Lower Total Petroleum Hydrocarbon Research Articles

Changes in hydrocarbon groups, soil ecotoxicity and microbiology along horizontal and vertical contamination gradients in an old landfarming field for oil refinery waste

Horizontal and vertical contaminant gradients in an old landfarming field for oil refinery waste were characterised with the aim to assess parallel changes in hydrocarbon groups and general, microbiological and ecotoxicological soil characteristics. In the surface soil polar compounds were the most prevalent fraction of heptane-extractable hydrocarbons, superseding GC–FID-resolvable and high-molar-mass aliphatics and aromatics, but there was no indication of their relatively higher mobility or toxicity. The size of the polar fraction correlated poorly with soil physical, chemical and microbiological properties, which were better explained by the total heptane-extractable and total petroleum hydrocarbons (TPH). Deleterious effects on soil microbiology in situ were observed at surprisingly low TPH concentrations (0.3%). Due to the accumulation of polar and complexed degradation products, TPH seems an insufficient measure to assess the quality and monitor the remediation of soil with weathered hydrocarbon contamination.

Chemical signatures of the Anthropocene in the Clyde estuary, UK: sediment-hosted Pb, 207/206 Pb, total petroleum hydrocarbon, polyaromatic hydrocarbon and polychlorinated biphenyl pollution records

The sediment concentrations of total petroleum hydrocarbons (TPHs), polyaromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), Pb and (207/206)Pb isotope ratios were measured in seven cores from the middle Clyde estuary (Scotland, UK) with an aim of tracking the late Anthropocene. Concentrations of TPHs ranged from 34 to 4386 mg kg(-1), total PAHs from 19 to 16,163 μg kg(-1) and total PCBs between less than 4.3 to 1217 μg kg(-1). Inventories, distributions and isomeric ratios of the organic pollutants were used to reconstruct pollutant histories. Pre-Industrial Revolution and modern non-polluted sediments were characterized by low TPH and PAH values as well as high relative abundance of biogenic-sourced phenanthrene and naphthalene. The increasing industrialization of the Clyde gave rise to elevated PAH concentrations and PAH isomeric ratios characteristic of both grass/wood/coal and petroleum and combustion (specifically petroleum combustion). Overall, PAHs had the longest history of any of the organic contaminants. Increasing TPH concentrations and a concomitant decline in PAHs mirrored the lessening of coal use and increasing reliance on petroleum fuels from about the 1950s. Thereafter, declining hydrocarbon pollution was followed by the onset (1950s), peak (1965-1977) and decline (post-1980s) in total PCB concentrations. Lead concentrations ranged from 6 to 631 mg kg(-1), while (207/206)Pb isotope ratios spanned 0.838-0.876, indicative of various proportions of 'background', British ore/coal and Broken Hill type petrol/industrial lead. A chronology was established using published Pb isotope data for aerosol-derived Pb and applied to the cores.

Biodegradation of semi- and non-volatile petroleum hydrocarbons in aged, contaminated soils from a sub-Arctic site: Laboratory pilot-scale experiments at site temperatures

This study evaluates the feasibility of landfarming biotreatment of petroleum-contaminated soils obtained from a sub-Arctic site at Resolution Island, Nunavut, Canada, and evaluates the changes in composition of the semi- and non-volatile petroleum hydrocarbon fractions during the biotreatment. Pilot-scale landfarming experiments were conducted in a laboratory in soil tanks under temperature profiles representative of the 3-year site air temperatures in July and August where temperature varied uniformly between 1 °C and 10 °C over 10 d. The site soils were acidic and N-deficient, but contained indigenous populations of hydrocarbon-degrading microorganisms. Biostimulation with nitrogen and phosphorus nutrient amendments to achieve C TPH:N:P molar ratio of 100:9:1, and CaCO 3 amendment at 2000 mg Kg −1 for maintaining neutral pH, and periodic 10-day tilling, reduced total petroleum hydrocarbon (TPH) concentrations by up to 64% over a 60-day period. The rate and extent of semi-volatile (F2: >C10–C16) and non-volatile (F3: >C16–C34) petroleum hydrocarbon fractions in the landfarms containing higher initial TPH levels (∼2000 mg Kg −1) and lower TPH levels (∼1000 mg Kg −1) were compared. Significant biodegradation of the F2 and F3 fractions occurred in both of those systems. First-order biodegradation rate constants of up to 0.019 ± 0.001 d −1 were determined for the F3 hydrocarbon fraction and were similar to the F2 fraction biodegradation rate constants of up to 0.024 ± 0.005 d −1. Biodegradation profiles of the C14, C16 and C18 alkanes revealed that at TPH concentrations above 1000 mg Kg −1 these compounds are degraded concurrently, whereas below 1000 mg Kg −1 the higher-molecular weight alkanes are preferentially degraded. After the 60-day treatment period, the TPH concentration was approximately 500 mg Kg −1, and the residual TPH mass was largely associated with particles and aggregated particles with diameters of 0.6–2 mm, rather than the larger or finer particles and aggregates.

