Urban Area Of Guangzhou Research Articles

Characteristics and Source Apportionment of Volatile Organic Compounds in the Rainy Season of Guangzhou City

Atmospheric volatile organic compounds (VOCs) were measured in an urban area of Guangzhou on July 2016 using an on-line gas chromatography mass spectrometry/fire ion detector. Seventy-three VOCs were detected with an average concentration of (118.83±79.40) μg·m-3, a maximum concentration of 492.42 μg·m-3, and a minimum concentration of 10.54 μg·m-3 during the period. The peak value of the TVOC concentration appeared at about 07:00 in the morning, indicating that motor vehicle pollution had a significant contribution at the site. The minimum value appeared at about 14:00 in the afternoon, related to photochemical losses. High concentrations were also observed from 21:00 to 24:00, which was probably related to pollution emissions and boundary layer compression. Source analysis by PMF showed that the site was mainly affected by five VOC sources: vehicle exhaust, solvent use, fuel loss at fuel stations, plant emissions, and cooking exhaust, the contributions of which were 29.79%, 26.61%, 24.86%, 9.91%, and 8.84%, respectively. Vehicle exhaust was the largest source of VOCs during the daytime, while the contribution of plant emissions increased significantly at noon. The contribution of solvent uses and fuel loss at fuel stations rose during the night and became the main source of VOCs until early morning.

Analysis on the non-tuberculosis mycobacteria isolated from the cases with tuberculosis suspicious symptoms domiciling in Yuexiu and Haizhu District of Guangzhou from 2012 to 2016

Objective To understand the prevalence of non-tuberculosis mycobacteria (NTM) in old urban areas of Guangzhou. Methods The information of NTM isolated from the cases with tuberculosis suspicious symptoms domiciling in Yuexiu and Haizhu District of Guangzhou from 2012 to 2016, based on the data of the mycobacteria cultured from laboratory of Tuberculosis Prevention and Control Institute of Yuexiu District in Guangzhou, was collected and analyzed according to year, gender, age-group (≤44, 45-65, and ≥65 years old), and seasons retrospectively. And the difference between groups was compared by χ2 test. Results (1) 1 689 strains of NTM were isolated from 40 418 samples, and the rate was 4.18%. The isolated rates from 2012 to 2016 were 4.05%, 4.58%, 3.24%, 4.67%, and 4.28% respectively, and that in 2014 was significantly lower compared with other years. There was statistically significantly difference in the isolated rate between male and female (3.64% vs.5.18%; P=0.000). The isolated rates of three age-groups were 2.85%, 5.16%, and 7.37% respectively, with statistically significantly differences between age groups (P=0.000). The isolated rates from spring to winter were 3.39%, 4.72%, 4.66%, and 4.00% respectively, with statistically significantly differences of the pairwise comparisons except for summer vs.autumn (all P<0.05). (2) In 716 identified NTM strains, the top 5 species were M.chelonae-abscessus (304 strains), M.avium complex (172 strains), M.kansasii (99 strains), M.gordonae (74 strains), and M.fortuitum (51 strains) respectively. Conclusion The prevalence of NTM in old urban districts in Guangzhou are led by M.chelonae-abscessus, M.avium complex, M.kansasii, M.gordonae, and M.fortuitum, which is mainly affected by gender, age, and season. Key words: Non-tuberculosis mycobacteria; Epidemic characteristics; Mycobacterial culture; Guangzhou

Prevalence of mild cognitive impairment and its subtypes in community-dwelling residents aged 65 years or older in Guangzhou, China

BackgroundPrevalence of mild cognitive impairment (MCI) has been reported substantial variations, and mostly in Western countries. Less is known about MCI in the south of China. The study is to estimate the prevalence of MCI and its subtypes in residents aged 65year or older in community-dwelling residents of Guangzhou, China. MethodsThe study was a community-based, cross-sectional study conducted in rural and urban areas of Guangzhou between April and October 2009. Eight communities were randomly selected using a cluster sampling method. Each elderly was interviewed with Montreal Cognitive Assessment, the Mini-Mental state examination, Auditory Verbal Learning Test, the Clinical Dementia Rating scale et al. MCI was classified as amnestic MCI (a-MCI) or nonamnestic MCI (na-MCI). Results2427 individuals were contacted, but in-person interviews were conducted with 2111 participants. 299 participants with MCI were identified. The prevalence of MCI, a-MCI and na-MCI was 14.2%, 12.2%, 2.0% respectively. The prevalence of MCI and a-MCI increased with age, decreased with education level, and was higher in rural areas than in urban areas. The difference of prevalence of MCI and a-MCI between women with men wasn't statistically significant(MCIχ2=1.0, OR 0.9, 95%CI=0.6-1.2; a-MCIχ2=1.0, OR 0.9, 95%CI=0.6–1.2), when controlling for education by logistic regression analysis. ConclusionsThe results suggest that 14.2% of elderly individuals are affected by MCI in Guangzhou, China. And MCI was dominated by a-MCI. The prevalence of MCI and a-MCI increased with age, decreased with education level, and was higher in the rural population compared to the urban population.

