[Photochemical Mechanism and Control Strategy Optimization for Summertime Ozone Pollution in an Industrial City in the North China Plain].

To investigate the characteristics and formation mechanism of ozone (O3) pollution in an industrial city, an extensive one-month field campaign focusing on O3 and its precursors (e.g., volatile organic compounds[VOC] and nitrogen oxides[NOx]) was conducted in Zibo City, a highly industrializd city in the North China Plain, in June 2021. The 0-D box model incorporating the latest explicit chemical mechanism (MCMv3.3.1) was applied using an observation dataset (e.g., VOC, NOx, HONO, and PAN) as model contraints to explore the optimal reduction strategy for O3 and its precursors. The results showed that ① during high-O3 episodes, stagnant weather conditions with high temperature and solar radiation as well as low relative humidity were observed, and oxygenated VOCs and alkenes from anthropogenic VOCs contributed the most to the total ozone formation potential and OH reactivity (k·OH). ② The in-situ O3 variation was primarily affected by local photochemical production and export process horizontal to downwind areas or vertical to the upper layer. The reduction in local emissions was essential to alleviate O3 pollution in this region. ③ During high-O3 episodes, high concentrations of ·OH (10×106 cm-3) and HO2· (14×108 cm-3) radical drove and generated a high O3 production rate (daytime peak value reached 36×10-9 h-1). The reaction pathways of HO2·+NO and ·OH+NO2 contributed the most to the in-situ gross Ox photochemical production (63%) and photochemical destruction (50%), respectively. ④ Compared to those during low-O3 episodes, the photochemical regimes during high-O3 episodes were more inclined to be considered as the NOx-limited regime. Detailed mechanism modeling based on multiple scenarios further suggested that the synergic emission reduction strategy of NOx and VOC, while focusing on NOx emission alleviation, would be practical options for controlling local O3 pollutions. This method could also provide policy-related guidance for the precise O3 pollution prevention and control in other industrialized Chinese cities.

[Size Distribution and Source Appointment of Road Particles During Winter in Tianjin].

The significant role of traffic emissions mixed from various sources in urban air pollution has been widely recognized. However, the corresponding contributions to the roadside particle distribution are poorly understood due to the mixed impacts of various sources. Particle number concentrations of different sizes at the roadside in Nankai District of Tianjin were continuously monitored using a portable aerosol particle spectrometer during the morning rush hour (07:30-09:20) from Nov. 9, 2018 to Jan. 6, 2019. Characteristic and influencing factors of particle size distributions were discussed combined with temperature and relative humidity data, while potential sources of particles at the roadside were identified based on size distribution analysis. The results showed that the average total particle number concentrations were 502 cm-3, and the concentrations of the accumulation mode and coarse mode were 500 cm-3 and 2 cm-3, respectively. The distribution of number concentrations at the roadside was unimodal and primarily concentrated at 0.25-0.50 µm, with peak sizes at 0.28-0.30 µm. The same distribution trend of particle number concentration and difference in the concentration in the same segment size were observed at different periods. Vehicle activity level was the main influencing factor of road particulate matter concentration on different weekdays; the probability of the high value of road particulate matter concentration was reduced by a reasonable combination of the vehicle tail numbers. Temperature and relative humidity were both found to be positively correlated with the number concentration of particles. With the increase in temperature and relative humidity, the total and peak particle number concentration showed an overall upward trend. In addition, the peak particle size increased from 0.28-0.30 µm to 0.35-0.40 µm when relative humidity was higher than 80%. Three sources, including road dust, brake and tire wear, and the aging particles from vehicle exhaust, were identified using positive matrix factorization in this study. Road dust contributed 8.6% of the total number concentration, which mainly consisted of particles with sizes above 5.00 µm. Brake and tire wear contributed 2.8% of the total number concentration of particles with a size range of 0.80-4.00 µm. The aging particles from vehicle exhaust contributed the most (88.5%), with a peak at 0.25-0.65 µm. The sources of roadside particles were mainly related to vehicle activity, whereas temperature and relative humidity also affected the particle number size distribution.

[Source and Health Risk Assessment of PM2.5-Bound Metallic Elements in Road Dust in Zibo City].

