Department of Environment and Energy Engineering, Chonnam National University, 77 Yongbong-Ro, Buk-gu, Gwangju 500-757, Korea.
Environ Sci Process Impacts. 2015 Oct;17(10):1794-805. doi: 10.1039/c5em00225g. Epub 2015 Sep 7.
Continuous measurements of black carbon (BC) concentrations in PM2.5 were conducted using a single-wavelength aethalometer (@880 nm, Magee Sci., AE16) at a site close to a roadway (∼70 m from roadside) in Gwangju, Korea, during winter (December-February) to investigate the characteristics and sources of BC particles. The BC concentrations ranked in the order of January > December > February, probably due to lower boundary layer height, ambient temperature, and wind speed during January. Diurnal patterns in BC and carbon monoxide (CO) levels exhibited peak concentrations during the morning and evening hours coinciding with rush-hour traffic, with a strong correlation (R(2)) ranging from 0.52 (December) to 0.87 (January). It was found that wind speed was an important factor controlling BC concentrations at the site. Very high BC concentrations, up to ∼18.0 μg m(-3), were observed at wind speeds < 1.5 m s(-1). The BC concentrations acquired under weak wind conditions are highly correlated with CO with ΔBC/ΔCO (the slope of BC and CO correlation) of 0.0063 (R(2) = 0.55, p < 0.01) and 0.0065 (R(2) = 0.59, p < 0.01) μg m(-3) ppbv(-1) during day and night, respectively, suggesting no significant difference in the fraction of diesel vehicles between the daytime and nighttime periods. Two BC episodes, "A" and "B", were classified based on BC, PM2.5, and secondary SO4(2-) concentrations, and discussed to investigate the difference in the evolution of the BC observed. Episode "A" was associated with high BC and low PM2.5 and SO4(2-) concentrations, while episode "B" was associated with high concentrations of BC, PM2.5, and SO4(2-). Based on the temporal profiles of BC, NO, and NOx concentrations, CO/NOx ratio, and potential source contribution function map for BC, the BC observed during episode "A" was mostly attributed to locally produced emissions (e.g., traffic). However, the BC during episode "B" was influenced by long-range transport of air masses from China, as well as the local emissions.
在中国广州，冬季（12 月至 2 月）期间，在靠近车道的位置（距路边约 70 米）使用单波长黑碳（BC）光度计（@880nm，Magee Sci.，AE16）对 PM2.5 中的 BC 浓度进行了连续测量，以调查 BC 颗粒的特征和来源。BC 浓度的顺序为 1 月>12 月>2 月，这可能是由于 1 月的边界层高度、环境温度和风速较低所致。BC 和一氧化碳（CO）水平的日变化模式在早高峰和晚高峰交通时段表现出峰值浓度，与交通高峰时段一致，相关性（R(2)）范围为 0.52（12 月）至 0.87（1 月）。研究发现，风速是控制该地点 BC 浓度的重要因素。在风速<1.5m/s 时，观测到高达约 18.0μg/m(-3)的极高 BC 浓度。在弱风条件下获得的 BC 浓度与 CO 高度相关，BC 与 CO 的相关性（BC 和 CO 相关性的斜率）为 0.0063（R(2)=0.55，p<0.01）和 0.0065（R(2)=0.59，p<0.01）μg/m(-3)ppbv(-1)，分别在白天和夜间，表明白天和夜间柴油车的比例没有明显差异。根据 BC、PM2.5 和二次 SO4(2-)浓度，将两个 BC 事件“A”和“B”分类，并讨论了它们对观察到的 BC 演化的差异。事件“A”与高 BC 和低 PM2.5 和 SO4(2-)浓度有关，而事件“B”与高浓度的 BC、PM2.5 和 SO4(2-)有关。根据 BC、NO 和 NOx 浓度、CO/NOx 比以及 BC 的潜在源贡献函数图的时间分布，事件“A”期间观测到的 BC 主要归因于本地排放（例如交通）。然而，事件“B”期间的 BC 受到来自中国的空气团长距离传输以及本地排放的影响。
