加油站场地油品渗漏探测及土壤污染评估

用洛阳铲采集某地区10座地下贮罐罐龄接近或超过10年的典型加油站场地不同深度土样,并分别用吹脱/捕集/热脱附/气相色谱法和快速溶剂萃取/硅酸镁净化/气相色谱法分析样品中的挥发性和萃取性石油烃,发现2座加油站疑似油品渗漏,其中1座为柴油渗漏,地下贮罐附近1.2 ～3.0 m深度土壤总石油烃含量16.1 ～24.6 g/kg,均超过荷兰土壤清除标准,另1座为汽油和柴油混合渗漏,其地下贮罐附近2.4m深度土壤总石油烃含量较高,但未超标.个别加油站场地较高的土壤天然有机物背景值可能计入EPH的分析结果,但其色谱指纹明显不同于石油烃.     

Effect of biochar on the fate of volatile petroleum hydrocarbons in an aerobic sandy soil

Biochar addition to soil is currently being investigated as a novel technology to remediate polluted sites. A critical consideration is the impact of biochar on the intrinsic microbial pollutant degradation, in particular at sites polluted with a mixture of readily biodegradable and more persistent organic pollutants. We therefore studied the impact of biochar (2% on dry weight basis) on the fate of volatile petroleum hydrocarbons in an aerobic sandy soil with batch and column studies. The soil-water partitioning coefficient, K(d), was enhanced in the biochar-amended soil up to a factor 36, and petroleum hydrocarbon vapor migration was retarded accordingly. Despite increased sorption, in particular of monoaromatic hydrocarbons, the overall microbial respiration was comparable in the biochar-amended and unamended soil. This was due to more rapid biodegradation of linear, cyclic and branched alkanes in the biochar amended soil. We concluded that the total petroleum hydrocarbon degradation rate was controlled by a factor other than substrate availability and the reduced availability of monoaromatic hydrocarbons in the biochar amended soil led to greater biodegradation of the other petroleum compounds.     

Careers in Air Pollution Control Plant Pathology

ABSTRACT

Profiles of the sources of nonmethane organic compounds (NMOCs) were developed for emissions from vehicles, petroleum fuels (gasoline, liquefied petroleum gas [LPG], and natural gas), a petroleum refinery, a smelter, and a cast iron factory in Cairo, Egypt. More than 100 hydrocarbons and oxygenated hydrocarbons were tentatively identified and quantified. Gasoline-vapor and whole-gasoline profiles could be distinguished from the other profiles by high concentrations of the C₅ and C₆ saturated hydrocarbons. The vehicle emission profile was similar to the whole-gasoline profile, with the exception of the unsaturated and aromatic hydrocarbons, which were present at higher concentrations in the vehicle emission profile. High levels of the C₂-C₄ saturated hydrocarbons, particularly n-butane, were characteristic features of the petroleum refinery emissions. The smelter and cast iron factory emissions were similar to the refinery emissions; however, the levels of benzene and toluene were greater in the former two sources. The LPG and natural gas emissions contained high concentrations of n-butane and ethane, respectively. The NMOC source profiles for Cairo were distinctly different from profiles for U.S. sources, indicating that NMOC source profiles are sensitive to the particular composition of petroleum fuels that are used in a location.     

Tank Atmosphere Perturbation: A Procedure for Assessing Flashing Losses from Oil Storage Tanks

Abstract

A new procedure to measure the total volume of emissions from heavy crude oil storage tanks is described. Tank flashing losses, which are difficult to measure, can be determined by correcting this value for working and breathing losses. The procedure uses a fan or blower to vent the headspace of the storage tank, with subsequent monitoring of the change in concentrations of oxygen or other gases. Combined with a separate determination of the reactive organic carbon (ROC) fraction in the gas, this method allows the evaluation of the total amount of ROC emitted. The operation of the system is described, and results from measurement of several storage tanks in California oil fields are presented. Our measurements are compared with those obtained using the California Air Resources Board (CARB) 150 method.     

