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新疆典型生态系统大气颗粒物与活性氮组分特征及其沉降通量
宋韦
学位类型博士
导师刘学军 ; 田长彦
2015
学位授予单位中国科学院大学
学位授予地点北京
学位专业生态学
关键词Pm10 Pm2.5 大气活性氮 煤改气 二次气溶胶
摘要大气污染是我国当前面临的最严峻的环境问题之一,而大气可吸入颗粒物(PM10)、细颗粒物(PM2.5)以及NH3和NOx等大气活性氮组分均是重要的大气污染物。大气颗粒物(PM10、PM2.5)和大气活性氮都会对人类健康和生态环境造成危害。由于新疆特殊的自然环境,形成了山地、绿洲、荒漠三大主要生态区,因此选择草原、农田、城市、沙漠、荒漠与绿洲交错带和森林等典型生态系统为研究对象,能够整体上反映新疆的大气颗粒物(PM10为主、PM2.5为辅)污染及氮素沉降通量状况。本研究以中科院野外实验站为依托,通过多年多点采样及影响因素分析,来揭示新疆不同生态系统颗粒物的时空变异特征、大气活性氮干湿沉降通量和大气活性氮排放对大气颗粒物污染的影响。为全面了解新疆典型生态系统大气颗粒物和大气活性氮污染状况提供系统的数据资料,为新疆制定有效的颗粒物和大气活性氮污染控制对策提供理论依据。主要研究结果如下: 1. 在草原,森林,城市,农田,荒漠绿洲交错带和沙漠生态系统中,PM10的年均浓度分别为26.1、36.0、208、359、443和454 μg m-3。在长期采样点,PM10的浓度在年际间没有显著的差异。在各生态系统中,PM10的浓度存在显著的季节变化,在草原、森林、农田、荒漠与绿洲交错带和沙漠生态系统中,PM10的浓度在春夏季较高,在秋冬季较低;但是在城市生态系统,PM10的浓度在冬季最高,夏季最低。在南疆(天山以南)的采样点,PM10的浓度与风速呈显著的正相关。在北疆(天山以北)的采样点,PM10的浓度与温度呈极显著的负相关,与风速呈极显著的负相关。大气可吸入颗粒物(PM10)中阴阳离子和金属元素的浓度在不同生态系统间存在明显的时空差异。 2. 乌鲁木齐市PM2.5的污染程度非常严重,2010,2011和2012年PM2.5的年均浓度分别为152,171和87 μg m-3,是国家二级标准(年均35 μg m-3)的4.34,4.89和2.48倍。乌鲁木齐PM2.5的浓度存在显著的(p<0.05)季节变化,冬季浓度最高,夏季浓度最低,其春、夏、秋和冬季的浓度分别为114, 84.8, 118 和323 µg m-3。PM2.5中水溶性离子的浓度(NO3-、NH4+、SO42-、Cl-、Na+、K+、Mg2+和Ca2+)也存在着显著的季节变化,NO3-、NH4+、SO42-、Cl-、Na+、K+和Mg2+的浓度是冬季显著高于其他3个季节,而Ca2+的浓度则是春季最高。二次颗粒物的质量浓度和其在PM2.5中的比例都是冬季最高,夏季最低。二次颗粒物在PM2.5中的比例有俩个转折点,即每年的4月中旬后迅速降低,而在每年的10月中旬后迅速升高。进一步研究显示,冬季供暖“煤改气”行动可以显著降低了乌鲁木齐PM2.5浓度, 发现在“煤改气”初步完成的2013年1月(120 μg m-3)和全部完成的2014年1月份(78.9 μg m-3)乌鲁木齐PM2.5的月均浓度分别比2011和2012年同期(平均322.5 μg m-3)降低63%和76%。同时,“煤改气”也显著降低了PM2.5中水溶性无机离子(NH4+、NO3-、SO42-、Cl-、Na+、Mg2+和Ca2+)和金属元素(As、Cr、Mn、Ni、Cu、Cd、Pb和Al)浓度。 3. 新疆典型生态系统13个采样点大气可吸入颗粒物(PM10)的沉降通量变化范围为36.9-1316 kg ha-1 yr-1。草原、森林、城市、农田、荒漠与绿洲交错带和沙漠生态系统的PM10沉降通量分别为36.9、49.9、288、486、614和629 kg ha-1 yr-1。Cl-、Na+、K+、SO42-、Mg2+和Ca2+在草原和森林生态系统沉降量较低,除K+外,其他五种离子在沙漠生态系统沉降通量最高,K+在城市生态系统沉降通量最高。大气可吸入颗粒物(PM10)中As、Ni、Zn、Cd和Al的沉降通量在城市生态系统中最高,Mn、Li、Cr、Cu和Pb在城市生态系统的沉降通量相对较高,Mn和Li在城市生态系统的沉降通量略低于在沙漠生态系统的沉降通量,Cr、Cu和Pb在城市生态系统的沉降通量略低于在荒漠与绿洲交错带的沉降通量。 4. 在不同的生态系统NH3的浓度为草原生态系统(2.23 μg m-3)<沙漠生态系统(3.47 μg m-3)<森林生态系统(5.37 μg m-3)<荒漠与绿洲交错带(8.59 μg m-3)<城市生态系统(13.1 μg m-3)<农田生态系统(15.6 μg m-3)。在不同的生态系统NO2的浓度为草原生态系统(1.93 μg m-3)<森林生态系统(5.98 μg m-3)<沙漠生态系统(8.03 μg m-3)<荒漠与绿洲交错带(13.1 μg m-3)<农田生态系统(15.5 μg m-3)<城市生态系统(48.2 μg m-3)。长期采样点出吐鲁番2010年NH3年均浓度(4.29 μg m-3)显著低于2011(8.50 μg m-3)和2012年(7.88 μg m-3)NH3的年均浓度外,其他长期采样点NH3年均浓度没有显著的年际差异;长期采样点的NO2的年均浓度也没有显著的年际差异。NH3存在显著的季节差异,冬季浓度要远低于其他三个季节。NO2也存在显著的季节差异,在草原、森林和沙漠冬季浓度最低,在城市、农田和荒漠与绿洲交错带冬季浓度最高。在农田、荒漠与绿洲交错带、沙漠、森林、草原和城市生态系统水溶性离子在PM10中所占的比例分别为9.40、11.9、21.0、29.1、29.2和35.5%,二次颗粒物所占比例分别为4.70、7.07、9.42、18.2、15.1和25.5%。二次颗粒物(NH4+、NO3-和SO42-之和)在PM10中所占比例也是冬季最高,春夏季较低。 5. 各采样点大气活性氮沉降通量变化范围为1.82-41.5 kg N ha-1 yr-1,沙漠、草原、森林、荒漠与绿洲交错带、农田和城市生态系统的大气活性氮沉降通量分别为1.82、6.22、10.5、13.0、13.4和38.5 kg N ha-1 yr-1,其中草原和森林生态系统的大气活性氮沉降以沉降为主,约占大气活性氮沉降总量的64%,而沙漠生态系统、荒漠与绿洲交错带、农田生态系统和城市生态系统氮素主要以干沉降为主,约占总沉降通量的80.0-97.1%。
