Dissertations / Theses on the topic 'Phytoremediation'

Doctor of Philosophy
Department of Biochemistry and Molecular Biophysics
Lawrence C. Davis
Synthetic dyes are capable of producing the whole color spectrum on account of their structural diversity but this diversity poses challenges in the degradation of dyeing wastes. Laccases and peroxidases from bacterial or fungal sources and parts of plants in the presence of hydrogen peroxide (H₂O₂) plus a mediator have been exploited in the bioremediation of synthetic dyes. However, intact plants have not found much favor despite their phytoremediation potential. The goal of this research was to further clarify ways by which whole plants bring about decolorization of different types of synthetic dyes. Hydroponically cultivated plants from two dicot families namely Arabidopsis thaliana and sunflowers (Helianthus annuus) were exposed to representative dyes from several classes: monoazo (Methyl Red and Methyl Orange), disazo (Trypan Blue, Evans Blue and Chicago Blue 6B), and arylmethane (Brilliant Blue G, Bromocresol Green, Malachite Green and Phenol Red). Tests were done in presence or absence of externally added H₂O₂, with or without a free radical mediator, 1-hydroxybenzotriazole, using UV-Visible spectrophotometry. The initial rate of decolorization and the overall percentage decolorization was calculated for each dye in the different treatments. Decolorization of the dyes from different classes varied between plant species and depending on the treatment. Except for Methyl Red, all dyes required added H₂O₂ as well as mediator to achieve rapid decolorization. Added H₂O₂ was found to be the limiting factor since it was degraded by plants within a few hours. Both species were able to slowly decolorize dyes upon daily addition of fresh dye even in the absence of added H₂O₂ and mediator, provided that nutrients were supplied to the plants with the dye. A. thaliana was found to be more effective in dye decolorization per gram tissue than sunflower when treated under similar conditions. Analysis of the residual dye solution by ESI/MS did not reveal any potential by-products following the decolorization treatment with plants, suggesting that the plant roots might be trapping the by-products of dye decolorization and preventing their release into the solution. All these findings support the potential application of whole plants for larger scale remediation.

Master of Science
Department of Horticulture, Forestry, and Recreation Resources
Charles J. Barden
Contaminated water poses a major environmental and human health problem, which may be resolved by using the emerging phytoremediation technology. This plant-based cost-effective approach to remediation takes advantage of the ability of plants to concentrate elements and compounds from the environment, to absorb and transpire large amounts of water, and to metabolize various molecules in their tissues. The city of Manhattan’s Biosolids Farm located near Manhattan, Kansas is using the emerging technology of phytoremediation. The Biosolids Farm remediation began in the mid 1990’s; with a large planting of alfalfa with the goal of absorbing excess nitrates from soil and ground water. In 2004, hundreds of trees were planted, to serve as a protective buffer between the biosolids disposal area and the Kansas River. In 2006, a trench study was installed to improve tree establishment on a sandy outwash area close to the Kansas River using Siberian elm seedlings and rooted cottonwood cuttings from Nebraska and true cottonwood seedlings from Missouri. Treatments included trenching, dairy cattle composted manure, and tree shelters. This planting was done to serve as a vegetative barrier and to aid in reducing nitrate movement into the Kansas River. There were interaction between the tree sources and the trenching, compost and shelter treatments. The treatments showed significant interactions with tree sources with the addition of compost and shelters with a p value of 0.0438, and trenching and compost p-value 0.0021. Tree survival was significantly improved with the use of tree shelters.

Polychlorinated biphenyls (PCBs) contaminate every compartment of the environment including sediments, water, and air. Although their production has ceased, PCBs continue to contaminate the environment. The properties that make PCBs useful in industrial applications are the same properties that cause them to persistent in the environment. Phytoremediation has been proposed as an in situ treatment option for the remediation of these contaminants. Phytoremediation is the use of green plants to mitigate environmental pollution without excavation or treatment of the contaminated material. Hybrid poplar trees may be a feasible treatment candidate for scavenging airborne PCBs from nearby sources. PCBs are scavenged onto the leaves where a majority of the mass remains.

Environmental pollution by metals represents a serious risk to human health and to the environment in both urban, industrial and neighboring areas (Ali et al. 2013). Among natural metalliferous soils, serpentine soils have nutrient scarcity and high concentrations of metals (bioavailable Ni 7-100 mg kg-1; total Ni 500-8000 mg kg-1) (Roccotiello et al., 2015; Turgay et al., 2012). These habitats are inhospitable for the most of the plant species, but highly or exclusively preferred hyperaccumulating plants: these species can live and reproduce on these metalliferous soils without showing toxicity symptoms (Rascio and Navari-Izzo, 2011), being able to accumulate metals such as nickel (Ni) at high concentrations in the aboveground biomass (Krämer, 2010). In some taxa of hyperaccumulators, the concentration of metals and metalloids in the shoot biomass is four orders of magnitude greater than in other non-hyperaccumulating species (Kramer 2010). In these taxa, the rhizosphere, defined as the soil-root interface, plays a key role because it represents the first area of exchange and potential uptake of contaminants, where the roots have free access to the elements of the soil (Alford et al. 2010). Improving the effectiveness of the absorption of metals by the root system of native hyperaccumulators, using the rhizospheric microbiota as a natural chelator of metals, allows increasing phytoextraction with consequent increased potential for environmental restoration and significant economic benefits (Rosatto et al. 2019). This study aims to develop an integrated phytoremediation protocol, employing the facultative Ni hyperaccumulator Alyssoides utriculata (L.) Medik., that was of interest for its environmental plasticity (Roccotiello et al. 2017). This species was inoculated with microbial strains isolated from its rhizosphere: the bacterial strain of Pseudomonas fluorescens SERP1, the fungal strain of Penicillium ochrochloron SERP03S and a mixed inoculum consisting of both strains. These strains, investigated in previous studies developed in collaborations with the Mycology laboratory and the Microbiology laboratory of DISTAV, have been proved to be able to grow in synergy, maintaining the morphological traits typical of each species and reaching maturity, without mutual inhibition (Rosatto et al. 2019). The thesis consists into six thematic chapters: Chapter 1 examines the natural and anthropogenic sources of heavy metals and the risks they pose to human health. In particular, the Nickel element is investigated, being naturally present in considerable amounts in serpentinite soils. The metallophytes and their mechanisms of tolerance and accumulation with respect to metals and the role of Nickel (Ni) in plant physiology are then examined, in regard to hyperaccumulating plants and the physiological mechanisms involved in the hyperaccumulation process. Finally, the processes of phytoremediation and the species used for this purpose are described and the integrated phytoremediation technique, a recently developed technique that involves the use of bacterial and fungal strains as root growth promoters to relieve stress from metals, is explored. The objectives of the current study are subsequently described. Chapter 2 illustrates the soil sampling in the field, the experimental design, the monitoring plan in the different months of the experimentation (t0, t6, t12, t18, respectively) and the parameters measured to evaluate the response of the plants under different treatments (control, single bacterial and fungal inoculum, co-inocula mix of bacterial and fungal strains). The accumulation of leaf Ni is qualitatively assessed with dimethylglyoxime (DMG test). The methodology for the isolation and culture of bacterial and fungal strains is described and the measured biometric and ecophysiological plant parameters are described: fresh and dry biomass, photosynthetic efficiency, and performance index of the plants in the experiment. Chapter 3 illustrates the data obtained and the main results. The data analysis revealed that plants inoculated with a single inoculum (bacterial or fungal), compared to control plants without inoculum, have a greater development of belowground and aboveground biomass but do not show and increased accumulation of Ni. The Student T-test for unpaired samples does not highlight any significant differences for both the photosynthetic efficiency (Fv/Fm) and the Performance Index (PI) between the 'control' group and single inoculated ('Bacteria' and 'Fungi') or co-inoculated plants ('Mix'). Furthermore, the data show that there is no further increase in biomass and physiological response in co-inoculated plants compared to those with single inoculum. Chapter 4 illustrates and discusses the main results obtained, highlighting the potential applicability of the proposed methodological approach in the field. In the end, the conclusions (chapter 5) summarize the main evidence and outline future scenarios. Further studies will validate the effectiveness of selected co-inocula in the field in polymetalliferous soils to understand their potential applicability on a larger scale. The study of the possible use of single inocula and co-inocula in heavy metal hyperaccumulators is currently rising and can significantly contribute to set up more sustainable and effective phytoremediation techniques.

Municipal treated wastewater entering rivers contain biologically active pharmaceuticals capable of inducing effects in aquatic life. Phytoremediation of three of these pharmaceuticals and an herbicide was investigated using Sandbar willow (Salix exigua) and Arabidopsis thaliana. Both plants were effective at removing compounds from solution, with removal of 86% of the synthetic estrogen, 17α-ethynylestradiol, 65% of the anti-hypertensive, diltiazem, 60% of the anti-convulsant, diazepam (Valium®), and 51% of the herbicide atrazine, in 24 hours. Distribution of compounds within roots and shoots, in soluble and bound forms, differed among compounds. Uptake and distribution of pharmaceuticals within the study plants confirmed pharmaceutical behaviour can be predicted based on a physiochemical property, their octanol-water partitioning coefficients. An effective method for detection of 17α-ethynylestradiol within surface water using solid phase extraction and gas chromatography-mass spectrometry was developed. Previously unreported breakdown of 17α-ethynylestradiol into another common estrogen, estrone, during preparative steps and gas chromatography was resolved.
xv, 216 leaves ; 29 cm.

Phytoremediation is a plant-based remediation process for treating contaminated soils. The overall aim of this thesis was to determine whether phytoremediation could be applied to co-contaminated soils. Copper (Cu) and pyrene, and Chromium (Cr) and Benzo[a]pyrene (B[a]P) were used as contaminants. The first study involved the joint effect of Cu and pyrene or Cr and B[a]P on the early seedling growth of Lolium perenne. Results suggest that co-contamination showed several types of interactions for seedling growth with different combinations of the pollutants. The second study involved the role Brassica juncea and Zea mays during the remediation of Cu and/or pyrene, and Cr and/or B[a]P co-contaminated soils respectively. Brassica juncea and Z. mays showed contrasting results for metal and polycyclic aromatic hydrocarbon (PAH) remediation. The third study compared freshly spiked soils and aged soils. Ageing affected the plant biomass, metal phytoextraction and PAH dissipation in different ways when compared to fresh soils. Finally, the efficiency of ethylenediaminetetraacetic acid-EDTA and/or citric acid as chelators in co-contaminated soils was studied. The combined application of EDTA and citric acid was more effective in co-contaminated soils. The overall findings from the four studies suggest that phytoremediation could be applied to co-contaminated soils.

