<p>Chlorinated aliphatic hydrocarbons (CAH´s) were used widely within dry cleaning facilities and for metal degreasing until their toxicity was discovered. PCE is still used as dry cleaning liquid. Today CAH´s are found in soil environment at places where they have been used in the past. The CAH-concentration in trees growing on contaminated land has quite recently received attention as a cheap and effective way of assessing the extent of a CAH-contamination. The method has however, not been put into use in Sweden.</p><p>The aim of the study has been to investigate whether the CAH-concentration in tree cores could be used to delineate the spread of CAH in a soil environment under Swedish conditions in different seasons. The aim has also been to gain an understanding of the uptake process, as well as to identify the limitations of the method and important issues to consider when sampling.</p><p>Trees were sampled in March and June on Helgö 1:25, 1:26 in Växjö, Småland. Metal degreasing earlier conducted at this site has lead to the CAH contamination of soil and groundwater (PCE, TEC c-DACE). Mostly PCE, TCE, and chloroform were detected in tree cores. The CAH concentration was higher in June. Using the sum of PCE+TCE+c-DCE in trees to delineate the spread gave a result that was quite consistent with a delination done based on groundwater sampling.</p><p>The uptake of CAH by trees is governed by the uptake of water at the root. The water usage, together with the origin of the water used is important for the ability of the tree to take up CAH. The CAH concentration within trees is also dependent on the chemical properties of the compound (Log kow, solubility etc), the concentration of the compound in the soil as well as degradation processeses. The position and height of sampling in the trees, tree species as well as tree size are important factors to consider when sampling. Sampling during summer is preferred when the concentration of CAH in trees is likely to be higher.</p><p>The analysis of CAH in tree cores has potential to be used as a screening tool in soil investigations under Swedish conditions. It is a cheap and easy to use method, which would be a good complement to other investigative measures. However, an increased understanding of the processes involved, together with more analysis are needed., as this is a new method.</p> / <p>Klorerade lösningsmedel (CAH) användes i stor omfattning som bl a kemtvättmedel och avfettningsmedel tills dess att deras toxiska egenskaper blev kända. Perkloretylen (PCE) används än idag som kemtvättmedel. CAH återfinns ofta i markmiljö på de platser där de tidigare använts. Analys av CAH-koncentration i trädkärnor har uppmärksammats som en billig och effektiv metod för att översiktligt bedöma utbredningen av dessa föroreningar. Metoden har inte tidigare använts i Sverige.</p><p>Syftet med detta examensarbete är att undersöka om trädprovtagning kan användas för att bedöma utbredningen av föroreningar i markmiljö under svenska förhållanden vid olika årstider.</p><p>Analyserade CAH-halter i träd har jämförts med tidigare registrerade halter av CAH i grundvatten. Syftet har också varit att beskriva CAH-upptaget i träd, undersöka metodens begränsningar samt att sammanfatta viktiga aspekter vid provtagning.</p><p>Provtagningar av träd har genomförts under mars och juni på fastigheterna Helgö 1:25 och 1:26 i Växjö, där tidigare metallavfettning har medfört att mark och grundvattnet förorenats av CAH; perkloretylen (PCE), trikloretylen (TCE) och nedbrytningsprodukten dikloretylen (c1,2-DCE). Vid analys av trädkärnor detekterades främst PCE, TCE samt TCM (kloroform). Koncentrationen av CAH var högre i juni. Halten PCE+TCE+c-DCE i trädproverna gav en översiktlig bild av föroreningssituationen som överensstämde väl med de grundvattenprover som tidigare tagits på fastigheten.</p><p>CAH tas upp i vattenlöst fas vid trädens rötter. Trädets vattenbehov och vilket vatten det utnyttjar är därför viktigt för dess möjlighet att ta upp CAH. Ämnets kemiska egenskaper (log kow, flyktighet, mm.), samt förekomst och nedbrytning påverkar den halt som registreras i trädet. Vid provtagning bör provtagningspunkternas höjd över marken och position, trädart samt trädstorlek beaktas. Provtagning under sommaren är att föredra eftersom halterna då är högre.</p><p>Jämförelsen med grundvattenprovtagning visar att metoden har potential att användas i Sverige för att bedöma utbredningen av en CAH-förorening i markmiljö. Den är enkel att använda och kan vara ett alternativ på platser där konventionella metoder är svåra att genomföra. En ökad förståelse för involverade processer, samt utökade undersökningar av metoden är nödvändiga då metoden är ny.</p>

The main aim of this study was to test rehabilitation interventions in a system altered by heavy grazing, and to develop methods of monitoring these interventions.

