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1.
An in-cloud scavenging case study of the major ions (NH4 +, SO4 2- and NO3 -) determining the cloudwater composition at a mountain site (1620 m.a.s.l.) is presented. A comparison between in-cloud measurements of the cloudwater composition, liquid water content, gas concentrations and aerosol concentrations and pre-cloud gas and aerosol concentrations yields the following results. Cloudwater concentrations resulted from scavenging of about half of the available NH3, aerosol NH4 +, aerosol NO3 -, and aerosol SO4 2-. Approximately a third of the SO2 was scavenged by the cloudwater and oxidized to SO4 2-. Cloud acidity during the first two hours of cloud interception (pH 3.24) was determined mostly by the scavenged gases (NH3, SO2, and HNO3); aerosol contributions to the acidity were found to be small. Observations of gas and aerosol concentrations at three elevations prior to several winter precipitation events indicated that NH3 concentrations are typically half (12–80 %) of the total (gas and aerosol) N (-III) concentrations. HNO3 typically is present at much lower concentrations (1–55 %) than aerosol NO3 -. Concentrations of SO2 are a substantial component of total sulfur, with concentrations averaging 60 % (14–76 %) of the total S (IV and VI).  相似文献   

2.
In this study bulk airborne aerosol composition measured by the PILS-IC (integration time of 3 min 24 s) during TRACE-P P3B Flight 10 are used to investigate the ionic chemical composition and mixing state of biomass burning particles. A biomass burning plume, roughly 3–4 days old, moderately influenced by urban pollution aerosols recorded in the Philippine Sea is investigated. Focusing on the fine particle NO3−, SO42−, K+, NH4+, and water-soluble organics, the observed correlations and nearly 1-to-1 molar ratios between K+ and NO3− and between NH4+ and (SO42−+ inferred Organics) suggest the presence of fine-mode KNO3, (NH4)2SO4, and NH4(Organics) aerosols. Under the assumption that these ion pairs existed, and because KNO3 is thermodynamically less favored than K2SO4 in a mixture of NO3−, SO42−, K+, NH4+, and Organic anions, the measurements suggest that aerosols could be composed of biomass burning particles (KNO3) mixed to a large degree externally with the (NH4)2SO4 aerosols. A “closed-mode” thermodynamic aerosol simulation predicts that a degree of external mixing (by SO42− mass) of 60 to 100% is necessary to achieve the observed ionic associations in terms of the existence of KNO3. However, the degree of external mixing is most likely larger than 90%, based on both the presence of KNO3 and the amounts of NH4NO3. Calculations are also shown that the aerosol mixing state significantly impacts particle growth by water condensation/evaporation. In the case of P3B Flight #10, the internal mixture is generally more hygroscopic than the external mixture. This method for estimating particle mixing state from bulk aerosol data is less definitive than single particle analysis, but because the data are quantitative, it may provide a complementary method to single particle chemical analysis.  相似文献   

3.
This study systematically analyzed the concentrations of cations and anions and determined the pH in the rainwater at Guiyang from Oct. 2008 to Sep. 2009. The pH in the rainwater varied between 3.35 and 9.99 with a volume-weighted mean value of 4.23. The volume-weighted mean concentrations of anions followed the order SO4 2->Cl->F->NO3 -, whereas the volume-weighted mean concentrations of cations followed the order Ca2+>NH4 +>Na+>Mg2+>K+. This finding indicates that SO4 2- was the main anion and that Ca2+ and NH4 + were the main cations. Significant correlations between each pair of ions (SO4 2-, NO3 -, NH4 +, Ca2+, and Mg2+) were observed, suggesting that CaSO4, Ca(NO3)2, MgSO4, Mg(NO3)2, NH4NO3, (NH4)2SO4, and/or NH4HSO4 exist in the atmosphere at Guiyang. The soil-derived species (such as Ca2+) played an important role in the neutralization of the acidity in rainwater. The SO4 2- and NO3 - in the rainwater were mainly from anthropogenic sources, and their contributions accounted for 98.1 % and 94.7 %, respectively. NH4 + was also most likely derived from anthropogenic sources, such as domestic and commercial sewage, and played an important role in the neutralization of the rainwater at Guiyang.  相似文献   

