atmosphere Article Polycyclic Aromatic Hydrocarbons in PM2.5 and PM2.5–10 in Urumqi, China: Temporal Variations, Health Risk, and Sources Suwubinuer Rekefu 1, Dilinuer Talifu 1,*, Bo Gao 2,*, Yusan Turap 1, Mailikezhati Maihemuti 1, Xinming Wang 3 and Abulikemu Abulizi 1 1 Key Laboratory of Coal Clean Conversion and Chemical Engineering Process, Xinjiang Uyghur Autonomous Region, College of Chemistry and Chemical Engineering, Xinjiang University, Urumqi 830046, China; [email protected] (S.R.); [email protected] (Y.T.); [email protected] (M.M.); [email protected] (A.A.) 2 State Environmental Protection Key Laboratory of Urban Environment & Ecology, South China Institute of Environmental Sciences, Ministry of Environmental Protection, Guangzhou 510535, China 3 State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China; [email protected] * Correspondence: [email protected] (D.T.); [email protected] (B.G.); Tel.: +86-0991-8813938 (D.T.); +86-20-29119655 (B.G.); Fax: +8620-85524451 (B.G.) Received: 21 July 2018; Accepted: 18 October 2018; Published: 22 October 2018 Abstract: PM2.5 and PM2.5–10 samples were simultaneously collected in Urumqi from January to December 2011, and 14 priority polycyclic aromatic hydrocarbons (PAHs) were determined. The mean −3 −3 concentrations of total PAHs in PM2.5 and PM2.5–10 were 20.90~844.22 ng m and 19.65~176.5 ng m respectively, with the highest in winter and the lowest in summer. Above 80% of PAHs were enriched in PM2.5, which showed remarkable seasonal variations compared to coarse particles. High molecular weight (HMW) PAHs were predominant in PM2.5 (46.61~85.13%), whereas the proportions of lower molecular weight (LMW) and HMW PAHs in PM2.5–10 showed a decreasing and an increasing trend, respectively, from spring to winter. The estimated concentrations of benzo[a]pyrene equivalent −3 carcinogenic potency (BaPeq) in PM2.5 (10.49~84.52 ng m ) were higher than that of in PM2.5–10 −3 (1.15~13.33 ng m ) except in summer. The estimated value of inhalation cancer risk in PM2.5 and −4 −3 −5 −3 PM2.5–10 were 1.63 × 10 ~7.35 × 10 and 9.94 × 10 ~1.16 × 10 , respectively, far exceeding the health-based guideline level of 10−4. Diagnostic ratios and positive matrix factorization results demonstrated that PAHs in PM2.5 and PM2.5–10 were from similar sources, such as coal combustion, biomass burning, coking, and petroleum combustion, respectively. Coal combustion was the most important source for PAHs both in PM2.5 and PM2.5–10, accounting for 54.20% and 50.29%, respectively. Keywords: PAHs; particulate matter; particle size distribution; sources 1. Introduction Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous constituents of particulate matter in the atmosphere and well-known to be carcinogenic and/or mutagenic [1,2], and are emitted into the atmosphere from natural as well as anthropogenic sources. Natural sources include forest fires and volcanic eruptions, while anthropogenic sources include meat cooking, motor vehicles, road dust (including particles generated by tire wear and brake lining erosion), natural gas home appliances, tobacco smoke, asphalt, boilers, coal combustion, wood burning [3,4], solid waste incineration, and petroleum spills and discharge [5]. Atmosphere 2018, 9, 412; doi:10.3390/atmos9100412 www.mdpi.com/journal/atmosphere Atmosphere 2018, 9, x 2 of 13 Atmosphere 2018, 9, 412 2 of 13 tobacco smoke, asphalt, boilers, coal combustion, wood burning [3,4], solid waste incineration, and petroleum spills and discharge [5]. Urumqi, the capital of Xinjiang Uygur Autonomous Region Region of of China, China, is is in in central Xinjiang, which is on the north foot of Tianshan Mountain andand the south edge of Jungger Basin. It is located in the center of Asia, Asia, north north of of the the Taklimakan Taklimakan desert desert and and south south of of the the Gurbantunggut Gurbantunggut desert desert (Figure (Figure 11).). Three sides of it are surrounded by the Tianshan Moun Mountain,tain, of which the the highest highest elevation elevation is is 5000 5000 m. m. The particles are brought into the urban area fromfrom the Quasigeer basin through the north–south route [[6,7].6,7]. RapidRapid economiceconomic developmentdevelopment has has caused caused more more and and more more serious serious air air pollution pollution problems problems in inUrumqi, Urumqi, which which is one is ofone the of most the pollutedmost polluted citiesduring cities during winter inwinter China in [8 ].China During [8]. the During six months the six of monthsheating, of the heating, city was the covered city was by thecovered haze by for the at least haze one for thirdat least of theone time. third Li of et the al. time. (2008) Li reported et al. (2008) that −3 reportedthe mean that concentrations