La phytoextraction représente une solution environnementale prometteuse face au problème de contamination des sols en éléments traces (É.T). La présente étude s’intéresse aux différences intra et interspécifiques (S. purpurea, S. dasyclados, S. miyabeana) de trois cultivars de saule lorsqu’ils sont utilisés pour la phytoextration de six É.T. (As, Cd, Cu, Ni, Pb et Zn). Les objectifs sont (i) décrire les variations intrapécifiques du cultivar FISH CREEK (S. purpurea) lorsqu’il est utilisé pour la phytoextraction sur deux sites d’étude; et (ii) décrire les variations intra et interspécifiques des cultivars FISH CREEK (S. purpurea), SV1 (S. dasyclados) et SX67 (S. miyabeana) lorsqu’ils sont utilisés pour la phytoextraction d’un site d’étude. Les indicateurs de variations intra et interspécifiques sélectionnés sont les suivants : la biomasse totale, les concentrations en É.T. extraits et les facteurs de translocation (x ̅ pondérée des conc. É.T. dans les parties aériennes / conc. É.T. dans les racines). La contribution des propriétés du sol (degré de contamination, caractéristiques physicochimiques) à la phytoextraction a été évaluée. Les cultivars ont présenté des variations interspécifiques significatives. Cependant, les variations intraspécifiques sur un site d’étude étaient parfois plus importantes que celles mesurées entre les trois différents cultivars. L’amplitude des variations intraspécifiques que présentent le cultivar FISH CREEK sur deux sites d’étude est attribuée à l’influence du pH, de la minéralogie et au contenu en matière organique, lesquelles diffèrent entre les deux sites. Il a aussi été démontré que la phytoextraction des É.T. n’était pas systématiquement corrélée de façon positive avec le degré de contamination. Cela suggère que les concentrations en É.T. mesurées dans le sol ne peuvent pas expliquer à elles seules la variation des concentrations mesurées dans les tissus. L’implication des mécanismes de rétention dans le sol semblent être davantage responsable des variations observées. La compartimentation des É.T. suggère que le saule est efficace pour l’extraction du Cd et du Zn et qu’il est efficace pour la phytostabilisation de l’As, du Cu, du Ni, et du Pb. En ce qui concerne les quantités extraites, le cultivar FISH CREEK semble le plus performant dans la présente étude. / Phytoextraction is a promising solution to the environmental problem of soil contamination by trace elements (TE). This study focuses on intra and interspecific differences (S. purpurea, S. dasyclados, S. miyabeana) of three willow cultivars used for phytoextration of six TE (As, Cd, Cu, Ni, Pb and Zn). The objectives are (i) describe the interspecific variations of FISH CREEK cultivar (S. purpurea) used for phytoextraction on two study sites; and (ii) describe intra and interspecific variations of FISH CREEK (S. purpurea) SV1 (S. dasyclados) and SX67 (S. miyabeana) cultivars used for phytoextraction of a study site. The selected indicators of intra and interspecific variations are : total biomass, TE concentrations extracted and translocation factors (x ̅ weighted TE conc. in aerial parts / conc. TE in the roots). The contribution of soil properties (contamination level, physicochemical characteristics) to phytoextraction was evaluated. The cultivars showed significant interspecific variations. However, intraspecific variations were sometimes more important than variations measured between the three different cultivars grown on one study site. The magnitude of intraspecific variations of FISH CREEK cultivar grown on two study sites is attributed to the influence of pH, mineralogy and organic matter content, which differ between the two sites. It was also shown that the phytoextraction of TE was not consistently correlated positively with the contamination level. This suggests that the TE concentrations measured in soil can not by themselves explain the variation in the measured tissue concentrations. The involvement of retention mechanisms in soil appear to be more responsible for the observed variation. ET compartmentalization suggests that the willow is effective for Cd and Zn extraction and is effective for As, Cu, Ni, and Pb phytostabilisation. Regarding the amount extracted, cultivar FISH CREEK seems the most effective cultivar in this study.

