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Polychlorinated biphenyls (PCBs) are persistent organic pollutants, which were banned several decades ago but still exist in the environment, posing a threat to human health. Previously, joint sealants containing PCBs were used in construction. In this study, the long-term PCB-contaminated soils were from a residential area in Västerås Municipality, where the PCBs have been leaching from buildings to the soil for several years. The objective of this thesis is to investigate the feasibility of using plants to remove PCBs from the contaminated soil at a greenhouse scale, and to use a site-specific guideline model for the risk assessment of this contaminated site. After a literature review, four plant species were selected for the greenhouse cultivation including alfalfa (Medicago sativa L.), white clover (Trifolium repens L.), horseradish (Armoracia rusticana L.) and tobacco (Nicotiana tobacum L.). The plants cultivated in the greenhouse were maintained for 92 days and then the concentrations of PCBs in the initial and remediated soils were analyzed by GC-MS. The results indicate that the selected plant species can enhance the removal of high chlorinated PCBs from soils. In the risk assessment, the contents of PCBs in soils were higher than the calculated site-specific guideline, which means it is urgent to implement measures for protecting residents’ health.

Plants are exposed to various environmental contaminants through irrigation with reclamation water and land application of municipal biosolids. Plants have been shown to take up contaminants from soil and groundwater, and to some extent, metabolize them in their tissues. These mechanisms have potential important implications for the environment and human health. First, as plants constitute the basis of the terrestrial food chain, accumulation of toxic chemicals or their metabolites inside plant tissues may lead to contamination of animals and humans. Second, the recognition of the capability of plants to take up and metabolize contaminants has led to the development of a plant-based remediation technology, referred to as phytoremediation. Phytoremediation is defined as the use of higher plants for the removal of environmental contaminants from soil and groundwater. Although phytoremediation is conceptually attractive as a green, environmental-friendly technology, the metabolism of xenobiotic compounds by plants is often slow and incomplete, possibly resulting in the accumulation of toxic pollutants and/or their metabolites inside plant tissues. Without further detoxification, phytoremediation may result in pollution transfer, potentially threatening the food chain, and eventually humans. Gaining further knowledge about the fate of environmental contaminants inside plant tissues is therefore of paramount importance for conducting environmental risk assessment and enhancing the efficiency of phytoremediation applications. It's an attractive concept today to cultivate plants on contaminated lands, in order to combine the benefits of phytoremediation with plant-based biofuel production. Unlike conventional plant bioenergy production, plant biomass grown on marginal contaminated soil will not compete with land for food production. However, the effect of contaminants on the plant biomass and bioenergy feedstock yield have received little attention. Molecular biology techniques, such as high-throughput gene expression analysis, constitute powerful tools to understand the molecular bases of the plant metabolism and response to environmental contaminants. The objective of this thesis is to understand the physiological and transcriptional responses of two model plants, thale cress (Arabidopsis thaliana) and soybean (Glycine max), exposed to various classes of contaminants, including silver nanoparticles (AgNPs), pharmaceuticals (zanamivir - ZAN and oseltamivir phosphate - OSP), explosives (2,4,6-trinitrotoluene - TNT), and polychlorinated biphenyls (PCBs). Detection of the contaminants inside plants tissues was performed using advance analytical methods, including inductively-coupled plasma - mass spectrometry (ICP-MS), gas-chromatography - mass spectrometry (GC-MS), and liquid-chromatography (LC-MS). The effects of contaminants on plants were assessed by recording various plant metrics, including biomass, root and shoot length, and soybean production. The transcriptional response of plants to exposure to selected contaminants (AgNPs, OSP, and ZAN) was investigated using whole-genome expression microarrays and reverse-transcription real-time (quantitative) PCR (RT-qPCR). In the first experimental phase of this research, the effects of AgNPs and soluble silver (Ag+) on A. thaliana plants were investigated. AgNPs are widely used nanomaterials, which have raised environmental concerns because of their toxicity to most living organisms, including plants. Exposure of hydroponic A. thaliana plants for 14 days to 20-nm AgNPs resulted in a slight increase of the biomass at low concentrations (1.0 and 2.5 mg / L) and a significant decrease of the biomass at higher concentrations (5.0 to 100 mg / L). Exposure to Ag+ for 14 days resulted in a significant reduction of the biomass after 14 days at concentration at and above 5.0 mg / L. Genome-wide expression microarrays revealed that exposure of A. thaliana to AgNPs and Ag+ at the concentration of 5 mg / L for 14 days resulted in differential expression of many genes involved in the plant response to stress and to biotic and abiotic stimuli. Although distinct gene expression patterns developed upon exposure to AgNPs and Ag+, a significant overlap of differentially expressed genes was observed between the two treatments, suggesting that AgNP-induced