Measured and estimated benzene and volatile organic carbon (VOC) emissions at a major U.S. refinery/chemical plant: Comparison and prioritization

Factors affecting prevalence of neurological symptoms among workers at gasoline stations in Rayong Province, Thailand

This cross-sectional study was aimed at assessing the exposure to organic solvents and the factors affecting prevalence of neurological symptoms among workers at gas stations in Rayong Province. The sample included 200 workers at gas stations, including refueling staff, cashiers, food shop, coffee shop, and convenience store employees. Interview questionnaire included general information, work history, and neurological symptoms. Urine collection devices were used to detect organic solvents metabolized in urine, including t,t-muconic acid (t,t-MA), hippulic acid (HA), mandelic acid (MA), and methylhppuric acid (MHA).The results showed that the workers’ medians (interquartile range: IQR) of the metabolized organic solvents were as follows: t,t-MA was 393.62 (244.59) µg/g Cr, HA was 0.32 (0.14) g/g Cr, MA was 0.06 (0.02) g/g Cr, and MHA was 0.40 (0.13) g/g Cr. For prevalence of neurological symptoms, top three symptoms were headache (49.0%), dizziness (42.5%), and stress/irritability (38.5%). Working at a gas station present was neurological symptoms more than in the past was 32.5%. According to the assessment of exposure to metabolized organic solvents and factors affecting the prevalence of neurological symptoms, overtime work ≥ 6 hours and HA content greater than quartiles Q3 had an effect on neurologic symptoms (OR=2.17; 95%CI=1.23-5.10 and OR=2.15; 95%CI=1.18- 4.76, respectively). In summary, time spent working in gas stations and exposure to toluene organic solvents can cause neurological symptoms. It is recommended to reduce overtime or add breaks during work shifts or shift changes. In addition, workers should be away from the solvent.

Mass Concentration, Source and Health Risk Assessment of Volatile Organic Compounds in Nine Cities of Northeast China

From April 2008 to July 2009, ambient measurements of 58 volatile organic compounds (VOCs), including alkanes, alkenes, and aromatics, were conducted in nine industrial cities (Shenyang, Fushun, Changchun, Jilin, Harbin, Daqing, Huludao, Anshan and Tianjin) of the Northeast Region, China (NRC). Daqing had the highest concentration of VOCs (519.68 ± 309.88 μg/m3), followed by Changchun (345.01 ± 170.52 μg/m3), Harbin (231.14 ± 46.69 μg/m3), Jilin (221.63 ± 34.32 μg/m3), Huludao (195.92 ± 103.26 μg/m3), Fushun (135.43 ± 46.01 μg/m3), Anshan (109.68 ± 23.27 μg/m3), Tianjin (104.31 ± 46.04 μg/m3), Shenyang (75.2 ± 40.09 μg/m3). Alkanes constituted the largest percentage (>40%) in concentrations of the quantified VOCs in NRC, and the exception was Tianjin dominated by aromatics (about 52.34%). Although alkanes were the most abundant VOCs at the cities, the most important VOCs contributing to ozone formation potential (OFP) were alkenes and aromatics. Changchun had the highest OFP (537.3 μg/m3), Tianjin had the lowest OFP (111.7 μg/m3). The main active species contributing to OFP in the nine cities were C2~C6 alkanes, C7~C8 aromatic hydrocarbons, individual cities (Daqing) contained n-hexane, propane and other alkane species. Correlation between individual hydrocarbons, B/T ratio and principal component analysis model (PCA) were deployed to explore the source contributions. The results showed that the source of vehicle exhausts was one of the primary sources of VOCs in all nine cities. Additionally, individual cities, such as Daqing, petrochemical industry was founded to be an important source of VOCs. The results gained from this study provided a large of useful information for better understanding the characteristics and sources of ambient VOCs incities of NRC. The non-carcinogenic risk values of the nine cities were within the safe range recognized by the U.S. Environmental Protection Agency (HQ < 1), and the lifetime carcinogenic risk values of benzene were 3.82 × 10−5~1.28 × 10−4, which were higher than the safety range specified by the US Environmental Protection Agency (R < 1.00 × 10−6). The results of risk values indicated that there was a risk of cancer in these cities.