Les HAP sont parmi les substances les plus problématiques parce qu'ils ont un fort pouvoir cancérigène, mutagène et ont, par conséquent, des effets nocifs pour la santé humaine. Parmi les techniques de remédiation des sols contaminés par des HAP, la phytoremédiation a été reconnue comme une méthode prometteuse en raison de ses avantages économiques et écologiques. Toutefois, en raison de la nature récalcitrante des HAP, et de facteurs environnementaux difficile à maîtriser, cette technique est encore limitée en termes d'efficacité, en particulier lorsqu'il s'agit de HAP de poids moléculaires élevés. L'inoculation des plantes avec des champignons mycorhiziens à arbuscules (MA), qui sont omniprésents dans la plupart des sols naturels et anthropiques, est connue pour favoriser l'élimination des HAP. Cependant, des résultats variables ont été rapportés quant à l'effet des plantes et des microorganisms associés notamment les champignons MA, sur la phytoremédiation des HAP et nécessite des études complémentaires. Des expériences été réalisées dans des cultures en pot et en microplaques, pour étudier l'influence de certains paramètres sur la dissipation des HAP dans la rhizosphère: l'espèce végétale, l'espèce fongique, la nutrition minérale, la nature des HAP, leur disponibilité et les interactions entre HAP. Quatre espèces de plantes (luzerne, fétuque élevée, ray-grass et céleri) et deux espèces de champignons MA (Glomus intraradices et Glomus mosseae) ont été testées dans un sol artificiellement contaminé avec trois HAP: le phénanthrène (PHE), le pyrène (PYR) et le dibenzo[a, h] anthracène (DBA). Le poids moléculaire des HAP est un facteur majeur influencant leur élimination. Lorsque le poids moléculaire des HAP était plus élevé, le nombre de bactéries dégradantes cultivables était plus faible, et l'efficacité de la phytoremédiation des HAP limitée. La présence de PHE a diminué la biomasse végétale et la colonisation mycorhizienne, mais il a augmenté la dissipation du DBA par co-métabolisme dans les expériences en pots et en microplaques. En revanche, cet effet n'a pas été observé entre le PYR et le DBA . La dissipation des HAP a varié avec les espèces de plantes et de champignons MA. Bien que les quatre espèces de plantes aient augmenté l'élimination du PHE, seule la luzerne a montré des effets positifs sur la phytoremédiation du DBA. Glomus intraradices a augmenté la biomasse végétale et l'absorption du phosphore par des plantes, et il a également augmenté la dissipation du DBA. Lorsque la co-culture de luzerne et fétuque était colonisée par Glomus mosseae, la biomasse obtenue était plus élevée, et la concentration des gènes de HAP-dioxygénase était significativement plus élevée qu'avec Glomus intraradices. Mais Glomus mosseae n'a montré aucun effet significatif sur la phytoremédiation du DBA. Ainsi cet effet des champignons MA sur la dissipation des HAP n'est pas seulement un effet biomasse. La concentration de phosphore et le régime d'alimentation en eau ont également influencé la colonisation mycorhizienne et la dissipation des HAP. Ainsi la dissipation du DBA en présence de plantes était significativement plus élevée que dans les témoins non plantés lorsque la teneur en eau était élevée et celle en phosphore plus faible, ce qui correspondait à la situation où le taux de mycorhization des plantes était le plus élevé. L'ensemble de ces résultats souligne la complexité des interactions entre plantes, microorganismes et polluants dans les sols. Ils montrent que tous les paramètres considérés affectent significativement la dissipation des HAP dans la rhizosphère des plantes, et méritent d'être pris en compte pour contrôler et améliorer la phytoremédiation / PAHs are among the most problematic substances as they could accumulate in the environment and threaten the development of living organisms because of their acute toxicity, mutagenicity or carcinogenity. Among remediation techniques for PAH contaminated sites, phytoremediation has been recognized as a promising method owing to its economical and ecological benefits. However, due to the recalcitrant nature of PAH, multivariate and changeful environment factors, this technique is still limited in terms of effectiveness, especially when dealing with high molecular weight PAHs. Inoculation of plants with arbuscular mycorrhizal (AM) fungi, which are ubiquitous in natural and most anthropogenically influenced soils, is known to benefit PAH phytoremediation. However, diverging results were reported on PAH dissipation in plant rhizosphere and the parameters affecting the AM fungi assisted PAH phytoremediation needed more investigation. Some of these parameters were considered in the present work: plant species, AM fungi species, phosphorus nutrition and watering regimes, PAH type, availability and interactions between PAHs. Experiments were performed in pot cultures and in microplates, with different plant species (including alfalfa, tall fescue, ryegrass and celery roots), two