• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 210
  • 154
  • 26
  • 18
  • 8
  • 8
  • 8
  • 8
  • 8
  • 8
  • 3
  • 3
  • 1
  • 1
  • Tagged with
  • 581
  • 581
  • 150
  • 148
  • 139
  • 95
  • 86
  • 77
  • 55
  • 52
  • 40
  • 39
  • 36
  • 36
  • 31
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
221

Toxicologically important DDT metabolites : Synthesis, enantioselective analysis and kinetics

Cantillana, Tatiana January 2009 (has links)
DDT was extensively and globally used as a pesticide in agriculture and for malaria vector control from the 1940’s until the 1970’s. Due to its heavy use, DDT became ubiquitously distributed throughout the environment. DDT and several DDT metabolites are persistent organic pollutants. Two DDT metabolites, 3-MeSO2-DDE and o,p’-DDD have been proved to be tissue specific toxicants in the adrenal cortex. They are bioactivated to reactive intermediates which bind covalently to the adrenal cortex causing cell death. Due to its tissue specific toxicity o,p’-DDD has been used as a chemotherapy drug for adrenal cancer in humans. The efficacy and potency is however low and o,p’-DDD treatment is associated with serious side effects. 3-MeSO2-DDE has been suggested as a potential alternative therapeutic agent. A key aim of this thesis has been to improve the understanding of the kinetics of the two adrenocorticolytic compounds o,p’-DDD, its two enantiomers and 3-MeSO2-DDE. To meet this objective chemical synthesis and enantioselective analysis were required. Furthermore, in vitro toxicity of o,p’-DDD enantiomers and diastereomers were performed. An 11 step synthesis of 3-SH-DDE has been developed to promote both labelled and unlabelled synthesis of 3-alkylsulfonyl-DDE. Toxicokinetic studies showed that 3-MeSO2-DDE and o,p’-DDD were accumulated in tissues and retained in adipose tissue in minipigs. 3-MeSO2-DDE however had a twice as long biological t1/2 and a considerably lower Vd compared to o,p’-DDD. Suckling offspring were more exposed to 3-MeSO2-DDE than their mothers who were given 3-MeSO2-DDE orally. Interindividual differences in enantiomer kinetics in minipigs were observed suggesting polymorphism among the minipigs. Preparative isolation of the o,p’-DDD enantiomers is presented allowing determination of the absolute structures of the o,p’-DDD enantiomers by X-ray. The pure enantiomer of o,p’-DDD showed significant differences in toxicity in human adrenocortical cells.
222

Determination of Antibiotics in the Swedish Environment with Emphasis on Sewage Treatment Plants

