Pollution Characteristic Of Acid Precipitation In Zhejiang And Its Multi-dimension Analysis

It has been more than one hundred years since people pay attention to acid rain problem. The cognizing degree to acid rain of people in countries in the world is gradually increasing including each aspect from mechanism of acid rain formation to entironment destory since Britisher first found acid rain in 1872. Especially in recent thirty years, a large number of scholars have done embedded research on harm of soil ecosystem, forest ecosystem, farm ecosystem and city ecosystem caused by acid rain. They found acid rain can made soil salt ion leaching , poisonous substance dissolving, wood withered, forest output decreasing, cropper output reducing , cropper quality debasing and building cankerous. Therefore, acid rain and water eutrophication have become two of ecological problems that influence human survival.Acid rain pollution is global as one part of global water circulation. East Acia including south China together with North America and North Europe is called most serious acid rain aera in the world. It is acid gases produced by energy consumption that caused acid precipitation spreading and aggravation. Earth atmosphere has its own environmental capacity like water, but polluted air is more difficult to be puritfied than polluted water because we have no capability to build an all-around air decontaminating factory so far. Pollution level of wet precipitation directly reflects the degree of air pollution as natural air decontaminating technics.Considering ecological hazard which acid precipitation brings to south China area, dualism as air pollution indicator and clarifier and special geographic position which Zhejiang located in as the Changjiang River delta industry district, it has important significance to study the pollution characteristic of acid precipitation in Zhejiang. Characteristics of precipitation in Zhejiang are researched hereon including ion composition and spatial variability, relationship between pollution elements and pollution meteorology factor. 1. Ionic composition of rainwater and frequency distribution of ions Cations occupy 52.1% of total ions and anion occupy 47.9% of total ions. Other 1.2% imbalance parts may be composed of organic acids and other unknown components.Concentration composition on an equivalent basis for major anions are as follows: SO42-(27.8%)>C1-(13.2%)> NO3-(6.9%). Equivalent ratioes of SO42-/Cl- and SO42-/NO3- are 2.1 and 4.0 respectively.Characteristics of geographic distribution of ion in rainwater are concluded as follows: the concentrations of Na+and Cl- in litttoral are higher than that in inland, the concentrations of SO42- ,NO3- and Ca2+ which mainly come from anthropogenic in industry district are higher than that in underdevelopment district.Monitoring data from 1997 to 1999 show that the distribution of rainfall, electric conductivity and pH value are positively skewed and their skewness values(parenthesized) are ranked as follows: raifall ( 2.890 ) > electric conductivity (1.579 ) > pH ( 0.612 ) . Kurtosis analysis indicates that the peakedness of rainfall and electric conductivity are greater than the normal distribution, k>0 (leptokurtic) while the peakedness of pH is less than the normal distribution, k<0 (platykurtic).Statistics on precipitation chemistry for all sampleing sites indicate that the distribution of main ions in rainwater are positively skewed and platykurtic with the same ranking of skewness and kurtosis: Mg2+>K+>NH4+>SO42-> Na+> H+> Ca2+ >NO3->Cl-. The distribution of Cl-, NO3-, Ca2+' approach normal distribution. Distribution characteristics of ions in rainwater show the biggish spatial variability of precipitation pollution.2. Chemical characteristics of rainwater constitutionThe ratio of the standard deviation to the mean concentration of ions in rainwater show the variability of ion concentration in precipitation is different from each other and SO42-, NO3- and NH4 are the components relatively uniform. Sulfur oxides and nitrogen oxides are relatively uniform in air because of long distance transmition of the...