AM fungi (Glomus intraradices and Glomus mosseae) and three kinds of PAHs (phenanthrene (PHE), pyrene (PYR) and dibenzo[a,h]anthracene (DBA)), spiked to a soil. PAH molecular weight was a major parameter influencing PAH phytoremediation. With the increase of PAH molecular weight, the culturable PAH degraders decreased, so did the efficiency of phytoremediation. PHE decreased the plant biomass and AM fungi colonization, but it increased the DBA dissipation in both pot and microplate experiments. PYR did not increase DBA dissipation, and addition of PYR into PHE+DBA substrate decreased both PHE and DBA dissipation. PAH phytoremediation efficiency varied with the plant and AM fungi species. Although all four species of plants increased the disappearance of PHE, only alfalfa showed a positive effect on high molecular weight (HMW) PAHs. Glomus intraradices increased the plant biomass and phosphorus uptake of plants, and it also increased DBA dissipation in DBA or PHE+PYR+DBA spiked soil. Co-planted alfalfa and tall fescue colonized with Glomus mosseae obtained higher biomass and the concentration of the PAH-ring hydroxylating dioxygenase genes were significant higher, than with Glomus intraradices, but Glomus mosseae showed no or negative effect on DBA phytoremediation. The phosphorus concentration and water regime also influenced the AM fungus colonization and PAH dissipation. The highest AM colonization and a significant positive impact of mycorrhizal plants on the dissipation of DBA was detected in high-water and low-phosphorus treatment. Results indicated that complex interactions between plants, microorganisms and soil control the fate on PAHs. All the studied parameters significantly affected PAH dissipation in plant rhizosphere, and should be considered for controlling and improving phytoremediation efficiency

L’objectif principal de ce projet est d’évaluer le potentiel d’un système de marais filtrants combinés pour le traitement d’un lixiviat contaminé aux agents de préservations du bois - l’arséniate de cuivre chromaté (ACC) et le pentachlorophénol (PCP) - en portant une attention particulière au rôle des plantes. Pour ce faire, une expérience en pot faisant varier la concentration d’exposition de quatre espèces de macrophyte (Typha angustifolia, Phalaris arundinacea, Phragmites australis americanus et Phragmites australis australis) a été effectuée. Le suivi de quatre marais filtrants à écoulement horizontal sous-surfacique, plantés d’une des quatre espèces de macrophyte et d’un bassin planté de saules (Salix Miyabeana SX67) a également été réalisé. La résistance des plantes au milieu contaminé, la capacité de bioaccumulation des macrophytes et les efficacités de traitement des différents systèmes ont été analysés. Nos résultats montrent que la concentration d’exposition n’influence pas la capacité des plantes à croître en milieu contaminé. Par contre, il existe une relation dose-réponse entre la concentration d’exposition et la capacité de bioaccumulation des macrophytes. Les quatre marais pilotes ont tous des efficacités de traitements supérieures à 55% en 2013 et 82% en 2014 pour les contaminants à l’étude. Le bassin de saule a la capacité théorique d’évapotranspirer jusqu’à 1200 L par jour. De plus, ses efficacités de traitements sont supérieures à 59% pour tous les composés à l’étude. L’utilisation de marais filtrants pour le traitement d’un lixiviat contaminé aux agents de préservations du bois est donc une alternative intéressante aux méthodes de traitement conventionnel. / The main objective of this project is to evaluate the capacity of a combined constructed wetland system to treat a leachate polluted with two wood preservatives-chromium copper arsenate (CCA) and pentachlorophenol (PCP)- according a particular importance to the role of plants. The effect of the exposure concentration on four macrophytes species (Typha angustifolia, Phalaris arundinacea, Phragmites australis americanus and Phragmites australis australis) was evaluated using a pot experiment. Four HSSF pilot constructed wetlands, planted with one of these plants species, were monitored. The role of an HSSF constructed wetland, planted with willow (Salix Miyabeana SX67), placed at the end of the treatment chain was also assessed. The plants growth and survival and their bioaccumulation capacity were measured, and the system treatment efficiencies were monitored. There was no effect of the concentration on plants growth but the higher exposure concentration resulted in a higher bioaccumulation in the roots of the four macrophytes. All four pilots CW showed treatment efficiencies superior to 55% in 2013 and to 82% in 2014 for the pollutants tested. The willows CW have the theorical capacity to evapotranspirate up to 1200 L of water. Its treatments efficiencies were over 59% for all the pollutants tested. A combined constructed wetland system is a good alternative to conventional methods to treat a leachate polluted with wood preservatives.