Research was conducted to develop a cost effective and environmentally friendly technology to limit the dispersal of metal contaminants from highway traffic in the soil to the surrounding natural environment. The study comprised preliminary field measurements followed by two pot experiments and a field study. The first study evaluated the phytoextraction/ phytostabilisation potential of five plant species: Brassica napus L (rape), Helianthus annuus L. (sunflower), Lolium perenne L (perennial rye grass), Poa pratensis L (Kentucky blue grass) and Festuca rubra L (creeping red fescue) for metals (Cu, Mn, Pb and Zn), in soils with different metal contamination levels. The promising plant species identified were Lolium perenne, Festuca rubra and Poa pratensis. Total soil and plant metal concentrations, as well as the relative metal partitioning in different soil fractions and in plants were determined to provide an estimate of the mobility and potential bioavailability of metals in the soil. The second study evaluated the effectiveness of soil-plant-amendment interaction in immobilising metals in the soil. The amendments included lime, phosphate and compost individually and in combination, and were applied to the plant species: Lolium, Poa and Festuca. Maximum metal immobilisation was achieved in the soil by the combined application of amendments in conjunction with growth of Festuca for Cu, Poa for Pb and Zn and Lolium for Mn. The results obtained from first and second studies were confirmed by conducting field studies. A completely randomized factorial experiment in split plot design with three plant species (Lolium, Poa, and Festuca) individually and in combination, with and without soil amendments was conducted along Highway 17 soil in southwest British Columbia. The influence of root-soil interactions and seasonal influence on the solubility and bioavailability of metals in the soil with and without soil amendments was also evaluated. The best management practices (BMP) developed from the study have the applicability for phytostabilisation of metal contaminated sites and can be suggested as a risk management activity, reducing long-term associated risks.

In two pot experiments using two different crop ryegrass (Lolium perenne) and two flax (Linum usitatissimum) varieties Viola and Elise, ryegrass decreased in the pool of heavy metals compared with bare soil using EDTA as extractant. NH4+ decreased the soil pH, increased EDTA-extractable Zn and increased the Zn uptake. Lime addition increased the pH and depressed Zn uptake. The pool of extractable EDTA was not changed by growing both of the flax varieties. Lime increased EDTA-extractable Cu and Pb significantly, but decreased the Zn, and pH increased in this order NH4+NH4++lime>NH4+>NO3-. Ammonium decreased the pH more than other treatments. In agar using Bromocresol purple indicator NH4+ increased the pH in the rhizosphere of different plants. With two different initial pH treatments (7 and 3.2) the NH4_ decreased the pH in the rhizosphere at high initial pH 7 and maintained the low pH at initial pH 3.2 to 4 against the buffer capacity. At different initial pH 4, 5, 6, 7 and 8 the ammonium decreased the high pH and maintained the low pH, but NO3- had no effect on the pH. Ammonium increased the toxicity of Zn due to pH decreases. There was no effect of both nitrogen sources NH4+ or NO3- on rhizosphere pH when applied as a foliar application. These indicated that the NH4+ can decrease the pH in the rhizosphere of plants and could play an important role in manipulation of the rhizosphere bioavailability of heavy metals. Toxicity of the three metals is Cu>Pb>Zn in this order and the crops tolerance is following this order pea>flax>barley. An agar-Hoagland nutrient solution contaminated with two soils, sewage treated soil (SBS) and galena soil (G), was used with flax as a test crop. The ammonium treatment lowered the pH in both soils, but with galena treated greater than SBS soil, this is attributed to the buffering capacity of the SBS soil. Averaged over all the concentrations the NF4+ treatments resulted in higher Zn shoot content that NO3- treatment, while in Cu shoot content nitrate was more than ammonium. The transfer factor of lead with ammonium treatment was greater than nitrate treatments at the 0.1 and 0.25% galena and the transfer factor of the Zn and Pb more than Cu in all treatments. At high initial pH 8 and high concentration of Zn and Cu barley grew well and this is attributed to immobilisation of Zn and Cu compared with low pH 5 and 6.5 where the barley plant did not survive. Ammonium lowered the high pH 8 and caused lower biomass production of barley than nitrate.

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

Food security and eutrophication are two issues proven to have severe impacts on both humanity and the environment. This study suggests improving the local food security by utilizing phosphorus and nitrogen, available in severe eutrophic small lakes, in local food production, thus turning eutrophication from a problem into a resource. The study theoretically experiments the possibility of using eutrophic water in a greenhouse, where hydroponics is used as a cultivation method. The eutrophic water is pumped from the lake into the greenhouse, and then to the hydroponic system, which is expected to remediate the water, returning clean water to the lake. The objective of this process is to phytoremediate eutrophic water and simultaneously, produce edible commercial plants. Finding the best matching lake and plant nitrogen to phosphorus (N:P) ratio, is of key importance to optimize the remediation process. Based on data from a literature review, edible plants N:P ratios are found lower than typical lake N:P ratios, suggesting that, in some cases, edible plants in the hydroponic system would require additional nutrients to grow optimally. Finding the best matching lake and plant N:P ratio is thought to optimize the remediation process. Matching the lake and plant N:P ratio was conducted in Python.

Heavy metals pollution has become a global problem in all industrialized countries. Since the industrial revolution, a continuous release of heavy metals has led to a severe contamination of the soil. There are many techniques available for the remediation of contaminated soils, that to date represent a constantly evolving field, absorbing a lot of resources for research and development. Phytoremediation is a technique that uses plants to clean up metals and other contaminants from the soil or to make them harmless or less dangerous. Cynara cardunculus L. (cardoon), a perennial species from Asteraceae family, native to Mediterranean countries, is a crop studied as a metal accumulator in several researches. In this work, two experiments were performed to evaluate the effects of Cadmium (Cd) and Arsenic (As) on growth of different cardoon subspecies and to determine if this crop can be used for the remediation of polluted soils, combining this application with energy production. Different As and Cd concentrations were tested in Cynara cardunculus L. var. altilis in Experiment 1, with the aim to study the biological response of cardoon to heavy metals stress. In cardoon, the biomass production and Cd and As concentrations were determined in 4 different stages of the biological cycle in different parts of plant. The results showed that the cardoon was a plant that could tolerate the presence of Cd and As, even in high doses. Under Cd treatment, the Cd concentration decreased in the roots while increased in the leaves over time. Under As treatment, the As concentration in cardoon tissues increased with increasing As concentration; in particular the plants showed a several reduction in the production of biomass and the highest dose of As caused the death of the plants. In the combined Cd and As treatments, the plants improved resistance to As and Cd and the presence of Cd increased the ability of cardoon to tolerate As up to 45 days after artificial contamination. In the second study (Experiment 2), three accessions belonging to var. altilis (Gen 1) and var. sylvestris (Gen 2 and Gen 3) were compared and different concentrations of As, Cd and As+Cd were used. The aim of this work was to assess the concentration and bioaccumulation of As and Cd in the soil and in different parts of the plant, to understand the effects of Cd and As comparing different varieties and genotypes of cardoon plants and to study the specific speciation of As and Cd into plants. The results showed that plants were considerable tolerant to Cd and As, suggesting that this species was able to tolerate low doses of these toxic elements. Moreover, as shown in the values of bioaccumulation factor, cardoon plants had the ability to accumulate large quantities of metal contaminants in its tissue. The results regarding the speciation of As and Cd suggested that exposure of plants to toxic metals appeared to induce the synthesis of sulfur-rich ligands such as phytochelatins, a cysteine-rich oligopeptide, that strongly bound metals. The presence of As upregulated the production of these specific proteins/ligands that bound and traslocated Cd into the plant tissue suggesting that the two metals interacted to magnify phytochelatin production, leading to sequestration of both metals and consequently increasing the tolerance to both. In conclusion cardoon was a plant that could tolerate the presence of heavy metals including Cd and As. The combination of As+Cd treatment, however, increased the resistance of plants allowing them to survive. Furthurmore, Cynara Cardunculus var. sylvestris was the best subspecies that could tolerate high levels of As and Cd in its tissues and bioaccumulate greater concentrations of both metals than var. altilis. It would be useful to continue the trials with the selected Genotype 3 in future works, with the aim to test for more years, its remediation efficiency in polluted soils and exploit its biomass for energy purposes.