4.
Beijing is one of the largest and most densely populated cities in China. PM2.5 (fine particulates with aerodynamic diameters less than 2.5 μm) pollution has been a serious problem in Beijing in recent years. To study the temporal and spatial variations in the chemical components of PM2.5 and to discuss the formation mechanisms of secondary particles, SO2, NO2, PM2.5, and chemical components of PM2.5 were measured at four sites in Beijing, Dingling (DL), Chegongzhuang (CG), Fangshan (FS), and Yufa (YF), over four seasons from 2012 to 2013. Fifteen chemical components, including organic carbon (OC), elemental carbon (EC), K+, NH4 +, NO3 ?, SO4 2?, Cl?, Al, Ca, Fe, Mg, Na, Pb, Si, and Zn, were selected for analysis. Overall, OC, SO4 2?, NO3 ?, and NH4 + were dominant among 15 components, the annual average concentrations of which were 22.62 ± 21.86, 19.39 ± 21.06, 18.89 ± 19.82, and 13.20 ± 12.80 μg·m?3, respectively. Compared with previous studies, the concentrations of NH4 + were significantly higher in this study. In winter, the average concentrations of OC and EC were, respectively, 3 and 2.5 times higher than in summer, a result of coal combustion during winter. The average OC/EC ratios over the four sites were 4.9, 7.0, 8.1, and 8.4 in spring, summer, autumn, and winter, respectively. The annual average [NO3 ?]/[SO4 2?] ratios in DL, CG, FS, and YF were 1.01, 1.25, 1.08, and 1.12, respectively, which were significantly higher than previous studies in Beijing, indicating that the contribution ratio of mobile source increased in recent years in Beijing. Analysis of correlations between temperature and relative humidity and between SOR ([SO4 2?]/([SO4 2?] + [SO2])) and NOR ([NO3 ?]/([NO3 ?] + [NO2])) indicated that gas-phase oxidation reactions were the major formation mechanism of SO4 2? in spring and summer in urban Beijing, whereas slow gas-phase oxidation reactions and heterogeneous reactions both occurred in autumn and winter. NO3 ? was mainly formed through year-round heterogeneous reactions in urban Beijing.  相似文献   

5.

Size-segregated aerosol particles were collected using a high volume MOUDI sampler at a coastal urban site in Xiamen Bay, China, from March 2018 to June 2020 to examine the seasonal characteristics of aerosol and water-soluble inorganic ions (WSIIs) and the dry deposition of nitrogen species. During the study period, the annual average concentrations of PM1, PM2.5, PM10, and TSP were 14.8?±?5.6, 21.1?±?9.0, 35.4?±?14.2 μg m?3, and 45.2?±?21.3 μg m?3, respectively. The seasonal variations of aerosol concentrations were impacted by the monsoon with the lowest value in summer and the higher values in other seasons. For WSIIs, the annual average concentrations were 6.3?±?3.3, 2.1?±?1.2, 3.3?±?1.5, and 1.6?±?0.8 μg m?3 in PM1, PM1-2.5, PM2.5–10, and PM>10, respectively. In addition, pronounced seasonal variations of WSIIs in PM1 and PM1-2.5 were observed, with the highest concentration in spring-winter and the lowest in summer. The size distribution showed that SO42?, NH4+ and K+ were consistently present in the submicron particles while Ca2+, Mg2+, Na+ and Cl? mainly accumulated in the size range of 2.5–10 μm, reflecting their different dominant sources. In spring, fall and winter, a bimodal distribution of NO3? was observed with one peak at 2.5–10 μm and another peak at 0.44–1 μm. In summer, however, the fine mode peak disappeared, likely due to the unfavorable conditions for the formation of NH4NO3. For NH4+ and SO42?, their dominant peak at 0.25–0.44 μm in summer and fall shifted to 0.44–1 μm in spring and winter. Although the concentration of NO3–N was lower than NH4–N, the dry deposition flux of NO3–N (35.77?±?24.49 μmol N m?2 d?1) was much higher than that of NH4–N (10.95?±?11.89 μmol N m?2 d?1), mainly due to the larger deposition velocities of NO3–N. The contribution of sea-salt particles to the total particulate inorganic N deposition was estimated to be 23.9—52.8%. Dry deposition of particulate inorganic N accounted for 0.95% of other terrestrial N influxes. The annual total N deposition can create a new productivity of 3.55 mgC m?2 d?1, accounting for 1.3–4.7% of the primary productivity in Xiamen Bay. In light of these results, atmospheric N deposition could have a significant influence on biogeochemistry cycle of nutrients with respect to projected increase of anthropogenic emissions from mobile sources in coastal region.