Chemical characterization and sources of personal exposure to fine particulate matter (PM2.5) in the megacity of Guangzhou, China

Concurrent ambient and personal measurements of fine particulate matter (PM2.5) were conducted in eight districts of Guangzhou during the winter of 2011. Personal-to-ambient (P-C) relationships of PM2.5 chemical components were determined and sources of personal PM2.5 exposures were evaluated using principal component analysis and a mixed-effects model. Water-soluble inorganic ions (e.g., SO42-, NO3−, NH4+, C2O42-) and anhydrosugars (e.g., levoglucosan, mannosan) exhibited median personal-to-ambient (P/C) ratios < 1 accompanied by strong P-C correlations, indicating that these constituents in personal PM2.5 were significantly affected by ambient sources. Conversely, elemental carbon (EC) and calcium (Ca2+) showed median P/C ratios greater than unity, illustrating significant impact of local traffic, indoor sources, and/or personal activities on individual's exposure. SO42- displayed very low coefficient of divergence (COD) values coupled with strong P-C correlations, implying a uniform distribution of SO42- in the urban area of Guangzhou. EC, Ca2+, and levoglucosan were otherwise heterogeneously distributed across individuals in different districts. Regional air pollution (50.4 ± 0.9%), traffic-related particles (8.6 ± 0.7%), dust-related particles (5.8 ± 0.7%), and biomass burning emissions (2.0 ± 0.2%) were moderate to high positive sources of personal PM2.5 exposure in Guangzhou. The observed positive and significant contribution of Ca2+ to personal PM2.5 exposure, highlighting indoor sources and/or personal activities, were driving factors determining personal exposure to dust-related particles. Considerable discrepancies (COD values ranging from 0.42 to 0.50) were shown between ambient concentrations and personal exposures, indicating caution should be taken when using ambient concentrations as proxies for personal exposures in epidemiological studies.

Commuting mode specific exposure to PM(2.5) in urban area of Guangzhou

Objective: To find the differences in PM(2.5) exposure level in the context of four commuting modes (by walk, bicycle, bus and subway) in Guangzhou. Methods: The PM(2.5) exposure assessment was carried out from January to December 2015 in Guangzhou. PM(2.5) was measured by using SidePak individual dust meter (AM510, TSI Inc. USA) with time interval of 1 minute. Our measurement was taken on Monday, Wednesday, Friday and Sunday in the second week of each month and the samples were collected in the morning (07:00-09:00), afternoon (11:00-13:00) and evening (17:00-19:00). Results: A total of 284 air samples during walking, 281 air samples during bicycle riding, 278 air samples in bus, and 280 air samples in subway were collected. The median PM(2.5) concentrations exposed during walking, during bicycle riding, in bus and in subway were 38.4, 38.6, 23.3 and 24.1 μg/m(3), respectively, which were positive correlated with exposure concentration in fixed surveillance sites. The exposure level was lowest in summer, and highest in winter. The median of one-way exposure level to PM(2.5) from high to low were as follows: 21.0 μg for bicycle riding, 20.1 μg for walking, 5.1 μg for taking bus and 2.6 μg for taking subway. The season and time specific one-way exposure levels to PM(2.5) of four commuting modes were consistent. Conclusions: The exposure level to PM(2.5) was obviously higher during walking and bicycle riding than that in bus and subway. The exposure level to PM(2.5) during walking was higher than that during bicycle riding, in bus and in subway.