To study the pollution characteristics, sources, and ecological and health risk of PM2.5-bound metallic elements in road dust in Zibo City, a total of 97 dust samples were collected in eight districts between October 2016 and May 2017, and particles smaller than 2.5 µm were suspended filtered using a resuspension system. Inductively coupled plasma mass spectrometry (ICP-MS) and optical emission spectrometry (ICP-OES) were used to investigate 18 metal elements within the dust samples. The results showed that the mass fraction of Ca[ω(Ca)] was highest with an average of 120307.7 mg·kg-1, which was 7.2 times higher than the soil background values for Shandong Province. The mean values of ω(Zn), ω(Cu), ω(Sb), and ω(Cd) were 13.9, 11.7, 13.3, and 29.6 times higher than the background values, respectively. The geo-accumulation index (Igeo) indicated high levels of Cd, Zn, Cu, and Sb pollution, especially in winter. Enrichment factors (EFs) also indicated high concentrations of Cd, Zn, Sb, and Cu in the road dust, which were notably affected by human activities. Principal component analysis (PCA) showed that biomass combustion, coal burning, vehicle emissions, iron and steel smelting, and soil dust are the five main sources of metal elements in road dust in Zibo City. The potential ecological risk of Cd and the total potential risk were extremely high during three seasons and was highest in winter. Health risk assessment showed that As and Pb had a non-carcinogenic risk for children, while Cr presents a carcinogenic risk. In conclusion, pollution from PM2.5-bound metallic elements in road dust in Zibo City is derived from anthropogenic sources and is most severe during winter. Importantly, the levels of pollution detected represent potential ecological risk as well as some non-carcinogenic and carcinogenic risks for children. Therefore, the source control of road dust requires particular attention.

Nitrogen isotope differences between atmospheric nitrate and corresponding nitrogen oxides: A new constraint using oxygen isotopes.

Tracking of reactive nitrogen (N) sources is important for the effective mitigation of N emissions. By combining the N and oxygen (O) isotopes of atmospheric NO3-, stable isotope mixing models were recently applied to evaluate the relative contributions of major NOx sources. However, it has long been unresolved how to accurately constrain the δ15N differences between NO3- and corresponding NOx (ε(NO2→NO3-) values). Here, we first incorporated the HC oxidation (NO2 → NO3-) pathway by using Δ17O values to evaluate the ε(NO2→NO3-) values, performed on NO3- in PM2.5 collected during the day and at night from January 4-13, 2015 at an urban site in Beijing. We found that the Δ17O-based ε values (ε17O-based(NO2→NO3-)) (15.6 ±â€¯7.4‰) differed distinctly from δ18O-based ε values (ε18O-based(NO2→NO3-)) (33.0 ±â€¯9.5‰) so did not properly incorporate the isotopic effects of the HC oxidation (NO2 → NO3-) pathway. Based on the ε(NO2→NO3-) values, δ15N values of NOx from coal combustion (CC), vehicle exhausts (VE), biomass burning (BB), and the microbial N cycle (MC), as well as NO3- in PM2.5, we further quantified the source contributions by using Stable Isotope Analysis in R (the SIAR model). We found that the respective fractional contributions of CC-NOx and MC-NOx were underestimated by 64% and were overestimated by 216% by using ε18O-based(NO2→NO3-) values. We concluded that the new ε17O-based(NO2→NO3-) values reduced uncertainties in contribution analysis and the evaluation method for atmospheric NO3- sources.

[Emission Characteristics of Exhaust PM and Its Carbonaceous Components from China â ¢ to China â £ Diesel Vehicles in Shenyang].

Diesel vehicles were the primary source of atmospheric particulate matter (PM) emitted by motor vehicles. To study the emission factors and carbon components of PM2.5 and PM10 from diesel vehicles in Shenyang, exhaust PM samples were collected from 15 diesel vehicles including small, medium, and large passenger vehicles, and light, medium, and heavy-duty trucks under China Ⅲ and China Ⅳ emission standards. This was undertaken using a dilution channel sampling system, and the carbon components were also analyzed. The results showed that the average distance-based PM2.5 and PM10 emission factors for diesel vehicles under China Ⅲ were (0.193±0.092) g·km-1 and (0.338±0.305) g·km-1, respectively, and for China Ⅳ were (0.085±0.038) g·km-1 and (0.100±0.042) g·km-1, respectively. This shows that the PM emission factors decreased significantly with the improvement of emission standards. Under the same emission standards, emission factors increased with the increase of vehicle passenger volume or cargo capacity. TC (total carbon) was the main component of the emissions from diesel vehicles. The mass fraction of TC under China Ⅳ (23%-48%) was significantly lower than under China Ⅲ (29%-70%). The mass fraction of elemental carbon (EC) for all types of diesel vehicles was greater than organic carbon (OC). The OC/EC value was 0.70±0.29, and the OC/EC value for diesel vehicles under China Ⅳ was lower than under China Ⅲ. The total mileage of passenger vehicles was significantly higher than that of trucks, resulting in higher fuel consumption. The mass fraction of OC and EC in passenger vehicles was higher than for trucks under the same emission standards. EC2 (elemental carbon which was measured at temperatures of 700℃) was the highest carbon content of diesel vehicles under China Ⅲ and China Ⅳ emission standards, which can be used in the identification of diesel vehicles in source apportionment studies.

