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

2.
Precipitation samples at an urban Chicago site and a nearby suburban site were compared in order to examine the influence of emissions within a large urban area on local precipitation chemistry. Precipitation samples were collected from June 1981 to May 1982, initially for events and subsequently weekly, and precipitation-weighted concentrations (PWCs) of the major chemical constituents were calculated from concurrent urban-suburban pairs of samples, stratified according to the estimated mixed-layer wind quadrant. Overall, PWCs at the urban site were higher than those at the suburban site for Ca2+, Mg2+, NH4+, NO3 and Cl; approximately equal for Na+ and SO42−; and lower for H+. For precipitation in southwesterly flow, in which the suburban site was upwind of the urban site and most urban emissions, PWCs of all species except Na+ were higher at the urban site. For the few precipitation cases in northeasterly flow, however, differences between sites did not have a pattern consistent with a reversal in the upwind-downwind relationship.  相似文献   

3.
Chemical composition of precipitation in Albany, NY from July 1986 to December 1988 has been studied. Mean volume-weighted concentrations (μeqℓ−1) were: acidity, 104.0; alkalinity, −63.7; SO42−, 52.8; NO3, 29.8; Cl, 5.6; F, 0.50; NH4+, 19.3; Ca2+, 6.5; Mg2+, 2.8; Na+, 3.5; and K+, 1.4. Mean pH was 4.2 . Seasonal patterns were pronounced for most species. Concentrations of H+, SO42−, NO3, NH4+ and Ca2+ peaked in the summer and spring. Deposition was related to rainfall amount by a power law relationship in which the exponent of the equation was ∮.6. Wet SO42− deposition was 2.35 keq ha−1 over a 30-month period. The SO42− and NO3 deposition rates observed at Albany indicate that transport from midwestern sources have a major influence at this site. On the average, free H+ ion concentrations determined from pH measurements accounted for 51% of the measured total acidity. There were unknown species, most likely organic acids, that could contribute to the acidity. Correlation and regression analyses indicated that major anions, SO42− and NO3, were closely associated with H+ and NH4+ ions. Factor analysis revealed four common factors which are related to fossil-fuel combustion, sea spray, cement factory and biomass burning.  相似文献   

4.
Rainwater samples in S. Paulo city were collected on an event basis from October 1983 to October 1985 covering two dry and two rainy periods. Bulk samples only were obtained. At the same site and period, fine, coarse and inhalable particles were also collected. Na+, Ca2+, K+, Mg2+, NO3, SO42− and NH4+ contents were determined in rainwater samples, while Na, Ca, K, Cl and S concentrations were measured in aerosol samples. Rainwater is slightly acid (mean pH = 5.0), and contains high concentrations of Ca2+, NO3, SO42− and NH4+. Dry and wet fluxes and washout ratios were determined for some elements. Results obtained suggest that the atmospheric composition in this city is strongly influenced by anthropogenic sources.  相似文献   

5.
Wet precipitation was collected in Thessaloniki, Greece, during the period March 1989–December 1990 by using an automatic wet-only precipitation sampler.Rainwater samples were analysed for major cations (H+, NH4+, Na+, K+, Ca2+, Mg2+) and anions (Cl, NO3, SO42−), in addition to acidity and conductivity measurements. The majority of rain had a neutral or alkaline character as a result of neutralization, primarily caused by calcareous soil dust and secondarily by atmospheric ammonia. In all rain, SO42− concentration exceeded NO3 concentration. The contribution of maritime sources to the total SO42− concentration was very low (<2%).The chemical composition of precipitation was analysed in conjunction with meteorological variables (season of the year, precipitation type, airflow patterns) to evaluate temporal variations and chemical source influence. Rain caused by weak, localized flows showed the highest acidity and the minimum influence of neutralization processes.  相似文献   

