Growth room experiments were conducted to examine terrestrial and wetland-based phytoremediation approaches as alternatives to biosolids management. Results from both experiments show that biosolids do not need to be amended with soil to encourage plant growth and optimize biomass yields. In the terrestrial phytoremediation approach, two harvests per growth cycle produced greater switchgrass biomass yield than a single harvest but had no significant effect on cattail biomass yield during the first cycle. Repeated harvesting also significantly increased mean nutrient uptake in Cycle 1, reflecting the greater biomass yield from two harvests compared with a single harvest. In the wetland experiment, nutrient phytoextraction under two harvests was 4.25% of initial N content and 2.28% of initial P content compared with 2.9% and 1.58%, respectively, under a single harvest. Terrestrial phytoremediation could be beneficial to small communities that cannot afford the costly excavation, trucking, and eventual spreading of biosolids on agricultural land.

There is no abstract available for this thesis. / Department of Natural Resources and Environmental Management

Phytoremediation technologies offer an economical and practical alternative to traditional remediation technologies. This study attempted to quantify and compare the ability of DN34 and NM1 varieties of hybrid poplars to phytovolatilize the organic contaminant 1,4-dioxane. Research included laboratory experiments and those at an old industrial field site containing 1,4-dioxane and other organic contaminants. Under laboratory conditions it was found that when DN34 was exposed to 36 ppm of 1,4-dioxane in hydroponic solution it had a significantly higher transpiration rate than NM1. There were no toxic effects of the contaminant on the plants. Additionally, the DN34 variety was able to remove 48.7 ± 11.6 % (mean ± standard error) of the dioxane from aqueous solution compared to 41.7 ± 10.0 % removed by NM1. Water availability at the field site had a significant effect on growth rate whereas soil type and contaminant concentration did not appear to have any affect. It was apparent that DN34 had a significantly higher transpiration rates than NM1 in a dry, 2007 season, while the opposite was true during a wet, 2008 season. Interestingly, the DN34 variety had lower transpiration rates in the wet season than in the dry season. The presence of the co-contaminant ethylene glycol affected transpiration rate in the NM1 variety but not the DN34 variety. The NM1 variety had a decrease in transpiration rate of 42 and 30 % when growing in a mid-range concentration (≤ 1000 ppm) of ethylene glycol compared to a low concentration (≤ 100 ppm) of ethylene glycol in the wet and dry seasons, respectively. Unfortunately, detection of 1,4-dioxane removal by trees at the field site was difficult to achieve. / Thesis (Master, Biology) -- Queen's University, 2009-04-28 11:26:03.876

Lead (Pb) is the number one heavy metal pollutant in the environment. The high cost and environmental concerns of conventional remediation technologies has led to an emerging alternative technology for heavy metal remediation: phytoremediation. This study was set out to advance Pb phytoremediation by investigating plant-associated factors (e.g. polyphenol levels, Pb-tannin chelation, and superoxide dismutase activity) and chemical-based factors (e.g. concentration of Pb, and the type and dosage of chelating agents in treatments) that may affect Pb accumulation. Using a hydroponic system, sand-grown Symphytum officinale L. plants were exposed to nutrient solutions with or without lead nitrate (Pb(NO₃)₂) and ethylenediamine tetraacetic acid (EDTA). Using flame atomic absorption spectroscopy (to measure Pb content) and bovine serum albumin-protein precipitation (to measure polyphenol and tannin levels), a significant in vivo correlation between tannin level and Pb accumulation level was observed in roots of plants exposed to all Pb treatments. Higher tannin containing-lateral roots accumulated significantly more Pb than lowertannin main roots. Transmission electron micrographs of unchelated Pb-treated plants supported these findings, whilst dialysis-based in vitro Pb-chelation studies with crude S. officinale root polyphenol extracts did not. The dialysis method was likely to be subject to fructan interference. A new, more accurate and simple method based on tannin immobilisation was consequently developed. Results using this method supported the hydroponic trends. This new method was also verified with purified tannic acid (from Sigma). Together, these findings demonstrate that S. officinale root tannins have the ability to chelate Pb. This may be a mechanism to cope with Pb stress (adaptive tolerance). Despite the typical signs of Pb stress at root level (e.g. root growth inhibition, and degraded cytoplasms), shoots showed no signs of stress under any Pb treatments. Most importantly, since this chelation-based tolerance mechanism also influences the accumulation levels, the phytochemical composition of plants should also be considered when screening plants for phytoremediation. The level of Pb accumulated in the shoots depended on the concentration of Pb(NO₃)₂ and presence of chelating agents (EDTA or N-[2 acetamido] iminodiacetic acid (ADA)) in the nutrient solution. The highest level of Pb in shoots was between 0.05-0.06% (d.w. on average) using EDTA or ADA, well short of the 1% (d.w.) shoot accumulation target for Pb phytoextraction. The highest level of Pb in the roots (and of all measurements) was with unchelated 500 µM Pb(NO₃)₂; on average 2% (d.w.) accumulated in root. Overall, since S. officinale accumulated Pb predominately in the roots, it is most suited for rhizofiltration and phytostabilisation. Whilst chelating agents enhanced Pb accumulation in shoots, root levels were unexpectedly reduced compared to unchelated Pb treatments. The level of Pb translocated did not completely account for this loss. Minor factors relating to EDTA desorption of roots, EDTA specificity, and charge repulsion of the PbEDTA complex may account for some of the loss, but the main cause remains unclear. In vitro S. officinale cultures were developed and somaclonal variation (involving Pb pre-treatment of petioles) was used as a tool to further investigate, and attempt to improve its Pb phytoremediation potential. The shoots and roots of plants produced from petioles pre-treated with Pb(NO₃)₂ appeared more stressed than those without Pb pre-treatment. After re-treatment with Pb (Pb(NO₃)₂ or PbADA), plants developed from most Pb pre-treated petioles appeared to have reduced Pb accumulation and polyphenol levels, and increased superoxide dismutase activity in roots (although no statistically significant trends were found). Overall, plants produced from Pb pre-treated petioles in this study may have less phytoremediation potential.

