天津市大气颗粒物污染特征与来源构成变化

对1985年、2001年和2011年天津市颗粒物的粒径、化学组分以及污染来源的变化趋势进行了对比分析. 结果表明:天津市PM₁₀中细粒子所占比重逐渐增加,由1985年的<0.51升至2011年的0.57. PM₁₀中化学组分发生了明显改变,主要组分由单一的地壳元素发展为二次粒子、碳和地壳元素并重,1985年以地壳元素(Si、Al、Mg、Ca等)为主要组分,2001年以TC、Si、SO₄2-、Al、Ca为主要组分,2011年主要组分除TC、Si、SO₄2-、Ca外,还新增了NO₃-. 各主要组分质量浓度及其占ρ(PM₁₀)比例的变化多样,ρ(Si)所占比例先显著下降后保持平稳,其由1985年的28.7%降至2011年7.6%；碳组分所占比例由2001年的24.9%降至2011年17.9%；二次粒子质量浓度〔即ρ(SO₄2-)、ρ(NO₃-)之和〕所占比例由2001年的10.2%升至2011年的18.3%. 煤烟尘对天津市PM₁₀的分担率由1985年的45%降至2011年的22%,而开放源、二次粒子和机动车尾气尘对PM₁₀的分担率有所增加,三者分别由1985年的29%、6%和3%升至2011年的35%、16%和16%. 环境空气中对颗粒物有重要贡献的源类越来越多,颗粒物的污染特征由煤烟型过渡为混合型再过渡到复合型. 

Variations of Characteristics and Sources of Ambient Particulate Matter Pollution in Tianjin City

Variation characteristics of particle size, chemical composition and pollution source of the ambient particulate matter of Tianjin City in 1985,1and 2011were analyzed. The results showed that mass ratios of fine particulate matters to PM₁₀ were gradually increasing, from less than 0.51in 1985to 0.57in 2011. Chemical compositions of PM₁₀ significantly changed, evolved from single crustal elements to multiple crustal elements including carbonaceous matters and secondary particles. The dominant components of PM₁₀ were Si, Al, Mg, Ca for 1985, were TC, Si, SO₄2-, Al, Ca for 2001and were TC, Si, SO₄2-, NO₃-, Ca for 2011, respectively. The change of different chemical compositions has taken on in different styles. The proportion of Si in PM₁₀ decreased sharply first then remained slightly stable, from 28.7% for 1985to 7.6% for 2011, the percentage of carbon component in PM₁₀ decreased slightly, from 24.9% in 2001to 17.9% in 2011, while the concentration percentage of secondary particles (SO₄2- and NO₃-) in PM₁₀ remarkably increased from 10.2% in 2001to 18.3% in 2011. The contribution of soot dust to PM₁₀ decreased from 45% in 1985to 22% in 2011, while the contribution of open sources, secondary particles and motor vehicle exhausts apparently increased from 29%, 6% and 3% in 1985to 35%, 16% and 16% in 2011, respectively. Contribution of main sources to ambient particulate matter became more. The type of particle pollution has been changed from soot pollution to mix pollution to complex pollution.