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1.
Summary For a comparison of snow chemistry data from different glaciers or snow fields it is important to have informations about the spatial representativeness of the data from each of the individual sites. In order to assess the representativeness of concentration data of major ions (volume weighted means of the winter accumulation) from glacier fields we investigated the variability in the average concentration of major ions from parallel samples within one snow pit and from different pits within one glacier field. The variabilities in the average concentrations of NO 3 - , SO 4 2- and NH 4 + for three parallel profiles within one snow pit at Goldbergkees (Austria) were 1.2, 3.3 and 2.0% (coefficient of variation). Cl– and Na+ showed larger variations (6.6 and 56.6%) possibly originating from contaminations. The variability of average concentration data from different snow pits within one glacier field was studied at La Grave (France) and at Goldbergkees (Austria). At La Grave 3 pits and at Goldbergkees 4 pits at distance of several hundred meters were sampled. Variabilities for SO 4 2- and NO 3 - were quite similar for the two sites (17% for both ions at La Grave, 12% and 15% at Goldbergkees). Whereas variabilities for Na+, NH 4 + , Mg2+, Ca2+ and Cl– were quite low at La Grave ( 12% and 27% for Cl–), higher values were obtained at Goldbergkees for these ions (17–56%). Likely reasons for the higher variability observed at Goldbergkees are a) higher spatial variability of crustal aerosol species (Mg2+, Ca2+), b) problems with the detection limit of the analytical method (Ca2+), c) contaminations (Na+, Cl–).With 4 Figures  相似文献   

2.
Rainwater samples were collected in Irbid city using 24 hour sampling periods from December 1996 to April 1998. All samples were analyzed for major cations (Na+, K+, Ca2+ and Mg2+), major anions (Cl–, NO3 – and SO4 2–) and pH. High levels of Ca2+ and SO4 2– were observed. Together, Ca2+ and SO4 2– made up more than 52.4% of the total ion mass, while Ca2+ alone contributed over 39.0% of the total cation. The majority of the rain samples collected had pH values higher than 5.6. The average pH was 6.4±0.9. High values of pH are attributed to the neutralization by natural alkaline local dusts which contain large fractions of calcite. Correlation and mineralogical analyses indicated that Ca2+, K+ and fractions of Na+, SO4 2– and Mg2+ are of crustal origin. Results of the present study suggested that the atmospheric composition in the city is strongly influenced by natural sources rather than anthropogenic.  相似文献   

3.
Rainwater samples were collected for the monsoon period of 1988 and 1991–1996 at Dayalbagh (Agra), a suburban site situated in semiaridregion. The mean pH was 7.01 ±1.03 well above 5.6, which is the reference pH. Concentration of Ca2+ was observed to be highest followed by Mg2+, NH4 +,SO4 2–, Cl–,NO3 –, Na+, F– and K+. The ratios of SO4 2– + NO3 – andCa2+ + Mg2+ (TA/TC) have been considered as indicatorfor acidity. In the Agra region ratio of TA/TC is quite below 1.0 indicating alkaline nature of rainwater. The lowest value of 0.24 was observed in 1991 likely due to the lowest rain depth of the decade. The highest value of 0.54 was observed in 1996, a year with a large rain depth and increase in line (vehicular traffic) and area sources (population growth). Good correlation between Ca2+ and NO3 –,Ca2+ and SO4 2– andSO4 2– and NO3 –,indicates that wind carried dust and soil play a significant role in neutralization of precipitation acidity.  相似文献   

4.
The results presented are the first complete analysis of inorganic soluble ions in a tropical savannah region. Atmospheric particles were collected in six rural Venezuelan savannah sites. Concentrations and size distribution of NO3 –, SO4 2-, CI–, PO4 3-, NH4 +, Na+, K+, Ca2+ and Mg2+ were determined in samples collected with Hi Vol samplers equipped with five-stage cascade impactors. Concentrations were higher in the dry season, with a maximum during the burning periods. Using Na+ as a reference, the results show a deficit of Cl– and, with the exception of Mg2+, an enrichment of all other ions with respect to marine aerosols. Significant variations were observed in particle-size distribution between different periods. Various pairs of ions present similar size distributions: SO4 2- and NH4 +; Cl– and Na+; PO4 3- and K+; Ca2+, Mg2+ and NO3 –; indicating that the ions were produced by the same source and/or were involved in similar atmospheric processes. Possible primary sources, the gas-to-particle atmospheric process, environmental implication of long-range transport of nutrients during dry seasons, etc., are discussed.  相似文献   