L’inquinamento dei suoli da metal(loid)i è un problema ambientale globale che ha gravi conseguenze sulla salute umana, animale, vegetale e dell’ecosistema. Nel corso degli anni, sono state utilizzate diverse tecnologie per il trattamento di suoli contaminati da metal(loid)i. Per la decontaminazione di suoli inquinati, un’attenzione sempre maggiore è stata rivolta all’impiego della strategia del fitorimedio assistito, poiché questa tecnica offre protezione ambientale a basso costo e può essere applicata a vaste aree contaminate. Tuttavia, l’efficacia del fitorimedio assistito di suoli contaminati da metal(loid)i è influenzata da diversi fattori: caratteristiche ambientali, proprietà del contaminante, tipologia dell’ammendante utilizzato, attività microbica del suolo, specie vegetali impiegate. Questa tesi si è avvalsa di sperimentazioni sia di ricerca applicata che ricerca di base, e gli obiettivi principali sono stati: (i) capire in che modo diversi fattori influenzano il potenziale dell’approccio del fitorimedio assistito; (ii) comprendere i meccanismi coinvolti nelle interazioni tra piante, ammendanti, microrganismi e suolo contaminato nel processo del fitorimedio assistito. Nell’ambito della ricerca applicata, sono state condotte due sperimentazioni, al fine di fornire informazioni sull’impiego di metodi alternativi di fitorimedio assistito di terreni contaminati da metal(loid)i. La prima sperimentazione ha previsto l’utilizzo di tre diverse specie vegetali appartenenti alla famiglia delle Salicaceae e due diverse modalità di applicazione di un ammendante del suolo (il biochar). Questo studio ha illustrato come diverse specie vegetali e differenti strategie di applicazione di un ammendante del suolo possano influenzare l’efficacia del fitorimedio assistito di un suolo inquinato da elevate concentrazioni di arsenico. La seconda sperimentazione, invece, è stata incentrata sulla capacità di fitorimedio della specie di trifoglio Trifolium repens e sull’impiego di differenti combinazioni di diversi ammendanti per il trattamento di un suolo multi-contaminato. I dati di questa seconda ricerca hanno mostrato come, sulla base delle caratteristiche dei metal(loid)i e delle proprietà fisico-chimiche del suolo, sia importante selezionare una determinata specie vegetale e utilizzare una corretta combinazione di ammendanti (prestando attenzione sia al tipo di ammendante utilizzato che alla sua percentuale di applicazione al suolo). Nella sperimentazione concernente la ricerca di base, la pianta modello Arabidopsis thaliana è stata fatta crescere su un suolo contaminato da arsenico e piombo ed ammendato con biochar e batteri, con lo scopo di comprendere i meccanismi molecolari alla base della tolleranza delle piante allo stress da metal(loid)i. Per decifrare i processi biologici che hanno permesso una migliore crescita delle piante di Arabidopsis nel suolo con la combinazione di biochar ed inoculo batterico, questo studio si è avvalso di un’approfondita analisi di proteomica assistita dalla bioinformatica. Presi insieme, i dati di questa tesi hanno fornito importanti suggerimenti su come utilizzare diverse combinazioni di ammendanti del suolo e microrganismi nelle strategie di fitorimedio assistito, al fine di trattare in maniera efficace i suoli contaminati da inquinanti inorganici. Inoltre, i risultati ottenuti sulla pianta modello hanno permesso l’ampliamento delle conoscenze sulle complesse interazioni che si verificano tra contaminanti, piante, ammendanti del suolo e microrganismi in aree inquinate da alte concentrazioni di metal(loid)i. Tali informazioni potrebbero essere applicate nella selezione e nella gestione delle specie vegetali, delle tipologie di ammendanti e delle comunità microbiche del suolo per migliorare la sinergia pianta-ammendante-microrganismi, incrementare la crescita delle piante e la loro capacità di tollerare stress biotici e abiotici e, di conseguenza, migliorare l’efficacia dei programmi di fitorimedio per la bonifica di aree contaminate da metal(loid)i.
Metal(loid) contamination of soils is a global environmental problem with serious consequences on human, animal, plant and ecosystem health. In the course of the years, various technologies have been used to treat and remediate metal(loid) polluted sites. Assisted phytoremediation strategy for contaminated soils has attracted increasing attention since it offers environmental protection at low cost, and it can be applied to a large area. However, the efficiency of assisted phytoremediation of metal(loid) contaminated soils depends on environmental features (e.g., type, pH and nutrient content of soil), contaminant characteristics, amendment types, microbial activity, plant species, and interactions between all these aspects. Thus, the main objectives of thesis, related to applied and basic research, were to understand: (i) how different factors influence the effectiveness and the potential of assisted phytoremediation approach, and (ii) the mechanisms involved in the interactions between plants, amendments, microorganisms, and contaminated soil in assisted phytoremediation process. To accomplish the objectives of the applied research, two experiments were carried out with the goal of providing insights for use of alternative methods for assisted phytoremediation of metal(loid) contaminated soils. The first experiment was conducted using three different Salicaceae species and two diverse strategies of the same soil amendment. This experiment gave an outline about the influences of plant species and amendment application procedure on the assisted phytoremediation of a soil heavily polluted by only one metalloid (arsenic). The second experiment was focussed on the phytoremediation ability of a clover species and the need to use a combination of different amendments for the treatment of a multicontaminated soil. On the base of metal(loid) characteristics and soil physicochemical properties, experiment data showed the importance to choose a specific plant species and a correct combination of amendments (both in regarding to the amendment type and application rate). In order to understand molecular mechanisms underlying plant tolerance to metal(loid) stress, plant-soil microorganism interactions and amendment effects, investigations were carried out by using the Arabidopsis thaliana model plant grown on a polluted soil added with amendment and bacteria. An in-depth bioinformatics-assisted proteomics analysis was also used for deciphering the biological processes which allowed the better growth of Arabidopsis plants, in the soil with amendment/bacteria combination. Taking together, data of this thesis provided important suggestions on how to use different combinations of amendments and microorganisms in assisted phytoremediation strategies in order to efficiently treat soils contaminated by inorganic pollutants. Furthermore, results obtained on the A. thaliana model plant contributed with new information in broadening the knowledge on the complex interactions occurring among contaminants, plants, soil amendments, and microorganisms in areas polluted by high concentrations of metal(loid)s. Such information might be applied in the selection and management of plant species, amendment types, and soil microbial communities to ameliorate plant-amendment-microbe synergy, increase plant growth and tolerance to biotic and abiotic stresses and, consequently, enhance the efficiency of phytoremediation programs to restore metal(loid) contaminated lands.