stress originated partly from silver toxicity and partly from nanoparticle-specific effects. In the second experimental phase of this research, the effects of the antiviral drugs, OSP and ZAN, on A. thaliana were investigated using an approach similar as the one described above. OSP and ZAN are pharmaceutical drugs that currently constitute the last line of defense against influenza infection. These drugs have been widely detected in wastewater effluents, especially during the influenza season, and they have the potential to contaminate agricultural plants through irrigation and land application of biosolids. Exposure of A. thaliana to OSP showed a significant decrease in the plants biomass at the concentrations of 20 and 100 mg / L, although no significant effect on the biomass was recorded upon exposure to ZAN (up to 100 mg / L), suggesting low acute toxicity of these compounds on plants. On the other hand, Arabidopsis exposure to OSP and ZAN at 20 mg / L resulted in significant transcriptional changes, including up- and down-regulation of many genes involved in the plant response to oxidative stresses and response to stimuli. Comparison with an Arabidopsis gene expression database (Genevestigator), revealed that many genes significantly up- and down-regulated by exposure to OSP and/or ZAN were similarly affected by exposure to biotic and abiotic stresses, toxic chemicals, and hormonal stimuli, suggesting that OSP and ZAN have negative chronic effects on plant health. The third experimental phase of this thesis focuses on the effects of two important persistent pollutants, TNT and PCBs, on the growth of soybean plants, with the objective of assessing the potential of using energy crops for the combined benefit of land remediation and biofuel (biodiesel) production. Explosives, such as TNT, are common toxic contaminants frequently observed at explosive manufacturing sites and military training ranges. PCBs are ubiquitous and toxic contaminants that are found in virtually every compartment of the environment. Short-term growth inhibition tests conducted with TNT and selected PCBs (e.g., 2,4'-dichlorobiphenyl - 2,4'-DCB) showed that these compounds exerted no or mild observable effects on plant growth even when applied at very high concentrations (i.e., 100 to 250 mg / kg soil, respectively). Analysis of TNT and 2,4'-DCB in exposed plant tissues showed average concentrations of 30 - 40 ng/g of TNT and 9,000 to 17,000 ng/g of 2,4'-DCB, which is consistent with biotransformation of TNT inside plant tissues. On the other hand, long-term exposure experiments show that exposure to TNT significantly affected soybean growth and production of bean in TNT-exposed plants (25 - 50 mg / kg soil). Exposure to TNT resulted in a significant decrease of the biomass of harvested beans after 120 days, which may have important consequences on the yield of biodiesel obtained from plants grown on contaminated land. Soybean were then exposed to 2,4'-DCB and its major transformation products, 4-OH-2,4'-DCB). Although high concentrations of the parent PCB (100 and 200 mg / kg) resulted in significant decrease of the biomass, high concentrations of the OH-metabolite resulted in increase of the plant biomass. Future research work will include the determination of the molecular bases of the effects - both positive and negative - of TNT, PCBs, and OH-PCBs on soybean plants and beans. / Civil Engineering

A numerical model is presented to describe solute transport in groundwater coupled to sorption by plant roots, translocation into plant stems, and finally evapotranspiration. The conceptual model takes into account both Root Concentration Factor, RCF, and Transpiration Stream Concentration Factor, TSCF for chemicals which are a function of Kow. A similar technique used to simulate the solute transport in groundwater to simulate sorption and plant uptake is used. The mathematical equation is solved using finite difference technique to solve for the concentration at any grid cell with respect to time. The new package is integrated into SEAM3D to create a new SEAM3D Plant Uptake Package, or PUP. The model is then verified by comparing results for root sorption in one side to the SEAM3D Reaction Package, and results for plant uptake to the SEAM3D Source Sink Mixing Package. The verification results showed an excellent match, which led to using the new package in a series of design application scenarios to evaluate phytoremediation effect. Hypothetical design scenarios included: 1) the effect of a phytoremediation system dimensions, 2) the effect of phytoremediation plant density or maximum ET rate, 3) the effect of out-flux of the phytoremediation with respect to the natural aquifer in-flux, and 4) the effect of using a phytoremediation system when the source of contamination is removed. For all the previous study cases, the results evaluate the effect on: 1) contaminant concentrations downstream the source (expressed in plume length at a concentration 1% of the source concentration), 2) solute mass removal from the aquifer, and 3) mass-flux changes at different cross-sections downstream the contaminant source. The results indicating the followings: 1) the width of the phytoremediation system, WET, has a limited effect on the solute mass-removal; 2) high tree density close to the contaminant source has a greater effect on solute mass removal relative to uniform density of trees planted over the entire plume; 3) the width of the ET area will have only a slight effect on the mass removal if the TSCF value is small; 4) as the value of TSCF gets lower, the efficiency of solute mass uptake is lower, and thus the solute concentration in groundwater is higher regardless of the quantity of water transpired; 