Coupling Modified Linear Spectral Mixture Analysis and Soil Conservation Service Curve Number (SCS-CN) Models to Simulate Surface Runoff: Application to the Main Urban Area of Guangzhou, China

Land surface characteristics, including soil type, terrain slope, and antecedent soil moisture, have significant impacts on surface runoff during heavy precipitation in highly urbanized areas. In this study, a Linear Spectral Mixture Analysis (LSMA) method is modified to extract high-precision impervious surface, vegetation, and soil fractions. In the modified LSMA method, the representative endmembers are first selected by combining a high-resolution image from Google Earth; the unmixing results of the LSMA are then post-processed to reduce errors of misclassification with Normalized Difference Built-up Index (NDBI) and Normalized Difference Vegetation Index (NDVI). The modified LSMA is applied to the Landsat 8 Operational Land Imager (OLI) image from 18 October 2015 of the main urban area of Guangzhou city. The experimental result indicates that the modified LSMA shows improved extraction performance compared with the conventional LSMA, as it can significantly reduce the bias and root-mean-square error (RMSE). The improved impervious surface, vegetation, and soil fractions are used to calculate the composite curve number (CN) for each pixel according to the Soil Conservation Service curve number (SCS-CN) model. The composite CN is then adjusted with regional data of the terrain slope and total 5-day antecedent precipitation. Finally, the surface runoff is simulated with the SCS-CN model by combining the adjusted CN and real precipitation data at 1 p.m., 4 May 2015.

Characterization of PM2.5 in Guangzhou, China: uses of organic markers for supporting source apportionment

Organic carbon (OC), elemental carbon (EC), and non-polar organic compounds including n-alkanes (n-C14-n-C40), polycyclic aromatic hydrocarbons (PAHs), phthalate esters (PAEs) and hopanes were quantified in fine particulate (PM2.5), which were collected in urban area of Guangzhou, China in winter and summer in 2012/2013. The pollutants levels were well comparable with the data obtained in previous studies in Pearl River Delta (PRD) region but much lower than most northern Chinese megacities. The contribution of EC to PM2.5 and OC/EC ratio suggest that the pollution sources were relatively consistent in GZ between the two seasons. Benzo[a]pyrene (BaP) was the most abundant PAHs, which were 4.9 and 1.0ng/m3 on average, accounting for 10.7% and 9.1% to the total quantified PAHs in winter and summer, respectively. The total concentrations of PAEs ranged from 289.1 to 2435ng/m3 and from 102.4 to 1437ng/m3, respectively, in winter and summer. Di-n-butyl phthalate (DBP) was the most dominant PAEs. The ambient levels of PAEs could be partly attributed to the widespread uses of the household products, municipal garbage compressing, sewage, and external painting material on the building. Source apportionment for OC with chemical mass balance (CMB) model demonstrated coal combustion, vehicle emission, cooking, and secondary organic compounds (SOC) formation were the four major pollution sources. Both of the indices of n-alkanes and diagnostic PAHs ratios support that anthropogenic sources such as vehicle emission and coal combustion were the significant pollution sources with some extents from epicuticular waxes by terrestrial plants. The ratio of hopanes to EC proved the influences from vehicle emission, and displayed a certain degree of the air aging in the Guangzhou ambient air.

Cool Roofs in Guangzhou, China: Outdoor Air Temperature Reductions during Heat Waves and Typical Summer Conditions.

In this paper, we simulate temperature reductions during heat-wave events and during typical summer conditions from the installation of highly reflective "cool" roofs in the Chinese megacity of Guangzhou. We simulate temperature reductions during six of the strongest historical heat-wave events over the past decade, finding average urban midday temperature reductions of 1.2 °C. In comparison, we simulate 25 typical summer weeks between 2004 and 2008, finding average urban midday temperature reductions of 0.8 °C, indicating that air temperature sensitivity to urban albedo in Guangzhou varies with meteorological conditions. We find that roughly three-fourths of the variance in air temperature reductions across all episodes can be accounted for by a linear regression, including only three basic properties related to the meteorological conditions: mean daytime temperature, humidity, and ventilation to the greater Guangzhou urban area. While these results highlight the potential for cool roofs to mitigate peak temperatures during heat waves, the temperature reductions reported here are based on the upper bound case, which increases albedos of all roofs (but does not modify road albedo or wall albedo).