6.
As part of the second Arctic Gas and Aerosol Sampling Program (AGASP-II), Arctic aerosol samples were collected by the NOAA WP-3D aircraft in spring 1986. The samples were analyzed in bulk and individual-particle form, using ion chromatography (IC) and electron microscopy (EM), respectively. Information on the chemical composition of the aerosol as determined by various techniques is presented, as well as morphology, concentration, and size distribution data obtained from individual particle analyses. For most flights, a stratospheric sample and a haze profile samople were collected. Haze samples exhibited greater particle concentrations than stratospheric samples, the highest concentrations in haze reaching ∼103 cm−3 (non-volatile particles > 0.05 μm diam). Sulfur was consistently observed to be a major element in both large and small particles in haze samples. Crustal elements such as Si, Al, K, Ca and Fe were often present in significant concentrations together with S. Particles that did not emit X-rays, possibly organic or sooty C, were observed in significant concentrations in both tropospheric and stratospheric samples. Chemical spot tests confirmed that SO42− was the major S-containing species and that NO3 was not nearly as prevalent as SO42− in the Arctic aerosol particles. The mass concentrations of major anions (Cl, SO42− and NO3) and cations (Na+, K+, NH4+, Ca2+ and Mg2+) in the bulk aerosols were determined using IC. The ratios between ion concentrations, e.g. Ca2+/Na+, SO42−/Na+ and Cl/Na+, may serve as indicators of aerosol origins and mixing status of various air masses. Aerosols collected on six flights demonstrated variability of particle characteristics in relation to sources and transport of Arctic haze.  相似文献   

7.
Atmospheric dry deposition to branches of Pinus contorta and P. albicaulis was measured during summer 1987 in a sub-alpine zone at Eastern Brook Lake Watershed (EBLW), eastern Sierra Nevada, California. Results are presented as deposition fluxes of NO3, SO42−, PO43−, Cl, F, NH4+, Ca2+, Mg2+, Na+, K+, Zn2+, Fe3+, Mn2+, Pb2+ and H+, and compared with other locations in California and elsewhere. Deposition fluxes of anions and cations to the pine branches were low, several times lower than the values determined near the Emerald Lake Watershed (ELW), another sub-alpine location in the western Sierra Nevada. The sums of deposition fluxes of the measured cations and anions to pine surfaces were similar, in contrast to the ELW location where the sums of cation fluxes were much higher than the sums of anion fluxes. A strong positive correlation between depositions of NO3 and NH4+, as well as SO42− and Ca2+, suggested that large portions of these ions might have originated from particulate NH4NO3 and CaSO4 deposited on pine surfaces. An estimated total N dry deposition (surface deposition of NO3 and NH4+ and internal uptake of NO2 and HNO3) to the forested area of the EBLW was 29.54 eq ha−1 yr (about 414 g H ha−1 yr−1).  相似文献   

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

9.
Rainwater and atmospheric bulk deposition samples were collected at a station on the rooftop of the Research Institute of King Fahd University of Petroleum and Minerals in Dhahran. Continuous sampling was carried out manually throughout the rainy season between December 1987 and February 1988, and for one rainfall event in March 1987. A total number of 13 samples were collected and investigated for pH and dissolved ionic composition using inductivity coupled plasma emission spectrometry (ICP) and ion chromatography (IC). The range and volume-weighted average pH were 5.1–7.2 and 5.48, respectively. Significant negative linear correlations were observed between the precipitation pH and rain depth, and between pH and the summation of dissolved {(Ca2+ + Mg2+)−(SO42− + NO3 + NO2)} (in μeqℓ−1). The ionic summation also correlated negatively with rain depth. The ionic abundance in rainwater (in μeqℓ−1) expressed in concentration order showed the general trend SO42− > HCO3−1 = Cl = NO3 > NO2 for anions and Ca2+ > Na+ > Mg2+ > NH4+ > K+ > H+ > Sr2+ for cations. Good mass balance between cations and anions was observed. Total NO3 contribute equally to precipitation acidity as SO42− and Ca2+ plus Mg2+ in alkaline suspended particulates from natural sources are the major ions which buffer the acidity of precipitation. The NH4+ ion which is also present plays an insignificant role in the acid/base equilibrium of rainwater.  相似文献   