5) dynamic steady-state plume dimensions (specially the plume length) are affected by the groundwater in-flux, which will control the dimensions and density of a phyto system; 6) splitting the phyto system into two halves does not have the same outcome of having one piece of area closer to the contamination site; 7) using a phyto system after the contamination source is removed led to increasing the solute concentration in the areas of the trees and decreases the concentration in the areas downstream the trees. The alternative model gives more options for simulation of solute mass uptake by plants by making use of field and lab data between the solute dissolved concentration in groundwater C, and solute mass in tree's core M to select a modeling category of three: Linear (ISO-1), Freundlich (ISO-2), and Langmuir (ISO-3). Each modeling option depends on the designer selection according to the fitted equation parameters between, C and, M. In terms of conservative results, ISO-1, and ISO-2 give less mass removal results than ISO-3 in case of sources with low concentrations. ISO-2, and ISO-3 give less mass removal results than ISO-1 in case of sources with high concentrations. / Ph. D.

Ten strategically placed push-pull wells were installed to determine in-situ degradation rates at a creosote contaminated site and to assess the contribution of hybrid poplar trees to polynuclear aromatic hydrocarbon (PAH) remediation. Well positioning enabled comparison between contaminated and non-contaminated locations, as well as comparisons between locations with and without trees. Comparison of areas with and without trees enabled an improved understanding of the role that the phytoremediation system has on the overall degradation of PAHs at the site. Bromide, a conservative, non-reactive tracer, was injected in solution along with dissolved oxygen. Twelve push-pull tests (PPTs) were performed, of which three did not include naphthalene in the injection solution, so that the developed method could be evaluated, tested, and yield an initial set of rates to make seasonal and spatial varying in-situ comparisons. Method comparison used for rate analysis found the highest confidence in the method of Snodgrass and Kitanidis (1998) for zero order rates and the method of Haggerty et al. (1998) for first order rates. The largest zero and first order rates, 2.43 mgnaphthalene/L-hr and 1.25 1/hr, respectively, occurred at treed regions in June. Zero and first order winter rates at treed regions were greater by a factor of at least 2.5 when compared to non-treed regions. Degradation rates at treed regions were found to steadily increase by over four times from winter to summer. Results validate that decay variations attributed to phytoremediation can be detected with the push-pull method. PPTs performed at the Oneida site verified observed trends determined from six years of monitoring data, microbial characterization, and microcosm studies. / Master of Science

Direct transpiration rates and plant uptake of naphthalene by a hybrid poplar phytoremediation system located in Oneida, Tennessee were determined using hydrologic and groundwater concentration data. Water table recession analysis techniques were employed to determine direct transpiration rates from the saturated zone of the shallow, unconfined aquifer underlying the site. Direct transpiration rates varied over the growing season (late March to mid-October), with a maximum and mean daily direct transpiration of 0.0100 and 0.0048 feet/day, respectively. During 2004, the maximum direct transpiration rate was observed in May, and rates declined starting in June due to an associated decline in the water table. A technique was developed to estimate the volumetric transpiration rate of each tree based on the breast-height diameters and seasonally variable direct transpiration rates. During peak transpiration, the larger trees at the study site were estimated to directly transpire 4 to 13 gallons per day per tree. Plant uptake rates of naphthalene were estimated by superimposing spatial data (volumetric transpiration rates and naphthalene concentration in groundwater). The mass loss rate of naphthalene from the aquifer as a result of plant uptake during July 2004 was 335 mg/day which only represents 0.117% of the aqueous mass plume. Monthly groundwater profiles showed a decrease of the saturated thickness beneath the system of hybrid poplars between the dormant and active season. This study suggests direct transpiration rates and plant uptake of naphthalene are dependent on variables including climatic parameters, magnitude of the saturated thickness, and the concentration of naphthalene in groundwater. / Master of Science

The 2014 Agricultural Act (Economic Research Division) (aka: The Farm Bill) was an important limelight shone on the issue of access to healthy foods, food education and the correlation between an increasingly unhealthy population and proximity to fresh, healthy food. Further legislation such as the Urban Agricultural Production Act of 2017 has been introduced to leverage the Farm Bill's financial incentives to promote urban agricultural programs and transform vacant land into agricultural use. Specifically, this has become increasingly common in many lower income and disadvantaged communities affected by a lack of access to fresh food stores. Additionally, in response many public schools have pro-actively sought funds to transform their schoolyards into gardens and teaching classrooms (Gamson) in order to provide food literacy and education however, this practice remains the exception. Many children still face a lack of healthy food options or the availability of any fresh food outside of their school environment. What if the standard