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Accidental spills of hydrocarbons from underground storage tanks or pipelines are a common cause of subsurface contamination. Anthropogenic hydrocarbon contamination of soil is a global issue throughout the industrialised world. In England and Wales alone, 12% of all serious contamination incidents in 2007 were hydrocarbon related. Biodegradation could be in situ process leading to a decrease of benzene concentrations in groundwater. Recently, monitored natural attenuation has become an effective alternative to the more active remediation methods for the in situ treatment of contaminated subsurface environments. The main objective of this study was to examine the possibility of adopting monitored natural attenuation as a remediation technique for the contaminated groundwater aquifer. In this natural attenuation study, the following tasks were conducted bioremediation investigation, biological first-order decay rates, Mann-Kendall Test model and BIOSCREEN model for the contaminated groundwater aquifer. In this study, a full-scale natural bioremediation investigation was conducted at a petroleum hydrocarbon spill site. In this study, The calculated biodegradation capacity (8.261 mg/L) at this site is much higher than the detected concentrations of petroleum-hydrocarbons (3-4 mg/L) within the most contaminated area inside the plume. Thus, natural biodegradation should be able to remove the contaminants effectively. The calculated biological first-order decay rates for benzene were between 1.7¡Ñ10-3-9.0¡Ñ10-4 day-1 respectively. Mann-Kendall test was applied to analyze the trend of contaminant variations. Results show that the S-value of monitor wells SW-1W, SW-4W, SW-42W, SW-23W, SW-30W, SW-67W and SW-70W were -2.23607, -1.16276, -1.52053, -1.34164, -1.26323, 0 and -1.34164, respectively. The negative S values reveal that the all contaminants tended to decrease. This indicates that the hydrocarbon plume at this site is not expanding, and has been contained effectively by the natural attenuation mechanisms. BIOSCREEN model from the groundwater analyses indicate, a first-order decay model reached the downgradient monitor well located 220 m from the spill location. that approximately 89% of the contaminate removal was due to biodegradation processes. The study of petroleum-hydrocarbons bacterial consortium were include Aquincola tertiaricarbonis L10¡BBosea sp. GR060219¡BBrachymonas petroleovorans strain CHX¡BHydrogenophaga sp. p3(2011)¡BHydrogenophaga sp.¡BMethylibium sp. YIM 61602¡BMycobacterium sp.¡BRhodoferax sp. IMCC1723¡BRhodoferax sp.¡BUncultured Rhodocyclaceae bacterium clone Elev_16S_975¡BUncultured Rhodocyclaceae bacterium clone eub62B1¤ÎUncultured Beggiatoa sp. clone GE7GXPU01BJTWR. Thus, the in situ bioremediation technology has the potential to be developed into an environmentally, economically and naturally acceptable remediation technology. Evidences for the occurrence of natural attenuation include the following: (1) depletion of dissolved oxygen, nitrate, and sulfate; (2) production of dissolved ferrous iron, sulfide, and CO2; (3) decreased BTEX concentrations and BTEX as carbon to TOC ratio along the transport path; (4) increased alkalinity and microbial species; (5) limited spreading of the BTEX plume; and (6) preferential removal of certain BTEX components along the transport path. Results indicate that natural attenuation can effectively contain the plume, and biodegradation processes played an important role on contaminant removal.

Contamination of groundwater by petroleum-hydrocarbons is a serious environmental problem. Monitored natural attenuation (MNA) is a passive remedial approach to degrade and dissipate contaminants in groundwater. In this study, a full-scale natural bioremediation investigation was conducted at a gasoline spill site. Results show that the concentrations of major contaminants [benzene, toluene, ethylbenzene, and xylenes (BTEX)] dropped to below detection limit before they reached the downgradient monitor well. This indicates that natural biodegradation process was the major cause of the contaminant reduction. In this study, 1,2,4-trimethylbenzene (1,2,4-TMB) was used as tracer to calculate the biological decay rates of BTEX. The calculated biological first-order decay rates for ethylbenzene, m+p-xylene, toluene, benzene, and o-xylene were 1.5¡Ñ10-3, 1.2¡Ñ10-3, 7.0¡Ñ10-4, 6.7¡Ñ10-4, and 1.2¡Ñ10-4, respectively. Mann-Kendall test was applied to analyze the trend of contaminant variations. Results show that the S-value of four monitor wells (CT-4, CT-41, CT-42, and CT-7) were -0.52, -1.57, -0.52, and -1.22, respectively. The negative S values reveal that the all contaminants tended to decrease. This indicates that the hydrocarbon plume at this site is not expanding, and has been contained effectively by the natural attenuation mechanisms. Evidences for the occurrence of natural attenuation include the following: (1) depletion of dissolved oxygen, nitrate, and sulfate; (2) production of dissolved ferrous iron, sulfide, and CO2; (3) decreased BTEX concentrations and BTEX as carbon to TOC ratio along the transport path; (4) increased alkalinity and microbial species; (5) limited spreading of the BTEX plume; and (6) preferential removal of certain BTEX components along the transport path. Results also show that the biodegradation capacity (46.02 mg/L) for BTEX and 1,2,4-TMB was much higher than the detected contaminants within the plume. Results indicate that natural attenuation can effectively contain the plume, and biodegradation processes played an important role on contaminant removal.

