[HONO Pollution Characteristics and Nighttime Sources During Autumn in Guangzhou, China].

Nitrous acid (HONO) plays an important role in atmospheric photochemistry processes because its photolysis provides an efficient source of hydroxyl (OH) radicals in the troposphere. However, few studies exist on HONO in nocturnal chemistry processes. Using the observation data of HONO and related parameters for a super site at Guangzhou Jinan University in October 2015, the pollution processes and sources of HONO during nighttime were analyzed in this study. The results showed that the average concentration of HONO was 4.32 µg ·m-3 during the nighttime, which was 2.6 times its concentration of 1.67 µg ·m-3 in the daytime. The conversion rate of HONO, CHONO, during the nighttime was 0.0068 h-1, and the average contribution of vehicle emissions to HONO was 15.1%, with a peak of 37.8% at 20:00. The average net HONO generation rate from the reaction of NO and OH radicals during the night was 0.44 µg ·(m3 ·h)-1. Correlation analysis suggested that particles could not be the major HONO source, but that relative humidity (RH; 33%-78%) was a key factor. Relevant calculation indicated that the heterogeneous reaction of deposited NO2 on humid ground surfaces could be the main source of HONO during nighttime.

[Characteristics of Volatile Organic Compounds Emitted from Biomass-pellets-fired Boilers].

A pre-concentrator-GC-MS/FID was used to investigate the characteristics of volatile organic compounds (VOCs) based on the flue gases emitted from five biomass-pellets-fired boilers in this study. And the concentrations of particle matter, nitrogen oxides (NOx), sulfur dioxides (SO2) and mercury and its compounds were also measured. Results demonstrated that the concentrations of SO2 and mercury and its compounds emitted from all five boilers were relatively low, which were lower than the national emission standard, while NOx and particles from some boilers were higher than the standard. The mass concentration of 56 VOC species was in the range of (872.43±293.80)-(6929.66±1137.25) µg·m-3, and the analysis of influencing factors implied that the furnace temperatures and loads havd strong negative correlations with the concentration of total VOCs. The emission components of VOCs were mainly composed of alkenes (41%-59%) including ethylene, 1-butene, cis-2-butene and 1-hexene; alkanes (27%-49%) including hexane, isopentane and cyclopentane; and aromatics (6%-18%) including benzene and toluene. Moreover, the maximum incremental reactivity (MIR) method was applied to analyze ozone formation potential (OFP) of VOCs. The contribution of OFP of five boilers was mainly from alkenes, occupying a relatively high percentage of 76%-90%, and that of alkanes was in the range of 6% to 19%.

[Source profile of volatile carbonyl compounds in wastewater treatment plant of an oil refinery].

An observation was conducted at the wastewater treatment plant in a refinery in Guangdong province, using the PFPH-GC/MS method to analyze the composition and the concentration of volatile carbonyl compounds. The emission characteristics and the atmospheric chemical reactivity of these compounds were also studied. The results showed that 20 kinds of carbonyl compounds were detected with a concentration range of 0 to 68.80 microg x m(-3). The mean value of total concentration in all processing unit was (253.02 +/- 124.5) microg x m(-3). Background corrected concentrations showed that for each of the 6 treatment units of the plant, over 90% of the volatile carbonyl emissions were contributed by 14 of the 20 volatile carbonyl compounds, among which aldehyde was the most abundant with an average concentration of (44.74 +/- 20.89) microg x m(-3), followed by 2-butanone and acetaldehyde with average concentrations of (30.47 +/- 12.94) microg x m(-3) and (23.51 +/- 14.57) microg x m(-3), respectively. Several molecular markers were identified based on the analysis of the chemical activities and atmospheric lifetimes of the 20 carbonyl compounds. Finally, a source profile was established for the plant.

[Study on quantification assessment and odor fingerprint of volatile aromatic hydrocarbons from sewage treatment plant].

The malodorous volatile organic compounds (MVOCs) from a typical municipal sewage treatment plant in Guangzhou were detected and analyzed using thermal-desorption/GC-MS and electronic nose, respectively. The results showed that: (1) Aromatic hydrocarbons were the main malodorous volatile organic compounds of the sewage treatment plant, with concentrations ranging from 96.61 microg x m(-3) to 818.03 microg x m(-3), accounting for more than 50% of the total MVOCs, much higher than other MVOCs species. (2) Volatile aromatic hydrocarbons (VAH) in municipal sewage treatment plant were mainly from domestic wastewater, and the sludge treatment process played an important part in release of these pollutants. The total concentration of aromatic hydrocarbons emitted from each processing unit in a descending order was: the sludge dehydration room > sludge thickener > aeration tank > grille > biochemical pool> grit chamber. (3) rincipal component analysis (PCA) was able to distinguish the characteristic of odor emission from each processing unit, with the recognition index reaching 71% , and the PCA recognition index of simulated gases which simulated the VAH levels of different processes reached 94% , indicating that there was big difference among the srmll of the VAH emitted from different processes. (4) The comparison of the original odor fingerprint and simulated odor fingerprint measured by the sensor T70/2 showed that the original odor fingerprint was greater than the simulated odor fingerprint, and the correlation analysis indicated that the VAH had a great contribution to the odor fingerprint of each unit, and the contribution of VAH odor of the aeration tank tq the original odor fingerprint reached 0. 98.