Human activities are responsible for the release of pollutants into the environment, and soil contamination by metals and metalloids is of primary concern. Currently, the laws covering environmental management and protection of several countries are focusing on the less expensive and more environmentally friendly biological methods of restoration, compared with the more invasive physico-chemical ones. The present study regards the first attempt in Italy to apply in situ phytoremediation of a metal-polluted, markedly degraded area located at Torviscosa (Udine, NE Italy) and included in the national priority list of sites for restoration. Within the site, pyrite cinders, derived from mineral roasting for sulphur extraction, had been severely contaminated by various metals such as arsenic, cadmium, copper, lead and zinc. The wastes were discharged in the Thirties and covered with an unpolluted 0.15-m layer of gravelly soil. Because of the particular substrate composition, poor physical structure, nutrient deficiency, and extreme hydrological conditions, the site was colonised by a rare and inadequate vegetation cover. Application of phytoremediation with biomass species required particular care in soil management and adjustment of the cultivation method. In this regard, ploughing was compared with subsoiling, in order to dilute the cinders with the unpolluted top layer and to maintain a shallow favourable layer for plant establishment, respectively. In situ, trials were carried out to compare woody species (Populus alba L., P. nigra L., P. tremula L., Salix alba L.) and crops (Helianthus annuus L., Lolium multiflorum Lam., Medicago sativa L., Raphanus sativus L. var. oleiformis Pers.) in terms of above-ground productivity and metal accumulation, and to establish the role of root colonisation. Greater root lengths were generally correlated with metal concentrations in plant tissues but not with mass removals. The excessively high metal concentrations, both total and DTPA-extractable, of the wastes in ploughing cause worse rooting than subsoiling in almost all species. In both woody and crop species, the mass balance of phytoextraction mainly involved Zn and was relatively poor because of generalised impaired growth. However, poplar and willow were able to stabilise a considerable fraction of trace elements at below ground, making the application of phytostabilisation (coarse roots) through short-rotation coppicing a reliable complementary strategy. Instead, this possibility seems less practicable in herbaceous crops through their finer roots, although more precise quantification of root production and turnover is required for insights into long-term metal stabilisation in tap-rooted species. Results obtained at the Woolston New Cut Canal in the UK, which are an integral part of this thesis, indicate that stabilisation of several metals can also be achieved by adding soil with a small percentage of cement (1%) or lime (1%). This would reduce risks of metal movements through windblow and leachate transfer, and allow plants to improve their above-ground productivity. Among crops, Raphanus sativus var. oleiformis showed the highest tolerance to pyrite wastes, providing interesting phytoextraction balances, thanks to less altered growth rather than increased metal concentrations. The consistency of these results with past experiments in another polluted site suggested that this species can be conveniently exploited by testing various methods of improvement in metal uptake (e.g., auxins, humic acids, chelators). In pot trials, repeated soil applications of indolebutyric acid (IBA) have shown detrimental effects on plant growth and phytoextraction, regardless of doses of 0.1 and 1 mg kg-1. These negative effects were not observed for foliar spraying at 10 IBA mg L-1. Conversely, significant increases in root length and metal removal were seen after soil application of humic acids (HA) at small doses (0.1 g HA kg-1 of substrate), probably because of their hormone-like and chelating (weak) effects. Higher doses of HA (1 g kg-1), an extremely expensive option on a large scale, were fortunately not effective, as worsening of shoot biomass greatly exceeded improvements in metal concentrations. The application of ethylene-diamine-disuccinic acid (EDDS), a less persistent and more easily degraded chelator than the traditional ethylene-diamine-tetraacetic acid (EDTA), was experimented in both Raphanus sativus var. oleiformis and Brassica carinata A. Braun, but only occasionally were good phytoextraction results observed. EDDS always improved metal concentrations, regardless of doses of 2.5 and 5 mmol kg-1 (applications close to harvest), but biomass reduction was a prevailing effect. Repeated low-dosage applications of EDDS (1 mg kg-1 × 5 times) during the cycle, another possible strategy of chelator management, was less effective because of considerable phytotoxitoxicity and undesirable marked increases in metal leaching. Like those found for other chelators, these results suggest that, for maximum effectiveness and absence of environmental risks, EDDS should be applied one week before harvest at a moderate dose (2.5 mmol kg-1), regardless of species. It is concluded that phytomanagement of metal-polluted sites with field crops and coppices undoubtedly has a landscape value, but may only seldom become a reliable phytoextraction strategy in extreme contamination conditions like those due to pyrite wastes. In these circumstances, phytostabilisation is an option which should be evaluated more carefully as additional complementary mean. For both phytoextraction and stabilisation, the proper choice of species and adjustment of its cultivation method, as well as substantial soil amelioration and identification of specific treatments, can significantly improve these green technologies.
Le attività civili, industriali e agricole sono responsabili del rilascio di inquinanti nell’ambiente. Tra le diverse fonti, la contaminazione del suolo da parte di metalli e matalloidi è una problematica di grande attualità. Contestualmente, la legislazione in materia di gestione e protezione ambientale di molti Paesi attribuisce alle tecnologie di bonifica biologiche, meno costose e di minor impatto ambientale, una rinnovata importanza, al pari dei più invasivi metodi di depurazione fisico-chimici. Il presente studio riguarda il primo tentativo in Italia di applicazione della fitodecontaminazione in situ di un’area – sita a Torviscosa, Udine – marcatamente inquinata da metalli e inclusa nell’elenco nazionale dei siti prioritari per la bonifica (D.M. 468/2001). A partire dagli anni Trenta e per diversi anni, nel sito sono state scaricate ceneri di pirite derivanti dall’arrostimento del minerale pirite per l’estrazione dello zolfo. Le ceneri sono risultate marcatamente contaminate da vari metalli come arsenico, cadmio, rame, piombo e zinco. A termine del periodo industriale, lo scarto industriale è stato ricoperto con uno strato di 0,15 m di terreno di riporto non inquinato ma ricco in scheletro. A causa delle particolari caratteristiche negative del substrato, struttura fisica alterata, carenza di nutrienti e delle sfavorevoli condizioni idrologiche, la flora spontanea che ha colonizzato negli anni il sito è risultata essere rada e inadeguata allo svolgimento di un efficiente processo fitoestrattivo. La realizzazione dell’impianto di fitoestrazione con specie da biomassa ha richiesto una cura particolare nella gestione del suolo e un adeguamento delle tecniche di coltivazione. In merito alla lavorazione del terreno, la coltivazione delle piante è avvenuta dopo aratura ed in comparazione con tecniche di ripuntatura, rispettivamente al fine di diluire le ceneri con il terreno di riporto e di mantenere uno strato superficiale non inquinato. In situ sono state coltivate specie arboree (Populus alba L., P. nigra L., P. tremula L., Salix alba L.) ed erbacee di interesse agrario (Helianthus annuus L., Lolium multiflorum Lam., Medicago sativa L., Raphanus sativus L. var. oleiformis Pers.), valutando la produzione di biomassa, l’accumulo di metalli ed il possibile ruolo dell’apparato radicale. In generale, un maggiore accrescimento radicale (lunghezza) è risultato correlato positivamente alla concentrazione di metalli raggiunta nei tessuti epigei, ma non con la loro rimozione. Nelle ceneri, l’aratura ha peggiorato l’accrescimento radicale di quasi tutte le specie saggiate a causa della maggiore presenza (totale e biodisponibile) di metalli rispetto alla ripuntatura. Nel sito di Torviscosa, l’asportazione di inquinanti è risultata generalmente modesta a causa della scarsa produttività vegetale, e ha riguardato quasi esclusivamente lo zinco. Pioppo e salice sono stati comunque in grado di stabilizzare una porzione considerevole di metalli pesanti a livello radicale, suggerendo che i sistemi SRC (Short Rotation Coppice) possano fornire anche un importante contributo nella fitostabilizzazione. Questa possibilità sembra invece essere meno realistica per le radici fibrose delle colture erbacee, a causa del loro intenso e rapido turnover. Si rende tuttavia necessaria una precisa quantificazione della produttività radicale e del tempo di ritenzione dei metalli nelle radici fittonanti. I risultati ottenuti presso il Woolston New Cut Canal (Inghilterra, UK), parte integrante di questa tesi, indicano che l’ammendamento della matrice inquinata con piccole quantità di cemento (1%) o di carbonato di calcio (1%) può contribuire a stabilizzare diversi metalli pesanti. Questo ridurrebbe la dispersione atmosferica e il dilavamento degli inquinanti, permettendo allo stesso tempo alle piante di migliorare la produttività per effetto della minore frazione di metalli biodisponibili. Tra le colture saggiate, il rafano (Raphanus sativus var. oleiformis) ha dimostrato un elevato grado di adattamento alle ceneri di pirite, raggiungendo un buon potenziale produttivo e interessanti asportazioni di metalli. L’interesse per questa specie è stato pertanto esteso anche a sperimentazioni in ambiente controllato per studiare l’applicazione di auxine, acidi umici e sostanze chelanti. L’applicazione ripetuta al suolo di acido indolbutirrico (IBA) non ha fornito i risultati attesi avendo ridotto l’accrescimento vegetale e l’accumulo di metalli sia a 0,1 che 1 mg IBA kg-1. L’ormone ha invece fatto incrementare la lunghezza radicale tramite applicazioni fogliari a 10 mg IBA L-1. Stimolazione dell’accrescimento radicale e miglioramenti del bilancio fitoestrattivo sono stati ottenuti con modeste applicazioni al suolo (0,1 g kg-1) di acidi umici (HA), verosimilmente per l’attività ormono-simile e del debole effetto chelante. Dosi superiori di HA (1 g kg-1), un’opzione estremamente costosa su larga scala, non sono risultate efficaci, a causa del prevalente effetto fitotossico. L’applicazione di acido etilendiaminodisuccinico (EDDS), un chelante meno persistente e più facilmente biodegradabile del ben noto acido etilendiaminotetracetico (EDTA), è stata sperimentata sia in Raphanus sativus var. oleiformis che in Brassica carinata A. Braun, ma solo raramente si sono osservati miglioramenti della fitoestrazione. L’EDDS ha infatti sempre aumentato la concentrazione di metalli nei tessuti epigei, indipendentemente dalla dose (2,5 e 5 mmol kg-1) applicata poco prima della raccolta, ma la riduzione di biomassa è stata più marcata. Un’altra strategia possibile di gestione del chelante, ovvero applicazioni ripetute a basso dosaggio durante il ciclo colturale (1 mmol kg-1 × 5 volte), è risultata meno efficace a causa della considerevole fitotossicità e dell’aumento incontrollato di metalli lisciviati. Questi risultati suggeriscono che l’EDDS, analogamente ad altri chelanti, possa essere applicato proficuamente e senza rischi ambientali una settimana prima della raccolta a dosi moderate (2,5 mmol kg-1), indipendentemente dalla specie vegetale considerata. Si può concludere che la gestione di siti inquinati da metalli pesanti tramite coperture vegetali agrarie e forestali possiede indubbiamente un importante valore paesaggistico, ma solo raramente può diventare una strategia concreta in condizioni estreme come quelle causate dalle ceneri di pirite. In queste circostanze la fitostabilizzazione è un’opzione da valutare con attenzione ed in termini di complementarietà alla fitoestrazione. Una corretta scelta delle specie e il perfezionamento delle tecniche agronomiche, così come il miglioramento delle condizioni chimico-fisiche della matrice inquinata e l’individuazione di trattamenti specifici, possono tuttavia rendere queste tecnologie ecocompatibili più efficaci e applicabili su larga scala.