Site characterization methods for measuring the occurrence, magnitude, and rate of microbial mediated transformation processes were evaluated to assess the implementation of monitored natural attenuation (MNA) at chlorinated ethenes contaminated sites. A model site in Arizona, the Park-Euclid WQARF site in Tucson, was selected for the study. Field, geochemical, and compound specific carbon isotope fractionation (CSI) data confirm intrinsic biodegradation is occurring in the perched aquifer. Use of the BIOCHLOR model and a screening protocol support the potential for reductive dehalogenation found in the perched aquifer. Biotransformation of tetrachloroethene to cis-1,2-dichloroethene (cis-DCE) was achieved in microcosm studies. Transformation of cis-DCE to vinyl chloride and to ethene is, at the moment, the laboratory rate limiting step. PCR analysis established that the aquifer contains Dehalococcoides sp. and other dechlorinating microorganisms, though genes that encode for enzymes capable of achieving complete dehalogenation of the chlorinated contaminants were confirmed only in one monitoring well. The regional aquifer shows little evidence of intrinsic biodegradation. This study corroborates that CSI analysis can be used as an additional line of evidence to evaluate and verify MNA. Microbial analysis provides relevant information about the capabilities of native microbial communities to carry out reductive dehalogenation and thus, to naturally attenuate chlorinated compounds at a contaminated site. The combination of microcosm studies, CSI analysis, and bacterial DNA identification is becoming a convincing line of evidence for the assessment of MNA application to chloroethenes contaminated sites.

Natural Attenuation Software (NAS) was developed as a screening tool to estimate remediation timeframes for monitored natural attenuation (MNA) to lower groundwater contaminant concentrations to regulatory limits, and to assist in decision-making on the level of source zone treatment in conjunction with MNA using site-specific remediation objectives. In addition, NAS facilitates the combined use of MNA with engineered remedial actions (ERAs) so that the benefits of each technology can be maximized while minimizing costs of remediation. The primary expected benefit of NAS is to increase regulatory acceptance of MNA, thereby decreasing overall remediation costs. NAS is designed for application to ground-water systems consisting of porous, relatively homogeneous, saturated media, and assumes that groundwater flow is uniform and unidirectional. NAS consists of a combination of analytical and numerical solute transport models implemented in three main interactive modules to provide estimates for: (1) target source concentration required for a plume extent to contract to regulatory limits, (2) time required for NAPL contaminants in the source area to attenuate to a predetermined target source concentration, and (3) time required for a plume extent to contract to regulatory limits after source reduction. Natural attenuation processes that NAS models include advection, dispersion, sorption, non-aqueous phase liquid (NAPL) dissolution, and biodegradation. NAS determines redox zonation, and estimates and applies varied biodegradation rates from one redox zone to the next. Recently, NAS was enhanced to include petroleum hydrocarbons, chlorinated ethenes, chlorinated ethanes, chlorinated methanes, and chlorinated benzenes, or any user-defined contaminants (e.g., heavy metals, radioisotopes), and has included the capability to model co-mingled plumes. To enable comparison of remediation timeframe estimates between MNA and specific ERAs, NAS was modified to incorporate an estimation technique for timeframes associated with pump-and-treat remediation technology for comparison to, or in conjunction with, MNA. NAS also expanded analysis tools for improved performance assessment, as well as the assessment of sustainability of natural attenuation processes over time. A Department of Defense (DoD) Environmental Security Technology Certification Program (ESTCP) demonstration was undertaken to evaluate the capability of the NAS software to provide reasonable estimates of MNA cleanup timeframes in a variety of environments and sites throughout the United States. Overall, results suggest that NAS was satisfactory in meeting performance objectives set forth in the demonstration, and that because NAS is based on sound science, it can serve as an effective tool for decision-making and data analysis at a wide range of contaminated sites and is not limited to a small subset of “simple sites” because of its simplicity. At some sites, NAS-estimated timeframes were crucial for winning regulatory acceptance of MNA, with cost-benefit analyses providing estimates of savings associated with using MNA as a final remediation strategy. / Ph. D.

