Total Petroleum Hydrocarbon Fractions Research Articles

Ecotoxicological environmental risk limits for total petroleum hydrocarbons on the basis of internal lipid concentrations

A method is described for deriving ecotoxicological environmental risk limits (ERLs) for total petroleum hydrocarbons (TPH). Toxicity data for two oil types (light and heavy) to benthic organisms and corresponding estimated internal lipid concentrations, calculated by equilibrium partitioning, are used as a measure of toxicity by narcosis. It is assumed that uptake by organisms takes place from the aqueous phase, and for partitioning, both oil droplets or coating and organic carbon of sediment are taken into account. To distinguish between the different fractions of TPH, the method used is based on a fraction analysis approach in which aliphatic and aromatic compounds are regarded separately and both are further divided into different fractions. A toxic unit approach is applied to these fractions to take additivity into account. Lethality of the lighter oil type (internal concentration 28-204 mmol/Llipid) was in good agreement with data on internal concentrations retrieved from the literature. For the heavier oil type the observed toxicity was slightly higher and can probably be attributed to physical soiling of the organisms by oil or oxygen depletion due to biodegradation of the oil. For deriving ERLs, chronic endpoints are considered. The most sensitive chronic endpoints appear to be similar for both types of oil. The distribution of estimated total internal concentrations for chronic endpoints (1.38-149 mmol/Llipid) is used as a basis for the ERLs. The resulting ERLs for the mixture of TPH are comparable with ERLs for single compounds.

An Improved Gravimetric Method to Determine Total Petroleum Hydrocarbons in Contaminated Soils

A gravimetric method to determine heavy fractions of total petroleum hydrocarbons (TPH) in soils is reported. The method was adapted and calibrated by modifying previous standard methods published, incorporating energy and cost savings where possible. Artificially contaminated soils with different organic matter content, and aged in stationary mode for a period of 8 months were used for calibration. Insufficient solvent evaporation was identified as the most prevalent and largest positive interference in the gravimetric detection. To overcome this, while minimizing the need for heating, a combination of three 10-min rotary evaporator steps and 30 min of vacuum in a desiccator were applied, for a total solvent volume of 60 ml. Hexane was chosen as the extraction solvent and a 40–60 min treatment in an ultrasound bath of 260 W was found suitable to extract 80–95% of TPH extracted by the Soxhlet method. Finally, the use of silica gel for cleanup of co-extracted natural organic matter was found unnecessary, because of the low amounts co-extracted for soils with up to 5% organic carbon, and because the chemical nature of the co-extracted organic matter prevents its selective adsorption to silica.

A multi-process phytoremediation system for decontamination of persistent total petroleum hydrocarbons (TPHs) from soils

Multiple techniques that affect different aspects of contaminant removal can improve remediation of persistent hydrocarbons from soils. We have developed a multi-process phytoremediation system (MPPS) that is composed of land-farming (aeration and light exposure), contaminant degrading bacteria, plant-growth-promoting rhizobacteria (PGPR), and growth of the contaminant-tolerant plant, Tall Fescue ( Festuca arundinacea). In this study, the MPPS was applied to a contaminated soil acquired from the Imperial Oil land farm site in Sarnia, Ontario, Canada. This soil was contaminated with oil refinery sludge to a level of approximately 5% (w/w) total petroleum hydrocarbons (TPHs). Over an initial 4-month period, the average efficiency of removal of persistent TPHs by the MPPS was twice that of land-farming alone, 50% more than bioremediation alone, and 45% more than phytoremediation alone. Importantly, the MPPS removed oil fractions 2, 3 and 4 with equal efficiency. Therefore, the highly hydrophobic, recalcitrant TPH fractions were remediated from the soil with the MPPS. After a second 4-month period, the MPPS removed 90% of all fractions of TPHs from the soil. Phytoremediation alone was able to remove only about 50% of TPHs in the same time period. The key elements for successful phytoremediation were the use of a plant species that can proliferate in the presence of high levels of contaminants, and strains of PGPR that increase plant tolerance and accelerate plant growth in heavily contaminated soils.

