The persistance of industrially derived polycyclic aromatic hydrocarbons in the subsurface may be significantly affected by the metabolism of soil bacteria. This study was conducted to determine the ability of indigenous soil bacteria to decrease the concentration of four polycyclic aromatic hydrocarbons (naphthalene, fluorene, anthracene, and pyrene) and to utilize the compounds as a substrate for growth. Soil cores from petroleum contaminated and non-contaminated sites contained 10⁵ - 10⁷ viable microorganisms per gram dry weight of soil. Gram negative rod-shaped bacteria predominated. Decreases in the concentration of the four polycyclic aromatic hydrocarbons were observed during incubation with bacterial isolates in aqueous suspension by the use of high performance liquid chromatography. Corresponding increases in bacterial numbers indicated utilization of the compounds as a carbon source. Soil samples from the contaminated sites contained greater numbers of bacteria utilizing anthracene and pyrene than soil samples from non-contaminated sites. Degradation rates of the four polycyclic aromatic hydrocarbons were related to the compound, its concentration, and the bacterium. Biodegradation of pyrene was positively correlated with the presence of oxygen. Pyrene was biodegraded by an Acinetobacter sp. under aerobic conditions but not under anaerobic or microaerophilic conditions. Studies with radiolabeled ¹⁴C-anthracene demonstrated utilization of the labeled carbon as a source of carbon by viable bacterial cells in aqueous suspension. Incorporation of ¹⁴C into cellular biomass however was not observed during incubation of ¹⁴C-anthracene in soil.

Helium tracer experiments were conducted to characterize conservative tracer behavior in a wedge-shaped lysimeter containing alternating layers of unsaturated silty sand, and clay loam. Experiments were conducted with trichloroethylene and 1,1,1-trichloroethane to determine if air stripping in unsaturated soil could be characterized by mass transfer from the sorbed to the liquid to the vapor phase. Batch experiments were conducted to measure liquid--vapor mass transfer. Solid-liquid-vapor mass transfer was characterized by measuring the vapor phase re-equilibration after the air stripping experiment. The Discrete State Compartment model was used to simulate a conservative gas tracer. The results were compared to the helium tracer. Liquid-vapor, and solid-liquid-vapor mass transfer were modeled by fitting simulated data to experimental data. The conservative tracer, and mass transfer models were combined to simulate air stripping in unsaturated soil.

In order to gain a better understanding of the mechanism of As(V) tolerance in rice, a number of hydroponic tolerance tests have been done on the interaction of As(V) with phosphate (PO₄^3-), reduced glutathione (GSH) and O₂ supply.  The PO₄^3—As(V) interaction test revealed that increasing PO₄^3- concentration reduces the toxicity of As(V).  Low PO₄^3- (0.05 mM) showed no protection against As(V) induced root inhibition, but higher PO₄^3- (0.5 and 5 mM) showed marked protection, suggesting PO₄^3- derived tolerance is not due to reduced PO₄^3- transport that has been postulated in other grass species.  The glutathione (GSH)-As(V) interaction test revealed a strong effect of GSH, increasing tolerance in rice.  The O₂ supply test also revealed a significant effect with enhanced tolerance in rice.  Therefore it can be suggested that PO₄^3-, GSH and air bubbling supply all reduces As(V) toxicity in rice by increasing tolerance.  The protection against As(V) provided by GSH and PO₄^3- were not the same for two rice varieties, Azucena (As sensitive) and Bala (As tolerant).  However these tolerance tests cannot explain why Azucena and Bala differ in susceptibility to As(V).  Three green house pot experiments revealed that As(V) treatment reduces growth in dose dependent way.  Total As concentration in the shoots and grain increases with the increasing concentration of the As(V) treatments.  Surprisingly, application of PO₄^3- does not alter As(V) toxicity.  Anaerobic (lowland) soil shows higher shoot As concentration but uptake is lower.  Rice genotypes show significant variation in their plant growth, total shoot As concentration and total As uptake which reveal that tolerant genotypes contain higher shoot As. Results of the hydroponics and pot experiments suggested that tolerance of rice is not derived from competition with As(V) at the PO₄^3- transporters, but rather reflects another, as yet unknown, mechanism.

