Search

The hourly concentrations of 102 volatile organic compounds (VOCs) in Wuhan from June to July in 2019 were obtained using an online monitoring instrument. The ρ (VOCs) varied from 24.9 to 254 μg·m -3 , with a mean value of (67.7±32.2) μg·m -3 . According to the air quality standard of ozone, the observation period was divided into clean and polluted episodes of O 3 . The differences in meteorological parameters, VOC concentrations, compositions, sources, and ozone formation potential (OFP) between clean and polluted episodes were analyzed and compared. The average mass concentrations of NO x , CO, and VOCs in polluted periods exceeded those of clean periods by 34.9%, 25.0%, and 27.8%, respectively. The mass concentrations of alkanes, alkenes, aromatic hydrocarbons, and oxygenated volatile organic compounds in polluted periods were higher than those in clean periods by 40.7%, 39.5%, 26.9%, and 21.5%, respectively. The average OFP in polluted periods[(102±69.6) μg·m -3 ] exceeded that of clean periods by 33.5%. The average contribution rates of LPG combustion, industrial sources, vehicle emissions, natural sources, and solvent usage to VOCs were 3.4%, 2.5%, 0.2%, 1.3%, and 1.4% lower than those of the clean periods, respectively, whereas the gasoline evaporation increased by 8.8% in polluted periods. The contributions of vehicle emissions and gasoline evaporation exhibited higher values in the morning and evening, with lower values in the afternoon, which may have been related to peak vehicles emissions. The contribution of LPG combustion peaked along with the cooking time. The concentration weighted trajectory showed that the main sources of VOCs in polluted periods were from local emissions and surrounding regions in the northeastern direction of Wuhan. In polluted periods, gasoline evaporation and LPG combustion should be emphasized for preventing O 3 pollution in the summer in Wuhan.

In order to investigate the pollution characteristics and sources of water-soluble ions in atmospheric PM 2.5 in different regions of central China during summer, Wuhan, Suizhou, and Pingdingshan were selected as urban, suburban, and rural monitoring stations, respectively, to collect PM 2.5 samples, and the mass concentration of PM 2.5 in the atmosphere and the contents of eight water-soluble ions were analyzed. The results showed that ρ (water-soluble ions) at the three sites showed obvious spatial distribution characteristics, with Pingdingshan[(36.29±9.82) μg·m -3 ] > Wuhan[(32.55±10.05) μg·m -3 ] > Suizhou[(26.10±6.23) μg·m -3 ], accounting for 52.47%, 51.32%, and 48.61% of the PM 2.5 mass concentration, respectively. In the Pingdingshan station, the proportion of water-soluble ions was the largest due to biomass combustion in the rural area. Additionally, SNA (SO 4 2- , NO 3 - , and NH 4 + ) were the main ionic components, accounting for 95.65%, 96.12%, and 97.33% of the total water-soluble ions, respectively. The mean values of SOR of the Wuhan (0.64) and Suizhou (0.63) stations were higher than that of the Pingdingshan station (0.50), whereas the NOR values of the Wuhan (0.18) and Pingdingshan (0.19) stations were higher than that of the Suizhou station (0.15). The difference in SOR and NOR among stations was affected by the secondary conversion mechanism, the ammonia-rich environment, and the surrounding traffic sources, respectively. The PM 2.5 at the Wuhan and Pingdingshan stations was in general alkaline, whereas at the Suizhou station it was neutral or weakly acidic, which was mainly caused by differences in NH 4 + . NH 4 + mainly existed in the form of (NH 4 ) 2 SO 4 and NH 4 NO 3 at the Wuhan and Pingdingshan stations, whereas at the Suizhou station it mainly existed in the form of (NH 4 ) 2 SO 4 or (NH 4 )HSO 4 . PCA-MLR analysis revealed that the Wuhan (89.27%) and Suizhou (67.38%) stations were the most affected by secondary conversion sources, whereas the Wuhan station was also affected by industrial sources (8.54%) and coal sources (2.27%). The pollution sources of the Suizhou station also included biomass combustion (24.42%) and dust sources (8.25%). The Pingdingshan station was most affected by biomass combustion (58.37%), followed by dust and combustion sources (38.05%) and traffic sources (3.58%). The analysis of potential sources of SNA (PSCF) showed that the main potential source areas of Wuhan were the boundary of Hubei, Henan, and Anhui and the southwest area of Anhui. Suizhou and Pingdingshan were affected by long-distance transport, and the main potential source regions were distributed in Shanghai, Jiangsu, and Anhui provinces from the east coast to the west.