education facility could be used as a tool to confront not only the architecture of the learning space, but a school-as-ecosystem, representing a neighborhood catalyst to teach through action – addressing comprehensive global issues brought on by food desert environments and a child's perspective about their own health? This thesis explores the possibility of casting the urban ecological net wide- envisioning a timescale for transforming public spaces and school grounds using green infrastructure practices, biological remediation, planning for changes in transportation technology and the expectations of a public education and child's perception about their environment. Emphasizing a broad focus on all of the potential sites for food production in the city (including the school, schoolyard and what they represent to the community), surfaces a multi-functioning methodology encompassing community identity, amenity, ecology, infrastructure and beauty envisions what could become of urban areas in the future. The primary goal is to educate future generations in the value of the food network and to give them the kind of direct hands-on experience that educators emphasize while concurrently nourishing urban communities through development of a project carried out in common, one that has health benefits for the population, that engenders a sense of long-term pride, and that empowers people to make change in their environment, even in modest or temporary ways. The idea that school design can encourage and facilitate, hinder and inhibit behaviors at school, and the architectural symbolism of schools can have a profoundly wider impact on children and their behaviors in and outside of school (Tucker). There is a significant psychological difference in learning about the environment, for the environment and in the environment (Malone). Creating public space focused on individual learning and the physical and mental health of the individual aims to balance the scales of social economic injustices. It is going to take every effort from the hyper-localized to city-wide and even regional scales to make significant urban changes to create a taxonomy of spaces to support the growth of our cities while simultaneously educating young minds on the value of understanding our ecological relationship to the city and surrounding environment. / Master of Science / The 2014 Agricultural Act (Economic Research Division) (aka: The Farm Bill) was an important limelight shone on the issue of access to healthy foods, food education and the correlation between an increasingly unhealthy population and proximity to fresh, healthy food. Further legislation such as the Urban Agricultural Production Act of 2017 has been introduced to leverage the Farm Bill’s financial incentives to promote urban agricultural programs and transform vacant land into agricultural use. Specifically, this has become increasingly common in many lower income and disadvantaged communities affected by a lack of access to fresh food stores. Additionally, in response many public schools have pro-actively sought funds to transform their schoolyards into gardens and teaching classrooms (Gamson) in order to provide food literacy and education however, this practice remains the exception. Many children still face a lack of healthy food options or the availability of any fresh food outside of their school environment. What if the standard education facility could be used as a tool to confront not only the architecture of the learning space, but a school-as-ecosystem, representing a neighborhood catalyst to teach through action – addressing comprehensive global issues brought on by food desert environments and a child’s perspective about their own health? This thesis explores the possibility of casting the urban ecological net wide- envisioning a timescale for transforming public spaces and school grounds using green infrastructure practices, biological remediation, planning for changes in transportation technology and the expectations of a public education and child’s perception about their environment. Emphasizing a broad focus on all of the potential sites for food production in the city (including the school, schoolyard and what they represent to the community), surfaces a multi-functioning methodology encompassing community identity, amenity, ecology, infrastructure and beauty envisions what could become of urban areas in the future. The primary goal is to educate future generations in the value of the food network and to give them the kind of direct hands-on experience that educators emphasize while concurrently nourishing urban communities through development of a project carried out in common, one that has health benefits for the population, that engenders a sense of long-term pride, and that empowers people to make change in their environment, even in modest or temporary ways. The idea that school design can encourage and facilitate, hinder and inhibit behaviors at school, and the architectural symbolism of schools can have a profoundly wider impact on children and their behaviors in and outside of school (Tucker). There is a significant psychological difference in learning about the environment, for the environment and in the environment (Malone). Creating public space focused on individual learning and the physical and mental health of the individual aims to balance the scales of social economic injustices. It is going to take every effort from the hyper-localized to city-wide and even regional scales to make significant urban changes to create a taxonomy of spaces to support the growth of our cities while simultaneously educating young minds on the value of understanding our ecological relationship to the city and surrounding environment.