[Impact of heavy-duty diesel vehicles on air quality and control of their emissions].

Through an analysis of the characteristics of diesel vehicle emissions and motor vehicle emissions inventories, this paper examines the impact of heavy-duty diesel vehicles on air quality in China as well as issues related to the control of their emissions. Heavy-duty diesel vehicles emit large amounts of nitrogen oxides and particulate matter. Nitrogen oxides is one of the important precursors for the formation of secondary particles and ozone in the atmosphere, causing regional haze. Diesel particulate matter is a major toxic air pollutant with adverse effect on human health, and in particular, the ultrafine particles in 30-100 nm size range can pose great health risks because of its extremely small sizes. Motor vehicles have become a major source of air pollution in many metropolitan areas and city cluster in China, and among them the heavy-duty diesel vehicles are a dominant contributor of nitrogen oxides and particulate matter emissions. Hence, controlling heavy-duty diesel vehicle emissions should be a key component of an effective air quality management plan, and a number of issues related to heavy-duty diesel vehicle emissions need to be addressed.

[Characterizing spatial patterns of NO(x), SO2 and O3 in Pearl River Delta by passive sampling].

Concentrations of NO(x), SO2 and O3 were measured by passive sampling within 200km x 200km grid in Pearl River Delta (PRD). Sampling period was two weeks in November, 2009. Spatial distributions of NO(x), SO2 and O3 were obtained by Kriging interpolation method. The results were compared with emission inventories and modeling results. The transportations of O3 were evaluated by using backward trajectories of air parcels. During the sampling period, the mean concentrations of NO(x), SO2 and O3 were 75.9 microg/m3, 37.3 microg/m3 and 36.2 microg/m3, respectively. And the highest concentrations of NO(x), SO2 and O3 were 195.7 microg/m3, 95.9 microg/m3 and 81.8 microg/m3. Comparing with routine measurements from the regional monitoring network in PRD, the results by passive method were 18.6%, 33.5% and 37.5% lower for NO(x), SO2 and O3, respectively. The spatial patterns demonstrated that higher NO(x) concentrations often appeared in cities such as Guangzhou, Foshan and Shenzhen. SO2 concentrations were higher in west and lower in east. High SO2 concentrations are mainly from emission of power plants and industrial sources. Concentrations of O3 showed the highest levels in the south of PRD. Backward trajectory analysis for higher ozone areas indicated that 53% of the air masses were from the region with high concentration of NO(x). The horizontal transportation caused higher ozone in the south while lower in north in PRD.

[Source emission characteristics of malodorous volatile organic carbonyls from a municipal sewage treatment plant].

A 4-day field observation was conducted at Liede sewage treatment plant in Guangzhou, using PFPH/GC/MS method to analyse the composition and the concentration of volatile carbonyl compounds, and investigate the source emission characteristics of the pollutants. The results were as follows: 18 carbonyl species were detected, which including 15 malodorous volatile carbonyls with a concentration range from 0.39 microg x m(-3) to 19.92 microg x m(-3) at six processing units. Mean value of the total malodorous volatile carbonyls was (68.66 +/- 10.05) microg x m(-3). Normalization data process was used to research the source emission profile for malodorous volatile carbonyls, formaldehyde, acetaldehyde, propionaldehyde, 2-butanone, butyraldehyde and hexaldehyde were found to be molecular markers of the source emission with their percentage of total carbonyls up to 78.91%. Hexaldehyde was the most abundant carbonyl species with an average concentration of 11.71 microg x m(-3). Using a calculation model of area source emission, it estimated that the total annual emissions of the municipal sewage treatment plant was 2 302.33 kg(-1), and the contribution ratio of each processing unit was in an order of biochemical reaction basin, concentration basin, grade A aeration, ascending pump room, grit basin, dewatering house. The malodorous emission of sewage treatment plant is affected by many complex factors, so there's some uncertainty on the estimate.

[Source emission characteristics and impact factors of volatile halogenated organic compounds from wastewater treatment plant].

