A grass phytoremediation field study was initiated in July 1997 at the site of a former railroad tie facility that used creosote for tie preservation. The site is contaminated with polycyclic aromatic hydrocarbons (PAHs). A test matrix consisting of 36 planted (clover, fescue and rye grasses) and unplanted cells was established. The focus of the study was to evaluate PAH remediation in fertilized plots that were unplanted or seeded with clover, fescue or rye. Samples were collected from a depth of 15 to 21 cm, and the six most prevalent PAHs, acenaphthene, fluorene, phenanthrene, fluoranthene, pyrene and chrysene were quantified. Data from four sampling periods, t=0, 9, 12 and 17 months is presented. At t=9 months, substantial loss of the five lowest molecular weight (LMW) PAHs had occurred, and the loss was attributed to natural attenuation. During the first 9 months, below average precipitation at the site delayed grass root development. Between t=9 and 12 months, above average precipitation was recorded and this appeared to accelerate chrysene removal rates in both the unplanted and planted cells; however, the rate was higher rate in the planted cells. Similarly, fluoranthene and pyrene degradation seemed to be enhanced in the fescue and rye cells. Over the last 8 months of the study, acenaphthene, fluorene and phenanthrene concentrations approached constant, minimum levels suggesting additional removal will be limited. PAH compounds with higher solubility correlated to decreased constituent soil concentrations. Additional sampling was initiated at t=17 months to compare PAH concentrations with depth. This was done because the observed root mass changed significantly with depth. Samples were taken at two additional depths 10 to 15 and 32 to 38 cm. Increased removal of fluoranthene and pyrene was observed in the uppermost zone, suggesting a role for plants in remediation of these 4 ringed PAHs. / Master of Science

Coal tar, coal tar creosote and oily wastes are often present as subsurface contaminants that may migrate below the water table, leaving a widely distributed residual source of contaminants leaching to the ground water. <i>In situ</i> chemical oxidation is a potentially viable technology for the remediation of aquifers contaminated with creosote and coal tars. The oxidant of choice would be flushed through the contaminated area to oxidize aqueous contaminants and enhance the mass transfer of contaminants from the oil phase. A series of batch and column experiments were performed to assess the ability of a chemical oxidizing reagent to oxidize creosote compounds and to increase mass transfer rates. Results from the column experiments were then simulated using a reactive transport model that considered 12 different creosote compounds undergoing dissolution, oxidation and advective-dispersive transport. Three strong chemical oxidizing reagents, Fenton's Reagent, potassium persulfate with ferrous ions, and potassium permanganate were tested with batch experiments to determine their reactivity towards creosote compounds. All three reagents successfully decomposed aqueous creosote compounds and were able to reduce the mass of the monitored creosote compounds within the oil phase. However, both the Fenton's and persulfate reagents required large molar ratios of iron and peroxide because the precipitation of iron continually removed the iron catalyst from the aqueous phase. Fenton's and persulfate reagents could be used in systems that are allowed to become acidic to solubilize the iron, but the cost of adjusting the pH, potential impact on aquifer geochemistry and the short lived free radical reaction make these reagents less practical than KMnO4. KMnO4 oxidizes a wide variety of creosote compound, can be used at very high concentrations, and its concentration will not be reduced significantly as it moves through the zone of contamination. The feasibility of using potassium permanganate as an oxidizing reagent for <i>in situ</i> treatment of creosote residuals was investigated using batch column experiments. Column experiments were conducted at a neutral pH in a carbonate rich sand matrix with creosote at 8 % saturation. The columns were treated intermittently with simulated ground water or KMnO4 dissolved in simulated ground water (8 g/L) for 172 days. Under these experimental conditions the KMnO4 decreased the initial mass of the monitored creosote compounds by 36. 5%, whereas in the control column (no oxidizer) only 3. 9% was removed. To remove all of the monitored creosote compounds from the columns it was calculated that the volume needed would be 40 times less for the KMnO4 solution, compared to flushing alone with simulated ground water. To evaluate the potential effectiveness of <i>in situ</i> chemical oxidation at field sites, numerical model simulations need to incorporate relevant chemical oxidation rates to assess system performance and to provide design guidance. In-depth kinetic studies were performed to determine rate constants and to gain insight into the oxidation of creosote compounds with KMnO4. The study examined the kinetics of the oxidative treatment of a selected group of creosote/coal tar compounds in water using excess potassium permanganate and investigated the correlation between reactivity and physical/chemical properties of the organic pollutants. The oxidation of naphthalene, phenanthrene, chrysene, pyrene, 1-methylnapthalene, 2-methylnaphthalene, acenaphthene, fluorene, carbazole, isopropylbenzene, ethylbenzene and methylbenzene closely followed first-order reaction kinetics, enabling calculation of second-order rate constants. Fluoranthene was only partially oxidized by permanganate and the oxidation of anthracene was too fast to be measured. Biphenyl, dibenzofuran, benzene and tert-butylbenzene failed to react in this study. Comprehensive column experiments complemented by numerical modeling revealed an unequal enhancement of the removal of creosote compounds from the oil phase. For the more readily oxidizable compounds such as pyrene and naphthalene, a significant increase in the mass transfer rates was observed in the oxidation columns, compared to the oxidant free column. For non-oxidizable compounds such as biphenyl and dibenzofuran, an increase in the rate of mass removal was also observed in the oxidation columns, even though their aqueous concentrations were not reduced in the column. This was due to the rapid removal of the more readily oxidizable compounds from the oil, which increases the mole fraction of the non-oxidizable compounds. Thus according to Raoult's Law, the concentration in the aqueous phase becomes closer to its pure phase liquid solubility and its aqueous concentration increases. The most significant result of the experiments is the observed increase in the rate of removal of those compounds that have low aqueous solubilities and are readily oxidized, such as pyrene and fluorene. Compounds that have low aqueous solubilities and are not readily oxidizable, such as chrysene, may still take a long period of time to be removed, but the removal time is greatly reduced with oxidation compared to flushing the area with water alone.