Comprehensive chemical characterization of dissolved organic matter in typical point-source refinery wastewaters

In petroleum refineries, the electric desalting, distillation, and stripping processes could generate large amounts of wastewaters that contain toxic substances. In this study, eight wastewater samples were collected from the three typical refining processes for comprehensive chemical characterization of the dissolved organic matter (DOM) using excitation emission matrix fluorescence spectroscopy, gas chromatography-mass spectrometry, and Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). Results showed that protein-like components and benzene were ubiquitous in all these wastewaters. Oxygen-containing volatile organic compounds had higher contents in crude distillation and stripping wastewater than those in electric desalting wastewater. Among the three refinery processes, molecular composition of DOM in the stripping wastewater had the highest complexity. The O_x and O_xS_y class species assigned from the negative-ion electrospray ionization FT-ICR MS were dominant in all wastewaters. The O_xS₂ class species which were effectively removed during stripping treatment had highest relative abundance in stripping influent. These results are instructive to guide the development of "divide and conquer" and would improve the treatment and management of refinery wastewater streams.

Definition of an Emission Factor for VOC Emitted from Italian and European Refineries

Refineries are a major source of atmospheric emissions, which typically include CO, SO2, NOX, particulates, and volatile organic compounds (VOCs). There has been an increasing level of attention toward the emissions of VOCs related to their environmental impact as well as their potential to cause adverse effects on human health and the discomfort associated with their unpleasant odor. In general, an emission factor (EF) represents a model for a first order estimate of emissions, which correlates the quantity of pollutant released into the atmosphere with a so-called “activity index” related to the release of that pollutant. Based on the study of the scientific and technical literature regarding the Italian and European refining scenarios, an attempt was made to verify the existence of a correlation between the size of a refinery and the related total VOC emissions. Once this correlation was evaluated, it was possible to develop an emission factor for VOC emissions considering the plant capacity as the related activity index. After collecting and analyzing data concerning operative capacity and total VOCs emitted from 15 refineries in 2018, the resulting emission factor turned out to be equal to 188 ± 166 g per ton of crude oil processed. This value is in agreement with the range of 50–1000 g/ton reported in the European Best Available Techniques Reference Document for the Refining of Mineral Oil and Gas.

Detection of multiple chemicals based on external cavity quantum cascade laser spectroscopy

A laser spectroscopy system based on a broadband tunable external cavity quantum cascade laser (ECQCL) and a mini quartz crystal tuning fork (QCTF) detector was developed for standoff detection of volatile organic compounds (VOCs). The self-established spectral analysis model based on multiple algorithms for quantitative and qualitative analysis of VOC components (i.e. ethanol and acetone) was detailedly investigated in both closed cell and open path configurations. A good agreement was obtained between the experimentally observed spectra and the standard reference spectra. For open path detection of VOCs, the sensor system was demonstrated at a distance of 30m. The preliminary laboratory results show that standoff detection of VOCs at a distance of over 100m is very promising.

Emission characteristics of volatile organic compounds and their secondary organic aerosol formation potentials from a petroleum refinery in Pearl River Delta, China