5.
In this study, variations of the chemical composition of precipitation in Nanjing, China, over a 12-year period (1992–2003) are presented. The average annual concentration of pH value was 5.15, ranging from 4.93 to 5.36, and there was no significant trend in the acidity of precipitation. SO42−, Cl− and NO3− were the main anions, while Ca2+, NH4+ and Mg2+ were the main cations. The concentrations of these main ions were very high compared to those reported in many other areas around the world. Most of the ions came from anthropogenic and crustal sources. High correlations were found among dust-derived cations Ca2+, Mg2+and K+, between Cl− and SO42−, between Cl− and NH4+ and between acidic anions and dust-derived cations, such as SO42− and Ca2+, SO42− and K+, Cl− and Ca2+, Cl− and K+, F− and Mg2+ and F− and K+. A significant decreasing trend was observed in concentration of SO42− because of the abatement strategies for SO2 emissions and energy policy change, while a significant increasing trend was found in the contribution of NO3− to acidification due to the rapidly growing number of motor vehicles. A significant decreasing trend was found in dust-derived cation Ca2+ due to more stringent controls of industrial dust emissions and rapid urbanization reducing the amount of open land, while the contribution of NH4+ to neutralization increased relatively.  相似文献   

6.
A comprehensive study on the chemical compositions of wet precipitation was carried out from January 2004 to December 2004 in Jinhua, southeastern China's Zhejiang Province. All samples were analyzed for pH, electrical conductivity and major ions (F−, Cl−, NO3−, SO42−, K+, Na+, Ca2+, Mg2+ and NH4+). The rainwater was typically acidic with a volume-weighted mean pH of 4.54, which ranged from 3.64 to 6.76. SO42− and NO3− were the main anions, while NH4+ and Ca2+ were the main cations. The concentrations of these major ions were generally higher compared to those reported in other parts of the world, but much lower than those in northern China.Wet deposition fluxes of major ions showed pronounced seasonal variations with maximum in spring and minimum in autumn. Significant correlations were found in soil-derived species among Ca2+, Mg2+ and K+ and sea-salt species between Na+ and Cl−. Other relatively good correlations were also observed between Ca2+ and SO42-, Mg2+ and SO42-, Mg2+ and NO3−, Mg2+ and Cl−. Principal component analysis was also performed on individual precipitation to find possible sources of the major ionic species. Varimax rotated four components accounting for 85.9% of the total variance, and were interpreted as acid and alkaline pollutants, sea spray and mixed source, soil and acid/neutralization. Calculation of enrichment factors for rainwater components relative to soil and seawater indicated that Ca2+ and K+ mainly originated from the terrestrial source, and SO42- and NO3− were mostly attributed for the anthropogenic activities in the study area. In general, the results suggested that precipitation chemistry is strongly influenced by anthropogenic sources rather than natural and marine sources. The pollutants in rainwater were mainly derived from long distance transport, local industry and traffic sources.  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.
The pH variation and chemical characteristics of rainwater were investigated from January 2006 to December 2006 at an urban site of Guangzhou, South China. The rainwater was typically acidic with a volume-weighted mean pH value of 4.49, which ranged from 3.52 to 6.28. The volume-weighted mean equivalent concentration of components followed the order: SO42− > Ca2+ > Cl− > NH4+ > Na+ > NO3− > K+ > Mg2+ > F−, indicating that SO42−, Cl− and NO3− were the main anions, while Ca2+ and NH4+, were the main cations. Ca2+ and NH4+ were major neutralization constituents of the precipitation. Furthermore, correlation analysis and principal component analysis method were performed to identify possible common sources of major ions. Sources of the major ions were assessed based on enrichment factor method.  相似文献   

