Chongqing City, The Main City Forest Precipitation Chemistry And Tieshanping Basin

The objects of this study were the broadleaf in Chongqing Environmental Monitoring Center which lies in Guan Yin Qiao and pinus forests which is representative in Tie Shan Ping area. This program analyzed the chemical character, dynamic change , the sources of ions and the character of nutritional elements of rainfall and canopy throughfall utilizing two different methods of sampling, and have compared with other studies home and foreign to investigate the environmental pollution condition of the two region. Also the study has distinguished the functions of dry deposition and vegetation interior circular (leaching and absorption) of throughfall, and deeply understood the mechanism of rainfall and forest canopy using equal volume method according to the characters in different periods.1, There was relatively obvious difference in acid rain frequency between suburb and the main city zone in Chongqing during 2004. Acid rain is adapted to diffuse forward suburb. We can know that rainfall EC was almost close at Tie Shan Ping site than at Guan Yin Qiao site and the annual rainfall amount was the same condition . The form of acid deposition was different at the two monitoring sites.2, The degree of pollution was higher at Guan Yin Qiao of Chongqing city than Tie Shan Ping suburb, and the highest degree of pollution at the two area was in winter. It is bulk precipitation that became major factors at suburb. The result of compare of throughfall and bulk deposition at Tie Shan Ping during 2004 and during 1998 was that throughfall was the major pollution form, and even aggravated from 1998 to 2004. We can know that throughfall was the most important pollution form of three pollution form.3, There was an phenomena that the rainfall acidified both in the city and suburb, and pH value was smaller in suburb than in the city. It can explain that acidification was bad in suburb. When rainfall pass through the canopy, there is the current that the rainfall is more acid, While it decreased when rainfall pass by the broadleafs. EC of rainfall is close in these two sits, but it is increase obviously in throughfall. The phenomenon of enrichment was found out in these two research sites, especially of Mg2+and K+ and Ca2tand S042" of anions.4^ The dynamic change of throughfall chemical components was that EC was decreased slowly and the fluctuant circs was same, but it appeared earlier in throughfall than in rainfall. The change of pH values was almost same to EC, while pH value was falling at the begin of rainfall, and throughfall was contrary. And the current of dynamic change of other major ions was decreased slowly with rainfall, and their concentration mostly decreased in the begin and they were low in the middle, and then rose in the end of rainfall. We must seen that all ions appeared almost synchronously peak value. The reason is the pollution that increases the concentration of all ions after raining out. So we should pay attention to the regional pollution because of sulfur dioxide.5> All the nutrients concentration in throughfall increased in different degrees compared with rainfall in the same condition except N in winter in Tie Shan Ping. Nitrogen (NH4+N) was absorbed mostly by branches and leaves , and it' s concentration became go down ,while other nutrient elements were leaching and enrichment in throughfall. N element in throughfall (rl, which showed that the nutritional elements were mainly from rainfall and leaves of vegetation after being leached. Otherwise, Mg element was influenced mostly by that leaching from vegetation in Tie Shan Ping, while K element in Guan Yin Qiao.6> The sequence show that DR value in throughfall and leaching content had the same tendency, which illuminated that rainfall had leaching effect for broadleafs canopy in Guan Yin Qiao. We can also find that N increased after passing through forest canopy, which was different from what we expected that it could be absorbed. Meanwhile we found concentration of nutritional elements (except Ca) decreased after rainfall passing through canopy. We consider that it was the tree species resulted in the difference. When the season of vegetation , the input of rainfall nutrition elements is that calcium is the biggest and phosphorus is the smallest. The input of all nutrition elements of rainfall is 44.33 percent of the input gross, and calcium is the major nutrition elements. While the input of throughfall nutrition elements is that calcium is the biggest and phosphorus is the smallest. But the order of nitrogen and kalium is different. The input of all nutrition elements of throughfall is 55.66 percent of the input gross, and calcium is the major nutrition elements either. The nutrition elements gross is 38. 88mg. I/1 of rainfall and 48. 82 mg. L"'of throughfall, and throughfall is the major form. The leaching amount of nitrogen and calcium is positive and others is contrary, and calcium element is the biggest, kalium is the smallest. The input of calcium and nitrogen is 18.75 percent and 19.38...