兰州市PM_(2.5)中重金属元素的来源及健康风险评价

Sources and Health Risk Assessment of Heavy Metals in PM_(2.5)in Lanzhou City

文章于非采暖期(2022年6月1日-8月31日)和采暖期(2022年11月1日-2023年1月31日)在兰州市城关区采集了121个PM_(2.5)样品,并对其中14种重金属元素的污染特征、来源及健康风险进行了研究。结果表明,兰州市采暖期的PM_(2.5)平均浓度((44.1±12.2)μg/m^(3))约为非采暖期PM_(2.5)平均浓度((20.8±3.05)μg/m^(3))的2倍,PM_(2.5)中14种重金属元素的平均浓度在采暖期((4 443±953) ng/m^(3))远高于非采暖期((2 854±426) ng/m^(3)),其中Al、Ca、Fe、Cu和K是兰州市PM_(2.5)中主要的重金属元素。富集因子分析结果表明,受人为活动影响较大的Zn、Se、Cd和Cu在采暖期的EFs值要远远大于非采暖期。正定矩因子分析的结果显示兰州市PM_(2.5)中14种重金属元素主要来源于土壤扬尘、生物质燃烧和工业生产混合排放(39.1%),其次为工业排放(23.3%)、交通排放(20.2%)和燃煤排放(17.4%)。健康风险评价结果显示,所有致癌元素中Cr的致癌风险最高,且在非采暖期和采暖期对成年男性、成年女性和儿童均存在致癌风险,Mn在采暖期对成年男性、成年女性和儿童均存在非致癌风险。因此,兰州市PM_(2.5)中的Cr和Mn的排放需要引起相关部门的高度关注,对于产生这2种元素的煤炭燃烧排放和电镀、冶金、制革和建筑施工等工业生产应该采取一定的措施进行减排监管。总致癌风险和总非致癌风险呈现儿童>成年男性>成年女性的特点。

A total of 121 PM_(2.5)samples were collected in Chengguan District of Lanzhou during non-heating period(June 1,2022-August 31,2022)and heating period(November 1,2022-January 31,2023),and the pollution characteristics,sources and health risks of 14 elements were investigated.The results showed that the average PM_(2.5)concentration((44.1±12.2)μg/m^(3))in the heating period was about twice that in the non-heating period((20.8±3.05)μg/m^(3)).The average concentration of 14 elements in PM_(2.5)in heating period((4443±953)ng/m^(3))was much higher than that in non-heating period((2854±426)ng/m^(3)),among which Al,Ca,Fe,Cu and K were the main elements in PM_(2.5)in Lanzhou City.The results of enrichment factor analysis and positive matrix factorization showed that 14 heavy metal elements in PM_(2.5)were mainly from the mixed sources(soil dust,biomass combustion and industrial emissions)(39.1%),followed by industrial emissions(23.3%),traffic emissions(20.2%)and coal combustion emissions(17.4%).Health risk assessment results showed that Cr had the highest carcinogenic risk among all carcinogenic elements,and there were carcinogenic risks for adult males,adult females and children in non-heating period and heating period.Mn had non-carcinogenic risks for adult males,adult females and children in heating period.Therefore,the emission of Cr and Mn in PM_(2.5)needs to arouse the high attention of relevant departments,and certain measures should be taken for emission reduction supervision of coal combustion and industrial production such as electroplating,metallurgy,tanning and building construction that produce these two elements.The total carcinogenic risk and total non-carcinogenic risk were in the order of children>adult males>adult females.