9.
In November 2004–January 2005, a micro orifice uniform deposit impactor (MOUDI) and a Nanometer (nanometer)-MOUDI were used in the center of Taiwan to measure particle size (18 nm particle size 18 μm) distributions of atmospheric aerosols at a traffic site during the winter period. The average Mass in Media Aerodynamic Diameter (MMAD) of suspended particles is 0.99 μm this study. As for the ultra fine and nanometer (nanometer) particle mode, the composition order for these major ions species was SO42− NH4+ NO3− Mg2+ Ca2+ Na+ K+ Cl−. An ion Chromatography (DIONEX-100) was used to analyze major anion species, Cl−, NO3−, SO42− and cation species, NH4+Na+, K+, Ca2+Mg2+. Their concentrations were also extracted from various particles size modes (nanometer (nanometer), ultra fine, fine and coarse). The results obtained in this study also indicated that the average portions for the major ionic species (SO42−, NH4+ and Mg2+) in the nanometer (nanometer), ultra fine, fine and coarse particulate modes are about 34%, 37%, 63% and 30%, respectively at this traffic sampling site during the winter period.  相似文献   

10.
This study describes the chemical composition of dry deposition collected at a highway traffic site in central Taiwan during daytime and nighttime periods by using a dry deposition plate (DDP) and water surface sampler (WSS). In addition, the characterization for mass and water-soluble species of total suspended particulate (TSP), both PM2.5 and PM10, was studied at the study site from August 22 to November 30, 2006. Dry deposition fluxes of ambient air particulates and inorganic species (Na+, NH4+, K+, Mg2+, Ca2+, Cl−, NO3− and SO42−) were analyzed by Ion Chromatography (DIONEX-100).Results of the particulate dry deposition fluxes and mass concentrations are higher in the water surface sampler with respect to the dry deposition plate used in this study. Statistical results also showed the average dry deposition flux of the ionic species (Na+, NH4+, K+, Cl−, NO3− and SO42−) obtained by the DDP and WSS displayed significant differences. Also, the average concentrations of Mg2+ and, Ca2+ were statistically the same at this study site.  相似文献   

11.
We present the first application of a multi-stage impactor to study volcanic particle emissions to the troposphere from Masaya volcano, Nicaragua. Concentrations of soluble SO4 2–,Cl–, F–, NO3 –, K+, Na+,NH4 +, Ca2+ and Mg2+ were determined in 11 size bins from 0.07 m to >25.5 m. The near-source size distributions showed major modes at 0.5m (SO4 2–, H+,NH4 +); 0.2 m and 5.0 m (Cl–) and 2.0–5.0 m(F–). K+ and Na+ mirrored the SO4 2– size-resolvedconcentrations closely, suggesting that these were transported primarily asK2SO4 and Na2SO4 in acidic solution, while Mg2+ andCa2+ presented modes in both <1 m and >1 m particles. Changes in relative humidity were studied by comparing daytime (transparent plume) and night-time (condensed plume) results. Enhanced particle growth rates were observed in the night-time plume as well as preferential scavenging of soluble gases, such as HCl, by condensed water. Neutralisation of the acidic aerosol by background ammonia was observed at the crater rim and to a greater extent approximately 15 km downwind of the active crater. We report measurements of re-suspended near-source volcanic dust, which may form a component of the plume downwind. Elevated levels ofSO4 2–, Cl–, F–,H+, Na+, K+ and Mg2+ were observed around the 10 m particle diameter in this dust. The volcanic SO4 2– flux leaving the craterwas 0.07 kg s–1.  相似文献   