Coal tar, coal tar creosote and oily wastes are often present as subsurface contaminants that may migrate below the water table, leaving a widely distributed residual source of contaminants leaching to the ground water. <i>In situ</i> chemical oxidation is a potentially viable technology for the remediation of aquifers contaminated with creosote and coal tars. The oxidant of choice would be flushed through the contaminated area to oxidize aqueous contaminants and enhance the mass transfer of contaminants from the oil phase. A series of batch and column experiments were performed to assess the ability of a chemical oxidizing reagent to oxidize creosote compounds and to increase mass transfer rates. Results from the column experiments were then simulated using a reactive transport model that considered 12 different creosote compounds undergoing dissolution, oxidation and advective-dispersive transport. Three strong chemical oxidizing reagents, Fenton's Reagent, potassium persulfate with ferrous ions, and potassium permanganate were tested with batch experiments to determine their reactivity towards creosote compounds. All three reagents successfully decomposed aqueous creosote compounds and were able to reduce the mass of the monitored creosote compounds within the oil phase. However, both the Fenton's and persulfate reagents required large molar ratios of iron and peroxide because the precipitation of iron continually removed the iron catalyst from the aqueous phase. Fenton's and persulfate reagents could be used in systems that are allowed to become acidic to solubilize the iron, but the cost of adjusting the pH, potential impact on aquifer geochemistry and the short lived free radical reaction make these reagents less practical than KMnO4. KMnO4 oxidizes a wide variety of creosote compound, can be used at very high concentrations, and its concentration will not be reduced significantly as it moves through the zone of contamination. The feasibility of using potassium permanganate as an oxidizing reagent for <i>in situ</i> treatment of creosote residuals was investigated using batch column experiments. Column experiments were conducted at a neutral pH in a carbonate rich sand matrix with creosote at 8 % saturation. The columns were treated intermittently with simulated ground water or KMnO4 dissolved in simulated ground water (8 g/L) for 172 days. Under these experimental conditions the KMnO4 decreased the initial mass of the monitored creosote compounds by 36. 5%, whereas in the control column (no oxidizer) only 3. 9% was removed. To remove all of the monitored creosote compounds from the columns it was calculated that the volume needed would be 40 times less for the KMnO4 solution, compared to flushing alone with simulated ground water. To evaluate the potential effectiveness of <i>in situ</i> chemical oxidation at field sites, numerical model simulations need to incorporate relevant chemical oxidation rates to assess system performance and to provide design guidance. In-depth kinetic studies were performed to determine rate constants and to gain insight into the oxidation of creosote compounds with KMnO4. The study examined the kinetics of the oxidative treatment of a selected group of creosote/coal tar compounds in water using excess potassium permanganate and investigated the correlation between reactivity and physical/chemical properties of the organic pollutants. The oxidation of naphthalene, phenanthrene, chrysene, pyrene, 1-methylnapthalene, 2-methylnaphthalene, acenaphthene, fluorene, carbazole, isopropylbenzene, ethylbenzene and methylbenzene closely followed first-order reaction kinetics, enabling calculation of second-order rate constants. Fluoranthene was only partially oxidized by permanganate and the oxidation of anthracene was too fast to be measured. Biphenyl, dibenzofuran, benzene and tert-butylbenzene failed to react in this study. Comprehensive column experiments complemented by numerical modeling revealed an unequal enhancement of the removal of creosote compounds from the oil phase. For the more readily oxidizable compounds such as pyrene and naphthalene, a significant increase in the mass transfer rates was observed in the oxidation columns, compared to the oxidant free column. For non-oxidizable compounds such as biphenyl and dibenzofuran, an increase in the rate of mass removal was also observed in the oxidation columns, even though their aqueous concentrations were not reduced in the column. This was due to the rapid removal of the more readily oxidizable compounds from the oil, which increases the mole fraction of the non-oxidizable compounds. Thus according to Raoult's Law, the concentration in the aqueous phase becomes closer to its pure phase liquid solubility and its aqueous concentration increases. The most significant result of the experiments is the observed increase in the rate of removal of those compounds that have low aqueous solubilities and are readily oxidized, such as pyrene and fluorene. Compounds that have low aqueous solubilities and are not readily oxidizable, such as chrysene, may still take a long period of time to be removed, but the removal time is greatly reduced with oxidation compared to flushing the area with water alone.