The sources of renewable energy acquire considerable interest, if accompanied by a more rational use of energy, to facilitate the transaction by a high use of fossil fuels to a sustainable use of renewable energy. There are many alternative energy source such as wind, solar, geothermal and biomass that fulfil the criteria of sustainability and economic feasibility. Biomass refers to all the vegetable matter that can be obtained from photosynthesis. Biodiesel can be produced from a variety of feedstock; they are renewable, sustainable, biodegradable, and environmentally friendly. Decentralized wastewater treatment systems are designed to operate at small scale; they not only reduce the effects on the environment and public health but also increase the ultimate reuse of wastewater depending on the community type, technical options and local settings. Used effectively, it promote the return of treated wastewater within the watershed of origin. Aquanova is a flexible system of decentralized processing in which every single supply in term of water resources, organic substance and energy and its subsequent disposal, once it has finished its function (wastewater sewerage, solid waste) is considered as a part of the close loop of the sustainable management. Aquanova provides for the source separation of municipal wastewater in three separate streams (brown waters, yellow waters and grey water) through the use of special toilet. The yellow and grey waters are treated in a wetland system, considered a low energy demand and limited environmental impact technology; these phytotreated waters can be reused for toilet flushing. Landfill leachate can be defined as the liquid produced from the decomposition of waste and infiltration of rainwater in a landfill; it contains heavy metals, salts, nitrogen compounds and various types of organic matter. Generation of leachate occurs when moisture enters the refuse in a landfill, dissolves the contaminants into liquid phase and produces moisture content sufficient to initiate liquid flow. Leachate varies from one landfill to another, and over space and time in a particular landfill with fluctuations that depend on short and long-term periods due to variations in climate, hydrogeology and waste composition. Phytoremediation is characterised by biological type treatments, in which the plants growing in water-saturated soil develop a key role for direct action of the bacteria that colonize the root system and rootstock. Practically, it consists of mitigating pollutant concentrations in contaminated soils, water or air with plants able to contain, degrade or eliminate contaminants. It has the advantage to be an in situ technology, but on the other hand it is a quite slow process as it is dependent on a plant's ability to grow in a stressed environment that is not ideal for the normal plant growth. The use of phytoremediation is one possibility to develop an economically and environmentally sustainable management of waste and polluted sites, which is raising interest in recent years. The present research tested different wastewater streams, by the use of the decentralized Aquanova systems for the domestic wastewaters and landfill leachate. The wastewaters were treated through phytoremediation facilities; for each case of study it has been proposed oleaginous plants- known as energy crops- as species for the phytotreatment; subsequently the cultivated seeds were considered as suitable biomass for the production of biodiesel in a short time. All these aims were developed in four experimental phases; a greenhouse was used to control the temperature and the light exposition of the plants. The first phase proceed with the phytotreatment using six 300 liters tanks filled with 10 cm coarse gravel and 30 cm of mixture soil, chosen the following crops: Helianthus annus (H), Glycine max (G) and Brassica napus (B). The wastewater components (grey and yellow waters) have been separated through the toilet facilities of the Aquanova project implementation at the LISA laboratory, as mentioned before. Half of the tanks were irrigated with increasing percentage of grey and yellow waters (0.1-3.5% YW and 99.9- 96.5% GW), and the other half with tap water as control units. In the second phase, old landfill leachate was used as irrigation water. Coarse gravel was arranged in 10 cm drainage layer on the bottom of each pot; pure sand in half pots and a mixture of sand and clayey soil in the other half pots were used to build up a 30 cm deep growing layer. Half of the pots were irrigated with increasing leachate concentrations (2-30 % Leachate; 90 – 70% tap water), and the other half with tap water as control units. Brassica napus grew slowly compared to the other vegetal essences and it did not produce any flower and it was favoured by sand, rather than soil substrate; their response ca be attributed at the captivity inside the greenhouse. According to the results obtained in the two previous phases, in the third phase Brassica napus was not used anymore. Here, the seeds (H & G) were germinated in LISA laboratory under controlled conditions, using different kinds of substrate and different leachate dilution in order to test the maximum leachate percentage to be used in the irrigation. Glycine max seeds presented better germination at 5% of diluted leachate and in sand substrate, while Helianthus annus seeds had a better germination on soil mixed with concentrated solutions at 10% to 20% of leachate. The irrigation water was decided as a mixture of 20% leachate and 80% grey water. The same greenhouse and the same pots were used, half of those irrigated only with tap water as control. Last experimental phase was performed in the same (eight) tanks used in phase 1 (four for each species, Helianthus annus and Glycine max) inside the greenhouse. Six tanks were irrigated with the leachate mixture (10 - 60% leachate and 90 - 40% tap water) and the other two with tap water as control. The results of the whole research can be summarized as removal efficiencies of each tested analytical parameter. Analysis was performed in double. Mass balance of the two representative parameters as nitrogen and phosphorus was performed. The phytotreatment did not inhibit the growth of the species: in fact the energy crops produced bigger biomass and roots length with wastewater feeding rather than with tap water in each experimental phase, in similar way with the production of seeds. Nutrient removal by the plants was fully effective until the flowering point and after that, removal rates started decreasing. As grey water revealed lacking in nutrients, the increasing percentage of urine until 3.5 % in the feeding (phase 1), was crucial for the growth of the plants. The percentage of 20% leachate in the mixture has showed the best results in terms of growth of the plants and Nitrogen & Phosphorus removal efficiencies. The sand was not a good substrate for the growth of the plants, even if the irrigation water was leachate, rich in nutrients, except for Brassica napus. With mixed soil, better performances in removal rates were obtained
Per far fronte alla crescente necessità di sostituire i combustibili fossili come risorsa energetica si sta ponendo sempre più attenzione all’utilizzo delle sorgenti rinnovabili soprattutto se accompagnato da un uso razionale dell’energia stessa. Tra le sorgenti di energia alternative ormai note come il vento, il sole e la geotermia, anche le biomasse soddisfano i principali criteri di sostenibilità ed di fattibilità economica. Per biomasse si intende tutta quella materia di origine organica che può essere ottenute dalla fotosintesi. I sistemi di trattamento delle acque decentralizzati sono progettati per lavorare su piccola scala; essi non solo riducono l’impatto sull’ambiente e sulla salute pubblica, ma massimizzano anche il riuso dell’acqua di rifiuto per diversi scopi che dipendono dal tipo di comunità fruitrice del servizio, da opzioni progettuali o dalle località in cui vengono costruiti. Questo riuso delle acque reflue, se utilizzato in modo efficace, favorisce il ritorno delle acque trattate all'interno del bacino di origine. Il Sistema Aquanova è un sistema di trattamento delle acque decentralizzato e flessibile nel quale ogni singolo flusso in termini di risorsa d’acqua, sostanza organica ed energia ed il suo smaltimento finale è considerato come parte di un ciclo chiuso di un sistema di gestione sostenibile. Il Sistema Aquanova prevede la separazione delle acque di rifiuto civili in tre flussi: acque grigie, acque brune e acque gialle (separate tra loro attraverso l’uso di una speciale toilette). Le acque grigie e quelle gialle sono trattate in un sistema assimilabile ad un’area umida; questo fitotrattamento delle acque permette il riutilizzo delle acque reflue negli sciacquoni delle toilette. E’ sistema che si avvale di una tecnologia a basso consumo energetico e con un impatto ambientale limitato. Il percolato di discarica, può essere definito come il liquido prodotto dalla decomposizione dei rifiuti e infiltrazioni di acqua piovana in una discarica, contiene metalli pesanti, sali, composti azotati e vari tipi di materia organica. La generazione del percolato avviene quando l'umidità entra i rifiuti in una discarica, dissolve i contaminanti in fase liquida e produce umidità sufficiente per avviare il flusso del liquido. Il percolato varia da una discarica all'altra e nello spazio e nel tempo in un particolare discarica con oscillazioni che dipendono da periodi di breve e lungo termine, a causa di variazioni climatiche, idrogeologia e dei rifiuti composizione. La tecnica della fitodepurazione consiste nell’abbassare le concentrazioni di inquinanti in suoli, acqua o aria contaminati con piante in grado di assorbire, degradare o eliminare i contaminanti stessi. E’ una tecnica caratterizzata da trattamenti di tipo biologico, nei quali le piante, che crescono su un suolo saturo d’acqua, sviluppano un ruolo chiave per l’azione diretta dei batteri che colonizzano il sistema radicale. Oltre ad essere un trattamento in situ, è caratterizzato da un processo lento che dipende dall’abilità delle piante di crescere in un ambiente stressato e non ideale per la loro crescita. Negli ultimi anni si sta guardando all’utilizzo di questa tecnica come alla possibilità di sviluppare un sistema di gestione delle bonifiche dei siti contaminati e delle discariche sostenibile sia dal punto di vista economico che ambientale. Questo lavoro di ricerca ha voluto testare, con l’ausilio del Sistema Aquanova, la tecnica della fitodepurazione, utilizzando piante oleaginose (note come energy crops) irrigate con diversi reflui e fatte crescere in serra per poter controllare la temperatura e l’esposizione luminosa delle piante. Sui semi ottenuti dalle varie essenze sono state effettuate alcune analisi per testare la loro come materia prima per la produzione di biodiesel. Il lavoro è stato sviluppato in quattro fasi sperimentali. Nella prima fase sono state usate sei vasche da 300 litri contenenti 10 cm di ghiaia grossolana, posti sul fondo come strato drenante, e 30 cm di suolo misto, su cui sono state fatte crescere le seguenti piante: Helianthus annus, Glycine max and Brassica napus. Le componenti del refluo usato per l’irrigazione (acqua grigia e acqua gialla) sono state separate attraverso la toilette utilizzata nel Sistema Aquanova che si trova presso il laboratorio LISA del Dipartimento ICEA. La metà delle vasche è stata irrigata con percentuali crescenti di acqua grigia (99.9-96.5%) e acqua gialla (0.1-3.5%), mentre l’altra metà è stata irrigata con acqua di rete ed usata come controllo. Nella seconda fase sono stati usati dei vasi contenenti tutti 10 cm di ghiaia grossolana, posti sul fondo come strato drenante, e 30 cm di suolo diverso: metà dei vasi sono stati riempiti con solo sabbia, l’altra metà con una miscela di sabbia e terreno argilloso. Metà dei vasi è stata irrigata con acqua di rete miscelata a percentuali crescenti di percolato di una vecchia discarica (2-30 %), mentre l’altra metà è stata irrigata con acqua di rete ed usata come controllo. Le essenze piantate sono state le stesse della prima fase. Alcune di esse, come la Brassica napus, piantate sulla sabbia sono cresciute più lentamente delle altre e senza produrre fiori: questo comportamento può essere attribuito alla crescita in cattività all’interno della serra. A causa del suo comportamento nelle precedenti fasi l’essenza Brassica napus è stata eliminata dalla terza fase. In questa fase i semi delle essenze Helianthus annus e Glycine max sono stati fatti germinare in laboratorio in condizioni controllate, utilizzando diversi tipi di terreni e diverse percentuali di percolato in acqua di rete, allo scopo di testare la massima percentuale di percolato da usare per l’irrigazione. I semi di Glycine max hanno presentato una migliore germinazione su sabbia irrigata con una percentuale di percolato in acqua pari al 5%, mentre i semi di Helianthus annus hanno germinato meglio sul terreno argilloso irrigato con una percentuale di percolato in acqua pari al 10 e al 20%. Si è quindi deciso di irrigare gli stessi vasi della seconda fase con una miscela contenente il 20% di percolato e l’80% di acqua grigia. La metà dei vasi è stata irrigata con acqua di rete ed usata come controllo. Nell’ultima fase sperimentale sono state usate le stesse vasche (otto) della prima fase, quattro per ogni essenza (Helianthus annus e Glycine max), all’interno della serra. Sei vasche sono state irrigate con una miscela di percolato (10-60%) e acqua di rete (90-40%), le altre due solo con acqua di rete ed usate come controllo. I risultati dell’intero lavoro si possono riassumere in termini di efficienza di rimozione di ogni parametro analitico misurato. Le analisi sono state effettuate in doppio ed è stato calcolato il bilancio di massa per i parametri più significativi (fosforo e azoto). Il fitotrattamento non ha inibito la crescita delle essenze, anzi le piante irrigate con acque di rifiuto, in tutte le fasi, possedevano più biomassa e un apparato radicale più lungo di quelle irrigate con acqua di rete. Le stesse considerazioni si possono fare per la produzione dei semi. La rimozione dei nutrienti dalle acque di rifiuto ad opera delle piante è stata molto buona fino alla fase di fioritura quando ha cominciato a decrescere. Nella prima fase è stato fondamentale per la crescita delle piante l’apporto di nutrienti dovuto all’introduzione di percentuali sempre maggiori di acque gialle (fino al 3.5%) all’acqua di rete, che di per sé ne è sprovvista. Per quanto riguarda l’irrigazione con miscele di percolato, la migliore efficienza di rimozione di azoto e fosforo in aggiunta ad una buona crescita delle piante, si è avuta con la miscela al 20%. La sabbia, tranne nel caso del Brassica napus, non si è rivelata un buon substrato di crescita nemmeno quando l’acqua di irrigazione era il percolato, ricco di nutrienti. I migliori risultati per quanto riguarda le velocità di rimozione dei nutrienti dall’acqua di irrigazione si sono ottenuti quando il substrato di crescita era il suolo misto

