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1.
Daily measurements the atmospheric cocnentrations of HNO3, NO3-, NO2, SO2, SO42−, NH4+, and several trace metals were made at the University of Michigan Biological Station over a 124-day period during the 1984–1985 winter. The composition of the daily precipitation was also determined. The relative contributions of scavenged NO3 and HNO3 to the precipitation was estimated by assuming that the NO3 scavenging ratio was the same as that of trace metals with a similar particle size. Similarly, the SO42− and SO2 contributions were based on the scavenging ratios of NH4+ and trace metals. On this basis, it was determined that the event median NO3 and HNO3 scavenging ratios were 500 and 3500, respectively. HNO3 scavenging accounted for 83% of the total scavenged NO3. Scavenging of SO42− accounted for all the snow SO42− in 67% of the events. In the remaining events, some SO2 was scavenged, with a median scavenging ratio of 219. Overall, 67% of the snowfall acidity appeared to be due to HNO3 scavenging. Backward air-mass trajectories that were calculated for each event were used to determine the general source regions of the acidic species. Snow associated with air masses from the south and west accounted for 81 and 75% of the deposited NO3 and SO42−, respectively.  相似文献   

2.
The concentrations of aerosols (NH4NO3, (NH4)2SO4 and NH4Cl) and of gases (HCl(g), HNO3(g), NH3(g) were determined by denuder methods under different conditions (in the absence of fog, before, during and after fog events). At this site situated in an urban region, high concentrations of the gaseous strong acids HCl(g) and HNO3(g) are observed. NH4Cl and NH4NO3 aerosols represent a major fraction of the Cl and NO3 aerosols (<2.4 μm)collected by denuders. During a fog event, very high concentrations of SO42− were found in small aerosols, which are attributed to the aqueous phase oxidation of SO2 under the influence of high pH due to the presence of NH3. Differences in SO42− concentrations measured in aerosols (<2.4 μm) and in fog droplets were probably due to mass-transport limitations of the SO2 oxidation. Ammonium sulfate aerosols represent in some cases a significant fraction of the total S present (SO2(g) + SO42−. Soluble aerosols and gases contribute to the composition of fogwater and are released again after fog dissipation.  相似文献   

3.
应用扩散管测量霾污染期间大气氮硫化合物浓度的方法   总被引:4,自引:2,他引:2  
活性氮和硫化合物在大气颗粒物形成过程中扮演重要角色,但对它们气相/颗粒相的同步观测结果比较缺乏.本研究尝试基于扩散管的DELTA系统测量氮和硫化合物短时累积浓度,以期捕捉它们在霾污染期间的演变规律.结果表明,DELTA系统收集气态污染物的扩散管中以及颗粒物滤膜上NH_4~+和NO-3空白干扰较小,适用于研究NH_3、HNO_3、NH_4~+和NO-3的日均浓度,可以作为城市环境空气质量监测参数的有效补充;但采样系统中SO_2-4背景含量较高,仅适合监测48 h以上时间尺度的SO_2浓度和周~月尺度SO_2-4浓度,用于大气硫沉降观测.北京2016年5月9日~6月7日观测期间,大气NH_3、HNO_3、NH_4~+和NO-3浓度具有明显的逐日演变规律,呈现出随着风向转变而发生周期性波动的典型特征;这些含氮污染物与PM_(2.5)、CO、SO_2和NO_2浓度的变化规律一致,其来源可能与化石燃料燃烧源有关.污染天NH_3、HNO_3、NH_4~+和NO-3浓度约为清洁天的2倍,但还原性氮和氧化性氮的相态分布在清洁天和污染天无明显差异;整个观测期间,HNO_3/NO-3约为1.2,NH_3/NH_4~+为4.5,春夏之交较高的温度有利于活性氮在气粒平衡过程中偏向于气态形式存在.  相似文献   