China has always suffered from serious atmospheric fine particle (PM 2.5 ) pollution in winter, and PM 2.5 in Wuhan is particularly affected by regional transportation. Based on the hourly monitoring dataset of chemical components during the winter period, this study identified the real-time sources of PM 2.5 in Wuhan using a positive matrix factorization (PMF) model. A cluster analysis of backward trajectories and the concentration weighted trajectory were applied to obtain the potential source regions and transportation routes. During the observation period, ρ (PM 2.5 ) was (75.1±29.2) μg·m -3 , and there were two pollution episodes, one of which was mainly affected by the air masses coming from the northwest direction. In the first pollution episode, the increasing concentration of water-soluble ions was the main reason for the high PM 2.5 value, and the concentrations of NH 4 + , NO 3 - , and SO 4 2- were 1.6, 1.7, and 2.1 times those during the cleaning period, respectively. The other episode was affected by the air masses coming from the east direction, and the secondary organic components were clearly formed. Secondary inorganic aerosol contributed the most (34.1%) to PM 2.5 , followed by vehicular exhaust (23.7%), coal combustion (11.5%), road dust (10.9%), iron- and steel-producing processes (8.7%), and firework displays (5.7%). Biomass burning contributed the least (5.3%). Our examination of the diurnal variation revealed that the maximum contribution of iron- and steel-producing processes appeared at 08:00[(17.5±18.8) μg·m -3 ], and the lowest was at 01:00[(10.4±10.9) μg·m -3 ], which stayed high in the daytime and low at night. The contribution of vehicular exhaust showed a double peak at 09:00[(42.1±24.8) μg·m -3 ] and 20:00[(41.6±19.5) μg·m -3 ]. In the first pollution period, the contribution rate of secondary inorganic aerosol increased significantly, indicating that the long-distance transport under the northwest air mass promoted the generation of secondary components. In the second pollution period, the contribution rates of vehicular exhaust, coal combustion, iron- and steel-producing processes, and road dust increased, mainly located in the local area, the northwest of Jiangxi and the south of Anhui province. This reflected the influence of industrial processes, road transportation, and dust contribution along the Yangtze River on PM 2.5 . Biomass burning had a relatively high contribution for air masses from the northern regions, including Henan, Anhui, the south of Hebei, and the southwest of Shanxi provinces. The regional transport of pollutants from biomass combustion in the North China Plain during the winter would have an impact on Wuhan. This study can provide scientific and technological support for identifying the causes of atmospheric haze pollution in Wuhan during the winter and for the joint prevention and control of atmospheric particulate matter.