Factors affecting the distribution of hydrocarbon contaminants and hydrogeochemical parameters in a shallow sand aquifer

The distributions of hydrocarbon contaminants and hydrogeochemical parameters were investigated in a shallow sand aquifer highly contaminated with petroleum hydrocarbons leaked from solvent storage tanks. For these purposes, a variety of field investigations and studies were performed, which included installation of over 100 groundwater monitoring wells and piezometers at various depths, soil logging and analyses during well and piezometer installation, chemical analysis of groundwater, pump tests, and slug tests. Continuous water level monitoring at three selected wells using automatic data-logger and manual measuring at other wells were also conducted. Based on analyses of the various investigations and tests, a number of factors were identified to explain the distribution of the hydrocarbon contaminants and hydrogeochemical parameters. These factors include indigenous biodegradation, hydrostratigraphy, preliminary pump-and-treat remedy, recharge by rainfall, and subsequent water level fluctuation. The permeable sandy layer, in which the mean water table elevation is maintained, provided a dominant pathway for contaminant transport. The preliminary pump-and-treat action accelerated the movement of the hydrocarbon contaminants and affected the redox evolution pattern. Seasonal recharge by rain, together with indigenous biodegradation, played an important role in the natural attenuation of the petroleum hydrocarbons via mixing/dilution and biodegradation. The water level fluctuations redistributed the hydrocarbon contaminants by partitioning them into the soil and groundwater. The identified factors are not independent but closely inter-correlated.     

Petroleum Pollutant Degradation by Surface Water Microorganisms (8 pp)

Background, Aims and Scope It is well known that the composition of petroleum or some of its processing products changes in the environment mostly under the influence of microorganisms. A series of experiments was conducted in order to define the optimum conditions for an efficient biodegradation of petroleum pollutant, or bioremediation of different segments of the environment. The aim of these investigations was to show to what extent the hydrocarbons of a petroleum pollutant are degraded by microbial cultures which were isolated as dominant microorganisms from a surface water of a wastewater canal of an oil refinery and a nitrogen plant. Biodegradation experiments were conducted on one paraffinic, and one naphthenic type of petroleum during a three month period under aerobic conditions, varying the following parameters: Inorganic (Kp) or an organic medium (Bh) with or without exposition to light. Methods Microorganisms were analyzed in a surface water sample from a canal (Pančevo, Serbia), into which wastewater from an oil refinery and a nitrogen plant is released. The consortia of microorganisms were isolated from the water sample (most abundant species: Phormidium foveolarum - filamentous Cyanobacteria, blue-green algae and Achanthes minutissima, diatoms, algae). The simulation experiments of biodegradation were conducted with the biomass suspension and crude oils Sirakovo (Sir, paraffinic type) and Velebit (Ve, naphthenic type). After a three month period, organic substance was extracted by means of chloroform. In the extracts, the content of saturated hydrocarbons, aromatic hydrocarbons, alcohols and fatty acids was determined (the group composition). n-Alkanes and isoprenoid aliphatic alkanes, pristane and phytane, in the aliphatic fractions, were analyzed using gas chromatography (GC). Total isoprenoid aliphatic alkanes and polycyclic alkanes of sterane and triterpane types were analyzed by GC-MS. Results and discussion. Paraffinic type petroleums have a significant loss of saturated hydrocarbons. For naphthenic type petroleum, such a trend has not been observed. The most intensive degradation of n-alkanes and isoprenoid aliphatic alkanes (in paraffinic oil) and isoprenoids (in naphthenic oil) was observed using the inorganic medium Kp in the light; the microbial conversion is somewhat lower with Kp in the dark; with organic medium Bh in the light the degradation is of low intensity; with the same medium in the dark the degradation is hardly to be seen. Steranes and triterpanes were not affected by microbial degradation under the conditions used in our experiments. Obviously, the petroleum biodegradation was restricted to the acyclic aliphatics (n-alkanes and isoprenoids). Conclusion Phormidium foveolarum (filamentous Cyanobacteria - blue-green algae) and Achanthes minutissima (diatoms, algae), microbial cultures isolated as dominant algae from a surface water in a wastewater canal of an oil refinery and a nitrogen plant, have degradable effects dominantly involving petroleum hydocarbons. Petroleum microbiological degradation is more intensive when inorganic medium (in the light) is applied. Having in mind that the inorganic pollutants have been released into the canal as well, this medium reflects more the natural environmental conditions. Polycyclic alkanes of sterane and triterpane type, in spite of the fact that these compounds could be degraded, have remained unchanged regarding abundance and distribution. Since this is the case even for naphthenic type petroleum (which is depleted in n-alkanes), it can be concluded that the biodegradation of petroleum type pollutants, under natural conditions, will be restrained to the n-alkane and isoprenoid degradation. Recommendation and Outlook Performed experiments and simulations of petroleum microbiological degradation may serve for the prediction of the fate of petroleum type pollutants, as well as for definition of conditions for bioremediation of some environmental segments.     