  相似文献   

6.
Industrial pollution has a significant effect on aerosol properties in Changsha City, a typical city of central China. Therefore, year-round measurements of aerosol optical, radiative and chemical properties from 2012 to 2014 at an urban site in Changsha were analyzed. During the observation period, the energy structure was continuously optimized, which was characterized by the reduction of coal combustion. The aerosol properties have obvious seasonal variations. The seasonal average aerosol optical depth (AOD) at 500 nm ranged from 0.49 to 1.00, single scattering albedo (SSA) ranged from 0.93 to 0.97, and aerosol radiative forcing at the top of the atmosphere (TOA) ranged from ?24.0 to 3.8 W m?2. The chemical components also showed seasonal variations. Meanwhile, the scattering aerosol, such as organic carbon, SO42?, NO3?, and NH4+ showed a decrease, and elemental carbon increased. Compared with observation in winter 2012, AOD and TOA decreased by 0.14 and ?1.49 W m?2 in winter 2014. The scattering components, SO42?, NO3? and NH4+, decreased by 12.8 μg m?3 (56.8%), 9.2 μg m?3 (48.8%) and 6.4 μg m?3 (45.2%), respectively. The atmospheric visibility and pollution diffusion conditions improved. The extinction and radiative forcing of aerosol were significantly controlled by the scattering aerosol. The results indicate that Changsha is an industrial city with strong scattering aerosol. The energy structure optimization had a marked effect on controlling pollution, especially in winter (strong scattering aerosol).  相似文献   

7.
2018年1月,利用颗粒物采样器采集武汉市大气PM2.5样品并进行水溶性无机离子（F-、Cl-、NO3-、SO42-、Na+、NH4+、K+、Mg2+、Ca2+）的分析.结果表明,NO3-、SO42-、NH4+是PM2.5中最主要的3种水溶性无机离子,除Mg2+与Ca2+外,PM2.5与WSⅡs （水溶性无机离子）之间的相关性显著,且移动源贡献占主导地位.阴阳离子平衡表明武汉市冬季灰霾期PM2.5呈中性或弱酸性.通过混合单粒子拉格朗日综合轨迹模式模拟并采用分层聚类得出了4种主要的后向气流轨迹及相应的PM2.5和水溶性离子浓度,结果表明区域传输对此次灰霾期影响较大.  相似文献   

8.
Secondary aerosol formation was studied at Allahabad in the Indo-Gangetic region during a field campaign called Land Campaign-II in December 2004 (northern winter). Regional source locations of the ionic species in PM10 were identified by using Potential Source Contribution Function (PSCF analysis). On an average, the concentration of water soluble inorganic ions (sum of anions and cations) was 63.2 μgm−3. Amongst the water soluble ions, average NO3− concentration was the highest (25.0 μgm−3) followed by SO42− (15.8 μgm−3) and NH4+ (13.8 μgm−3) concentrations. These species, contributed 87% of the total mass of water soluble species, indicating that most of the water soluble PM10 was composed of NH4NO3 and (NH4)2SO4/NH4HSO4 or (NH4)3H(SO4)2 particles. Further, the concentrations of SO42−, NO3−, and NH4+ aerosols increased at high relative humidity levels up to the deliquescence point (∼63% RH) for salts of these species suggesting that high humidity levels favor the conversion and partitioning of gaseous SO2, NOx, and NH3 to their aerosol phase. Additionally, lowering of ambient temperature as the winter progressed also resulted in an increase of NO3− and NH4+ concentrations, probably due to the semi volatile nature of ammonium nitrate. PSCF analysis identified regions along the Indo-Gangetic Plain (IGP) including Northern and Central Uttar Pradesh, Punjab, Haryana, Northern Pakistan, and parts of Rajasthan as source regions of airborne nitrate. Similar source regions, along with Northeastern Madhya Pradesh were identified for sulfate.  相似文献   

