Methanesulfonic Acid In The Atmosphere And Its Contribution To The Acid Rain

Two cruises were carried out in the North Yellow Sea during summer (July 18～August 7, 2006) and winter (December 31, 2006～January 17, 2007) and two cruises were carried out in Shandong coastal sea during summer (August 14～23, 2006) and winter (December 17～25, 2006) to determine the content of methanesulfonic acid (MSA) in the atmosphere and its contribution to acid rain. The main conclusions are obtained as follows:1) Analysis method about MSA is improved on the basis of literature. Extraction percentage of MSA in the filters containing samples ranged from 100 % to 102 %.The time of measurements of positive ions (Na+, NH4+, K+, Mg2+ and Ca2+ ) and negative ions ( MSA, NO2-, SO42-, NO3- and PO43- ) are ascertained by ICS-1000.2) Concentration of Total Suspended Particulate(TSP) conforms to the first area and the first order standard of the State Ambient Air Quality Standard. The air quality on the sea is good. The concentration of TSP is only one aspect of Environmental Assessments. Concentrations of TSP whether in atmosphere of Shandong coastal Sea or North Yellow Sea are higher in winter than in summer, because it has more rainfall in summer than in winter. The atmosphere on the Yellow Sea (including Shandong coastal sea and the North Yellow Sea) is largely dependent on the extent of the contamination source on the land.3) Concentrations of TSP in the atmosphere increase gradually from May to December, which is due to the effect of wind. Wind makes the TSP move from the inland to Qingdao coastal sea, as well as its concentration increases by month. This law is similar to the north Yellow Sea and Shandong coastal sea. Concentration of TSP conforms to the State Ambient Air Quality Standard of the second-rate area and the second-class standard. Therefore, Qingdao is a place fit for human habitation.4) The results about the North Yellow Sea and Shandong coastal sea indicate that concentrations of MSA in TSP are high in summer and low in winter, in correlation with the temperature and light intensity, in correspondence with the literature. This is mainly due to higher concentrations of DMS in summer (DMS of Yellow Sea is higher in summer than in winter) than in winter. MSA is one oxidation product of DMS. MSA is used to estimate the contribution of nss-SO42-. We find that the contribution of DMS in the atmosphere to the nss-SO42- on the North Yellow Sea is far higher in summer than in winter.5) Concentrations of MSA in Qingdao atmosphere is the highest in summer ( July), lower in the Spring and Autumn (May, June and October), and the lowest in winter (November and December).6) By sampling Qingdao rain water, we can find that MSA contributes to total ions in the rain can not be ignored, the contribution rate is about 0.89%. This is likely related to the release of ocean. The contribution of MSA and nss-SO42- to the rainwater are about 48.18%.The mean concentration of MSA in Qingdao rainwater is 0.130 mg/L. The concentration of MSA in the rainwater of North Yellow Sea is 0.132 mg/L. The contribution rate is obviously lower in Qingdao rainwater than in North Yellow Sea rainwater. Absolute contribution amount is in the same level in Qingdao as in North Yellow Sea.7) Qingdao acid rain is still a serious problem which needs to cause great attention by the relevant administration departments. Focused on environmental issues, we expect a better and more beautiful environment in Qingdao.8) From the results of Qingdao rainwater, we find that the contribution of sea salt to the ions of rainwater has the same law with the time. The contribution rate is the highest in July and August. It is likely duo to the wind force, the ocean contributes more marine elements to the atmosphere on the coastal sea in summer, so the sea salt contribution rate is high in rainwater.In short, through four cruises in summer and winter in Shandong coastal sea and North Yellow Sea, TSP, rainwater and MSA concentrations are objectively analyzed. The environment is scientifically evaluated. The relation between MSA, temperature and weather is summarized. This paper offers fundamental evidence on scientific research of global sulfur cycle, acid rain monitoring and environmental monitoring.