Gasoline In Soil Research Articles

Gasoline degradation and nitrogen fixation in soil by pulsed corona discharge plasma

Gasoline contaminated soil poses an environmental and human health problem, which may be partially solved by the emerging non-thermal plasma technology. In this study a pulse corona discharge (PCD) reactor was employed to degrade gasoline in soil and simultaneously to fix nitrogen in soil. The gasoline removal rates were influenced by input power, electrode gap, gas flow rate, initial gasoline concentration, soil pH, and soil moisture. This technology produced no secondary pollution. Ozone, NOx, and hydroxyl radicals, generated directly on the soil surface, were identified as the primary agents responsible for gasoline degradation. The role of the major active agents was determined by ventilating different gases during the corona discharges. In addition, the concentration of nitrate and wettability of soil was increased after the treatment. Safety and fertility of treated soil were investigated by planting lettuce. Thus, soil pollution was remediated using this non-thermal plasma treatment, while simultaneously improving soil nitrogen content and physical characteristics. This process potentially enhances soil fertility and revegetation, since this environmentally-friendly method does not involve other chemicals injections.

Evaluation of the Potential of Burningbush (Kochia scoparia (L.) Schard) and Maize (Zea mays L.) and the Role of Soil Organic Amendment in Phytoremediation of Gasoline-Contaminated Soils

A greenhouse study was conducted to investigate the performance of burningbush (Kochia scoparia (L.) Schard) and maize (Zea mays L.) in removal of hydrocarbons from soils contaminated with different levels of gasoline. Plants’ capability to grow in gasoline-spiked soils was also evaluated. Additionally, peat fertilizer applied to selected treatments to identify the role of organic amendment of soil on plant growth and remediation potential in contaminated soil. Both studied plant species were found to tolerate gasoline contamination up to the highest applied concentration, i.e., 10,000 mg/kg; however, seedling emergence and subsequent growth were affected in the presence of various levels gasoline in soil. Germination, biomass and root length of burningbush and maize significantly decreased in the presence of higher levels of gasoline (P < 0.05). Positive influence of soil amendment with peat on plant growth and phytoremediation performance was achieved. Remediation ability of both plant species was altered by variation in gasoline content of soil. For instance, increase in gasoline content of unamended soils from 1000 to 10,000 mg/kg reduced hydrocarbon dissipation in the rhizosphere of burningbush from 92.48 to 79.44%. Burningbush and maize demonstrated considerable remediation ability over the course of experiment, with slightly higher effectiveness for burningbush both in amended and in unamended soils. Results indicated that high tolerance and biomass establishment of a given plant species in gasoline-contaminated soil, as observed for burningbush and maize, may imply promising phytoremediation performance.

Transport and biodegradation modeling of gasoline spills in soil–aquifer system

The leakage from the oil pipeline and storage tank could get into soil and groundwater and lead to contamination. An understanding of the fate of gasoline spills in soil and groundwater is necessary for designing better monitoring systems and remediation strategies. In this paper, the numerical simulation method for the transport and biodegradation of gasoline spills was built by combining Hydrocarbon Spill Screening Model (HSSM) in vadose zone and modified MT3DMS (a Modular Three-Dimensional Multispecies Transport Model) in saturated zone. First, sensitivity analysis of the required time for gasoline through vadose zone was performed. Then, a three-dimensional soil–aquifer system contaminated by a gasoline spill was simulated, the vertical migration and dissolution of gasoline in vadose zone was analyzed by HSSM, and the transport and biodegradation of dissolved benzene in groundwater was computed by modified MT3DMS. The results demonstrate that the transport and biodegradation of gasoline in soil–aquifer system could be simulated by combining HSSM and modified MT3DMS. The sensitivity analysis shows that (1) if the leakage rate is much higher, the required time of gasoline through vadose zone is much shorter, and that (2) if water saturation is much higher, the required time of gasoline through vadose zone is also much shorter. The results for three-dimensional soil–aquifer system show that: (1) Vertical migration of gasoline takes 10.9 days to pass through the 5-m-high vadose zone; (2) the area of oil lens on the groundwater table enlarges about 31 times than that of source in land surface; (3) there are 94.7 % of the total mass of gasoline spills intercepted by vadose zone, and 27 % of the total mass of benzene enters and pollutes more groundwater; and (4) the microbes could grow and propagate rapidly at the place where dissolved benzene and DO (dissolved oxygen) are enough, and the contaminant plumes of dissolved benzene focus on the vicinity of groundwater table.