Lindberg, Richard January 2006 (has links)
Metoder har utvecklats för att kunna bestämma tolv antibiotikasubstanser, vanliga inom human medicin, i miljöprover. Fokus lades på trimetoprim samt substanser från följande grupper: fluorokinoloner, sulfonamider, penicilliner, cefalosporiner, nitroimidazoler, tetracykliner samt makrolider. Vid extraktion användes fast-fas extraktion för vattenprover och ultraljuds-assisterad fast-fas/vätske extraktion för fasta prover. För separering och bestämning användes vätskekromatografi tandemmasspektrometri. Interna standarder nyttjades för att öka noggrannhet och precision. Extraktionsutbyte låg mellan 50% och 100% för vattenfaser och 14% och 100% för fasta faser. Koncentrationer och massflöden bestämdes för antibiotikasubstanser i inkommande och utgående vatten och slam, från fem avloppreningsverk i Sverige, samt i avloppsvatten från ett sjukhus. I sjukhusavloppsvattnet så påträffades ciprofloxacin (en fluorokinolon) och metronidazol (en nitroimidazol) i höga halter (µg/L nivå). Screening-studien vid de fem avloppsreningsverken visade att norfloxacin, ofloxacin, ciprofloxacin och doxycyklin ofta förekom i inkommande och utgående vatten och slam. Trimetoprim och sulfametoxazol påvisades inte i slam men förekom i snarlika koncentrationer i det utgående vattnet relativt det inkommande. I vattenfasen så förekom de sex antibiotikasubstanserna i ng/L nivån och i slam förekom norfloxacin, ofloxacin, ciprofloxacin, och doxycyklin i låga mg/kg nivån. En studie genomfördes där beteendet hos antibiotikasubstanser under avloppsrening studerades. De två fluorokinolonerna, norfloxacin och ciprofloxacin, adsorberade till slam och mindre än 5% av den totala mängd som kommer till avloppsreningsverket påvisades i det utgående vattnet. I slam var motsvarande andel 70%. Resultat från en process som värmebehandlar rötat avvattnat slam antyder att cirka 50% av de två fluorokinolonerna bryts ner. Trimetoprim adsorberade inte till slam och 100% av total mängd återfanns i det utgående vattnet. Teoretiska beräkningar av koncentrationer och massflöden visade god korrelation till kvantitativa resultat. Ökad noggrannhet i beräkningarna fås genom att beakta stabilitet och fasfördelning. Effekten av antibiotikasubstanser i miljön är idag okänd. Resultat från testprotokoll där deras toxicitet bedöms är i många fall irrelevanta. Tester där organismer är kroniskt exponerade av biologiskt aktiva substanser vid låga koncentrationer är få. Dessutom så fokuserar de ej på de stora potentiella effekterna såsom utveckling eller bevaring av resistenta stammar av bakterier i miljön. Ytterligare studier av förekomst, öde och effekt av antibiotikasubstanser i miljön är nödvändiga. / Methods were developed for determining levels in environmental samples of twelve antibiotics that are commonly used in human medicine: trimethoprim and substances from the following groups: fluoroquinolones, sulfonamides, penicillins, cephalosporines, nitroimidazoles, tetracyclines and macrolides. These substances were extracted from liquid and solid samples by solid phase extraction and ultrasonic-assisted liquid/solid extraction, respectively. Liquid chromatography tandem mass spectrometry was then used to separate and quantify them, and internal standards were added to improve the accuracy and precision of the determinations. Extraction yields from aqueous and solid phases were in the ranges 50 - 100% and 14 - 100%, respectively. Concentrations and mass flows of antibiotic substances were determined in a hospital effluent and in the raw sewage water, final effluent, and sludge from five sewage treatment plants (STPs) scattered across Sweden. High levels (in the µg/L range) of ciprofloxacin (a fluoroquinolone) and metronidazole (a nitroimidazole), were found in the hospital effluent. The screening study of the five sewage treatment plants revealed that norfloxacin, ofloxacin, ciprofloxacin, and doxycycline were frequently present in the raw sewage water, final effluent and sludge. Trimethoprim and sulfamethoxazole were not detected in the sludge, but these substances were present in the final effluents at concentrations close to those of the raw sewage water. In the aqueous phase, these six antibiotics were present in the ng/L range and in the solid phase, norfloxacin, ofloxacin, ciprofloxacin, and doxycycline were present in the low mg/kg range. The behaviour of the antibiotic substances during sewage water treatment was also investigated in one of the STPs. The two fluoroquinolones, norfloxacin and ciprofloxacin, sorbed to sludge, and less than 5% of the total amounts that entered the STP were found in the final effluent. In sludge, the corresponding figure was 70%. Results from a process in which digested dewatered sludge was treated with heat (producing pellets) indicated that approximately 50% of the two fluoroquinolones had been degraded. Trimethoprim did not sorb to sludge and 100% of its total amount was found in the final effluent. Theoretical calculations of concentrations and mass flows correlated well with quantitative results for the antibiotics that were frequently detected, but not for the others. In order to increase the accuracy of the calculations, the stability and phase distribution of the antibiotics should be considered. The effects of antibiotics present in the environment are currently unknown. Results of test protocols to assess their toxicity are often irrelevant, and there have been few tests in which organisms have been chronically exposed to biologically active substances at low concentrations. In addition, these tests have not addressed the immense potential of antibiotics in the environment to induce the development of resistant strains of bacteria and to maintain populations of resistant strains. Further studies of the occurrence, fate, and, effects of antibiotic substances in the environment are required.
223