Linum usitatissimum (flax), Brassica napus var. oleifera (oilseed rape), Miscanthus x giganteus (miscanthus) and Urtica dioica (nettle) were investigated to assess their potential as phytoremediation crops. Germination experiments using flax and oilseed rape established that seedling germination was not inhibited by exposure to metals in solution except at the highest concentrations considered. Germination was, however, not a reliable indicator of plant metal tolerance as metal toxicity to emerged seedlings was evident in contaminated soil treatments exhibiting good germination rates. Four plant species were grown in soils containing six metals at both highly and marginally spiked levels, to reproduce genuine contaminated soils whilst allowing the study of each metal in isolation. A sewage sludge treated soil with a high metal and organic matter content was also included in the study. Miscanthus was the species most tolerant of the highly contaminated soils. The highest tissue concentrations recorded in plants exposed to the highly contaminated soils were (969 mg Zn/kg) in stems of miscanthus and (919 mg Cd/kg) in stems of nettle, but plant growth in these soils was generally poor. The plant species survived well in the sewage sludge soil, although metal uptake from this matrix was low. Oilseed rape and nettle accumulated the highest tissue metal concentrations in the study of marginally contaminated soils. Indeed the highest tissue concentration recorded for plants grown in all of the soils was found in nettle grown in the marginally contaminated Zn soils (1937 mg/g). Miscanthus, was able to remove a greater weight of metal from the soil owing to its higher biomass, despite having a lower tissue metal concentration than the other species. Flax, miscanthus, nettle and oilseed rape have been shown to have potential to act as part of a phytoremediation programme, however, more work with these crops is required before film advice can be given on commercial application of the crops in contaminated land remediation.

Thesis (M.S.)--University of Toledo, 2005.
Typescript. "A thesis [submitted] as partial fulfillment of the requirements of the Master of Science degree in Biology." Includes bibliographical references (leaves 54-61).

Thesis (M.S.)--University of Missouri--Rolla, 2007.
Vita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed November 16, 2007) Includes bibliographical references (p. 85-89).

Plant-based remediation techniques that can address mixtures of heavy metals and organic contaminants in soil warrant investigation due to their cost effectiveness and public acceptability. The potential of phytoremediation to remediate mixtures of heavy metals and hydrocarbons in soil is presented in two papers. A hydropic screening of twenty-seven forage grasses, grown in a solution containing 100 muM Zn, 5 muM Cu and 1 muM Cd, provided six species that were exceptionally metal tolerant. These six species were examined for their growth response and root phenolic secretion at five levels of hydroponic heavy metal contamination. Phenolic secretion, an indicator of a plant's capacity to promote polycyclic aromatic hydrocarbon (PAH) degradation, increased with heavy metal contamination, however, the values were low (<30 mug/g root). Two high biomass producing, metal-tolerant grasses, Bromus riparius and Arrhenatherum elatius, were combined with M2Rhizo4, a strain of plant growth-promoting rhizobacteria. The plant-bacterial combinations were established in artificial and genuine soils contaminated with heavy metals and PAHs at a range of concentrations. In contaminant-free artificial soil, inoculation promoted B. riparius growth by 25% compared to non-inoculated plants. In artificial soil, contaminated with 495 mg/kg Zn, 263 mg/kg Cu and 23 mg/kg Cd, M2Rhizo4 promoted B. riparius growth by 22%. In chromated-copper-arsenate (CCA) and creosote contaminated soil, M2Rhizo4 inoculated A. elatius had 15% more biomass and greater survival rates than non-inoculated A. elatius. A phytoremediation system composed of metal-tolerant plants inoculated with hydrocarbon-degrading or plant growth promoting bacteria may be suitable for sites contaminated with a mixtures of hydrocarbons and heavy metals.

Bioremediation of petroleum contamination has been used by the petroleum industry for decades. Phytoremediation is an emerging technology that is too new to be widely accepted. There are many unknowns in petroleum phytoremediation. This research focuses on furthering our understanding of the potential for phytoremediation of petroleum-contaminated soils & sludges. A series of experiments were conducted to achieve the goal. In addition, critical reviews on petroleum biodegradation, kinetics, volatilization, seed germination, soil microbial-pollutants-root relationship, the rhizosphere, and the plant root systems as well as recent research relating to petroleum bioremediation and phytoremediation are presented. Screening tests were conducted in cups and pots using 200 g of soil for 12 weeks. TPH (Total Petroleum Hydrocarbons) levels, seed germination, and plant biomass were measured. The results show that petroleum contaminants in soil have adverse effects on plant seed germination as well as plant growth. Soil freshly contaminated with diesel at 2% (w/w) level could totally hinder ryegrass and bromus grass seed germination. Oil sludge is found to be less toxic to both plant species. Ryegrass is found to be more tolerant to diesel and oil sludge soil than bromus grass. The possible contribution of volatilization loss to landfarming of diesel and oil sludge soils was investigated under conditions similar to those of other experiments of this study. The results show that oil sludge is non-volatile; although intense diesel flux volatilization from fresh liquid diesel is found within a short period of time (≤30 days), the actual diesel flux volatilization from diesel soils is far less than from liquid diesel. Germination of plant seeds in petroleum contaminated soils have been found to be a common difficulty for many researchers, especially when lighter molecular hydrocarbons exist in the soil. Germination experiments were conducted inside a 20°C incubator with 5.5cm Petri dishes containing 15 g soil sown with ryegrass seeds. Results show that ryegrass seed treatment in a 20% PEG (polyethylene glycol) solution and incubated at 20°C for three days increases the ryegrass seed germination rate from 20% to 90% in 3% (w/w) diesel soil (freshly contaminated). Similar effects were found for seeds sowed in oil sludge soils. Soil microcosms with 200 g soil in a 1.65 1 glass jar were conducted to investigate the biotreatability of diesel and oil sludge. The results indicate that both diesel and oil sludge compounds are biodegradable by indigenous soil microorganisms with various degradation rates. For example, TPH reduction and CO₂ evolution for 2% diesel soil continued for the whole test duration (189 days). For 3% oil sludge soil, TPH reduction slowed down and CO₂ evolution almost stopped after 50 days. A series of experiments were conducted in 40cm deep columns with 4.0kg soil. The columns were monitored for TPH levels, root development and CO₂ concentration over 102 days. The experimental design of the columns allows one to monitor soil CO₂ concentration directly, and is a design that hasn't been used in other research. The soil gas (CO₂) analysis shows that diesel soil columns planted with ryegrass had higher soil CO₂ concentration than un-planted ones, which implies that microbial activities are stimulated by the growth of rye grass roots. (A comparison of the results with data from the screening test show that higher rooting intensity (mg root/kg soil) in diesel soil results in better diesel degradation. The results indicate that living plant root growth and distribution in diesel-contaminated soil play an important role in the effectiveness of phytoremediation. Experiments were conducted outdoors with 4kg soil in plastic trays over 331 days to evaluate the feasibility of combining land treatment and phytoremediation. The results indicate that land treatment with or without phytoremediation achieved similar TPH removal. Since phytoremediation is likely to reduce the operation cost of a land treatment project, it could be economically feasible to link landfarming and phytoremediation as a treatment strategy. A rough estimate of the contribution of several mechanisms to the TPH loss in land treatment was done by comparing the data obtained from various experiments in this study. The contribution of biodegradation, volatilization, and un-extractable TPH loss are estimated to be: 38 to 48% biodegradation, 18% volatilization, and 19% un-extractable TPH loss for 2.0% diesel soil, and 33 to 34% biodegradation, negligible volatilization, and 7% un-extractable TPH loss for 3.0% oil sludge soil. This dissertation represents a systematic approach to investigate and develop the information and knowledge that would be useful in the application of phytoremediation for these petroleum-contaminated soils. Discussion and recommendations on further research are provided.

CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO
Nos últimos anos tem ocorrido um crescimento na extração e no beneficiamento de metais pesados ocasionando um aumento de rejeitos tóxicos na natureza, abrindo-se assim, a oportunidade para a pesquisa de técnicas de remediação de solos e águas, menos agressivas ao meio ambiente e com custos baixos. A fitorremediação é uma técnica de tratamento de solos, águas e sedimentos contaminados que promove o recapeamento de áreas devastadas e não altera o ecossistema, utilizando plantas como agentes remediadores. Entre as vantagens da fitorremediação, citam-se o custo reduzido e o baixo risco de dano ambiental ao solo, contrariamente a alguns processos de remediação física, química e da biorremediação. A técnica de fitorremediação consiste em se plantar e cultivar no local a ser tratado uma planta capaz de absorver o contaminante. O objetivo do trabalho foi estudar a capacidade de hiperacumulação de cádmio pela Ruppia maritima L., que é uma macrófita aquática enraizada e semi-cosmopolita encontrada em ambientes contaminados e possui uma capacidade adaptativa muito boa. A capacidade de fitorremediação da espécie, juntamente com a sua flora e fauna associadas, foi estudada utilizando-se soluções de cloreto de cádmio. A partir dos experimentos realizados concluímos que a Ruppia maritima possui uma capacidade muito boa de remediação de águas e sedimentos contaminados e de adaptação às condições adversas.
In the last years a growth has occurred in the extraction and refining of heavy metals causing an increase in the accumulation of wastes that are toxic to nature, thus opening up the opportunity for research in new soil and wastewaters remediation technics that are less aggressive to the environment and have lower costs. The established technics have not been developed with the preservation of the environment to be decontaminated in mind, nevertheless the current awareness in preserving the environmental balance acts as an incentive to the study of ecologically correct technologies. Phytoremediation is a technic for treatment of contaminated soil and wastewaters that promotes reforestation of devastated areas and does not modify the ecosystem, using plants as remediating agents. Amongst the cited advantages of phytoremediation are its low cost and risk of environmental damage to the soil, as opposed to certain physical and chemical remediation, and bioremediation processes. The phytoremediation technology consists of planting and cultivating on location a plant that is capable of absorbing the contaminating agent. The aim of this work was to study the cadmium hiperaccumulation capacity through the Ruppia maritima L., which is a cosmopolitan rooted aquatic macrophyte found in contaminated environments with a very good adaptation capacity. The phytoremediation capacity of this species, together with its associated flora and fauna, was tested using cadmium chloride solutions. From the developed experiments we concluded that the Ruppia maritima possesses a very good capacity for remediating contaminated soils and wastewaters and adapting to adverse conditions.