4.
Wet precipitation-only samplers were used to collect wet deposition at two sites in the Athens basin, Greece for the period March 1986–February 1987.Concentrations of major cations (H+, NH+4, Na+, K+, Ca2+ and Mg2+) and major anions (Cl, NO3 and SO2−4) were determined for the first time in rainwater samples in Greece. Bicarbonate concentrations were calculated. The relative importance of natural and anthropogenic sources were estimated by a chemical balance. The majority of rain collected has a neutral or alkaline character. Acidity was due to the presence of H2SO4 and HNO3. The statistical analysis of the correlation between the concentration of chemical species confirm the influence of natural and anthropogenic sources. In all samples, SO2−4 concentrations exceed NO3 concentrations despite the dominance of low S oil burning in the region. The wet flux of S was calculatd to be 0.34 gm−2a−1.  相似文献   

5.
Fog, aerosol, and gas samples were collected during the winter of 1986 at Riverside, California. The dominant components of the aerosol were NH4+, NO3, and SO42−. Gaseous NH3 was frequently present at levels equal to or exceeding the aerosol NH4+. Maximum level were 3800, 3100, 690 and 4540 neq m−3 for NH4+, NO32− and NH3(g), respectively. The fogwater collected at Riverside had very high concentrations, particularly of the major aerosol components. Maximum concentrations were 26,000 29,000 and 6200 μM for NH4+, NO3 and SO42−, respectively. pH values in fogwater ranged from 2.3 to 5.7. Formate and acetate concentrations as high as 1500 and 580 μM, respectively, were measured. The maximum CH2O concentration was 380 μM. Glyoxal and methylglyoxal were found in all the samples; their maximum concentrations were 280 and 120 μM, respectively. Comparison of fogwater and aerosol concentrations indicates that scavenging of precursor aerosol by fog droplets under the conditions at Riverside is less than 100% efficient.The chemistry at Riverside is controlled by the balance between HNO3 production from NOx emitted throughout the Los Angeles basin and NH3 emitted from dairy cattle feedlots just west of Riverside. The balance is controlled by local mixing. Acid fogs result at Riverside when drainage flows from the surrounding mountains isolate the site from the NH3 source. Continued formation of HNO3(g) in this air mass eventually depletes the residual NH3(g). A simple box model that includes deposition, fog scavenging, and dilution is used to assess the effect of curtailing the dairy cattle feedlot operations. The calculations suggest that the resulting reduction of NH3 levels would decrease the total NO3 in the atmosphere, but nearly all remaining NO3 would exist as HNO3. Fogwater in the basin would be uniformly acidic.  相似文献   

6.
Measurements of gaseous HNO3, HCl and NH3 and particulate NO3, SO42−, Cl and NH4+ have been made at a small network of sites in eastern England using sampling intervals from 3 h to 7 days. Both HCl and HNO3 are spatially rather uniform, with some variation apparently due to spatial variations in NH3, which stoichiometrically exeeded the sum of both gaseous acids. Mean concentrations of NH3, HCl and HNO3 between February 1987 and January 1988 were 1.90, 0.67 and 1.01 μg m−3, respectively. Pollution roses revealed low NH3 concentrations, and high associated HCl and HNO3 with winds from the North Sea. HCl, but not HNO3 showed an appreciable elevation in concentration on the sector NW from our site, which we speculate may be due to the large capacity of coal-fired power stations in this upwind sector. Three-hourly data have been examined for diurnal effects and its is concluded that nocturnal formation of NO3 is occurring.  相似文献   

