Intercomparison of PM_(2.5) concentration measured by gravimetric measurement method and automated monitoring method

PM2.5concentration was monitored in 6cities in Zhejiang Province,Jinhua,Quzhou,Wenzhou,Lishui,Ningbo and Hangzhou,using gravimetric measurement method and automated monitoring method in 2013.The collected data was analyzed and estimated by two indexes of correlation and relative deviation.The results were as follows:(1)Correlation analysis indicated that there was good relativity between gravimetric measurement method and automated monitoring method in 6cities.The correlation efficients were all higher than 0.95 and the intercepts were all in the range of-0.010-0.010 mg/m3,but the slopes varied.The slope was higher than 0.90 in Quzhou and Lishui,in the range of 0.85-0.90 in Jinhua,Wenzhou and Hangzhou,lower than 0.80 in Ningbo.(2)The results of relative deviation analysis showed that the relative deviation between gravimetric measurement method and automated monitoring method in 6cities was in the range of-34.2%-36.5%.The relative deviation data in the range of±15%and the negative values accounted for 82.6% and 80.0% of the total samples,respectively.(3)The divergence between PM2.5gravimetric measurement method and automated monitoring method was related to regional condition,season and PM2.5concentrations.The annual average of absolute relative deviation(︱RD︱)between gravimetric measurement method and automated monitoring method in different cities exhibited an order of QuzhouLishuiJinhuaNingbo WenzhouHangzhou.Generally speaking,the average of absolute relative deviation in spring was higher than that in summer,while in autumn it was higher than that in winter.The average of absolute relative deviation between gravimetric measurement method and automated monitoring method was the lowest under the high-concentration(ρ10.150mg/m3),the highest under the middle-concentration(0.050≤ρ1≤0.150mg/m3).The average of absolute relative deviation under the low-concentration(ρ10.050mg/m3)was between that of the high-concentration and middle-concentration.