Potential Sources Of Volatile Organic Compounds Research Articles

Greenland Ice Sheet Surfaces Colonized by Microbial Communities Emit Volatile Organic Compounds.

Volatile organic compounds (VOCs) are emitted by organisms for a range of physiological and ecological reasons. They play an important role in biosphere–atmosphere interactions and contribute to the formation of atmospheric secondary aerosols. The Greenland ice sheet is home to a variety of microbial communities, including highly abundant glacier ice algae, yet nothing is known about the VOCs emitted by glacial communities. For the first time, we present VOC emissions from supraglacial habitats colonized by active microbial communities on the southern Greenland ice sheet during July 2020. Emissions of C5–C30 compounds from bare ice, cryoconite holes, and red snow were collected using a push–pull chamber active sampling system. A total of 92 compounds were detected, yielding mean total VOC emission rates of 3.97 ± 0.70 μg m–2 h–1 from bare ice surfaces (n = 31), 1.63 ± 0.13 μg m–2 h–1 from cryoconite holes (n = 4), and 0.92 ± 0.08 μg m–2 h–1 from red snow (n = 2). No correlations were found between VOC emissions and ice surface algal counts, but a weak positive correlation (r = 0.43, p = 0.015, n = 31) between VOC emission rates from bare ice surfaces and incoming shortwave radiation was found. We propose that this may be due to the stress that high solar irradiance causes in bare ice microbial communities. Acetophenone, benzaldehyde, and phenylmaleic anhydride, all of which have reported antifungal activity, accounted for 51.1 ± 11.7% of emissions from bare ice surfaces, indicating a potential defense strategy against fungal infections. Greenland ice sheet microbial habitats are, hence, potential sources of VOCs that may play a role in supraglacial microbial interactions, as well as local atmospheric chemistry, and merit future research efforts.

Characteristics and Source Apportionment of VOCs and O3 in Shijiazhuang

To study the composition characteristics and sources of volatile organic compounds (VOCs) in Shijiazhuang City, three national control points were selected to conduct VOCs sampling and analysis from March 2017 to January 2018. The correlation of VOCs through combination with meteorological and ground-level O3 data, and the sources of VOCs were analyzed by positive matrix factorization (PMF). To quantify the pollution period of O3 in summer, its temporal sequence characteristics were studied by wavelet analysis. During the sampling period, the average concentration of ambient total VOCs (TVOCs) was (137.23±64.62) μg·m-3. Haloalkanes were the most dominant VOC compounds, accounting for 31.77% of total VOCs mass, followed by aromatic (30.97%) and oxygenated VOCs (OVOCs, 23.76%). The seasonal variation in VOC concentration followed the trend in winter (187.7 μg·m-3) > autumn (146.8 μg·m-3) > spring (133.24 μg·m-3) > summer (107.1 μg·m-3); the concentration of VOCs shows a trend of increasing gradient from west to east. The O3 concentration correlated negatively with VOCs and NO2, and positively with temperature, sunshine duration, wind speed, and visibility. Changes in meteorological elements were concerned before the occurrence of ozone pollution in summer, especially in 4-5 days in June and 7-8 days during July to August after the occurrence of increasing temperature. Finally six potential sources of VOCs were quantified by the PMF model, including from gasoline emissions (24.78%), diesel vehicle emissions (24.69%), solvent usage (18.64%), the chemical industry (11.87%), regional background (10.84%), and the pharmaceutical industry (9.17%). Ozone formation potential (OFP) contribution of emission sources of gasoline and diesel vehicles (54.98%) was over half of the total contribution. Meanwhile, these findings illustrated that control of vehicle emissions and industrial sources would be an important way to reduce VOCs concentrations and improve air quality in Shijiazhuang.

Characteristics and Source Apportionment of Atmospheric VOCs in the Nanjing Industrial Area in Autumn

Atmospheric volatile organic compounds (VOCs) were continuously monitored via an online GC-FID/MS system in Nanjing during the autumn of 2018 to analyze the chemical characteristics, ozone formation potential (OFP), and potential sources of VOCs in this industrial region. During the sampling period, the average concentration of atmospheric total VOCs (TVOCs) was (64.3±45.6)×10-9. Alkanes were the most predominant VOC compound, accounting for 33.1% of the TVOC mass, followed by oxygenated volatile organic compounds (OVOCs, 22.3%) and halogenated hydrocarbons (21.8%). The diurnal cycles of VOCs revealed "bimodal" distributions. The higher concentrations of VOCs observed at 06:00-07:00 and 18:00-20:00 were attributed to the intense traffic emissions and meteorological conditions. Furthermore, maximum incremental reaction (MIR) analysis was used to estimate OFP of VOCs. The results showed that the calculated OFP in Nanjing was 267.1 μg·m-3. Aromatic hydrocarbons and alkenes were the dominant contributors to OFPs, which accounted for 55.2% and 20.8% to the total OFPs, respectively. Finally, five potential sources of VOCs were quantified by the positive matrix factorization model, including traffic emissions (34%), industrial emissions (19%), liquefied petroleum gas (LPG) emissions (17%), usage of paints and solvents (16%), coal combustion, and biomass burning (14%). These findings suggested that control of vehicle emissions and industrial sources would be an important way to reduce VOC concentrations and improve air quality in Nanjing.

Screening of Emerging Volatile Organic Contaminants in Shallow Groundwater in East China

In order to collect baseline information on the environmental occurrence of volatile organic compounds (VOCs) in groundwater in East China, shallow groundwater samples were collected from five alluvial plains in East China in 2008 to 2009. All samples were analyzed for 54 VOCs representing a wide variety of uses and origins. Sampling sites were mainly selected in the areas to be susceptible to contamination from human activities in terms of previous hydrogeological survey. The data of all samples showed a variety of different hydrogeological systems with potential sources of VOCs, with 36 of the 54 VOCs being found. The most frequently detected compounds include naphthalene (56.9%), chloroform (16.9%), 1,2‐dichloroethane (16.2%), 1,2‐dichloropropane (13.1%), and 1,2,3‐trichlorobenzene (12.3%). The concentrations of methylene chloride, 1,2‐dichloroethane, carbon tetrachloride, trichloroethene, 1,2‐dichloropropane, and tetrachloroethene exceeded the relating drinking water standards. Future work will be needed to identify those factors that are most important in determining the occurrence and concentrations of VOCs in groundwater in China.

Assessment of Air Quality in Ninety-Nine Residences of Kuwait

In the present study, we investigate volatile organic compounds (VOCs) in residences of Kuwait. The objectives were to characterize indoor air exposures to VOCs and to identify potential sources of VOCs, wherever possible. A random sample of 99 residences was selected from all the five governorates of Kuwait during the period from December 1994 to June 1996 and concentrations of the compounds from indoors and outdoors were sampled. Using the statistical techniques of factor analysis on indoor and outdoor samples, we reduced the number of pollutants to four new variables (or factors) separately for the indoor data and for the outdoor data. These factors were related to certain source characteristics in an attempt to identify the potential sources of the pollutants.