The use of natural remediation methods to remove contaminants from waste water is becoming more popular. Plants have been used for several decades, yet their use for municipal waste water contaminated by heavy metals is limited to a few studies which focus on the Mercury and Chromium (Bennicelli, et.al, 2004). This study specifically attempted to determine the viability for using Lemna minor to remediate municipally generated wastewater contaminated with copper. The study used 100 ml samples of wastewater, artificially spiked with 8 mg/L of copper sulfate and seeded with approximately 100 Lemna minor fronds. Each treatment was repeated 15 times and distilled water was added daily to maintain 100 ml samples. The addition of Lemna minor statistically lowered the copper concentration of the treatment groups (55% reduction in total Cu concentration). No significant decrease was seen in the control groups. While Lemna minor has metals accumulation potential, its wide spread use is limited by the toxic effect of copper on Lemna minor at relatively low levels.

The purpose of this paper was to combine available peer-reviewed literature on PCB phytoremediation and make direct comparisons using ANCOVA statistics in order to determine if and what plants are presently a viable option for the remediation of PCB contaminated soils. Pumpkin (Curbita pepo cv Howden) consistently had the top root and shoot concentrations, as well as total plant accumulation. Their consistency shows that they can be reliable in the field and the most viable option. Tall fescue and sedge were also top contenders. Due to the small sample size for many plants and accounting for several confounding variables, very few of plant species and groups showed to be significantly better at PCB accumulation. PCB phytoremediation can be used in conjunction with other technologies or as an early action plan to begin decreasing PCB concentration levels as well as contain the PCBs, thereby preventing any release.

The energetic compounds TNT (2,4,6-trinitrotoluene), RDX (hexahydro-1,3,5-trinitro-1,3,5-triazine), and HMX (octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine) contaminate military testing ranges worldwide yet are known to be degraded by plants and microbes in the laboratory. However, these contaminants remain persistent in the environment and represent a health threat to both humans and ecosystems. The use of traditional soil remediation technologies, such as landfilling or incineration, require large excavation costs and disrupt the ecology of the site. Phytoremediation, the use of green plants for the in situ treatment of contaminants, may be the most appropriate means of treating energetic residues present at military testing ranges. Eglin Air Force Base (EAFB), located near Niceville, FL, is one of the largest military installations in the world and holds many plant and animal species which are threatened or endangered. The use of explosives during training exercises on firing ranges at EAFB has resulted in contamination of energetics on range soils. In an effort to increase range sustainability with respect to explosives contamination, EAFB has been established as the site where phytoremediation processes will be explored for this research.

Phytoremediation is a relatively new technology that uses plants for the clean up of contaminated soils.Its low cost, simplicity and environmentally friendly approach make this technology a viable option for remediation but the main drawback is that it must be considered as long term alternative given its slow speed. This work is the first to report the use of Plant Growth Regulators(PGR)to enhance the performance of phytoremediation so that less time is needed for remediation.Soil samples were taken from a heavy metal contaminated, abandoned mine site for plant growth trials. A clean soil was also analysed and used for reference.Trials were carried out by growing corn in the contaminated soils and using various concentrations of IBA and NAA together with soil amedments to see if these could increase the accumulation of Zn, Mn, Cu, Bb and Fe in corn. Several further tests were conducted and results noted.
Doctor of Philosophy (PhD)

Thesis (Ph.D.) -- University of Western Sydney, Macarthur, 2001.
A thesis presented to the University of Western Sydney, in partial fulfillment of the requirements for the degree of Doctor of Philosophy, December, 2001. Bibliography : leaves 163-173.

Phytoremediation has been intensively studied during the past decade due to its cost-effectiveness and environmental harmonies. Most of the studies on treatment of heavy metal pollution in soil and water by plant species have been done in developed countries but are limited in Vietnam. In this study, we presented some research results of phytoremediation of polluted soils and water with heavy metals that were done by Institute of Environmental Technology for several last years. For treatment of heavy metal pollution in the water, some plants have great ability to accumulate heavy metals such as Vetiveria zizanioides, Phragmites australis, Eichhornia crassipes, Pistia stratiotes, Ipomoea aquatica, Nypa fruticans and Enhydra fluctuans. The heavy metal uptake into shoots and roots of 33 indigenous plant species in Thai Nguyen province was also determined. Two species of the plants investigated, Pteris vittata L. and Pityrogramma calomelanos L. were As hyperaccumulators, containing more than 0.1% As in their shoots while Eleusine indica, Cynodon dactylon, Cyperus rotundus and Equisetum ramosissimum accumulated very high Pb (0.15-0.65%) and Zn (0.22-1.56%) concentrations in their roots. Some experiments to clarify the potential of several plants as good candidates for phytoremediation of polluted soil by heavy metals were carried out in our institute
Phương pháp sử dụng thực vật để xử lý ô nhiễm đã được nghiên cứu nhiều trong thập kỷ qua do chi phí thấp và thân thiện với môi trường. Hầu hết các nghiên cứu về xử lý ô nhiễm kim loại nặng trong đất và nước bằng thực vật đã được thực hiện ở các nước phát triển nhưng ít có tại Việt Nam. Trong nghiên cứu này, chúng tôi giới thiệu một số kết quả dùng công nghệ thực vật để xử lý ô nhiễm kim loại nặng trong đất và nước tại Viện Công nghệ môi trường trong những năm gần đây. Dối với xử lý ô nhiễm kim loại nặng trong nước, một số thực vật có khả năng tích lũy tốt kim loại nặng như Vetiveria zizanioides, Phragmites australis, Eichhornia crassipes, Pistia stratiotes, Ipomoea aquatica, Nypa fruticans và Enhydra fluctuans. Sự hấp thụ và tích lũy kim loại nặng trong phần trên mặt đất và rễ của 33 loài thực vật bản địa tại Thái Nguyên cũng đã được xác định. Hai loài thực vật khảo sát là Pteris vittata và Pityrogramma calomelanos là những loài siêu tích lũy As, chứa hơn 0,1% As trong phần trên mặt đất của cây. leusine indica, Cynodon dactylon, Cyperus rotundus và Equisetum ramosissimum tích lũy Pb (0,15-0,65%) và Zn (0,22-1,56%) rất cao trong rễ. Một số thí nghiệm đánh giá tiềm năng của một số thực vật là đối tượng tốt cho xử lý ô nhiễm kim loại nặng trong đất đã được tiến hành trong phòng thí nghiệm của Viện Công nghệ môi trường

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

There is an ever-increasing need to address problems associated with the creation and disposal of wastes which result from human activities. Pb and Cd contamination is a common problem at many abandoned and uncontrolled commercial and industrial sites. Phytoremediation is one technology that can be employed to remove metals such as Pb from the soil. This study investigated the effectiveness of several plant and soil treatments on the uptake and retention of Pb and Cd by vegetation from contaminated soil at a Superfund site. Field plots were established and plant treatments included a mixture of grasses including Festuca, Poa. and Phleum; red clover (Trifolium Pratense); and sunflower (Helianthus annuus). Soil treatments included a common NPK fertilizer, ethylenediaminetetraacetic acid (EDTA), dilute sulfuric acid (H2SO4), and a mixture of EDTA and H2SO4 (EDTA+H2SO4). Trifolium tissue contained a greater quantity of Pb (182 mg Pb/kg tissue) than that of Poa (65 mg Pb/kg tissue). Cadmium concentration was similar in Poa and Trifolium tissue. ranging from 7.2 to 10.6 mg/kg tissue. Different soil treatments affected Pb levels found in plant tissue in order of effectiveness: H2SO4>EDTA>NPK>EDTA+H2SO4 The effects of soil treatments on Cd levels were similar to those for Pb with a difference of 0.1 mg Cd/kg tissue between EDTA and NPK treatments. Soil amendments differentially influenced Pb bioavailability and uptake, with H2SO4 exhibiting the greatest positive influence on Pb and Cd concentration in tissue. There was no correlation between the quantity of Pb and Cd up taken by vegetation at the site. The current study demonstrated the capability of common native plant species to grow on toxic and infertile soils, and the ability to uptake Pb and Cd to a limited degree. Regardless of tissue concentrations of Pb or Cd, Poa coverage at the site was generally dense. demonstrating the ability of Poa to become established on toxic soils and prevent soil erosion.
Department of Natural Resources and Environmental Management

