Concentrations and gas-particle partitioning of PCDD/Fs in the urban air of Dalian, China

QIN SongTao 2 3 ZHU XiuHua ) 2 3 WANG Wei 2 3 CHEN JiPing 1 2 NI YuWen 1 2 LI XiaoXiao 0 2 MU Jun 2 3 XU Qian 2 3 SCHRAMM Karl-Werner 2 4 0 Dalian Meteorological Observatory, Dalian 116001, China 1 Dalian Institute of Chemical Physics, Chinese Academy of Sciences , Dalian 116023, China 2 PCDD/Fs, urban air, gas-particle partitioning, Dalian 3 School of Environmental and Chemical Engineering, Dalian Jiaotong University , Dalian 116028, China 4 Helmholtz Center Munich-German Research Center for Environmental Health, Molecular EXposomics (MEX) , Ingolstdter Landstr. 1, 85764 Neuherberg, Germany PCDD/Fs in the urban air of Dalian, China were monitored with high-volume active sampler from November 2009 to October 2010. The concentration of Cl48DD/Fs ranged from 3065 to 49538 fg m3, with an average of 10249 fg m3. The international toxic equivalents (I-TEQ) value of that was 61.81182 fg m3, with an average of 235 fg m3, which was comparable to those in the other urban locations around the world. It was found that the Cl48DD/Fs appeared to be present mainly in the particle phase during winter, spring and autumn, while during summer which were dominantly in gas phase. The ratio of Cl48DD/Fs present in particle phase increased with the increasing level of chlorination. The concentrations of PCDFs and PCDDs decreased with the increase of chlorinated level, while the concentrations of 2,3,7,8-PCDDs congeners increased with the increase of chlorination level. The homolog profiles of the concentrations of PCDFs presented were higher than those of the PCDDs, which indicated the PCDD/Fs pollution source of the air in Dalian was characteristic for thermal source pollution. The correlation analysis of meteorological parameters with the concentrations of Cl48CDD/Fs was conducted using SPSS packages, and it was found that the ambient temperature and atmospheric pressure were important factors influence the concentration of PCDD/Fs in the air. The respiratory risk and intake dioxins of the residents around the sampling sites were studied in the paper. It was found that Junge-Pankow model was much more accurate in predicting the gas-particle partitioning behavior of PCDD/Fs homologues during winter, while the Harner-Bidleman model shows better agreement with the measured data during winter and summer. - Polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) are two species of persistent organic pollutants (POPs) in the environment. PCDD/Fs have received considerable public and scientific attention because of the acute toxicity of 2,3,7,8-tetrachlorodibenzop-dioxin (2,3,7,8-TCDD) [1]. Due to their persistence and semivolatility, they can be transported over long distance on a global scale. Atmospheric transport is a primary pathway for the transfer of semivolatile organic compounds (SVOCs) to the terrestrial and aquatic ecosystems via deposition [2,3]. A key process in determining the environmental fate of organic chemicals in the atmosphere is their partitioning between particle and gas phase. Wet and dry deposition, photolysis, and reaction with OH radicals act differently on gasand particle-bound SVOCs, thereby affecting the efficiency and scope of their long-range atmospheric transport. Meanwhile, the gas-particle partitioning also influences the degradation processes, chemical reactions, and long-range The Author(s) 2012. This article is published with open access at Springerlink.com transport, and human and ecosystem health effects of atmospheric SVOCs [46]. At present, there are two main sorption models which have been used to describe gas/particle partitioning of PCDD/Fs, i.e. the Junge-Pankow model, adsorption to the particle surface using the subcooled liquid vapor pressure of the compounds (PL0) [7,8] and the HarnerBidleman model, absorption to the organic phase of aerosols using the octanol-air partition coefficient (Koa) [9]. Absorptive partitioning is believed to be the dominant mechanism when an organic fraction exists on the aerosol [10,11]. Despite the recent efforts to investigate the occurrences of PCDD/Fs in the regional environment in China, including water, soil, sediments and pine (Cedrus deodara) needles [1217], very little was known about the levels of PCDD/Fs in the regional atmospheric environment in China [3,1820], except those in Hong Kong and Taiwan [21,22] (http://www.epd-asg.gov.hk/english/report/dioxin.php). Dalian (1205812331E, 38434010N) is a seaside city located on the southern tip of the Eastern Liaoning Peninsula of the northeast of China. Dalian, a typical metropolis of China, has a population of over six millions. The area of Dalian is 12574 km2 and its urban area is 2415 km2. Petrochemical industry, modern equipment manufacturing, ship building, electronic information industry are the four pillar industries of Dalian. Although, Dalian is one of the most livable cities in China, there are also some kinds of dispersed sources to produce PCDD/Fs that affect the air quality, such as motor vehicle exhausts, industrial emissions, winter heating, etc. To our knowledge, monitoring of PCDD/ Fs of the urban air of Dalian for the whole year has not been investigated so far [20]. The objectives of this study were to measure the concentrations of PCDD/Fs in the urban air of Dalian, to investigate the gas-particle distribution of PCDD/Fs in the air and the relations of which with the meteorological parameters, and to evaluate the exposure risk of the local residents in the pollutant air. Furthermore, the relative performances of Junge-Pankow and Harner-Bidleman models in evaluating the gas-particle partitioning behavior of PCDD/Fs during the four seasons were assessed. Materials and methods The sampling process was conducted according to US EPA compendium method TO 9A. From November 2009 to October 2010 (except February 2010, the Chinese Spring Festival holiday), active high-volume air samplings (ECHO HiVol, TCR TECORA, Italy) were carried out at two sites in Dalian, China, which were selected based on their different surrounding environments, populations and traffic densities. The sampling sites were the rooftops of the No.1 building at Dalian Jiaotong University (DJU: 12154.399E, 3834.286N, elevation 32 m) and the building of Dalian Meteorological Observatory (DMO: 12138.730E, 3854.174N, elevation 113 m). DMO is located at a hillside. Surroundings of this site include residential buildings, university campus, a road with light traffic (Jiefang road is about 0.27 km from DMO) and a vast expanse of mountain, on which there are many trees and plants. The site is not far from Dalian port (DLP), which is about 3 km from DMO. DLP is a world-known deep and ice-free harbor, having shipping relations with over 160 countries and regions and undertaking more than 70% of cargo transportation. Dalian Newport (DNP) is a modern deepwater oil port, which is about 24 km from DMO. DJU is located in the campus of Dalian Jiaotong University whi (...truncated)