南京江北新区PM_(2.5)中水溶性离子的季节特征和来源解析

Seasonal characteristics and source apportionment of water-soluble ions in PM_(2.5) of Nanjing Jiangbei New Area

为探究南京江北新区PM_(2.5)中水溶性离子的季节特征和来源,于2019年共采集了113个有效PM_(2.5)样品.用称重法和离子色谱法分别测定出PM_(2.5)和10种水溶性离子的质量浓度,并使用PMF源解析法对其进行来源解析.结果表明,观测期间南京江北新区PM_(2.5)和水溶性离子年平均浓度分别为(78.34±29.64)和(35.68±18.30)μg·m^(-3),其四季变化趋势相同,冬季浓度高,夏季浓度低.10种水溶性离子中NO^(-)_(3)、SO_(4)^(2-)和NH^(+)_(4)的浓度远远高于其他离子,其在总离子中的含量高达89.9%.南京江北新区四季PM_(2.5)中NH^(+)_(4)主要与HSO-4和NO^(-)_(3)结合存在.硫氧化率(SOR)和氮氧化率(NOR)的年均值分别为0.53和0.28,说明观测期间大气中氮硫的二次生成率较高.南京江北新区PM_(2.5)中水溶性离子主要来源为二次转化、海盐和扬尘.

To investigate seasonal variations and source of water-soluble ions in Nanjing Jiangbei New Area, a total of 113 PM_(2.5) samples were collected in 2019. Water-soluble inorganic ions were determined by ion chromatography, and PMF source analysis was employed for source apportionment. The result showed that the annual average concentration of PM_(2.5) and water-soluble ions in Nanjing Jiangbei New Area were(78.34±29.64) and(35.68±18.30) μg·m^(-3), respectively. The variation trend of the four seasons was similar with higher concentration in winter and lower concentration in summer. Concentrations of NO^(-)_(3),SO_(4)^(2-), and NH^(+)_(4) in 10 ions were much higher than others, and the relative contribution of total ions concentrations was up to 89.9%. NH^(+)_(4) mainly combined with HSO-4 and NO^(-)_(3) of four seasons in Nanjing Jiangbei New Area. The mean values of the sulfur oxidation rate(SOR) and the nitrogen oxidation rate(NOR) were 0.53 and 0.28, respectively, indicating that there was a high secondary aerosol transformation rate of nitrogen and sulfur. The water-soluble ions of PM_(2.5) mainly derived from secondary transformation, sea salt and dust in Nanjing Jiangbei New Area.