7.
邯郸市PM_(2.5)中水溶性无机离子污染特征及来源解析   总被引:4,自引:1,他引:3  
本研究通过对邯郸市环境空气中PM2.5样本进行采集和成分检测,分析了该地区PM2.5中水溶性无机离子的污染特征,并结合气象要素(风速、温度)、气态污染物(O3、NO2、SO2、CO)、SOR(硫氧化率)、NOR(氮氧化率)对其主要来源进行了解析.研究结果表明:总水溶性无机离子(TWSII)浓度季节变化特征明显,秋、冬季高于春、夏季.SO2-4、NO-3、NH+4是PM2.5中主要的水溶性无机离子,在TWSII中所占的比例为夏(93.2%)冬(85.6%)秋(85.5%)春(84.0%).春、夏、秋三季PM2.5呈酸性,冬季显碱性.此外还分析得到,SO2-4在四季中均以(NH4)2SO4的形式存在.NO-3在冬季以NH4NO3的形式存在,其余季节中以NH4NO3、HNO3等共存.绝大部分Cl-在冬季以NH4Cl的形式存在,其它季节中以NH4Cl、KCl等的形式存在.均相反应是SO2-4的主要生成途径,夏、冬季也伴随有非均相反应.NO-3的生成以均相反应为主(春、夏、秋),在冬季均相反应与非均相反应同时存在.应用因子分析法解析出4个主因子,其中,工业、燃煤、交通、生物质燃烧等综合源是PM2.5中水溶性无机离子的主要来源.  相似文献   

8.
Chemical composition of precipitation in Albany, NY from July 1986 to December 1988 has been studied. Mean volume-weighted concentrations (μeqℓ−1) were: acidity, 104.0; alkalinity, −63.7; SO42−, 52.8; NO3, 29.8; Cl, 5.6; F, 0.50; NH4+, 19.3; Ca2+, 6.5; Mg2+, 2.8; Na+, 3.5; and K+, 1.4. Mean pH was 4.2 . Seasonal patterns were pronounced for most species. Concentrations of H+, SO42−, NO3, NH4+ and Ca2+ peaked in the summer and spring. Deposition was related to rainfall amount by a power law relationship in which the exponent of the equation was ∮.6. Wet SO42− deposition was 2.35 keq ha−1 over a 30-month period. The SO42− and NO3 deposition rates observed at Albany indicate that transport from midwestern sources have a major influence at this site. On the average, free H+ ion concentrations determined from pH measurements accounted for 51% of the measured total acidity. There were unknown species, most likely organic acids, that could contribute to the acidity. Correlation and regression analyses indicated that major anions, SO42− and NO3, were closely associated with H+ and NH4+ ions. Factor analysis revealed four common factors which are related to fossil-fuel combustion, sea spray, cement factory and biomass burning.  相似文献   

9.
The precipitation chemistry of Greater Manchester, a Metropolitan County in the northwest of England, has been examined for small scale spatial variability using a network of 18 bulk precipitation collectors. Significant spatial variability was found for concentrations of non-marine SO42−, NO3, NH4+, Ca2+ and H+ ions. The statistical associations between the data were investigated using correlation, partial correlation and principal components analyses. It was found that zero-order correlation coefficients were inadequate for the interpretation of the data and that the computation of first, and higher order partial correlation coefficients was necessary in order to explain the interrelationships between the data and their spatial variability. The statistical associations between the data suggest relationships between Ca2+ and non-marine SO42−, and NO3+ in precipitation which are discussed in terms of their possible precursor species. Potential source effects were examined in conjunction with atmospheric removal processes. The dry deposition of SO4 particles, rather than the dry deposition of SO2, may explain the spatial variability of non-marine SO42−. The erosion of CaSO4 formed from the reaction of SO2 with CaCO3 on urban surfaces with subsequent resuspension is thought to be the basis of the relationship between Ca2+ and non-marine SO42− concentrations in precipitation. The wet and dry deposition of CaCO3 particles from local sources may be partially responsible for the spatial variability of H+, and dry deposition and scavenging of NH3, in conjunction with the predominant wind direction may explain the spatial variability of NO3 and NH4+ ions. Ammonia is thought to originate from sources both outside the study area and within it.  相似文献   

