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Acid sulfate soils covers an area area about 600 km-2 along the coast line of Northern Sweden. These soils originate from land uplift and oxidized sulfide soils. The oxidation process releases sulfur and Fe(III) and will lower the pH-value and mobilize metals that will cause toxic environments for water living organisms. Concerns of how higher occurrence of extreme weather conditions will affect the mobilization of metals has occurred. Understanding of the mobilizations of metals in different catchment conditions is therefore important knowledge for preparation of risk analyzes to protect ecosystems from toxic effects. The aim of this study is to compare accumulation of metals in sediments from marine and limnic environments to investigate how lakes effects the mobilization of metals in catchments consisting of acid sulfate soil. Answering the questions of accumulation differences between the catchments and how organic matter affects the mobilization and accumulation of metals. Sediment cores were collected in two different catchment areas, known to be affected by acid sulfate soils, in Västerbotten county. 22 different elements were analyzed by x-ray fluorescence spectroscopy and Loss-on-ignition (LOI) was used as a proxy for organic matter. The results indicate that draining of land areas, often due to agriculture and deforestation, increases mobilization and accumulation of metals correlated with both organic and lithogenic fractions to a large extent. However, elements such as S, Ni, Zn, Fe, Cu, Na, Mg, Al, Rb, Sr and Zr are derived from mobilization from acid sulfate soils where elements with high correlation with organic matter accumulates in limnic environment conditions.

<p>The aquatic plant <i>Ipomoea aquatica</i> is a popular vegetable in Southeast Asia, often cultivated in nutrient rich and polluted waters. The overall aim of this thesis was to estimate potential risks for human health and reduced plant growth due to accumulation and toxicity of total-Hg, methyl-Hg, Cd and Pb.</p><p>In plants from cultivations in Thailand, the concentrations of Cd and Pb in the shoots were well beneath recommended maximum values for human consumption, but at some sites the Hg concentrations were high. It was demonstrated that <i>I. aquatica</i> has the capacity to accumulate much higher Cd and Pb concentrations in the shoots than found in field-cultivations, before exhibiting toxic symptoms. The Hg concentrations, however, occasionally reached levels that are toxic for the plant. Up to11% of total-Hg was methyl-Hg, the most toxic Hg species, though at one site it was 50-100%. To study if methyl-Hg is formed in <i>I.</i> <i>aquatica</i>, plants were exposed to inorganic Hg through the roots. Of the Hg that reached the young, metabolically active parts of the shoots, a part was transformed to methyl-Hg. A major proportion of absorbed metals was retained in the roots, which had a high tolerance for high internal metal concentrations. </p><p>The nutrient level did influence accumulation and effects of Hg, Cd and Pb in<i> I. aquatica</i>. Low external nutrient levels resulted in increased metal accumulation in the shoots and in metal-induced toxic effects in the plant at low external metal levels. A generous supply of sulphur or nitrogen induced formation of thiol-rich peptides in <i>I. aquatica</i>, compounds that have a metal detoxifying effect in plants. </p><p>To conclude, the levels of Cd and Pb in field cultivated <i>I. aquatica</i> do not pose any apparent threat to human health or risk for reduced plant growth. The levels of Hg however, were high at some sites and could be a health threat, for children and foetuses in particular, and especially considering the presence of methyl-Hg. The use of fertilizers is favourable as it reduces the risk for increased metal concentrations in <i>I.</i> <i>aquatica</i> and for reduced crop yields. </p>