A campaign was carried out to measure the emission characteristics of volatile organic compounds (VOCs) in different areas of a petroleum refinery in the Pearl River Delta (PRD) region in China. In the refining area, 2-methylpentane, 2,3-dimethylbutane, methylcyclopentane, 3-methylhexane, and butane accounted for >50% of the total VOCs; in the chemical industry area, 2-methylpentane, p-diethylbenzene, 2,3-dimethylbutane, m-diethylbenzene and 1,2,4-trimethylbenzene were the top five VOCs detected; and in the wastewater treatment area, the five most abundant species were 2-methylpentane, 2,3-dimethylbutane, methylcyclopentane, 3-methylpentane and p-diethylbenzene. The secondary organic aerosol (SOA) formation potential was estimated using the fractional aerosol coefficients (FAC), secondary organic aerosol potential (SOAP), and SOA yield methods. The FAC method suggests that toluene, p-diethylbenzene, and p-diethylbenzene are the largest contributors to the SOA formation in the refining, chemical industry, and wastewater treatment areas, respectively. With the SOAP method, it is estimated that toluene is the largest contributor to the SOA formation in the refining area, but o-ethyltoluene contributes the most both in the chemical industry and wastewater treatment areas. For the SOA yield method, aromatics dominate the yields and account for nearly 100% of the total in the three areas. The SOA concentrations estimated of the refining, chemical industry and wastewater treatment areas are 30, 3835 and 137μgm^-3, respectively. Despite the uncertainties and limitations associated with the three methods, the SOA yield method is suggested to be used for the estimation of SOA formation from the petroleum refinery. The results of this study have demonstrated that the control of VOCs, especially aromatics such as toluene, ethyltoluene, benzene and diethylbenzene, should be a focus of future regulatory measures in order to reduce PM pollution in the PRD region.

Estimating Emissions of Toxic Hydrocarbons from Natural Gas Production Sites in the Barnett Shale Region of Northern Texas

Oil and natural gas operations have continued to expand and move closer to densely populated areas, contributing to growing public concerns regarding exposure to hazardous air pollutants. During the Barnett Shale Coordinated Campaign in October, 2013, ground-based whole air samples collected downwind of oil and gas sites revealed enhancements in several potentially toxic volatile organic compounds (VOCs) when compared to background values. Molar emissions ratios relative to methane were determined for hexane, benzene, toluene, ethylbenzene, and xylene (BTEX compounds). Using methane leak rates measured from the Picarro mobile flux plane (MFP) system and a Barnett Shale regional methane emissions inventory, the rates of emission of these toxic gases were calculated. Benzene emissions ranged between 51 ± 4 and 60 ± 4 kg h^-1. Hexane, the most abundantly emitted pollutant, ranged from 642 ± 45 to 1070 ± 340 kg h^-1. While observed hydrocarbon enhancements fall below federal workplace standards, results may indicate a link between emissions from oil and natural gas operations and concerns about exposure to hazardous air pollutants. The larger public health risks associated with the production and distribution of natural gas are of particular importance and warrant further investigation, particularly as the use of natural gas increases in the United States and internationally.

Source attribution and quantification of benzene event emissions in a Houston ship channel community based on real-time mobile monitoring of ambient air

A mobile laboratory equipped with a proton transfer reaction mass spectrometer (PTR-MS) operated in Galena Park, Texas, near the Houston Ship Channel during the Benzene and other Toxics Exposure Study (BEE-TEX). The mobile laboratory measured transient peaks of benzene of up to 37 ppbv in the afternoon and evening of February 19, 2015. Plume reconstruction and source attribution were performed using the four-dimensional (4D) variational data assimilation technique and a three-dimensional (3D) micro-scale forward and adjoint air quality model based on mobile PTR-MS data and nearby stationary wind measurements at the Galena Park Continuous Air Monitoring Station (CAMS). The results of inverse modeling indicate that significant pipeline emissions of benzene may at least partly explain the ambient concentration peaks observed in Galena Park during BEE-TEX. Total pipeline emissions of benzene inferred within the 16-km(2) model domain exceeded point source emissions by roughly a factor of 2 during the observational episode. Besides pipeline leaks, the model also inferred significant benzene emissions from marine, railcar, and tank truck loading/unloading facilities, consistent with the presence of a tanker and barges in the Kinder Morgan port terminal during the afternoon and evening of February 19. Total domain emissions of benzene exceeded corresponding 2011 National Emissions Inventory (NEI) estimates by a factor of 2-6.

IMPLICATIONS

Port operations involving petrochemicals may significantly increase emissions of air toxics from the transfer and storage of materials. Pipeline leaks, in particular, can lead to sporadic emissions greater than in emission inventories, resulting in higher ambient concentrations than are sampled by the existing monitoring network. The use of updated methods for ambient monitoring and source attribution in real time should be encouraged as an alternative to expanding the conventional monitoring network.