The indoor-outdoor characteristics of water-soluble ion in PM 2.5 in Tianjin wintertime

摘要

The indoor and outdoor PM~(2.5)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 PM~(2.5)concentration in dormitory and lab are less than 1 in haze days. Indoor PM~(2.5)concentration increases rapidly with outdoor PM~(2.5)concentration increasing in haze days. The filtration factors of the dormitory and lab indicate nearly half of the outdoor PM~(2.5)enters indoor environment. The human activities in dormitory could cause more the formation of PM~(2.5)than those in lab. The concentration of SO~(4)_(2?)is the highest ion in water-soluble ion for outdoor PM~(2.5). The SO~(4)_(2?), NO~(3)_(?), NH~(4)_(+), and Cl_(?)are generated mainly by outdoor sources; however, the Na_(+), Ca_(2+), and Mg_(2+)are generated mainly by indoor sources. The NH~(4)NO~(3), (NH~(4))~(2)SO~(4), and NH~(4)Cl 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 NH~(4)NO~(3), (NH~(4))~(2)SO~(4), and NH~(4)Cl in PM~(2.5)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.