Deuterium isotopomers as a tool in environmental research

Betson, Tatiana January 2006 (has links)
This thesis describes the development and the use of quantitative deuterium Nuclear Magnetic Resonance spectroscopy (NMR) as a tool in two areas of environmental research: the study of long term climate-plant interactions and the source tracking of persistent organic pollutant. Long-term interactions between plants and climate will influence climate change during this century and beyond, but cannot be studied in manipulative experiments. We propose that long tree rings series can serve as records for tracking such interactions during past centuries. The abundance of the stable hydrogen isotope deuterium (D) is influenced by physical and biochemical isotope fractionations. Because the overlapping effects of these fractionations are not understood, studies of the D abundance of tree rings led to conflicting results. We hypothesized that both types of fractionations can be separated if the D abundance of individual C-H groups of metabolites can be measured, that is if individual D isotopomers are quantified. The first paper describes a technique for quantification of D isotopomers in tree-ring cellulose by NMR. The technique showed that the D isotopomers distribution (DID) was non-random. Therefore, the abundance of each isotopomer potentially contains individual information which suggests an explanation for the conflicting results obtained by measuring the overall D abundance (dD). In the second paper, this technique was used to study hydrogen isotope exchange during cellulose synthesis in tree rings. This revealed that some C-H positions exchange strongly with xylem water, while others do not. This means that the exchanging C-H positions should acquire the D abundance of source water, which is determined by physical fractionations, while non-exchanging C-H positions of tree-ring cellulose should retain biochemical fractionations from the leaf level. Therefore, the abundance of the corresponding D isotopomers should contain information about climate and physiology. When analysing tree-ring series, the DIDs should reflect information about temperature, transpiration and regulation of photosynthesis. In the third paper, we showed that CO2 concentration during photosynthesis determines a specific abundance ratio of D isotopomers. This dependence was found in metabolites of annual plants, and in tree-ring cellulose. This result shows that D isotopomers of tree-ring series may be used to detect long-term CO2 fertilisation effects. This information is essential to forecast adaptations of plants to increasing CO2 concentrations on time scales of centuries. In the fourth paper, the source of persistent organic pollutants in the environment was tracked using DID measurements. The dD values of two compounds of related structures were not enough to show indisputably that they did not originate from the same source. However, the DIDs of the common part between the two compounds proved that they did not originate from the same source. These results underline the superior discriminatory power of DIDs, compared to dD measurements. The versatility of DID measurements makes them a precious tool in addressing questions that can not be answered by dD measurements. / Betson, Tatiana R
224

Bis(4-chlorophenyl) sulfone and PCB methyl sulfone metabolites : Trends and chirality in the Baltic Sea environment

Norström, Karin January 2006 (has links)
The Baltic Sea was earlier identified as a highly polluted brackish water body and still is. The high concentrations of polychlorinated biphenyls (PCBs), p,p’-DDT and related compounds led to severe effects on several species in the Baltic region. However, the situation has improved significantly since the 1970’s resulting in lower exposures to a range of pollutants and healthier wildlife populations. Independent of this positive trend there are still new chemicals leaking into the Baltic Sea environment. The objective of this thesis is to improve the knowledge of sulfone containing compounds and pollutant metabolites in wildlife, with special interest in bis(4-chlorophenyl) sulfone (BCPS) distribution, temporal trend and exposure levels, and the methylsulfonyl-PCBs (MeSO2-PCBs). The latter are of particular interest for chiral MeSO2-PCBs. BCPS is used for the production of high temperature polymers and was detected as an environmental contaminant ten years ago. PCBs, p,p’-DDT and related compounds are still of scientific interest. BCPS is biomagnified and especially in the bird guillemot which has levels of up to 2000 ng BCPS/g fat compared to the grey seal with concentrations of about 60 ng/g fat. The seal levels are similar to the herring, the prey of the bird and seal, with concentrations of 30 ng BCPS/g fat. The guillemot concentration of BCPS has been similar over the last 30 years with a minimal, but significant, annual decline of 1.6%. The reason for the slow decline is not yet understood. Also MeSO2-PCBs and 3-MeSO2-DDE show a small decrease over time in guillemot egg (3 and 9%, respectively), which is less then for the parent compounds. This shows that the sulfone metabolites are more persistent than their precursors in the guillemot. Furthermore, all these sulfone containing compounds showed a specific retention to liver comparing different tissues in grey seal. The atropisomers of the chiral MeSO2-PCB were analysed in both the guillemot and the grey seal and showed to occur in a skewed relationship. This is particularly pronounced in seals where one atropisomer of each chiral congener is very dominating. The dominating atropisomers have been identified with an absolute R configuration, in both grey seal and guillemot. An enantioselective metabolism was indicated to occur when experimentally tested by CB-132 in rat. This thesis is stressing the high specificity in wildlife for one atropisomer in the pair of chiral PCB methyl sulfones being PCB metabolites, and the high BCPS concentrations in guillemot hatching in the Baltic proper.
225

