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1.
Gaseous pollutants and PM 2.5 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 PM 2.5, accounting for 46 and 39% of the PM 2.5 for Daliao and Tzouying, respectively. Higher PM 2.5, Cl ?, NO 3? and NH 4+, HNO 2 and NH 3 concentrations were found at night in both stations, whereas higher HNO 3 was found during the day. In general, higher PM 2.5, HCl, NH 3, SO 2, Cl ?, NO 3?, SO 42? and NH 4+ 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 PM 2.5, as well as HNO 2, NH 3, SO 42?, Cl ?, NO 3?, NH 4+ 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
2.
In recent years, China has implemented several measures to improve air quality. The Beijing-Tianjin-Hebei(BTH)region is one area that has suffered from the most serious air pollution in China and has undergone huge changes in air quality in the past few years. How to scientifically assess these change processes remain the key issue in further improving the air quality over this region in the future. To evaluate the changes in major air pollutant emissions over this region, this paper employs ens... 相似文献
3.
Continuous measurements of SO 2, NO x and O 3 along with sampling based measurements of CO, CH 4, NMHCs and CO 2 were carried out during May, 2010 at Ahmedabad. The diurnal variations of SO 2 in ambient air exhibited elevated values during the night and lower levels during the sunlit hours. The mean concentration of SO 2 during the study period was 0.95 ± 0.88 ppbv. However, the ambient SO 2 exceeded 17 ppbv in the night of 20 May, 2010. On the same day, tropospheric columnar SO 2 from OMI showed almost 350% increase corroborating the surface observations over an extended height regime. This was also the highest columnar value of SO 2 during the summer of 2010. Columnar loadings were also found to be high for formaldehyde, precipitable water vapor and aerosol optical depth on 20 May. Elevated concentrations were also recorded for other trace gases like NO 2 and O 3. Analysis of related data of trace gases indicated characteristics of fresh emissions with dominant contributions from mobile sources during the study period. However, SO 2/NO 2 ratio of 0.36 during the event period on 20th May connotes non-local influences. Analyses of meteorological parameters suggest combined impacts of transport and inversion causing higher levels of SO 2 and other pollutants during 20?C21 May. Episodes of such enhancements may perturb chemical and radiative balance of the atmosphere. 相似文献
4.
利用2008~2012年太原常规地面气象观测资料、高空探测资料和大气污染物观测资料,对主要天气形势、典型气象要素以及空气污染状况下灰霾天气特征及形成机制进行了综合分析。结果表明:1)太原地区灰霾出现频率存在明显的季节变化,冬半年灰霾出现天数占全年的65.7%;一天中08:00(北京时间,下同)至13:00发生灰霾的频率较高。2)霾日静风频率较高,主导风向为偏东南风;重度灰霾天气出现时相对湿度较高。3)霾日的大气稳定度主要表现为稳定类;霾日平均混合层高度比非霾日低约100 m;08:00逆温出现次数高于20:00,霾时平均逆温强度和厚度高于非霾时。4)高压类型天气形势对灰霾的产生有重要影响,低压天气形势下较少出现灰霾天气。5)可吸入颗粒物、SO2和NO2浓度在非霾日比霾日分别下降32.6%、48.6%、21.7%;随着灰霾等级的增加,SO2和可吸入颗粒物的浓度有显著的增加。6)灰霾天气下到达地面的太阳辐射强度明显减弱,日照时数明显减少。 相似文献
5.
A series of indoor air quality parameters were determined in two medieval churches, in Cyprus (temperature, relative humidity,
total and UV solar radiation, CO 2 indoors and O 3, NO, NO 2
*, HNO 3
*, HCl, HCOOH, CH 3COOH indoors and outdoors). These data were used as input in a validated indoor air quality model to predict indoor air pollutant
source strengths and species concentrations that resulted from dark or photochemical reactions. The NO and NO 2 emission rates due to the burning of incense or candles were estimated. Model results revealed that heterogeneous NO formation
takes place simultaneously with the heterogeneous HONO formation. Also, model application has shown that indoor NO x emissions resulted in decreased free radical concentrations, in contrast to the organic compound emissions, which increased
free radical concentrations. This effect of indoor emissions on indoor radicals can partly explain the indoor enhancement/depression
of indoor gaseous acid formation. 相似文献
6.
