Showing papers on "Total petroleum hydrocarbon published in 2000"

Evaluation of Phytoremediation for Field-Scale Degradation of Total Petroleum Hydrocarbons

Abstract: Laboratory studies have shown phytoremediation to be a feasible method for remediating surface soils contaminated with organic compounds. Evaluation of this technology in the field is difficult because of the inherent spatial heterogeneity in the hydraulic and chemical properties of the soil. In this study, total petroleum hydrocarbon (TPH) degradation was monitored in a field site with three vegetative treatment plots, and one control plot undergoing natural attenuation. Within each treatment, TPH concentrations were monitored at 20 locations over time to study the phytoremediation potential of the different vegetative treatments. For comparing the performance of these treatments in a quantitative manner, first-order kinetics were assumed to be applicable at the local scale. The degradation rates and the initial contaminant concentrations were treated as spatially correlated random fields. Field-scale behavior was evaluated based on temporal variations of the means and variances of concentrations. Our results indicate the importance of spatial variability for an accurate assessment of phytoremediation in the field. From the degradation rate constants and mean reduction in TPH, rye grass and St. Augustine grass appear to be superior to sorghum and the unvegetated control in reducing contaminant concentrations in the field.

Assessment of the photoenhanced toxicity of a weathered oil to the tidewater silverside

Abstract: Studies were conducted to determine the interactive toxicity of a water-accommodated fraction (WAF) of a weathered middle distillate petroleum and solar radiation to an estuarine organism, the tidewater silverside (Menidia beryllina). Juvenile silversides were monitored for survival and growth during a 7-d static renewal exposure to dilutions of WAFs of an environmentally weathered oil collected in the vicinity of an abandoned oil field in California. Ultraviolet (UV) treatments were based on incident sunlight intensity and spectra measured at this site. Exposure to UV alone was not lethal to the fish, and WAF in the absence of UV was toxic at the highest total petroleum hydrocarbon (TPH) concentration (3.03 mg/L) after 96 h of exposure. Water-accommodated fractions toxicity increased significantly with increasing UV irradiance and duration of exposure. The 7-d LC50 concentrations for the control, low, medium, and high irradiance were 2.84, 1.27, 0.93, and 0.51 mg/L TPH, respectively. Significant mortality occurred among fish previously exposed to WAF in the absence of irradiance, whereas WAF toxicity was unaffected by UV exposure prior to the toxicity test. Thus, the mode of action is a photosensitization of the accumulated petroleum residue rather than a photoactivation of WAF. Chemical analysis indicates that the WAF contains limited amounts of polycyclic aromatic hydrocarbons (PAHs) known to be photoenhanced, suggesting that other constituents may be responsible for the observed photoenhanced toxicity.

Plants‐associated microflora and the remediation of oil‐contaminated soil

Abstract: The use of plants and their rhizospheric microorganisms is a promising emerging technology for remediating contaminated soils. The degradation of total petroleum hydrocarbon (TPH) in the rhizospheric and nonrhizospheric soil of three domestic plants, namely, alfalfa (Medicaga sativa) broad beans (Vicia faba) and ryegrass (Lolium perenne) was investigated. The experimental data from the studies of plantmicrobe‐soil interactions implicated the enhancement of TPH degradation by the rhizospheric microbial community. Although the three domestic plants exhibited normal growth in the presence of ∼1.0% TPH, the degradation was more profound in the case of leguminous plants. The TPH degradation in the soil cultivated with broad beans and alfalfa was 36.6 and 35.8%, respectively, compared with 24% degradation in case of ryegrass. Such a high correlation between plant type and TPH degradation rates indicate that selection for enhanced rhizosphere degradation may be accomplished by selecting leguminous plants.

Toxicity of crude oil and dispersed crude oil to ghost shrimpPalaemon serenus and larvae of Australian bassMacquaria novemaculeata

