基于土地利用与氮稳定同位素的赣江硝酸盐污染源识别

发布时间：2018-03-23 20:38

  本文选题：赣江　切入点：硝酸盐　出处：《江西师范大学》2015年硕士论文

【摘要】：赣江是鄱阳湖的最大支流,赣江硝态氮(NO3--N)是鄱阳湖氮素输入的主要来源,基于土地利用方式和氮稳定同位素查明赣江流域硝酸盐污染来源对鄱阳湖水环境污染监测和维护湖区内水体环境具有重大意义。分别在2013年1月(枯水期)和6月(丰水期)对赣江的干流和支流的硝酸盐氮、氨氮、亚硝酸盐氮质量检测,在土地利用结构分类和空间尺度对比的基础上,采用稳定的氮同位素和相关分析研究赣江硝酸盐的主要来源。在实地调查的基础上合理布设采样点,利用GIS和RS技术为平台,分析赣江流域的土地利用方式,在2013年丰水期和枯水期对赣江流域进行定点调查与采样,采用水化学研究手段分析赣江流域水体中无机氮和氯离子浓度的分布特征,结合流域的土地利用结构类型和氮稳定同位素分析其对无机氮的影响,为识别赣江流域的硝酸盐污染的主要来源和鄱阳湖的水体保护提供了重要的依据。研究结果主要有以下几个方面：(1)对赣江流域2013年1月和6月不同采样点的无机氮浓度进行分析,研究表明赣江流域水体无机氮输出以硝氮(N03--N)形态为主,N03--N含量平均值为1.80mg/L,约占总无机氮的78%；其次为NH4+-N,平均值为0.52mg/L,约占总无机氮20%；NO2--N含量很小,多数采样点低于监测值0.02 mg/L。(2)对赣江流域无机氮分布特征进行分析表明,N03--N含量和NH4+-N含量在1月均大于6月。1月N03--N含量从赣江的源头到下游的波动范围大于6月,NH4+-N含量在1月表现出与6月的相似性,N03--N和NH4+-N的变化差异总体上是1月大于6月。(3)对赣江流域土地利用结构进行分析,结果表明林地面积比例达到62.5%,水田面积比例为18%,旱地和居民建设用地为16%,水田、水域对硝酸盐氮输出起“源”作用,林地和草地等对硝酸盐氮输出起“汇”作用。(4)对赣江流域进行不同空间尺度对比,子流域划分法比缓冲区法更适于赣江流域硝酸盐来源分析,在二级土地利用分类下可以更好的突出土地利用与无机氮之间的作用。二级分类中水田中的丘陵水田对N03--N含量贡献最大。其他水田类型较小。赣江流域中N03--N的主要来源为农村用地,NH4+N的主要来源为居民建设用地中的城镇用地和其它工矿建设用地。(4)赣江流域内的干流的δ1SN- NO3-值在变化幅度小在0.79-5.93%o之间,而支流的δ15N- NO3=值的变化范围较宽在-1.31‰-8.6‰之间,枯水期均值显著小于丰水期,赣江支流由于流经的区域土地利用类型差异大导致硝酸盐污染源出现较大差异性。(6)对赣江流域内无机氮与氮同位素(δ15N- NO3-)相比分析,赣江流域的δ15N-NO3-值主要落合成化肥和土壤氮范围内,说明赣江流域的硝态氮主要来源于农业化肥污染和土壤无机氮。
[Abstract]:The Ganjiang River is the largest tributary of Poyang Lake, and the no _ 3-N _ 3-N of Ganjiang River is the main source of nitrogen input in Poyang Lake. It is of great significance to identify the sources of nitrate pollution in Ganjiang River basin based on land use patterns and nitrogen stable isotopes for monitoring water pollution and maintaining the water environment in Poyang Lake. In January 2013 (dry season) and 6. Nitrate nitrogen in the main and tributaries of the Ganjiang River, The quality of ammonia nitrogen, nitrite nitrogen, based on the classification of land use structure and spatial scale comparison, The main sources of nitrate in Ganjiang River were studied by using stable nitrogen isotope and correlation analysis. On the basis of field investigation, the sampling sites were reasonably set up, and the land use patterns in Ganjiang River Basin were analyzed on the platform of GIS and RS technology. The distribution characteristics of inorganic nitrogen and chloride ion concentration in Ganjiang river basin were analyzed by means of hydrochemical research during the high and low water periods in 2013, and the distribution characteristics of inorganic nitrogen and chloride ions in Ganjiang river basin were analyzed by means of hydrochemistry. The effects of land use structure types and nitrogen stable isotopes on inorganic nitrogen were analyzed. This paper provides an important basis for identifying the main sources of nitrate pollution in the Ganjiang River Basin and the water protection of Poyang Lake. The main results of the study are as follows: 1) the inorganic contents of different sampling sites in January and June 2013 in Ganjiang River Basin. Nitrogen concentration is analyzed, The results show that the inorganic nitrogen output of Ganjiang River basin is mainly composed of nitrate N ~ (03) -N (N _ (03) -N), the average content of which is 1.80 mg / L, accounting for 78% of the total inorganic nitrogen, followed by NH4 -N, with an average value of 0.52 mg / L, accounting for about 20% of the total inorganic nitrogen, the content of no _ 2--N is very small. The distribution characteristics of inorganic nitrogen in Ganjiang River basin were analyzed. The results showed that the contents of N ~ (03) -N and NH4 ~ (-N) in January were greater than in June. The range of fluctuation of N ~ (3 +) from the source of Ganjiang River to the lower reaches in January was larger than that of NH _ 4 in June. The variation of -N content in January was similar to that in June. The difference between N03-N and NH4 -N was generally greater in January than in June, and the land use structure of Ganjiang River basin was analyzed. The results showed that the proportion of forest land and paddy field was 62.5 and 18, and the proportion of dry land and residential construction land was 16. The paddy field and water area played a "source" role in nitrate nitrogen output. Forest land and grassland play a "sink" role in nitrate nitrogen output. (4) the different spatial scales of Ganjiang river basin are compared. The subbasin division method is more suitable than buffer zone method for nitrate source analysis in Ganjiang river basin. The role of land use and inorganic nitrogen can be better highlighted in the secondary land use classification. The hilly paddy fields in the secondary classification have the greatest contribution to the content of N03-N, while the other paddy fields are smaller. The main role of N03-N in the Ganjiang River basin is that of the hilly paddy fields in the secondary classification. The main sources of NH _ 4N from rural land are urban land and other industrial and mining construction land in residential construction land.) the 未 _ 1SN-no _ 3- value of the main stream in the Ganjiang River basin varies slightly in the range of 0.79-5.93o. The variation range of 未 15N- no _ 3 = of tributaries is from -1.31 鈥，

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