深圳市城区和郊区黑碳气溶胶对比研究

为了解深圳地区黑碳气溶胶（BC）的污染特征，使用深圳市西涌（XC）站点（郊区）和竹子林（ZZL）站点（城区）2014年1月1日~2015年6月30日测得的BC浓度及常规气象资料，对比研究了深圳地区两个不同代表性站点的BC变化特征.结果表明：在观测期间，郊区XC和城区ZZL站点BC小时平均浓度分别为（1.12±0.90），（2.58±2.00）μg/m³，本底浓度分别为（0.27±1.31），（1.07±0.85）μg/m³，气溶胶吸收系数σ_abs分别为（5.87±4.81），（13.47±10.50） Mm^-1，城区站点值均高于郊区站点.两站点BC浓度分布均为对数正态分布，且都呈现干季高、湿季低的季节变化特点.日变化分析表明ZZL站点BC浓度呈现明显的双峰结构，XC站点日变化不明显.通过计算两地的气溶胶波长吸收指数AAE值，发现两地AAE值均接近1，说明两地BC污染主要来源于化石燃料的燃烧.进一步分析可知XC站点西北方向32km处是世界第三大集装箱码头，当西北风达到一定程度时（10~20m/s），码头排放的污染物将严重影响XC站点的BC浓度.后向轨迹聚类分析结果表明，XC站点主要受中远距离输送影响，ZZL站点主要受周边及本地污染源排放影响.

Comparative study on the characteristics of black carbon aerosol in urban and suburban areas of Shenzhen

To better understand the pollution characteristics of black carbon (BC) in Shenzhen, BC and meteorological factors were measured from January 1, 2014 to June 30, 2015 at XC (suburban site) and ZZL (urban site) in Shenzhen. The results showed the average mass concentrations of BC at XC and ZZL sites during the campaign were (1.12±0.90) μg/m³ and (2.58±2.00) μg/m³ respectively. The background concentrations of BC at the two sites were (0.27±1.31) μg/m³ and (1.07±0.85) μg/m³ respectively. The σ_abs at XC site was (5.87±4.81) Mm^-1 while at ZZL site was (13.47±10.50) Mm^-1. It was found that the values at the urban site were much higher than those at the suburban site. The BC concentrations at both sites were following the logarithmic normal distribution with higher concentrations in the dry season than that in the rainy season. A distinct diurnal pattern of BC with two peaks was observed at ZZL site. In contrast, XC site did not show obvious diurnal variations. The Absorption Angstrom Exponent (AAE) can be considered as an indicator of BC mixing state. It was found to be close to 1at both sites, indicating that BC at the two sites were dominated by fossil fuel combustion. Further study suggested high BC concentrations at XC site were usually associated with northwest wind (10~20m/s) when polluted aerosols were transported from the Shenzhen container wharf, which is the world's third largest container terminal. The backward trajectories clusters analysis indicated that BC at XC site was mainly affected by the long-range transport. WhileBC at the ZZL site was affected by the surrounding areas and local emissions.