Spatial trends of petroleum hydrocarbons in water and sediments

AbstractSeasonal changes in petroleum hydrocarbons in water and streambed sediment from selected oil-related areas of Ondo State, Nigeria have been examined using gravimetric and infrared methods. The highest and lowest total petroleum hydrocarbon concentrations (TPH) in water (sediments in brackets) gravimetrically were 3.49 mg L−1 (199.3) mg kg−1 and 0.003 mg L−1 (81.0) mg kg−1 while the concentrations found by IR were 24.0 mg L−1 (135.0 mg kg−1) and 14.0 mg L−1 (33.0 mg kg−1) respectively. The two seasons were positively correlated (α = 0.01) by both methods. The TPH level was well correlated with the sediment organic carbon (OC) during both seasons. The characteristic carbonyl (C=O) vibrations at 1650 cm−1 and 1700 cm−1 indicate oxidation of the oil residue. The study recommends further investigation into the type of organics present to evaluate their toxicity and appropriate remediation.

Measurement uncertainty in the determination of total petroleum hydrocarbons (TPH) in soil by GC-FID

In this investigation two methods were used for estimating the measurement uncertainty due to sampling and analysis of petroleum hydrocarbon contaminated soil. Analysis of variance (ANOVA) was used for type A evaluation of the measurement uncertainty. The results showed that the statistical evaluation of measurement uncertainty can be complicated by the log-normality and heteroscedasticity of the data. Although mathematical transformation of raw data is widely suggested for overcoming the discrepancy between data and ANOVA assumptions, its use results in problems with the interpretation of the ANOVA results at the original scale. The measurement uncertainty was also estimated from the calculated precision equations for sampling and analysis. Comparison of measurement uncertainty values with the equivalent values obtained with ANOVA revealed that ANOVA overestimates the expanded uncertainty at both low and high TPH concentrations. Consequently, correct selection of the statistical analysis method needs comprehensive knowledge of the assumptions and limitations of statistical methods and careful consideration of the special characteristics (distribution, constancy of measurement variance) of the raw data as these may affect the validity of the estimated uncertainty. The expanded uncertainty obtained in this study for the results of TPH determinations with linear measurement precision modelling was moderate, ranging from 21% at a TPH concentration of 895 mg/kg to 9% at a TPH concentration of 10 019 mg/kg. If a single sample taken in a survey is analyzed only once, then the analytical variance contributes the most to the measurement variance, ranging from 68– 80% at a TPH concentration of 100–10 000 mg/kg.

Microbial Activity and Community Composition during Bioremediation of Diesel-Oil-Contaminated Soil: Effects of Hydrocarbon Concentration, Fertilizers, and Incubation Time