The aquatic plant Ipomoea aquatica is a popular vegetable in Southeast Asia, often cultivated in nutrient rich and polluted waters. The overall aim of this thesis was to estimate potential risks for human health and reduced plant growth due to accumulation and toxicity of total-Hg, methyl-Hg, Cd and Pb. In plants from cultivations in Thailand, the concentrations of Cd and Pb in the shoots were well beneath recommended maximum values for human consumption, but at some sites the Hg concentrations were high. It was demonstrated that I. aquatica has the capacity to accumulate much higher Cd and Pb concentrations in the shoots than found in field-cultivations, before exhibiting toxic symptoms. The Hg concentrations, however, occasionally reached levels that are toxic for the plant. Up to11% of total-Hg was methyl-Hg, the most toxic Hg species, though at one site it was 50-100%. To study if methyl-Hg is formed in I. aquatica, plants were exposed to inorganic Hg through the roots. Of the Hg that reached the young, metabolically active parts of the shoots, a part was transformed to methyl-Hg. A major proportion of absorbed metals was retained in the roots, which had a high tolerance for high internal metal concentrations. The nutrient level did influence accumulation and effects of Hg, Cd and Pb in I. aquatica. Low external nutrient levels resulted in increased metal accumulation in the shoots and in metal-induced toxic effects in the plant at low external metal levels. A generous supply of sulphur or nitrogen induced formation of thiol-rich peptides in I. aquatica, compounds that have a metal detoxifying effect in plants. To conclude, the levels of Cd and Pb in field cultivated I. aquatica do not pose any apparent threat to human health or risk for reduced plant growth. The levels of Hg however, were high at some sites and could be a health threat, for children and foetuses in particular, and especially considering the presence of methyl-Hg. The use of fertilizers is favourable as it reduces the risk for increased metal concentrations in I. aquatica and for reduced crop yields.

Une nouvelle espèce de micro-algue photosynthétique, Coccomyxa actinabiotis, a récemment été découverte au sein d'une installation nucléaire. Cette algue présente une forte résistance aux radiations ionisantes et accumule certains radionucléides. Le développement d'une biotechnologie de décontamination des effluents liquides des réacteurs nucléaires basée sur C. actinabiotis est étudié du fait de ces propriétés. Ce travail vise plus particulièrement à caractériser et comprendre les processus d'accumulation par l'algue de l'argent et du cobalt, qui sont les radionucléides émetteurs gamma majoritaires dans les effluents liquides des réacteurs du parc électronucléaire français. Cette étude a été menée par quatre approches complémentaires : (a) Les cinétiques et les équilibres d'accumulation de ces métaux ont été déterminés par analyses ICP-MS (b) La distribution intracellulaire des métaux a été cartographiée à l'échelle nanométrique par fluorescence X de rayonnement synchrotron et par microscopie électronique en transmission (c) La spéciation de l'argent et du cobalt accumulés par la micro-algue a été déterminée par spectroscopie d'absorption X et par diffraction de rayons X (d) L'impact biologique de ces métaux sur l'algue a été examiné, notamment par l'étude des perturbations physiologiques, métaboliques et protéomiques associées à leur présence.L'ensemble de ces résultats dévoile une partie des processus à l'œuvre lors de l'accumulation d'argent ou de cobalt par C. actinabiotis. / A new green micro-alga species, Coccomyxa actinabiotis, was recently discovered in a nuclear environment. This alga is highly resistant to ionizing radiation and accumulates some radionuclides. Thanks to its properties, the development of a biotechnology based on C. actinabiotis for the clean-up of nuclear liquid effluents is under consideration. Our work aims more specifically at describing and understanding the alga's silver and cobalt accumulation processes; these metals being the main gamma emitting radionuclides present in liquid effluents issuing from French nuclear facilities.This study was carried out using four complementary approaches: (a) Kinetics and equilibriums of silver and cobalt uptake were assessed by ICP-MS analysis; (b) The subcellular distribution of the metals was mapped at a nanometric scale using synchrotron X-ray fluorescence and transmission electron microscopy; (c) The speciation of silver and cobalt taken up by the alga was assessed by synchrotron X-ray absorption spectroscopy and X-ray diffraction; (d) The biological impact of these metals on the alga was investigated, in particular the physiological, metabolic and proteomic perturbations they induce.Altogether, these results unveiled some of the processes involved in silver and cobalt accumulation by C. actinabiotis.

