生活污水。悬浮颗粒氮主要来源于大气沉降和农业化肥,且不同季节来源差异较大,其中冬季主要受到人类活动的影响。这可能与陆源氮输入及水体中复杂的氮循环过程有关悬浮颗粒物的δ15N-SPM值7月份最高,1月份和11月份次之,4月份最低。除了1月份硝化作用占主导因素以外,各个季节都存在一定的同化与分解作用,并且7月份强烈的分解作用导致其较高的δ15N-SPM值。金水河水体中氮含量在空间分布上变化特征不明显。
[Abstract]:With the development of social economy and the increase of population, with a large number of high concentration nitrogen industrial wastewater and domestic sewage discharged into the river, causing a series of ecological environment problems, such as deterioration of water quality, eutrophication, algae outbreak and the reduction of biodiversity. Nitrogen exceed the standard has become one of the major problems of water pollution and global Chinese within the scope of the river, seriously affected the quality of the water environment of the river. Therefore, how to effectively control the nitrogen level, alleviate the harm of nitrogen pollution, has become one of the most urgent environmental issues. In the upper reaches of Hanjiang River as water source of Middle Route Project of South to North Water Transfer in China, the water quality has attracted wide attention in this study. The upper reaches of Hanjiang River water nitrogen pollution problem, select the upper reaches of the Hanjiang River and tributaries of the upper reaches of the Hanjiang River water river as the research object (the former impacted by human activities, the Less disturbed), using nitrogen and oxygen isotope technique combined with variance analysis, principal component analysis and cluster analysis methods, analysis and comparison of the temporal and spatial distribution characteristics of nitrogen pollution in water bodies and two basins, nitrate and suspended particulate source analysis, reveal its biogeochemical significance, provide the reference to the Hanjiang River Basin Water management and water pollution control. The main results are as follows: (1) NO_3~-N is the main form of the upper reaches of the Hanjiang River water nitrogen, spatial distribution of NO_3~-N and TN concentration is the same, in some areas with better water quality, nitrogen concentration areas of frequent human activities increased sharply. The annual dynamic display, in 2013-20142014-20152015-2016 three year, 2014-2015 year NO_3~- and TN were significantly higher than other year. This year the worst water quality, higher nitrogen content in Hanjiang River.2015-2016 Tour the water quality has improved, to reduce the degree of pollution. According to the relationship of nitrogen in the water form its origin, found in the upper reaches of Hanjiang River by agricultural activities in 2014-2015 and 2015-2016 is affected mainly by the annual city and industrial sewage pollution. On the whole the content of nitrogen in the basin has obvious seasonal dynamics, Feng concentration of nitrogen in water period than in dry season, the annual change in the trend of nitrogen pollution degree is obvious. (2) the seasonal water sources upstream Hanjiang River nitrate was significantly different in.2013 autumn and winter are non growing season, water is mainly affected by the impact of domestic sewage and industrial wastewater.2014 in April (spring water) nitrate comes from soil organic nitrogen, atmospheric deposition and chemical fertilizer, only a few samples located within the city affected by industrial wastewater serious.2014 in July (summer) a section of nitrate From sewage or animal waste, most of April by.2015 effects of soil organic nitrogen or industrial wastewater (spring) water source more nitrate, but limited by rainfall, the main source of chemical fertilizers, sewage, soil organic nitrogen, and industrial wastewater.2015 in July (summer) nitrate nitrogen isotope the average water level is higher, the water nitrate mainly from precipitation, sewage, animal manure and fertilizer.2014 in November (Autumn) and January 2015 (winter), water nitrate mainly comes from rainfall, industrial wastewater and soil organic nitrogen sources, winter rainfall can be ignored during.2015 November to July 2016, wide range of isotope values the distribution reflects the complexity of the water sources of nitrate in this period. The analysis of the relationship between water environment factors and nitrogen isotope analysis using principal components, turbidity and water nitrate Nitrogen isotope values of maximum correlation. Combined with the characteristics of nitrogen pollution, in November 2016 of several representative samples of oxygen isotope water nitrate, the results clearly and accurately identify the source of water nitrate, nitrate concentration and changes in water affected by nitrification and denitrification. (3) Jinshuihe River, nitrate nitrogen is the main form of water soluble inorganic nitrogen, nitrogen concentration of the water phase were higher in dry season, November. The lowest nitrogen concentration in water body shows the spatial distribution characteristics of nitrogen, Jinshuihe river section in the lower nitrogen content, better water quality, and on the downstream interference the relative subject to certain human activities. (4) the nitrate water Jinshuihe River Basin mainly comes from atmospheric deposition, chemical fertilizer, soil organic nitrogen and sewage. The suspended particulate nitrogen from atmospheric deposition and agricultural fertilizer, and different The source of seasonal differences, the winter is mainly affected by human activities. This May 8 15N-SPM suspended particles associated with the nitrogen cycle nitrogen complex in water and terrigenous input value was highest in July, January and November of April, the lowest in January. Nitrification is the dominant factor, each season have effect and decomposition the assimilation, and in July a strong decomposition leads to a higher value. The 15N-SPM value of nitrogen content Jinshuihe water changes in the spatial distribution characteristic is not obvious.

【学位授予单位】：中国科学院武汉植物园
【学位级别】：博士
【学位授予年份】：2017
【分类号】：X522

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