In recent years, frequent haze episodes have resulted in the deterioration of air quality of the Fenwei Plain during winter and holidays. Besides coal combustion and industrial emissions, the topography and climate of the Fenwei Plain were also the main causes of the haze. The samples were collected in Linfen of Fenwei Plain during the Spring Festival from February 2 to February 13, 2019. The 13 elements(Li, Be, Ti, Rb, Sc, Y, La, Ce, Zr, V, Tl, U, and Sn) in PM 2.5 were determined by inductively coupled plasma mass spectrometry(ICP-MS). Combined with the meteorological data, the spatial and temporal distribution of pollutants and potential source analysis were evaluated by cluster analysis and backward trajectory. The average concentration of SO 2 was 58.39 μg·m -3 during the sampling period, which exceeded the 24 h average mass concentration limit(50.00 μg·m -3 ) of national ambient air quality standard(GB 3095-2012). The average concentrations of O 3 , NO 2 , and CO was 52.15 μg·m -3 , 29.02 μg·m -3 , and 2.29 mg·m -3 , respectively. The results showed that SO 2 was the dominated pollutant. NO 2 and CO were mainly affected by diffusion from urban areas. The backward trajectory analysis indicated that the basin topography of the Fenwei Plain may be the main cause of the haze. The analysis of potential source contribution function(PSCF) of soil sources showed that the potential dominated areas included Northern Shaanxi, southern Gansu and Southern Ningxia., which were mainly affected by the monsoon climate.

This study provides data and theoretical support for the prevention and control of air pollution in central China. From January 13, 2018, to January 25, 2018, 48 PM 2.5 samples were collected in Huanggang by particulate matter samplers during a severe pollution episode. Twelve elements (Li, Be, V, Se, Sr, Mo, Ag, Ba, Tl, Th, Bi, and U) were analyzed by ICP-MS. A positive definite matrix factor (PMF), trajectory model of the cluster analysis, potential source analysis (PSCF), and the concentration weight analysis method (CWT) were applied to analyze the potential pollution sources and determine the transmission channel. The results showed that the internal cause of the pollution was the appearance of static, stable, and high humidity meteorological conditions, while the external cause was the input of pollution. Five types of pollution source were determined:fuel combustion (10.59%), crustal (24.22%), industry (3.16%), coal (47.57%), and traffic (14.45%). Two main types of air flow path were found; short distance transmission accounted for 62.50% whereas long distance transport accounted for 37.50%. The major contributors to the pollution included central and eastern Hubei, northeastern Hunan, southwestern Anhui, and southern Henan. North-south transmission channels were observed for central China. In addition to local pollution, the impact of regional transmission should not be ignored. In the emergency response period for heavy pollution during the autumn and winter, all regions need to control emission reduction measures. Joint prevention and control are the keys to air pollution control.

Eleven soil, three seawater and three passive air samples were collected from Qingbang Island in July, 2013, and 16 polycyclic aromatic hydrocarbons (PAHs) were analyzed. The distribution characteristics, possible sources and ecological risk assessment were investigated. The results showed that the concentrations of total 16 PAHs ranged between 60.30 and 123.34 ng x g(-1) with a mean value of 105.49 ng x g(-1) in soil, 45.96-101.08 ng x L(-1) with a mean value of 66.45 ng x L(-1) in seawater and 5.09-5.41 ng x d(-1) with a mean value of 5.35 ng x d(-1) in air samples, respectively. The PAHls concentrations of soil samples in tidal zone were higher than those in other areas. The highest PAHs concentrations in seawater were detected in complicated hydrological sea area. PAHs concentrations in air were equally distributed around the island. 2-4 rings PAHs were dominant species in soil, water and air samples. Ratio method and factor analysis were used to identify the possible sources of PAHs. The result suggested that PAHs in soil were mainly originated from combustion of coal, wood, diesel and petrol, while the possible sources of PAHls in water and air were mixed. The ecological risk assessment indicated that PAi s in different environment media posed little risk to people.