12.
Summary We measured ionic compounds in rain and fog at two remote sites in the South Island of New Zealand and at two sites in the Fichtelgebirge, F. R. of Germany. In the Fichtelgebirge high concentrations of H3O+, NO 3 – , SO 4 2– and NH 4 + indicate an anthropogenic impact, whereas in New Zealand concentrations were generally very low except for seasalt derived ions such as Na+, Cl– and Mg2+ at one site near the coast which receives precipitation from maritime sources. Remarkable differences occur in the acidity of hydrometeors in New Zealand and the Fichtelgebirge. The low pH values of the Fichtelgebirge (pH 4.2) are due to an excess of strong mineral acids, whereas the acidity of rain and fog in New Zealand is controlled by dissolved CO2 (pH 5.6). In the Fichtelgebirge, acidity in fog is much higher than in rain, whereas no difference could be observed in New Zealand due to marine influences and the lack of strong mineral acids. Rain of different trajectories of air flow in New Zealand is accompanied by a wide range of ionic concentrations.
Zusammenfassung An zwei entlegenen Meßstellen der Südinsel Neuseelands und an zwei Meßstellen im Fichtelgebirge haben wir die Ionen im Regen und Nebel gemessen. Die Luftverschmutzung im Fichtelgebirge ist gekennzeichnet durch hohe Konzentrationen von H3O+, NO 3 – , SO 4 2– und NH 4 + . Die Ionenkonzentrationen im neuseeländischen Niederschlagswasser waren durchwegs sehr gering mit Ausnahme von Na+, Cl– und Mg2+, die aus Seesalzen stammen und nur in einer küstennahen Meßstelle bei günstigen Wetterlagen bestimmt werden konnten. Große Unterschiede bestehen in der Azidität der Hydrometeore. Während im Fichtelgebirge starke Mineralsäuren niedrige pH-Werte (pH 4.2) bewirken, wird die Azidität des Regens und des Nebels an den neuseeländischen Meßstellen durch gelöstes CO2 kontrolliert (pH 5.6). Im Fichtelgebirge ist die Azidität im Nebel erheblich höher als im Regen. Im Gegensatz dazu konnten wir keinen Unterschied in der Azidität zwischen Nebel und Regen in Neuseeland beobachten, was wir mit dem marinen Einfluß und dem Fehlen starker Mineralsäuren erklären. Unterschiedliche Trajektorien der atmosphärischen Strömung in Neuseeland unterscheiden sich zugleich in ihren Ionenkonzentrationen im Regen.

With 6 Figures  相似文献   

13.
High volume bulk aerosol samples were collected continuously at three Antarctic sites: Mawson (67.60° S, 62.50° E) from 20 February 1987 to 6 January 1992; Palmer Station (64.77° S, 64.06° W) from 3 April 1990 to 15 June 1991; and Marsh (62.18° S, 58.30° W) from 28 March 1990, to 1 May 1991. All samples were analyzed for Na+, SO 4 2– , NO 3 – , methanesulfonate (MSA), NH 4 + ,210Pb, and7Be. At Mawson for which we have a multiple year data set, the annual mean concentration of each species sometimes vary significantly from one year to the next: Na+, 68–151 ng m–3; NO 3 – , 25–30 ng m–3; nss SO 4 2– , 81–97 ng m–3; MSA, 19–28 ng m–3; NH 4 + , 16–21 ng m–3;210Pb, 0.75–0.86 fCi m–3. Results from multiple variable regression of non-sea-salt (nss) SO 4 2– with MSA and NO 3 – as the independent variables indicates that, at Mawson, the nss SO 4 2– /MSA ratio resulting from the oxidation of dimethylsulfide (DMS) is 2.80±0.13, about 13% lower than our earlier estimate (3.22) that was based on 2.5 years of data. A similar analysis indicates that the ratio at Palmer is about 40% lower, 1.71±0.10, and more comparable to previous results over the southern oceans. These results when combined with previously published data suggest that the differences in the ratio may reflect a more rapid loss of MSA relative to nss SO 4 2– during transport over Antarctica from the oceanic source region. The mean210Pb concentrations at Palmer and Marsh and the mean NO 3 – concentration at Palmer are about a factor of two lower than those at Mawson. The210Pb distributions are consistent with a210Pb minimum in the marine boundary layer in the region of 40°–60° S. These features and the similar seasonalities of NO 3 – and210Pb at Mawson support the conclusion that the primary source regions for NO 3 – are continental. In contrast, the mean concentrations of MSA, nss SO 4 2– , and NH 4 + at Palmer are all higher than those at Mawson: MSA by a factor of 2; nss SO 4 2– by 10%; and NH 4 + by more than 50%. However, the factor differences exhibit substantial seasonal variability; the largest differences generally occur during the austral summer when the concentrations of most of the species are highest. NH 4 + /(nss SO 4 2– +MSA) equivalent ratios indicate that NH3 neutralizes about 60% of the sulfur acids during December at both Mawson and Palmer, but only about 30% at Mawson during February and March.  相似文献   

