南京市大气细颗粒物化学成分分析

为了解南京大气细粒子的污染水平和污染特征,在南京市中心鼓楼和北郊南京信息工程大学校内进行了连续1a、每季度5d的大气气溶胶同步采样。用称重法、离子色谱法和电感耦合等离子质谱法分别测得细颗粒物的质量浓度、水溶性离子和元素组成。结果表明,南京地区PM2.1污染比较严重,水溶性离子是细粒子的重要组分,所测6种离子质量浓度总和分别占市区和北郊PM2.1的46.99％、42.32％。PM2.1中的各离子最高浓度都出现在冬季。NH^＋4与SO^2-4的相关性好,可能主要以（NH4）2SO4形式存在。温度对SOR和NOR的影响显著,温度升高时SOR值增大而NOR显著减小。通过计算NO^-3与SO^2-4的质量比发现,南京市SO2和NOx主要来自于固定源（如煤的燃烧）。分析细颗粒物中元素含量和富集因子结果表明,Pb、As、Zn、Hg、Cu、Cr、Ni元素的人为污染较明显,且北郊的污染重于市区。比较PM2.1和PM3.3中的离子成分发现,SO^2-4、NH^＋4在PM2.1中占据绝对优势,F^-、Cl^-、NO^-2、NO^-3等不在细粒子中占明显优势。从元素组成来看,Pb、Zn在PM2.1细粒子中含量显著,而Ca、Mg、Na等在粗粒子中富集。     

太湖地区冬小麦田与蔬菜地N2O排放对比观测研究

2003年11月8日至2004年6月5日对太湖地区相邻的蔬菜地和稻麦轮作生态系统的冬小麦田,在当季不施肥情况下的N2O排放进行了田间同步对比观测,分析了N2O排放时间变化以及土壤湿度、土壤温度、土壤速效氮含量和农业管理措施对N2O排放的影响。研究结果表明,小麦播种前的耕翻(表层大约7cm土壤旋耕)处理不会明显改变稻麦轮作农田整个旱地阶段的N2O排放总量,但却使小麦生长季初期的N2O排放明显减弱69%(p<0.01,p为相关概率),使小麦生长季后期的N2O排放明显偏高2.6倍(p<0.05),而对其余时间段的N2O排放作用不明显。与长期实行稻麦轮作的旱地阶段农田相比,由稻田改种蔬菜20多年的蔬菜地,其整个观测期的N2O排放总量比免耕处理小麦田同期的排放高85%(p<0.05),比耕翻处理小麦田同期的排放高99%(p<0.01)。蔬菜地N2O排放偏高的原因是土壤速效氮,特别是铵态氮含量明显偏高(p<0.01)。     

MEASUREMENTS OF REACTIVE NITROGEN SPECIES IN THE EASTERN CHINA DURING THE EXPERIMENT PEM-WEST A

Measurements of NO_x(NO+NO_2),HNO_3,particulate nitrate,and total odd nitrogen NO_y were made at Linatmosphere regional background station during the NASA GTE/PEM-WEST A in the fall of 1991.NO_x and Nwere measured using chemiluminescence detectors.HNO_3 and aerosol nitrate(NO_3~-)were collected by a filter systNO_x concentration exhibits a significant diurnal variation:maximum occurring in the evening and postsunrise wpeak occurring following sunrise.Unlike NO_x,NO_y does not show distinct diurnal variations.From the ratiosday/night NO_x concentration and the diurnal cycles of two kinds of weather conditions,it is clear thatphotochemical production of NO_x varies with solar radiation.NO_x is the major component of total odd nitroNO_y and NO_2 is the major portion of NO_x as well.The regional background concentrations of NO_x,NO_y,aerosoltrate(NO_3~-)and HNO_3 range from 4.77 to 7.02 ppb,9.24 to 10.95 ppb,0.33 to 2.38 ppb and 0.31 to 0.97 ppb in a dayaverage,respectively.In the eastern China,the biomass burning is an important local emission source of nitrospecies.The ratios of NO/NO_2,NO_x/NO_y,HNO_3/NO_y,NO_3~-/NO_y and HNO_3/NO_x are also discussed inpaper.     