Organic Compounds in Cloud Water and their Deposition at a Remote Continental Site

Some organic compounds (alkylbenzene, chlorinated hydrocarbons and poiycyclic aromatic hydrocarbons) in clouds have been determined from samples collected above the canopy of a coniferous forest. The cloud samples were collected during 1987 and 1988 at Mt. Mitchell State Park, North Carolina, a remote high elevation (～2006 m MSL) continental site. Concentrations of the organic chemicals in clouds were in the range of 0.2 to ～200 ng mL^-1; and their estimated deposition rates via clouds were found to range from 1.58 * 10⁴ to 4.67 * 10⁶ ng m^-2 yr^-1. Great variations in concentrations were found which can best be explained, based on 72 hour back trajectory analysis, by different source locales and moving air masses. The concentration of these chemicals exceeded their water solubility as predicted by Henry's Law, suggesting that clouds are an excellent scavenger of organic chemicals in the ambient environment.     

Accuracy Assessment of EPA Protocol Gases Purchased In 1991

ABSTRACT

Fixed-roof tanks are used extensively at manufacturing, waste management, and other facilities to store or process liquids containing volatile organic compounds. Federal and state air standards require the control of organic air emissions from many of these tanks. A common practice used for some fixed-roof tanks that are required to use controls is to vent the tank through an activated carbon canister. When organic vapors are adsorbed on activated carbon, heat is released. Under certain conditions, the temperature of the carbon bed can increase to a level at which the carbon or organic vapors spontaneously ignite, starting a fire in the carbon bed. Bed fires in carbon canisters are not uncommon and can present a significant safety hazard at facilities if proper safety measures are not implemented. This article discusses how carbon adsorber bed fires occur and presents general guidance on safety measures for carbon canisters installed on fixed-roof tanks to reduce the likelihood of a carbon bed fire and to minimize the impact in the event of a fire.     

Performance of RBC coupled to a polyurethane foam to biodegrade petroleum refinery wastewater

Biological treatment of petroleum refinery wastewater was studied in a rotating biological contactor (RBC) coupled to a polyurethane foam (PUF) as a porous biomass support. The PUF was attached on both sides of biodisks. The biodegradation studies were carried out at varying hydraulic and organic loadings. COD removal efficiency of up to 87% was achieved. The results obtained in terms of biodegradation of COD, NH3-N, phenol, hydrocarbons and suspended solids in this study were compared with those in the literature. The RBC-PUF bioreactor was found to have a better performance than a conventional RBC for the biodegradation of the above mentioned parameters. A higher concentration of active biomass (77 g TVS/m2) was observed in the RBC-PUF as compared to other treatment systems. A linear relationship between COD applied and COD removed was observed for the combined four stage system as well as for the individual stages.     

The Effectiveness of Aeration Recirculation in Controlling VOC Emissions from Publicly Owned Treatment Works

Abstract

The effects of aeration recirculation on oxygen transfer and the fate of five volatile organic compounds (VOCs) commonly found in publicly owned treatment works (POTWs) influent are studied using various modeling approaches. The five compounds are benzene, chloroform, methylene chloride, toluene, and trichloroethylene. The models predict that the overall oxygen transfer efficiency can be increased by 96.7% at 50% aeration recirculation with only a 9.6% drop in oxygen transfer rate. The emission reductions and biodegradation improvements are compound specific; for the compounds investigated here, about 40% emission reductions and 16% biodegradation increases can be achieved at 50% aeration recirculation. The temperature effect on the VOC fate mechanisms is also investigated. Overall, the model predictions reveal that up to 50% aeration recirculation is effective in controlling VOC emissions.     

