Water-soluble Inorganic Ions Compositions And Pollution Characteristics Of PM₁₀ And PM_2.5 In Nanchong City

In order to understand the pollution characteristics of inhalable particles(PM10)and fine particulate matter(PM2.5)in Nanchong city,this paper collected the PM10 and PM2.5samples in a typical month of spring,summer,autumn,autumn and winter in 2015.The mass concentrations of PM10 and PM2.5 and the concentration of water-soluble inorganic ions of F-,NO3-,SO42-,K+,Mg2+,Na+,Ca2+and NH4+were measured and the main meteorological and gaseous pollutants were collected during sampling.The Annual and different seasons pollution characteristics of PM10 and PM2.5 mass concentrations and water-soluble inorganic ions were Analyzed.The relationship between the main meteorological and the gaseous pollutants with PM10 and PM2.5 mass concentration were analyzed.The systematic studied the Cation and anion balance,combination modes of the secondary water soluble ions and source apportionment of water-soluble inorganic ions in PM10 and PM2.5.The main conclusions were as follows:The annual average mass concentrations were(78.4±36.2)and(55.4±30.5)?g/m3 of PM10 and PM2.5 in Nanchong,respectively.They were 1.12 times and 1.58 times more than national secondary annual average concentration standard respectively.The annual mean value of PM2.5/PM10 was 0.71,indicating that the PM2.5 is an important component of PM10,and they were well correlations.The seasonal variations of mass concentrations in PM10 and PM2.5 were both present the characteristics of winter>fall>spring>summer,and the mass concentration of winter was much higher than fall,spring and summer.The seasonal variations of value PM2.5/PM10 was present the characteristics of fall>summer>winter>spring.The mass concentrations of PM10 and PM2.5 were both present negative correlation relationship with precipitation,wind speed and visibility,indicating that with precipitation,wind speed and visibility increasing the mass concentrations of PM10 and PM2.5 reduced.The mass concentrations of PM10 and PM2.5 had a weak negative relationship with temperature,and had a little influence with relative humidity.The mass concentrations of PM10 and PM2.5 were both present the significant positive correlation relationship with NO2,SO2 and CO,indicating that with the mass concentrations of NO2,SO2 and CO increasing the mass concentrations of PM10 and PM2.5 increased.The annual average mass concentrations of total water-soluble inorganic ions were(28.60±12.70)and(21.32±11.09)?g/m3 of PM10 and PM2.5 in Nanchong,respectively.The mass concentrations contribution of total water-soluble inorganic ions in PM10 and PM2.5 were 36.50% and 38.49% respectively,and It's an important part of PM10 and PM2.5.The seasonal variations of the mass concentrations of total water-soluble ions in PM10 and PM2.5 were both present the characteristics of winter>fall>summer>spring,the highest mass concentration appeared in autumn and winter.The average mass concentrations of SO42-,NO3-,NH4+and Ca2+were both the highest in PM10 and PM2.5,they were both accounted for more than 90% of total water-soluble ions in PM10 and PM2.5.The results of the cation and anion balance analysis showed that the PM10 was alkaline in spring and autumn,and the PM10 was close to neutral in summer and winter,During the whole sampling period,the PM10 was weakly-alkaline and close to neutral,and the PM2.5 was acid of inordinately in each season.The SO42-,NO3-and NH4+both in PM10 and PM2.5 showed that NH4HSO4 and NH4NO3 were the combination modes.The annual mean value of the nitrate oxidation rate and the sulfur oxidation rate of the PM10 and PM2.5 were 0.12 and 0.55,0.10 and 0.48,respectively,indicating that the NO3-was not obvious quadratic transformation process in PM10 and PM2.5,while the SO42-was obvious quadratic transformation process.The PM10 and PM2.5 were mainly affected by stationary sources.The correlation analysis showed that the PM10 source was more complex than PM2.5,the SO42-and NH4+,K+ and Na+ were well correlations in PM2.5,Ca2+ and Mg2+ were well correlations in PM10,suggests that they may have the same source.The principal component analysis showed that the secondary pollution sources,combustion sources,soil emissions and industrial sources were the major sources of PM10 and PM2.5 in Nanchong,and the secondary pollution sources had a bigger contribution to PM2.5 than PM10,the soil emissions had a bigger contribution to PM10 in spring and fall.