民用燃煤排放细颗粒中金属元素排放特征及单颗粒分析

Emission characteristics and individual particle analysis of metals in fine particles emitted from residential coal burning

通过模拟民用煤炭燃烧,采集了5种不同成熟度的典型块煤燃烧排放的单颗粒和PM_(2.5)样品.利用带能谱仪的透射电镜研究了金属颗粒的单颗粒特征,运用电感耦合等离子体质谱仪和发射光谱仪获得了PM_(2.5)样品中14种金属元素(包括8种重金属)的浓度特征.结果显示,民用燃煤排放的含金属元素的颗粒物主要有矿物颗粒、部分碳质颗粒、富K颗粒、富S[K]颗粒、富Fe颗粒、富Zn颗粒和富Pb颗粒共7种.5种民用燃煤排放的14种金属元素占PM_(2.5)的1.29%～15.54%,其中Al、Ca和Na占金属元素总量的57%～80%,是民用燃煤排放的主要的金属元素;V、Cr、Mn、Co、Ni、Cu、Zn和Pb这8种重金属元素占PM_(2.5)的0.09%～2.53%,其中Zn和Pb占重金属总量的54%～91%,在民用燃煤排放的重金属中占主导.单颗粒分析结果显示Zn和Pb元素主要富集在粒径小于1μm的富Zn和富Pb颗粒中,这些细颗粒能够直接进入人体,对人体健康造成威胁.因此,建议居民应通过使用精煤或天然气等清洁能源来减少重金属的排放.

Five typical coals with different maturities were selected and burned in the residential stove,and then the individual particles and PM2.5 samples from these coals burning were collected.A transmission electron microscopy with energy-dispersive X-ray spectrometry(TEM-EDS)was used to analyze physicochemical characteristics of metal-containing individual particles.The concentrations of 14metals(including eight heavy metals)in PM2.5 were detected by inductively coupled plasma mass spectrometry and inductively coupled plasma optical emission spectrometer.The individual particle analysis showed seven different types of metal-containing particles:mineral,K-rich,S[K]-rich,Fe-rich,Zn-rich,and Pb-rich particles,and some carbonaceous particles.Mass concentrations of 14metals and eight heavy metals accounted for 1.29%~15.54%and 0.09%~2.53%in PM2.5,respectively.Al,Ca and Na were the dominant metals,accounting for 57%~80%of total metals.Zn and Pb were the dominant heavy metals,accounting for 54%~91%of total heavy metals.TEM observations showed that Zn and Pb mainly occurred in Zn-rich and Pb-rich particles with size<1μm,respectively.These heavy metals can be breathed into deep of human lung and pose adverse effects on human health.Therefore,in order to protect human health,we suggest that residents should use clean coal or clean energy to reduce the heavy metals emissions.