Microbial degradation of gasoline in soil: Effect of season of sampling

In cases where fire debris contains soil, microorganisms can rapidly and irreversibly alter the chemical composition of any ignitable liquid residue that may be present. In this study, differences in microbial degradation due to the season in which the sample is collected was examined. Soil samples were collected from the same site during Fall, Winter, Spring and Summer and the degradation of gasoline was monitored over 30 days. Predominant viable bacterial populations enumerated using real-time PCR and reverse transcriptase polymerase chain reaction (RT-PCR) enumeration revealed the predominant viable bacterial genera to be Alcaligenes, Bacillus, and Flavobacterium. Overall, the compounds most vulnerable to microbial degradation are the n-alkanes, followed by the mono-substituted alkylbenzenes (e.g., toluene, ethylbenzene, propylbenzene and isopropylbenzene). Benzaldehyde (a degradation product of toluene) was also identified as a marker for the extent of biodegradation. Ultimately, it was determined that soil collected during an unusually hot and dry summer exhibited the least degradation with little to no change in gasoline for up to 4 days, readily detectable n-alkanes for up to 7 days and relatively high levels of resilient compounds such as o-xylene, p-xylene and 1,3,5-trimethylbenzene. These results demonstrate, however, that prompt preservation and/or analysis of soil evidence is required in order to properly classify an ignitable liquid residue.

Microbial Degradation of Gasoline in Soil: Comparison by Soil Type

During the investigation of a suspicious fire, debris is often collected from the scene and analyzed for residues of ignitable liquids (e.g., gasoline). In cases where the debris is contaminated with soil, it is known that heterotrophic soil microorganisms can alter the chemical composition of the ignitable liquid residue over time. The effects of soil type and season upon this phenomenon are not known, however. Hence, soil collected from locations under three different uses (residential, agricultural, brownfield) were spiked with gasoline and microbial degradation was monitored for 30 days. The soils were also chemically and biologically characterized. Gas chromatographic profiles showed that residential soil was most active and brownfield soil least active for the microbial degradation of gasoline. The brownfield soil possessed relatively high (497 mg/kg) concentrations of Pb, which may have affected bacterial activity. Predominant viable bacterial populations enumerated using real-time reverse transcriptase polymerase chain reaction (RT-PCR) included members of the Alcaligenes, Acinetobacter, Arthrobacter, Bacillus, Flavobacterium, and Pseudomonas genera. Principal Components Analysis (PCA) was found effective in elucidating trends of microbial degradation among the different soil types and seasons. The results of this study demonstrate the necessity of prompt analysis of forensic evidence for proper identification of possible ignitable liquids.

Determining a Bioventing Scale-Up Factor

Bioventing is an increasingly popular means of removing hazardous petroleum products from sites contaminated by industry and underground gasoline storage tanks. A mesoscale bioventing reactor system was used to determine the rate of bioremediation and compared to previous work completed on smaller scale reactors. Ten 4kg reactors with two different soil types were spiked with synthetic gasoline to an initial concentration of 4000mg/kg soil. Vacuum was then applied at a rate of 1mL/min, with sufficient water levels monitored and maintained to induce bioventing conditions. Gas chromatography was used to determine concentrations of synthetic gasoline in soil every two days for each soil type. Results indicate a smaller scale up factor for sandy soils (Delhi), than for clayey soils (Elora). Furthermore it was observed that slower decay rates exist as reactor size increases, suggesting that conservative estimates are needed when transferring lab results to the field.

Volatilization properties of gasoline components in soils

Understanding the volatilization properties of gasoline components in soils is of fundamental importance in the field of geoenvironments. A series of experiments were performed to investigate the effects of temperature, soil water content, soil organic matter content, as well as mean particle size on volatilization rate of total petroleum hydrocarbons (TPH) and the paraffin (n-paraffin and isoparaffin), olefin, naphthene, and aromatic (PONA) components in four typical Japanese soils. The results of this study can be summarized as follows. (1) Volatilization rate of gasoline in a soil is concentration-dependent; extensive volatilization occurs above a certain threshold, while volatilization becomes very slow below this threshold. (2) Compared to other factors, temperature and soil organic matter content have greater effects on volatilization rate of gasoline in soils. The volatilization rate is proportional to temperature, but inversely related to soil organic matter content. (3) The characteristics of time-dependent decreases of TPH and PONA components in soils are similar. The volatilization rate of olefin is higher than those of other components. In addition, volatilization of olefin is also more sensitive to temperature as well as organic matter content.

Studies on the Volatilization of Oil in Soils under Natural Conditions

Oil-contaminated pillars were prepared by spilling oil on soils’ surface. The weight loss of oil was determined by subtracting the pillars’ pre and post weight measured on an electronic balance. The aim of this paper was to investigate the change of oil’s volatilization mass in soils with time. The results show that the gasoline in soils volatilizes at a logarithmic rate with respect to time, and the diesel oil in soils volatilizes at a rate which can be best modelled as a linear of time. The volatilization coefficient of gasoline in grit exceeds that in loam, while the volatilization coefficient of diesel oil in loam is from 2.0 to 2.5 times higher than that in grit. Oils’ volatilization coefficients increase with the increase of oil content. Linear equation and binomial equation describe the relationships of gasoline’s and diesel oil’s volatilization coefficients with oil content respectively.