Time trends of the incidence of thyroid cancer in urban Guangzhou, 2000-2011

To investigate the incidence and trends of thyroid cancer in urban areas of Guangzhou, 2000-2011. Total of 2 957 new cases with a coverage population of 45 699 522 person-years diagnosed as thyroid cancer in 2000-2011 in urban areas of Guangzhou were extracted from the population-based data base of Guangzhou cancer registry, among which 649 were males and 2 308 were females with a coverage population of 23 391 743 person-years and 22 307 779 person-years, respectively. The crude incidence, Chinese age-adjusted incidence rate and world age-adjusted incidence rate were calculated. Time trends of different gender and age groups were examined using Joinpoint Regression Program. There were a total of 2 957 cases diagnosed as thyroid cancer during 2000-2011 with a sex ratio of 1: 3.56. World age adjusted incidence rates of thyroid cancer in urban areas of Guangzhou increased dramatically from 2.99/100 000 in 2000 to 9.13/100 000 in 2011 with an increase rate of 204.73%. Annual percentage change (APC) was 10.5% (P < 0.001). The APC in world age adjusted incidence rates of thyroid cancer were 8.6% (P < 0.001) for male and 10.9% (P < 0.001) for female, resulting in a total increase of 169.45% (from 1.32/100 000 to 3.54/100 000) for male and 214.64% for female (from 4.73/100 000 to 14.87/100 000). The mean age of onset of thyroid cancer was significantly different between the males and females. The incidence rate of thyroid cancer in females aged 45-59 group (19.56/100 000) reached the highest one.While in males, it was increasing gradually with the age, the incidence increased from 0.74/100 000 in aged 15-19 to 9.48/10 000 in aged of 85 years above. The APC was significant in 20-59 age groups in both males (12.2%) and females (13.4%) (P < 0.001). The incidence rate of thyroid cancer increased rapidly in urban areas of Guangzhou. The prevention and treatment of thyroid cancer should be focused on 20-59 age groups.

An alternative method for estimating hygroscopic growth factor of aerosol light-scattering coefficient: a case study in an urban area of Guangzhou, South China

Abstract. A method was developed to estimate hygroscopic growth factor (f(RH)) of aerosol light-scattering coefficient (bsp), making use of the measured size- and chemically resolved aerosol samples. In this method, chemical composition of the measured aerosol samples were first reconstructed using the equilibrium model ISORROPIA II. The reconstructed chemical composition, which varies with relative humidity (RH), was then employed to calculate bsp and hygroscopic growth factor of bsp (fsp(RH)) using the Mie model. Furthermore, the calculated fsp(RH) was fitted with an empirical curve. To evaluate the applicability of fsp(RH), the curve of fsp(RH) was used to correct the long-term records of the measured bsp from the values under comparative dry conditions to the ones under ambient RH conditions. Compared with the original bsp data, the fsp(RH)-corrected bsp had a higher linear correlation with, and a smaller discrepancy from, the bsp derived directly from visibility and absorption measurements. The fsp(RH) determined here was further compared with that reported in previous studies. The method described in this manuscript provides an alternative approach to derive credible fsp(RH) with high accuracy and has many potential applications in aerosol-related research.

Risk assessment of arsenic and other metals via atmospheric particles, and effects of atmospheric exposure and other demographic factors on their accumulations in human scalp hair in urban area of Guangzhou, China

Eighty-eight scalp hair samples were collected from Guangzhou (GZ) urban population (15–65 years) to investigate the accumulation of As and other metals (Cr, Mn, Ni, Cu, Zn, Cd, Sn, Sb, Hg and Pb). Demographic information, including body weight, height, age, gender, habits of smoking and drinking, types of drinking water, duration of stay in GZ, days of stay in GZ per year (days/year), and hours spent in indoor environment per day (h/day), were also recorded during hair sampling to refine the uncertainty of risk assessment derived from exposures to elements via dust and airborne particles. No significant non-carcinogenic risk was found. However, the cancer risks of Cr and As for both ingestion and inhalation exceeded the most tolerable regulated level (1.0×10−6). The environmental exposures to urban dust and airborne particles were observed significantly correlated to accumulations of Cd (R=0.306, p=0.005) and Ni (R=0.333, p=0.002) in scalp hair. Furthermore, the hair burden of elements was also significantly (p<0.05) dependent on gender (Mn, Ni, Zn, As, Sn and Hg), age (Cr, As, Cd and Hg), duration of stay in GZ (Hg) as well as nutritional and physical status, reflected by BMI and BSA (Cr, Ni, Cd, Sb and Hg). Nutritional and physical status was observed as the exclusive important factor influencing As speciation in human scalp hair. However, habits of smoking and alcohol drinking as well as types of drinking water were not identified as the significant influencing factors on any element (p>0.05).