Road traffic metals : sources and emissions

Hjortenkrans, David January 2008 (has links)
As the environmental regulations and technical progress have forced the factories’ old “end of pipe” solutions to improve, the metal emissions from point sources have decreased. Instead, the diffuse consumption emissions from goods in use now are in focus. The increased awareness of traffic as a major diffuse metal emission source emphasizes the need for more detailed information on the various traffic related sources. The main scope of this thesis is to study specific parts of metal emissions from some road traffic related sub sources such as brake lining and tyres. The metals in focus are antimony (Sb), cadmium (Cd), copper (Cu), chromium (Cr), lead (Pb), nickel(Ni) and zinc (Zn), and the research quantifies emissions from the different sub sources, trace changes over time as well as dispersal patterns and metal mobility in the roadside environment. The results show that even if the road traffic associated metal stocks are small compared to total in use stocks, their emissions are of major importance. The updated figures show that despite material developments during the last 10 years, tyres still are one of the main sources of Zn and Cd, while it can be excluded as a source of concern for the other metals studied. Brake linings are shown to be an especially pronounced source for Cu and Sb. The Pb and Cd emissions from brake linings and tyres have decreased as a result of decreasing material concentrations in these sources, most likely a result of EU regulations. Further the results reveals galvanized goods to be a major road traffic related source for Zn. The results show that the total metal concentrations in roadside soils have increased 3-16 times compared to regional background during the last decades. Each metal has a limited dispersal distance from the roads as well as down in the soil profile. Most metals are found within 10 m from the road in the uppermost 10 cm of the topsoil. However, the sequential extractions show that a large part of the metals found in the soil are rather easily mobilized and can be redistributed if the roadside soils become disturbed. Metals emitted due to decelerating activities are not correlated to elevated concentrations near road junctions. Instead the metals appear to be more evenly spread along the whole driven distance. The study points out Sb as an element that might be problematic to analyse. For Sb, which is sparsely studied as a roadside contaminant, there is a need of more general knowledge as it has a high accumulation rate in roadside soils. / I takt med ökade regleringar inom miljöområdet och en snabb teknikutveckling har fabrikerna allt mer spelat ut sin roll som emissionskällor till miljön. Istället har den diffusa emissionen som kommer från produktanvändning fått en större betydelse. En ökad medvetenhet om transporter och trafikens betydelse för samhällets konsumtionsemissioner understryker det ökade kunskapsbehovet för de trafikrelaterade emissionskällorna. Avhandlingens huvudsyfte är att studera specifika delar av metallemissionen från vissa trafikrelaterade källor så som bromsbelägg och däck. Metallerna som är i fokus är antimon (Sb), bly (Pb), kadmium (Cd), koppar (Cu), krom (Cr), nickel (Ni) och zink (Zn) och forskningen strävar efter att kvantifiera emissionerna från de olika källorna, spåra förändringar i emissioner över tid, kartlägga utsläppsmönster och metallrörlighet i vägnära jord. Resultaten pekar på att även om de trafikrelaterade källorna kvantitativt är små i jämförelse med de totala källorna så är deras emissioner av stor betydelse. De nya siffrorna visar att trots en materialutveckling inom området under det senaste årtiondet så är fortfarande däck en av de största källorna för Cd och Zn i stadsmiljö, medan de kan avfärdas som källa för de övriga studerade metallerna. Studien visar att bromsbelägg fortfarande är en viktig källa för Cu och Sb. Bly- och Cd-emissionerna från däck och bromsbelägg har däremot minskat drastiskt under samma period. Denna minskning beror troligen på en reglering på EU-nivå. Dessutom visar resultaten att galvaniserade ytor är den viktigaste källan till Zn i stadsmiljö. Metallkoncentrationerna i vägnära jord har ökat med 3 – 16 ggr jämfört med bakgrundshalterna i de undersökta områdena. Metallerna uppvisar endast en begränsad spridning från vägen och ner i jordprofilen. Den största metallpåverkan återfinns inom 10 m från vägen och i de översta 10 cm av jorden. Trots den begränsade spridningen så uppvisar de flesta metallerna en förhållandevis hög rörlighet, vilket innebär att de kan bli mobila vid störning av jorden. De bromsrelaterade metallerna uppvisar ingen korrelation till förhöjda halter nära korsningar utan är mer jämnt spridda över hela körsträckan. Studien pekar ut Sb som ett element som kan vara problematiskt att analysera på grund av dess flyktighet. Trots att Sb för närvarande har en snabb ackumulationstakt i trafikmiljö så är den endast sparsamt studerad. Mer generell kunskap om Sb är därför önskvärd.
226

Trends and exposure of naturally produced brominated substances in Baltic biota - with focus on OH-PBDEs, MeO-PBDEs and PBDDs

