三峡库区腹地大气氮湿沉降研究

发布时间：2018-03-02 16:22

本文选题：氮湿沉降　切入点：降雨量　出处：《重庆三峡学院》2017年硕士论文　论文类型：学位论文

【摘要】：大气氮沉降,作为全球氮循环的一个重要组成部分,在中国近几十年急剧增长。虽然这些氮对生态系统的输入能增加食物产量和刺激植物生长,但过量的氮输入也对自然生态系统和人类带来一系列的负面影响,包括土壤和水体酸化、土壤缓冲能力和生物多样性降低、人类健康风险增大及温室气体失衡等。可见,区域氮沉降及其生态效应已成为研究热点,开展大气氮沉降的研究势在必行。三峡库区是长江中上游地区的生态环境屏障和西部生态环境建设的重点,其大气环境变化已越来越受到关注。基于氮沉降相关研究较少和库区生态的敏感性,本研究立足于三峡库区腹地,选择典型功能区,利用APS-3A型降水降尘自动采样器,于2014年7月～2016年5月对三峡库区腹地万州(城区)和高阳(镇郊)进行了近2年的大气氮湿沉降和降水酸度等定位观测,本研究不仅能为库区环境现状评价提供基础数据,还能对完善三峡库区腹地生态系统氮素资源管理与评价等具有十分重要的科学意义。取得了如下主要研究结论:1.万州降水pH月均加权值为5.47,酸雨发生频率为40.85%;月均降雨量为90.0 mm,年均降雨量达1079,7 mm,可溶性无机氮(DIN)、铵态氮(NH4+-N)和硝态氮(NO_3~--N)年均沉降通量分别达12.40、8.18和4.22 kgN,hm~(-2)·a-1,铵态氮/硝态氮平均比值为1.79。2.高阳降水pH月均加权值为5.49.酸雨发生频率为33.93%;月均降雨量为69.4 mm,年均降雨量达832.8 mm,DIN、NH4+-N和NO_3~--N年均沉降通量分别达6.40、4.05和2.35 kgN·hm~(-2)·a-1,铵态氮/硝态氮平均比值为1.61。3.将监测期内两地NH_4~--N、NO_3~--N和DIN年均浓度和年均通量值与部分研究结果对比.两地3种无机氮浓度均低于重庆近郊(沙坪坝区)、远郊(北碚区歇马场)和林区(仙女山国家森林公园)的浓度,高于受人类活动影响较小的海北和林芝等地,而两个监测点的3种无机氮年沉降通量分别低于大部分相同下垫面类型的监测点,综合分析.得出本研究区的NH4+-N、NO3.--N和DIN浓度均处于中等水平,年均通量值处于较低水平,但受人为活动影响比较严重。4.通过对两地降水进行后向轨迹分析,得出两地降水气团均主要来自于西北和西南方向.两地降水均受陆地性气团的作用强于海洋性气团。
[Abstract]:Atmospheric nitrogen deposition, an important part of the global nitrogen cycle, has grown dramatically in China in recent decades. However, excessive nitrogen input also has a series of negative effects on natural ecosystems and human beings, including acidification of soil and water bodies, reduction of soil buffer capacity and biodiversity, increased risks to human health and imbalance of greenhouse gases. Regional nitrogen deposition and its ecological effects have become a hot research topic, and it is imperative to carry out the research on atmospheric nitrogen deposition. The three Gorges Reservoir area is the focus of ecological environmental barrier in the upper and middle reaches of the Yangtze River and the ecological environment construction in the western part of China. The change of atmospheric environment has been paid more and more attention. Based on the less research on nitrogen deposition and the ecological sensitivity of the reservoir area, this study is based on the hinterland of the three Gorges Reservoir area, selects the typical function area, and makes use of the APS-3A automatic sampler for precipitation and dust fall. The atmospheric nitrogen wet deposition and precipitation acidity of Wanzhou (urban) and Gaoyang (suburbs) in the hinterland of the three Gorges Reservoir area were observed from July 2014 to May 2016. This study can not only provide the basic data for the assessment of the environmental situation in the reservoir area. It is also of great scientific significance to improve the management and evaluation of nitrogen resources in the ecosystem of the hinterland of the three Gorges Reservoir area. The main conclusions are as follows: 1. The average monthly weighted value of precipitation pH in Wanzhou is 5.47, the frequency of acid rain is 40.85, and the frequency of acid rain is 40.85 per month. The average precipitation was 90.0 mm, and the average annual rainfall was 1079 mm. The average annual deposition fluxes of soluble inorganic nitrogen (DINN), ammonium nitrogen (NH _ 4-N) and nitrate-N (no _ 3-N) were 12.40 ~ 8.18 and 4.22 kg / h ~ (-1) 路a ~ (-1), respectively. The average ratio of ammonium nitrogen to nitrate nitrogen was 1.79.2. The average weighted value of precipitation pH was 5.49 in a month. The frequency of acid rain is 33.93, the average monthly rainfall is 69.4 mm, the average annual precipitation is 832.8 mm, the annual sedimentation fluxes of NH _ 4-N and NO_3~--N are 6.404.05 and 2.35 kgN 路hm ~ (-2) 路a ~ (-1) 路a ~ (-1) respectively, the average ratio of ammonium nitrogen to nitrate nitrogen is 1.61.3. The average annual concentration and annual average annual concentration of NH _ 4-N and DIN in both places are 1.61.3. The concentration of inorganic nitrogen in the two places was lower than that in the suburbs of Chongqing (Shapingba District, Beibei District (Xianmenshan National Forest Park) and Beibei District), and the concentration of inorganic nitrogen in the two places was lower than that in Chongqing suburb (Shapingba District, Beibei District) and Forest area (Xianyushan National Forest Park). The annual deposition fluxes of three kinds of inorganic nitrogen at the two monitoring sites are lower than those of most of the same underlying surface types, respectively, which are higher than those of Haibei and Linzhi, which are less affected by human activities. The comprehensive analysis shows that the concentrations of NH4 -NCO _ 3.-N and DIN in this study area are both in the medium level, and the average annual mean value is at a lower level, but is seriously affected by human activities. Through the analysis of the precipitation in the two places, the backward trajectory analysis is carried out. It is concluded that the precipitation air masses in the two places are mainly from the northwest and southwest, and the precipitation of both places is stronger than that of the oceanic air masses.
【学位授予单位】：重庆三峡学院
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X51

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