10.
Atmospheric dry deposition to branches of Pinus contorta and P. albicaulis was measured during summer 1987 in a sub-alpine zone at Eastern Brook Lake Watershed (EBLW), eastern Sierra Nevada, California. Results are presented as deposition fluxes of NO3, SO42−, PO43−, Cl, F, NH4+, Ca2+, Mg2+, Na+, K+, Zn2+, Fe3+, Mn2+, Pb2+ and H+, and compared with other locations in California and elsewhere. Deposition fluxes of anions and cations to the pine branches were low, several times lower than the values determined near the Emerald Lake Watershed (ELW), another sub-alpine location in the western Sierra Nevada. The sums of deposition fluxes of the measured cations and anions to pine surfaces were similar, in contrast to the ELW location where the sums of cation fluxes were much higher than the sums of anion fluxes. A strong positive correlation between depositions of NO3 and NH4+, as well as SO42− and Ca2+, suggested that large portions of these ions might have originated from particulate NH4NO3 and CaSO4 deposited on pine surfaces. An estimated total N dry deposition (surface deposition of NO3 and NH4+ and internal uptake of NO2 and HNO3) to the forested area of the EBLW was 29.54 eq ha−1 yr (about 414 g H ha−1 yr−1).  相似文献   

11.
Measurements of wet deposited NH4+, SO42−, NO3 and Cl, as well as airborne concentrations of these species and gaseous HNO3, HCl and NH3, have been made at a site in eastern England. Scavenging ratios based solely upon aerosol-associated species and upon aerosol plus gaseous airborne species are presented and compared with literature values. It appears that HCl and HNO3 have only a rather minor influence upon wet deposition at our site. Gaseous NH3 influences ground-level air chemistry appreciably, but scavenging ratios for NH4+ are low, even when based upon aerosol NH4+ concentrations alone, presumably due to altitudinal gradients in this species. The problems inherent in interpretation of scavenging ratios are discussed. Deposition of nitrogen in various chemical forms is estimated from rainwater and air composition. If a transport-limited deposition velocity is assumed for ammonia gas, dry deposition of this species accounts for around 40% of total nitrogen deposition to the ground.  相似文献   

12.
Rainwater samples in S. Paulo city were collected on an event basis from October 1983 to October 1985 covering two dry and two rainy periods. Bulk samples only were obtained. At the same site and period, fine, coarse and inhalable particles were also collected. Na+, Ca2+, K+, Mg2+, NO3, SO42− and NH4+ contents were determined in rainwater samples, while Na, Ca, K, Cl and S concentrations were measured in aerosol samples. Rainwater is slightly acid (mean pH = 5.0), and contains high concentrations of Ca2+, NO3, SO42− and NH4+. Dry and wet fluxes and washout ratios were determined for some elements. Results obtained suggest that the atmospheric composition in this city is strongly influenced by anthropogenic sources.  相似文献   

13.
Wet precipitation was collected in Thessaloniki, Greece, during the period March 1989–December 1990 by using an automatic wet-only precipitation sampler.Rainwater samples were analysed for major cations (H+, NH4+, Na+, K+, Ca2+, Mg2+) and anions (Cl, NO3, SO42−), in addition to acidity and conductivity measurements. The majority of rain had a neutral or alkaline character as a result of neutralization, primarily caused by calcareous soil dust and secondarily by atmospheric ammonia. In all rain, SO42− concentration exceeded NO3 concentration. The contribution of maritime sources to the total SO42− concentration was very low (<2%).The chemical composition of precipitation was analysed in conjunction with meteorological variables (season of the year, precipitation type, airflow patterns) to evaluate temporal variations and chemical source influence. Rain caused by weak, localized flows showed the highest acidity and the minimum influence of neutralization processes.  相似文献   

14.
An iterative least-squares method with a receptor model was applied to the analytical data of the precipitation samples collected at 23 points in the suburban area of Tokyo, and the number and composition of the source materials were determined. Thirty-nine monthly bulk precipitation samples were collected in the spring and summer of 1987 from the hilly and mountainous area of Tokyo and analyzed for Na+, K+, NH4+, Mg2+, Ca2+, F, Cl, Br, NO3 and SO42− by atomic absorption spectrometry and ion chromatography. The pH of the samples was also measured. A multivariate ion balance approach (Tsurumi, 1982, Anal. Chim. Acta138, 177–182) showed that the solutes in the precipitation were derived from just three major sources; sea salt, acid substance (a mixture of 53% HNO3, 39% H2SO4 and 8% HCl in equivalent) and CaSO4. The contributions of each source to the precipitation were calculated for every sampling site. Variations of the contributions with the distance from the coast were also discussed.  相似文献   