Significance of wet deposition to removal of atmospheric particulate matter and polycyclic aromatic hydrocarbons: A case study in Guangzhou, China

Rainwater samples were simultaneously collected from three locations in Guangzhou, a mega metropolitan center in South China, during the entire year of 2010, and analyzed for particulate matter (PM), total organic carbon and polycyclic aromatic hydrocarbons (PAHs), with the objectives of assessing the seasonality of washout effects and efficiency for removal of pollutants from the atmosphere by wet deposition. The contents of PM, particulate organic carbon, and dissolved organic carbon were in the ranges of 0.74–420 (average: 8.1 mg L−1), 0.16–40 (average: 1.3 mg L−1), and 0.34–6.9 mg L−1 (average: 1.4 mg L−1), respectively. Concentrations of Σ15PAH (sum of the 16 priority PAH compounds defined by the United States Environmental Protection Agency minus naphthalene) in wet deposition samples ranged from 39 to 1580 ng L−1 with an average of 170 ng L−1. The PAH concentration levels were slightly abated compared to those acquired previously in Guangzhou during the year of 2005, probably indicating a favorable change of energy consumption patterns in the region. There were moderately significant negative correlations between washout ratios and rainfall intensities (0–4.3 mm h−1). The total annual fluxes of wet and dry depositions combined for PM and PAHs in the urban area of Guangzhou were 34 g m−2 yr−1 and 6.0 × 102 μg m−2 yr−1 with 50 and 57% being contributed from wet deposition, respectively. The monthly capacity for removal (CR) of PM and PAHs (calculated as the wet deposition flux dividing the total flux) varied widely with different months, and was lower during the dry weather season (January–March and October–December) than during the wet weather season (April–September). Finally, the air quality index related to PM10 was negatively correlated to CR values of PM and PAHs, indicating the need to control the emissions of anthropogenically derived pollutants during the dry weather season.

Characteristics and influencing factors of mercury exchange flux between soil and air in Guangzhou City

This study aimed to characterize atmospheric mercury (Hg) as well as the Hg exchange flux between soil and air surfaces in the urban area of Guangzhou. Total gaseous Hg (TGM) concentration and Hg exchange flux were measured in situ using a dynamic flux chamber coupled with a Mercury Vapor Analyzer. The TGM averaged 6.3±2.2ng·m−3 at five sites, and average Hg exchange flux was 7.8±7.1ng·m−2·h−1. Both Hg content and soil pH were significantly correlated with Hg fluxes, suggesting that soil properties affected Hg exchanges. The Hg exchange fluxes showed significantly positive correlations with solar radiation and soil temperature. Comparisons demonstrated that vegetation significantly interfered with the Hg emission flux. The annual Hg emission from soil in Guangzhou urban area was 51.46g·km−2·yr−1 or 25.73kg·yr−1.

Impact of relative humidity and particles number size distribution on aerosol light extinction in the urban area of Guangzhou

