Chemical composition of wet precipitation of air pollutants: A case study in Karachi,Pakistan     

《Atmósfera》2014,27(1):35-46

Air pollution has been considered one of the most important environmental challenges because of its direct effect on ecosystems and human health. Temporal changes in the composition of 20 samples of rainwater in the arid region of Karachi, Pakistan during the southwest monsoon of 2009 have been monitored to carry out the indirect assessment of air quality. The study has been fulfilled with the aim of identifying the level of air pollution, and the relative contribution of possible anthropogenic activities. Metal ions were analyzed to predict health risks. Rain samples were found to be alkaline (pH 5.55-7.55) due to the influence of calcium and magnesium rich particles. Continuous rains in consecutive days showed a remarkable decline in air pollution while the dry season boosted up the level of pollution. Strong correlations of total dissolved solids with K⁺, Na⁺, Ca²⁺, Mg²⁺, and Cl⁻ were observed. A relatively weak correlation of total suspended particles with metals showed the possibility of some other particulate matters being suspended in the air. Principal component analysis and analysis of means were used to predict the anthropogenic source of pollution. This study will be helpful to formulate strategic planning and policies for controlling the level of air pollution in the city.  相似文献   

北方农牧交错带马铃薯沟垄集雨技术适宜性研究   总被引：1，自引：0，他引：1  

胡琦  潘学标  杨宁 《干旱区地理》2015,38(3)

北方农牧交错带是典型的雨养农业区,降水少且变率大,绝大多数农田缺乏灌溉条件,降水成为限制作物生产力的重要因素。以农牧交错带半干旱偏旱典型地区武川县为例,利用1960-2012年地面气象观测资料,对该地区马铃薯沟垄集雨技术适宜性进行了分析。结果表明:武川地区马铃薯全生育期内需水量为414.7 mm,平均水分亏缺为155.1 mm,占全生育期需水量的37.4%;马铃薯生育期内≥10 mm降水次数占18.5%,其降水量占总降水量的2/3左右,容易形成径流,有利于沟垄集雨集中有限降水用于作物生长;沟垄集雨可缓解北方农牧交错带半干旱偏旱地区马铃薯需水亏缺,丰水年、平水年和歉水年马铃薯全生育期裸地垄面径流深度分别为81.1 mm,49.0 mm和21.0 mm。在当地的气象条件和环境条件下,垄面为裸地时,种植马铃薯推荐采用的沟垄宽度比为1∶2.6,垄面覆膜时,推荐沟垄宽度比为1∶0.48。  相似文献   

绿化屋顶的产流规律及雨水滞蓄效果模拟研究   总被引：3，自引：0，他引：3  

唐莉华  倪广恒  刘茂峰  孙挺 《水文》2011,(4):18-22

建筑物屋顶作为城市的"第五面",是城市立体化绿化的重要方面。通过屋顶绿化植被和土壤层的蓄滞作用,可在一定程度上延缓产流时间,减少城市径流,并改善局地微气候条件。开展了绿化屋顶的人工降雨径流观测实验,通过对降雨、径流的观测分析了绿化屋顶的雨水滞蓄效果。建立了描述绿化屋顶降雨产流过程的一维入渗模型HYDRUS-1D,利用实验数据进行了模型的率定和验证;并应用模型模拟分析了降雨频率、土层厚度和土壤类型等因素对绿化屋顶雨水滞蓄效果的影响。实验和模拟结果表明,绿化屋顶具有较好的雨水滞蓄效果,10cm土层厚度的绿化屋顶在不同降雨条件下的蓄滞量可达到16.1～21.6mm;随着土层厚度的增加,蓄滞效果更明显;就雨水蓄滞效果而言,壤土比砂土和粉粘土更适合于绿化屋顶。本研究成果可为城市屋顶绿化的推广应用提供参考。  相似文献   

How important is the selection of computational analysis method to the accuracy of rainwater tank behaviour modelling?     