大气质量的周循环特征反映了人类周期性的活动规律对大气环境的影响.基于安徽省16个城市PM2.5、PM10、CO、NO2、SO2和O3这6种污染物的监测结果,对安徽省大气污染的周循环特征进行了评估.首先基于原始逐小时污染物浓度时间序列在日和周窗口时间宽度上的滑动平均序列,定义了周循环距平百分率序列的计算方法,排除了日循环... 相似文献
7.
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 PM 10 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 NO 3− concentration was the highest (25.0 μgm −3) followed by SO 42− (15.8 μgm −3) and NH 4+ (13.8 μgm −3) concentrations. These species, contributed 87% of the total mass of water soluble species, indicating that most of the water
soluble PM 10 was composed of NH 4NO 3 and (NH 4) 2SO 4/NH 4HSO 4 or (NH 4) 3H(SO 4) 2 particles. Further, the concentrations of SO 42−, NO 3−, 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 SO 2, NO x, and NH 3 to their aerosol phase. Additionally, lowering of ambient temperature as the winter progressed also resulted in an increase
of NO 3− and NH 4+ 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
8.
We investigated the acidity and concentrations of water-soluble ions in PM 2.5 aerosol samples collected from an urban site in Beijing and a rural site in Gucheng, Hebei Province from November 2016 to January 2017 to gain an insight into the formation of secondary inorganic species. The average SO 42–, NO 3–, and NH 4+ concentrations were 8.3, 12.5, and 14.1 μg m –3, respectively, at the urban site and 14.0, 14.2, and 24.2 μg m –3, respectively, at the rural site. The nitrogen and sulfur oxidation ratios in urban Beijing were correlated with relative humidity (with correlation coefficient r = 0.79 and 0.67, respectively) and the aerosol loadings. Based on a parameterization model, we found that the rate constant of the heterogeneous reactions for SO 2 on polluted days was about 10 times higher than that on clear days, suggesting that the heterogeneous reactions in the aerosol water played an essential role in haze events. The ISORROPIA II model was used to predict the aerosol pH, which had a mean (range) of 5.0 (4.9–5.2) and 5.3 (4.6–6.3) at the urban and rural site, respectively. Under the conditions with this predicted pH value, oxidation by dissolved NO 2 and the hydrolysis of N 2O 5 may be the major heterogeneous reactions forming SO 42– and NO 3– in haze. We also analyzed the sensitivity of the aerosol pH to changes in the concentrations of SO 42–, NO 3–, and NH 4+ under haze conditions. The aerosol pH was more sensitive to the SO 42– and NH 4+ concentrations with opposing trends, than to the NO 3– concentrations. The sensitivity of the pH was relatively weak overall, which was attributed to the buffering effect of NH 3 partitioning. 相似文献
9.
Pre and Post-Monsoon levels of ambient SO2, NO2, PM2.5 and the trace metals Fe, Cu, etc. were measured at industrial and residential regions of the Kochi urban area in South India for a period of two years. The mean PM2.5, SO2 and NO2 concentrations across all sites were 38.98?±?1.38 µg/m3, 2.78?±?0.85 µg/m3 and 11.90?±?4.68 µg/m3 respectively, which is lower than many other Indian cities. There was little difference in any on the measured species between the seasons. A few sites exceeded the NAAQS (define acronym and state standard) and most of the sites exceeded WHO (define acronym and state standard) standard for PM2.5. The average trace metal concentrations (ng/m3) were found to be Fe (32.58)?>?Zn (31.93)?>?Ni (10.13)?>?Cr (5.48)?>?Pb (5.37)?>?Cu (3.24). The maximum concentration of trace metals except Pb were reported in industrial areas. The enrichment factor, of metals relative to crustal material, indicated anthropogenic dominance over natural sources for the trace metal concentration in Kochi’s atmosphere. This work demonstrates the importance of air quality monitoring in this area. 相似文献
10.