10.
不同植被类型及土壤对径流水化学特征的影响   总被引:2,自引:1,他引:1  
在不同植被类型覆盖条件下,对降雨形成地表径流和地下径流的化学成分变化及其与土壤剖面性质的关系进行分析,结果表明:地表径流和地下径流的化学特征与雨水基本相同,阳离子主要以Ca2+为主,离子排序为Ca2+>K+>Na+>Mg2+>NH4+,阴离子以SO42-为主,SO42->NO3->Cl-.降雨形成地表径流和地下径流后,各成分浓度发生了明显的变化,水体中主要的阴阳离子如Ca2+、Mg2+、K+、Na+、SO42-、Cl-等浓度增加,与雨水相比为内贮型化学成分,地下径流中Ca2+、Mg2+、SO42-和Cl-增加的幅度显著高于地表径流.相关分析结果显示,地下径流pH受到土壤pH的强烈影响,受土壤胶体吸附的影响,水体中Ca2+、Mg2+、K+、Na+等阳离子与土壤交换性阳离子之间一般呈负相关的关系,由于阴离子容易随水流失,水体中SO42-、NO3-和Cl-与土壤相关离子之间普遍呈正相关关系.  相似文献   

11.
Estimates of external and internal sources of ions in net througfall deposition were derived for a deciduous and coniferous canopy by use of multiple regression. The external source component appears to be dominated by dry deposition of Ca2+, SO2 and NO3 during dormant and growing seasons for the two canopy types. Increases in the leaching rates of K+ and Mg2+ during the growing season reflect the presence of leaves in the deciduous canopy and increased physiological activity in both canopies. Internal leaching rates for SO42− doubled during the growing season presumably caused by increased physiological activity and uptake of SO2 through stomates. Net deposition of SO42− in throughfall during the growing season appears highly dependent on stomatal uptake of SO2. Estimates of SO2 deposition velocities were 0.06 cm s−1 and 0.13 cm s−1 for the deciduous and coniferous canopies, respectively, during the dormant seasons, and 0.30 cm s−1 and 0.43 cm s−1 for the deciduous and coniferous canopies, respectively, during the growing season. For the ions of major interest with respect to ecosystem effects, namely H+, NO3 and SO42−, precipitation inputs generally outweighed estimates of dry deposition input. However, net throughfall deposition of NO3 and SO42− accounted for 20–47 and 34–50 per cent, respectively, of total deposition of those ions. Error estimates of ion sources were at least 50–100 per cent and the method is subject to several assumptions and limitations.  相似文献   

12.
The chemistry of bulk precipitation was measured from November 1983 to September 1987 at El Verde in the Luquillo Experimental Forest, Puerto Rico. Wet-only precipitation was also analyzed as part of the National Atmospheric Deposition Program from 1984 to 1987. Volume-weighted mean pH was 5.14 in bulk precipitation and 5.12 in wet precipitation. Concentrations of most species were correlated negatively with weekly rainfall. Sea salt aerosols contributed most of the Na+, Cl, Mg2+ and K+ found in wet and bulk precipitation; sulfate and calcium, however, were derived primarily from non-sea salt sources. Due to the high rainfall (3.4 m annually during the study period) and close proximity of the study site to the ocean, deposition rates of the major cations and anions were high relative to many other tropical sites. Precipitation chemistry at El Verde appears to be affected by several factors. During summer, Saharan dusts contribute a significant portion of the excess Ca2+, K+ and Mg2+. During winter months, cold fronts may transport SO42− and NO3 from North America and the western part of Puerto Rico to the sampling site.  相似文献   

13.
沙尘天气对兰州市PM10中主要水溶性离子的影响   总被引:3,自引:3,他引:0  
王芳  陈强  张文煜  郭勇涛  赵连彪 《环境科学》2014,35(7):2477-2482
利用在线监测仪器MARGA在兰州大学盘旋路校区对兰州市大气PM10中水溶性离子进行监测,监测期间(2011-04-01~2011-06-30)有15 d出现沙尘天气.兰州市PM10中主要水溶性离子物种为Ca2+、SO2-4和NO-3.扬沙天气期间NO-3和NH+4的浓度比非沙尘期间低,说明沙尘天气对当地人为源所排放污染物具有清除作用.沙尘天气期间,作为土壤污染源标识物的Mg2+、Na+和Ca2+离子都有明显增加,Na+和Mg2+相关系数为0.520,Na+和Ca2+相关系数为0.659,Mg2+和Ca2+相关系数为0.671,而非沙尘天气期间三者的相关系数并不高,Na+和Mg2+相关系数为0.065,Na+和Ca2+相关系数为0.131,Mg2+和Ca2+相关系数为0.163,说明沙尘天气期间三者之间具有相同的污染源,主要来自于土壤风沙尘,而非沙尘天气期间三者来源不同.Cl-的浓度在扬沙天气明显高于浮尘和非沙尘天气期间,说明外来的土壤风沙尘是Cl-的主要来源.  相似文献   