L'exploitation, puis l'abandon, des sites miniers, dans l'oriental marocain, a entraîné une importante pollution des zones avoisinantes, générée par la dispersion de déchets riches en Pb. Pour résoudre ce problème, des programmes de phytomanagement sont à développer. Cependant, la réalisation de ces projets se heurte à deux contraintes : une faible diversité des plantes métallophytes et une méconnaissance des mécanismes de la tolérance au Pb.Dans ce contexte, l'objectif de mon travail de thèse a été de sélectionner une ou des plantes susceptibles d'entrer dans un programme de phytoremédiation et d'identifier des gènes impliqués dans la tolérance au Pb. Dans un premier temps, l'analyse des sols et des résidus miniers a révélé une importante contamination polymétallique du site d'étude. Des prospections floristiques ont ensuite permis d'identifier une plante de la famille des brassicacées, Hirschfeldia incana, prédominante sur les sites miniers pollués et qui accumule le Pb. L'accumulation du Pb chez H. incana a été confirmée en conditions contrôlées et une stratégie « gène candidat » a montré l'implication dans la tolérance au Pb de deux gènes, l'un codant pour une métallothionéine MT2a et l'autre pour un transporteur membranaire HMA4. Enfin, la comparaison des transcriptomes d'H. incana et d'A. thaliana a abouti à l'édification d'une liste de gènes candidats susceptibles d'être impliqués dans la tolérance au Pb. L'analyse fonctionnelle de quatre de ces gènes, codant pour une ferritine, une métallothionéine, une protéine fixatrice du cuivre et une défensine, a précisé leur rôle dans la tolérance au Pb. / Exploited, and then abandoned, mining sites, in the oriental Morocco, have polluted the neighboring regions, by dispersion of mining wastes containing Pb. Facing this problem, it is necessary to develop phytomanagement programs. Nevertheless, these project realisations encountered two major constraints: weak metallophyte plant diversity and misunderstanding of Pb tolerance mechanisms. In this context, the objectif of my work was to select plants compatible with a phytoremediation program and to identify genes implicated in lead tolerance. Firstly, soil and mining waste analysis has revealed an important polymetallic pollution of the studied region. Then, floristic explorations had permitted to identify a plant of the brassicaceae family, Hirschfeldia incana, which is predominant on the polluted mining regions and accumulated Pb. Pb accumulation in H. incana was confirmed in controlled conditions and a candidate gene approach has shown the lead tolerance implication of two genes, one coding for a metallothionein (MT2A) and the other a membrane transporter (HMA4). Finally, the transcriptome comparison from H. incana and A. thaliana has generated a list of candidate genes putatively implicated in Pb tolerance. Functional analysis of four genes, coding a ferretin, a metallothionein, a copper binding protein and a defensin, has permitted to clarify their role in Pb tolerance.

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.