No description available.

Many local authorities are major polluters and are ignoring each and every rule in the book. Raw sewerage is dumped in to rivers and the Vaal River is already a national health threat. Pollution of land, air and water is a common consequence by large corporations capable of causing harm to humans and other living organisms. Research on the pollution of these key natural resources is required to understand cumulative impacts, so as to take measures of precaution to minimize such pollution and reduce its consequences. Risk Assessments are therefore encouraged to identify and explore in quantitative terms, the types, intensities and likelihood of undesired consequences related to the risk of pollution. This study has identified a potential risk from creosote bleedings at Eskom pole yards and aims to explore the probability of such occurrences cumulatively so as to identify precautionary measures at the forefront of this problem to develop effective contingency plans. Soil samples were collected systematically and analysed for polycyclic aromatic hydrocarbons (PAH), a component of creosote that preserves wood. Studies have indicated that concentrations of this preservative beyond acceptable limits can impact negatively on natural resources especially water and soil. The laboratory analysed data indicates that the soil samples collected from the Howick Pole Yard were contaminated with PAH beyond the threshold values. The severity of the contamination, as determined by the application of the Risk Assessment tool, indicates that mitigation measures are essential. / Thesis (M.Sc.)-University of KwaZulu-Natal, 2008.

During the 1950's and 1960's a railroad yard located in Oneida, Tennessee, was used as a creosote treatment facility for railroad ties. After the cross-ties were treated with creosote, the excess creosote was stored in an holding pond located about 100 feet north of Pine Creek (Fetterolf 1998). In 1990, during a creek modification project, creosote was discovered seeping through the banks of Pine Creek. The creosote had leached through the bottom of the pond and migrated towards the creek. In 1997, the Tennessee Department of Environment and Conservation authorized a remedial strategy prepared by Geraghty & Miller, Inc (Fetterolf 1998). The strategy involved the use of phytoremediation and a previously installed interception trench system. The primary goals of the phytoremediation plan are to stimulate biodegradation and to decrease groundwater flow, thus minimizing the migration of the contaminant into Pine Creek. Poplar trees were selected for the phytoremediation plan and were planted in two sections. The objectives of this report involved analyzing the hydrogeology of the Oneida, Tennessee site and organizing the collected data for the purpose of evaluating the impact of the phytoremediation and interception trench systems on the aquifer. The water level data was used to evaluate water level and hydraulic gradient changes due to evapotranspiration, rainfall, and groundwater extraction. It was obvious from the water level and rainfall comparison plots that the rainfall has a measurable effect on the water table elevation (i.e. groundwater flow). Some areas may be less affected because the coal layer has a tendency to decrease recharge. Meanwhile, the interception trench lowers the water level around the trench. The decrease in head occurs before and after the trench, thus the water level forms a "v-shape" at the trench. This "v-shape" lends to the notion that the hydraulic gradient also slopes towards the trench in both directions. As for the phytoremediation, there was not sufficient evidence to suggest that the water levels were being lowered by evapotranspiration. This was expected since the poplar trees were had only completed their second growing season. GMS MODFLOW was used to predict the effects on the water table due to the phytoremediation and the interception trench systems. The calibrated model did an adequate job in simulating the site when the interception trench was not in operation and the trees were not in their growing season. By using variable recharge in some areas, the results are expected to improve. For example, it is important to know the location of the coal layer so this area can be given a lower recharge value than the other areas in the model. As for the trench model, the simulated heads were much lower than the observed heads, which emphasizes that using wells is not the best method to simulate the interception trench. In the future, a transient model should be used to simulate the site with the trench operation, and the drain package could be used to model the trench itself. Meanwhile, the ET model was a valuable simulation, because it illustrates how effective the poplar trees can be even under conservative conditions. With an assumed root zone of just 3 feet and a maximum potential evapotranspiration rate of 4.6 gallons per day per tree, the majority of the site will experience the dry conditions expected. / Master of Science