[Source Apportionment and Pollution Characteristics of PM2.5 During the Two Heavy Pollution Episodes in the Winter of 2016 in a Typical Logistics City].

To characterize the chemical composition of PM2.5 and the formation of pollution during a heavy pollution episode in the winter in a typical logistics city, PM2.5 samples were collected from December 2016 to January 2017 at six sampling sites, and the water-soluble ions, elements, and carbon components were determined. The results showed that the average concentration of PM2.5 was (145.2±87.8) µg·m-3 during the whole sampling period, of which 82% of daily average concentrations were above class Ⅱ of the national standards. The average concentrations of PM2.5 during the two heavy pollution episodes were (187.3±79.8) and (205.3±92.0) µg·m-3, which were 5.4 and 5.9 times, respectively, as high as class Ⅱ of the national standard. The results of the chemical composition of the PM2.5 showed that secondary water-soluble inorganic ions (SO42-, NO3-, and NH4+) were the main components of PM2.5 in winter (51.2% of PM2.5 mass concentration), followed by organic matter (OM, 23.8%), and mineral dust (12.7%). Combined with the change trend and accumulation rate of chemical components during the pollution episode, we discovered that the increasing of SNA and OM led to PM2.5 pollution in the first episode, while the growth of SNA caused the second pollution episode. This was further verified by the synchronous change of SOR, NOR, and the OC/EC ratio. PMF analysis indicated that mixed sources of secondary particulate matter and biomass combustion (50.0%), coal combustion (16.8%), vehicles (12.9%), fugitive dust (10.0%), industry (5.3%) and soil dust (5.0%), were the main sources of PM2.5 of Linyi city in the winter. Compared with the average concentration over the whole sampling period, the contribution of secondary particles during the two pollution episodes was significantly increased. This indicates that the formation and accumulation of secondary particulate matter under static and humid meteorological conditions were the main influencing factors during the heavy pollution episodes.

Isotopic evaluation on relative contributions of major NOx sources to nitrate of PM2.5 in Beijing.

Nitrate (NO3-) is a key component of secondary inorganic aerosols and PM2.5. However, the contributions of nitrogen oxides (NOx) emission sources to NO3- in PM2.5 remain poorly constrained. This study measured nitrogen (N) isotopes of NO3- (hereafter as δ15N-NO3-) in PM2.5 collected at Beijing in 2014. We observed that δ15N-NO3- values in PM2.5 (-2.3‰â€¯- 19.7‰; 7.3 ±â€¯5.4‰ annually) were significantly higher in winter (11.9 ±â€¯4.4‰) than in summer (2.2 ±â€¯2.5‰). The δ15N differences between source NOx and NO3- in PM2.5 (hereafter as Δ values) were estimated by a computation module as 7.8 ±â€¯2.2‰â€¯- 10.4 ±â€¯1.6‰ (8.8 ±â€¯2.4‰). Using the Δ values and δ15N values of NOx from major fossil (coal combustion, vehicle exhausts) and non-fossil sources (biomass burning, microbial N cycle), contributions of major NOx sources to NO3- in PM2.5 were further estimated by the SIAR model. We found that seasonal variations of δ15N-NO3- values in PM2.5 of Beijing were mainly caused by those of NOx contributions from coal combustion (38 ±â€¯10% in winter, 20 ±â€¯9% in summer). Annually, NOx from coal combustion, vehicle exhausts, biomass burning, and microbial N cycle contributed 28 ±â€¯12%, 29 ±â€¯17%, 27 ±â€¯15%, and 16 ±â€¯7% to NO3- in PM2.5, respectively, showing actually comparable contributions between non-fossil NOx (43 ±â€¯16%) and fossil NOx (57 ±â€¯21%). These results are useful for planning the reduction of NOx emissions in city environments and for elucidating relationships between regional NOx emissions and atmospheric NO3- pollution or deposition.

