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降水酸度和化学组分垂直监测的初步分析 总被引:4,自引:0,他引:4
1986年6—9月,在无锡市近郊的锡惠公园内,在三个不同的高度上进行降水的同步采样,并对雨水的酸度、电导率和各种离子的含量作了测定。结果表明:降水酸度随着高度的增加而增强;电导率和雨水中离子的浓度则随着高度的增加而减小;通常上层减小得慢,下层减小得较快。碱性阳离子的结构在不同的高度上有明显的差异。另外,雨水对大气中污染物的冲刷作用,是一个重要的清除过程,下层比上层的冲刷作用更强。 相似文献
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云化学模式及其若干研究进展 总被引:1,自引:0,他引:1
本文从云的微物理过程、云中化学反应、云水、雨水对污染气体和气溶胶的清除过程,云化学模式等方面,总结介绍了近几年来云化学模式的若干研究进展。 相似文献
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分析了1985-1991年冬季雨雪的酸度及化学组份资料。结果表明,降雪的酸雪频率各年均有不同,但都比同季中降雨的酸雨频率低;降雪酸度也比降雨纸;降雪中弱酸性的酸雪出现次数最多,占总次数的4成;在酸雪中酸度值与电导率呈现显著的负相关。分析降雪的化学组份发现,降雪中SO4^2-含量越来越高,Cl^-含量呈下降趋势。阳离子中以NH4^+为主。 相似文献
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根据1995年12月~1996年1月新疆北部的5个采样点5次降雪过程中收集的资料,分析研究了降雪酸度及其化学组分的特征。 相似文献
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利用NASA/CERES发布的2001~2015年云参数资料,选取高层云、雨层云、层积云的云水含量和云粒子有效半径,统计分析了西南地区云参数的时空分布特征和变化趋势。结果表明:从年均空间分布来看,西南地区液水和冰水含量均东部高于西部,海拔低的地区高于海拔高的地区;高层云和雨层云液相和冰相云粒子有效半径在川西高原最大。从数值大小来看,雨层云液水和冰水含量最多,分别介于90~230 g/m2和100~300 g/m2,层积云最少,分别介于0~80 g/m2和0~60 g/m2;冰相云粒子有效半径高于液相2~6 μm。从季节分布来看,雨层云液水和冰水含量秋季和冬季偏高,夏季和春季偏少,高层云和层积云季节差异较小;液相云粒子有效半径均夏季最大。从变化趋势来看,西南地区各地液水和冰水含量均呈减少趋势,液相和冰相云粒子有效半径有呈减少或增加趋势。 相似文献
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Elevated concentrations of S(IV) and formaldehyde were observed in fog- and cloudwater at sites in California. The highest concentrations (up to 3 mM S(IV) and 0.7 mM CH2O) were measured at Bakersfield, during a prolonged period of repeated fog. In Bakersfield [S(IV)] generally exceeded [CH2O], while in the Los Angeles area the reverse was observed. The lowest concentrations of both species were observed at marine and high altitude sites away from local emissions. Equilibrium computations indicate that high concentrations of S(IV) cannot be achieved without the formation of S(IV)-RCHO adducts. 相似文献
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1999年夏季上海地区洪涝灾害的成因分析 总被引:1,自引:0,他引:1
着重从气候背景及南亚季风、南海季风、副热带高压、赤道辐合带和中纬度阻塞系统异常等方面分析了1999年上海地区夏季(6~8月)异常特多降水的成因,指出以上这些都是造成上海夏季降水特多的主要因素。 相似文献
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P. R. Salve T. Gobre H. Lohkare R. J. Krupadam A. Bansiwal D. S. Ramteke S. R. Wate 《Journal of Atmospheric Chemistry》2011,68(3):183-198
Studies on precipitation chemistry were carried out to understand the nature and sources of rainwater at Rameswaram and NTPC
Dadri, India representing coastal and industrial region during 2010. The rainwater samples, collected at these locations,
were analyzed for major ions and pH. The data were assessed for its quality. The pH of rainwater at two locations varied from
5.53 to 6.73 and 5.1–6.6, indicating alkaline nature except a few acidic events. The dominance of Cl− and Na+ were observed
in coastal environment whereas dominance of Ca2+ was seen in industrial environment. The nss-SO42- (37.9%) at Rameswaram is
less influenced by anthropogenic activities whereas nss-SO42- (72.5%) at NTPC Dadri is influenced by pollutants emitted by
anthropogenic sources. The ratio of H+/(NO3- + SO42-) was observed as 0.04 and 0.008 for Rameswaram and NTPC Dadri which is
close to zero, indicate 99.99% of acidity was neutralized in precipitation. Ca2+, NH4+ and Mg2+ play an important role in
neutralization of acidic ions in rainwater. For source identification, correlation matrix analysis was established, which
showed that in general, at both sites; correlation between the acidic ions SO42- and NO3- indicating their origin from similar
sources, because of the similarity in their behavior in precipitation and the co-emissions of their precursors SO2 and NOX.