14.
In order to understand the concentration and deposition levels of the major ions in Shimane, on the Japan Sea coast where precipitation chemistry data are scarce, the precipitation was collected at three sites (Matsue, Gotsu and Masuda) from April 1985 to March 1988.The mean precipitation chemistry was very close to each other except for the seasalt concentration. Masuda showed a halved seasalt contribution compared with the other sites. The volume-weighted annual pH mean at each site ranged from 4.6 to 4.9. Nitrate to SO4−2 equivalent ratios were in the range of 0.2 and 0.4 throughout the year. Ammonia and calcium species are interpreted to have neutralized approximately 70% of the original sulfuric and nitric acids.The annual depositions of the major ions in g m−2y−1 were as follows: H+; 0.023–0.037, NH4+; 0.57–0.68, Ca2+; 0.51–0.92, SO42−; 3.29–5.04, NO3; 1.20–1.70. These levels are of the same intensity as corresponding values of JEA network results.  相似文献   

15.
The chemical composition of winter and spring cloud water sampled at 1620 masl elevation on Mt Rigi in central Switzerland was dominated by NO3, SO42−, NH4+ and H+. A wide range of concentration levels was observed, with maxima of 3700, 1800 and 4600 micronormal for NO3, SO42− and NH4+, respectively. Concentrations at a lower elevation (1030 masl) site on the mountain were higher due to lower cloud liquid water contents and higher pollutant levels at that site. The lowest pH observed was 2.95; large concentrations of NH3 in the region prevented pH values from falling even lower. A comparison of simultaneously sampled cloud water and precipitation revealed much higher concentrations for most species in the cloud water, except in one case of extreme precipitation riming when the concentrations in the two phases converged. An exception to the pattern was H+; at times the precipitation was more acidic than the cloud water. The chemical composition of the cloud drops varied with drop size. Drops smaller than 10 μm diameter were enriched in NO3, SO42− and NH4+ relative to larger drops. Since the larger drops are the ones most effeciently captured by snow crystals, knowledge of their composition is essential to understanding the chemical implications of accretional growth of precipitation.  相似文献   

16.
A paired comparison was performed on 2 years of precipitation chemistry data from Meridian and Newton, MS. The Meridian site is in violation of several National Atmospheric Deposition Program siting criteria, whereas the Newton site, 35 km west, is mostly in compliance. The two sites are compared through the use of volume-weighted means, deposition, logarithmic distributions, boxplots, paired t-tests, the nonparametric Wilcoxon test, and a form of linear regression analysis that accounts for cases in which both populations are subject to error. Results indicate Meridian has higher concentrations of all measured ions except NH4+. Elevated NH4+ concentrations at Newton are most likely due to the location of the site in a cattle pasture. Significant differences (95% confidence level) were found for Cl, Na+, K+, Ca2+ and Mg2+. SO42− was found to be borderline significant.  相似文献   

17.
中国西南酸雨区降水化学特征研究进展   总被引:10,自引:3,他引:7  
周晓得  徐志方  刘文景  武瑶  赵童  蒋浩 《环境科学》2017,38(10):4438-4446
西南酸雨区为我国主要酸雨沉降区,且是全球三大喀斯特集中分布区之一.本文将该区9个地点的降雨资料进行了总结、整理和分析,数据包括pH值和主离子成分(Cl~-、SO_4~(2-)、NO_3~-、Ca~(2+)、NH_4~+、Mg~(2+)、K~+、Na~+).该地区降雨中的主要阴离子为SO_4~(2-)和NO_3~-,主要阳离子为Ca~(2+)和NH_4~+.与我国其它地区相比,其酸性离子、碱性离子和总离子浓度均普遍高于东南地区、而低于我国北方地区.西南酸雨区主要以pH值为4.5~5.6的弱酸性降雨为主,占总降雨频次的58%左右.根据酸、碱性离子的相关性、中和因子等分析结果,该区雨水中的酸性物质可能受到了碱性离子的中和作用,其中起主要中和作用的离子为Ca~(2+)和NH_4~+.将该区雨水pH值和酸、碱性离子浓度与我国其它地区进行对比研究发现,西南酸雨区降雨受到的中和作用要强于东南地区,但弱于北方地区的降雨.通过对西南酸雨区降雨中主要离子来源的分析和估算,降雨中的酸性离子SO_4~(2-)和NO_3~-主要来自于人为污染;99.7%的Ca~(2+)和84.0%的Mg~(2+)为陆源贡献,这可能与西南地区碳酸盐岩广泛分布有关.  相似文献   

