东海PM2.5和PM10中水溶性离子的组成与化学特性

2014年5~6月在东海海域采集PM_2.5和PM₁₀气溶胶样品，通过离子色谱法对样品中主要水溶性阳离子（Na⁺、K⁺、NH₄⁺、Mg²⁺、Ca²⁺）和阴离子（Cl^-、NO₃^-、SO₄^2-、MSA）的浓度进行测定，并结合相关数理统计方法探讨了其主要来源.结果表明，PM_2.5和PM₁₀样品中主要水溶性离子的总浓度范围分别为7.9~23.7μg/m³和10.4~47.9μg/m³，平均值分别为（14.9±5.8）μg/m³和（21.3±10.7）μg/m³.二次离子（nss-SO₄^2-、NO₃^-和NH₄⁺）浓度最高，分别占测定离子总浓度的80.8%和73.3%，其中SO₄^2-和NH₄⁺主要富集在细颗粒物（PM_2.5）中，NO₃^-主要富集在粗颗粒物（PM₁₀）中.富集因子及相关性分析表明K⁺主要来自陆源，Mg²⁺受海源和陆源双重输入影响.阴阳离子浓度平衡计算结果表明，细颗粒物样品呈弱碱性；粗颗粒物样品酸碱基本中和.两种样品中NH₄⁺的主要结合方式均为（NH₄）₂SO₄和NH₄NO₃.来源分析结果表明，PM_2.5和PM₁₀样品中生源硫化物对nss-SO₄^2-的贡献率分别为13.7%和8.7%.根据估算的干沉降通量结果，NH₄⁺对氮沉降的贡献程度小于NO₃^-.

Distributions and chemical characteristics of water soluble ions in PM2.5 and PM10 over the East China Sea

The PM_2.5 and PM₁₀ samples were collected over the East China Sea in May and June,2014.The main water-soluble cations (Na⁺,K⁺,NH₄⁺,Mg²⁺ and Ca²⁺) and anions (Cl^-,NO₃^-,SO₄^2- and MSA) were determined by ion chromatography method,meanwhile the main sources of these ions were discussed by a series of mathematical statistics methods.The concentrations of the total water-soluble ions ranged from 7.9 to 23.7 μg/m³ in PM_2.5 and from 10.4 to 47.9 μg/m³ in PM₁₀,respectively,with the average values of (14.9±5.8)μg/m³ and (21.3±10.7)μg/m³.The results showed that the level of the secondary ions (nss-SO₄^2-,NO₃^- and NH₄⁺) were the highest,accounting for 80.8% and 73.3% of total identified ions in PM_2.5 and PM₁₀.SO₄^2- and NH₄⁺ were mainly found in the fine particles (PM_2.5),while NO₃^- mainly was found in the coarse particles (PM₁₀).Enrichment factors and correlation analysis showed that K⁺ mainly came from crust and the source of Mg²⁺ was under the double influence of crust and ocean.The calculated results of equivalent concentrations of anions and cations showed that acid and alkaline compositions were not neutralized completely with weak alkalinity in PM_2.5,while those were neutralized completely in PM₁₀.NH₄⁺ was mainly in the forms of (NH₄)₂SO₄ and NH₄NO₃ both in two particles.The analysis of sulfate source showed that contributions of biogenic sulfates to nss-SO₄^2- were 13.7% and 8.7% in PM_2.5 and PM₁₀.In addition,accounting to the calculation of dry deposition,the contribution of NH₄⁺ to the nitrogen deposition were obvious less than that of NO₃^-.