A groundwater monitoring study was conducted as part of a comprehensive program to remediate a former wood-preserving site that was contaminated with creosote. Twenty-five multi-level samplers (MLSs) were installed on-site and groundwater samples were collected and tested regularly between March 1998 and July 2000. Nearly one-thousand hybrid poplar trees were planted on-site in 1997 to help contain the groundwater plume and enhance phytoremediation. Ten polycyclic aromatic hydrocarbons (PAHs) were monitored along with several terminal electron acceptors (TEAs) and their reduced end products. The focus of the study was to determine the extent of natural biodegradation in the subsurface and assess the role of the poplar trees in site remediation. Since monitoring began, considerable progress has been made remediating the site and the contaminant plume has been shrinking consistently. PAH levels in the groundwater and soil have been reduced and individual MLSs show consistently decreasing contamination. At this point in the study it cannot be conclusively determined what impact the poplar trees are having on the progressing site remediation. However, there is a wealth of evidence indicating that natural biodegradation is playing a major role in site cleanup. Monitoring of TEAs indicates suggests that there are aerobic zones in the site aquifer, but that reduced conditions exist as well. Dissolved oxygen (DO) was found in many MLS ports, but other ports were devoid of both DO and nitrate and contained large quantities of aqueous Fe(II). Oxygen, nitrate and Fe(III) are being reduced on-site and data suggests that they are being used in the biological oxidation of PAHs. Although laboratory studies document the oxidation of PAHs under sulfate-reducing conditions, high aqueous sulfate values were recorded throughout the site, regardless of the level of contamination. Several possible mechanisms are proposed to explain the coexistence of high sulfate and PAHs in the site aquifer. The system may be redox-buffered by excess solid Fe(III) and Mn(III, IV) oxides. Also, dissimilatory sulfate-reducers are strict anaerobes and oxygen-rich rainwater may be toxic to them. The presence of a layer of coal below land surface creates pyrite oxidation conditions similar to those encountered in conjunction with acid mine drainage. The MLSs most affected by the coal layer have less PAHs and DO, lower pH, and higher sulfate and Fe(II) levels than other wells. The oxidation-reduction status of each MLS, based on oxygen, nitrate and Fe(II) measurements, appears to be closely related to the level of PAH contamination, suggesting that PAHs are the primary substrate being biologically oxidized in the site aquifer. These findings tend to support the general belief that the major limitation to natural biodegradation in subsurface environments is the delivery of adequate supplies of suitable TEAs to contaminated zones. / Master of Science

No description available.

This item was digitized as part of the Million Books Project led by Carnegie Mellon University and supported by grants from the National Science Foundation (NSF). Cornell University coordinated the participation of land-grant and agricultural libraries in providing historical agricultural information for the digitization project; the University of Arizona Libraries, the College of Agriculture and Life Sciences, and the Office of Arid Lands Studies collaborated in the selection and provision of material for the digitization project.

An emplaced source of coal tar creosote within the sandy Borden research aquifer has provided an opportunity to document the long term (5140 days) natural attenuation for this complex mixture. Plumes of dissolved chemicals were produced by the essentially horizontal groundwater flowing at about 9 cm/day. Eleven chemicals were extensively sampled seven times using a monitoring network of ~280 14-point multilevel samplers. A model of source dissolution using Raoult’s Law adequately predicted the dissolution of nine of eleven compounds analysed. Mass transformation has limited the extent of the plumes as groundwater flowed more than 500 m yet the plumes are no longer than 50 m. Phenol and xylenes were removed and naphthalene was attenuated from its maximum extent on day 1357. Some compound plumes reached an apparent steady state and the plumes of other compounds (dibenzofuran and phenanthrene) are expected to continue to expand due to an increasing mass flux and limited degradation potential. Biotransformation is the major process controlling natural attenuation at the site. The greatest organic mass loss is associated with the high solubility compounds. However, the majority of the mass loss for most compounds has occurred in the source zone. Oxygen is the main electron acceptor yet the amount of organics lost cannot be accounted for by aerobic mineralization or partial mineralization alone. After 10 years the source zone was treated with permanganate in situ to reduce the flux of contaminants into the dissolved plume and to permit natural attenuation to further reduce the plume extent. A sufficient mass of permanganate was injected to oxidize ~10% of the residual source. Laboratory experiments demonstrated that eight of ten of the study compounds were readily oxidized by permanganate. Once treated oxidized compounds displayed a reduced plume mass and mass discharge while they migrated through the monitoring network. Once beyond the monitoring network the mass discharge and plume mass of these compounds returned to pre-treatment trends. Non-reactive compounds displayed no significant decrease in mass discharge or plume mass. Overall the partial in situ chemical oxidation of the coal tar creosote source produced no long-term effect on the dissolved plumes emanating from the source.