The overall efficiency of plants to remediate soils contaminated by metals depends on their growth ability especially on soils with low-fertility. For twelve weeks, the ability of Psoralea pinnata to grow well and remove chromium and iron from artificially contaminated soil was tested. The concentrations of chromium and iron in two soils obtained from different sources namely, University of South Africa premises (US) and commercial potting soil (PS) were 80 ppm, 130ppm, 180ppm, 230ppm, 280ppm, 330ppm, 380pp, 430ppm and 480ppm. Psoralea pinnata was transplanted into the contaminated soils and the experiments were watered daily to maintain 70% moisture at field capacity in a greenhouse. Shoot height and root length of Psoralea pinnata before and after planting were measured. Other parameters that were measured were number of leaves, wet shoot and dry weights, and wet root and dry weights. The growth of Psoralea pinnata, after 12 weeks of experimentation was noticeably affected by the concentrations of chromium and iron in the soil. The percentage increases in shoot height of Psoralea pinnata in the PS Soil (C-PS, 48cm from initial shoot height of 12.6cm) treatments were generally higher than the increases in the US Soil (C-US, 45.2cm from initial shoot height of 12.8cm) treatments. Psoralea pinnata in the (US) treatments accumulated Fe (50.02 ppm) from the soil more than Cr (32.38ppm). In the (PS) treatments, Psoralea pinnata also accumulated more Fe (60.57 ppm) than Cr (38.34 ppm). In the experiments containing both Fe and Cr, the US treatments with 40 ppm each of Cr and Fe, chromium was initially mostly accumulated by Psoralea pinnata (68%). At higher concentrations (320 ppm) of the combined metals (Cr and Fe) treatment, more Fe (55%) was accumulated in Psoralea pinnata. This study however showed that Psoralea pinnata may not be an efficient phytoextraction plant for hyperaccumulation. / Environmental Sciences / M. Sc. (Environmental Management)

The overall efficiency of plants to remediate soils contaminated by metals depends on their growth ability especially on soils with low-fertility. For twelve weeks, the ability of Psoralea pinnata to grow well and remove chromium and iron from artificially contaminated soil was tested. The concentrations of chromium and iron in two soils obtained from different sources namely, University of South Africa premises (US) and commercial potting soil (PS) were 80 ppm, 130ppm, 180ppm, 230ppm, 280ppm, 330ppm, 380pp, 430ppm and 480ppm. Psoralea pinnata was transplanted into the contaminated soils and the experiments were watered daily to maintain 70% moisture at field capacity in a greenhouse. Shoot height and root length of Psoralea pinnata before and after planting were measured. Other parameters that were measured were number of leaves, wet shoot and dry weights, and wet root and dry weights. The growth of Psoralea pinnata, after 12 weeks of experimentation was noticeably affected by the concentrations of chromium and iron in the soil. The percentage increases in shoot height of Psoralea pinnata in the PS Soil (C-PS, 48cm from initial shoot height of 12.6cm) treatments were generally higher than the increases in the US Soil (C-US, 45.2cm from initial shoot height of 12.8cm) treatments. Psoralea pinnata in the (US) treatments accumulated Fe (50.02 ppm) from the soil more than Cr (32.38ppm). In the (PS) treatments, Psoralea pinnata also accumulated more Fe (60.57 ppm) than Cr (38.34 ppm). In the experiments containing both Fe and Cr, the US treatments with 40 ppm each of Cr and Fe, chromium was initially mostly accumulated by Psoralea pinnata (68%). At higher concentrations (320 ppm) of the combined metals (Cr and Fe) treatment, more Fe (55%) was accumulated in Psoralea pinnata. This study however showed that Psoralea pinnata may not be an efficient phytoextraction plant for hyperaccumulation. / Environmental Sciences / M. Sc. (Environmental Management)

