Characteristics Of Chemical Elements In Rain Water And Cloud/Fog Water At Mt.Lushan

Trace elements in rain water and cloud/fog water had become a hot issue of the international research. This study selected Mt.Lushan for the chemistry observations of rain water and cloud/fog water, contents included the acidity and chemical characteristics of elements. Through this observation we can understand the situation of the local air pollution, chemical characteristics of rain water and cloud/fog water, as well as the source of pollutants about Lushan. Because of the unique topography and location of Mt.Lushan, this observation has guiding significance to the research of trace elements in rain water and cloud/fog water in southern China.This observation was from August to September in2011, during the observation there were eleven rain events and fifteen cloud/fog events, which collected eleven rain water samples and fifty-one cloud/fog water samples. The chemical analysis include pH, characteristics of chemical elements (major elements:Na, Mg, K, Ca and trace elements:Al, V, Cr, Mn, As, Se, Ba, Pb).The rain water was acidic with the volume weighted mean (VWM) pH4.2and about73%of samples could be identified as strongly acidified rain. Studies had shown that the acidification was increasing year by year but the increase trend was slowing. The acidity of rain water at Mt.Lushan was much higher than other sites abroad. The highest concentration of elements were Ca and Na which had a small difference in concentration; the highest concentration of trace element was Al. Compared with the observations of other sites around the world, the concentrations of trace elements in rainwater at Mt.Lushan was relatively high. Four sources of Elements in rain water were crustal, marine, traffic pollution and metallurgical industry pollution.The volume weighted mean (VWM) pH of water/fog water was3.73and about82%of samples were strongly acidified. Studies had shown that the acidification was increasing year by year but the increase trend was slowing. The acidity of cloud/fog water at Mt.Lushan was much higher and more changeable than other sites abroad. The highest concentrations of elements were Ca and Na; the highest concentration of trace element was Al.The concentrations of V, Cr, As, Pb were relatively higher than other sites. It showed a good correlation between pH and the concentration of trace heavy metal in cloud/fog water samples by correlation analysis. Positive Matrix Factorization analysis showed that37.79%of elements were contributed by marine source,35.07%of the elements came from the soil,8.45%of the elements came from the rock source,5.02%of the elements came from fossil fuels combustion,4.06%of the elements were contributed by the metallurgical industry.The concentration of chemical elements in cloud/fog water was6.2times than that in rain water at Mt.Lushan, the ratio of different elements were1.33times-12.47times.In case of rainfall and cloud occurred at the same time, the concentration of chemical elements in cloud/fog water was3.1times than that in rain water, the ratio of different elements were1.04times-75.7times.Continuous rainfall could remove particulate matter in the atmosphere, the nature of cloud/fog water would approach the rain water. By comparison of the cloud under different case, we could find that the impact of the rainfall effect was more obvious to atmospheric particulate bearing crustal elements.Back trajectory analysis showed that the strong acid cloud air masses in Mt.Lushan mainly came from, the most acid mass came from the Pearl River Delta industrial zone,the acidity of cloud came from northern and northeastern were relatively lower. The elemental of long-range transport were much higher than the local air mass. Air mass came from northern and north-west with the highest concentration of elements, which was lower frequency and shorter duration, bring less impact on the Mt.Lushan; The elemental concentrations of Cloud mass came from Pearl River Delta industrial zone were higher and that came from local were relatively cleaner; the highest frequency of air mass was came from sea direction, which had higher acidity and lower elemental concentrations.