The indoor-outdoor characteristics of water-soluble ion in PM2.5 in Tianjin wintertime
2018
Wang, Baoqing | Niu, Honghong | Liu, Bowei | Hu, Xinxin | Ren, Zihui
The indoor and outdoor PM₂.₅ mass concentration, water-soluble ion by filter sampler was analyzed on December 3–21, 2015 during wintertime in Tianjin, China. The results indicate that high humidity conditions result in the accumulation of atmospheric pollutants and reduce atmosphere visibility. The I/O ratio for PM₂.₅ concentration in dormitory and lab are less than 1 in haze days. Indoor PM₂.₅ concentration increases rapidly with outdoor PM₂.₅ concentration increasing in haze days. The filtration factors of the dormitory and lab indicate nearly half of the outdoor PM₂.₅ enters indoor environment. The human activities in dormitory could cause more the formation of PM₂.₅ than those in lab. The concentration of SO₄²⁻ is the highest ion in water-soluble ion for outdoor PM₂.₅. The SO₄²⁻, NO₃⁻, NH₄⁺, and Cl⁻ are generated mainly by outdoor sources; however, the Na⁺, Ca²⁺, and Mg²⁺ are generated mainly by indoor sources. The NH₄NO₃, (NH₄)₂SO₄, and NH₄Cl accounts for 20.2~41.8%, 32.0~51.4%, and 6.4~10.6% of the total water-soluble ion in different indoor-outdoor environment. The total secondary aerosols including NH₄NO₃, (NH₄)₂SO₄, and NH₄Cl in PM₂.₅ are 28.3, 42.1, 28.2, 31.0, and 33.9% in outdoor environment for haze days, outdoor environment for non-haze days, dormitory for haze days, dormitory for non-haze days, and lab for haze days, respectively.
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