Abstract. In the urban area of Guangzhou, observations on aerosol light extinction effect were conducted at a monitoring site of the South China Institute of Environmental Sciences (SCIES) during April 2009, July 2009, October 2009 and January 2010. The main goal of these observations is to recognise the impact of relative humidity (RH) and particles number distribution on aerosol light extinction. PM2.5 was sampled by Model PQ200 air sampler; ions and OC/EC in PM2.5 were identified by the Dionex ion chromatography and the DRI model 2001 carbon analyser, respectively; particles number size distribution was measured by TSI 3321 APS, while total light scattering coefficient was measured by TSI 3563 Nephelometer. Chemical composition of PM2.5 was reconstructed by the model ISORROPIA II. As a result, possible major components in PM2.5 were (NH4)2SO4, Na2SO4, K2SO4, NH4NO3, HNO3, water, POM and EC. Regarding ambient RH, mass concentration of PM2.5 ranged from 26.1 to 279.1 μg m−3 and had an average of 94.8, 44.6, 95.4 and 130.8 μg m−3 in April, July, October and January, respectively. With regard to the total mass of PM2.5, inorganic species, water, POM, EC and the Residual accounted for 34–47%, 19–31%, 14–20%, 6–8% and 8–17%, respectively. Under the assumption of "internal mixture", optical properties of PM0.5–20 were estimated following the Mie Model. Optical refractive index, hygroscopic growth factor and the dry aerosol density required by the Mie Model were determined with an understanding of chemical composition of PM2.5. With these three parameters and the validated particles number size distribution of PM0.5–20, the temporal variation trend of optical property of PM0.5–20 was estimated with good accuracy. The highest average of bep,pm0.5–20 was 300 Mm−1 in April while the lowest one was 78.6 Mm−1 in July. Regarding size distribution of bep,pm0.5–20, peak value was almost located in the diameter range between 0.5 and 1.0 μm. Furthermore, hygroscopic growth of optical properties of PM0.5–20 largely depended on RH. As RH increased, bep,pm0.5–20 grew and favoured a more rapid growth when aerosol had a high content of inorganic water-soluble salts. Averagely, fbep,pm0.5–20 enlarged 1.76 times when RH increased from 20% to 90%. With regard to the temporal variation of ambient RH, fbep,pm0.5–20 was 1.29, 1.23, 1.14 and 1.26 on average in April, July, October and January, respectively.

Characteristics of fine particulate non-polar organic compounds in Guangzhou during the 16th Asian Games: Effectiveness of air pollution controls

The concentrations of organic compounds, including n-alkanes and polycyclic aromatic hydrocarbons (PAHs), in fine particles (PM2.5) were measured in an urban area of Guangzhou before, during, and after the 16th Asian Games (9–30 November 2010). Higher average concentrations of n-alkanes and PAHs occurred in the nighttime, presumably due to a restriction on motor vehicle operation during the day and the accumulation of pollutants due to temperature inversions at night. The carbon preference index, contributions of wax n-alkanes, and PAHs diagnostic ratios indicated that the main sources of n-alkanes and PAHs were anthropogenic, especially motor vehicle emissions. The CMAQ model was used to estimate the percentages of biogenic organic aerosol in the total organic aerosol, then the ratios of source marker PAHs to biogenic organic carbon were used to evaluate the air pollution control policies effectiveness during the Asian Games.

Historical evaluation of vehicle emission control in Guangzhou based on a multi-year emission inventory

The Guangzhou government adopted many vehicle emission control policies and strategies during the five-year preparation (2005–2009) to host the 2010 Asian Games. This study established a multi-year emission inventory for vehicles in Guangzhou during 2005–2009 and estimated the uncertainty in total vehicle emissions by taking the assumed uncertainties in fleet-average emission factors and annual mileage into account. In 2009, the estimated total vehicle emissions in Guangzhou were 313 000 (242 000–387 000) tons of CO, 60 900 (54 000–70 200) tons of THC, 65 600 (56 800–74 100) tons of NOx and 2740 (2100–3400) tons of PM10. Vehicle emissions within the urban area of Guangzhou were estimated to be responsible for ∼40% of total gaseous pollutants and ∼25% of total PM10 in the entire city. Although vehicle use intensity increased rapidly in Guangzhou during 2005–2009, vehicle emissions were estimated to have been reduced by 12% for CO, 21% for THC and 20% for PM10 relative to those in 2005. NOx emissions were estimated to have remained almost constant during this period. Compared to the “without control” scenario, 19% (15%–23%) of CO, 20% (18%–23%) of THC, 9% (8%–10%) of NOx and 16% (12%–20%) of PM10 were estimated to have been mitigated from a combination of the implementation of Euro III standards for light-duty vehicles (LDVs) and heavy-duty diesel vehicles and improvement of fuel quality. This study also evaluated several enhanced vehicle emission control actions taken recently. For example, the enhanced I/M program for LDVs was estimated to reduce 11% (9%–14%) of CO, 9% (8%–10%) of THC and 2% (2%–3%) of NOx relative to total vehicle emissions in 2009. Total emission reductions by temporary traffic controls for the Asian Games were estimated equivalent to 9% (7%–11%) of CO, 9% (8%–10%) of THC, 5% (5%–6%) of NOx and 10% (8%–13%) of PM10 estimated total vehicle emissions in 2009. Those controls are essential to further vehicle emission mitigation in Guangzhou required by the new National Ambient Air Quality Standards.