Depuis le début de l'industrialisation, de nombreux déchets contaminés en éléments métalliques et métalloïdes sont rejetés dans l'environnement sans aucune gestion. L’activité minière a généré des quantités colossales de déchets, fins et non consolidés, riches en EMM stockés sous forme de terrils ou entreposés dans des bassins de décantation puis laissés à l’abandon à l’air libre sans aucun aménagement ni protection. Ces déchets restent sur place exposés à une forte érosion éolienne et hydriques induisant une dissémination des particules contaminées dans les différents compartiments de l’environnement (sols/sédiments/eau/atmosphère). Dans un premier temps, l’étude du devenir des éléments métalliques et métalloïdes dans les sols contaminés relatif à l’activité minière ont mis en évidence la présence de risques environnementaux et sanitaires associés. Les résultats soulignent que (i) le comportement géochimique des trois éléments (cadmium, zinc et plomb) est différent, (ii) la spéciation de ces éléments change clairement entre les déchets miniers et les sols, (iii) le Pb plomb peut causer des effets néfastes sur la santé pour les enfants. Dans un second temps, deux techniques de réhabilitation des sites contaminés ont été appréhendées: i) dans le cadre de la refonctionnalisation des sols, la potentialité d’une phytostabilisation assistée par des amendements organique et inorganique de parcelles contaminées avec le sapin de Douglas, ainsi que ii) la valorisation ex-situ par attaque des déchets miniers par voie alcaline qui mets en jeu la réduction de la source de pollution. / Since the beginning of industrialization, many wastes contaminated with metal(loid)shave been released into the environment without any management. Mining has generated huge quantities of fine, unconsolidated waste, rich in metal(loid)s, stored in tailing or in settling ponds and then left to be abandoned in the open air without any development or protection. This waste remains on site exposed to strong wind and water erosion leading to the spread of contaminated particles in the various environmental compartments (soil/sediment/water/atmosphere). First, the study of the fate of metal(loid)s in contaminated soils related to mining activity revealed the presence of associated environmental and health risks. The results highlight that (i) the geochemical behaviour of the three elements (cadmium, zinc and lead) is different, (ii) the speciation of these elements clearly changes between tailings and soils, (iii) Pb lead can cause adverse health effects for children. In a second step, two techniques for the rehabilitation of contaminated sites were apprehended: (i) in the context of soil refunctionalization, the potential for phytostabilization assisted by organic and inorganic amendments of plots contaminated with Douglas fir, as well as (ii) ex-situ recovery by attacking mining waste by alkaline way, which involves reducing the pollution source.

O avanço industrial e urbano associado ao aumento da produção dos bens de consumo resultou na geração de resíduos que, por muito tempo, foram descartados indiscriminadamente no ambiente, provocando danos quase sempre irreversíveis e de difícil recuperação. Dois experimentos foram conduzidos em solos contaminados por metais pesados, o primeiro devido ao descarte de produtos inorgânicos contendo grande carga de poluentes no solo; no segundo estudo a contaminação deve-se ao uso sucessivo de fungicidas contendo cobre em pomares cítricos do sul da Flórida. O primeiro estudo objetivou avaliar o uso de amenizantes orgânicos como mitigadores da toxicidade de bário, boro, cádmio, chumbo, cobre, níquel e zinco presentes no solo contaminado decorrente da adição de resíduo de sucata automobilística e avaliar o potencial fitoextrator do pinhão-manso (Jatropha curcas L.). Observou-se que o fornecimento da matéria orgânica na forma de turfas não amenizou a contaminação por metais pesados (Ba, Cd, Cu, Ni, Pb,Zn) e B; tal efeito pode ter ocorrido devido ao elevado pH deste solo mantido pelas práticas constantes de calagem. Os elementos apresentaram maior disponibilidade no solo ao longo das avaliações, exceto o boro que não apresentou significância. As plantas apresentaram sintomas de fitotoxicidade causados pelo elevado teor de boro e metais pesados no solo. A maior parte dos elementos metálicos se acumulou nos colmos e o boro nas folhas do pinhão manso, ou seja, a planta foi eficiente em translocar tais elementos para a parte aérea, situação desejável em uma fitoextratora. Ao final do experimento, os teores de Ba, Cd, Cu, Ni, Pb e Zn estavam mais disponíveis às plantas. O que indica que a matéria orgânica presente nas turfas mineralizou e tornou mais disponível estes metais pesados às plantas ao longo das avaliações. Pelos índices de transferência, de translocação e de remoção o pinhão manso foi viável somente para fitoextração de boro