Abstract: Acute 96-h LC50 values of the water-accommodated fraction (WAF) of crude oil, dispersants (Corexit 9500 and Corexit 9527) and dispersed oil combinations were determined in semistatic bioassays with seawater, using the ghost shrimp Palaemon serenus and larval Australian bass (fish) Macquaria novemaculeata. Sodium dodecyl sulphate (SDS) and zinc sulphate were used as reference toxicants and identical bioassays were conducted using these compounds. Total petroleum hydrocarbon (TPH) uptake of shrimp was also measured on the samples taken from the bioassays. The nominal mean (n=4) 96-h LC50 standard error (SE) values for WAF of crude oil, Corexit 9527, Corexit 9500, dispersed oil (9527) and dispersed oil (9500) were 258,000 ppm (13,000), 49.4 ppm (6.4), 83.1 ppm (5.8), 8.1 ppm (0.3), and 3.6 ppm (0.3) in the shrimp bioassays, respectively. The nominal mean (n=4) 96-h LC50 (SE) values calculated from the fish larval bioassays were 465,000 ppm (16,000), 14.3 ppm (0.9), 19.8 ppm (1.6), 28.5 ppm (1.4), and 14.1 ppm (2.6) for WAF of crude oil, Corexit 9527, Corexit 9500, dispersed oil (9527), and dispersed oil (9500), respectively. These LC50 values indicate that dispersed oil combinations were significantly more toxic to these organisms than WAF of crude oil. TPH uptake of shrimp increased in correlation to exposure concentrations, and the presence of dispersant made oil more available for shrimp. © 2000 John Wiley & Sons, Inc. Environ Toxicol 15: 91–98, 2000

Characterization and source identification of an unknown spilled oil using fingerprinting techniques by GC-MS and GC-FID

Abstract: This article 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. The source of the spilled oil was identified using gas chromatography with mass spectrometry and flame ionization detection by comparing the chemical fingerprints of aliphatic, aromatic, biomarker, and total petroleum hydrocarbon fractions. The source 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. From the chemical fingerprinting and data interpretation results, the authors concluded that the oil spilled was diesel fuel, that the fuel had been only slightly weathered since its spill, that the suspected diesel was clearly demonstrated to be the source of the spilled oil, and that the spilled diesel was relatively fresh and the period since the spill was no more than several days.

Modeling water quality impacts of petroleum contaminated soils in a reservoir catchment

Abstract: Soil contamination due to spills or leaks of crude oils andrefined hydrocarbons is a common problem. Estimation of spillvolume is a crucial issue in order to determine the expectedcontaminating life span of contaminated soils. The directprocedure to determine the amount of hydrocarbon in soil is to measure the concentration of total petroleum hydrocarbon (TPH) in soil samples. The primary objective of this study was toassess the potential effects of oil contaminated soils on thewater quality of Devegecidi dam reservoir. For this purpose,limited spill data available were evaluated and soil samplingstudies were conducted in the Beykan oil field to analyze forTPH on oil contaminated soils. Available spill and measured soilTPH data were used in a subsequent modeling study to assess thereservoir water quality impacts due to dissolved mass leachingfrom hydrocarbon contaminated soils. Evaluation of availablespill data between 1989 and 1995 revealed that a total of 252recorded spills resulted in a net spill of 395 tons. The majortypes of oil spills were identified as well heads (WH), returnlines/flow lines (RL/FL), and power oil lines (POL). A total of211 soil samples was collected at selected well heads andanalyzed for TPH in the laboratory. TPH results revealed aconcentration range between 600 and 115 500 mg kg-1 with a meanconcentration of 20 300 mg kg-1. Modeling studies focused onbehavior assessment and involved two major components. The firstcomponent is a soil-leaching submodel for estimating theleachate concentration and contaminant mass leaching out of thecontaminated soil body. The second component is a reservoirwater quality submodel assuming complete-mix conditions forestimating the changes of hydrocarbon concentration in thereservoir water as a function of time. These two components arecoupled via a mass inflow term present in the reservoir waterquality model, accounting for contaminant mass loadingcontributed by the leaching of contaminated soil. Simulation runs performed under conservative conditions assuming an annualaverage oil spill volume of 95 tons and the minimum reservoirvolume of 7.3 × 106 m3 revealed that there isno imminent threat to reservoir water quality from the dissolved phase contaminants soils. Limited amount of availablemeasurements of TPH concentrations in soil samples and benzeneconcentrations in reservoir water samples supported model results.

A new bioremediation approach in the treatment of petroleum‐contaminated groundwater

Abstract: The objective of this research is to determine the feasibility of enhanced bioremediation with oxygen‐releasing compound (ORC) of petroleum‐contaminated groundwater. Total petroleum hydrocarbon (TPH) and its most important components benzene, toluene, ethylbenzene and xylene (BTEX) may be degraded via biological activities under aerobic conditions. The ORC can supply oxygen when needed, as can other chemical oxygen sources like hydrogen peroxide and calcium peroxide, but the ORC has several important advantages. The concentrations of TPH and BTEX were reduced to almost 99% of the original in the ORC batch due to high microbial activity. In contrast, only a 18.9% reduction of TPH and a 2.1 % reduction of the total BTEX were found in the control batch after two weeks of incubation. It is suggested that this improved biodegradation process, which poses high treatment efficiency in a short period, may be a good approach for field applications such as soil and groundwater remediation.