Direct Measurement of Fugitive Emissions of Hydrocarbons from a Refinery

Abstract

Refineries are a source of emissions of volatile hydrocarbons that contribute to the formation of smog and ozone. Fugitive emissions of hydrocarbons are difficult to measure and quantify. Currently these emissions are estimated based on standard emission factors for the type and use of equipment installed. Differential absorption light detection and ranging (DIAL) can remotely measure concentration profiles of hydrocarbons in the atmosphere up to several hundred meters from the instrument. When combined with wind speed and direction, downwind vertical DIAL scans can be used to calculate mass fluxes of the measured gas leaving the site. Using a mobile DIAL unit, a survey was completed at a Canadian refinery to quantify fugitive emissions of methane, C₂₊ hydrocarbons, and benzene and to apportion the hydrocarbon emissions to the various areas of the refinery. Refinery fugitive emissions as measured with DIAL during this demonstration study were 1240 kg/hr of C₂₊ hydrocarbons, 300 kg/hr of methane, and 5 kg/hr of benzene. Storage tanks accounted for over 50% of the total emissions of C₂₊ hydrocarbons and benzene. The coker area and cooling towers were also significant sources. The C₂₊ hydrocarbons emissions measured during the demonstration amounted to 0.17% of the mass of the refinery hydrocarbon throughput for that period. If the same loss were repeated throughout the year, the lost product would represent a value of US$3.1 million/yr (assuming US$40/bbl). The DIAL-measured hourly emissions of C₂₊ hydrocarbons were 15 times higher than the emission factor estimates and gave a different perspective on which areas of the refinery were the main source of emissions. Methods, such as DIAL, that can directly measure fugitive emissions would improve the effectiveness of efforts to reduce emissions, quantify the reduction in emissions, and improve the accuracy of emissions data that are reported to regulators and the public.     

Biodegradation of hydrocarbons vapors: Comparison of laboratory studies and field investigations in the vadose zone at the emplaced fuel source experiment, Airbase Vaerløse, Denmark

The natural attenuation of volatile organic compounds (VOCs) in the unsaturated zone can only be predicted when information about microbial biodegradation rates and kinetics are known. This study aimed at determining first-order rate coefficients for the aerobic biodegradation of 13 volatile petroleum hydrocarbons which were artificially emplaced as a liquid mixture during a field experiment in an unsaturated sandy soil. Apparent first-order biodegradation rate coefficients were estimated by comparing the spatial evolution of the resulting vapor plumes to an analytical reactive transport model. Two independent reactive numerical model approaches have been used to simulate the diffusive migration of VOC vapors and to estimate degradation rate coefficients. Supplementary laboratory column and microcosm experiments were performed with the sandy soil at room temperature under aerobic conditions. First-order kinetics adequately matched the lab column profiles for most of the compounds. Consistent compound-specific apparent first-order rate coefficients were obtained by the three models and the lab column experiment, except for benzene. Laboratory microcosm experiments lacked of sensitivity for slowly degrading compounds and underestimated degradation rates by up to a factor of 5. Addition of NH3 vapor was shown to increase the degradation rates for some VOCs in the laboratory microcosms. All field models suggested a significantly higher degradation rate for benzene than the rates measured in the lab, suggesting that the field microbial community was superior in developing benzene degrading activity.     

Careers in Air Pollution Control Monitoring-Surveillance

ABSTRACT

The temporal and longitudinal characteristics of volatile organic compound (VOC) emissions from the aeration units of a publicly owned treatment works (POTWs) have been investigated by systematic monitoring and mathematical modeling. Field tests have been conducted at a 120-mgd wastewater treatment plant to investigate the hourly, weekly, and seasonal changes of VOC emissions. Variations of VOC emissions along the length of the aeration units have been tested and modeled. Most VOCs have decreasing concentration profiles. Henry's law coefficients and biodegradation constants for the detected compounds have been validated with the improved models and the field test data. More than one-half of the emissions were found to have been generated from the first one-third of the aeration unit length.     