9.
A comprehensive study on the chemical compositions of rainwater was carried out from Jan. to Dec. in 2008 in Chengdu, a city located on the acid rain control zone of southwest China. All samples were analyzed for pH and major ions (F–, Cl?, NO3?, SO42?, K+, Na+, Ca2+, Mg2+, and NH4+). The pH increased due to the result of neutralization caused by the base ions. It was observed that Ca2+ was the most abundant cation with a VWM value of 196.6 μeq/L (17.3–1568.7 μeq/L), accounting for 49.7% (9.4%–79.2%) of the total cations. SO42? was the most abundant anion with VWM value of 212.8 μeq/L (41.8–1227.6 μeq/L). SO42? and NO3? were dominant among the anions, accounting for 90.4%–99.1% of the total measured anions.The concentrations of NO3? were higher than the most polluted cities abroad, which indicated Chengdu has been a severe polluted city over the world. The high fuel consumption from urbanization and the rapid increase of vehicles resulted in the high emission of SO2 and NOx, which were the precursor of the high concentration of acidic ions NO3? and SO42?. It was the main reason of the severe acid rain in Chengdu.The high concentrations of alkaline ions (mainly Ca2+, NH4+) in Chengdu city atmosphere have played an important role to neutralize the acidity of rainwater and the pH value has increased by 0.7 units since 1989. It is worth noting that the emission of NOx from the automobile exhaust is increased and is becoming the important precursor of acid rain now.  相似文献   

10.
本文利用气体组分及大气气溶胶在线监测系统(MARGA ADI 2080)观测武汉市2018年1月9—26日大气气溶胶中的8种水溶性离子(NH+4、NO-3、SO2-4、Cl-、K+、Ca2+、Na+和Mg2+),结合气象要素数据,使用主成分分析(PCA)、正定矩阵因子分析法(PMF)、HYSPLIT后向轨迹模式、潜在源区贡献(PSCF)和浓度权重轨迹(CWT),对霾污染过程中水溶性离子进行了全面的来源解析,探究了霾不同阶段下来源差异和空间分布特征。结果表明:(1)本次霾污染中的8种水溶性离子和4种污染气体,PCA解析出的源和占比分别为二次源和燃煤源的混合源(41.28%)、工业排放和土壤扬尘混合源(27.73%)和机动车排放源(9.63%),PMF解析出的源和占比分别为燃煤与土壤扬尘混合源(18.57%)、机动车排放源(20.74%)、二次源(18.30%)、光化学污染源(22.24%)和燃煤源(20.15%)。(2)霾在不同阶段下水溶性离子和4种污染气体的来源存在差异,在清洁天和霾消散阶段,光化学的贡献最高,占比分别为31.42%和36.07%;在霾发生阶段燃煤与土壤扬尘源的贡献最高,其贡献为40.94%;在霾发展阶段,最大的控制源为二次源,贡献占比为37.51%。(3)此次武汉市霾污染中PM2.5浓度和NH+4、NO-3和SO2-4的潜在源区为皖豫鄂三省和赣湘鄂三省交界处。霾污染中PM2.5的主要影响范围是武汉市南部和北部省份,NO-3、NH+4和SO2-4的主要影响区域为武汉市东北方向的城市、湖南省和江西省。  相似文献   

11.
Daily rainwater samples collected at Lijiang in 2009 were analyzed for pH, electrical conductivity, major ion (SO4 2?, Cl?, NO3 ?, Na+, Ca2+, Mg2+, and NH4 +) concentrations, and δ18O. The rainwater was alkaline with the volume-weighted mean pH of 6.34 (range: 5.71 to 7.11). Ion concentrations and δ18O during the pre-monsoon period were higher than in the monsoon. Air mass trajectories indicated that water vapor from South Asia was polluted with biomass burning emissions during the pre-monsoon. Precipitation during the monsoon was mainly transported by flow from the Bay of Bengal, and it showed high sea salt ion concentrations. Some precipitation brought by southwest monsoon originated from Burma; it was characterized by low δ18O and low sea salt, indicating that the water vapor from the region was mainly recycled monsoon precipitation. Water vapor from South China contained large quantities of SO4 2?, NO3 ?, and NH4 +. Throughout the study, Ca2+ was the main neutralizing agent. Positive matrix factorization analysis indicated that crustal dust sources contributed the following percentages of the ions Ca2+ 85 %, Mg2+ 75 %, K+ 61 %, NO3 ? 32 % and SO4 2? 21 %. Anthropogenic sources accounted for 79 %, 68 %, and 76 % of the SO4 2?, NO3 ? and NH4 +, respectively; and approximately 93 %, 99 %, and 37 % of the Cl?, Na+, and K+ were from a sea salt source.  相似文献   