An in-cloud scavenging case study of the major ions (NH 4
+, SO 4
2- and NO 3
-) 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 NH 3, aerosol NH 4
+, aerosol NO 3
-, and aerosol SO 4
2-. Approximately a third of the SO 2 was scavenged by the cloudwater and oxidized to SO 4
2-. Cloud acidity during the first two hours of cloud interception (pH 3.24) was determined mostly by the scavenged gases (NH 3, SO 2, and HNO 3); 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 NH 3 concentrations are typically half (12–80 %) of the total (gas and aerosol) N (-III) concentrations. HNO 3 typically is present at much lower concentrations (1–55 %) than aerosol NO 3
-. Concentrations of SO 2 are a substantial component of total sulfur, with concentrations averaging 60 % (14–76 %) of the total S (IV and VI). 相似文献
11.
The concentrations of H +, nitrate (NO 3
-), and sulfate (SO 4
2-) in rainwater and their temporal changes were analyzed on the basis of continuous observation from 1 July 1991 to 30 June 1992 at a suburb of Nagoya, Japan. The yearly average for pH was 4.4. In general, an increasing pH with increase in precipitation amount was observed for rain events. Relatively high pH rainwater was sometimes observed at the beginning of rainfall, even though high concentrations of NO 3
- and SO 4
2- were involved. The high pH values were considered to be caused by the neutralization process with particulate matter containing cations. The yearly averaged ratio of equivalent concentration of nitrate to sulfate (N/S) in rainwater was 0.58. In the early stage of rain, the N/S value was usually more than 1.0 due to the difference of scavenging process between NO 3
- and SO 4
2-. High values of N/S ranging from 5 to 10 were found under the atmospheric conditions of calm winds and low humidity, during which it is possible that atmospheric particles float for a long time in the air before a rain event. The adsorption of NO 3
- in the early stage of rainfall by particulate matter was suggested from the difference in scavenging processes of NO 3
- and SO 4
2-. A possible scavenging process, called limb cloud scavenging, is presented to explain the interaction of particles and nitrate ions at the early stage of rain. In limb cloud scavenging, the repeated migration of cloud particles or raindrops between the inside and outside of clouds increases the absorption of ions to a highly condensed level, thus increasing the N/S value of rainwater. The influence of global scale seasonal phenomena with large amounts of particulates, such as typhoons or Asian dust storms, was also studied. 相似文献
12.
随着城市化、工业化的快速发展,空气污染已经成为了公众最关注的问题之一。为了提高空气质量预报的准确度,以多尺度空气质量模型(Community Multi-Scale Air Quality,CMAQ)为工具,结合中尺度WRF(Weather Research and Forecast Model)气象预报数据、气象观测数据、污染物浓度观测数据,基于极端随机树方法建立了WRF-CMAQ-MOS(Weather Research and Forecast Model-Community Multi-Scale Air Quality-Model Output Statistics)统计修正模型。结果表明,结合WRF气象预报的CMAQ-MOS方法明显修正了由于模型非客观性产生的模式预报偏差,提高了预报效果。使用线性回归方法不能获得较好的优化效果,选取极端随机树方法和梯度提升回归树方法对模型进行改进和比较,发现极端随机树方法对结合WRF气象要素的CMAQ-MOS模型有较大的提升。针对徐州地区空气质量预报,进一步使用基于极端随机树方法的WRF-CMAQ-MOS模型对2016年1、2、3月的空气质量指数(AQI)及PM 2.5、PM 10、NO 2、SO 2、O 3、CO六种污染物优化试验进行验证,发现优化效果最为明显的两种污染物分别是NO 2及O 3,2016年1、2、3月整体相关系数NO 2由0.35升至0.63,O 3由0.39升至0.79,均方根误差NO 2由0.0346减至0.0243 mg/m3,O 3由0.0447减至0.0367 mg/m3。文中发展的WRF-CMAQ-MOS统计修正模型可以有效提升预报精度,在空气质量预报中具有很好的应用前景。 相似文献
13.