14.
Using the chemical composition of snow and ice of a central Greenland ice core, we have investigated changes in atmospheric HNO3 chemistry following the large volcanic eruptions of Laki (1783), Tambora (1815) and Katmai (1912). The concentration of several cations and anions, including SO 4 2– and NO 3 – , were measured using ion chromatography. We found that following those eruptions, the ratio of the concentration of NO 3 – deposited during winter to that deposited during summer was significantly higher than during nonvolcanic periods. Although we cannot rule out that this pattern originates from snow pack effects, we propose that increased concentrations of volcanic H2SO4 particles in the stratosphere may have favored condensation and removal of HNO3 from the stratosphere during Arctic winter. In addition, this pattern might have been enhanced by slower formation of HNO3 during summer, caused by direct consumption of OH through oxidation of volcanic SO2.  相似文献   

15.
Inorganic ions and trace metals in total suspended particles were measured during the period 2006–2007 at four sites; three urban sites in the Mexico City Metropolitan Area (MCMA) and one nearby rural site in the state of Morelos. SO42−, NO3−, Cl− and NH4+ ions were analyzed by ion chromatography; Na+, K+, Ca2+ and Mg2+ by flame atomic absorption spectroscopy, and Al, Cd, Cr, Mn, Pb and V by an atomic absorption spectrometer with a graphite furnace attachment. The results indicated that SO42− was the most abundant ion. All trace elements except Mn and V showed statistically significant differences between sampling sites. Pearson's correlation applied to all data showed a high correlation among SO42−, NO3− and NH4+, indicating a common anthropogenic origin. In addition, the correlation observed between Ca2+ and Al indicated a crustal origin, as supported by the enrichment factors. Over the total sampling period, significant differences in particles and trace metals were found between sites and meteorological seasons. To gain a better insight into the origin of trace metals and major inorganic ions, a Principal Component Analysis was applied to the results for six trace metal and eight inorganic ions.  相似文献   

16.
The paper presents monitoring results and environmental pollution assessment for the Gdask-Sopot-Gdynia Tricity (Poland), based onanalysis of precipitation. Precipitation samples were collected over a period of 12 months (January–December 1998) at ten locations in the Tricity. The following selected ions were determined in the samples:SO4 2–, F–, Cl–, NO3 –,PO4 3–, NH4 +, Na+,Mg2+, Ca2+, K+. The results were subjected to full statistical evaluation. Values of the parameters determined were correlated with each other. An attempt was made to explain co-occurrences of certain ions and the significance of their mutual effects. Pollutant concentrations and loads in precipitation were also correlated with data on wind direction and temperature in the region.Deposition of pollutants was very high in spring due to the prevailing air circulation patterns and low temperatures. Analysis of the correlations between co-occurring ions confirmed the significant impact of the location (sea coast) on the composition of rain water. Ionic ratios in rainwater were similar to those observed for sea salt samples. In addition, heavy traffic was most probably responsible for high concentrations of various forms of nitrogen and sulphates in the vicinity of major highways.  相似文献   

17.
A total of 48 precipitation samples have been collected from individual precipitation events at the Nam Co Monitoring and Research Station for Multisphere Interactions (Nam Co Station, 30°47′N, 90°58′E; 4730 m a.s.l) located in the central Tibetan Plateau from August 2005 to August 2006. All samples were analyzed for major cations (NH4+, Na+, K+, Ca2+ and Mg2+) and anions (Cl−, NO3− and SO42−), conductivity and pH. Precipitation pH values ranged from 6.03 to 7.38 with an average value of 6.59. The high pH is due to large inputs of crustal aerosols in the atmosphere, which contain a large fraction of carbonate. Ca2+ is the dominant cation in precipitation with an average value of 65.58 μeq L− 1 (4.91–301.41 μeq L− 1), accounting for 54% of the total cations in precipitation. HCO3− is the predominant anion, accounting for 62% of the total anions. When compared with data from a snow pit in the Zhadang Glacier 50 km away (5800 m a.s.l), major ion concentration in precipitation at the Nam Co Station is much higher due to local aerosol inputs. Correlation and empirical orthogonal function (EOF) analysis indicate that regional crustal aerosols and species from combustion emissions of residents are the major sources for these ions, lake salt aerosols from the Nam Co nearby and regional mineral aerosols from dry lake sediments are secondary sources, and sea salt contribution is the least due to the long distance transport.  相似文献   