Comparative bioremediation of soils contaminated with diesel oil by natural attenuation, biostimulation and bioaugmentation

Bioremediation of diesel oil in soil can occur by natural attenuation, or treated by biostimulation or bioaugmentation. In this study we evaluated all three technologies on the degradation of total petroleum hydrocarbons (TPH) in soil. In addition, the number of diesel-degrading microorganisms present and microbial activity as indexed by the dehydrogenase assay were monitored. Soils contaminated with diesel oil in the field were collected from Long Beach, California, USA and Hong Kong, China. After 12 weeks of incubation, all three treatments showed differing effects on the degradation of light (C 12–C 23) and heavy (C 23–C 40) fractions of TPH in the soil samples. Bioaugmentation of the Long Beach soil showed the greatest degradation in the light (72.7%) and heavy (75.2%) fractions of TPH. Natural attenuation was more effective than biostimulation (addition of nutrients), most notably in the Hong Kong soil. The greatest microbial activity (dehydrogenase activity) was observed with bioaugmentation of the Long Beach soil (3.3-fold) and upon natural attenuation of the Hong Kong sample (4.0-fold). The number of diesel-degrading microorganisms and heterotrophic population was not influenced by the bioremediation treatments. Soil properties and the indigenous soil microbial population affect the degree of biodegradation; hence detailed site specific characterization studies are needed prior to deciding on the proper bioremediation method.

Assessment of intra-species diversity among strains ofAcinetobacterbaumanniiisolated from sites contaminated with petroleum hydrocarbons

A total of 96 crude oil-degrading bacterial strains were isolated from 5 geographically diverse sites in India that were contaminated with different types of petroleum hydrocarbons. The strains were identified by sequencing the genes that encode for 16S rRNA. Out of the 96 isolates, 25 strains were identified as Acinetobacter baumannii and selected for the study. All of the selected strains could degrade the total petroleum hydrocarbon fractions of crude oil. These 25 strains were biochemically profiled and grouped into 8 phenovars on the basis of multivariate analysis of their substrate utilization profiles. PCR-based DNA fingerprinting was performed using intergenic repetitive DNA sequences, which divided the selected 25 strains into 7 specific genomic clusters. tRNA intergenic spacer length polymorphism was performed to determine the intra-species relatedness among these 25 strains. It delineated the strains into 8 genomic groups. The present study detected specific variants among the A. baumannii strains with differential degradation capacities for different fractions of crude oil. This could play a significant role in in situ bioremediation. The study also revealed the impact of environmental factors that cause intra-species diversity within the selected strains of A. baumannii.

Bioremediation of soil contaminated by diesel oil

Were evaluated natural attenuation, biostimulation and bioaugmentation on the degradation of total petroleum hydrocarbons (TPH) in soils contaminated with diesel oil. Bioaugmentation showed the greatest degradation in the light (C12 - C23) fractions (72.7%) and heavy (C23 - C40) fractions of TPH (75.2%) and natural attenuation was more effective than biostimulation. The greatest dehydrogenase activity was observed upon bioaugmentation of the Long Beach soil (3.3-fold) and the natural attenuation of the Hong Kong soil sample (4.0-fold). The number of diesel oil degrading microorganisms and heterotrophic population was not influenced by the bioremediation treatments. The best approach for bioremediation of soil contaminated with diesel oil is the inoculum of microorganisms pre-selected from their own environment.

Source Identification of an Unknown Spilled Oil from Quebec (1998) by Unique Biomarkers and Diagnostic Ratios of “Source-Specific Marker” Compounds

This paper describes a case study in which forensic chemical analyses were conducted to determine the liability for the release of an unknown petroleum product into a river. On June 29th 1998, a fire broke out at a carpet factory in Acton Vale, Quebec. Two months after the fire, there were reports of significant amounts of oil on the surface of the river near the factory. The source of the spilled oil was identified by the standard comparison of the chemical fingerprints of aliphatic, aromatic, biomarker, and total petroleum hydrocarbon fractions, and was further confirmed by determining and comparing the diagnostic ratios of a series of “source-specific marker” compounds, in particular isomers of polycyclic aromatic hydrocarbons (PAHs) and alkylated series of PAHs within the same alkylation groups. Furthermore, an unusually high abundance of the biomarker compound C30 βα hopane was found in both the suspected source and spill samples. This unique feature is rarely seen in crude oils and refined products. Stable carbon isotopic ratio analyses were also performed. From the chemical fingerprinting and data interpretation results we conclude that (1) the residual oil in the spill samples was a Bunker C type fuel; (2) the oil in the samples collected from the river and from a retention basin in the factory all matched with the oil in the heat exchange equipment near the boiler; (3) the oil collected from the river had been heavily weathered; (4) biodegradation of the oil was evident for the river oil-water samples.