其他摘要Air pollution is one of the most serious environmental problems in China, and inhalable particulate matter smaller than 10 μm (PM10), fine particulate matter smaller than 2.5 μm (PM2.5) and atmospheric reactive nitrogen species such as NH3 and NOx are important atmospheric pollutants. PM10 and PM2.5 and atmospheric reactive nitrogen will be harmful to human health and ecological environment. Due to the special natural environment, Xinjiang consists of three major ecological zones of mountains, oasis and deserts. In order to reflect pollution status of particulate matter (mainly PM10 and secondary aerosols such as PM2.5) and reactive nitrogen in the whole Xinjiang region, grassland, farmland, urban, desert, desert and oasis ecotone and forest ecosystems must be selected. Therefore, based on field experimental stations in the Chinese Academy of sciences and through multi-year and multi-sampling and analysis of influencing factors, we revealed the spatial and temporal variation of atmospheric particulate matter in different ecosystems. And we also clarified the fluxes of atmospheric reactive nitrogen dry and wet deposition and the influence of atmospheric reactive nitrogen emissions to the atmosphere of particulate matter pollution. This study can provide systematic data for understanding atmospheric particles and atmospheric reactive nitrogen pollution in the typical region of Xinjiang. It also can provide theoretical basis for Xinjiang government to make the effective control measures for atmospheric particles and atmospheric reactive nitrogen pollution. The main results are summarized as follows: 1. The annual average concentrations of PM10 were 26.1, 36.0, 208, 359, 443 and 454 μg m-3 at monitoring sites in grassland, forest, urban, farmland, desert oasis ecotone and desert ecosystems, respectively. There was no significant difference in the annual concentration of PM10 in the long-term sampling sites. PM10 concentrations had an obvious seasonal variation in different ecosystems. PM10 concentrations were higher in spring and summer and lower in autumn and winter in grassland, forest, farmland, desert and oasis ecotone and desert ecosystems. And PM10 concentrations were highest in winter and lowest in summer in urban ecosystem. There was a significant positive correlation between PM10 concentration and wind speed in the south of Xinjiang (South of Tianshan Mountains), however, significant negative correlations were observed between PM10 concentration and temperature and PM10 concentration and wind speed in the north of Xinjiang (North of Tianshan Mountains). The concentrations of ions and metal elements in PM10 had significant spatio-temporal variations in the different ecosystems. 