[Seasonal Variation Characteristics and Potential Source Contribution of Sulfate, Nitrate and Ammonium in Beijing by Using Single Particle Aerosol Mass Spectrometry].

Single particle aerosol mass spectrometry (SPAMS) was deployed to continuously observe the aerosol particles of Beijing urban area from 2013-12 to 2014-11, and the hourly average data of sulfate, nitrate and ammonium (SNA) were obtained using the characteristic ion tracer method. The mixing state and size distribution of SNA were analyzed. In addition, based on Hysplit 48 h back air mass trajectory results in combination with Concentration Weighted Trajectory method (CWT), we obtained the seasonal potential source contribution area of SNA. The results showed that the mixture of sulfate, nitrate and ammonium in spring and summer was more stable than that in autumn and winter. The size distribution of sulfate and nitrate was very similar. The size distribution characteristics of SNA followed the order of autumn > summer > spring > winter. The potential source region of SNA had similar spatial distribution characteristics, and the potential source region of SNA was mainly located in Beijing and south areas, especially at Tianjin, Langfang, Hengshui, Baoding and Shijiazhuang.

Long-term exposure to urban air pollution and lung cancer mortality: A 12-year cohort study in Northern China.

Cohort evidence that links long-term exposures to air pollution and mortality comes largely from the United States and European countries. We investigated the relationship between long-term exposures to particulate matter <10µm in diameter (PM10), nitrogen dioxide (NO2), and sulfur dioxide (SO2) and mortality of lung cancer in Northern China. A cohort of 39,054 participants were followed during 1998-2009. Annual average concentrations for PM10, NO2, and SO2 were determined based on data collected from central monitoring stations. Lung cancer deaths (n=140) were obtained from death certificates, and hazard ratios (HRs) were estimated using Cox proportional hazards models, adjusting for age, gender, BMI, education, marital status, smoking status, passive smoking, occupation, alcohol consumption, etc. Each 10mg/m(3) increase in PM10 concentrations was associated with a 3.4%-6.0% increase in lung cancer mortality in the time-varying exposure model and a 4.0%-13.6% increase in the baseline exposure model. In multi-pollutant models, the magnitude of associations was attenuated, most strongly for PM10. The association was different in men and women, also varying across age categories and different smoking status. Substantial differences exist in the risk estimates for participants based on assignment method for air pollution exposure.

[Carbon source apportionment of PM2.5 in Chongqing based on local carbon profiles].

PM2.5 was sampled from commercial, industrial and residential areas in Chongqing urban city from 2nd May to 10th May 2012 in order to find out characteristics and sources of carbon in PM2.5. Eight kinds of carbons were analyzed by the TOR method. Characteristics of carbon pollution in PM2.5 from three kinds of functional areas and six kinds of sources, including coal-combustion, exhausts (vehicle, boat and construction machine), biomass burning, cooking smoke, were analyzed. Based on carbon source profiles, local indicating components of carbon sources in PM2.5 were obtained used the chemical mass balance (CMB) model. Contribution rate of different sources to PM2.5 carbon were parsed out by factor analysis. The results showed the OC/EC of coal-combustion, vehicle exhausts, boat exhausts, construction machine exhausts, biomass burning and cooking smoke were 6.3, 3.0, 1.9, 1.4, 12.7 and 31.3, respectively. High loads of EC2 and EC3 indicated diesel vehicle exhaust emissions, high loads of OC2, OC3, OC4 and OPC indicated coal-combustion emissions, OC1, OC2, OC3, OC4 and EC1 indicated gasoline vehicle exhaust emissions, OC3 indicated cooking emissions, and OPC indicated biomass burning emissions. OC/PM2.5, EC/PM2.5, secondary organic carbon (SOC)/OC in the commercial area were 17.4%, 6.9% and 40.0%, respectively. OC/PM2.5, EC/PM2.5 and SOC/OC in the industrial area were 15.5%, 6.6% and 37.4%, respectively. OC/PM2.5, EC/PM2.5 and SOC/OC in the residential area were 14.6% 5.6% and 42.8%, respectively. In the industrial area, the main sources of carbon in PM2.5 were coal combustion, gasoline vehicle exhausts and diesel exhaust. In the commercial area, the main sources of carbon were gasoline vehicle exhausts, diesel exhausts and cooking. In the residential area, the main sources of carbon were gasoline vehicle exhausts, cooking smoke and diesel exhausts.