A dissertation submitted to the Faculty of Science, University of the Witwatersrand, in ful llment of the requirements for the degree of Master of Science. March 27, 2013 / The transport of chemicals through soils to the groundwater or precipitation at the soils surfaces leads to degradation of the resources such as soil fertility, drinking water and so on. Serious consequences may be su ered in the long run. In this dissertation, we consider macroscopic deterministic models de- scribing contaminant transport in saturated soils under uniform radial water ow backgrounds. The arising convection-dispersion equation given in terms of the stream functions is analyzed using classical Lie point symmetries. A number of exotic Lie point symmetries are admitted. Group invariant solu- tions are classi ed according to the elements of the one-dimensional optimal systems. We analyze the group invariant solutions which satisfy some physical boundary conditions. The governing equation describing movements of contaminants under ra- dial water ow background may be given in conserved form. As such, the conserved form of the governing equation may be written as a system of rst order partial di erential equation referred to as an auxiliary system, by an in- troduction of the nonlocal variable. The resulting system of equations admits a number of (local) point symmetries which induce the nonlocal symmetries for the original governing equation. We construct classes of solutions using the admitted genuine nonlocal symmetries, which include the invariant solutions obtained via corresponding point symmetries of the governing equation.

Thesis (MTech (Environmental Health)--Cape Peninsula University of Technology, 2007 / The widespread use of lead (Pb) and especially Pb from vehicular emissions arising from lead additives in petrol has resulted in high levels of this metal found in various soil samples taken along the road verges of Cape Town CBD. The accumulation of lead was investigated in roadside surface soil by collecting soil samples at various sites along the three major highways (N7, N2, N1), approximately three metres from the road verges and at a depth of approximately 5 cm for a period of 12 months. After digestion with 55"70 nitric acid the Pb concentrations were determined by using an Inductively Coupled Plasma Atomic Emission Spectrophotometer (ICP-AES). Results have shown the Pb concentrations in the soil at busy intersections to be higher than at other areas along the roadsides. Lead concentrations found in the roadside soils of the N1 ranged between 200 and 2000 mg/kg and these were of the highest concentrations found compared to the other two highways and were even higher than found in other studies. The roadside soils on the N1 highway, with the most traffic, according to car count data obtained, seemed more contaminated than the other two highways. It was also investigated whether earthworms (Eisenia fetida) accumulated Pb after being exposed to the contaminated soil from the sampling sites. The earthworms in the highly contaminated soil accumulated on average much higher concentrations of Pb than the earthworms in the lower Pb contaminated soil. A potential biomarker (cell membrane integrity) was applied to determine whether the earthworms experienced toxic stress as a result of the exposure to lead contaminated soil. Behavioural and morphological changes in the earthworms were also observed. The Trypan blue exclusion assay was used to measure the effect of lead exposure on the membrane stability of the coelomocytes in the coelomic fluid of earthworms. In the highest exposure groups per highway, a significant decrease in percentage viable cells were seen (N7, 36 ± 0.07%; N2 48 ± 0.09%; N1, 34 ± 0.08%). The fact that clear statistically significant responses were seen after the five week exposure period in the highest, as well as lowest exposure groups indicate that these responses could serve as an early warning system of lead exposure. The percentage cell viability (biomarker) used in this study have been useful in identifying toxic stress in earthworms caused by lead in roadside soils. The additional information obtained by using biomarkers could not be obtained by chemical analysis of soil and earthworms alone.

