Soil salinity affects an estimated one billion hectares worldwide. Excess salinity inhibits plant growth, limiting crop production. This is caused by osmotic stress in saline soil, nutrient imbalance and specific ion toxicity. There have been many methods of remediation investigated, including excavation, soil washing and phytoremediation. Phytoremediation involves the growth of plants on impacted soils to degrade or sequester contaminants. The remediation of salts relies on the uptake of ions into plant biomass where the salt is sequestered and the biomass can then be harvested. This method removes the salt from the site and leaves the top soil in place, which aids in revegetation after site remediation is completed. Plant-growth promoting rhizobacteria (PGPR) improves plant growth by lowering the levels of stress ethylene within the plant, thereby increasing the biomass available to sequester ions. The objectives of this research were to investigate the efficiency of phytoremediation of salt impacted soils in field remediation sites. Previously isolated strains of PGPR (UW3, Pseudomonas putida; UW4, Pseudomonas putida; and CMH3, Pseudomonas corrugata) were used in field trials involving the planting of oats (Avena sativa), annual ryegrass (Lolium multiflorum), tall wheatgrass (Agropyron elongatum) and tall fescue (Festuca arundinacea C.V. Inferno). The salt tolerance of various switchgrass (Panicum virgatum L.) cultivars (Cave-In-Rock, Southlow, Forestburg, and common) was compared to tall wheatgrass and Inferno tall fescue to investigate the potential of switchgrass for phytoremediation. Improvement of seed germination under salt stress by H2O2 pre-treatment was investigated both as an individual treatment and in combination with CMH3 treatment. The ion uptake into plant biomass was iii compared to the change in salinity, to determine how much of the decrease in site salinity is accounted for by uptake of salt by plants. H2O2 pretreatment resulted in a 50% increase in root and shoot emergence of tall wheatgrass under 75 mM NaCl stress compared to control treatments, which matched the germination improvement observed with PGPR treatment. The combination of H2O2 and CMH3 showed a similar improvement to root emergence under stress, but had no observable effect on shoot emergence when compared to the no-H2O2-no-PGPR control. Switchgrass cultivars showed a lower germination rate than tall wheatgrass at salt levels from 0 mM to 150 mM NaCl. The measured uptake of Na+, K+, Ca2+, Mg2+ and Cl- into plant biomass during a phytoremediation field trial was able to account for approximately 70% of the observed change in salinity in 2008. In 2009 the uptake of Na+ and Cl- into Kochia scoparia, a weed species that invaded the field site after a hard frost, was able to account for 36% of the observed change in salinity.

In this study we used the phytoremediation techniques to treatment diesel contaminated wetland soil. At first, we compared the four common wetland plants, Typha orientalis Presl, Cyperus malaccensis, Bolbos choenus planieulmis and Phragmites communis, on the treatment efficiency of the diesel contaminated wetland soils. From the results, we find out that the Typha orientalis Presl has highest growth rate and activity on rhizosphere among the four species. The Typha orientalis Presl was planted on artifical diesel contaminated wetland soil and incubated inside a greenhouse, while a control system without vegetation is compared. After 240 days, the result shows that soil planted with Typha orientalis Presl can enhance the microbial and dehydrogenase activity. And adding with nutrients can help plants to prevent the diesel stress. Finally, we utilized the PCR/DGGE methods to analyze soil microbial diversity. According to the DGGE profiles, presence of Typha orientalis Presl can augment microbial diversity . So far as degradation of TPH-d to be concerned, because of the period was too short, it doesn¡¦t have significant difference between treatments. However, presence of Typha orientalis Presl and addition of nutrients, the TPH-D degradation rate was measured to be approximately 80 % and concentration of TPH-D could degrade from 16000 mg kg-1 to 3500 mg kg-1 after 240 days.

