Source characterization of ambient fine particles at multiple sites in the Seattle area

To identify major PM_2.5 (particulate matter ≤2.5 μm in aerodynamic diameter) sources with a particular emphasis on the ship engine emissions from a major port, integrated 24 h PM_2.5 speciation data collected between 2000 and 2005 at five United State Environmental Protection Agency's Speciation Trends Network monitoring sites in Seattle, WA were analyzed. Seven to ten PM_2.5 sources were identified through the application of positive matrix factorization (PMF). Secondary particles (12–26% for secondary nitrate; 17–20% for secondary sulfate) and gasoline vehicle emissions (13–31%) made the largest contributions to the PM_2.5 mass concentrations at all of the monitoring sites except for the residential Lake Forest site, where wood smoke contributed the most PM_2.5 mass (31%). Other identified sources include diesel vehicle emissions, airborne soil, residual oil combustion, sea salt, aged sea salt, metal processing, and cement kiln. Residual oil combustion sources identified at multiple monitoring sites point clearly to the Port of Seattle suggesting ship emissions as the source of oil combustion particles. In addition, the relationship between sulfate concentrations and the oil combustion emissions indicated contributions of ship emissions to the local sulfate concentrations. The analysis of spatial variability of PM_2.5 sources shows that the spatial distributions of several PM_2.5 sources were heterogeneous within a given air shed.     

Coupled infrared extinction spectra and size distribution measurements for several non-clay components of mineral dust aerosol (quartz, calcite, and dolomite)

Simultaneous size distributions and Fourier transform infrared (FTIR) extinction spectra have been measured for several representative components of mineral dust aerosol (quartz, calcite, and dolomite) in the fine particle size mode (D=0.1–1 μm). Optical constants drawn from the published literature have been used in combination with the experimentally determined size distributions to simulate the extinction spectra. In general, Mie theory does not accurately reproduce the peak position or band shape for the prominent IR resonance features in the 800–1600 cm⁻¹ spectral range. The resonance peaks in the Mie simulation are consistently blue shifted relative to the experimental spectra by 20–50 cm⁻¹. Spectral simulations, derived from a simple Rayleigh-based analytic theory for a “continuous distribution of ellipsoids” particle shape model, better reproduce the experimental spectra, despite the fact that the Rayleigh approximation is not strictly satisfied in these experiments. These results differ from our previous studies of particle shape effects in silicate clay mineral dust aerosols where a disk-shaped model for the particles was found to be more appropriate.     

Seasonal variation in dissolved gaseous mercury and total mercury concentrations in Juam Reservoir, Korea

Dissolved gaseous mercury (DGM) and total mercury (TM) concentrations were measured in Juam Reservoir, Korea. DGM concentrations were higher in spring (64+/-13pgL(-1)) and summer (109+/-15pgL(-1)), and lower in fall (20+/-2pgL(-1)) and winter (23+/-6pgL(-1)). In contrast, TM concentrations were higher in fall (3.2+/-0.1ngL(-1)) and winter (3.3+/-0.1ngL(-1)) than in spring (2.3+/-0.1ngL(-1)) and summer (2.2+/-0.4ngL(-1)). DGM concentrations were correlated with water temperature (p<0.0001), ORP (p<0.0001), UV intensity (UV-A: p=0.008; UV-B: p=0.003), and DOC concentration (p=0.0107). DGM concentrations varied diurnally with UV intensity. The average summer DGM (109+/-15pgL(-1)) and TM (2.2+/-0.4ngL(-1)) concentrations in Juam Reservoir were higher than the averages for North American lakes (DGM=38+/-16pgL(-1); TM=1.0+/-1.2ngL(-1)), but lower than levels reported for Baihua Reservoir in China.     

Chlorinated naphthalene formation from the oxidation of dichlorophenols

Polychlorinated naphthalenes (PCNs) formed along with dibenzo-p-dioxin and dibenzofuran products in the slow combustion of dichlorophenols (DCPs) at 600 degrees C were identified. Each DCP reactant produced a unique set of PCN products. Major PCN congeners observed in the experiments were consistent with products predicted from a mechanism involving an intermediate formed by ortho-ortho carbon coupling of phenoxy radicals; polychlorinated dibenzofurans (PCDFs) are formed from the same intermediate. Tautomerization of the intermediate and H2O elimination produces PCDFs; alternatively, CO elimination to form dihydrofulvalene and fusion produces naphthalenes. Only trace amounts of tetrachloronaphthalene congeners were formed, suggesting that the preferred PCN formation pathways from chlorinated phenols involve loss of chlorine. 3,4-DCP produced the largest yields of PCDF and PCN products with two or more chlorine substituents. 2,6-DCP did not produce tri- or tetra-chlorinated PCDF or PCN congeners. It did produce 1,8-DCN, however, which could not be explained.     

Ambient air monitoring of PCDD/Fs and co-PCBs in Gyeonggi-do, Korea

We started the monitoring for PCDD/Fs in ambient air and soil in August 2001, and co-PCBs in January 2002. Decreasing of PCDD/Fs and co-PCBs levels in ambient air were observed. The higher PCDD/Fs levels were found in winter and lower in autumn. We found that the industrial incinerators influenced the PCDD/Fs levels in ambient air. In the 2,3,7,8-substituted PCDD/Fs concentration profiles, the three major congeners occupied 67% of the total mass. In case of co-PCBs, PCB#118, #105 and #77 were observed as the main congeners. Five cluster groups discriminated by ratio of four components, O(8)CDD, 1,2,3,4,6,7,8-H(7)CDD, 1,2,3,4,6,7,8-H(7)CDF and O(8)CDF, were obtained from HCA (hierarchical cluster analysis).     