2. The annual mean concentrations of PM2.5 were 152, 171 and 87 μg m-3 in 2010, 2011 and 2012 in Urumqi, which were 4.34, 4.89 and 2.48 times higher than the Chinese second class Ambient Air Quality Standard (annual mean concentrations of 35 μg m-3). PM2.5 concentrations had significant (p<0.05) seasonal variation, which were highest in winter and lowest in summer. The concentrations of PM2.5 were 114, 84.8, 118 and 323 μg m-3 in spring, summer, autumn and winter, respectively. The concentration of water soluble ions (NO3- , NH4+, SO42-, Cl-, Na+, K+, Mg2+ and Ca2+) in PM2.5 also had significant (p<0.05) seasonal variation. The concentrations of NO3- , NH4+, SO42-, Cl-, Na+, K+ and Mg2+ were higher in winter than in other three seasons. However, Ca2+ concentration was highest in spring. The mass concentrations of secondary particles and its proportion in PM2.5 were highest in winter and lowest in summer. The proportion of secondary particles in PM2.5 had two turning points which rapidly decreased after the annual mid-April and increased rapidly after the annual mid-October. Further research showed that the action of “shifting from coal to natural gas” in winter could significantly reduce concentrations of PM2.5 in Urumqi. Compared with the same period in 2011 and 2012 (mean concentration of 322.5 μg m-3), PM2.5 concentrations in January 2013 (120 μg m-3) and in January 2014 (78.9 μg m-3) were decreased 63% and 76%, respectively. This was resulted from the effects of the action of “shifting from coal to natural gas”, which was initially and totally completed in January 2013 and 2014. Meanwhile, “Shifting from coal to natural gas” also significantly reduced the concentrations of water soluble ions (NH4+, NO3-, SO42-, Cl-, Na+, Mg2+ and Ca2+) and metal elements (As, Cr, Mn, Ni, Cu, Cd, Pb and Al). 3. PM10 deposition fluxes were ranged from 36.9 to 1316 kg ha-1 yr-1 at all the thirteen sampling sites in the typical region of Xinjiang. PM10 deposition fluxes were 36.9, 49.9, 288, 486, 614 and 629 kg ha-1 yr-1 in grassland, forest, urban, farmland, desert and oasis and desert ecosystems, respectively. Cl-, Na+, K+, SO42-, Mg2+ and Ca2+ had low deposition fluxes in grassland and forest ecosystems. Cl-, Na+, SO42-, Mg2+ and Ca2+ had highest deposition fluxes in desert ecosystem. However, K+ had highest deposition fluxes in urban ecosystem. The deposition fluxes of As, Ni, Zn, Cd and Al in PM10 were highest in urban ecosystem. The deposition fluxes of Mn, Li, Cr, Cu and Pb were relative higher in urban ecosystem. The deposition fluxes of Mn and Li in urban ecosystem were lower than in desert ecosystem. The deposition fluxes of Cr, Cu and Pb in urban ecosystem were lower than in desert oasis ecotone ecosystem. 4. In different ecosystems, NH3 concentrations were orderly: grassland ecosystem (2.23 μg m-3)
学科领域生态学
语种中文
文献类型学位论文
条目标识符http://ir.xjlas.org/handle/365004/14606
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
宋韦. 新疆典型生态系统大气颗粒物与活性氮组分特征及其沉降通量[D]. 北京. 中国科学院大学,2015.
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