15.
海峡西岸经济区大气污染物排放清单的初步估算   总被引:6,自引:1,他引:5  
以2009年为基准年,结合污染源普查数据、统计年鉴及工业活动、居民生活等多个方面对海峡西岸经济区包括SO2、NOx、PM2.5、VOCs和NH3在内的大气污染物的排放量进行了估算,建立了海西区大气污染物排放清单.结果发现,上述5类污染物基准年的排放量分别为40.67×104、55.84×104、50.57×104、152.26×104和26.18×104t.其中,SO2、NOx及PM2.5的排放主要来自电厂,占排放总量的比例分别为25.58%、34.89%和38.75%;VOCs和NH3的主要排放源分别来自植被排放和养殖业,其贡献量分别为49.12%和47.07%.采用GIS对排放清单进行网格化处理,得出SO2、NOx及PM2.5的高排放强度区域与固定源的空间分布较为一致.此外,结合国家和地方"十二五"发展规划,采用情景分析方法估算了2015年海西区大气污染物的排放清单.与基准年相比,SO2、NOx和NH3的排放量呈下降趋势,PM2.5和VOCs的排放量呈大幅度增加.基准年排放清单的不确定性分析显示,VOCs排放估算的不确定度最大,为225%.  相似文献   

16.
The chemical composition of winter and spring cloud water sampled at 1620 masl elevation on Mt Rigi in central Switzerland was dominated by NO3, SO42−, NH4+ and H+. A wide range of concentration levels was observed, with maxima of 3700, 1800 and 4600 micronormal for NO3, SO42− and NH4+, respectively. Concentrations at a lower elevation (1030 masl) site on the mountain were higher due to lower cloud liquid water contents and higher pollutant levels at that site. The lowest pH observed was 2.95; large concentrations of NH3 in the region prevented pH values from falling even lower. A comparison of simultaneously sampled cloud water and precipitation revealed much higher concentrations for most species in the cloud water, except in one case of extreme precipitation riming when the concentrations in the two phases converged. An exception to the pattern was H+; at times the precipitation was more acidic than the cloud water. The chemical composition of the cloud drops varied with drop size. Drops smaller than 10 μm diameter were enriched in NO3, SO42− and NH4+ relative to larger drops. Since the larger drops are the ones most effeciently captured by snow crystals, knowledge of their composition is essential to understanding the chemical implications of accretional growth of precipitation.  相似文献   

17.
The use of filter packs and a cascade impactor during a series of research cruises in the southern area of the North Sea has yielded detailed spatial distribution patterns of aerosol concentrations, Cl, NO3, SO42−1 and NH4+ and gaseous concentrations, HCl, HNO3 and NH3. The overall distribution of the atmospheric concentrations closely parallels published modelled results for metallic species. The chemical transformations of these aerosols and gases are investigated together with their interactions with the seasalt aerosol. Aerosol chloride loss is greatest in the more polluted areas, whilst concentrations products of NH3 with HNO3 and HCl appear insufficient to sustain the existence of NH4NO3 and NH4Cl. Nitrate is associated predominantly with larger particles and appears to be present substantially as a surface coating on marine aerosol. The total dry deposition input for nitrogen species is calculated for the southern sector with extrapolation to the whole of the North Sea, using particle size weighted deposition velocities of 0.63 and 0.21 cm s−1 for NO3−1 and NH4+, respectively, and literature-derived values for the gaseous constituents. Finally the use of air-mass back trajectories illustrates the role of source regions in influencing the chemical composition of the North Sea atmosphere.  相似文献   

