南昌市土壤风沙尘PM2.5中水溶性离子分布特征及来源初探

为了解南昌市土壤风沙尘PM_(2.5)中水溶性离子的分布特征,利用颗粒物再悬浮采样器采集土壤风沙尘的PM_(2.5)样品,并采用离子色谱仪分析了9种水溶性离子的含量。结果表明,土壤风沙尘PM_(2.5)中9种水溶性离子的含量之和为11. 126±2. 703 mg/g,阳离子中平均含量最高的是Ca~(2+)(1. 684±0. 545 mg/g),阴离子中最高的是SO_4~(2-)(3. 568±1. 553 mg/g)。SO_4~(2-)、NO_3~-、Ca~(2+)和Cl~-是土壤尘PM_(2.5)中的主要离子组成,占总离子浓度的80. 60%。与其他城市对比,南昌市土壤风沙尘PM_(2.5)中离子基本处于较低水平。阴阳离子当量浓度比值为1. 26,表明土壤风沙尘的PM_(2.5)颗粒为弱酸性。空间插值分析表明南昌市西南部土壤尘PM_(2.5)中的离子含量分布相对较高,而东部及北部多处于较低水平。相关性分析表明Na~+、F~-和NH_4~+具有同源性,K~+与其他离子都不相关。NO_3~-/SO_4~(2-)的比值介于0. 26～0. 97间,整体上反映出固定源对土壤风沙尘PM_(2.5)的影响更显著。

Distribution Characteristics of Water-soluble Ions in PM2.5 Fraction of Soil Dust in Nanchang City

In order to understand the characteristics in PM_2.5 fraction of soil dust in Nanchang city, PM_2.5 samples in soil dusts were collected by a resuspension sampler, then the contents of nine water-soluble inorganic ions were detected by ion chromatography. The results showed that the content of total water-soluble ions was 11.126±2.703 mg/g. SO₄^2- showed the highest content (3.568±1.553 mg/g) in anions and Ca²⁺ showed the highest content(1.684±0.545 mg/g) in cations. SO₄^2-, NO₃^-, Ca²⁺ and Cl^- were the main water-soluble ions in PM_2.5 of soil dust, accounting for 80.60% of total water-soluble ions. Compared with other cities, the level of water-soluble ions in PM_2.5 of soil dust in Nanchang was lower. The ratio of equivalent concentrations of cations to anions was 1.26, suggesting that PM_2.5 of soil dust was slightly acidic. Spatial interpolation analysis showed that the contents of water-soluble ions in the southwest of Nanchang city were relatively higher, while most of the eastern and northern parts were at a lower level. The correlation analysis showed that Na⁺, F^-, NH₄⁺ had homology while K⁺ was not related to other ions. The ratios of NO₃^-/SO₄^2-were from 0.26 to 0.97, indicating that the effects of fixed sources on the soil dust PM_2.5 were more significant.