Long-term exposure to high particulate matter pollution and cardiovascular mortality: a 12-year cohort study in four cities in northern China.

Epidemiologic studies have demonstrated that long-term exposure to relatively low levels of particulate air pollution is associated with adverse cardiovascular outcomes in Europe and North America. However, few studies have assessed the association with high level air pollutants. We aimed to assess the cardiovascular effects of long-term exposure to high level concentrations of inhalable particulate and to identify the characteristics of the Chinese population that are susceptible to the health effects. A retrospective cohort, containing 39,054 subjects from four cities in northern China, was followed for mortality of all cause and specific cardiovascular diseases from 1998 to 2009. Information on concentrations of PM10 (particulate matter<10 µm in aerodynamic diameter) was collected from the local Environmental Monitoring Centers. The estimated exposure for the study participants was the mean concentration of PM10 over their surviving years during the cohort period. Relative risk values were obtained using Cox proportional hazards regression models after adjusting for potential confounding factors. For each 10 µg/m(3) increase in PM10, the relative risk ratios (RRs) of all-cause mortality, cardiovascular disease mortality, ischemic heart disease mortality, heart failure disease mortality, and cerebrovascular disease mortality were 1.24 (95% CI, 1.22-1.27), 1.23 (95% CI, 1.19-1.26), 1.37 (95% CI, 1.28-1.47), 1.11(95% CI, 1.05-1.17), and 1.23(95% CI:1.18-1.28), respectively. Results from stratified analyses suggest that the effects of PM10 on cardiovascular mortality were more pronounced in males, smokers and people with a higher socioeconomic status. Long-term exposure to PM10 increases mortality from cardiovascular disease, especially from ischemic heart disease and this association seemed to be modified by other factors. Further research that focuses on exploring dose-response relationship and inter-population comparisons is warranted.

Health risk assessment for vehicle inspection workers exposed to airborne polycyclic aromatic hydrocarbons (PAHs) in their work place.

Inhalatory and dermal exposures of on-duty vehicle inspection workers to polycyclic aromatic hydrocarbons (PAHs) in Beijing were investigated from April 18 to May 17, 2011. Exposure levels to particulate PAHs for the vehicle inspection workers at gasoline, bus and diesel lines were found to be 56.07 ng m(-3), 111.72 ng m(-3) and 199.80 ng m(-3), respectively. A probabilistic risk assessment framework was integrated with the toxic equivalence factors (TEFs) and the incremental lifetime cancer risk (ILCR) approaches to quantitatively estimate the exposure risk for vehicle inspection workers of the three work lines. The median values of inhalation risk were estimated to be 3.7 × 10(-7), 5.0 × 10(-7) and 1.37 × 10(-6), respectively, while the median dermal ILCR values were 7.05 × 10(-6), 6.98 × 10(-6) and 1.28 × 10(-5), respectively for gasoline, bus, and diesel inspection workers. Total ILCR was higher than the acceptable risk level of 10(-6), indicating unacceptable potential cancer risk.

[Estimation of the effect derived from wind erosion of soil and dust emission in Tianjin suburbs on the central district based on WEPS model].

Due to the lack of a prediction model for current wind erosion in China and the slow development for such models, this study aims to predict the wind erosion of soil and the dust emission and develop a prediction model for wind erosion in Tianjin by investigating the structure, parameter systems and the relationships among the parameter systems of the prediction models for wind erosion in typical areas, using the U.S. wind erosion prediction system (WEPS) as reference. Based on the remote sensing technique and the test data, a parameter system was established for the prediction model of wind erosion and dust emission, and a model was developed that was suitable for the prediction of wind erosion and dust emission in Tianjin. Tianjin was divided into 11 080 blocks with a resolution of 1 x 1 km2, among which 7 778 dust emitting blocks were selected. The parameters of the blocks were localized, including longitude, latitude, elevation and direction, etc.. The database files of blocks were localized, including wind file, climate file, soil file and management file. The weps. run file was edited. Based on Microsoft Visualstudio 2008, secondary development was done using C + + language, and the dust fluxes of 7 778 blocks were estimated, including creep and saltation fluxes, suspension fluxes and PM10 fluxes. Based on the parameters of wind tunnel experiments in Inner Mongolia, the soil measurement data and climate data in suburbs of Tianjin, the wind erosion module, wind erosion fluxes, dust emission release modulus and dust release fluxes were calculated for the four seasons and the whole year in suburbs of Tianjin. In 2009, the total creep and saltation fluxes, suspension fluxes and PM10 fluxes in the suburbs of Tianjin were 2.54 x 10(6) t, 1.25 x 10(7) t and 9.04 x 10(5) t, respectively, among which, the parts pointing to the central district were 5.61 x 10(5) t, 2.89 x 10(6) t and 2.03 x 10(5) t, respectively.