A low enrichment method of using Tenax as absorbent and liquid nitrogen as refrigerant has been established to sample the volatile halogenated organic compounds in Guangzhou Liede municipal wastewater treatment plant as well as its ambient air. The composition and concentration of target halogenated hydrocarbons were analyzed by combined thermal desorption/GC-MS to explore its sources profile and impact factors. The result showed that 19 halogenated organic compounds were detected, including 11 halogenated alkanets, 3 halogenated alkenes, 3 halogenated aromatic hydrocarbons and 2 haloesters, with their total concentrations ranged from 34.91 microg x m(-3) to 127.74 microg x m(-3) and mean concentrations ranged from n.d. to 33.39 microg x m(-3). Main pollutants of the studied plant were CH2Cl2, CHCl3, CFC-12, C2H4Cl2, CFC-11, C2HCl3 and C2Cl4, they came from the wastewater by volatilization. Among the six processing units, the dehydration room showed the highest level of halogenated organic compounds, followed by pumping station, while the sludge thickener was the lowest. The emissions from pumping station, aeration tank and biochemical pool were significantly affected by temperature and humidity of environment.

[Quantification assessment of the relationship between chemical and olfactory concentrations for malodorous volatile organic compounds].

Using self-made cold-traps and gas bags, the odor samples were collected from 6 sewage treatment workshops of a typical municipal sewage treatment plant in Guangzhou City. The chemical composition and olfactory concentrations of these samples were respectively analyzed by thermal-desorption/GC-MS and triangle odor bag method. Finally, a mathematical equation was built for assessing the relationship between principal organic odorants and the olfactory concentrations. The result showing that: (1) More than 70 volatile organic compounds were detected in municipal sewage treatment plant, among which were 30 malodorous volatile organic compounds (MVOCs), ranging from 0.37 to 1 872.24 microg x m(-3) and appearing in sludge dewatering, thickening and aeration tank with the highest concentrations. (2) Principle component analysis was used to group the target MVOCs into 5 categories: benzenes, halohydrocarbons, aldehydes, hydrocarbons and S, N-containing organic compounds. (3) Multiple lineal regression analysis was used to build a quantified relationship between chemical and olfactory concentrations of MVOCs. The result indicated that 25% of the odor problem of sewage treatment unit was due to MVOCs. The predicted values were fitting well with measured values. The sensitivity of mathematical equation for measuring odor concentration was higher than that of human olfactory system.

[Research on source profile of aerosol organic compounds in leather plant].

Through investigating current air pollution condition for PM10 in every factories of different style leather plants in Pearl River Delta, characteristic profile of semi-volatile organic compounds in PM10 emitted from leather factories and their contents were researched by using ultrasonic and gas chromatography and mass spectrum technology. The 6 types of organic compounds containing 46 species in total were found in the collected samples, including phenyl compounds, alcohols, PAHs, acids, esters and amides. The concentrations of PM10 in leather tanning plant, leather dying plant and man-made leather plant were 678.5, 454.5, 498.6 microgm x m(-3) respectively, and concentration of organic compounds in PM10 were 10.04, 6.89, 14.21 microg x m(-3) in sequence. The more important type of pollutants in each leather plants had higher contribution to total organic mass as follows, esters and amides in tanning plants profile account for 43.47% and 36.51% respectively; esters and alcohols in dying plants profiles account for 52.52% and 16.16% respectively; esters and amide in man-made leather plant have the highest content and account for 57.07% and 24.17% respectively. In the aerosol organic source profiles of tested leather plants, 9-octadecenamide was the abundant important species with the weight of 26.15% in tanning plant, and Bis(2-ethylhexyl) phthalate was up to 44.19% in the dying plant, and Bis(2-ethylhexyl) maleate and 1-hydroxy-piperidine had obviously higher weight in man-made plant than the other two plants.

[Character of volatile carbonyl compounds and their source in Guangzhou ambient air].

Characterizations and their primary sources of 17 carbonyls compounds in the serious air polluted summer-days of 2006 were studied by DNPH-HPLC-UV measurement methods. Results were shown as follows, acetone was found to be the most predominant carbonyls followed by formaldehyde, 2-butone and acetaldehyde, with the 24 h average concentrations of 10.84, 9.29, 8.35, 8.0 microg x m(-3) respectively, which accounted for 72.29% of total carbonyl compounds in the atmosphere. Among the four sites, the highest level of total carbonyl compounds was 59.66 microg x m(-3) at the urban site of Guangdong Provincial Centre of Environmental Monitor, the lowest was 43.51 microg x m(-3) at the rural site of Conghua. Different variation characterizations of each carbonyl compounds at there different height sites were found, and the diurnal variation was shown that the total concentration of carbonyl compounds in daytime was much higher than that of nighttime. Good correlations between formaldehyde, acetaldehyde and acetone indicated that they mainly derived from the same sources, and the value that C1/C2 and C2/C3 ratios were 1.12 and 7.51 respectively implied that the important pollution sources of carbonyl compounds was vehicular exhaust in Guangzhou.

