State Environmental Protection Key Laboratory of Urban Ambient Air Particulate Matter Pollution Prevention and Control & Center for Urban Transport Emission Research, College of Environmental Science and Engineering, Nankai University, Tianjin, 300350, China.
State Environmental Protection Key Laboratory of Urban Ambient Air Particulate Matter Pollution Prevention and Control & Center for Urban Transport Emission Research, College of Environmental Science and Engineering, Nankai University, Tianjin, 300350, China.
Environ Pollut. 2018 Sep;240:155-166. doi: 10.1016/j.envpol.2018.04.111. Epub 2018 May 4.
In Xi'an, a city that frequently experiences serious PM pollution in northern China, 1476 PM and 1464 PM valid daily filter samples were collected at six sites from December 2014 to November 2015 and analyzed for 29 species. The annual mean PM and PM concentrations were 149.4 ± 93.1, 108.0 ± 70.9 μg/m, respectively. Organic carbon (OC) is the predominant PM component while crustal material predominated in PM. Sulfate concentrations, which was the largest component in Xi'an PM in previous studies, were lower than nitrate. Winter sulfate, OC, and elemental carbon (EC) have decreased since 2003, while nitrate remained constant in recent years and the ratio of NO/SO increased from 0.4 in 2006 to 1.3 in 2014. This result suggests that the motor vehicle contribution to PM has increased relative to coal-fired power plant emissions over the past decade. The mass fractions of crustal material, sulfate, and EC in PM decreased as the PM concentrations increased from "clean" days (<50 μg/m) to the highest values, while nitrate significantly increased. Despite forming through secondary reactions, the high concentrations of SOC and SO in winter are attributed to primary emissions and particularly to residential heating and cooking with coal. Primary SOC and SO accounted for 33% and 42% of their total PM concentrations in winter, respectively. Therefore, control measures applied to these primary sources can substantially improve air quality.
在中国北方经常遭遇严重 PM 污染的西安市，2014 年 12 月至 2015 年 11 月在六个地点采集了 1476 个有效日滤膜样本和 1464 个有效日滤膜样本，共分析了 29 种物种。年平均 PM 和 PM 浓度分别为 149.4±93.1μg/m 和 108.0±70.9μg/m。有机碳（OC）是 PM 的主要成分，而地壳物质则在 PM 中占主导地位。硫酸盐浓度在以前的研究中是西安 PM 的最大组成部分，但低于硝酸盐。自 2003 年以来，冬季硫酸盐、OC 和元素碳（EC）的浓度有所下降，而近年来硝酸盐保持不变，NO/SO 的比值从 2006 年的 0.4 增加到 2014 年的 1.3。这一结果表明，在过去十年中，机动车对 PM 的贡献相对于燃煤电厂的排放有所增加。随着 PM 浓度从“清洁”日（<50μg/m）到最高值的增加，PM 中地壳物质、硫酸盐和 EC 的质量分数降低，而硝酸盐显著增加。尽管 SOC 和 SO 是通过二次反应形成的，但冬季高浓度的 SOC 和 SO 归因于一次排放，尤其是煤炭的居民供暖和烹饪。在冬季，SOC 和 SO 的一次排放分别占其总 PM 浓度的 33%和 42%。因此，针对这些一次排放源采取的控制措施可以显著改善空气质量。