Soils have been contaminated with cadmium (Cd) by the use of fertilizers, calcareous, pesticides and industrial and/or domestic effluents. It can be leached to groundwater, as well as be taken up by plants potentially leading to reduce growth and yield. It causes different damages to the cell, generating oxidative stress which is responsible for its toxicity, affecting all living organism. A balance in the redox state of the cell to maintain cellular integrity and metabolism is essential for organism tolerance. Thus, the antioxidant response of bacteria exposed to Cd was studied to understand the tolerance mechanism, and be able to develop a methodology to bioremediate contaminated soils. MDA and hydrogen peroxide contents and different enzymes activity of antioxidant system (SOD, CAT, GR and GST) of two strains from Burkholderia genus, one from a soil contaminated with Cd in high concentrations (strain SCMS54) and the other from soil without Cd (strain SNMS32) in two exposure time (5 and 12 h), were analyzed. Stress measurement (MDA and hydrogen peroxide content) and antioxidant enzyme activities (SOD, CAT, GR and GST) increased in almost all treatments in the presence of Cd. These results also indicate that strain SCMS54 (isolated from Cd contaminated soil) presents a higher metabolic diversity and plasticity due the expression of more isoforms of the enzymes SOD, CAT and GR. The strain also accumulates 50% more Cd. We also analyzed the response to Ni of these two strain, observing a similar response to Cd, except for GST enzyme expression, which in strain SCMS54 this enzyme was induced in the presence of Ni, indicating that this enzyme can be essential on Ni tolerance. After that, the strain isolated from Cd contaminated soil (SCMS54) was selected to proceed the studies to evaluate the benefits of tolerant microorganism-tomato plant interaction. The use of plants to remove heavy metals from contaminated soilhas less impact and a lower cost. Soil microorganisms can be able to solubilize or mobilize soil metals acting also as bioremediator. Besides the high tolerance to Cd, the strain SCMS54 can produce indole-acetic acid (IAA), solubilize inorganic phosphate and produce siderophore, revealing its potential in plantmicroorganism mutual and beneficial interaction. When interacting with tomato plants exposed to Cd, this bacterium led to decrease in plant peroxide concentration and chlorosis levels, promoted relative plant growth and reduced the root absorption of Cd resulting in an increase in plant tolerance to this highly toxic heavy metal. Indicating that inoculation of tomato plants with Burkholderia sp. SCMS54 promotes better growth when cultivated in the presence of Cd by a mechanism that appears to decrease Cd concentration in roots as a result of a bacterial-plant root beneficial interaction.
O cádmio (Cd) tem contaminado solos pelo uso de fertilizantes, calcário, agrotóxicos e resíduos industriais e/ou domésticos. Podendo ser lixiviado ao lençol freático ou absorvido pelas plantas,resultando na redução do crescimento e da produtividade. Esse metal afeta todos os organismos vivos e causa diferentes danos às células. A tolerância a esse metal se deve principalmente ao balanço do estado redox da célula para manter a integridade celular e metabolismo.Assim, foram isoladas bactérias de solo contaminado e não contaminado com Cd, selecionando isolados tolerantes a altas concentrações de diferentes metais (Cd, Ni e Zn), em seguida, foi observado a resposta do sistema antioxidante da bactéria na presença do Cd, a fim de auxiliar no desenvolvimento de metodologias para biorremediar solos contaminados. Foi quantificado MDA e peróxido de hidrogênio e a atividade de diferentes enzimas do sistema antioxidante (SOD, CAT, GR e GST) de duas estirpes do gênero Burkholderia tolerantes a todos os metais testados, uma isolada do solo contaminado com altas concentrações de Cd (estirpe SCMS54) e a outra do solo sem Cd (estirpe SNMS32) em dois tempos de exposição (5 e 12 h). Na estirpe SCMS54, as medidas de estresse (peroxidação lipídica e peróxido de hidrogênio) e a atividade das enzimas antioxidantes (SOD, CAT, GR e GST) da maioria dos tratamento com cádmio aumentaram, esta estirpe também expressa mais isoformas de SOD, CAT e GR, além de acumular 50% mais Cd. Esses resultados mostram que a estirpe SCMS54 (isolada do solo contaminado com Cd) apresenta uma maior diversidade metabólica e plasticidade. Foram analisadas também a resposta dessas duas estirpes ao Ni, observando uma resposta semelhante ao Cd, exceto na expressão da enzima GST, que no estirpe SCMS54 foi induzida na presença do Ni, indicando que essa enzima pode ser essencial na tolerância ao Ni. Portanto, a estirpe isoladado solo contaminado com Cd (SCMS54) foi selecionada para prosseguir os estudos e avaliar os benefícios da interação entre microrganismos tolerantes-plantas de tomate na fitorremediação. Essa técnica é usada remover para metais pesados do solo com um menor impacto e baixos custos. Os microrganismos do solo podem solubilizar e mobilizar metais do solo, atuando como biorremediador. Além da alta tolerância ao Cd, a estirpe SCMS54 produz ácido indol acético (AIA), solubiliza fosfato inorgânico e produz sideroforo, mostrando seu potencial na interação benéfica planta-microorganismo. Quando interagindo com as plantas de tomate expostas ao Cd, essa bactéria diminui a concentração de peróxido da planta e a clorose ocasionado pelo Cd,e reduz a absorção de Cd pela raiz resultando em um aumento da tolerância da planta ao metal pesado altamente tóxico. Assim, a inoculação de plantas de tomate com Burkholderia sp. SCMS54 promove crescimento da planta na presença de Cd, desencadeando um mecanismo que diminui a concentração de Cd nas raízes devido a essa interação benéfica bactéria-raiz da planta.

Phytoremediation has been intensively studied during the past decade due to its cost-effectiveness and environmental harmonies. Most of the studies on treatment of heavy metal pollution in soil and water by plant species have been done in developed countries but are limited in Vietnam. In this study, we presented some research results of phytoremediation of polluted soils and water with heavy metals that were done by Institute of Environmental Technology for several last years. For treatment of heavy metal pollution in the water, some plants have great ability to accumulate heavy metals such as Vetiveria zizanioides, Phragmites australis, Eichhornia crassipes, Pistia stratiotes, Ipomoea aquatica, Nypa fruticans and Enhydra fluctuans. The heavy metal uptake into shoots and roots of 33 indigenous plant species in Thai Nguyen province was also determined. Two species of the plants investigated, Pteris vittata L. and Pityrogramma calomelanos L. were As hyperaccumulators, containing more than 0.1% As in their shoots while Eleusine indica, Cynodon dactylon, Cyperus rotundus and Equisetum ramosissimum accumulated very high Pb (0.15-0.65%) and Zn (0.22-1.56%) concentrations in their roots. Some experiments to clarify the potential of several plants as good candidates for phytoremediation of polluted soil by heavy metals were carried out in our institute.
Phương pháp sử dụng thực vật để xử lý ô nhiễm đã được nghiên cứu nhiều trong thập kỷ qua do chi phí thấp và thân thiện với môi trường. Hầu hết các nghiên cứu về xử lý ô nhiễm kim loại nặng trong đất và nước bằng thực vật đã được thực hiện ở các nước phát triển nhưng ít có tại Việt Nam. Trong nghiên cứu này, chúng tôi giới thiệu một số kết quả dùng công nghệ thực vật để xử lý ô nhiễm kim loại nặng trong đất và nước tại Viện Công nghệ môi trường trong những năm gần đây. Dối với xử lý ô nhiễm kim loại nặng trong nước, một số thực vật có khả năng tích lũy tốt kim loại nặng như Vetiveria zizanioides, Phragmites australis, Eichhornia crassipes, Pistia stratiotes, Ipomoea aquatica, Nypa fruticans và Enhydra fluctuans. Sự hấp thụ và tích lũy kim loại nặng trong phần trên mặt đất và rễ của 33 loài thực vật bản địa tại Thái Nguyên cũng đã được xác định. Hai loài thực vật khảo sát là Pteris vittata và Pityrogramma calomelanos là những loài siêu tích lũy As, chứa hơn 0,1% As trong phần trên mặt đất của cây. leusine indica, Cynodon dactylon, Cyperus rotundus và Equisetum ramosissimum tích lũy Pb (0,15-0,65%) và Zn (0,22-1,56%) rất cao trong rễ. Một số thí nghiệm đánh giá tiềm năng của một số thực vật là đối tượng tốt cho xử lý ô nhiễm kim loại nặng trong đất đã được tiến hành trong phòng thí nghiệm của Viện Công nghệ môi trường.

Робота публікується згідно наказу ректора від 21.01.2020 р. №008/од "Про перевірку кваліфікаційних робіт на академічний плагіат у 2019-2020 навчальному році". Керівник проекту: доцент кафедри екології, к.б.н., Білик Тетяна Іванівна
Object of research – the use of plants in phytoremediation technologies to clean up soil from contamination Subject of research – determination of allelopathic activity of plants when used in phytoremediation. Aim of the work was to to evaluate the allelopathic effect between phytoremediants and native plants of phytocenosis in the development of phytoremediation soil cleaning. Methods - analysis of scientific literature, experimental studies of allelopathic effects of plants, statistical methods of processing results. Actuality. Phytoremediation is acknowledged as the perspective technology of soil decontamination and recovery. Nevertheless, there are certain factors that are supposed to influence this process, decreasing its effectiveness. The introduction of phytoremediation plants as the non-indigenous species into a phytocenosis of contaminated area may initiate the activation of an allelopathic activity of the present species. Allelopathic activity is commonly defined as a process of secretion of the secondary metabolites in a form of volatile compounds, exudates that inhibit development of other plants. Thus, this thesis focuses on the assessment of an allelopathic activity of the indigenous species and its influence on selected phytoremediation plants. Bioassay and germination test have been conducted to measure the effects of water-soluble extracts of Amaranthus retroflexus L., Cirsium arvense L., Barbarea vulgaris R. Br. And Artemisia absinthium L. on the introduced species used in phytoremediation.

Робота публікується згідно наказу ректора від 21.01.2020 р. №008/од "Про перевірку кваліфікаційних робіт на академічний плагіат у 2019-2020 навчальному році". Керівник проекту: доцент кафедри екології, к.б.н., Білик Тетяна Іванівна
Object of research – the use of plants in phytoremediation technologies to clean up soil from contamination Subject of research – determination of allelopathic activity of plants when used in phytoremediation. Aim of the work was to to evaluate the allelopathic effect between phytoremediants and native plants of phytocenosis in the development of phytoremediation soil cleaning. Methods - analysis of scientific literature, experimental studies of allelopathic effects of plants, statistical methods of processing results. Actuality. Phytoremediation is acknowledged as the perspective technology of soil decontamination and recovery. Nevertheless, there are certain factors that are supposed to influence this process, decreasing its effectiveness. The introduction of phytoremediation plants as the non-indigenous species into a phytocenosis of contaminated area may initiate the activation of an allelopathic activity of the present species. Allelopathic activity is commonly defined as a process of secretion of the secondary metabolites in a form of volatile compounds, exudates that inhibit development of other plants. Thus, this thesis focuses on the assessment of an allelopathic activity of the indigenous species and its influence on selected phytoremediation plants. Bioassay and germination test have been conducted to measure the effects of water-soluble extracts of Amaranthus retroflexus L., Cirsium arvense L., Barbarea vulgaris R. Br. And Artemisia absinthium L. on the introduced species used in phytoremediation.

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