A poluição do solo por uso de derivados de petróleo como o grupo de hidrocarbonetos denominado de BTEX (benzeno, tolueno, etil-benzeno e xilenos), apresenta grande risco às comunidades residentes próximas a esses locais. Esses compostos são tóxicos, comprovadamente cancerígenos e podem levar uma pessoa a morte, mesmo em concentrações extremamente baixas. O cidadão, muitas vezes não tem noção do que sejam estes contaminantes e o grande perigo que representam. Milhares de residências têm sido construídas sobre resíduos perigosos que continuam ativos, emitindo gases e/ou contaminando o lençol freático. Em particular, na região de Cubatão, o problema se agrava com o uso indevido de águas de rios e riachos, que por um processo de percolação, acabam sendo contaminados pelos poluentes presentes no solo, podendo ocorrer de o ponto de coleta de água ser próximo a um sítio contaminado. Este estudo relata o isolamento e caracterização de 4 cepas de bactérias isoladas de um solo contaminado com BTEX em Cubatão-SP, através da técnica de enriquecimento seletivo de culturas. A idéia é que estas cepas possam ser utilizadas em futuros processos de biorremediação (tratamento) destes solos. Além disso, o trabalho conta com o auxílio de programas sócio-ambientais existentes no Centro de Capacitação e Pesquisa em Meio Ambiente (CEPEMA-POLI-USP) os quais tem como um dos objetivos conscientizar a população carente cubatense, que faz uso indevido da água contaminada, aos perigos da exposição ao BTEX. / Contaminated soils by hydrocarbons known as BTEX (benzene, toluene, ethylbenzene and xylene), represent a risk to communities who live close to these places. These compounds are toxic, carcinogenic and can cause death to people, even in extremely small concentrations. Citizens often have no idea who and how hazardous are these contaminants. Millions of homes have been built on dangerous actives wastes, emitting gases and contaminating the groundwater. In particular, the problem is worst in Cubatão due inappropriate use of water from rivers and streams, which by a percolation process, contaminate soil. Most of times the water collected points are near from the contaminated site. This study reports the successful isolation and characterization of 4 bacteria strains isolated from an industrial soil in Cubatão-Brazil, using a culture enrichment technique. The idea is use these microorganisms in future soils bioremediation processes (treatment). This work have as partners, social and environmental programs from the Center for Training and Environmental Research (CEPEMA-POLI-USP), which has as goal educate poor people against dangers of BTEX.

