承德市PM_(2.5)中多环芳烃的季节分布特征、来源解析及健康风险评价

Seasonal Distribution Characteristics,Source Analysis,and Health Risk Evaluation of PAHs in PM_(2.5) in Chengde

为研究承德市PM_(2.5)中多环芳烃(PAHs)的季度变化特征和污染来源,于2019年的1、4、7和10月采集PM_(2.5)样品,采用气相色谱-质谱联用仪(GC-MS)测定了16种PAHs的浓度,并利用时序变动、特征比值和正定矩阵因子模型(PMF)的方法,分析了各季节PAHs的浓度变动、组分特征和潜在污染源.此外,为评价PAHs对健康风险的影响,采用BaP毒性当量法(BaP_(Teq))及增量终生致癌风险(ILCR)模型,并结合PAHs数据和PMF结果进行分析.结果表明,采样期间承德市PM_(2.5)中ρ(ΣPAHs)的变化范围为2.7~246.4 ng·m^(-3),呈现(136.8±52.1)ng·m^(-3)(冬季)>(70.3±36.7)ng·m^(-3)(秋季)>(24.7±17.4)ng·m^(-3)(春季)>(13.7±9.4)ng·m^(-3)(夏季)的显著季节特征.不同环数PAHs的浓度占总浓度的占比中,5~6环的PAHs是4个季节的主要成分,2~3环的占比较少,4环在冬季的占比最高(37.63%).春季和夏季原油和石油挥发泄漏排放对PAHs的贡献率相对较高,秋季和冬季燃煤和生物质燃烧排放源占绝对优势;BaP_(Teq)表现为:冬季>秋季>春季>夏季;ILCR模型指出,成人的呼吸暴露风险高于儿童,成人在春季、秋季和冬季存在不同程度的致癌风险,儿童仅在冬季存在一定程度的致癌风险,成人和儿童ILCR在4个季节的变化均为:冬季>秋季>春季>夏季.

In order to study the seasonal variation characteristics and pollution sources of polycyclic aromatic hydrocarbons(PAHs)in PM_(2.5) in Chengde,PM_(2.5) samples were collected in January,April,July,and October 2019,and the concentrations of 16 PAHs were determined using gas chromatography-mass spectrometry(GC-MS).In addition,the health risks of PAHs were evaluated by using the BaP toxicity equivalent method(BaP_(Teq))and incremental lifetime carcinogenic risk(ILCR)model based on PAHs and PMF results.The results showed that the variation inρ(PAHs)in PM_(2.5) in Chengde during the sampling period ranged from 2.7 to 246.4 ng·m^(-3),and a significant seasonal characteristic was observed,that is(136.8±52.1)ng·m^(-3)(winter)>(70.3±36.7)ng·m^(-3)(autumn)>(24.7±17.4)ng·m^(-3)(spring)>(13.7±9.4)ng·m^(-3)(summer).For the percentage of PAHs with different ring numbers in the total PAHs mass concentration,5-6 ring PAHs were the dominant components in four seasons,2-3 ring PAHs were of smaller proportion,and 4 ring PAHs were of the highest percentage in winter(37.63%).The contribution of crude oil and petroleum volatile spill emissions to PAHs was relatively high in spring and summer,and coal and biomass combustion emission sources were absolutely dominant in autumn and winter.BaP_(Teq) concentrations showed that winter>autumn>spring>summer.ILCR models pointed out that adults had higher respiratory exposure risk than that in children,and adults had different degrees of carcinogenic risk in spring and autumn and winter,whereas children had some degree of carcinogenic risk only in winter,and the variation in ILCR in all four seasons for both adults and children was ranked winter>autumn>spring>summer.