18.
We use a global atmospheric chemistry transport model to study the possible influence of aqueous phase reactions of peroxynitric acid (HNO4) on the concentrations and budgets of NOx, SOx, O3 and H2O2. Laboratory studies have shown that the aqueous reaction of HNO4aq withHSO– 3aq, and the uni-molecular decomposition of the NO4 – anion to form NO2 – (nitrite) occur on a time scale of about a second. Despite a substantial contribution of the reaction of HSO– 3aq with HNO4aq to the overall in-cloud conversion of SO2 to SO4 2–, a simultaneous decrease of other oxidants (most notably H2O2) more than compensated the increase in SO4 2– production. The strongest influence of heterogeneous HNO4 chemistry was found in the boundary layer, where calculated monthly average ozone concentrations were reduced between 2% to 10% andchanges of H2O2 between –20% to +10%compared to a simulation which ignores this reaction. Furthermore, SO2 was increased by 10% to 20% and SO4 2–depleted by up to 10%. Since the resolution of our global model does not enable a detailed comparison with measurements in polluted regions, it is not possible to verify whether considering heterogeneous HNO4 reactions results in a substantial improvement of atmospheric chemistry transport models. However, the conversion of HNO4 in the aqueous phase seems to be efficient enough to warrant further laboratory investigations and more detailed model studies on this topic.  相似文献   

19.
We assessed the rainwater chemistry, the potential sources of its main inorganic components and bulk atmospheric deposition in a rural tropical semiarid region in the Brazilian Caatinga. Rainfall samples were collected during two wet seasons, one during an extremely dry year (2012) and one during a year with normal rainfall (2013). According to measurements of the main inorganic ions in the rainwater (H+, Na+, NH4 +, K+, Ca2+, Mg2+, Cl?, NO3 ?, and SO4 2?), no differences were observed in the total ionic charge between the two investigated wet seasons. However, Ca2+, K+, NH4 + and NO3 ? were significant higher in the wetter year (p < 0.05) which was attributed to anthropogenic activities, such as organic fertilizer applications. The total ionic contents of the rainwater suggested a dominant marine contribution, accounting for 76 % and 58 % of the rainwater in 2012 and 2013, respectively. The sum of the non-sea-salt fractions of Cl?, SO4 2?, Mg2+, Ca2+ and K+ were 19 % and 33 % in 2012 and 2013, and the nitrogenous compounds accounted for 2.8 % and 6.0 % of the total ionic contents in 2012 and 2013, respectively. The ionic ratios suggested that Mg2+ was probably the main neutralizing constituent of rainwater acidity, followed by Ca2+. We observed a low bulk atmospheric deposition of all major rainwater ions during both wet seasons. Regarding nitrogen deposition, we estimated slightly lower annual inputs than previous global estimates. Our findings contribute to the understanding of rainfall chemistry in northeastern Brazil by providing baseline information for a previously unstudied tropical semiarid ecosystem.  相似文献   

20.
A method for the estimation of the reaction probability of the heterogeneous N2O5+H2O 2HNO3 reaction using the deposition profile in a laminar flow tube, in which the walls are coated with the condensed aqueous phase of interest, is presented. The production of gas phase nitric acid on the surface followed by its absorption complicates the deposition profiles and hence the calculation of the reaction probability. An estimation of the branching ratio for this process enables a more appropriate calculation to be carried out. Reaction probabilities of N2O5 on substances including some normally constituting atmospheric aerosols, NaCl, NH4HSO4, as well as Na2CO3 are estimated and found to depend on relative humidity and characteristics of the coating used. These fell within the range (0.04–2.0)×10–2.  相似文献   

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