In 1990, creosote contamination was discovered at the location of a railroad tie treatment facility active in the 1950s until 1973. In 1997, a phytoremediation field study was implemented with the planting of 1,026 hybrid poplar trees and 36 cells of vegetated and unvegetated grass and legume treatments. The hybrid poplar tree phytoremediation system was designed to control infiltration and groundwater flow and enhance subsurface remediation. The grass phytoremediation system was designed to control erosion and enhance surface soil remediation. The overall objectives of this study were to: (1) assess the extent of subsurface remediation, (2) determine the mechanisms of remediation attributable to the hybrid poplar tree phytoremediation system and microbial degradation, (3) assess the effects of the grass phytoremediation system on surface soil remediation, and (4) determine the mechanisms of surface soil remediation resulting from the grass phytoremediation system. / Master of Science

Studies were conducted to explore the interactions among rye grass, chlorophenols and microorganisms. The objectives were to examine some of the processes by which plants affect the fate of subsurface organic contaminants. The research was divided into three studies: interactions between live grasses and 2,4-dichlorophenol (DCP), 2,4,6-trichlorophenol (TCP), and pentachlorophenol (PCP); physico-chemical interactions between the three chlorophenols and root tissue; and effect of root exudates on biodegradation of TCP. To study the interactions between plants and organic contaminants, rye grass plants were grown in solutions containing DCP, TCP or PCP for one to three weeks. The grass removed substantial amounts of the chlorophenols throughout the incubation time. The majority of each chlorophenol removed from solution could not be recovered by non-destructive solvent extraction. The removal of the chlorophenols from solution and the unrecoverability of the removed compound followed different kinetics, indicating that the two are different processes. Both contaminant removal and unrecoverability were closely related to root surface area but not to transpiration. A qualitative model was developed to describe the uptake of organic contaminants by plants. The data demonstrate the importance of physico-chemical interactions between contaminants and roots and suggest that maximization of root surface area should be one consideration when selecting a plant species for phytoremediation. To study the physico-chemical interactions between plant roots and organic contaminants, the distribution of DCP, TCP and PCP within a three phase system was examined. The three phases were severed grass roots, water and an organic solvent, either hexane or ethyl acetate. The chlorophenol mass that partitioned into the solvent phase was inversely correlated with root mass and root surface area index. Partition coefficients calculated with respect to the organic liquid phase were inversely correlated with root mass and root surface area index. A similar partitioning experiment was conducted using PCP placed in a solution containing only the dissolved organic material released by roots. These resulting partition coefficients decreased with increasing organic carbon concentration. It appeared that the organic compounds released into solution by the roots affected the movement of the chlorophenol into the organic liquid phase. It is proposed that the presence of roots simultaneously promoted retention of the chlorphenols in the aqueous phase and provided a sorption site. The effect of grass root exudates and glucose on the lag time associated with 2,4,6-trichlorophenol (TCP) degradation by an unacclimated microbial inoculant and an acclimated microbial inoculant was investigated. The presence of an alternate organic carbon source reduced lag time for both the acclimated microbial inoculant and the inoculant that had not been previously exposed to chlorinated phenols. The lag time for acclimation of microbes to TCP mineralization was affected by the ratio of the alternate organic carbon source concentration to the biomass concentration. It is proposed that the presence of a readily available, alternate organic carbon source affected lag time through promotion of microbial population growth and provision of a preferred source of carbon and energy. The results indicate that rye grass may directly, through partitioning and uptake, and indirectly, through soil microbes, affect the fate of chlorophenols in the subsurface environment. / Ph. D.