Mercury levels in road dust and household TSP/PM2.5 related to concentrations in hair in Guangzhou, China

Road dust, household total suspended particulate matters (TSP) and PM2.5 were collected in urban area of Guangzhou, south of China, to investigate the concentrations of total mercury (THg) and methyl mercury (MeHg). The household PM2.5 concentrations varied between 16.2 and 623μg/m3. The average PM2.5 level (174μg/m3) from all of the locations exceeded 24-h concentration from WHO air quality guideline The average concentrations of THg and MeHg were: 235μg/kg and 0.392μg/kg in road dust, 600μg/kg and 1.49μg/kg in TSP; 1006μg/kg (104pg/m3) and 1.40μg/kg (0.134pg/m3) in PM2.5. Risk assessment showed that the Hazardous quotients (HQs) of exposure to Hg and MeHg via road dust and TSP were less than 1, indicating that no adverse risk was manifested. Ingestion of dust was found to constitute a relatively minor pathway of Guangzhou residents′ exposure to Hg. Furthermore, human hair samples from 88 Guangzhou citizens were also analyzed to investigate the mercury accumulation in human body in Guangzhou. The average concentrations of THg and MeHg in human hair samples were 869±831μg/kg and 104±108μg/kg respectively. However, no significant correlations of the mercury species were noted between human hair and road dust, TSP and PM2.5.

Seasonal and Diurnal Variations of Atmospheric Non-Methane Hydrocarbons in Guangzhou, China

In recent decades, high ambient ozone concentrations have become one of the major regional air quality issues in the Pearl River Delta (PRD) region. Non-methane hydrocarbons (NMHCs), as key precursors of ozone, were found to be the limiting factor in photochemical ozone formation for large areas in the PRD. For source apportioning of NMHCs as well as ozone pollution control strategies, it is necessary to obtain typical seasonal and diurnal patterns of NMHCs with a large pool of field data. To date, few studies have focused on seasonal and diurnal variations of NMHCs in urban areas of Guangzhou. This study explored the seasonal variations of most hydrocarbons concentrations with autumn maximum and spring minimum in Guangzhou. The diurnal variations of most anthropogenic NMHCs typically showed two-peak pattern with one at 8:00 in the morning and another at 20:00 in the evening, both corresponding to traffic rush hours in Guangzhou, whereas isoprene displayed a different bimodal diurnal curve. Propene, ethene, m, p-xylene and toluene were the four largest contributors to ozone formation in Guangzhou, based on the evaluation of individual NMHCs’ photochemical reactivity. Therefore, an effective strategy for controlling ozone pollution may be achieved by the reduction of vehicle emissions in Guangzhou.

Water quality remediation in a heavily polluted tidal river in Guangzhou, South China

A field-scale experiment was performed to remediate a heavily polluted river located in the urban area of Guangzhou, China using biological and chemical techniques combined with engineering processes. Before comprehensive remediation was undertaken, several small-scale experiments to test river-water remediation techniques were successfully performed. After comprehensive remediation, the average reduction rates of chemical oxygen demand and biochemical oxygen demand and removal rates of other pollutants were all above 70 percent. Furthermore, the unpleasant odor emanating from the polluted river was also greatly reduced. The field-scale experiment thus indicated the feasibility and validity of the method applied to remediate this heavily polluted river; this method can therefore be applied to remediate other heavily polluted rivers in the Guangzhou urban area and elsewhere.

Study on Electricity Consumption for Domestic Refrigerators, Air Conditioners, and Water Dispenser in Guangzhou (China) urban area based on Questionnaire Data

In China, since the 1990's, as household incomes have increased, many kinds of appliances have been purchased, causing the electricity demand to grow from year to year. Widely-used air conditioners and recently penetrated water dispensers, in particular, contribute mainly to increased electricity consumption in the household sector. In this context, we conducted a study to provide descriptive information on the effects of this recent electricity consumption of installed air conditioners, refrigerators, water dispensers, and the standby power of electric devices of urban households in Guangzhou based on the result of our survey in 2004. The result of this study suggests that in terms of water dispensers extending operation time is a serious factor affecting increased electricity consumption. Moreover, replaced air conditioners for power saving may not be enough to reduce the growing electricity consumption.