The Research On Urban Precipitation Chemistry And The Characteristics Of Representative Pollutants In Hunan Province

Acid rain problem becomes more and more serious in China since 1990s', especially in Hunan province situated in Central-south China. The history, present situation, researching field and the harms of acid rain pollution is simply introduced and summarized. With the severer acid rain pollution in urban, the status in quo of pollution, formation of factors are analyzed based on the natural and social conditions of Hunan province. In this thesis, the concentrations, emitted quantity, geographical distribution of SO2 and the trend of those in the future are estimated and predicted in Hunan. The precipitation chemistry and the seasonal and spatial characteristics of pH value of rainwater in Hunan province are discussed. Take Changsha city for example, the atmospheric pollution and acid rain pollution are also researched. The time and spatial variation law of main air pollutants such as SO2, NOX(NO2), TSP, and the characteristics of the representative chemical compositions of rainwater are analyzed and discussed based on the three monitoring stations in Changsha in the period of 1990-2001. And the influence of air pollutants on the formation of acid rain is analyzed. The pH value of rainwater is predicted based on the GM (1, 1) model. The results show that the type of acid rain is the typical H2SO4 type, the larger emission intensity of SO2 is confined to the industrial regions located in the Central and West-south part of Hunan. The emission amount of SO2 will gradually increase if the effective treatment measures are not taken. SCU2', NO3~, Ca2 + , NH4+ are the major chemical compositions of atmospheric precipitation in Hunan province, accounting for larger than 60% of the total ionic amount of rainwater. The distribution of lower pH value of rainwater coincides to the distribution of catchments of the four river systems of Hunan (XiangJiang river, ZiJiang river, YuanJiang river and LiShui river), showing that the pollutants discharged from the local industrial sources the main causes of the severe atmosphere pollution, of some regions in Hunan province. The predicted results show that the acidity of rainwater will be further acidified in the future ten years if the effective measures are not adopted. In the last part of the paper, the comprehensive and effective measures to prevent and treatment acidrain pollution are presented based on the characteristics of acid rain and the variation of the pollutants. Improving the energy structure, researching and generalizing on the low cost desulphurization techniques and equipments, intensifying and strengthening the environmental management are capable of improving the prevent and treatment of atmospheric pollution. The research is significative and instructive in some extent to prevent and control acid rain pollution of Hunan province.