the mean concentrations of PM10 in the of winter PM10 in of the 2006 winter in Urumqi of 2006 was in 305.6Urumqiµg was m 305.6with aµg maximum m−3 with −3 aof maximum 1048.5 µg of m 1048.5, and µg the m mean−3, and concentrations the mean concentrations of PM2.5 (particle of PM diameter2.5 (particle≤ diameter2.5 µm) and ≤2.5 TSP µm) (Total and TSPSuspended (Total Suspended Particulate, Partic particleulate, diameter particle ≤diameter100 µm) ≤ in100 the µm) winter in the of winter 2007 were of 2007 187 were and 187 385 andµg m 385−3 − withµg m− a3 maximumwith a maximum of 487 of and 487 1313 andµ 1313g m µg3, respectively,m−3, respectively, far higher far higher than than the Nationalthe National Ambient Ambient Air AirQuality Quality Standard Standard of China of China [6]. [6]. Figure 1. Location of sampling site. Research on atmospheric PAHs PAHs in China is main mainlyly focused on the Yangtze River Delta and the Pearl River River Delta Delta region region [9–14]. [9–14 ].In Incontrast, contrast, much much fewer fewer studies studies (most (most published published in Chinese) in Chinese) have havebeen carriedbeen carried out in outUrumqi in Urumqi [7,8,15–20]. [7,8, 15Early,–20]. Peng Early, et al. Peng (2006) et al. analyzed (2006) the analyzed sources the of PAHs sources in ofTSP PAHs and in PMTSP10and in Urumqi in PM10 within Urumqi the composition with the compositionof carbon isotop of carbone [20]. Diao isotope et al. [20 (2005)]. Diao analyzed et al. (2005) PAHs analyzed using a GC/MSPAHs using technique a GC/MS in Urumqi technique Xinshi in Urumqidistrict Xinshifrom December district from 2004 December to January 2004 2005 to January(winter) 2005and reported(winter) andthat reportedthe major that source the majorof PAHs source in Urumqi of PAHs Xinshi in Urumqi district Xinshi was coal district combustion was coal combustionand vehicle exhaustand vehicle [15]. exhaustLately, Limu [15]. et Lately, al. (2013) Limu analyzed et al. (2013)the PAHs analyzed in PM2.5 the and PAHs PM2.5–10 in PM in Urumqi’s2.5 and PM southern2.5–10 in urbanUrumqi’s area southern from 26 September urban area 2010 from to 26 3 SeptemberMarch 2011 2010 (autumn to 3 March and wintertime) 2011 (autumn [7]. andThe wintertime)results showed [7]. −3 thatThe resultsthe ΣPAHs showed (sum that of 15 the PAHs)SPAHs ranged (sum from of 15 0.11 PAHs) to 1058.08 ranged ng from m−3 0.11in PM to2.5 1058.08 and 0.01 ng to m 90.89in ng PM m2.5−3 −3 inand PM 0.012.5–10 to, respectively, 90.89 ng m andin PM 90%2.5–10 of the, respectively, ΣPAHs existed and 90%in PM of2.5 the. TheSPAHs above existed studies in were PM2.5 based. The on above the winterstudies or were autumn based seasons, on the and winter the source or autumn analysis seasons, of PAHs and in the Urumqi source was analysis limited of to PAHs the ratio in Urumqiand the wasprincipal limited component to the ratio analysis and the methods. principal Although component Ren analysiset al. (2017) methods. reported Although particle Rensize distribution et al. (2017) ofreported PAHs in particle the atmosphere size distribution of Urum ofqi PAHsand analyzed in the atmosphere their source ofusing Urumqi the Positive and analyzed Matrix Factorization their source (usingPMF) themodel, Positive it was Matrix also Factorizationlimited to the (PMF) heating model, season it was[8]. alsoUrumqi limited belongs to the to heatingtypical seasontemperate [8]. semiaridUrumqibelongs continental to typical climate, temperate with a large semiarid temperature continental difference climate, be withtween a largewinter temperature and summer. difference Winter isbetween long and winter cold, and the summer. temperature Winter is is stable. long andIt is cold,windy and in spring the temperature and autumn, is stable.and the It precipitation is windy in isspring concentrated and autumn, in summer, and the precipitation which has isthe concentrated effect of washing in summer, and which purifying has the pollutants effect of washing in the atmosphere.and purifying The pollutants pollution in characteristics the atmosphere. of The PAHs pollution in different characteristics seasons may of PAHs varyin greatly. different However, seasons tomay date, vary there greatly. are few However, detailed to studies date, there about are the few pollut detailedion levels, studies particle about thesize pollution distributions, levels, temporal particle variations,size distributions, health risk, temporal identification, variations, and health apportionment risk, identification, of the specific and apportionment pollution sources of the of specific PAHs Atmosphere 2018, 9, 412 3 of 13 pollution sources of PAHs using PMF model in PM2.5 and PM2.5–10 in Urumqi throughout the year. Our study sought to fill this knowledge gap. 2.