The typical karst Dashiwei Sinkholes located in Leye County, Guangxi were chosen as the study object. The air samples from the opening of Dashiwei Sinkholes to the underground river profiles were collected by polyurethane foam passive samplers (PUF-PAS), and the meteorological parameters were observed. The 16 PAHs were analyzed using GC-MS. The results showed that the total PAHs concentration in air in Dashiwei Sinkholes ranged from 33.76 ng x d(-1) to 150.86 ng x d(-1), with an average of 80.36 ng x d(-1). The mean concentrations in the cliff, the bottom and the underground river profiles were 67.17, 85.36 and 101.67 ng x d(-1), respectively. The 2-3 rings PAHs (including phenanthrene, anthracene, napnthalene and fluorene) accounted for 87.97% of the total of PAHs. The transport and accumulation processes of PAHs in air in Dashiwei Sinkholes were: the ground to the cliff section to the bottom section and then to the underground river, and the total PAHs concentrations showed an obvious increasing tendency with the decrease in altitude or increase in the length of the underground river. Low molecular weight PAHs compounds (including phenanthrene, anthracene, flourene and fluoranthene) in air went through differentiation at the bottom of the west peak, the bottom of the sinkhole and the underground river. The primary sources of PAHs were pyrogenic sources with atmosphere transport. Ambient temperature was the predominating factor influencing the transport and accumulation of gas phase PAHs in Dashiwei Sinkholes, following by wind speed, wind direction and relative humidity. Relative humidity and the temperature were the predominating factors influencing the differentiation, following by wind speed and wind direction. As a whole, a "cold trapping effect" of POPs was showed obviously in Dashiwei Sinkholes.

The investigation was performed on organochlorinated pesticides (OCPs) pollution in karst cavity atmosphere in Guilin City, South China. The total concentrations of OCPs outside the cave atmosphere ranged from 1.82 to 2.01 ng x m(-1), were far more than those of inside cave (range of 0.27-0.83 ng x m(-3)). OCPs concentrations fell gradually from cave gate to inside, especially to HCH, which reflected outside atmospheric transportation contributed most of pollutants inside cave. OCPs concentrations inside cave equaled to those in South and North poles therefore could be considered as background for OCPs research. The concentrations distribution sequence of HCH isomers corresponded to degradation rates themselves and that might provide critical information on the exhibiting their inherent character differences of HCH pesticides well under peculiarly original surrounding. In addition, a possibly fresh introduction of discofol-type and a historical usage potential for HCH pesticides in studied area were identified by isomer percentage combined isomer ratios.

Ship-board air samples were collected during the winter and spring cruise to the Pearl River Estuary (PRE) and adjacent South China Sea (SCS) in 2003 and were analyzed for organochlorine pesticides (OCPs). Meanwhile, air samples were collected at land-based sites in Guangzhou and Zhongshan for comparison. Results indicated that the detected OCPs were mainly of HCHs, DDTs and chlordane, its concentration ranged between 13-99, 73-390, 63-224 pg/m3 and 10-106, 429-1003, 1724-9638 pg/m3 during the winter and spring cruise, respectively. In general, the concentrations of OCPs were higher during spring cruise than in winter cruise. The measured OCPs concentration in the atmosphere over the PRE and adjacent SCS were found higher at sites close to continent and lower in outer sea, it is suggested that land-based source were to play a key role in the delivery of atmospheric OCPs. The alpha-HCH concentrations had significantly declined, higher gamma-HCH level may attribute to the present usage of lindane. Dicofol application and antifouling paints for fishing ships was suggested to be the important current "fresh" DDT source. The observed high level of chlordane during spring cruise could be related to the large amount usage of chlordane for termite control, as well as the long range transport from the west pacific region.

Weekly particulate and gas phase polycyclic aromatic hydrocarbons (PAHs) were sampled by a modified high-volume sampler in Guangzhou city from April 2001 to March 2002. The average total gas and particulate concentrations (sigma PAHs) were 312.9 ng/m3 and 23.7 ng/m3, respectively. The predominant PAHs in the air were 2 to approximately 4-ring compounds in vapor phase. Clear seasonal trends were observed, with higher concentration in summer and lower in winter for gas phase PAHs and adversely for particulate phase PAHs. Ambient temperature was predominating factor influencing the variation of gas phase PAHs concentrations and temperature together with wind speed and relative humidity were main meteorological parameters affecting the fluctuations of particle phase PAHs.