Löfstrand, Karin January 2011 (has links)
The semi-enclosed and brackish Baltic Sea has become heavily polluted by nutrients, anthropogenic organic and inorganic chemicals via human activities. Persistent organic pollutants (POPs) have been thoroughly investigated due to their linkage to toxic effects observed in Baltic biota. There has been far less focus on semi-persistent pollutants e.g. naturally produced oraganohalogen compounds (NOCs) and their disturbances in the environment. This thesis is aimed on assessment of levels and trends of naturally produced brominated compounds in Baltic biota; more specifically on hydroxylated polybrominated diphenyl ethers (OH-PBDEs), methoxylated PBDEs (MeO-PBDEs) and polybrominated dibenzo-p-dioxins (PBDDs). These, NOCs, may originate from production in algae and cyanobacteria. OH-PBDEs and MeO-PBDEs may also be formed as metabolites of polybrominated diphenyl ethers (PBDEs), i.e. well-known commercial flame retardants. High levels of OH-PBDEs, MeO-PBDEs and PBDDs are shown within Baltic biota (cyanobacteria, algae, mussels, fish), often in much higher concentrations than PBDEs which are possible anthropogenic precursors of OH- and MeO-PBDEs. The levels of OH-PBDEs, MeO-PBDEs and PBDDs are higher in the Baltic Sea than on the west coast of Sweden. Temporal and seasonal variations show fluctuations in concentrations of OH-PBDEs, MeO-PBDEs and PBDDs, possibly related with macroalgal life-cycles. OH-PBDEs, MeO-PBDEs and PBDDs are present in several filamentous macroalgae species, but considering the levels quantified, the time of peak exposure and the species life-cycle the macroalgae, Pilayella, Ceramium and Cladophora are suggested as major natural producers of OH-PBDEs and PBDDs. The high levels of OH-PBDEs, MeO-PBDEs and PBDDs in the Baltic Sea may affect numerous organisms in the ecosystem. The toxic effects of OH-PBDEs and PBDDs are of particular concern. This thesis stress the importance of assessing and monitoring these substances, since the exposure to OH-PBDEs and PBDDs, during summer, may cause acute effects in Baltic fish and wildlife. / At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: In press. Paper 4: Manuscript.
227

Undersökningsmetodik för klorerade lösningsmedel i marken / Chlorinated solvents in soil and groundwater : Investigation methodology and analysis of completed investigations

Walger, Ellen January 2006 (has links)
Chlorinated solvent are volatile organic substances that can be harmful for humans and for the environment. Examples of common chlorinated solvents are perchloroethene, PCE, and trichloroethene, TCE. Chlorinated solvents appear as contaminants in soils primarily where they have been used as washing fluids in dry-cleaning facilities or as degreasers in metal industries. Chlorinated solvents are DNAPLs (dense non-aqueous phase liquids), which means that they are not easily dissolved in water and that they sink to the bottom of the aquifer. Adsorption to soils is low so chlorinated solvents are mobile in soils. Chlorinated solvents can be harmful at low concentrations. Complete degradation can only occur under specific conditions. Because of the properties of these substances, investigation and analysis methodology are extra important for determining transport and risks in a contaminated area. In this work, investigation and analysis methods for chlorinated solvents are described. Planning, fieldwork, modeling and risk analysis are described. Projects concerning chlorinated solvents completed by Golder Associates AB have been compiled and analysed. Based on the compilation, conclusions have been drawn and statistics have been calculated. Investigations of the relation between concentrations in different media have been made as well as investigations of the relation between degradation products at different distances from the source and at different times after release. The data from the environmental investigations have been compared with theoretical literature values and modelling results. The results show that there is a large natural variation in the data and that the differences between different areas are quite large. The results confirm the theory that the percentage of degradation products increases with distance from the source and with time from release. In addition, solvents with a higher degree of chlorination seams to appear to a greater extent in the soil and the more volatile substances seams to appear to a greater extent in the soil air. / Klorerade lösningsmedel är flyktiga klorerade organiska ämnen som kan vara skadliga för människor och miljön. Exempel på vanliga klorerade lösningsmedel är perkloreten, PCE och trikloreten, TCE. Klorerade lösningsmedel förekommer som markföroreningar främst efter användning som tvättvätska i kemtvättar och som avfettningsmedel i metallindustrin. Klorerade lösningsmedel är DNAPLs (dense non-aqueous phase liquids), det innebär att de är svårlösliga i vatten och att de sjunker och lägger sig på botten av akviferen. Fastläggningen i jorden är liten hos klorerade lösningsmedel som därmed är rörliga i marken. De är farliga redan vid små koncentrationer och fullständig nedbrytning sker endast under vissa förutsättningar. Ämnenas egenskaper gör att undersöknings- och analysmetodiken är viktig för att riktigt kunna bestämma deras utbredning och risk på ett förorenat område. I detta arbete beskrivs undersöknings- och analysmetodiken för områden förorenade med klorerade lösningsmedel. Upplägg, fältarbete, modellering och riskbedömning beskrivs. Projekt som handlar om klorerade lösningsmedel utförda av Golder Associates AB har sammanställts. Sammanställningen har analyserats och utifrån den har olika slutsatser dragits och statistik beräknats. Bland annat har samband mellan halter i olika medier samt samband mellan halter av nedbrytningsprodukter på olika avstånd från källan respektive efter olika lång tid från läckage har undersökts. Data från miljöundersökningarna har även jämförts med teoretiska litteraturvärden samt modelleringsresultat. Resultatet visar att den naturliga spridningen av data är stor samt att resultaten skiljer sig åt mellan olika områden. Resultaten bekräftar teorierna att halten nedbrytningsprodukter ökar med avståndet från källan och med tiden samt att ämnen med högre kloreringsgrad finns i större utsträckning i jorden och att flyktigare ämnen finns i större utsträckning i porluften.
228