Os manguezais estão sob constante risco de degradação devido a atividades industriais e portuárias nos estuários. Dentre estas atividades, a indústria petroquímica é uma importante fonte de poluição para estas áreas. Os efeitos dos hidrocarbonetos do petróleo sobre a comunidade de bactérias em solo de mangue são pouco conhecidos. O objetivo deste trabalho foi estudar as variações nas atividades e diversidade metabólica e genética da comunidade microbiana em solo de mangue contaminado com petróleo. A área de estudo está localizada no Canal de Bertioga (Santos, SP), e sofreu um derramamento de petróleo em 1983. Nesta área, foram coletadas amostras de 3 pontos, em triplicata, em uma transeção de 300m entre o Rio Iriri e o contato mangue-encosta. As amostras foram denominadas: P1, próximo às margens do rio; P2, ponto intermediário entre P1 e P2; P3, próximo ao local do derramamento, no contato mangue-encosta. A análise química das amostras mostrou que a poluição remanescente era maior em P3, diminuindo na direção de P1, provavelmente devido à maior influência das correntes de fluxo e refluxo de maré. De cada ponto foram coletadas subamostras, representando as camadas 0-5, 5-10, 10-15, 15-20, 20-30, 30-40, 40-50, 50-60, 60-70, 70-80, 80-90 e 90-100 cm, com exceção do P3, onde as amostras foram coletadas até 80 cm. Foram realizadas determinações de: pH, Umidade do Solo, Número Mais Provável (NMP) de Bactérias Heterotróficas Aeróbias, C-biomassa, Respiração Basal (RB), Respiração Induzida pelo Substrato (RIS), Quociente Metabólico (qCO2), Diversidade Metabólica e Diversidade Genética. O NMP de bactérias heterotróficas aeróbias foi em média 3,5 vezes maior no P3 do que no P1 e P2. A biomassa microbiana não variou com o ponto de amostragem, mas foi afetada significativamente pelo fator PROFUNDIDADE. Os maiores valores de C-biomassa foram observados na camada de 0 a 5cm. A RB foi afetada tanto pelo fator PONTO quanto pelo fator PROFUNDIDADE. No P3 a RB foi em média 39% maior do que no P1 e P2. Entre as profundidades, as amostras de 50 a 100cm apresentaram maior RB. A RIS foi afetada pela interação dos fatores PONTO e PROFUNDIDADE, sendo maior na camada de 0 a 5cm do P3. O qCO2 foi em média 45% menor no P2 do que no P1 e P3. A diversidade metabólica, avaliada pela capacidade de utilização de substratos de carbono não diferiu entre os pontos, mas apresentou decréscimo gradativo em função do aumento da profundidade. A separação de amplicons de rDNA 16S de Bacteria revelou uma diminuição da Riqueza de Espécies (SE) no P3, possivelmente devido à presença do petróleo. Essas alterações foram menores para Archaea. A análise de agrupamento hierárquico mostrou que as comunidades de Bacteria foram mais similares entre os pontos de amostragem do que entre as profundidades. Já, as comunidades de Archaea foram mais similares entre as profundidades do que entre os pontos de amostragem. De uma maneira geral, os resultados sugerem que, após 20 anos da contaminação com petróleo, as comunidades microbianas, principalmente de Bacteria, na área em estudo ainda não restabeleceram seu equilíbrio. / Mangroves are at constant risk of degradation due to industrial and harbor activities in the estuaries. Among potentially harmful activities, the petrochemical industries are important contamination sources for mangroves. Information on the effects of oil hydrocarbons on bacterial communities in mangrove soil is lacking. The objective of this work was to determine variations in the activities and metabolic and genetic diversities of microbial communities in an oil contaminated mangrove soil. The area studied is located in the Bertioga Channel (Santos, SP), and was contaminated by an oil spill in 1983. Samples were collected from three spots in a 300 m transect between the Iriri River and the mangrove-slope contact, and named: P1, spot in the vicinity of the riverbank; P2, intermediary spot; P3, spot in the vicinity of the oil spill (mangrove-slope contact). Chemical analyses of samples from these spots showed that the remaining oil concentration was higher at P3 and decreased towards P1, probably due the influence of flooding and tide reflux. From each spot, triplicate subsamples representing layers: 0-5, 5-10, 10-15, 15-20, 20-30, 30-40, 40-50, 50-60, 60-70, 70-80, 80-90 and 90-100 cm (except in P3, where sampling at depths higher than 80 cm was not possible) were collected. Soil samples were subjected to the following analyses: pH, Soil Humidity, Most Probable Number of Heterotrophic Bacteria (MPN), C-biomass, Basal Respiration (BR), Substrate Induced Respiration (SIR), Metabolic Quotient (qCO2), Metabolic Diversity and Genetic Diversity. The MPN of aerobic heterotrophic bacteria was 3.5 times higher in P3 than in P1 and P2. The microbial biomass did not show significant differences between sampled spots. However, significant differences were observed for sampling depths. The highest values of C-biomass were observed in 0 to 5 cm layers. The BR was significantly affected by factors SAMPLING SPOT and SAMPLING DEPTH. In P3, the average BR was 39% higher than in P1 and P2. Among sampling depths, the highest values for BR were observed at 50 to 100 cm. The SIR was significantly affected by the interaction between factors SAMPLING SPOT and SAMPLING DEPTH, and was highest in P3 at 0 to 5 cm. The average qCO2 was 45% lower in P2 than in P1 and P3. The metabolic diversity, based on the ability to use C-sources, did not differ among sampling spots, but showed a gradual decrease at greater depths. Analyses of Bacteria 16S rDNA amplicons by DGGE revealed lower species richness (SE) in P3, as compared to P1 and P2, which was probably associated with residual oil contamination. Archaea showed less variation in the samples. Hierarchical clustering showed that Bacteria community structures were more similar among sampling spots than sampling depths, whereas Archaea community structures were more similar among sampling depths than between sampling spots. In general, these results suggest that 20 years after an oil spill, Bacteria communities had been altered in a fashion that changed the community structure, but which did not affect their activity or function.