广州市气溶胶质量谱和水溶性成分谱分析

对2006年9月—2007年1月在广州市采集的气溶胶粒子的质量谱和水溶性成分进行分析表明,广州市各测点的气溶胶质量谱基本呈双峰或三峰分布,细粒子浓度占气溶胶总浓度的四成到六成;在气溶胶水溶性离子成分中,浓度最高的阴离子是SO42-和NO3-,浓度最高的阳离子是NH4+和Na+;各离子多呈三峰或是双峰分布,但不同离子的峰值不尽相同;广州市的粉尘污染逐渐减少,而NH4+浓度迅速增大;相对土壤,只有Na+和NH4+富集度比较大,SO42-和K+有一定富集;相对海洋,F-的富集度非常大,其他离子则无明显富集;Cl-被严重耗损;致酸离子以SO42-为主,NO3-作用较弱些;SO42-和NH4+谱分布有很好的相关性,并且在细粒子和巨粒子粒径范围有共同的来源。     

温带森林土壤溶液溶解性N2O和CO2含量特征及其影响机制

利用陶瓷头土壤溶液收集器采集2006年7月～2007年8月问长白山阔叶红松天然林不同深度(15cm和60 cm)土壤溶液,探讨应用气液萃取平衡-气相色谱法测定森林土壤溶液中溶解性气体N_2O和CO_2浓度的可行性,并利用此方法研究林地不同深度土壤溶液中两种气体含量特征及其影响机理.研究结果显示观测期内林地15 cm和60 cm深度土壤溶液中溶解性CO_2浓度的变化范围分别为5.26～10.71μg·mL~(-1)(C)和3.13～6.16 μg·mL~(-1)(C),溶解性N_2O浓度的变化范围分别为2.44～13.40 ng·mL~(-1)(N)和3.23～27.98 ng·mL~(-1)(N).阔叶红松天然林土壤溶液中溶解性CO_2和N_2O浓度均呈现出明显的季节性变化.春融后的降水促进了土壤溶液中溶解性N_2O产生,尤其在60 cm深度.与60 cm深度相比,林地15 cm深度溶液中溶解性CO_2浓度的季节性变化更明显,尤其在植物生长旺季.逐步回归分析显示,水溶性有机碳含量可以解释林地不同深度溶液中溶解性CO_2浓度变化的29%;水溶性有机氮含量可以解释林地60 cm深度溶解性N_2O浓度变化的34%.因此,水溶性有机碳和有机氮分别是长白山阔叶红松林土壤溶液溶解性CO_2和N_2O形成的重要因子.同时研究结果表明本文实验方法对于测定林地不同深度土壤溶液中溶解性N_2O和CO_2含量均有较好的适用性,连续三次萃取后所获得的气体浓度可有效反映溶液中的实际气体浓度.     

广州冬季大气消光系数的贡献因子研究

2008年1月1～31日和2月6～24日在广州城区每天采集一个PM2.5样品,对样品进行有机碳、元素碳及水溶性离子分析,利用美国IMPROVE能见度方程计算得到广州冬季大气消光系数.结果发现:冬季PM2.5 日均值质量浓度为89.0±53.4/μg·m~(-3),OC(Organics Carban)质量浓度为16.9±11.9μg·m~(-3),EC(Element Carbon)质量浓度为5.9±3.4 μg·m～(-3),水溶性离子总浓度为43.9±23.5μg·m~(-3).冬季大气消光系数均值为342±185 Mm~(-1).广州冬季大气消光系数主要贡献者为(NH_4)_2SO_4、NH_4NO_3、POM(Par-ticular organic matter)、EC和NO_2,对消光系数的贡献率分别为36.3%、14.5%、26.6%、17.4%和5.2%.     

中国酸雨研究综述

回顾了我国开展酸雨研究以来所取得的各方面研究成果,主要包括酸雨的定义、空间分布特征、化学特征、影响酸雨pH值的因素、酸雨对生态社会的影响以及酸雨控制的对策和方法6个方面。研究表明,海洋降水pH值以4.8、内陆降水以5.0作为酸雨的界限更为合理;我国酸雨空间分布存在明显的地域差异,南方酸雨比北方严重,且以城市为中心分布;我国降水中总离子浓度很高,酸雨是典型的硫酸性酸雨,降水酸度与(SO42- NO3-)/(NH4 Ca2 )的浓度比值有着高度的正相关;酸雨的形成不仅仅取决于酸性物质的排放,还与酸性物质的迁移和扩散、土壤的性质、大气中的氨、大气颗粒物及其缓冲能力和气象条件有关;酸雨对生态系统、建筑物和人体健康都造成了严重危害,我国酸雨还有进一步加重的趋势,因此必须进一步加强和发展酸雨控制的对策和方法。     

Chemical characterization of wet precipitation events and deposition of pollutants in coal mining region,India