为了探明PM_(2.5)中水溶性无机离子的来源和气象因子对其浓度变化的影响,利用2012年2、5、8和11月苏州市PM_(2.5)中水溶性无机离子浓度和本站气象观测数据,分析了苏州市水溶性无机离子的时间变化特征,解析了当地PM_(2.5)中水溶性无机离子的主要来源,探讨了气象因素对离子组分的影响。结果表明:(1)苏州市PM_(2.5)中水溶性无机离子年均浓度大小依次为:SO_4~(2-)NO_3~-NH_4~+Na~+Cl~-K~+Ca~(2+)Mg~(2+)F~-;SO_4~(2-)、NH_4~+和NO_3~-为PM_(2.5)中最重要的3种水溶性无机离子物种,其总和占PM_(2.5)总质量浓度的50.9%。各离子的季节浓度特征均为冬季最高、夏季最低。(2)通过运用主成分分析法对苏州市PM_(2.5)中水溶性无机离子进行来源分类解析,发现第一类为二次污染源和生物质燃烧,其贡献率为32.84;第二类为道路扬尘及工业排放,其贡献率为19.99%;第三类为海盐污染,其贡献率为18.43%。(3)通过水溶性无机离子与气象条件的相关性分析发现,风向、风速和温度与水溶性无机离子浓度的相关性较显著,这三者是颗粒物浓度变化的主要影响因子。(4)利用HYSPLIT后向轨迹模式对外来污染物进入苏州市的轨迹进行聚类分析后发现:因受季风气候影响,苏州市外来污染物的输入路径存在明显的季节性变化特征,其中夏半年输送主径源自海上,冬半年主径源自内陆。 相似文献
14.
An hourly quantification of inorganic water-soluble PM 10 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 SO 2 gas monitor, 0.84 (0.88), 0.79 (1.39), 0.85 (1.20) for the ACSM NO 3 ?, SO 4 2? and NH 4 + 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 ?, NO 3 ?, SO 4 2? and NH 4 +, respectively. A HONO comparison with a batch denuder shows large scatter (R 2 = 0.41). The MARGA HNO 3 is underestimated compared to a batch and coated denuder with shorter inlets (slopes of 0.16 and 0.08, respectively). Less NH 3 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 ?, NO 3 ?, SO 4 2?, NH 4 +, K + and gaseous SO 2 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 NO 3 ? and SO 4 2? compared to NH 4 +. 相似文献
15.
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 SO 4 2->Cl ->F ->NO 3 -, whereas the volume-weighted mean concentrations of cations followed the order Ca 2+>NH 4 +>Na +>Mg 2+>K +. This finding indicates that SO 4 2- was the main anion and that Ca 2+ and NH 4 + were the main cations. Significant correlations between each pair of ions (SO 4 2-, NO 3 -, NH 4 +, Ca 2+, and Mg 2+) were observed, suggesting that CaSO 4, Ca(NO 3) 2, MgSO 4, Mg(NO 3) 2, NH 4NO 3, (NH 4) 2SO 4, and/or NH 4HSO 4 exist in the atmosphere at Guiyang. The soil-derived species (such as Ca 2+) played an important role in the neutralization of the acidity in rainwater. The SO 4 2- and NO 3 - in the rainwater were mainly from anthropogenic sources, and their contributions accounted for 98.1 % and 94.7 %, respectively. NH 4 + 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
16.
Aerosols consist of organic and inorganic species, and the composition and concentration of these species depends on their sources, chemical transformation and sinks. In this study an assessment of major inorganic ions determined in three aerosol particle size ranges collected for 1 year at Welgegund in South Africa was conducted. SO 42? and ammonium (NH 4+) dominated the PM 1 size fraction, while SO 42? and nitrate (NO 3) dominated the PM 1–2.5 and PM 2.5–10 size fractions. SO 42? had the highest contribution in the two smaller size fractions, while NO 3? had the highest contribution in the PM 2.5–10 size fraction. SO 42? and NO 3? levels were attributed to the impacts of aged air masses passing over major anthropogenic source regions. Comparison of inorganic ion concentrations to levels thereof within a source region influencing Welgegund, indicated higher levels of most species within the source region. However, the comparative ratio of SO 42? was significantly lower due to SO 42? being formed distant from SO 2 emissions and submicron SO 42? having longer atmospheric residencies. The PM at Welgegund was determined to be acidic, mainly due to high concentrations of SO 42?. PM 1 and PM 1–2.5 fractions revealed a seasonal pattern, with higher inorganic ion concentrations measured from May to September. Higher concentrations were attributed to decreased wet removal, more pronounced inversion layers trapping pollutants, and increases in household combustion and wild fires during winter. Back trajectory analysis also revealed higher concentrations of inorganic ionic species corresponding to air mass movements over anthropogenic source regions. 相似文献
17.
