Physicochemical Characteristics And Source Apportionment Of Atmospheric Particulate Matter In Huainan Coal Mining Subsidence Area

In order to make certain the microscopic morphology,chemical composition and pollution characteristics of atmospheric particles in the coal mining subsidence area of Huainan,the samples(TSP,PM₁₀0 and PM_2.5)of Huainan winter heating period and summer haze period were collected in December 2016 and May 2017 respectively.The atmospheric particulate matter The contents of heavy metals?As,Cd,Mn,Pb,Hg,Cu,Zn,Ni,V and Al?and the concentrations of water soluble ions(Na⁺,K⁺,Mg²⁺,Ca²⁺,Cl^-,SO₄^2-,NO₃^-and F^-)were measured.The microscopic morphology and mineral composition of the particles were analyzed.The source of the atmospheric particles was analyzed and the effect of the special weather on the particles was also explored.The main results are as follows:1)The pollution levels of atmospheric particulate matter in Huainan coal mining subsidence area were relatively severe,and the average concentrations of TSP,PM₁₀and PM_2.5.5 in winter heating period were 307.95?g/m³,241.05?g/m³ and 133.11?g/m³,respectively,and were 389.84?g/m³,313.26?g/m³ and 230.62?g/m³ during the summer haze period,and both of them all exceeding the national air quality standards.Compared with the winter heating period,haze pollution in summer was even more serious.2)Zn,Mn and Pb are the main heavy metals in the atmospheric particulate matter of Huainan,and the three elements account for more than 82%of the total metal elements.Arsenic exceed the national standard limits both in winter and summer,and Mn and Ni also showed a different degree of over-standard phenomenon.After precipitation,the content of heavy metals in atmospheric particles were decreased in some degree.The heavy metals showed different characteristics during the day and night due to the changes of pollution sources.3)The main water-soluble ions in winter and summer are both SO₄^2-,NO₃^-and Cl^-.The three kinds of ions account for over 81%of the total water-soluble ions.After the rain,the concentration of each ions were decreases in direfent degrees,and the scavenging effect of NO₃^-was particularly prominent after precipitation.The changes of water-soluble ions concentration was complex between day and night,compared to daytime,the concentration of Cl^-and Na⁺was decreased during nighttime,while the concentration of SO₄^2-and NO₃^-was increased relatively,and the changes of NO₃^-were particularly outstanding.The rest ions had no obvious changes during day and night.4)According to the enrichment factor method,the enrichment degrees of Cu,Zn,As,Cd,Hg were relatively high.The EF value tend to increase with the decreasing of the particle size.In winter,the value of[NO₃^-]/[SO₄^2-]in TSP,PM₁₀0 and PM_2.5.5 were0.92,0.92 and 1.18,respectively,and were 1.82,2.10 and 2.11,respectively,in summer,This indicating that the contributions of mobile source and stationary source to particulate matter were equivalent in winter,and the moving source was the main source in summer.Through factor analysis method,it is found that the atmospheric particulates in Huainan subsidence area mainly come from industrial pollution,traffic emissions,coal combustion and dust.5)The results of SEM showed that the types of atmospheric particulates in Huainan coal subsidence area are mainly mineral particles?accounted for 40.79%?,followed by soot aggregates?35.55%?,coal fly ash?19.74%?and unknown particles?3.95%?.XRD analysis showed that the minerals in the subsidence area were mainly silicates,sulfates,carbonates and oxides.Silicate minerals included quartz,saponite,muscovite,kaolinite,chlorite;sulfate minerals were present as gypsum and ammonium gypsum;carbonate minerals as calcium carbonate and calcite;oxide minerals were potassium manganese oxide.6)By analyzing the size distribution of PM₁₀0 and PM_2.5,it was found that the proportion of PM₁₀0 particles smaller than 3?m was 92.59%and the peak value was0.5-1?m,accounting for 41.67%of PM₁₀.In PM_2.5,the particles smaller than 1?m accounting for 79.03%and the peak value was 0.3⁰.4?m,accounting for 33.87%of PM_2.5.Compared with the three-mode modal of particles,the atmospheric particles in the subsidence area of Huainan coal are mainly concentrated in the accumulation mode.