The present study investigated the chemical composition of wet atmospheric precipitation in India’s richest coal mining belt. Total 418 samples were collected on event basis at six sites from July to October in 2003 and May to October in 2004 and analysed for pH, EC, F⁻, Cl⁻, , , Ca²⁺, Mg²⁺, Na⁺, K⁺ and . The average pH value (5.7) of the rainwater of the investigated area is alkaline in nature. However, the temporal pH variation showed the alkaline nature during the early phase of monsoonal rainfall but it trends towards acidic during the late and high rainfall periods. The rainwater chemistry of the region showed high contribution of Ca²⁺ (47%) and (21%) in cations and (55%) and Cl⁻ (23%) in anionic abundance. The high non seas salt fraction (nss) of Ca²⁺ (99%) and Mg²⁺ (96%) suggests crustal source of the ions, while the high nss (96%) and high ratio signifying the impact of anthropogenic sources and the source of the acidity. The ratio of varies from 0.03 to 3.23 with the average value of 0.84 suggesting that Ca²⁺ and play a major role in neutralization processes. The assessment of the wet ionic deposition rates shows no any specific trend, however Ca²⁺ deposition rate was highest followed by and _.     

内蒙古草原温室气体排放日变化规律研究

采用静态值－气相色谱法研究内蒙古草原温室气体N2O、CO2、CH4与大气交换的日变化规律。CO2日排放变化形式基本相同，和大气交换的总结果是向大气排放，影响草原N2O排放日变化形式的关键是土壤含水量和表层土壤理化特性，日温变化主要影响其日变化强度；影响草原CH4日变化形式的关键因子是土壤水分和供氧状况，而温度和植物的生长状况则影响吸收强度，利用内蒙古草原温室气候排放相对固定的日变化形式，可以对相同生产季内每周1次的观测结果进行矫正。     

塔克拉玛干沙漠腹地流沙下垫面土壤呼吸特征及影响因素分析

通过LI-COR8100A土壤碳通量观测系统分别于2013年1月、5月、10月和11月进行了塔克拉玛干沙漠腹地塔中流沙下垫面土壤呼吸速率测定试验,并分析了相应的土壤水热因子对呼吸速率的影响。结果表明:塔克拉玛干沙漠腹地土壤呼吸速率整体偏低,但具有明显的昼夜波动性和季节变化特征。研究区流沙土壤中可能存在的无机碳过程是导致夜间及凌晨的土壤呼吸速率为负值,白天为正值的主要原因。不同时段的土壤呼吸速率(Rs)分别与土壤表层0~5 cm平均土壤温度(T)和湿度(W)间存在较为同步的昼夜变化趋势且具有良好的回归关系。相对于单因素影响的回归分析,土壤温、湿度的协同作用能够从整体角度更好地解释土壤呼吸速率的变化情况。回归方程Rs=a+bT+cW和Rs=a+bT+cW+dTW可解释不同时段土壤呼吸速率76.0%以上的变化情况。这说明土壤温、湿度是控制土壤呼吸速率的主要环境因子。沙漠腹地土壤极低的水分条件成为土壤呼吸的限制性因子,呼吸速率对于作为限制性因子的土壤湿度的变化响应则更加直接,而对于土壤温度变化的敏感性就有所下降,导致土壤呼吸速率与土壤温度回归关系出现明显的时滞环现象。     

Characteristics of Aerosol Pollution Under Different Visibility Conditions in Winter in a Coastal Mega-City in China

To investigate chemical profiles and formation mechanisms of aerosol particles in winter haze events,comprehensive measurements including hourly concentrations of PM2.5 and water-soluble inorganic ions and related gasphase precursors were conducted via an online monitoring system from January to March of 2016 in Shenzhen, a coastal mega-city in south China. In this study, high concentrations of PM2.5, NO2 and lower levels of O3 were observed during haze periods in comparison with clear days(Visibility15 km). The major secondary ionic species were NH+4、NO-3 and SO2-4, which varied significantly on haze and clear days. The ratio of NO-3/SO2-4 in haze days was greater than that on clear days and tended to be larger when air pollution became more serious. At the same time, compared with previous studies, it has been found that the ratio has been increasing gradually in Shenzhen, indicating that the motor vehicle exhaust emissions have a more and more important impact on air quality in Shenzhen. Sulfur oxidation rate(SOR) and nitrogen oxidation rate(NOR) was higher during the haze period than that in clean days, indicating efficient gas to particle conversion. Further analysis shows that high concentrations of sulfate might be explained by aqueous oxidation,but gas-phase reactions might dominate nitrate formation. This study also highlights that wintertime nitrate formation can be an important contributor to aerosol particles, especially during haze periods.     