Trends in the management of waste tyres and recent experimental approaches in the analysis of polycyclic aromatic hydrocarbons (PAHs) from rubber crumbs

The health and environmental consciousness of waste tires has increased tremendously over the years. This has motivated efforts to develop secondary applications that will utilize tire when they reach the end of their life cycle and limit their disposal in landfills. Among the applications of waste tires which are discussed in this review, the use of rubber crumbs in artificial turf fields has gained worldwide attention and is increasing annually. However, there are serious concerns regarding chemicals that are used in the manufacturing process of tires, which ultimately end up in rubber crumbs. Chemicals such as polycyclic aromatic hydrocarbons (PAH) and heavy metals which are found in rubber crumbs have been identified as harmful to human health and the environment. This review paper is intended to highlight some of the methods which have been used to manage waste tire; it also looks at chemicals/materials used in tire compounding which are identified as possible carcinogenic.

     

Analytical approaches for determining human exposure to pesticides

Abstract

The presence of pesticides, both persistent and biodegradable, in the environment is a problem which is both significant and potentially dangerous to humans. An index of biodegradability is presented which is based on the correlation between environmental stability and fat solubility. Halogenated pesticides are, therefore, both more fat soluable and more resistant to biodegradation, while methylated pesticides are more water soluable and, therefore, more biodegradable. Three methods for detecting low‐levels of halogenated pesticides are presented: the Macro, the Micro “Florisil,”; and the Micro “Silica.”; A method is also presented to detect these chemicals in blood. Two methods for the detection of nonpersistent, organophosphorus and carbamate insecticides, Cholinesterase inhibition and urinary metabolites, are described. Finally, methods of monitoring human exposure through the detection of phenols, phenoxy acids, alkyl phophates, and anilines are presented.     

Sorption and Biodegradation of Vapor-Phase Organic Compounds with Wastewater Sludge and Food Waste Compost

ABSTRACT

To test the possible use of composted food waste and wastewater sludge as biofilters to treat gas-phase volatile organic compounds (VOCs), batch experiments were conducted with an isolated strain that could degrade aromatic compounds under aerobic conditions. A benzene and trichloroethylene (TCE) mixture was used as the gas-phase pollutant in experiments with composted food waste, sludge, and soil. Under aerobic conditions, benzene was degraded as a primary substrate and TCE was degraded cometabolically, with water contents varying from 6 to 60% (volume of water added/volume of solid). Optimal water content for VOC removal was 12% for the soil, 36% for the composted food waste, and 48% for the sludge.

The extent of VOC sorption and biodegradation at the optimal water content was different for each material. With the same initial VOC concentration, more VOCs were removed by sorption onto the composted food waste and the sludge, while less VOCs were biodegraded in comparison with the results using soil. The reason the biodegradation in the soil was greater may be partly attributed to the fact that, due to less sorption, the aqueous-phase concentration of VOCs, which microorganisms could utilize as a carbon source or cometabolize, was higher. We also speculate that the distribution of microorganisms in each medium affects the rate of biodegradation. A large number of microorganisms were attached to the composted food waste and sludge. Mass transfer of VOCs and oxygen to these microorganisms, which appear to have been heterogeneously distributed in clusters, may have been limited, resulting in hindered biodegradation.     

Biofiltration of a Mixture of Volatile Organic Emissions

ABSTRACT

Air biofiltration is now under active consideration for the removal of the volatile organic compounds (VOCs) from polluted airstreams. To optimize this emerging environmental technology and to understand compound removal mechanisms, a biofilter packed with peat was developed to treat a complex mixture of VOCs: oxygenated, aromatic, and chlorinated compounds. The removal efficiency of this process was high. The maximum elimination capacity (ECmax) obtained was ~120 g VOCs/m³ peat/hr. Referring to each of the mixture's components, the ECmax showed the limits in terms of biodegradability of VOCs, especially for the halogenated compounds and xylene.

A stratification of biodegradation was observed in the reactor. The oxygenated compounds were metabolized before the aromatic and halogenated ones. Two assumptions are suggested. There was a competition between bacterial communities. Different communities colonized the peat-based biofilter, one specialized for the elimination of oxygenated compounds, the others more specialized for elimination of aromatic and halogenated compounds. There was also substrate competition. Bacterial communities were the same over the height of the column, but the more easily biodegradable compounds were used first for the microorganism metabolism when they were present in the gaseous effluent.     