In this study we attempt to use phytoremediation techniques to treat the contaminated soil of cadmium. The experiment is divided into two stages. In the first stage, we selected three different species of plants which could tolerate heavy-metals: vetiver (Vetiveria zizanioides), Pteris ensiformis cv. 'Victoriae' according to the past records, and Alternanthera philoxeroides (Mart.) Griseb, which were sampled from the metal contaminated site in Hunei, Kaohsiung county. These three species were planted in three pots with 10, 20 and 30 mg Cd kg-1 in soil respectively. After 9 weeks of the growth, the vetiver was found accumulating the highest Cd and grew better than the other two species. Therefore, we selected the species of vetiver in the second stage of experiment. First, the species of vetiver was planted in the pots with concentrations of 30 and 50 mg Cd kg-1 in soil respectively. Then the pots were put in the greenhouse for incubation. After the test was run for 210 days, we found that the species of vetiver was helpful in the increasing the number of species and amounts of each species of microbe ( total bacteria, fungi and actinomycete ), as well as dehydrogenase activity. Meanwhile, it was effective to decrease the bioavailability of cadmium. In addition, the infection rate of mycorrhizal fungi was increased , which showed that the species of vetiver could resist the cadmium stress in soils and stimulate the soil fertility. Finally, we use molecular biotechniques of PCR-DGGE to observe the microbial diversity in the contaminated soil. We found that the pots with 30 mg Cd kg-1 in soil had more number of bands than the pots with different Cd concentrations in soil, while the pots without vegetation was found more fruitful than vegetated pots. These experimental results indicated that the pots planted with the species of vetiver under this situation would help some special microorganisms to grow, and thus that the microbial diversity was reduced. The results also showed that the pots planted with vetiver with initial cadmium concentrations of 30 and 50 mg Cd kg-1 respectively, in soil exhibited the degradation rate of about 30 percent for both. It was not satisfied to this result in this study. However, the phytoextraction rates of cadmium were measured equal to 7.8 and 8.9 percent, respectively. According to these results, we suggested that the plant, which could hyperaccumulate heavy metals, might be used to increase the removable ability of cadmium in the future.

In this study, the phytoremediation techniques are used to treat the soil contaminated by pentachlorophenol(PCP).First, four plants species were selected,including Allium tuberosum, Vigna radiata (L.) Wilczek, Pennisetum alopecuroides, and Medicago sativa to compare their treatment efficiencies for PCP in soil.The experimental results showed that the species of Allium tuberosum presented the highest degradation rate 76% after 35-day test run with the initial concentration of 20mg/kg in soil. In the second stage,the species of Allium tuberosum was thus selected to run the tests of feasibility of using phytoremediayion to treat the soils contaminated byPCP.During the e xperiment,the pot tests inside a greenhouse were run for 330 days.The result indicated that the species of Allium tuberosum contributed to the increase of microorganism and dehydrogenase activity in the soil. Bisides,we also found that adding with nutrients could help Allium tuberosum to depress the PCP stress.The test with vegetation of Allium tuberosum and addition of nutrients showed that the PCP degradation rate was measured equal to 98.4% with the concentration of PCP degraded from 42mgkg-1 to 0.68mgkg-1 after 330days. Finally, molecule biotechnology of PCR-DGGE was applied to the test of observing the microbiota in the soils.According to the test results,we found that the diversity of microorganisms could be raised through planting the species of Allium tuberosum. The microbiota in the soils with PCP pollutant have more varieties than the microbiota in soils without vegetation, which was infered that the addition of PCP might stimulate the vitality of microbes in the soils. Moreover, comparing the microbiota on rhizosphere of the plant species and in the bulk soils, it was found that the actitivies of root exudates might be able to increase the varieties of rhizospheric microorganisms.