南京冬季辐射雾和平流辐射雾的化学特征差异

利用2006和2007年冬季南京雾外场试验中取得的雾水离子成分资料,分析了雾水化学组分特征,探讨了雾水酸度来源及辐射雾和平流辐射雾的化学特征差异。结果表明,南京冬季雾水中总离子浓度偏高,浓度最高的3种离子成份是SO^-24、NH^＋4和Ca^2＋,但雾水酸性不强,碱性离子成分的中和作用是pH值较高的原因。平流辐射雾中雾水离子总浓度约为辐射雾的2.2倍,平流辐射雾中浓度最高的阳离子为NH^＋4,辐射雾中为Ca^2＋。     

Mitigation options for methane, nitrous oxide and nitric oxide emissions from agricultural ecosystems

1.IntroductionNitrousoxide(N,O)andmethane(CH.)arethemostimportantgreenhousegassesintheatmospherewithitscontributiontoglobalwarmingjustlowerthanCO2.Theirconcentrationsinatmospherehavebeennotedtoincreasecurrentlyattherateof0.25%yr--'andl.02%yr',respectively(IPCC,1995).Atpresent,theincreaseofNZOandCH4intheatmospherehasbeenestimatedtoaccountfor20--25%oftheglobalwarming(FAO&IAEA,1992;Bailes&Bridges,1992).NOdoesnotabsorbradiationdirectlyintheatmosphere,buttheincreasingconcentrationofNOmay…     

The heterogeneous formation of N2O in air containing NO2, O3 and NH3

In a nighttime system and under relatively dry conditions (about 15 ppm H₂O), the reaction mixture of NO₂, O₃, and NH₃ in purified air turns out to result in the formation of nitrous oxide (N₂O). The experiments were performed in a continuous stirred flow reactor, in the concentration region of 0.02–2 ppm.N₂O is thought to arise through the heterogeneous reaction of gaseous N₂O₅ and absorbed NH₃ at the wall of the reaction vessel % MathType!MTEF!2!1!+-% feaafeart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqaqpepeea0xe9qqVa0l% b9peea0lb9sq-JfrVkFHe9peea0dXdarVe0Fb9pgea0xa9pue9Fve9% Ffc8meGabaqaciGacaGaaeqabaWaaeaaeaaakeaatCvAUfKttLeary% qr1ngBPrgaiuaacqWFOaakcqWFobGtcqWFibasdaWgaaWcbaGae83m% amdabeaakiab-LcaPmaaBaaaleaacqWFHbqyaeqaaOGaey4kaSIaai% ikaiab-5eaonaaBaaaleaacqWFYaGmaeqaaOGae83ta80aaSbaaSqa% aiab-vda1aqabaGccaGGPaWaaSbaaSqaaiaadEgaaeqaaOGaeyOKH4% Qae8Nta40aaSbaaSqaaiab-jdaYaqabaGccqWFpbWtcqGHRaWkcqWF% ibascqWFobGtcqWFpbWtdaWgaaWcbaGae83mamdabeaakiabgUcaRi% ab-HeainaaBaaaleaacqWFYaGmaeqaaOGae83ta8eaaa!59AC!\[(NH_3 )_a + (N_2 O_5 )_g \to N_2 O + HNO_3 + H_2 O\]In principle, there is competition between this reaction and that of adsorbed H₂O with N₂O₅, resulting in the formation of HNO₃. At high water concentrations (RH>75%), no formation of N₂O was found. Although the rate constant of adsorbed NH₃ with gaseous N₂O₅ is much larger than that of the reaction of adsorbed H₂O with gaseous N₂O₅, the significance of the observed N₂O formation for the outside atmosphere is thought to be dependent on the adsorption properties of H₂O and NH₃ on a surface. A number of NH₃ and H₂O adsorption measurements on several materials are discussed.     

影响农田氧化亚氮排放过程的土壤因素

土壤理化特性是影响农田氧化亚氮(N2O)产生和排放的重要因素.作者主要讨论了土壤微生物、土壤质地、土壤中化学物质、土壤温度和土壤pH值等对农田N2O的影响.继续深入研究这些因素对农田N2O排放的综合影响和机理以及与其排放量之间的数量关系应是未来的研究重点.为准确估计区域乃至全球范围的农田N2O排放总量,对农田N2O排放模型中关键土壤参数的确定尤为重要.     