da área contaminada; estes índices também apontaram que o pinhão manso apresentou potencial para acumular B, Ba e Cd. O segundo experimento foi desenvolvido em casa de vegetacão com um argissolo coletado em uma área que tem recebido sucessivas aplicações de fungicidas a base de cobre, o que tem promovido o acúmulo significativo deste elemento nos solos sob produção de citros. O objetivo foi avaliar o potencial de fitoextração de cobre pelas plantas chinesas Splendens elsholtzia e Argyi elsholtzia para remover o excesso de cobre em solos contaminados devido a aplicação sucessiva de fungicidas cúpricos em pomares cítricos do sul da Flórida. A produção de massa seca de folhas, colmos e raízes e a concentração de cobre nos tecidos da Splendens elsholtzia foram superiores ao da espécie Argyi elsholtzia, o que indica que a Splendens elsholtzia é mais tolerante aos elevados níveis de cobre no solo. Assim, esta espécie pode ser indicada para programas de fitoextração em solos contaminados com cobre; entretanto, o índice de translocação do cobre indicou que as duas espécies não foram eficientes em translocar o cobre da raíz para parte aérea. / The industrial and urban progress associated with increased production of consumer goods has resulted in the generation of waste, which, for a long time, was indiscriminately discarded in the environment, causing damage usually irreversible to recover. Two experiments were conducted in soils contaminated with heavy metals: the first aimed at the disposal of products containing high loads of inorganic pollutants in the soil and the second focused on contamination due to the successive uses of fungicides containing copper in citrus groves of South Florida. The first study aimed to evaluate the use of organic soothers as mitigators of toxicity caused by barium, boron, cadmium, lead, copper, nickel and zinc in soil contaminated with waste resulting from the disposal of automobile scrap and to evaluate the phytoextraction potential of Jatropha (Jatropha curcas L.). It was observed that the supply of organic matter in the form of peat did not alleviate the contamination with heavy metals (Ba, Cd, Cu, Ni, Pb, Zn) and B, which may be attributed to the high pH of the soil due to constant practices of liming. The items showed higher availability in the soil during the evaluations, except for boron which showed no significance. The plants showed symptoms of phytotoxicity caused by high levels of boron and heavy metals in the soil. Most metallic elements are accumulated in the stems and boron in the leaves of Jatropha curcas, thus, the plant was efficient in the translocation of these elements to the shoot, a situation is desirable in phytoextraction. At the end of the experiment, the concentrations of Ba, Cd, Cu, Ni, Pb and Zn were more available to plants. This indicates that the organic matter present in the peat mineralized and made these heavy metals more available to plants. Considering the transfer rates of translocation and removal, the Jatropha was feasible only for phytoextraction of boron in the contaminated area, which shows that Jatropha has the potential to accumulate B, Ba and Cd. The second experiment was conducted in a greenhouse in an alfisol collected in an area that received repeated applications of copper-based fungicides, which promoted significant accumulation of this element in soils under citrus production. The objective was to evaluate the potential for phytoextraction of copper by the Chinese plants Splendens elsholtzia and Argyi elsholtzia to remove excess of copper in contaminated soils due to repeated application of copper-based fungicides in citrus groves of South Florida. The dry weight of leaves, stems and roots and the concentration of copper in the tissues of Splendens elsholtzia were higher than in Argyi elsholtzia, which indicates that the Splendens elsholtzia is more tolerant to high copper levels in the soil. Thus, this species may be indicated for phytoextraction of soils contaminated with copper; however, the rate of copper translocation indicated that the two species were not efficient to translocate copper from root to shoot.

O cádmio (Cd) é importante poluente ambiental, que prejudica a produtividade das plantas e traz consequências graves à saúde humana. Uma das possíveis estratégias para mitigar os danos provocados pelo Cd na planta é o suprimento adequado de potássio (K), uma vez que esse nutriente atua na modulação de processos fisiológicos e mecanismos antioxidantes dos vegetais. Objetivou-se avaliar a importância do K nos mecanismos envolvidos na tolerância do capim tanzânia (Panicum maximum cv. Tanzânia) ao estresse oxidativo induzido pelo Cd. As plantas foram cultivadas em casa de vegetação com delineamento de blocos completos ao acaso, em esquema fatorial 3x4, com três doses de K (0,4; 6,0 e 11,6 mmol L-1) combinadas com quatro doses de Cd (0,0; 0,5; 1,0 