鹤山气溶胶光学性质和单颗粒化学组分的研究

2014年10~11月在广东省鹤山大气超级站利用单颗粒气溶胶质谱仪（SPAMS）、积分式浊度仪和黑碳仪在线观测了单颗粒气溶胶的化学组成与气溶胶光学特征.采用Art-2a分类法将单颗粒分为9类：有机碳-硫酸盐/硝酸盐颗粒（OC-Sulfate/Nitrate）、元素碳-硫酸盐/硝酸盐颗粒（EC-Sulfate/Nitrate）、元素碳有机碳-硫酸盐/硝酸盐颗粒（ECOC-Sulfate/Nitrate）、高分子有机碳颗粒（HOC）、海盐颗粒（Sea-salt）、硅酸盐颗粒（Si-rich）、左旋葡聚糖颗粒（Lev）、钾-硫酸盐/硝酸盐颗粒（K-Sulfate/Nitrate）、金属颗粒（Metal）.从清洁期到灰霾期气溶胶的吸收系数、散射系数和单次散射反照率（SSA）显著升高，气溶胶消光能力增强，同时EC-Sulfate/Nitrate颗粒占比从34.8%降至31%，OC-Sulfate/Nitrate颗粒从9.9%增加至23.6%，K-Sulfate/Nitrate二次颗粒从8.5%增加至14%，且灰霾期OC-Sulfate/Nitrate颗粒与硫酸盐、硝酸盐和铵盐的混合程度增强，因此老化的OC-Sulfate/Nitrate颗粒和二次组分颗粒对气溶胶消光系数的增加有重要贡献.在大气相对湿度从50%增加到70%以上的过程中，气溶胶散射系数和吸收系数升高，消光系数由326.1Mm^-1增加到362.9Mm^-1，SSA有所下降，PM_2.5质量消光效率由4.98增加到5.99，EC-Sulfate/Nitrate颗粒和K-Sulfate/Nitrate二次颗粒占比下降，而OC-Sulfate/Nitrate颗粒的占比由7.79%增加到14.29%，且OC-Sulfate/Nitrate颗粒中富含硫酸盐、硝酸盐和铵盐，表明高相对湿度下老化的OC-Sulfate/Nitrate颗粒数目增多对气溶胶消光系数的增强有重要影响.

The aerosol optical characteristics and chemical composition of single particles in Heshan

The chemical composition and optical characteristics of single particle aerosols were observed using a single particle aerosol mass spectrometer (SPAMS), nephelometer and aethalometer at the Heshan Atmospheric Supersite in Guangdong from October to November in 2014. Single particles were classified into 9classes by Art-2a classification method including organic carbon-sulfate/nitrate particles (OC-Sulfate/Nitrate), elemental carbon-sulfate/nitrate particles (EC-Sulfate/Nitrate), elemental and organic carbon-sulfate/nitrate particles (ECOC-Sulfate/Nitrate), high molecular organic carbon particles (HOC), sea salt particles (Sea-salt), silicate particles (Si-rich), levoglucosan particles (Lev), potassium-sulfate/nitrate particles (K-Sulfate/Nitrate) and metal particles (Metal). The absorption coefficient, scattering coefficient and single scattering albedo (SSA) of the aerosols significantly increased from clean to haze periods. The aerosol extinction ability enhanced along with the percentage of EC-Sulfate/Nitrate particles decreased from 34.8% to 31%, and OC-Sulfate/Nitrate particles increased from 9.9% to 23.6% as well as K-Sulfate/Nitrate particles increased from 8.5% to 14%. Besides, the OC-Sulfate/Nitrate particles were internally mixing with sulfate, nitrate and ammonium in the haze period, suggesting the aged OC-Sulfate/Nitrate particles and K-Sulfate/Nitrate particles had a large contribution to the increase of aerosol extinction coefficient. The aerosol scattering coefficient and absorption coefficient enhanced as the increase of RH from 50% to above 70%, and the extinction coefficient increased from 326.1Mm^-1 to 362.9Mm^-1, while the SSA decreased. The PM_2.5 mass extinction efficiency increased from 4.98 to 5.99, and the percentage of EC-Sulfate/Nitrate and K-Sulfate/Nitrate particles decreased, while the proportion of OC-Sulfate/Nitrate particles increased from 7.79% to 14.29%, indicating the increase of aged OC-Sulfate/Nitrate particles mixing with sulfate, nitrate and ammonium salts has an important impact on the enhancement of the aerosol extinction coefficient under high RH conditions.