The correlation coefficient of (SO42- + NO3-) vs (Ca2+) at Rameswaram and NTPC Dadri were 0.77 and 0.87 indicates that CaCO3
is the major neutralizing agent for both the region. Overall, the influence of marine, terrestrial and anthropogenic sources
was observed in the rain events. 相似文献
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Acid rain and alkalization in southwestern China: chemical and strontium isotope evidence in rainwater from Guiyang 总被引:1,自引:0,他引:1
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
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本文对上海市区1984年全年27个雾日的天气形势和有关气象要素的变化作了比较深入的分析。发现上海该年出现4种雾类即:锋面雾(占40.7%)、辐射雾(占29.7%)、平流辐射雾(占18.5%)和平流雾(占11.1%)。并指出上海城市雾具有下述三个主要特征:(1)近数十年来年平均雾日数有递减趋势,近8年年平均雾日比前20年减少14.4天;(2)在城市辐射雾和平流辐射雾出现前,出现城市湿岛的机率高达92.3%,可作为这两种雾的先兆。在秋冬季节,在这两种雾中,还出现雾天城市湿岛效应;(3)有相当多的低相对湿度城市“浊雾”。 相似文献
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介绍了民航华东气象中心开发的上海机场终端区AMDAR(Aircraft Meteorological Data Relay)资料实时显示系统,简述了系统的基本原理和工作流程;并统计了AMDAR资料的分布特征,对机场出现的雷暴、大风、冰雪等天气进行了实例分析。结果表明:上海机场终端区AMDAR资料实时显示系统直观、实用,有效地提高该资料的使用率;AMDAR资料时空分辨率高,但分布不均匀,资料97.4%集中在00:00—15:00UTC时段和67.3%集中在4km以下的中低空区域;系统能够提供连续的高空风温分布,也能够捕捉到高空中小尺度天气特征,在某些天气过程中能够为短临预报提供良好的客观依据和辅助手段,具有一定的实用价值。 相似文献
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Aqueous concentrations of ionic species observed in cloud water studies often have been in conflict with expectations from model predictions. These inconsistencies result from the size-dependent chemical composition of cloud drops during different stages in the lifetime of a cloud. To study this phenomenon, droplets of clouds need to be collected in different size ranges with high resolution in space and time. The only possibility for this kind of study is the use of an aircraft. Therefore, during the last several years, an attempt was made to develop a mobile cascade impactor, which can be installed outside an aircraft. The cloud water sampled in different size fractions can be transferred into the interior of the aircraft during the measuring flight. The collector is able to sample two size fractions. For continental clouds, the cutoffs are chosen to be >5 and >13.5 μm in diameter. For maritime clouds, the cutoff for the first stage could be shifted to 18.6 μm by lowering the nozzle speed. Prior to field application, the collector was characterized with the aid of “calibration fogs” produced in the laboratory with different drop sizes and different chemical compositions. The characterization included the examination of the cutoffs and the reliability of the sampling procedure with regard to the subsequent chemical analysis. With a collection period of 2 min, collection rates in the order of 0.1–1 cm3 min−1 can be obtained. The collector characterized in this manner was successfully used during measuring flights in clouds over northern Germany. Preliminary concentrations of NH4+, SO42− and Cl− found in the two size fractions of the cloud drops are presented. 相似文献