The purpose of this study was to treat soils contaminated by pyrene through phytoremediation. The plant species selected were Phragmites communis Trin., Typha orientalis Presl, Vetiveria zizanioides, Rohdea japonica (Thunb.) Roth et Kunth, Cyperus malaccensis. Lam. subsp. monophyllus (Vahl) T. Koyama, Bolboschoenus planiculmis (F. Schmidt) T. Koyama and Bidens pilosa respectively. The degradation efficiencies of pyrene in soils and concentration of pyrene in the plant tissues were evaluated in this study. In addition, the change of microbial biota in soils was investigated in the tests of this study. The experimental results indicated that after twenty-two weeks, soils planted with V. zizanioides, R. japonica and T. orientalis have better pyrene degradation efficiencies. Especially, after fourteen weeks the pyrene degradation efficiencies were 86%, 84% and 77% respectively, which showed that the efficiencies 10% to 20% higher than those unplanted control experiments, which was 66%. In addition, the pyrene degradation efficiencies in summer were found to be higher than those in winter. The degradation efficiencies of pyrene in sterilized soil with and without T. orientalis were found equal to 59% and 55%, respectively. These values were found lower than those in the experiment without sterilization, in which the pyrene degradation efficiencies with and without T. orientalis were 77% and 66%, respectively, after the fourteen weeks experiment. Hence the rhizospheric microorganisms had a significant effect on the degradation of pyrene in soils. The pyrene degradation efficiencies were improved with application of fertilizer (HYPONeX No.2, HYPONeX Co., USA). After fourteen weeks, it was found that the experiment with fertilizer and with or without T. orientalis planted were 7% higher, which were 84% and 73% respectively, compared to 77% and 66% with no application of fertilizer. Proper surfactants have positive effect on phytoremediation. In this study, we found that addition of the surfactant Triton X-100 or combined surfactants (Triton X-100, Tween 20 and sodium dodecylbenzene sulfonate) both presented better pyrene degradation efficiencies than the system without adding surfactant. After ten weeks, soils planted with V. zizanioides and added with surfactants showed the pyrene degradation efficiencies equal to 85% and 87% (combined) respectively, which showed that 4% and 6% higher rate than the system without adding surfactants (81% ). After twenty two weeks, soils planted with V. zizanioides and added with surfactants showed that the pyrene degradation efficiencies were 96% and 96% (combined) respectively. They were all higher than the system without adding surfactants (94%). Soils planted with R. japonica also showed the same results. In this study, it was also found that the degradation efficiencies were higher at the surface layer of the soil than subsurface layer due to better oxygen content there. Hence the activities of microorganisms in the surface layer were higher than those in the subsurface layer of soils. After twenty two weeks, soils planted with V. zizanioides showed the residual concentration of pyrene were 5.7mg/Kg (surface layer) and 10.8 mg/Kg (subsurface layer). The difference between them was about 50%. Soils planted with R. japonica, T. orientalis or unvegetation also showed the same results. The pyrene concentrations of the roots, stems and leaves were analyzed and the results showed that pyrene did not exist in the plant stems or its leaves. Since pyrene could not be absorbed into plant¡¦s tissues by plants, the phytoextraction and phytovolatilization did not occur in this study. It was concluded that the degradation of pyrene in soils was mainly in rhizoremediation. The soils planted with V. zizanioides showed that the inhibition of Lactobacillus sp, while the soils planted with R. japonica and T. orientalis showed unfavorable conditions to Rhibopus sp.. Four weeks after this experiment, both Lactobacillus sp. and Rhibopus sp. were not existent. The soils planted with V. zizanioides, R. japonica and T. orientalis showed an increase of the number of bacteria (CFU), and thus the pyrene degradation efficiency was increased.

In this study, we used biofuel crops to treat the soils contaminated by heavy oil by using phytoremediation biotechniques. The experiments of this study were divided into tree stages. In the first stage, we simulated real situation, and planted biofuel crops ( soybeans, the sunflower),while the mycorrhizal fungi of Gloums mosseae inoculated the plants in the soils contaminated by oil pollution of fuel (10,000 ppm) artificially. In the soils, the plants were cultivated in pots of 63 days through the experiment. The experiment results revealed that the removal rate of oil was 70%. In the second stage, fuel oil was degraded and tested for the plants of biofuel crops ( soybeans, the sunflower). The specics of Gloums mixed with other species of mycorrhizal fungi were used in the soils contaminated by fuel (5000 ppm) artificially. In the soils, plants were cultivated in a pot of 30 days through the experiment. The experiment result revealed that the fuel oil removal rate was 60% in soils. In the third stage, the seed greasy dirt tolerance experiment were run for the biofuel crops ( soybeans, the sunflower, rape, maize).The fuel oil with three different concentrations (5000 ppm, 10,000 ppm, 30,000 ppm)were used in the polluted soils cultivated in a pot for 30 days through the experiment. The experimental result reveals, that sunflower and maize were found less apt to receive the inhibition of the fuel oil. During the first stage and second stage, the plant species of soybeans inoculated by mycorrhizal fungi, soybean presented significant phytostabilization and rhizodegradation, while the plant species of sunflower inoculated by mycorrhizal fungi also exhibited significant phytoextraction and rhizodegradation. In the future, they can match the other biofuel crops inoculated by different mycorrhizal fungi, which will increase the ability to remove fuel oil in the soil.