The overall reaction process of ozone with methacrolein and isoprene in the condensed phase.

The reaction of isoprene and methacrolein with ozone was investigated at different stages in the condensed phase at temperatures from 15 to 265 K by IR spectroscopy. The results revealed the following overall reaction process: the generation of primary ozonide (POZ), then its decomposition, and finally conversion into secondary ozonide (SOZ), which supported the Criegee mechanism. In the POZ and SOZ of isoprene, ozone cyclo-added preferentially to the double-bond that is not substituted by the methyl group. For methacrolein, the mainly detected SOZ is claimed to be MACSII formed by recombination of the intermediate CH(2)OO radical with aldehyde carbonyl of methylglyoxal in stead of the ketone carbonyl group. Theoretical calculations were performed at the B3LYP//MP2/6-311++G (2d, 2p) level to analyze the resulting spectrum. The good agreement between the calculated infrared spectra of POZ and SOZ and the experimental spectra supports the above-described findings.

[Estimation of the effect derived from Tianjin suburban wind erosion open source on central district].

In some Chinese cities air pollution is serious, and the major pollutant is still PM10. The source apportionment results show: wind erosion dust is an important source of particulate matter. So the contribution of this source should be calculated. The suburban land of Tianjin was classified based on Landsat TM satellite image, and samples of different land use types were taken. The soil textures were determined with the analysis of soil samples by the laser particle analyzer and GIS-based interpolation computation. The wind erosion modulus, wind erosion fluxes, dust release modulus and dust release fluxes were calculated in four seasons in suburban of Tianjin (Beichen, Xiqing, Jinnan and Dongli). The wind erosion fluxes in spring, summer, autumn and winter were 21236.31, 4435.21, 7272.13 and 17204.4 t in 2009; the wind erosion fluxes in Beichen, Xiqing, Jinnan and Dongli were 6380.23, 32 881.13, 8 340.67 and 2 546.02 t in 2009; the wind erosion fluxes from cultivated land and forest grassland were 49 599.2 and 548.85 t, respectively. The soil dust release fluxes in Tianjin suburban were 9 352.92 t (particle size < 10 microm), 20 587.99 t (particle size 10-15 microm)and 13 873.74 t (particle size 15-20 microm). In 2009, there were 20 592.91 t soil dusts with particulate diameter of 20 microm or less that were transmitted from suburban to central district, and 4 395.89 t with particulate diameter of 10 microm or less, about 21.35%.

[Characterization of atmospheric volatile organic compounds in Shenyang, China].

From April, 2008 to July, 2009, 187 atmospheric samples in four different seasons were collected from five sites in Shenyang. The 108 species of VOCs were measured by using the method of pre-concentration-GC-MS. The objectives of this study were to investigate the VOCs pollution level as well as its spatial and temporal distribution, and to identify the main source in Shenyang city. The results showed that the average total mass concentration of VOCs in Shenyang was 371.0 +/- 132.4 microg/m3. The major components were oxygen-containing compounds, halogenated hydrocarbon, alkanes, aromatics and alkenes, which accounted for 57.2%, 20%, 11.4%, 8.5%, and 3.0% of the total mass, respectively. A seasonal variation of VOCs across all the sampling sites was observed, with higher levels in spring and autumn and lower levels in winter and summer. Related with industrial emission, the diurnal variation of the total mean VOCs concentrations at downtown site showed three peaks in winter and two peaks in summer. The VOCs levels in the industrial and downtown areas were higher than those in other areas, with the lowest concentration observed at clean air site with no emission source around. From the results of correlation analysis and concentration ratios analysis, the VOCs pollutants in Shenyang were mainly contributed by automobile exhaust, coal & biofuel combustion, gasoline & solvent evaporation and industrial process.