e 1,5 mmol L-1) fornecidas em solução nutritiva, com seis repetições, sendo três destinadas à avaliação dos parâmetros produtivos e nutricionais e outras três aos parâmetros fisiológicos e metabólicos. Foram avaliados dois períodos de crescimento das plantas, sendo o primeiro corte aos 35 dias após o transplantio das mudas e o segundo aos 27 dias após o primeiro. No segundo crescimento não foi adicionado Cd na solução nutritiva. O aumento do fornecimento de K resultou em incremento na produção de massa seca da parte aérea do capim tanzânia exposto às doses de Cd até 1,0 mmol L-1, no segundo corte. O acúmulo de Cd na parte aérea do capim foi mais elevado em condições de alta disponibilidade de Cd (1,5 mmol L-1) e de K (11,6 mmol L-1). O aumento das doses de Cd resultou em mais baixas concentrações de cálcio, magnésio, enxofre e manganês e mais elevadas concentrações de K, cobre, ferro e zinco na parte aérea do capim, no segundo corte. O maior fornecimento de K proporcionou mais elevadas taxas de assimilação de CO2 e de transpiração, condutância estomática, eficiência quântica do fotossistema II e taxa de transporte de elétrons em plantas expostas a doses intermediárias de Cd (0,5 a 1,0 mmol L-1). As concentrações de malondialdeído (MDA), peróxido de hidrogênio (H2O2) e prolina na parte aérea das plantas foram mais altas em condições de altas disponibilidades de Cd. As mais altas doses de K para plantas submetidas ao estresse por Cd resultaram em mais baixas concentrações de MDA devido ao incremento proporcionado por esse nutriente na atividade das enzimas antioxidantes superóxido dismutase (SOD), catalase (CAT), guaiacol peroxidase (GPX), ascorbato peroxidase (APX) e glutationa redutase (GR), avaliadas no segundo corte. O K promoveu aumento das concentrações de espermidina e espermina em plantas sob toxidez por Cd. Portanto, o K ameniza os efeitos tóxicos induzidos pelo Cd no capim tanzânia, reduzindo o estresse oxidativo por meio do aumento da atividade das enzimas antioxidantes e da concentração de poliaminas, o que resulta em maior produção de massa seca da parte aérea e maior acúmulo de Cd, aumentando a capacidade de fitoextração de Cd pelo capim tanzânia. / Cadmium (Cd) is an important environmental pollutant, which damages plant productivity and has serious consequences for human health. One of the possible strategies to mitigate the damage caused by Cd in the plant is the supply of potassium (K), since this nutrient acts in the modulation of the physiological processes and antioxidant mechanisms of the plants. The aim of this study was to evaluate the importance of K in the mechanisms involved in the tolerance of tanzania guinea grass (Panicum maximum cv. Tanzania) to the oxidative stress induced by Cd. Plants were grown in a greenhouse, in randomized complete block design, using a 3x4 factorial, with three rates of K (0.4, 6.0 and 11.6 mmol L-1) combined with four rates of Cd (0.0, 0.5, 1.0 and 1.5 mmol L-1) provided in nutrient solution, with six replications, three for the evaluation of productive and nutritional parameters and three for physiological and metabolic parameters. Two plant growth periods were evaluated, with the first harvest done at 35 days after seedlings transplanting and the second at 27 days after the first. In the second growth, Cd was not added to the nutrient solution. High K supply increased dry matter yield of tanzania guinea grass receiving Cd rates up to 1.0 mmol L-1, at the second harvest. The accumulation of Cd in the shoots of the grass was high in the conditions of high availability of Cd (1.5 mmol L-1) and K (11.6 mmol L-1). The increase in Cd rates resulted in low concentrations of calcium, magnesium, sulfur and manganese and high concentrations of K, copper, iron and zinc in the shoots of the grass at the second harvest. High K supply provided high rates of CO2 assimilation, transpiration, stomatal conductance, quantum efficiency of photosystem II and rate of electron transport in plants grown in intermediate rates of Cd (0.5 to 1.0 mmol L-1). The concentrations of malondialdehyde (MDA), hydrogen peroxide (H2O2) and proline in the shoots were high in conditions of high availability of Cd. High rates of K in plants submitted to Cd stress resulted in low concentrations of MDA due to the activities superoxide dismutase (SOD), catalase (CAT), guaiacol peroxidase (GPX), ascorbate peroxidase (APX) and glutathione reductase (GR) determined in the second harvest. K resulted in high concentrations of spermidine and spermine in plants under the toxic effect of Cd. Therefore, K alleviates the toxic effects induced by Cd in tanzania guinea grass, reducing oxidative stress by increasing the activity of antioxidant enzymes and the concentration of polyamines, which results in high shoot dry mass production and high Cd accumulation, increasing the capacity of Cd phytoextraction by tanzania guinea grass.