Lead (Pb) is the number one heavy metal pollutant in the environment. The high cost and environmental concerns of conventional remediation technologies has led to an emerging alternative technology for heavy metal remediation: phytoremediation. This study was set out to advance Pb phytoremediation by investigating plant-associated factors (e.g. polyphenol levels, Pb-tannin chelation, and superoxide dismutase activity) and chemical-based factors (e.g. concentration of Pb, and the type and dosage of chelating agents in treatments) that may affect Pb accumulation. Using a hydroponic system, sand-grown Symphytum officinale L. plants were exposed to nutrient solutions with or without lead nitrate (Pb(NO₃)₂) and ethylenediamine tetraacetic acid (EDTA). Using flame atomic absorption spectroscopy (to measure Pb content) and bovine serum albumin-protein precipitation (to measure polyphenol and tannin levels), a significant in vivo correlation between tannin level and Pb accumulation level was observed in roots of plants exposed to all Pb treatments. Higher tannin containing-lateral roots accumulated significantly more Pb than lowertannin main roots. Transmission electron micrographs of unchelated Pb-treated plants supported these findings, whilst dialysis-based in vitro Pb-chelation studies with crude S. officinale root polyphenol extracts did not. The dialysis method was likely to be subject to fructan interference. A new, more accurate and simple method based on tannin immobilisation was consequently developed. Results using this method supported the hydroponic trends. This new method was also verified with purified tannic acid (from Sigma). Together, these findings demonstrate that S. officinale root tannins have the ability to chelate Pb. This may be a mechanism to cope with Pb stress (adaptive tolerance). Despite the typical signs of Pb stress at root level (e.g. root growth inhibition, and degraded cytoplasms), shoots showed no signs of stress under any Pb treatments. Most importantly, since this chelation-based tolerance mechanism also influences the accumulation levels, the phytochemical composition of plants should also be considered when screening plants for phytoremediation. The level of Pb accumulated in the shoots depended on the concentration of Pb(NO₃)₂ and presence of chelating agents (EDTA or N-[2 acetamido] iminodiacetic acid (ADA)) in the nutrient solution. The highest level of Pb in shoots was between 0.05-0.06% (d.w. on average) using EDTA or ADA, well short of the 1% (d.w.) shoot accumulation target for Pb phytoextraction. The highest level of Pb in the roots (and of all measurements) was with unchelated 500 µM Pb(NO₃)₂; on average 2% (d.w.) accumulated in root. Overall, since S. officinale accumulated Pb predominately in the roots, it is most suited for rhizofiltration and phytostabilisation. Whilst chelating agents enhanced Pb accumulation in shoots, root levels were unexpectedly reduced compared to unchelated Pb treatments. The level of Pb translocated did not completely account for this loss. Minor factors relating to EDTA desorption of roots, EDTA specificity, and charge repulsion of the PbEDTA complex may account for some of the loss, but the main cause remains unclear. In vitro S. officinale cultures were developed and somaclonal variation (involving Pb pre-treatment of petioles) was used as a tool to further investigate, and attempt to improve its Pb phytoremediation potential. The shoots and roots of plants produced from petioles pre-treated with Pb(NO₃)₂ appeared more stressed than those without Pb pre-treatment. After re-treatment with Pb (Pb(NO₃)₂ or PbADA), plants developed from most Pb pre-treated petioles appeared to have reduced Pb accumulation and polyphenol levels, and increased superoxide dismutase activity in roots (although no statistically significant trends were found). Overall, plants produced from Pb pre-treated petioles in this study may have less phytoremediation potential.

Thesis (M.E.S.)--The Evergreen State College, 2007. / Title from title screen (viewed 1/24/2008). "MES thesis." Includes bibliographical references (leaves 150-156).

Thesis (M.S.)--Youngstown State University, 2008. / Includes bibliographical references (leaves 38-41). Also available via the World Wide Web in PDF format.

Thesis (M.S.), Natural Resources, University of Wisconsin--Stevens Point, 2004. / Includes bibliographical references (leaves 43-47).

Thesis (M.S.)--West Virginia University, 2000. / Title from document title page. Document formatted into pages; contains vii, 38 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references (p. 34-36).

Dissertation (Ph.D.)--University of Toledo, 2010. / Typescript. "Submitted to the Graduate Faculty as partial fulfillment of the requirements for the Doctor of Philosophy Degree in Biology (Ecology track)." "A dissertation entitled"--at head of title. Title from title page of PDF document. Bibliography: p. 8-10, p. 21-25, p. 42-45, p. 63-66, p. 86-91.