For this study, we revisited whether the common iron Fe mineral, magnetite Fe3O4 (s), can reduce tetrachloroethylene (PCE) and trichloroethylene (TCE) as discrepancies exist in the literature regarding rates and extent of reduction. We measured PCE and TCE reduction in batch reactors as a function of magnetite stoichiometry (x = Fe2+/Fe3+ ratio), solids loading, pH, and Fe(II) concentration. Our results show that magnetite reacts only slowly with TCE (t1/2 = 7.6 years) and is not reactive with PCE over 150 days. The addition of aqueous Fe(II) to magnetite suspensions, however, results in slow, but measurable PCE and TCE reduction under some conditions. The solubility of ferrous hydroxide, Fe(OH)2(s), appears to play an important role in whether magnetite reduces PCE and TCE. In addition, we found that Fe(OH)2(s) reduces PCE and TCE at high Fe(II) concentrations as well. At certain conditions degradation of the PCE and TCE is enhanced by an unexplored synergistic response from magnetite and ferrous hydroxide iron phases. Our work suggests that measuring dissolved Fe(II) concentration and pH may be used as indicators to predict whether PCE and TCE will be abiotically degraded by groundwater aquifer solids containing magnetite.

In a country with continental dimensions like Brazil, road infrastructure that provides a displacement with comfort and safety is extremely important, once it is from these roads that the majority of supplies and people moves daily to distant regions. Is through appropriate management of corrective floors and measurements taken at the correct times that these highways provides safety and comfort to users in their displacement. One way to perform this management properly is making use of performance prediction models that makes the manager can predict the appearance of defects and the necessity of performing maintenance, providing financial resources required for repairs. Thus, the objective of this research is to monitor three highway stretches implemented in the region of Santa Maria - RS, checking their functional and structural performance in order to assist in the development of performance prediction models. To achieving the study, tests were performed at predetermined periods: Sand Patch, British Pendulum, Roughness, Rutting analysis, Distress identification and Deflections Basin Survey by Benkelman Beam and Falling Weight Deflectometer (FWD) at Roraima Avenue (restoration stretch), Hélvio Basso Avenue and Quartéis Intersection (new highway stretches). In these tests, quantitative and classifying counts of vehicles were made in order to find the number of equivalent demand of standard axis through the FEC calculation by AASHTO and USACE methodology. With that was obtained in all 34 performance prediction models for Avenues Roraima and Hélvio Basso (17 - AASHTO and 17 - USACE). No models have been developed for Quartéis Intersection once it is at the beginning of monitoring. In addition to performance prediction models, performance evaluations were carried out of three sections monitored the mediated that it were requested by the traffic, and found that the Roraima Avenue had the highest deflection values, IGG and cracked area. The Quartéis Intersection had the highest values of rutting. Back Analysis were performed by BAKFAA software to obtain resilient modulus in all layers of pavements studied and, in general, met values coherent with those studied in the literature. It was also made structural analysis by AEMC/SisPAv (2009) software in order to find the estimated durability in the highway stretches. The Roraima Avenue despite being an old stretch and present the highest amount of early distress, was the one that had the highest prediction of durability between the three analysed sections. Furthermore, structural analysis was performed for Roraima Avenue, by standard DNER PRO 011/1979, once it is a restored pavement, it was found that this stretch is expected five years and ten months of durability. Therefore, monitoring and obtaining performance prediction models are extremely important for the proper management of pavements. / Em um país com dimensões continentais como o Brasil, infraestrutura de rodovias que proporcione um deslocamento com conforto e segurança é extremamente importante, uma vez que é a partir destas rodovias que a grande maioria dos insumos e das pessoas se desloca diariamente para regiões distantes. É por meio da gerência adequada dos pavimentos e medidas corretivas realizadas nos tempos corretos, que estas rodovias fornecem aos usuários segurança e conforto nos seus deslocamentos. Uma forma de realizar esta gerência de maneira adequada é fazendo uso de modelos de previsão de desempenho, que fazem com que o gestor possa prever de forma antecipada o aparecimento de defeitos e a necessidade da realização de manutenções, disponibilizando, assim, recursos