Chemical Speciation of Heavy Metals in PM2.5 and Optimization of Extraction Conditions in Spring and Winter in Chengdu

In order to study the speciation distribution of heavy metals in air solid particles more accurately and effectively, the chemical speciation of copper, lead, manganese, cadmium and chromium was extracted by mixed acid sealed digestion method and improved Fernndez method. The total content of copper, lead, manganese, cadmium and chromium in samples was determined by ICP-MS. The results showed that the total amount of copper, lead, cadmium, chromium and manganese in soil standard samples was within the certified value of soil component analysis reference materials and the recovery rate was above 90 %. In winter and spring, the recovery rate of copper in all samples ranged from 80.23 to 97.92 %. The recovery rate of lead ranged from 83.77 to 98.40 %. The recovery rate of manganese ranged from 82.07 to 99.97 %. The recoveries of cadmium and chromium are 81.84 %～99.72 % and 88.96-99.16 %, respectively. These data show that the method has the characteristics of low detection limit, high precision and good accuracy. The main forms of copper, lead, manganese, cadmium and chromium in PM2.5 in northeastern Chengdu are soluble and reducible, accounting for more than 75 % of all forms. Among them, copper, cadmium and manganese are mainly soluble, while lead and chromium are mainly reducible. There is a significant positive correlation between the total amount and form of copper, lead, manganese, cadmium and chromium. Relevance.