The role of metal accumulation in the pathophysiology of neurodegenerative diseases has been a hot topic in recent years due to the possibility of its treatment by chelating agents. Although the mechanisms of neurodegeneration are well known, the role of metal accumulation is still unclear. The main limitation are unsatisfactory methods for in vivo metal imaging; the most widely used technique is magnetic resonance imaging (MRI). Our aim was to assess the possibility of using transcranial sonography (TCS) in differential diagnosis of neurodegenerative diseases and to further explore the underlying factors of echogenicity. In the first study, using TCS fusion with MRI, we focused on location verification of the commonly assessed structures (substantia nigra and nucleus lentiformis) and exclusion of possible focal structural changes affecting the echogenicity in WD and PD patients. Moreover, obtained MRI were used for semi-quantitative comparison with TCS images. Although TCS has been confirmed to be highly beneficial in differential diagnosis of Wilson's disease and it should be recommended as a screening method for extrapyramidal patients with atypical course of the disease, the direct relationship between TCS and metal deposits could not be proven. The obtained results from the ultrasound fusion...

Little is known regarding the impact excessive waterborne metals, like copper (Cu), have on tropical freshwater species. Zebrafish (Dania rerio) only recently became popular as a tool for environmental monitoring, due to their fully sequenced genome. Despite this, little was known regarding the ionoregulatory physiology of zebrafish. I first examined the impact softwater acclimation has on the ionoregulatory capacity of zebrafish, and identified a high degree of phenotypic plasticity associated with changes in both gene and protein expression, which highlighted the need for proper experimental design for studies involving pre-acclimation to softwater. I then examined the acute and chronic effects of waterborne Cu exposure under the influence of both softwater conditions and the addition of protective ions (Na+ & Ca2+) . On an acute timeframe, I found that Na+ provided a greater protective effect than Ca2+ in reducing Cu uptake, which was mimicked during chronic exposure, although the transcriptional effects were not as clear cut. I found that although Na+ and Ca2+ provided protective effects from Cu accumulation, there were still tissue specific and global changes at the transcript level, as determined by microarray analysis. Furthemore, this set of experiments identified the metal- and stress- induced transcriptional effects due to Cu exposure, which is key to identifying gene endpoints of chronic Cu exposure. A final experiment went further and looked at the effects of mixed metal contamination, examining chronic waterborne Cu exposure with interactive effects of elevated dietary Fe on gene expression and tissue metal accumulation. Not only did this experiment highlight that gene expression is not necessarily reflected in protein abundance/activity, but also demonstrated that high dietary Fe can significantly alter the transcriptional expression pattern of Cu transporters in the gill, liver, and gastrointestinal tract. This thesis has made significant steps in identifying viable gene endpoints of Cu toxicity. / Thesis / Doctor of Philosophy (PhD)

L'activitat humana és una de les majors causes d'elevades concentracions de nutrients i substàncies tòxiques en els ecosistemes fluvials. Entre la gran varietat de factors que alteren aquests ecosistemes, l'eutrofització i la contaminació per metalls pesants són dos dels principals problemes ambientals en països desenvolupats. Els biofilms fluvials (també anomenats comunitats perifítiques) representen una eina valuosa per avaluar els efectes dels contaminants (ex. nutrients i metalls) en els ecosistemes aquàtics. Aquest treball pretén investigar el destí i els efectes del Cu en els ecosistemes fluvials centrant-se en les comunitats perifítiques. Diferents metodologies han estat desenvolupades i/o adaptades per investigar específicament la dinàmica del Cu, la seva toxicitat i bioacumulació en comunitats perifítiques naturals, i la interacció entre l'eutrofització i la toxicitat del Cu en aquests ecosistemes. / Human activity is one of the major causes of elevated concentrations of nutrients and toxic substances in fluvial ecosystems. Among the many ecosystem stressors, eutrophication and metal pollution are two of the major environmental problems in many developed countries. Fluvial biofilms (periphyton communities) are a useful tool for monitoring the effects of pollutants (e.g. nutrients and metals) into aquatic ecosytems. The present study aims to investigate the fate and effects of Cu in fluvial ecosystems focusing on periphyton communities. Different methodologies have been developed and/or adapted to specifically investigate the dynamics of Cu, its toxicity and bioaccumulation on natural periphyton communities, and the interaction between eutrophication and Cu toxicity in these ecosystems.