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乌鲁木齐市及周边地区大气活性氮特征及其干湿沉降通量
王晓丽
学位类型硕士
导师刘学军
2015
学位授予单位中国科学院大学
学位授予地点北京
学位专业环境科学
关键词乌鲁木齐市 大气活性氮 二次气溶胶 15n特征值
摘要工业革命以来,化石燃料燃烧、过量施肥和集约畜牧业等人类活动加快了大气活性氮的排放,导致全球氮沉降水平持续升高。氮沉降的增加带来了一系列严重的生态问题,如水体生态系统富营养化、生物多样性降低、土壤酸化和森林衰退等。本文旨在通过对乌鲁木齐市及周边地区大气活性氮组分的监测,定量大气活性氮浓度动态及氮素干、湿沉降通量,并初步分析了不同人为排放源附近监测点的大气活性氮15N同位素特征值,为科学评价乌鲁木齐地区大气活性氮污染现状及氮沉降通量提供依据。论文主要结果如下: 1. 各采样点大气活性氮NH3、NO2、大气颗粒态(pNH4+和pNO3-)浓度表现出显著差异,其中NH3浓度以养殖场猪舍内最高(405.8 µg m-3),南山背景区最低(8.22 µg m-3);NO2排放浓度在交通区最大达63.3 µg m-3;活性氮浓度在不同区域呈现出显著的季节性变化趋势,说明其受人类活动强度影响较大。 2. 各采样点NH3浓度与颗粒态pNH4+浓度存在负相关关系,NO2浓度与颗粒态pNO3-浓度除土肥所采样点不相关外,其余各点均表现出显著的正相关关系;各采样点大气颗粒态pNH4+和颗粒态pNO3-均表现出极显著的正相关。 3. 各采样点大气颗粒物中主要的水溶性无机离子有K+、Na+、NH4+、Ca2+、Mg2+、Cl-、NO3-、SO42-等,以二次气溶胶组分SAN (NH4+、NO3-、SO42-)为主,其在总水溶性无机离子(TWSII)中所占比重较大且有明显的季节变化趋势;通过对二次组分间相关性分析得出其主要以(NH4)2SO4或NH4HSO4和NH4NO3形式存在的,表明大气活性氮影响二次气溶胶的形成;乌鲁木齐市NO3-/SO42-的比值在0.22~0.48,平均值为0.36,说明固定源(含硫燃料的燃烧)仍是乌鲁木齐大气二次气溶胶的主要来源。 4. 乌鲁木齐市区、土肥所试验基地、市郊南山森林采样点大气氮素沉降通量分别为15.7、22.0、7.48 kg N ha-1 yr-1,均以NH3-N沉降为主,乌鲁木齐市区、土肥所试验基地采样点均表现为晚秋至早春季节氮沉降量最大,南山采样点大气氮素沉降量恰好相反;市区NH4-N和NO3-N湿沉降通量为分别为3.30和2.01 kg N ha-1 yr-1,总的氮素沉降量约为21.0 kg N ha-1 yr-1。 5. 各排放源周边监测点大气NH3的δ15N值均为负值而NO2的δ15N值以正值为主,具体结果为:NH3的δ15N值以市郊南山森林监测点(自然源为主,-4.20‰) > 土肥所试验基地(农田排放源,平均-7.04‰)和生地所(交通源,-7.89‰)> 五一农场养猪场猪舍内(动物排放源,-19.2‰);而NO2的δ15N值主以火电厂监测点(31.1‰)> 八钢工业源监测点(23.6‰)> 生地所交通源(-7.97‰)。
其他摘要Since the industrial revolution, anthropogenic reactive nitrogen (N) emissions have been greatly increased mainly by over-fertilization, fossil fuel use and intensive animal husbandry and they lead to a continual increase in atmospheric N deposition worldwide. Nitrogen deposition can cause a series of serious ecological and environemntal problems, such as eutrophication in water bodies, biodiversity decline, soil acidification and forest degradation. This study aimed to quantify atmospheric reactive N concentration, wet and dry N deposition as well as the primary characteristics of 15N stable isotopes of gaseous N in Urumqi city and its surrounding areas in order to obtain basic information on evaluating the present atmospheric reactive N pollution status in Urumqi. The main results are summarized as follows: 1. Mean concentrations of ammonia (NH3), nitrogen dioxide (NO2), particulate ammonium (pNH4+) and nitrate (pNO3-) varied greatly across different regions. The highest NH3 concentration was 405.8 g m-3 at a swine farm site, the lowest NH3 concentrations was 8.22 µg m-3 at Nanshan (NS) forest site; the highest NO2 concentration was 63.3 µg m-3 at a traffic site in downtown of Urumqi. Atmospheric reactive N concentrations showed obvious seasonal variations in the study area. These results suggest that atmospheric reactive N concentrations are closely related to anthropogenic reactive N emissions (including emissions from animal husbandry and traffic vehicles). 2. Ammonia concentration showed negative correlation with pNH4+ at the sampling sites. The NO2 concentration had a significant positive correlation with pNO3- except for the farm site (Anningqu) during the study period. Particulate NH4+ showed high positive correlation with pNO3-. 3. The main water-soluble ions in particulate matter at sampling sites included K+, Na+, NH4+, Ca2+, Mg2+, Cl-, NO3- and SO42-. The NH4+, NO3- and SO42- were major water-soluble ions, which were mainly in the forms of secondary aerosols such as (NH4)2SO4, NH4HSO4 and NH4NO3 through the correlation analysis. The ratios of NO3-/SO42- ranged from 0.22 to 0.48 and the mean value was 0.36 in Urumqi, indicating that the fixed source (containing sulfur fuel combustion) is still the main source of secondary aerosols in the atmosphere in Urumqi. 4. Atmospheic dry N deposition, measured by the inferential method was 15.7, 22.0, 7.48 kg N ha-1 yr-1 at downtown of Urumqi, Anningqu, NS, respectively. Reduced N (NH3 and pNH4+) deposition is the main form at the sampling sites. Highest dry deposition was found from late autumn to early spring next year at downtown of Urumqi and Anningqu sites. The opposite trend of dry deposition was observed at NS site. Total annual inorganic N deposition (wet plus dry) was approximately 21.0 kg N ha-1, with 76% as dry N deposition in Urumqi. 5. The δ15N values of NH3 at sites around all sources were negative; while the δ15N values of NO2 were mostly positive at the sampling sites. Averaged δ15N values of NH3 followed by the sequences of NS forest site (-4.20‰) > cropland site (-7.04‰) and traffic site (-7.89‰) > swine farm site (-19.2‰). The mean δ15N values of NO2 ranked by the order of thermal powerplant site (31.1‰) > industrial source site (23.6‰) > traffic site (7.97‰), respectively.
学科领域环境科学
语种中文
文献类型学位论文
条目标识符http://ir.xjlas.org/handle/365004/14672
专题研究系统_荒漠环境研究室
作者单位中科院新疆生态与地理研究所
推荐引用方式
GB/T 7714
王晓丽. 乌鲁木齐市及周边地区大气活性氮特征及其干湿沉降通量[D]. 北京. 中国科学院大学,2015.
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