V. Grace Mitchell 《水文研究》2007,21(21):2850-2861

As the concept of sustainable urban water management is incorporated into the practice of urban water resource managers, actions, such as the utilization of roof runoff via rainwater tanks, which have multiple benefits, are increasingly being built into urban water systems. Modelling tools are frequently used to predict the yield from rainwater tanks and to estimate the storage capacity required to achieve a given potable supply reduction level, with these estimates used in both urban water resources policy development and engineering design. Therefore, it is important that the accuracy of commonly used models is understood. This paper investigates the impact of computational time step, computational operating rule, initial storage level, and the length of simulation period on the accuracy of the storage–yield–reliability relationship calculated using a simple rainwater tank behaviour model. Four time steps (ranging from 6 min to 24 h), two operational rules (supply before spillage and supply after spillage), two initial storage level states (empty and full), and three simulation periods (50 years, 10 years and 1 year) were applied to a wide range of rainwater tank system configurations and three different locations in Australia. It was found that the supply‐after‐spillage computational operating rule is preferable, while the ratio of the average demand volume in a single computational time step divided by the storage capacity (ΔD/S) can be used to assess whether a given combination of demand, storage, inflow, and computational time step will provide long‐term yield estimates that are within ± 5% of the values produced by a simulation that used a 50‐year time series of climate, 6‐min time step, and a supply‐after‐spillage operational rule (50‐6‐YAS). Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

Heavy metals in bog waters: An alternative way to assess atmospheric precipitation quality?   总被引：1，自引：0，他引：1  

Luca Bragazza   《Global and Planetary Change》2006,53(4):290

Ombrotrophic bogs are used to reliably assess past and present levels of heavy metal depositions through chemical analyses of peat layers. Instead, surface waters collected in ombrotrophic bogs were never tested as an alternative way to assess atmospheric precipitation quality, although the solely source of water in bogs is by atmospheric precipitation. In the present paper the reliability of bog water to mirror atmospheric precipitation quality has been tested. To this aim, heavy metal concentrations in bog water were compared to both rainwater chemistry, and tissue chemistry of Hylocomium splendens, a moss frequently used as biomonitor. Bog water was periodically sampled in three different microhabitats, i.e., a hummock, a carpet, and a hollow at two bogs, located in the south-eastern Alps of Italy. Microhabitats were selected in order to encompass a gradient of water table depth from relatively dry to relatively wet conditions, respectively. Basing on surface peat and bog water chemistry as well as on hydrological measurements, selected microhabitats were shown to be ombrotrophic, i.e., their mineral input was solely by atmospheric precipitation. Heavy metal concentrations in bog water did not differ significantly among microhabitats, with the only exception of Fe which showed significantly higher concentrations in hummock water. Because of the lack of rainwater chemical information for the study area, mean heavy metal concentrations in rainwater were obtained from a set of European stations monitoring atmospheric precipitation. A significant relationship was found between heavy metals in rainwater and bog water, further supported by the positive relationship between emission amounts of Cd, Cr, Cu, Zn, and Pb in Italy and the corresponding values in bog water during the study period. Concentrations of heavy metals in bog water were then compared with corresponding concentrations in H. splendens collected in the nearby of the study bogs. Moss chemistry has been here used as a proxy of atmospheric precipitation chemistry, basing on the reliability of mosses to mirror local precipitation chemistry as widely demonstrated by biomonitoring surveys. Bog water and moss tissues showed the same pattern of variation of concentrations, although moss tissues were characterised by higher absolute concentrations of heavy metals.  相似文献   

喀斯特森林雨水的地球化学特征——以贵州茂兰国家级自然保护区为例   总被引：2，自引：0，他引：2  

韩贵琳  唐杨  谭秋 《矿物岩石地球化学通报》2008,27(4)

贵州茂兰喀斯特原始森林地区25个雨水样品的化学组成研究表明,该区雨水的pH值为4．4～7．2,平均为5．1。雨水样品富NH4^＋、Ca^2＋和SO4^2-、C1^-。NH4^＋是最主要的阳离子,平均值为56．8／μmol／L,占阳离子组成的26％～74％,Ca^2＋次之,平均值为14．8μmol／L,NHg和Ca^2＋之和占了阳离子组成的71％～94％,SO4^2-是最主要的阴离子,平均值为39．2μmol／L,占了阴离子组成的69％～91％,CI一次之,平均值为9．5μmol／L。SO4^2-和C1-占了阴离子组成的71％～96％。与中国其他地区的雨水样品相比,茂兰地区雨水离子含量要低1～2个数量级;物质来源分析表明茂兰地区雨水中溶质主要来源于自然过程的输入,人为活动输入可以忽略不计。  相似文献   

Rainwater Chemistry and Wet Deposition over the Equatorial Forested Ecosystem of Zoétélé (Cameroon)     

L. Sigha-Nkamdjou  C. Galy-Lacaux  V. Pont  S. Richard  D. Sighomnou  J. P. Lacaux 《Journal of Atmospheric Chemistry》2003,46(2):173-198