12.
Gaseous pollutants and PM2.5 aerosol particles were investigated during a tropical storm and an air pollution episode in southern Taiwan. Field sampling and chemical analysis of particulate matter and gaseous pollutants were conducted in Daliao and Tzouying in the Kaohsiung area, using a denuder-filter pack system during the period of 22 October to 3 November 2004. Sulfate, nitrate and ammonium were the major ionic species in the PM2.5, accounting for 46 and 39% of the PM2.5 for Daliao and Tzouying, respectively. Higher PM2.5, Cl?, NO3? and NH4+, HNO2 and NH3 concentrations were found at night in both stations, whereas higher HNO3 was found during the day. In general, higher PM2.5, HCl, NH3, SO2, Cl?, NO3?, SO42? and NH4+ concentrations were found in Daliao. The synoptic weather during the experiment was first influenced by Typhoon NOCK-TEN, which resulted in the pollutant concentrations decreasing by about two-thirds. After the tropical thunderstorm system passed, the ambient air quality returned to the previous condition in 12 to 24 h. When there was a strong subsidence accompanied by a high-pressure system, a more stable environment with lower wind speed and mixing height resulted in higher PM2.5, as well as HNO2, NH3, SO42?, Cl?, NO3?, NH4+ and K+ concentrations during the episode days. The rainfall is mainly a scavenger of air pollutants in this study, and the stable atmospheric system and the high emission loading are the major reasons for high air pollutant concentrations.  相似文献   

13.
Large number of rain water samples, at 7 rural locations in the semi-arid region of the DeccanPlateau were collected during 4 consecutive monsoon seasons (1979-1982).pH, conductivityand the major ionic components (C1~-, SO_4~= , NO_3~- , NH_4~+ , Na~+, K~+, Ca~(++), Mg~(++) of the abovesamples were determined. The pH of rain water was found to be highly alkaline and the valuesvaried from 6.4 to 7.8. Soil-oriented elements showed good correltioan (r~0.6) with pH valuesof rain water. The high concentration of soil-oriented elements, specially Ca~(++), is found to play animportant role in neutralizing the acidity of rain water and maintaining high alkaline pH. The studysuggested that the contribution of atmospheric aerosol of natural sources (sea and soil) to thechemical composition of rain water is more than that of anthropogenic origin.  相似文献   

14.
Spatial variation of long term annual precipitation volume weighted concentrations of major chemical constituents (SO4 ?2, NO3 ?, Cl?, NH4 +, Ca+2, Mg+2, Na+ and K+ ) at all the ten Global Atmospheric Watch (GAW) stations in India for the period from 1981 to 2012 is studied in this paper. Ionic abundance and balance is studied as well. The range of long term annual mean pH at ten stations was 5.25?±?0.82 to 6.91?±?0.76, lowest at Mohanbari and highest at Jodhpur. The long term annual mean pH for the period 1981–2012 showed decreasing trend at all the stations (significant at 5 % level). Decadal mean pH among ten stations for 1981–1990, 1991–2000 and 2001–2012 ranged between 7.31 to 5.76, 7.45 to 4.92 and 6.16 to 4.77 respectively and showed decreasing trend at all the stations during 1981–1990 to 2001–12. The percentage occurrence of acidic pH (<5.65) at ten stations ranged from 3 to 72 %, lowest at Jodhpur and highest at Mohanbari and it increased from 1981–1990 to 2001–2012 almost at all the stations. Temporal variation of annual mean values of nssSO4 ?2, NO3 ?, Ca+2 and pH for the study period were attempted. Variation of nss K (non sea salt Potassium) at all the stations was studied to assess the biomass burning contribution in different regions. Non-marine (terrestrial) contribution dominated for majority of ionic constituents at most of the stations. However marine contribution was found to be dominant for Mg at Port Blair and Minicoy. Also sea salt fraction of SO4 was higher than terrestrial at Minicoy. Sources of measured ionic constituents in rain water are assessed through correlation analysis. The concentrations of all the ionic species were lowest at Kodaikanal, a high altitude hill top station and the total ionic mass was 136.0 μeq/l. Jodhpur, an arid station not only had highest concentrations of Ca+2, SO4 ?2 and K+ but also had highest total ionic content (1051.8 μeq/l) among all the stations. At Srinagar, Jodhpur, Allahabad, Nagpur and Pune stations Ca+2 was the dominant cation while dominant anion was NO3 ? for Srinagar, Allahabad, and Nagpur and Cl? for Jodhpur and Pune; at Mohanbari NO3 ? and Ca+2; at Visakhapatnam, Port Blair and Minicoy Na+ and Cl? were abundant. Temporal variation had shown an increasing trend for nssSO4 ?2 and NO3 ? and obviously decreasing trend for pH at all the stations. However, Ca+2 showed a decreasing trend at all the stations except at Port Blair. With the exception of Pune and Jodhpur stations, nssK showed a decreasing trend at all the stations revealing decreasing influence of soil/biomass burning over Indian GAW stations. Negative correlation of pH with SO4 ?2 was found to be weak compared to NO3 –.  相似文献   

