| In recent years, with frequently occurred haze weather, atmospheric fine particles PM2.5 receive widespread attention, Especially with the introduction of the comprehensive prevention and control of heavy metal pollution in 12th Five-Year, the relevant detection and analysis has been carried out. Metal elements in atmospheric particulate matter detection, at home and abroad coexist atomic absorption spectrometry (AAS), inductively coupled plasma atomic emission spectrometry (ICP-AES), inductively coupled plasma mass spectrometry (ICP-MS), X-ray fluorescence spectrometry method, neutron activation analysis and proton-induced X-ray spectroscopy detection method, of which the most widely used method in China is AAS, ICP-AES and XRA. The ICP-MS method can achieve multi elements analysis, with high sensitivity, low detection limit, less sampling amount, etc., it can detect of most elements in the periodic table, determination and analysis of concentration as low as nanograms per liter (ng/L) or parts per trillion (PPT), has more advantages in analysis of trace and ultra trace heavy metals in atmospheric fine particulate matter PM2.5In the sample pretreatment, high pressure sealed digestion and microwave digestion method heat the sample fast and can reach high temperature, with high heating digestion ability, can greatly reduce the sample dissolution time. Less solvent consumption, low blank, to avoid the volatilization loss and sample contamination, improve the analysis accuracy and precision, and reduce the work intensity, improve the working environment. Especially microwave digestion method with its safe, efficient and easy to operate, has become the main digestion method of heavy metal samples.This study use microwave digestion, and inductively coupled plasma mass spectrometry (ICP-MS) to determine 10 heavy metal elements in the atmosphere PM2.5 of Tai’an city:Al, Fe, Zn, Pb, Mn, As, Cu, Cr, Ni, Cd, through the experimental comparison of different acids systems and their dosage, different microwave transmission power conditions, select the optimum digestion conditions, solve the microwave digestion process of "paste pot" issue due to organic membrane becomes sticky, to explore an efficient, accurate, convenient and reliable method for the detection of heavy metals in airborne fine particulate matter,and the atmospheric PM2.5 in Tai’an city were sampled and analyzed, a preliminary analysis of the source, and put forward the countermeasures and suggestions.The main conclusions are as follows:1. In the digestion of PM2.5 samples collected by polypropylene filte, HNO3 (soaked overnight) and H2O2 digestion system with a low cost, high accuracy, high precision, easy to operate, low pollution features, compared to the other three. More suitable for fast, efficient and accurate analysis of the total heavy metal content in large quantities of samples.2. The concentrations of Fe and Al in PM2.5 of Tai’an City were significantly higher than other elements, in which Al element is mainly from natural sources, Fe element due to the dual effects of natural and anthropogenic sources, the overall value is greater than Al element, the other elements are pollution elements, mainly from anthropogenic sources, its concentration gradient order of Fe> Al> Zn> Pb> Mn> as> Cu> Cr> Ni> Cd (annual mean of three sampling points).Anthropogenic pollution elements Zn and Pb concentration is the highest in PM2.5 of Tai’an city which are the major elements of heavy metal pollution, the concentration of Zn in heating season rise to the two more than Al, indicating that coal combustion and vehicle pollution is serious3. The concentration of heavy metals in PM2.5 of Taian City showed obvious seasonal characteristics:high during wind blown season and heating season, low before heating season,the rainy season is the lowest, indicating the wind blown season and heating season is the main period of heavy metal pollution in PM2.5 in Taian city. The highest concentration level of wind blown season was Al, followed by Fe, Zn, Pb, As, Cu, Mn, Cr, Ni, Cd; the highest concentration of heating season is Fe elements, followed by Zn, Al, Pb, Cu, Mn, As, Cr, Ni, Cd, The influence of the dust source in the wind blown season was remarkable, and in the heating season was significantly affected by the burning of coal and motor vehicles.4. The concentration of heavy metals in the PM2.5 of the monitoring points in Tai’an city was significantly affected by the surrounding environment functional area. Overall average industrial zone> Business mixing area> Residential area >Tourist Area. Especially in the heating season, the air flow is stable, less external sources of interference, frequent fog and haze, the regional pollutant accumulation, showing a significant regional pollution characteristics.5. Coal dust (coal-fired power plants, industrial boilers and civilian burning, etc.) is the primary source of atmospheric PM2.5 in Tai’an City, followed by motor vehicle dust and road dust, the management of coal dust and motor vehicles should be focus on and strengthened. |
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