financeiros necessários para as obras de intervenções. Com isso, o objetivo desta pesquisa é realizar o monitoramento de três trechos implantados na região de Santa Maria RS, verificando seus desempenhos funcionais e estruturais de modo a subsidiar a construção de modelos de previsão de desempenho. Para a concretização do estudo foi realizado, em períodos pré-determinados, ensaios de Mancha de Areia, Pêndulo Britânico, Irregularidade Longitudinal, Afundamento em Trilha de Roda, Levantamento Visual de Defeitos e Levantamento de Bacia de Deflexões através da Viga Benkelman e Falling Weight Deflectometer (FWD) na Avenida Roraima (trecho de restauração), Avenida Hélvio Basso e no Trevo dos Quartéis (trechos novos). Além destes ensaios, foram feitas contagens quantitativas e classificatórias dos veículos que solicitavam os trechos, com a intenção de encontrar o número de solicitações equivalentes do eixo padrão através dos cálculos de FEC pela metodologia AASHTO e USACE. Com isso, obteve-se no total 34 modelos de previsão de desempenho para as Avenidas Roraima e Hélvio Basso (17 AASHTO e 17 USACE). Não foram desenvolvidos modelos para o Trevo dos Quartéis, uma vez que o mesmo está em início de monitoramento. Além dos modelos de previsão de desempenho, foram realizadas avaliações do desempenho dos três trechos monitorados à mediada que o mesmo era solicitado pelo tráfego, sendo verificado que a Avenida Roraima apresentou os maiores valores de deflexão, IGG e Área Trincada. Já o Trevo dos Quartéis apresentou os maiores valores de ATR. Foram realizadas retroanálises pelo software BAKFAA para obtenção de módulo de resiliência em todas as camadas dos pavimentos estudados e, de forma geral, encontrou-se valores coerentes com os estudados na literatura. Fez-se, também, análises estruturais através do software AEMC/SisPAv (2009), a fim de encontrar a estimativa de durabilidade dos trechos. A Avenida Roraima apesar de ser um trecho antigo e apresentar a maior quantidade de defeitos prematuramente, foi a que teve a maior previsão de durabilidade entre os três trechos. Além disso, realizou-se a análise estrutural da Avenida Roraima pela norma DNER PRO 011/1979, uma vez que se trata de uma restauração de um pavimento e constatou-se que este trecho tem previsão de durabilidade de cinco anos e dez meses. Assim, o monitoramento e obtenção de modelos de previsão de desempenho são de suma importância para a boa gerência dos pavimentos.

Reductive dechlorination is a significant natural attenuation process in chloroethene-contaminated aquifers where organic carbon combined with reducing redox conditions support active dechlorinating microorganisms. At sites where natural organic carbon (NOC) associated with the aquifer matrix provides fermentable organics, the ability to measure the NOC is needed to assess the potential for the long-term sustainability of reductive dechlorination. This study focused on developing a method to measure the potentially bioavailable organic carbon (PBOC) associated with aquifer sediment. To measure NOC and evaluate its biodegradability, liquid extraction techniques on aquifer sediment were investigated. Single extractions with different extracting solutions showed that extractable organic carbon associated with the sediment ranged from 1-38% of the total organic carbon content (TOCs). Bioassay experiments demonstrated that 30-60% of the extractable organic carbon can be utilized by a microbial consortium. Alternating between 0.1% pyrophosphate and base solutions over multiple extractions increased the rate of removal efficiency and targeted two organic carbon pools. The result of the investigation was a laboratory method to quantify organic carbon from the aquifer matrix in terms of the PBOC. In the second part, the extractable PBOC was shown to biodegrade under anaerobic conditions, to produce H2 at levels necessary to maintain reductive dechlorination, and to support reductive dechlorination in enrichment cultures. For the third part of the research, the difference in extractable organic carbon inside and outside of a chloroethene-contaminated plume was examined through the combination of PBOC laboratory data and field parameters. Supported by ground-water constituent data, the PBOC extraction and bioassay studies showed that less extractable organic carbon was present inside than outside of the chloroethene plume. The final part of the research investigated the distribution of PBOC extractions across six contaminated sites. PBOC extractions were directly correlated to the TOCs, soft carbon content, and level of reductive dechlorination activity at the sites. Based on these correlations, a range for organic carbon potentially available to subsurface microorganisms was proposed where the upper bound consisted of the soft carbon and the lower bound consisted of the PBOC. / Ph. D.

