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1.
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   

2.
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   

3.
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   

4.
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   

5.
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   

6.
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   

7.
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   

8.
A comprehensive study on the chemical compositions of rainwater was carried out from June 2007 to December 2008 in Guiyang, a city located on the acid rain control zone of southwest China. All samples were analyzed for pH, major anions (F−, Cl−, NO3−, SO42−), major cations (K+, Na+, Ca2+, Mg2+, NH4+), Sr2+ and Sr isotope. The pH increase is due to the result of neutralization caused by the alkaline dust which contain large amount of CaCO3. It was observed that Ca2+ was the most abundant cation with a volume-weighted mean (VWM) value of 217.6 μeq/L (52.7–1928 μeq/L), accounting for 66% (39%–88%) of the total cations. SO42− was the most abundant anion with VWM value of 237.8 μeq/L (49.6-1643 μeq/L). SO42− and NO3− were dominant among the anions, accounting for 66%–97% of the total measured anions. The Sr concentrations vary from 0.01 to 0.92 μmol/L, and strontium isotopic ratios vary in the range of 0.707684–0.710094, with an average of 0.708092. The elements ratios and the 87Sr/86Sr ratios showed that the solutes of rainwater mainly come from weathering of carbonate and secondary dust input. Moreover, urbanization results in the calcium-rich dust increased and the high concentrations of alkaline ions (mainly Ca2+) have played an important role to neutralize the acidity of rainwater, leading to the increase of arithmetic pH mean value by 0.5 units since 2002. It is worth noting that the emission of SO2 and NOx from the automobile exhaust is increasing and is becoming another important precursor of acid rain now.  相似文献   

9.
In the present study, the wet and dry depositions of particulate NO3−, SO42−, Cl− and NH4+ were measured using a wet/dry sampler as a surrogate surface. Gas phase compounds of nitrogen, sulfur and chloride (HNO3, NH3, SO2 and HCl) were measured by an annular denuder system (ADS) equipped with a back up filter for the collection of particles with diameter ≤ 5 μm. Ambient concentrations of NO, NO2 and SO2 were also taken into consideration. Sampling was conducted at an urban site in the center of the city of Thessaloniki, northern Greece. The presence of the aerosol species was examined by cold/warm period and the possible compounds in dry deposits were also considered. Dry deposition fluxes were found to be well correlated with ambient particle concentrations in order to be used for the calculation of particle deposition velocity. Average particulate deposition velocities calculated were 0.36, 0.20, 0.20 and 0.10 cm s− 1 for Cl−, NO3−, SO42− and NH4+, respectively. Total dry deposition fluxes (gas and particles) were estimated at 3.24 kg ha− 1 year− 1 for chloride (HCl + p-Cl), 9.97 kg ha− 1 year− 1 for nitrogen oxidized (NO + NO2 + HNO3 + p-NO3), 5.32 kg ha− 1 year− 1 for nitrogen reduced (NH3 + p-NH4) and 15.77 kg ha− 1 year− 1 for sulfur (SO2 + p-SO4). 70–90% total dry deposition was due to gaseous species deposition. The contribution of dry deposition to the total (wet + dry) was at the level of 60–70% for sulfur and nitrogen (oxidized and reduced), whereas dry chloride deposition contributed 35% to the total. The dry-to-wet deposition ratio of all the studied species was found to be significantly associated with the precipitation amount, with nitrogen species being better and higher correlated. Wet, dry and total depositions measured in Thessaloniki, were compared with other countries of Europe, US and Asia.  相似文献   

10.
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   

11.
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   

12.
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   

13.
合肥市降水化学组成成分分析   总被引：5，自引：1，他引：4  
为研究合肥市降水的化学组成成分,于2010年4—9月在合肥市国家基本气象站设立了采样点,进行降水的采集,对降水化学组成成分进行了测定,并系统分析了化学组成成分的特点。结果表明:合肥降水中阴离子主要为SO24-,阳离子主要为NH4+和Ca2+,[SO24-]/[NO3-]当量浓度比值范围为1.23～6.33,大部分样本的比值<3,说明酸雨类型以硝硫混合型为主。降水的酸度与单一离子当量浓度的相关性并不明显,应该是受多种离子综合影响的结果,SO24-与NO3-,Ca2+与Mg2+,NH4+与SO24-,NH4+与NO3-均表现出较好的相关性。  相似文献   

14.
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   

15.
In this paper, the basic composition of fog and low cloud water are presented, resulting from the analyses of water samples from 111 fog/cloud events. The samples were collected at five sites located in various regions of the Czech Republic. Two sampling sites are in mountainous regions and three sites represent various urban areas. The mountain stations are located in two regions of the Czech Republic with different industry types. At all the sites, active fog collectors were employed. In the water samples, the conductivity, acidity (pH), cations (H+, Na+, K+, NH4+, Mg2+, Ca2+) and anions (F−, Cl−, NO3−, SO42−) were determined.A mean pH value of about 4.5 was obtained at mountain sites whereas the measurements in urban areas showed mean pH values from 4.9 to 6.4. The mean conductivity values in the samples from the two mountain stations were 137 and 191.5 μS cm−1. The samples from urban sites showed mean values between 127.7 and 654.4 μS cm−1. The maximum concentration means for the three dominant pollutants (expressed by the ratio mountain sites/urban sites) are 32.9/99.6 mg l−1 for NO3−, 32.5/192.9 mg l−1 for SO42− and 18.5/52.7 mg l−1 for NH4+. As expected, we found higher ion concentrations in the northern part of the Czech Republic where larger numbers of lignite-burning power plants, chemical factories and opencast lignite mines are located. A decrease in ion concentrations was observed at higher altitude sites, probably reflecting at least in part higher liquid water contents at these locations.  相似文献   

16.
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   

17.
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   

18.
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   

19.
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   

20.
In the present study, the precipitation near Büyükçekmece Lake, which is one of the important drinking water sources of Istanbul city, was studied during October 2001–July 2002. Seventy-nine bulk precipitation samples were collected at two sampling stations near the Lake (41°2′35″N, 28°35′25″E and 41°5′30″N, 28°37′7″E). The study comprised the determination of H+, Cl−, NO3−, SO42−, NH4+, Na, K, Mg, Ca, Al, Ba, Fe, Cu and Mn concentrations in bulk deposition rain event samples. The average volume-weighted pH value was found to be 4.81, which points out that the rain is slightly acidic. High sulfate concentrations were observed together with high H+ ion values. Sulfur emissions were the major cause for the observed high hydrogen ion levels. On the basis of factor analysis and correlation matrix analysis, it has been found that in this region, acid neutralization is brought about by calcium rather than the ammonium ion. The varimax rotated factor analysis grouped the variables into four factors, which are crustal, marine and two anthropogenic sources.  相似文献   

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