Enhancing Bioremediation of Diesel Oil and Gasoline in Soil Amended with an Agroindustry Sludge

This paper presents a study of the bioremediation of diesel oil and gasoline by a series of controlled laboratory tests. Sludge from an agroindustry was used to enhance biore-mediation of both gasoline and diesel oil mixed with a soil mass to compare its efficiency with that of a mineral fertilizer. Effects of soil microbiology and soil mixtures were investigated by means of evolution of CO2, micro-organism populations at 90 days, pH at 65 and 95 days, mineral nitrogen, and gas chromatographic analysis of the benzene, toluene, methyl tertiary butyl ether, C8, and C9+total aromatics at the end of the experiments. Treatments containing sludge showed better soil conditions after 170 days of treatment (inorganic nitrogen and microbiota activity) compared with gasoline and diesel oil without amendments. Samples had no detectable traces of the measured hydrocarbons at 170 days of treatment.

Detection of the Engine Anti-Knock Additive Methylcyclopentadienyl Manganese Tricarbonyl (MMT) from Unleaded Gasoline in Soil by Diffuse Reflectance Infrared Fourier Transform Spectroscopy and Mass Spectrometry

Soil samples were washed with dilute solutions of the toxic anti-knock fuel additive methylcyclopentadienyl manganese tricarbonyl (MMT) in hexanes and commercial unleaded gasoline. Diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) was then used to detect the v(CO) modes of MMT, and subsequently 13CO-enriched MMT, in the soil samples. The presence of MMT in the soils was further confirmed by mass spectrometry. Concentrations corresponding to ∼10 ppm Mn in soil could be detected by DRIFTS of the dry samples, and, most interestingly, there was no evidence of significant MMT decomposition over a period of eight months. Apparently, MMT is stabilized by physisorption onto the soils. In the absence of such stabilization, however, MMT undergoes photolytic and thermal decomposition in a matter of minutes. These results suggest the possibility of longer-term environmental problems associated with gasoline spills containing MMT than was previously suspected.

Microbial Degradation of Gasoline in Soil

Abstract Forensic science analysis of soil samples for the presence of flammable liquids occasionally results in the detection of volatile mixtures that lack some of the diagnostic features of common petroleum products. The presence of these mixtures is not consistent with evaporation or with a chemical or physical process, but is reported in microbiological literature that addresses bacterial degradation. Microbiological research has shown that crude oil spilled in the environment is sometimes degraded by bacteria. A study was conducted to demonstrate how automotive gasoline is degraded. Gasoline was spiked into 36 containers of soil (12 were stored at −5°C; 12 were stored at room temperature; and 12 of the soil samples were sterilized prior to the addition of the gasoline and were then stored at room temperature). These samples were monitored, and the results were compared using static heated headspace sampling and capillary gas chromatography. The gasoline in the unsterilized samples stored at room temperature degraded rapidly, while the gasoline in the other two sets of samples was unaffected. This degradation followed trends that can be recognized in casework and can assist in the identification of affected petroleum product residues in soil.

Sensing of Petrochemical Fuels in Soils Using Headspace Analysis with Photoionization-Ion Mobility Spectrometry

Abstract Photoionization-Ion Mobility Spectrometry (PI-IMS) was used to distinguish among common petrochemical fuels including leaded gasoline, unleaded gasoline, kerosene, and diesel fuel through sampling of headpsace vapors over liquid samples. Positive ion mobility spectra obtained in air at ambient pressure were comprised of 3 to 5 peaks which were tentatively identified as benzene, alkylated benzenes, naphthalene and alkylated naphthalenes. The simple mobility spectra from PI-IMS analysis, due to selective ionization of aromatic hydrocarbons. were contrasted with the complex chromatographic patterns for the same fuels from scanning GC/MS analysis. Discrimination between unleaded gasoline and diesel fuel in fuel mixtures was possible using PI-IMS across a broad range of gas-phase concentration ratios. Fuels were also detected in soil using PI-IMS analysis of headspace vapors at 25[ddot]C. Unleaded gasoline in soil was detected from 0.16 to 16 mg/kg for only 0.1 g of sample with nearly linear response. Reproducibility in preparation and analysis of soil samples was 10 to 60% RSD for individual components while instrumental PI-IMS reproducibility with toluene alone was 5% RSD. Water vapor had no effect on PI-IMS response for fuel vapors alone, but increased moisture content in soils caused enhanced response. Drilling mud from a natural gas reserve pit was used to demonstrate environmental application of PI-IMS in sensing a water-saturated sample. Qualitative inspection of results showed no serious complication to PI-IMS response from water. Effects on sensor sensitivity from weathering and other environmental alterations of fuels in soils and groundwater were not explored.