A Preliminary Study On The Measurement Of PM_2.5 Oxidation Potential In Guangzhou Based On DTT Method

In recent years,the frequent occurrence of haze pollution in China,PM_2.5 has become one of the most concerned air pollutants.As one of the economically developed regions in China,the Pearl River Delta region,along with the rapid development of urbanization,has formed the air complex pollution with regional characteristics and the particle pollution is relatively serious,which has posed a serious threat to people's health.A major cause of adverse health effects of atmospheric particulate matter is the formation of active oxidative species?ROS?in human cells and oxidative stress induced,and therefore oxidative potential can be used to characterize the impact of atmospheric particulate matter on human health.Atmospheric particulate matter can cause the formation of active Oxidative species in human cells,causing Oxidative stress,which is the main cause of adverse health effects.Oxidative potential is commonly used to characterize the impact of atmospheric particulate matter on human health.Dithiothreonol?DTT?method is a recently developed method for the determination of oxidation potential of particulate matter.This study improved the DTT measurement method of particle extraction method and the reaction process,with super atmosphere monitoring station,Jinan university is located in Guangzhou downtown?113.35°E,23.13°N?as the sample point,measured in January 2018,the atmospheric PM_2.5 in Guangzhou in April the oxidation potential of?DTT_m&DTT_v?,combined with the online atmospheric observations,statistical analysis of the different weather conditions,typical pollution weather conditions of oxidation potential and dry wet season change characteristic;Meanwhile,the content of11 kinds of conventional water-soluble ions and 21 kinds of heavy metals in PM_2.5 were determined,and the contribution of heavy metals to the oxidation potential was analyzed.The main conclusions of this paper are as follows:?1?The average DTT_m in January 2018 is 13.47±3.86 pmol min^-1?g^-1,ranging from 8.15 to 24.3;The average DTT_m in April was 14.66±4.49 pmol min^-1?g^-1,ranging from 10.32 to 31.70.The DTT_v average in January was 4.67±1.06 nmol min^-1 m^-3,and the range was 2.41⁶.10.The average DTT_v in April was 4.45±1.02 nmol min^-1 m^-3,and the range was 2.28⁶.19.Atmospheric PM_2.5 in January and April oxidation potential has no obvious difference,the ash haze days(PM_2.5 mass concentration?75?g/m³)oxidation potential?DTT_m?is not the maximum,and higher DTT_v;Rainfall decreases the oxidation potential?DTT_m&DTT_v?.?2?This study found that there was no significant correlation between PM_2.5oxidation potential DTT_m and most online observation parameters;And DTT_v and PM_2.5,OC/EC,the quality of the online data such as the BC concentration has good correlation,DTT_v and PM_2.5 mass concentration exists a good correlation shows that the bigger the particle concentration obvious adverse health effects,but the correlation between height and cannot show causality,while the carbon component itself exists a good correlation between PM_2.5 and,from another aspect of this illustrate the potential of particulate carbon composition oxidation potential contribution no contribution or contribution is very small.?3?The chelating agent EDTA was added to complexate the metals and quinones,and it was found that the oxidation potentials?DTT_m and DTT_v?of the two forms were significantly reduced,in which the PM_2.5 oxidation potentials(DTT_m-OP,pmol min^-1?g^-1)in January and April were reduced by 86.2%and 90.9%respectively.The PM_2.5oxidation potential(DTT_v-OP,nmol min^-1 m^-3)in January and April decreased by 84.4%and 90.0%respectively.?4?Using parameterized method to quantify the heavy metal elements in Guangzhou PM_2.5's contribution to the oxidation potential,found that heavy metals especially Cu???and Mn???is a major contributor,oxidation potential of the metal source analysis,we preliminary judgment traffic pollution,industrial emissions,especially metal smelting is likely to be the main source of oxidation potential contribution.