This project developed methodology for in vitro toxicity assessment of contaminated sites using the Promega?? MTS [3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxy-methoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium] assay performed on human cells (HepG2 and Skin fibroblasts). The project included the development of a method for extracting contaminants from soil based on leaching and centrifugation. A number of solvents and surfactants were assessed for their suitability as extracting agents. The Zwitterionic surfactant CHAPS ({3[(3-Cholamidopropyl) dimethylammonio] propanesulphonic acid}), which is an irritant in vivo, was found suitable for in vitro toxicity assessment applications. CHAPS was found to be the least toxic surfactant in vitro when tested on skin fibroblasts (NOEC: 1800??577 ppm, IC50: 4000??577 ppm) and HepG2 cells (NOEC: 833??289 ppm, IC50: 5300??287 ppm). The chosen surfactant was used in three different methods for extraction of Toluene and Xylene spiked in 2 g and 10g soil. The combination comprising of 0.1% (s/w) CHAPS and cosolvent 1% (w/w) Isopropanol, at their respective NOEC (No Observed Effective Concentration) toxicity values, showed good recovery of the nonpolar organic compounds in comparison to the recovery by 0.1% CHAPS and 0.5% CHAPS. The study found additive interactions to be the most common form of toxicity for 16 concentration combinations of Formaldehyde (polar), Toluene and Xylene (nonpolar) when compared to predicted toxicity (R2=0.943, P&lt0.0001). When assessing the in vitro toxicity of unknown (blind) contaminated soil samples, the Hazard Index (HI) predicted from the chemical analyses results showed a relatively good correlation (R2&gt0.7062, n=26) when compared to the experimental toxicity results on HepG2 cells. Furthermore, the comparison of Australian Health Investigation Levels (HIL) with in vitro toxicity testing gave similar correlation (R2&gt0.6882, n=26) on HepG2 cells. The overall project suggests the potential application of the zwitterionic surfactant (CHAPS) in sampling contaminants from soils in an in vitro toxicity assessment. This study demonstrates the application of in vitro toxicity assessment using human cells for the prediction of toxic risk as a sentinel to human toxicity from a contaminated site.

The aerobic transformation of TCE and cis-DCE by a tetrabutoxysilane-grown microorganism (Vancheeswaran et al., 1999) led to the investigation of novel substrates, including benzyl alcohol, for promoting cometabolism. The culture grew on carboxylic compounds and alcohols, but did not grow on formate, methanol, methane, propane, butane, ethylene, benzene, toluene, or p-xylene. Cis-DCE transformation was observed when the culture grew on butyrate, glucose, 1-propanol, 1-butanol, ethanol, benzyl alcohol, and phenol, and effectively transformed TCE, cis-DCE, and vinyl chloride when grown on phenol or benzyl alcohol. Several cycles of growth on benzyl alcohol led to increases in TCE transformation rates and transformation capacities. Products of benzyl alcohol degradation shifted from benzaldehyde to 2-hydroxy benzyl alcohol (2HBA) during the several cycles of growth. In resting cells studies, 2HBA production rates were highly correlated with TCE transformation rates. TCE transformation and 2HBA production rates doubled when the culture was grown on phenol and rates of TCE transformation were correlated with 2HBA production rates. Benzyl alcohol- and phenol-grown cells oxidized toluene to o-cresol, which indicated the similarity between benzyl alcohol ortho-monooxygenase, phenol hydroxylase, and toluene ortho-monooxygenase. 2-Butyne and 1-hexyne (but not acetylene) inhibited benzyl alcohol- and phenol-grown cells similarly, indicating the same ortho-monooxygenase was responsible for TCE cometabolism. Resting cell kinetic studies were performed with cells grown on phenol or benzyl alcohol. Benzyl alcohol degradation followed a Monod kinetics while phenol degradation followed a Haldane kinetics. The maximum transformation rates (k[subscript max]) of TCE, cis-DCE, and VC achieved by phenol-grown cells were about a factor of two higher than achieved with benzyl alcohol-grown cells, while the half-saturation constants (K[subscript s]) were in a similar range. Transformation capacities (Tc) for TCE, cis-DCE, and VC were about a factor of two to four higher with phenol-grown cells. The modeling of TCE, cis-DCE, and VC transformation using independently measured k[subscript max] and K[subscript s] values matched well with observed data from batch tests. Benzyl alcohol was shown to be an effective novel substrate for the aerobic cometabolism of TCE, cis-DCE, and vinyl chloride. Being a non-regulated compound, it might have applications for in-situ bioremediation. / Graduation date: 2004

Thesis (doctoral)--Swedish University of Agricultural Sciences, 2006. / Thesis documentation sheet inserted. Appendix reprints four manuscripts co-authored with others. Includes bibliographical references. Also issued electronically via World Wide Web in PDF format; online version lacks appendix.