Evaluation of H.E.L.P. Mate 2000 for the Identification and Quantification of Petroleum Hydrocarbon Products

Abstract: : The H.E.L.P. Mate 2000 (HM 2000) is a spectrophotometric instrument developed for use with the Hanby Test Kits to rapidly assess of total petroleum hydrocarbon contamination (TPH) in environmental matrices on site. This spectrophotometer is designed to remove the subjectivity associated with the present visual method of analysis, and to eliminate the requirement for prior knowledge of the type of petroleum hydrocarbon contamination present at a given site. Both the HM 2000 and the current visual method of analysis measure the color that is produced by the Friedel-Crafts reaction with the aromatic hydrocarbons present in petroleum-based fuels, oils, and solvents. Laboratory and field studies were used to evaluate the HM 2000. Different results were obtained, depending on the type of sample matrix. In general, the HM 2000 was more accurate and precise for soil samples than for water samples. However, in comparison to the visual method, the HM 2000 was neither as accurate nor did it offer any qualitative advantages.

Planting crops on land spread with tank bottoms: a possible disposal solution for oilfields

Abstract: Tank bottoms from a Williston Basin oilfield were applied to test plots in which crops were subsequently planted. Naturally occurring microbes reduced the 6% total petroleum hydrocarbon (TPH) concentration to 3.8% in a few months (a 37% reduction), but reduced it no further, possibly due to an insufficient amount of nitrogen or water or both. For the first three years of the study, the 6% TPH test plot did not grow crops. It was apparent that the high (6%) application rate of this high paraffin oil seriously restricted the infiltration of water into the soil; this is considered to be the primary cause of crop failure, rather than toxicity of the tank bottoms. After manure was applied in the fall of the third year, crops were successfully grown the following season. Two years after that, when the manure had degraded, crop growth was again very poor. The lack of water may have also affected the process of microbial oil degradation. The second phase of the study examined the addition of straw and large amounts of nitrogen and phosphate fertilizer to new test plots. A 0.6% TPH concentration was applied to two test plots which had been previously planted to spring wheat. Because there had been no rain, the crop was poor, and there was concern that the application of oil plus tilling would kill the crop. When it did rain later in the summer, the seed left in the ground germinated and successfully produced a crop. The addition of straw did not increase the chances of crop growth; rather, it reduced the yield of the crop significantly, even with a higher rate of fertilizer application. The original 0.6% TPH concentration was reduced to 0.14% in one year, a 77% reduction, suggesting that lower application rates may remediate faster, in addition to allowing crops to grow. This study suggests that application of low concentrations of tank bottoms on agricultural land may be possible, but additional research is needed to discover how to control the hydrophobic effects of this disposal method. The addition of manure (rather than straw) to land spread with tank bottoms appears to be favorable to plant growth by increasing water infiltration and retention.

Evaluating the Hanby Test Kits for Screening Soil and Groundwater for Total Petroleum Hydrocarbons: Field Demonstration

Abstract: : This report evaluates the methods of analysis that can be used with the Hanby Test Kits for assessing the total petroleum hydrocarbon (TPH) contamination in environmental matrices. This field screening technique is based on the colorimetric analysis of petroleum products in soil and water matrices, following a solvent extraction and a Friedel-Crafts reaction. The methods include visually comparing the sample to reference photographs, and two spectrophotometric (H.E.L.P. Mate 2010 and 2000) systems designed to establish discrete values. To test these field screening techniques, 90 field and quality assurance (QA) samples were obtained. Both of the spectrophotometric methods experienced instrumental problems, so that fewer than 60% of the samples distributed could be analyzed on-site. Ultimately, the H.E.L.P. Mate 2010 was dropped from the evaluation altogether. Furthermore, because of these complications, no TPH values were reported during the field exercise. The results yielded by the visual and H.E.L.P. Mate 2000 methods were compared for the QA samples; the visual technique was more reliable for showing the presence and estimating the quantity of TPH contamination.