15.
庐山云雾水化学组分的某些特征   总被引：23，自引：5，他引：23  
在庐山电视台采集的云雾水与同时段、同一地点采集的雨水相比,除Cl~-外各种离子浓度前者明显高些,pH值也较高。云雾水和地面同时段雨水相比较,云雾水中NO~-_3,SO~-_4,NH~+_4,Ca~(++),F~-及Mg~(++)等离子浓度也较高,但云雾水和雨水二者比值较小,云雾水的pH值也较高。云雾水中离子浓度和上风向污染源关系密切,其主要通过气溶胶的输送从而影响云雾水成份。有雨情况下云雾水中的离子浓度随时间推移而逐渐减少。  相似文献   

16.
In the present paper, we have characterized the ambient ammonia over Delhi along with other trace gases (NH3, NO, NO2, SO2 and CO) and particulates (PM2.5 and PM10) measured during December 2011 to June 2012. The average mixing ratios of ambient NH3, NO, NO2, SO2 and CO were recorded as 21.2 ± 5.4, 19.5 ± 4.9, 17.4 ± 1.4, 1.7 ± 0.5 ppb and 1.6 ± 0.7 ppm, respectively, during winter, whereas the average mixing ratios of ambient NH3, NO, NO2, SO2 and CO were recorded as 20.8 ± 4.7, 21.7 ± 6.3, 16.8 ± 3.1, 2.2 ± 0.8 ppb and 1.8 ± 0.9 ppm, respectively, during summer. In the present case, non-significant seasonal and diurnal variations of NH3, NO, NO2, SO2 and CO were observed during both the seasons. The average monthly NH3/NH4 + ratios varied from 0.28 to 2.56 with an average value of 1.46 in winter. The higher NH3/NH4 + ratio (3.5) observed in summer indicates the abundance of NH3 in the atmosphere during summer. The higher fraction of particulate NH4 + observed in winter than summer attributes to the conversion of gaseous NH3 into NH4 +. The results emphasized that the traffic could be one of the significant sources of ambient NH3 at the urban site of Delhi as illustrated by positive correlations of NH3 with traffic-related pollutants (NO, NO2 and CO). Surface wind analysis and wind directions also support the roadside traffic and agricultural activities at the nearby area indicating possible major sources of ambient NH3 at the study site.  相似文献   