18.
Simultaneous aerosol and snow sampling was performed during a field campaign at the Alpine site Weissfluhjoch Davos, Switzerland (2540 m a.s.1.) from 1 January through 30 March 1988. In addition, a snow pit was sampled on 30 March 1988. Very good agreement between the new snow and pit snow samples was found for the measured major ions as well as for the stable isotopes δ18O and δD. Thus, snow pit samples obtained at this site during the winter months yield representative deposition patterns with a conserved stratigraphy. Generally, concentrations in snow were very low, with 3.5, 8.5, 5.2 and 2.4 μeq ℓ−1 for Cl, NO3, SO42−, respectively. The 36Cl and 10Be concentrations as well as the 10Be/36Cl ratios were comparable to the ones measured at Arctic sites. With the exception of NO3, no linear relation was obtained between atmospheric and snow concentrations, showing that the concept of scavenging ratios must be used with caution when looking at single snowfall events. The following precipitation-weighted mean scavenging ratios were found: 300 for NH4+, 350 for SO42−, 940 for total NO3(NO3+HNO3), 175 for 210Pb, and 750 for 10Be.  相似文献   

19.
The chemical composition of cloudwater in the Sierra Nevada is dominated by NO3, SO42−, and NH4+. Cloudwater pH is determined largely by the balance between the concentrations of these three species, although inputs of formic and acetic acid also are believed to be important, particularly when anthropogenic inputs are small. Cloudwater samples collected in Sequoia National Park (SNP) exhibited pH values ranging from 3.9 to 6.5; Yosemite National Park (YNP) cloudwater samples had pH values ranging from 3.8 to 5.2. Samples collected at YNP were more acidic than those collected at SNP. The difference in pH between the two regions appears to be due to relatively small differences in inputs of NO3, SO42−, and NH4+. In the absence of inputs of NH3, cloudwater pH values in the Sierra may fall below 3.Over 250 h of cloud interception were observed during a 12 month period at a cloud monitoring site at 1856 m elevaton in SNP. Estimates of cloudwater deposition of NO3, SO42−, and NH4+ indicate that cloud interception contributes significantly to regional acid deposition for closed forest canopies. Cloud interception may be the dominant deposition mechanism for isolated conifers and ridgetop canopies, where wind speeds are higher and cloudy air parcels can impact directly on foliar surfaces.  相似文献   

20.
广州干湿季典型灰霾过程水溶性离子成分对比分析   总被引:7,自引:4,他引:3  
利用广州气象台2011年地面逐时能见度和相对湿度数据,以及广州番禺南村大气成分站2011年逐时Marga数据、PM数据,对比分析了一次湿季(4—9月)灰霾过程和干季(10月—次年3月)灰霾过程的污染特征.研究表明,相对干季灰霾过程,湿季灰霾过程颗粒物浓度较低,且细粒子所占比例较高;由于湿季较干季光化学反应较为活跃及可能受气象因素的不同影响,导致干湿季灰霾过程颗粒物浓度的总体变化趋势相反;湿季灰霾过程二次无机离子(SO_4~(2-)、NH_4~+和NO_3~-)占PM_(2.5)质量百分比的76%,是PM_(2.5)的主要成分;干季灰霾过程二次无机离子(SO_4~(2-)、NH_4~+和NO_3~-)仅占PM_(2.5)质量百分比的34%;湿季硫氧化率(Sulfur Oxidation Ratio,SOR)、氮氧化率(Nitrogen Oxidation Ratio,NOR)值大于干季,说明二次离子对湿季灰霾的贡献比干季要大;湿季灰霾过程中气溶胶酸性比干季弱.根据相关性分析结果可知,湿季灰霾过程中,NH_4~+主要与SO_4~(2-)结合,Na+主要与Cl-及NO_3~-结合,K+主要与Cl-和NO_3~-结合,极少部分与SO_4~(2-)结合;而在干季灰霾过程中,NH_4~+除了与SO_4~(2-)结合之外,还以NH_4NO_3和NH_4Cl的形式存在,K~+主要与Cl~-和SO_4~(2-)结合,Na+主要与Cl~-及SO_4~(2-)结合.  相似文献   

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