为探讨2003-2007年长春市污染新特征,了解大气污染物变化趋势,对市区内客车厂等6个环境空气质量国控点位监测数据进行了归纳计算,并采用API评价方法,得到了PM 10、SO 2和NO 2 3种污染物年均值变化曲线和各种污染类型天数,同时查明了大气污染物的来源。结果表明:2003-2007年间长春市大气污染主要呈现波动略上升的总体特征,据此从气象条件和城市能源消耗等角度分析成因,并提出加深节能减排工作等一系列大气污染防治对策与建议。 相似文献
18.
A new version of an atmospheric pressure chemical ionisation mass spectrometer has been developed for ground based in situ
atmospheric measurements of OH and total peroxy (HO 2 + organic peroxy) radicals. Based on the previously developed principle of chemical conversion of OH radicals to H 2SO 4 in reaction with SO 2 and detection of H 2SO 4 using an ion molecule reaction with NO 3─, the new instrument is equipped with a turbulent chemical conversion reactor allowing for measurements in moderately polluted
atmosphere at NO concentrations up to several ppb. Unlike other similar devices, where the primary NO 3─ ions are produced using radioactive ion sources, the new instrument is equipped with a specially developed corona discharge
ion source. According to laboratory measurements, the overall accuracy and detection limits are estimated to be, respectively,
25% and 2 × 10 5 molecule cm -3 for OH and 30% and 1 × 10 5 molecule cm -3 for HO 2 at 10 min integration times. The detection limit for measurements of OH radicals under polluted conditions is 5 × 10 5 molecules cm -3 at 10 min integration times. Examples of ambient air measurements during a field campaign near Paris in July 2007 are presented
demonstrating the capability of the new instrument, although with reduced performance due to the employment of non isotopic
SO 2. 相似文献
19.
Summary Daily sampling of atmospheric PM 10 particulate was carried out using a continuously weighing, Tapered Element Oscillating Microbalance (TEOM) equipped with a PM 10 size selective inlet. The TEOM collects PM 10 on a small filter interfaced with an inertial mass transducer, which allows near continuous weighing of the filter as the deposit accumulates. The sampler was sited at several urban and sub-urban places in Córdoba City, Argentina. With the complete data set of chemical and meteorological variables (CO, NO x, O 3, wind speed, wind direction, ambient temperature, total and UV radiation, pressure and relative humidity, etc.) a stepwise regression was performed to select which variables have a major influence on the amount of PM 10 measured. Results are presented from the June 1995–May 1996 field campaign. Data for PM 10 values largely exceeded the one day standard average value of 150 g m –3 during several days. The largest amount of particulate has been measured during the winter season. The primary aim of this work is to define the concentration characteristics of ambient PM 10 at each site where this pollutant has been measured and to examine the seasonal variation of PM 10.With 3 Figures 相似文献
20.
Spatial variation of long term annual precipitation volume weighted concentrations of major chemical constituents (SO 4 ?2, NO 3 ?, Cl ?, NH 4 +, 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 nssSO 4 ?2, NO 3 ?, 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 SO 4 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, SO 4 ?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 NO 3 ? for Srinagar, Allahabad, and Nagpur and Cl ? for Jodhpur and Pune; at Mohanbari NO 3 ? and Ca +2; at Visakhapatnam, Port Blair and Minicoy Na + and Cl ? were abundant. Temporal variation had shown an increasing trend for nssSO 4 ?2 and NO 3 ? 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 SO 4 ?2 was found to be weak compared to NO 3 –. 相似文献
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