The Characteristics and Controlling Factors of Water and Heat Exchanges over the Alpine Wetland in the East of the Qinghai–Tibet Plateau

Alpine wetland is one of the typical underlying surfaces on the Qinghai–Tibet Plateau. It plays a crucial role in runoff regulation. Investigations on the mechanisms of water and heat exchanges are necessary to understand the land surface processes over the alpine wetland. This study explores the characteristics of hydro-meteorological factors with in situ observations and uses the Community Land Model 5 to identify the main factors controlling water and heat exchanges.Latent heat flux and therm...     

Net radiation — soil heat flux relations as influenced by soil water content variations

Net radiation, soil heat flux, incoming and reflected solar radiation, and soil water content were measured during several clear day periods following approximate 10-cm applications of water to loam soils at Phoenix, Arizona, and at Sidney, Montana. The regression of soil heat flux on net radiation changed significantly as the soil dried, with the difference between them being a linear function of the volumetric soil water content of the uppermost 2 to 4 cm of soil. The net radiation-soil heat flux difference for soil in an air-dry state was only about one-half of what it was on the day after irrigation. Techniques discussed allow evaluation of what the net radiation-soil heat flux difference would be under conditions of no surface saturation deficit at any time of year from measurements of net solar radiation, soil water content, and air temperature, thereby improving the utility of many evaporation models. The data also indicate that water content measurements may be replaced by more easily measured soil albedo.     

南京北郊冬季大气S0_2、N0_2和0_3的变化特征

利用差分吸收光谱仪DOAS(differential optical absorption spectroscopy),对2007年11月-2008年1月南京北郊大气SO_2、NO_2和O_3进行了观测.结合Parsivel降水粒子谱仪和自动气象站的资料,对冬季大气污染气体的浓度变化规律及降水和风速风向对其的影响进行了分析.结果表明,南京北郊大气SO_2浓度较高,呈明显双峰特征,分别在12时(北京时,下同)和00时达最大,受附近排放源的影响最大,东风及南风时比静风时SO_2浓度更高.降水对SO_2湿清除效果明显,清除系数平均为0.168h~(-1).NO_2气体呈明显单峰特征,在18时达最高值.南京北郊是NO_2源区之一,主要受附近高速公路汽车尾气排放源的影响.静风时NO_2浓度最高.O_3浓度受NO_2的影响较明显.O_3日变化呈单峰特征,在15时达最大值,静风时O_3浓度最低.降水对O_3的间接影响较明显,在降水时,白天由于太阳辐射较弱,O_3浓度降低;夜晚NO浓度较低,使得O_3浓度升高.     

半干旱草原温室气体排放/吸收与环境因子的关系研究

静态箱—气相色谱法对内蒙古半干旱草原连续两年的实验观测研究结果表明，内蒙古草原是大气CO2和N2O的排放源，和CH4的汇。在植物生长不同季节，草原生态系统排放／吸收温室气体CO2、CH4和N2O的日变化形式各有不同，其中在植物生长旺季日变化形式最具特征。三种温室气体的季节排放／吸收高峰主要出现在土壤湿度较大的春融期和降雨较为集中时期。对所有草原植物生长季节，CO2净排放日变化形式均为白天出现排放低值，夜间出现排放高值。较高的温度有利于CO2排放，地上生物量决定着光合吸收CO2量值的高低。影响半干旱草原吸收CH4和排放N2O日变化形式的关键是土壤台水量和供氧状况，日温变化则主要影响日变化强度。吸收CH4和排放N2O的季节变化与土壤湿度季节变化分别呈线性反、正相关，相关系数均在0．4-0．6之间。自由放牧使CO2、N2O和CH4交换速率日较差降低，同时使N2O和CH4年度排放／吸收量减少和CO2年度排放量增加。     

土壤含水量与温度对羊草、大针茅典型草原土壤—植物系统温室气体收支影响的初步研究

本研究首次以我国内蒙古典型草原生态系统为研究对象,以密闭箱法对土壤－植物系统与大气间Ｎ２Ｏ和ＣＨ４气体交换进行了原位观测研究,通过结合实验室模拟实验研究表明,土壤含水量和温度对草原土壤－植物系统温室气体（Ｎ２Ｏ和ＣＨ４）排放通量有着重要的影响。在一定范围内,土壤含水量增加促进草原生态系统Ｎ２Ｏ排放和ＣＨ４吸收作用。温度升高促进草原生态系统Ｎ２Ｏ排放,但对ＣＨ４吸收的影响作用不明显。