Groundwater remediation strategies have advanced toward more effective and economical remedial technologies. Monitored natural attenuation (MNA) has become accepted by federal regulatory agencies as a viable remediation strategy for contaminants under site-specific conditions. At chloroethene contaminated sites where MNA is used as a remediation strategy, microbially-mediated reductive dechlorination is typically the dominant pathway for natural attenuation. The efficacy of reductive dechlorination at sites with no anthropogenic carbon sources is often influenced by the availability of readily-biodegradable natural organic carbon along with favorable geochemical conditions for supporting microbial dehalogenation. Recent research studies have suggested that the pool of labile natural organic carbon, operationally defined as potentially bioavailable organic carbon (PBOC), may be a critical component related to sustaining reductive dechlorination at MNA sites. The objective of this study was to evaluate PBOC as a quantitative measure of the labile organic carbon fraction of aquifer sediments in relation to microbial reductive dechlorination of chlorinated solvents. In the first phase of this study, the variability of PBOC in aquifer sediments was examined among 15 chloroethene contaminated sites. Results showed that PBOC displayed considerable variability among the study sites, ranging over four orders of magnitude. Regression results demonstrated that a positive correlation existed between PBOC, solid phase total organic carbon (TOCs), and reductive dechlorination activity at the sites. Results supported that greater levels of PBOC and TOCs corresponded to higher reductive dechlorination activity at the sites. Composition results showed that 6-86% of PBOC consisted of proteins and amino acids. Results also suggested a positive relationship existed between PBOC, concentrations of potentially bioavailable organic compounds present in the aquifer system, expressed as hydrolyzable amino acids (HAA), and the natural attenuation capacity (NAC) at the sites. Higher PBOC levels were consistently observed at sites with greater NAC and levels of HAA. The results of this study suggested that the variability of PBOC in the aquifer sediments exhibited a reasonable correlation with TOCs, hydrolyzable amino acids, and chloroethene transformation among the selected sites. In the second phase of this study, the relationship between PBOC in aquifer sediments and site specific performance data was evaluated among 12 chloroethene contaminated sites. Results demonstrated that PBOC in aquifer sediments was directly correlated to independent field metrics associated with reductive dechlorination. Levels of PBOC demonstrated direct relationships with hydrogen (H2) and dissolved oxygen (DO) concentrations within the groundwater system at the selected study sites. Results also indicated that PBOC demonstrated positive relationships with reductive dechlorination activity and the natural attenuation capacity of the sites. The findings of this study suggested that the level of PBOC in aquifer sediments may be a key factor in sustaining conditions favorable for microbial reductive dechlorination. In the third phase of this study, the distribution of PBOC was investigated at a chloroethene contaminated site. PBOC was measured in surficial aquifer sediment samples collected at varying depths in the vicinity of a chloroethene plume. Results demonstrated that levels of PBOC were consistently higher in aquifer sediments with minimal chloroethene exposure relative to samples collected in the PCE-contaminated source zone. Regression results demonstrated that a statistically significant inverse correlation existed between PBOC levels and chloroethene concentrations for selected temporary wells in the contaminated source zone at the study site. Consistent with these findings, results also indicated a similar trend of increased PBOC in aquifer sediments outside the chloroethene plume relative to aquifer sediments inside the plume. Results from this study further suggested that differences in extracted carbon levels at the site for surficial aquifer sediment samples in the PCE-contaminated source zone could impact the extent of reductive dechlorination within the hydrographic unit. / Ph. D.

No / Introduction Older people in care homes are at increased risk of medication errors and adverse drug events. The effect of formulation on administration errors is not known, that is whether the medicine is a tablet or capsule, liquid or device such as an inhaler. Also, the impact on administration errors of monitored dosage systems (MDS), commonly used in UK care homes to dispense tablets and capsules, is not known. This study investigated the influence of formulation and MDS on administration errors. Methods Administration errors were identified by pharmacists (using validated definitions) observing two drug rounds of residents randomly selected from a purposive sample of UK nursing and residential homes. Errors were classified and analysed by formulation and medicine delivery system. Results The odds of administration errors by formulation, when compared with tablets and capsules in MDS, were: liquids 4.31 (95% CI 2.02 to 9.21; p=0.0002); topicals/transdermals/injections 19.61 (95% CI 6.90 to 55.73; p<0.0001); inhalers 33.58 (95% CI 12.51 to 90.19; p<0.0001). The odds of administration errors for tablets and capsules not in MDS were double those that were dispensed in MDS (adjusted OR 2.14, 95% CI 1.02 to 4.51; p=0.04). Conclusions Inhalers and liquid medicines were associated with significantly increased odds of administration errors. Training of staff in safe administration of these formulations needs implementing. Although there was some evidence that MDS reduced the odds of an administration error, the use of MDS impacts on other aspects of medicines management. Because of this, and as the primary topic of our study was not MDS, a prospective trial specifically designed to evaluate the overall impact of MDS on medicine management in care homes is needed.