Within the framework of IDAF (IGAC DEBITS AFRICA: International GlobalAtmospheric Chemistry/DEposition of Biogeochemically Important TraceSpecies/Africa) network, data analysis is realised on precipitation chemical composition collected in Zoétélé, in Southern Cameroon. This station, located atabout 200 km from the Atlantic Ocean, is representative of a so-called `Evergreen Equatorial Forest' ecosystem. An automatic wet-only precipitation collector was operated at the station from 1996 to 2000. The rainfall regime, associated with eastward advection of moist and cool monsoon air masses, amounts to an average of 1700 mm/year. Inorganic and organic content of the precipitation were determined by IC in 234 rainfall events, representing a total 4,583 mm of rainfall from an overall of 7,100 mm.The mean annual precipitation chemistry and wet deposition fluxes characteristic of an African equatorial forest are quantified. Typical atmospheric gases and particles sources influence the precipitation chemical content and the associated deposition of chemical species. Indeed, hydrogen concentration is the highest (12.0 eq.L^–1) of the IDAF measurements, leading to acid rains with a low mean pH 4.92. The mineral species are dominated by nitrogenous compounds (NH₄ ⁺:10.5 and NO₃ ^–: 6.9 eq.L^–1), Ca²⁺ (8.9 eq.L^–1) and SO₄ ^{2 –} 5.1 eq.L^–1. Relationship between Ca^{2 +} and SO₄ ^{2 –} indicated aterrigeneous particulate source and an additional SO₄ ^{2 –} contributionprobably due to swamps and volcano emissions. Na⁺ and Cl^–concentrations, around 4.0 eq.L^–1, seem very low for this site,accounting for the marine source. Besides, strong correlations between NH₄ ⁺/K⁺/Cl^– indicate the biomass burning originof these species. Accordingly, precipitation chemistry in Zoétéléis influenced by three major sources: biogenic emissions from soil and forest ecosystems, biomass burning from savannah, and terrigenous signature from particles emissions of arid zones; and three minor sources: marine, volcano and anthropogenic. In spite of the relatively low concentration of all these elements, the wet deposition is quite significant due to the high precipitation levels, with for example a nitrogenous compounds deposition of 34 mmol.m^–2.yr^–1.  相似文献   

黄土高原小流域雨水利用环境效应评价的方法与指标体系   总被引：8，自引：4，他引：4  

余海龙  吴普特  冯浩  汪有科 《中国沙漠》2005,25(1):50-54

 依据雨水利用的理论基础,分析了雨水利用系统的组成,从生态、经济和社会3方面建立了雨水利用环境效应评价指标体系,以及构建指标体系的程序、方法、原则、结构和内容。并且给出了相关指标的计算方法。在不同尺度上,评价的主导因素不同。依据这一特点和层次分析理论,提出了雨水利用环境效应评价过程。  相似文献   

苏州河初期雨水调蓄池控制溢流污染影响研究   总被引：17，自引：0，他引：17       下载免费PDF全文

徐贵泉  陈长太  张海燕 《水科学进展》2006,17(5):705-708

利用苏州河沿岸代表性排水系统雨季溢流水量水质监测以及调蓄池处理技术的实验研究成果,与数学模型研究有机结合,建立了苏州河水系水量水质模型和排水系统概化管网水力模型,系统研究了在8种1~12h设计降雨条件下,苏州河沿岸初期雨水调蓄池控制溢流污染的影响变化及其对苏州河水质的影响。  相似文献   

城市雨水管理信息系统的基本架构     

曾兵  谭海樵  王延霞  李洁 《水文》2007,27(6):39-41

城市化进程对区域可持续发展，特别是对城市的雨水管理提出了一系列新的挑战。为应对这一挑战，就必须立足于自然水文循环的维系，因地制宜地对城市雨水实施信息化、智能化管理。在分析涉及城市雨水管理的必要性、可行性的基础上，本文提出了城市雨水管理系统的基本框架。这一以城市雨水为管理对象的信息系统首先要具备的功能是与城市自然条件相关的信息输出和管理，如地形、地貌、植被、土壤等基础数据的数字化、信息化，进而要考虑与雨水管理直接相关的参数输出和管理，如城市的水文区位、土地利用现状、平均降雨量、最大降雨历时、最小无降雨历时等。空间分析模块是该信息系统的核心．城市雨水管理模式的选择和布局都是建立在对上述各种相关数据实施空间分析的基础之上的。不同雨水管理模式和设施的实际应用效果可借助本系统进行模拟并实现可视化。  相似文献