Long term heavy metal contamination from leakage water sediments

Brodd, Patrick January 2004 (has links)
No description available.
229

A laboratory study on the immobilisation of inorganic chlorine in soil

Thomsen, Frida January 2006 (has links)
Inorganic chlorine (Clinorg) is generally considered to be inert and has been used as a tracer for groundwater movements. This assumption is thereby fundamental for current knowledge about soil biogeochemistry. However, recent work showed that Clinorg can be retained, i.e. immobilised, in soil, which contradicts the previous assumptions. The aim of this laboratory study was to investigate if the processes that immobilise Clinorg in soil are affected by molecular oxygen (O2), and if the immobilisation occurs in the top soil layer only or also further down were the soil structure is different from the upper soil layer. Two experimental set-ups have been established. In the first experiment regarding the O2 regime (OXANIS), the immobilisation of Clinorg was studied in soil under oxic and anoxic conditions, respectively. In a second incubation study (SOLIS) the immobilisation was studied under oxic conditions in different layers of a coniferous forest soil. To investigate the immobilisation of Clinorg, a method using radiolabelled chloride 36 (36Clinorg) was applied. The use of radiolabelled chloride is an excellent and reliable method for studying transformation processes in soil systems. The results of the laboratory study showed that Clinorg retention rates under oxic conditions were much higher than retention rates under anoxic conditions, indicating an important role of O2. Furthermore, the immobilisation of Clinorg occurred in all soil layers were oxygen is provided, but rates were highest in the top soil layer (organic layer, O-horizon). Clearly, O2 influenced the net Clinorg retention, but additional studies are required to identify the processes behind this result. The calculated immobilisation rates for Clinorg in the three soil horizons correspond to the amount of organic material detected in the different soil horizons indicating a strong connection between the occurrence of organic matter in soil and the immobilisation of Clinorg.
230

Avena Sativa - En hyperackumulator? : En studie av havres kadmiumupptag / Avena Sativa - A Hyper Accumulator?

Eckert, Andreas, Fransson, Cecilia January 2009 (has links)
The aim of our research was to investigate if oat is capable of extracting cadmium to such extent that it is usable in decontaminating polluted soils. We grew oat in a hydroponic culture during 28 days in a controlled environment and a total of 30 plants were used. The nutrient solutions were contaminated with cadmium of ten different concentrations after seven days. After harvesting the plants, the roots were separated from the shoots, placed in separate containers and then turned to ashes. The cadmium content was measured three times per sample in an atomic absorption spectrometer. Our results indicate that the ability of oat to extract cadmium from a solution is linearly dependent of the cadmium concentration of the solution. We also noted that the resistivity to cadmium of oat is limited. When the concentration of accessible cadmium ions exceeded 0,06mM, a significant difference of the shoot growth appeared. The results we obtained from shoots and roots show cadmium amounts much higher in the roots than the shoots. Despite this difference there were sufficient amounts of cadmium in the shoots to call oat a hyper accumulator. This means that oat fulfills one of the criteria of a phytoextractor.

Page generated in 0.0801 seconds