Bioremediation of a weathered and a recently oil-contaminated soils from Brazil: a comparison study

The facility with which hydrocarbons can be removed from soils varies inversely with aging of soil samples as a result of weathering. Weathering refers to the result of biological, chemical and physical processes that can affect the type of hydrocarbons that remain in a soil. These processes enhance the sorption of hydrophobic organic contaminants (HOCs) to the soil matrix, decreasing the rate and extent of biodegradation. Additionally, pollutant compounds in high concentrations can more easily affect the microbial population of a recently contaminated soil than in a weathered one, leading to inhibition of the biodegradation process. The present work aimed at comparing the biodegradation efficiencies obtained in a recently oil-contaminated soil (spiked one) from Brazil and an weathered one, contaminated for four years, after the application of bioaugmentation and biostimulation techniques. Both soils were contaminated with 5.4% of total petroleum hydrocarbons (TPHs) and the highest biodegradation efficiency (7.4%) was reached for the weathered contaminated soil. It could be concluded that the low biodegradation efficiencies reached for all conditions tested reflect the treatment difficulty of a weathered soil contaminated with a high crude oil concentration. Moreover, both soils (weathered and recently contaminated) submitted to bioaugmentation and biostimulation techniques presented biodegradation efficiencies approximately twice as higher as the ones without the aforementioned treatment (natural attenuation).     

Comprehensive Environmental Investigation at Former Industrial/Petroleum Underground Storage Tank Sites in Long Beach,CA: A Forensic Perspective

Two industrial sites were investigated based on years of available hydrogeologic information and monitoring data for soil and groundwater. Collected data were forensically evaluated using age-dating and fingerprinting methods. The previous business uses of the project sites were as a gas station, laundry/dry-cleaning service, and car wash with petroleum underground storage tanks (USTs). As a result, these sites were exposed to a number of toxic contaminants at relatively high concentrations. Source control was necessary for successful remediation and the ultimate removal of the remaining compounds from these industrial sites. Although contaminated soil around the source was excavated during the remedial action and the high concentrations of contaminants were reduced, typical groundwater contaminants such as petroleum hydrocarbons as gasoline (TPH-G), benzene, toluene, ethylbenzene, xylenes (BTEX), and oxygenates including methyl tert-butyl ether (MTBE), diisopropyl ether (DIPE), ethyl tert-butyl ether (ETBE), tert-amyl methyl ether (TAME), and tert-butyl alcohol (TBA) were persistently found at the studied sites around the source points. The plume and concentration of contaminants had changed their shapes and strength for all monitoring periods. Thus, additional source control seems to be a requirement for the complete removal of source contamination, which must be ascertained with groundwater and soil monitoring on a regular time base. For the study sites, monitored natural attenuation was relatively feasible for the long-term plan; however, it did not offer a perfect remediation solution for an ultimate goal because of residual toxic compounds that might have affected the surrounding residential areas at higher concentrations than their health limits. Therefore, as a remediation strategy, the combination of clean-up technology and natural attenuation with monitoring activities are more highly recommended than either clean-up or natural attenuation used separately.     

Recalcitrance of polycyclic aromatic hydrocarbons in soil contributes to background pollution

The microbial accessibility of native phenanthrene and pyrene was determined in soils representing background scenarios for pollution by polycyclic aromatic hydrocarbons (PAHs). The soils were selected to cover a wide range of concentrations of organic matter (1.7-10.0%) and total PAHs (85-952 μg/kg). The experiments included radiorespirometry determinations of biodegradation with ¹⁴C-labeled phenanthrene and pyrene and chemical analyses to determine the residual concentrations of the native compounds. Part of the tests relied on the spontaneous biodegradation of the chemicals by native microorganisms; another part also involved inoculation with PAH-degrading bacteria. The results showed the recalcitrance of PAHs already present in the soils. Even after extensive mineralization of the added ¹⁴C-PAHs, the concentrations of native phenanthrene and pyrene did not significantly decrease. We suggest that aging processes operating at background concentrations may contribute to recalcitrance and, therefore, to ubiquitous pollution by PAHs in soils.