College of Biology and the Environment, Collaborative Innovation Center of Sustainable Forestry in Southern China of Jiangsu Province, Nanjing Forestry University, Nanjing, China.
Environmental Chemistry and Technology Program, University of Wisconsin-Madison, Madison, WI, USA.
Sci Rep. 2016 Sep 16;6:33331. doi: 10.1038/srep33331.
Black carbon (BC) aerosol has been identified as one of key factors responsible for air quality in Beijing. BC emissions abatement could help slow regional climate change while providing benefits for public health. In order to quantify its variations and contribution to air pollution, we systematically studied real-time measurements of equivalent black carbon (eBC) in PM2.5 aerosols at an urban site in Beijing from 2010 to 2014. Equivalent black carbon (eBC) is used instead of black carbon (BC) for data derived from Aethalometer-31 measurement. Equivalent BC concentrations showed significant temporal variations with seasonal mean concentration varying between 2.13 and 5.97 μg m(-3). The highest concentrations of eBC were found during autumn and winter, and the lowest concentrations occurred in spring. We assessed the temporal variations of eBC concentration during haze days versus non-haze days and found significantly lower eBC fractions in PM2.5 on haze days compared to those on non-haze days. Finally, we observed a clear inverse relationship between eBC and wind speed. Our results show that wind disperses PM2.5 more efficiently than eBC; so, secondary aerosols are not formed to the same degree as primary aerosols over the same transport distance during windy conditions.
黑碳（BC）气溶胶已被确定为导致北京空气质量的关键因素之一。减少 BC 排放不仅有助于减缓区域气候变化，还有助于改善公众健康。为了量化其变化及其对空气污染的贡献，我们系统地研究了 2010 年至 2014 年北京城区大气细颗粒物（PM2.5）中等效黑碳（eBC）的实时测量值。等效黑碳（eBC）用于替代源自 Aethalometer-31 测量的数据中的黑碳（BC）。等效 BC 浓度表现出明显的时间变化，季节性平均值在 2.13 到 5.97μg/m³之间变化。eBC 浓度最高出现在秋季和冬季，最低出现在春季。我们评估了雾霾天和非雾霾天 eBC 浓度的时间变化，发现雾霾天 PM2.5 中的 eBC 分数明显低于非雾霾天。最后，我们观察到 eBC 与风速之间存在明显的反比关系。研究结果表明，在大风条件下，PM2.5 的风速比 eBC 分散效率更高；因此，在相同的传输距离内，二次气溶胶的形成程度不如一次气溶胶。