18.
A side-by-side comparison of the Rotating Arm Collector (RAC) and the Caltech Active Strand Cloudwater Collector (CASCC) was conducted at an elevated coastal site near the eastern end of the Santa Barbara Channel in southern California. The CASCC was observed to collect cloudwater at rates of up to 8.5 ml min−1. The ratio of cloudwater collection rates was found to be close to the theoretical prediction of 4.2:1 (CASCC:RAC) over a wide range of liquid water contents (LWC). At low LWC, however, this ratio climbed rapidly, possibly reflecting a predominance of small droplets under these conditions, coupled with a greater collection efficiency of small droplets by the CASCC. Cloudwater samples collected by the RAC had significantly higher concentrations of Na+, Ca2+, Mg2+ and Cl than those collected by the CASCC. These higher concentrations may be due to differences in the chemical composition of large vs small droplets. No significant differences were observed in concentrations of NO3, SO42− or NH4+ in samples collected by the two instruments.  相似文献   

19.
Monthly mean chemical composition of aerosol with diameter less than 8 μm was identified in Sapporo in 1982. The mass of aerosol was made up of nine components: elemental C, organics, SO42−, NO3, NH4+, Cl, Na+, soil particles and water. The concentrations of carbonaceous particles (elemental C and organics) was relatively high (12.7–16.0μ m−3) in autumn and winter (October–February) due to emission from domestic heating and comprised 36–41% of total aerosol mass. Higher concentration of soil particles was observed in spring (March–May) (9.7–13.1 μg m−3) and comprised 22–29% of total aerosol mass due to suspension by strong wind. On the other hand, the concentration of excess SO42− (non-sea salt SO42−), which ranged from 2.6–5.2 μg m−3, did not change remarkably with season, and the fraction of excess sulfate increased to 21% in summer (July–August) probably due to photochemical transformation from SO2. Nitrate concentration was far less than that of SO42− throughout the year in Sapporo.  相似文献   

20.
会仙岩溶湿地地下水主要离子特征及成因分析   总被引:6,自引:6,他引:0  
以我国最大的低海拔岩溶湿地会仙岩溶湿地为研究区,对该区丰水期、平水期和枯水期共采集的27组地下水样品中常规离子进行检测和分析,在分析会仙岩溶湿地地下水主要离子化学特征和不同时期变化基础上,运用单指标污染标准指数法对不同时期地下水进行污染评价,利用多元统计、Gibbs模型和离子比例关系识别地下水主要离子成因.结果表明,研究区内岩溶地下水主要为弱碱性淡水,Ca2+和HCO3-为优势离子.不同时期地下水主要离子总浓度顺序为:平水期 > 丰水期 > 枯水期,枯水期水质优于丰水期和平水期.地下水中K+和NO3-主要受含水层空间分布差异影响,Mg2+、SO42-、NO2-、NH4+和TDS受时空尺度综合作用,Na+、Ca2+、HCO3-和Cl-为水体中较稳定离子.受碳酸盐岩控制,丰水期、平水期和枯水期地下水化学类型具有高度一致性,HCO3-Ca水占比分别为77.78%、77.78%和88.89%.地下水主要受SO42-、NO3-和NO2-污染,NO3-出现极严重程度污染样点,SO42-在丰水期和平水期出现较重污染样点.地下水化学组分主要受水岩作用控制,Ca2+和HCO3-主要来源于方解石风化溶解,少量水点受白云岩、白云质灰岩及硫铁矿控制导致Mg2+和SO42-浓度偏高,K+、Na+、SO42-、NO3-和Cl-部分来源于大气降水,Na+和Cl-部分来源于当地居民生活,K+与种植施用的钾肥相关,NO3-主要来源是化学肥料.  相似文献   

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