We investigated the influence of three factors-diesel oil concentration [2500, 5000, 10,000, 20,000 mg total petroleum hydrocarbons (TPH) kg(-1) soil], biostimulation (unfertilized, inorganic fertilization with NPK nutrients, or oleophilic fertilization with Inipol EAP22), and incubation time-on hydrocarbon removal, enzyme activity (lipase), and microbial community structure [phospholipid fatty acids (PLFA)] in a laboratory soil bioremediation treatment. Fertilization enhanced TPH removal and lipase activity significantly (P < or = 0.001). The higher the initial contamination, the more marked was the effect of fertilization. Differences between the two fertilizers were not significant (P > 0.05). Microbial communities, as assessed by PLFA patterns, were primarily influenced by the TPH content, followed by fertilization, and the interaction of these two factors, whereas incubation time was of minor importance. This was demonstrated by three-factorial analysis of variance and multidimensional scaling analysis. Low TPH content had no significant effect on soil microbial community, independent of the treatment. High TPH content generally resulted in increased PLFA concentrations, whereby a significant increase in microbial biomass with time was only observed with inorganic fertilization, whereas oleophilic fertilization (Inipol EAP22) tended to inhibit microbial activity and to reduce PLFA contents with time. Among bacteria, PLFA indicative of the Gram-negative population were significantly (P < or = 0.05) increased in soil samples containing high amounts of diesel oil and fertilized with NPK after 21-38 days of incubation at 20 degrees C. The Gram-positive population was not significantly influenced by TPH content or biostimulation treatment.

Heritability of Phytoremediation Potential for the Alfalfa CultivarRiley in Petroleum Contaminated Soil

Petroleum contamination poses a significant threat to environmental ecosystems world-wide. Phytoremediation can be used to enhance degradation of petroleum contaminants in soil. However, selection of plants for phytoremediation has proven to be complicated. This research examines the heritability of the alfalfa cultivar Riley for phytoremediation based on parental total petroleum hydrocarbon (TPH) degradation after twelve months of growth. Traits other than degradation potential, such as root and shoot yield, height, and maturity, were examined for use as selection traits. Riley showed moderate to low heritability that suggests the possibility of breeding for phytoremediation efficiency. In addition, root and shoot yield were found to correlate to TPH degradation. Crosses in which the female parent was typically associated with low TPH dissipation yielded progeny that were high efficiency TPH degraders.

Degradation of Crude Oil in the Rhizosphere of Sorghum bicolor

Dissipation of petroleum contaminants in the rhizosphere is likely the result of enhanced microbial degradation. Plant roots may encourage rhizosphere microbial activity through exudation of nutrients and by providing channels for increased water flow and gas diffusion. Phytoremediation of crude oil in soil was examined in this study using carefully selected plant species monitored over specific plant growth stages. Four sorghum (Sorghum bicolor L.) genotypes with differing root characteristics and levels of exudation were established in a sandy loam soil contaminated with 2700 mg crude oil/kg soil. Soils were sampled at three stages of plant growth: five leaf, flowering, and maturity. All vegetated treatments were associated with higher remediation efficiency, resulting in significantly lower total petroleum hydrocarbon concentrations than unvegetated controls. A relationship between root exudation and bioremediation efficiency was not apparent for these genotypes, although the presence of all sorghum genotypes resulted in significant removal of crude oil from the impacted soil.

Naked Amoebas and Bacteria in an Oil-Impacted Salt Marsh Community.

Populations of soil amoebas were monitored in two salt marshes in Staten Island, NY for 2 years. One site, Gulfport Reach on the Arthur Kill, has been highly impacted by numerous oil spills. In particular, in 1990 a massive no. 2 fuel oil spill from a ruptured pipe flooded the area; its sediments had total petroleum hydrocarbon (TPH) concentrations in the range 800-46,000 ppm. A reference site 11 km away, on the Atlantic coast, had low TPH levels. Amoeba population densities were in general higher in the impacted sediments. In laboratory microcosm experiments, sediment samples from unimpacted sites were treated with added fresh (unweathered) hydrocarbons (no. 2 fuel oil) and cultured; these also yielded higher amoeba numbers than untreated controls. Four distinct amoeba morphotypes were monitored. Changes in population levels of total amoebas were correlated in the two sites, particularly for morphotype 2 (r = 0.83). The ratios of total amoebas to total bacterial numbers were also correlated (r = 0.85) between the sites. This suggests the amoebas may function as generalists, and that their trophic relation to bacterial prey is not much affected by the presence of petroleum hydrocarbons, but rather may reflect regional parameters such as ambient temperature or other physical factors.