Characterization of PM2.5 aerosols dominated by local pollution and Asian dust observed at an urban site in Korea during aerosol characterization experiments (ACE)--Asia Project

Daily fine particulate matter (PM2.5) samples were collected at Gwangju, Korea, during the Aerosol Characterization Experiments (ACE)-Asia Project to determine the chemical properties of PM2.5 originating from local pollution and Asian dust (AD) storms. During the study period, two significant events occurred on April 10-13 and 24-25, 2001, and a minor event occurred on April 19, 2001. Based on air mass transport pathways identified by back-trajectory calculation, the PM2.5 dataset was classified into three types of aerosol populations: local pollution and two AD aerosol types. The two AD types were transported along different pathways. One originated from Gobi desert area in Mongolia, passing through Hunshandake desert in Northern Inner Mongolia, urban and polluted regions of China (AD1), and the other originated in sandy deserts located in the Northeast Inner Mongolia Plateau and then flowed southward through the Korean peninsula (AD2). During the AD2 event, a smoke plume that originated in North Korea was transported to our study site. Mass balance closures show that crustal materials were the most significant species during both AD events, contributing -48% to the PM2.5 mass; sulfate aerosols (19.1%) and organic matter (OM; 24.6%) were the second greatest contributors during the AD1 and AD2 periods, respectively, indicating that aerosol properties were dependent on the transport pathway. The sulfate concentration constituted only 6.4% (4.5 microg/m3) of the AD2 PM2.5 mass. OM was the major chemical species in the local pollution-dominated PM2.5 aerosols, accounting for 28.7% of the measured PM2.5 mass, followed by sulfate (21.4%), nitrate (15%), ammonium (12.8%), elemental carbon (8.9%), and crustal material (6.5%). Together with substantial enhancement of the crustal elements (Mg, Al, K, Ca, Sc, Ti, Mn, Fe, Sr, Zr, Ba, and Ce), higher concentrations of pollution elements (S, V, Ni, Zn, As, Cd, and Pb) were observed during AD1 and AD2 than during the local pollution period, indicating that, in addition to crustal material, the AD dust storms also had a significant influence on anthropogenic elements.     

Identification and interpretation of representative ozone distributions in association with the sea breeze from different synoptic winds over the coastal urban area in Korea

To aid the studies of long-term impact assessment of cumulative ozone (O3) exposures, the representative 8-hr O3 pollution patterns have been identified over the Greater Seoul Area (GSA) in Korea. Principal component analysis and two-stage clustering techniques were used to identify the representative O3 patterns, and numerical and observational analyses were also used to interpret the identified horizontal distribution patterns. The results yielded three major O3 distribution patterns, and each of the three patterns was found to have strong correlations with local and synoptic meteorological conditions over the GSA. For example, pattern 1, accounting for 46% of O3 concentration distributions, mostly occurred under relatively weak westerly synoptic winds. The predominant features of this pattern were infrequent high O3 levels but a distinct gradient of O3 concentration from the western coastal area to the eastern inland area that was mainly induced by the local sea breeze. Pattern 2, accounting for 31% of O3 concentration distributions, was found with higher O3 levels in the western coastal area but lower in the eastern inland area. This is due to the modified sea breeze under the relatively stronger easterly opposing synoptic wind, affecting the high O3 occurrence in the western coastal area only. However, pattern 3, accounting for 21% of O3 concentration distributions, showed significantly higher O3 concentrations over the whole GSA mainly due to the retarded and slow-moving sea-breeze front under the weak opposing synoptic flow. Modeling study also indicated that local and synoptic meteorological processes play a major role in determining the high O3 concentration distribution patterns over the GSA.     

Background levels and dietary intake of PCDD/Fs in domestic and imported meat in South Korea

A survey was conducted in South Korea to determine residual levels and dietary intake of polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) from meat. Altogether 119 domestic and 164 imported samples of beef, pork, and chicken were examined. The mean levels of PCDD/Fs in upper bound were 0.21, 0.22, and 0.04pg WHO-TEQ/g fat for beef, pork, and chicken, respectively. The low level of PCDD/Fs in chicken probably resulted from the low fat content in the samples used. The samples were separated into domestic and imported products in order to investigate the sources of contamination. PCDFs were the more dominant congeners in domestic beef and were similar to those found from emission of incineration. However, the congener profiles of domestic beef and incineration were difficult to compare because the environmental fate and animal metabolism were involved. The upper bound dietary intake of PCDD/Fs from beef, pork and chicken was calculated to be 0.04pg/WHO-TEQ/kgbw/day. The combined consumption of beef, pork, and chicken was found to be 84.8g per day for a person weighing 60kg and represented 5.7% of their total daily food intake.     

Identification of potential biomarkers for diazinon exposure to Japanese Medaka (Oryzias latipes) using annealing control primers

A new differential display-polymerase chain reaction (PCR) method based on annealing control primers was used to screen and identify potential biomarkers from differentially expressed genes (DEGs) in medaka exposed to sub-lethal concentration of diazinon (100 ppb). Among the differentially expressed genes identified, the majority were in functional categories of protein biosynthesis, transport and metabolism according to the gene ontology classification. The differential expression of ribosomal protein genes was quantified by real time PCR. The genes encoding ribosomal proteins including L3 and S17 were selected as potential biomarkers for diazinon exposure in medaka fish.