Studies On Temporal And Special Distributions Of Atmospheric Mercury In Taiwan Strait Inshore Areas

Mercury can cycle and transform among the atmosphere, land and ocean because of its special physical and chemical properties. Mercury can not only deposit near the sources, but also can transport to long distance with air. In recent years, anthropogenic emissions of mercury appear to decrease in Europe and North America while increase in Asia. There are more and more researches about different species of atmospheric mercury in China and foreign countries. Compare to the researches were made in the inland areas, the researches of atmospheric mercury in coastal cities are less, especially for the coastal areas in China.To understand the concentration levels, temporal-spatial variation and influencing factors of atmospheric mercury in coastal areas of southeast China, this research monitored the different species of atmospheric mercury in Taiwan Strait inshore areas. The goals of this study are as follows:(1) to understand the concentrations levels and temporal-spatial variation of total gaseous mercury(TGM) and total particulate mercury(TPM),(2) to understand the concentrations levels and temporal-spatial variation of mercury in rainwater (including total mercury(THg), dissolved mercury(DHg) and reactive gaseous mercury(RGM)),(3) to investigate the correlations of atmospheric mercury(including TGM and TPM) with meteorological parameters and atmospheric pollutants.The measurements of atmospheric mercury in Taiwan Strait inshore areas suggested that the concentrations of TGM and TPM were significantly higher than those of the background regions of North Hemisphere, but lower than the concentrations of mercury mine areas and coal heating areas. Different regions had different characters because of geographical locations and anthropogenic sources. This indicated that human activities had great influence in atmospheric mercury, especially there were obvious pollution sources around sampling sites, such as the waste gas of industries and fishers.Influenced by wind speed, wind direction and other meteorological parameters, there was an obvious monthly and seasonal trends for atmospheric TGM and TPM. TGM and TPM were lower in warm months and higher in cold months, lower in summer and autumn and higher in winter and spring. Temperature inversion and haze are easy to occur in cold months, atmospheric pollutants are difficult to diffuse in regions. The results also suggested that atmospheric mercury from north China in winter and spring could significantly effect the atmospheric quality of coastal areas in Taiwan Strait. The concentrations of atmospheric mercury in winter and spring were higher than summer and autumn.Measurements of mercury in rainwater indicated that DHg was the major mercury phase while RGM accounted for little proportion. THg in rainwater was higher in winter and lower in summer, which was related to the concentration of mercury in atmosphere, rainfall depth and rain frequency. In summer, the concentration of mercury was lower, rainfall was large and it was frequent to rain. In winter, the concentration of mercury was higher, rainfall was little and the time interval between two precipitation was long. Because of different locations, the influences of region and long-term transport caused by meteorological parameters (such as wind speed, wind direction) were different. Under special meteorological parameters, the anthropogenic emission of atmospheric mercury from Yangtze river delta, Pearl river delta, Thailand and Laos could influence the atmospheric mercury in coastal areas of southeast China.THg in precipitation were detected when the rain was caused by typhoon. The results indicated typhoon could influence the concentration of mercury in rainwater. When typhoon transported from the ocean, the atmosphere can be purified by the clean air and the mercury in rain is low. When typhoon transported across the polluted area, pollutant transported to the sampling areas and high THg could be detected.