Characteristics Of Water Soluble Ions In Marine Aerosols Collected Over The Marine Boundary Layer On The Routes Of Chinese National Antarctic Research Expedition

Marine aerosol samples collected during the 25th and 26th Chinese National Antarctic Research Expedition (CHINARE) were analyzed for compositions and concentrations of water soluble ions. The sources for all ions were indentified. The major results were showed as followings:(1) The major concentration for water soluble ions in the marine aerosols in the 25th CHINARE was higher than that in the 26th CHINARE. Cl^-, Na⁺, SO₄^2-, NO^3-, and Mg²⁺ were the primary water soluble ions. Sea salt was the primary component and sulfate was the second one in the marine aerosols .(2) The concentration of sea salt appeared the peak around 40°S during both cruises. A good relationship between wind speed and sea salt, suggesting wind speed would determine the concentration under an equation of linear regression between ln(mseasalt) and U. Secondary aerosol NO3- and NH4+ were greatly impacted by anthropogenic sources, their high concentration appeared in marginal seas; The lower concentrations of non-sea-salt sulfate (nss-SO₄^2-) were found over the open ocean or the Southern Ocean, while the higher concentrations were observed over the marginal seas; On the contrary, latitudinal distributions of methane sulfonic acid (MSA) had the tendency of increasing from northern hemisphere to southern hemisphere, especially rising at the south of 60°S. This study showed that the marine primary production may be one of the important factors that affect the MSA concentration distributions; According to the significantly linear relationship between MSA and MSA/nss-SO₄^2- and good exponential decay relationship between MSA/nss-SO₄^2- and air temperature during both cruises, it could be concluded that the contribution of biogenic sulfur to nss-SO₄^2- were possibly controlled by the oxidation of dimethylsulfide (DMS) and air temperature.(3) The concentration of chloride ions was depleted in different degrees during both cruises. In the 25th CHINARE, the chloride depletion was about 7.1%⁴4.9%, while it was about 0.3%²4.4% in the 26th CHINARE.(4) The constituents of Na+, Mg²⁺, Cl^- and Br^- in sea salt presented significant correlation relationship each other, which showed their common marine sources; The secondary aerosol ions nss-SO₄^2-, NO^3- and NH4+ presented significant positive correlation each other during any cruise, which showed that they had similar sources and they may exist as NH₄NO₃, NH4HSO4, (NH₄)₂SO₄. Therefore, the water soluble ions in marine aerosols collected on the route of both Antarctic expedition cruises could be derived from marine sources and anthropogenic sources, as well as the MSA mostly was contributed from marine biogenic sources.