Thesis (Ph. D.)--University of Tennessee, Knoxville, 2007. / Title from title page screen (viewed on Sept. 18, 2008). Thesis advisor: C. Neal Stewart, Jr. Vita. Includes bibliographical references.

Six plant species were screened to determine potential suitability for phytoremediation of nitroglycerin (NG), a component in smokeless powders (SP). Seeds of Zea mays (corn), Triticum aestivum (wheat), Medicago sativa (alfalfa), Poa pratensis (Kentucky bluegrass), Trifolium pratense (red clover), and Phaseolus vulgaris (common bean) were sown into greenhouse mesocosms containing commercially prepared soil spiked with 0, 1, and 5% SP (w/w). Soil samples were collected 7, 60, and 90 days after seeding, extracted with ethanol, and analyzed for NG using a gas chromatograph with an electron capture detector. Plant growth observations were recorded using a simple scoring metric at 7, 14, 30, and 60 days after seeding. Soil nitrate and ammonium, potential by-products of NG decomposition, were quantified 90 days after seeding. NG disappearance in plant treatments was markedly, although not significantly (p > 0.05), higher than control at 1% SP, with legumes being the most successful treatment. Nitrate concentrations were significantly (p < 0.05) higher in legume than grass treatments. Soil ammonium was not correlated to any plant or SP treatment. Plant uptake of NG was minimal, suggesting a soil microbial effect in NG disappearance. More extensive screening studies are needed to determine which plants are the most successful remediators of NG. / Department of Natural Resources and Environmental Management

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

As human populations grow worldwide, there is an increasing need to address the problems associated with the creation and disposal of wastes. Although a variety of recent technologies have been shown to be somewhat effective in the remediation of metal contaminated soils, e.g., chemical extraction and stabilization, they are often expensive and labor-intensive. Additionally, these technologies can impart detrimental effects on the chemical and physical properties of the soil under treatment. As an alternative, the less expensive, more environmentally benign use of green plants as tools for the remediation of contaminated soils (phytoremediation) has been studied in recent years.The reported research activities studied the ability of a variety of green plants to extract lead (Pb), cadmium (Ca) and barium (Ba) from metal contaminated soil. Additionally, the researcher studied the degree to which the addition of the synthetic chelate diethylenetriaminepentaacetate (DTPA) and dilute HNO3 affected: the phytoextraction of metals from contaminated soil; the translocation of these metals within study plants; and the effects that the treatments had on biomolecule production in Zea mays, Glycine max, Brassica juncea and Helianthus annuus. A growth chamber study was also conducted to determine if several species of green plants (Ipomoea leptophylla, Lycopersicon esculentum, Capsicum annuum and Tagetes minuta) were capable of hyperaccumulating any of the metals present in the contaminated soil. Additionally, a leachate study was performed to determine the effects that DTPA and HNO3 had on soil Pb mobility rates.Samples were analyzed for Pb, Ca and Ba using FAAS and the data were further analyzed to determine universal measures of variance. While no plants showed overall significant (p=0.05) differences with regard to both treatment and plant part, all species were capable of both accumulating and distributing Pb from the contaminated soil; no plants were able to extract Ba from the soil; some plants extracted trace amounts of Cd in various plant parts. Significant (p=0.05) differences were measured in chlorophyll a, chlorophyll b and carotenoid concentrations with regard to both plant and treatment. Results from the Pb mobility study showed significant (p=0.01) differences in Pb mobility with regard to both treatment and time. / Department of Natural Resources and Environmental Management