[Methyl tert-butyl ether (MTBE) in atmosphere of the Pearl River Delta, China].

The concentration of methyl tert-butyl ether (MTBE) and its spatio-temporal distribution were researched in atmosphere of the Pearl River Delta (PRD) by sampling with air sampling canisters and analyzing with pre-concentrator and gas chromatograph-mass spectrum instrument. The results showed that 1) MTBE could be prevalently checked in atmosphere of traffic area, industrial area, residential area and commercial area of the PRD, and its range of hourly average concentration in the long-term observation was from 0 - 1.250 microg m(-3), the summer had more serious pollution than the spring, and urban was the central area of high MTBE concentration, and suburban in the downwind was obviously polluted by the urban air. 2) During the enhanced observation in summertime, the diurnal average concentration of Guangzhou urban site was (1.520 +/- 0.370) microg m(-3), which was about 7 times of Huadou site in the downwind of Guangzhou and over 100 times of Conghua site in the background of Guangzhou. In urban, 2 peak values appeared in the period of 10:00 - 12:00 and 16:00 - 18:00 respectively, and the nighttime had the lowest average concentration, but the suburban in the downwind had the peak value in the nighttime. 3) During the enhanced observation in wintertime, the diurnal average concentration of Guangzhou urban site was (0.950 +/- 0.240) microg m(-3), which was 3.6 times of Xinken site in the downwind of Guangzhou. Several peak values appeared on the diurnal variation, the high concentration period of urban was in 18:00 - 22:00, and that of suburban was in 04:00 - 10:00 of the next day. 4) When it was weak sunshine, the concentration of MTBE beside the urban traffic roadside was decreasing with the height increasing, but when it was strong sunshine, it was increasing with the height increasing. So, except the original emission from the automobiles, MTBE still had the secondary pollution sources formed by air photochemical reaction.

[Preparation and photocatalytic activity of boron doped CeO2/TiO2 mixed oxides].

Boron doped CeO2/TiO2 mixed oxides photocatalysts were prepared by adding boric acid and cerous nitrate during the hydrolyzation of titanium trichloride and tetrabutyl titanate. XRD, UV-Vis DRS and XPS techniques were used to characterize the crystalline structure, light absorbing ability and the chemical state of Boron element in the photocatalyst sample. The photocatalytic activities were evaluated by monitoring the degradation of acid red B under UV irradiation. These results indicate that the wavelengths at adsorbing edge are affected by the content of cerous nitrate and the maximum absorption wavelength is about 481 nm when the mole ratio of Ce/Ti is 1.0. For higher dosage of Cerium, the absorbance edge shifts to blue slightly. The prepared photocatalyst is composed of anatase TiO2 and cubic CeO2 when calcined at 500 degrees C. An increase in the calcination temperature transforms the crystalline structure of the titanium oxides from anatase to rutile, and has no obvious influence on crystalline structure of CeO2 but crystallites growth up. The absorbance edge decreases drastically with the increase of calcination temperature. With a view to the stability of photocatalyst and utilization of sun energy, 500 degrees C of calcination temperature is recommended. The XP spectrum for B1s exhibits that only a few boron ions dope into titania and ceria matrix, others exist in B2O3. The photocatalytic activity increases with increase of cerous nitrate dosage, and decreases drastically due to higher dosage (the mol ratio of Ce/Ti > 0.5). After 10 min UV irradiation, 96% of acid red B is degraded completely over photocatalyst under optimum reaction condition.

[Preliminary determination of organic pollutants in agricultural fertilizers].

Organic pollutants such as polycyclic aromatic hydrocarbons (PAHs) in agricultural fertilizers are new problem deserved more study. Eight kinds of organic pollutants including 43 compounds classified as US EPA priority pollutants in twenty one agricultural fertilizers which were universally used in China were determined by Gas chromatography-mass spectrum (GC-MS). Three kinds of organic pollutants including more than 5 compounds were detected in most fertilizers, composing mainly of phthalic acid esters (PAEs), nitrobenzenes (NBs) and polycyclic aromatic hydrocarbons (PAHs). There were 26 compounds detected in at least one fertilizer, five of them especially PAEs detected in most fertilizer and even in all fertilizers. Benzo(a)pyrene, a strongly carcinogenic compound was detected in two fertilizers. Higher concentrations of compounds were determined in those fertilizers such as multifunction compound fertilizers and coated fertilizers.