17.
An hourly quantification of inorganic water-soluble PM10 ions and corresponding trace gases was performed using the Monitor for AeRosols and Gases in ambient Air (MARGA) at the TROPOS research site in Melpitz, Germany. The data availability amounts to over 80% for the five-year measurement period from 2010 to 2014. Comparisons were performed for the evaluation of the MARGA, resulting in coefficients of determinations (slopes) of 0.91 (0.90) for the measurements against the SO2 gas monitor, 0.84 (0.88), 0.79 (1.39), 0.85 (1.20) for the ACSM NO3 ?, SO4 2? and NH4 + measurements, respectively, and 0.85 (0.65), 0.88 (0.68), 0.91 (0.83), 0.86 (0.82) for the filter measurements of Cl?, NO3 ?, SO4 2? and NH4 +, respectively. A HONO comparison with a batch denuder shows large scatter (R2 = 0.41). The MARGA HNO3 is underestimated compared to a batch and coated denuder with shorter inlets (slopes of 0.16 and 0.08, respectively). Less NH3 was observed in coated denuders for high ambient concentrations. Long-time measurements show clear daily and seasonal variabilities. Potential Source Contribution Function (PSCF) analysis indicates the emission area of particulate ions Cl?, NO3 ?, SO4 2?, NH4 +, K+ and gaseous SO2 to lie in eastern European countries, predominantly in wintertime. Coarse mode sea salt particles are transported from the North Sea to Melpitz. The particles at Melpitz are nearly neutralised with a mean molar ratio of 0.90 for the five-year study. A slight increase of the neutralization ratio over the last three years indicates a stronger decrease of the anthropogenically emitted NO3 ? and SO4 2? compared to NH4 +.  相似文献   

18.
The apportionment of atmospheric aerosols undertaken in Northern France during two sampling campaigns allowed to determine the influence of the atmospheric contribution of a heavy industrialized urban center on the particulate matter composition at a nearby rural site. The concentrations of major components and trace elements sampled by bulk filtration have been determined on June–July 2000 and January–February 2001, and the comparison of these two campaigns shows very well the importance of wind directions. The sources of 10 trace elements (Al, Ba, Cu, Fe, K, Mn, Pb, Sr, Ti and Zn) and 7 major components (Cl−, NO3−, SO42−, NH4+, Na, Mg and Ca) are better identified by studying their elemental contribution at each sampling site according to wind sectors. This kind of study shows that the concentrations recorded at the urban sampling site are always higher than those observed at the rural site as well during the summer campaign (about + 35%) as during the winter campaign (+ 90%), because of the predominance of the W–NW wind sector, corresponding to the influence of the urban and industrialized areas.  相似文献   

19.
The effects of below-cloud aerosol on the acidification process of rain   总被引：1，自引：0，他引：1  
Using a model of the acidification process of rain, we calculate and analyze the effects and contributions of a below-cloud aerosol in its different concentrations and acidities on the pH and ion components of rain (SO 4 2– , H+, NO 3 – , NH 4 + , etc.) under the conditions of different concentrations of pollution gases. The results show that the aerosol has an acidification or alkalization effect on the rain which changes the pHs of rain and aerosol. As acidifying pollution gas concentrations (SO2, HNO3) are low, the acid aerosol has important effects on the pH and H+ of rain, but as the gas concentrations are high, the acid aerosol has very little effect. The alkalizing aerosol makes the pH of rain increase by between 0.3 and 0.5 and neutralizes about 60% of H+ in the rain. As alkalizing pollution gas NH3 exists, the acid aerosol has important effects on the pH and H+ of rain. But the alkalizing aerosol has very little effect, especially as the NH3 concentration is high. The percentage contribution of the aerosol to SO 4 2– in rain is generally 7–15%, the contribution of the aerosol to NO 3 – is nearly the same as that of HNO3=1 ppb, and the contribution of the aerosol to NH 4 + is nearly the same as that of NH3, from 5 to 7 ppb, and is an important source of NH 4 + in rain. Finally, according to the actual conditions of typical regions in the south and north of China (Chongqing and Beijing), we analyze the effects of aerosol and pollution gases on the ion components of rain.  相似文献   

20.
Size-differentiated concentrations of SPM, F, Cl, NO3, SO4, Na, K, Ca, Mg and NH4 in atmospheric aerosols were measured in a suburban area of Agra city during December 1992 to March 1993. Except for NH4, Cl and Na, all components were found to have a bimodal distribution. The fine fraction was dominated by NH4, K, NO3 and SO4, while Na, Ca, Mg, F and Cl contributed to the coarse fraction. Fifty-eight percent of SO4 and 67% of NO3 were found in the fine mode and the coarse mode comprised 42 and 33% of SO4 and NO3, respectively. SO4 was found to have a peak above the submicron range at 1.1 µm which has been attributed to secondary sulphate formation by heterogeneous oxidation of SO2 on alkaline particles of Ca and Mg. The total aerosol was basic in nature and dominated by the soil-derived acid neutralising components (Ca, Mg and Na).  相似文献   

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