Long-term (1996-2006) variation of nitrogen and phosphorus and their spatial distributions in Tianjin coastal seawater.

The spatio-temporal varying characteristics of dissolved inorganic nitrogen, reactive phosphate (RP), chemical oxygen demand (COD), and dissolving oxygen (DO) in Tianjin coastal seawater were investigated based on observation from May 1996 to October 2006. The concentrations of dissolved inorganic nitrogen (DIN), RP and COD ascended gradually and their varying ranges were 0.103-2.432, 0.009-0.12, and 0.8-2.9 mg L(-1), respectively. While DO in seawater decreased from 8.9 to 6.1 mg L(-1) gradually. Those indicated that human-induced eutrophication occurred and the seawater quality deteriorated. The spatial distributions of DIN, RP and COD were largely uniform, where isopleths generally descended from estuarine zones and bays to the central areas and from northern area to southern area, indicating that continental input is the dominant source of those pollutants. Especially, peak zones of those pollutants usually appeared near estuaries, Tianjin harbors, and dumping site of dredged sediment, which indicates that the urban and industrial sewage, shipping waste, dredged soil were the main sources for those contaminants in seawater.

[Effect of 2, 3, 7, 8-tetrachlorodibenzo-p-dioxin on the expression of AhR and TGF-alpha].

OBJECTIVE: To study HaCaT-keratinocyte cell lines, a chosen model of human epidermis in an attempt to analyze the mRNA expression of AhR and TGF-alpha induced by TCDD METHODS: Semi-quantitative reverse transcription PCR-technique was used for assaying the relative levels of AhR and TGF-alpha mRNA of HaCaT-cells during the proliferation period when the cells were cultured for 24 hours. RESULTS: Relative level of the AhR-transcripts (corrected with beta-actin) decreased with the elevated concentration of TCDD and the relevant coefficient between the proliferation rate and concentration was -0.548, and the differences among all groups were significant (F =4.124, P =0.021). The vehicle control was respectively compared with 7 x 10(-10) mol/L (0.0620 +/- 0.0085) and 7 x 10(-9) mol/L (0.0518 +/- 0.0194) group, significantly different from the control group (0.1138 +/- 0.0227) (t = -3.48, P <0.05; t = -4.17, P <0.01), the expression amount being 55% and 45% of the control. Relative levels of TGF-alpha mRNA tended to increase with the elevated concentration with the significant coefficient of 0.695 (P < 0.01), and the differences among all groups were significant (F = 15.789, P =0.000). In two higher concentration group 7 x 10(-10) mol/L (0.1474 +/- 0.0390) and 7 x 10 (-9) mol/L (0.2133 +/- 0.0364), their relative expression amount of TGF-alpha mRNA was 2.6-fold, 3.8-fold of the control group (0.0561 +/- 0.0100) respectively. Further analysis for the relevant relationship between the amounts of the AhR mRNA and TGF- alpha mRNA showed a highly negative correlation, the coefficient being - 0.561 (P <0.05). CONCLUSIONS: TCDD down-regulate the expression of AhR and up-regulate the expression of TGF-alpha. A strong negative correlation between AhR and TGF-alpha expression is found.

Expression of AhR, CYP1A1, GSTA1, c-fos and TGF-alpha in skin lesions from dioxin-exposed humans with chloracne.

Occupational exposure to certain polychlorinated aromatic hydrocarbons such as dioxins has been suggested to cause chloracne which is a kind of skin disease. The molecular mechanisms of dioxin-mediated chloracne have not been clarified. It is possible that dioxins contribute to the pathogenesis through activation of aryl-hydrocarbon receptor (AhR)-mediated transcription and downstream genes such as CYP1A1, GSTA1 and TGF-alpha. The study on genes was through chloracne lesional skin, which has rarely been reported on previously. The expression levels of key genes, such as AhR, CYP1A1, GSTA1, c-fos and TGF-alpha in human epidermal tissue of chloracne cases and controls were detected by real-time PCR. Compared with controls, AhR, CYP1A1, GSTA1 and c-fos transactivations were significantly induced in the skins of chloracne patients who had long-term exposure to dioxins and dibenzofuranes. The TGF-alpha mRNA content of epidermal tissue was increased, but not significantly compared with controls. The study demonstrates that constitutive activation of the AhR pathway is probably a prerequisite of chloracne pathogenesis. The changes of genes expression may disturb normal proliferation and differentiation of human epidermis cells, and then lead to chloracne.