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1	Understanding the sources and atmospheric processes of soluble iron in aerosols using a synergistic measurement approach Oakes, Michelle Manongdo 08 November 2011 (has links) This thesis focuses on the characterization of soluble iron in ambient/urban and source emission aerosols, primarily focusing on the sources and atmospheric processes contributing to iron solubility. Multiple techniques, including bulk and single particle measurements, were used to investigate the complex chemistry of iron solubility. A technique was developed and validated (PILS-LWCC), allowing for 12-minute measurements of water-soluble ferrous iron (WS_Fe(II)) in aerosols with a limit of detection of 4.6 ng m-3 and 12% relative uncertainty. The PILS-LWCC was deployed at several urban field sites (Atlanta, GA and Dearborn, MI) and a biomass burning event to determine major sources and atmospheric processes of WS_Fe(II) in aerosols. PILS-LWCC measurements suggest that industrial and biomass burning are sources of WS_Fe(II). In addition, acid-processing mechanisms also appeared to influence WS_Fe(II) concentrations, based on a strong correlation between WS_Fe(II) and SO42- (r2 = 0.76) as well as apparent aerosol acidity (r2 =0.78) during a field campaign in Atlanta, GA. Synchrotron-based techniques, such as X-ray Absorption Near-Edge Structure (XANES) spectroscopy and micro X-ray fluorescence measurements, were also used to identify the chemical composition (redox state and phase) and mixing state (two properties that may influence iron solubility) of source emission and ambient single iron-containing particles. These single particle measurements were used in conjunction with bulk iron solubility to assess the influence of chemical composition and mixing state on iron solubility. Single particle (synchrotron-based) and bulk iron solubility measurements suggested that iron solubility is not primarily driven by chemical composition in source emission and ambient particles. Differences in iron solubility, however, were related to single particle sulfur content in ambient and source emission aerosols, suggesting that similar sources/atmospheric processes control iron solubility in these samples. The relationship between iron solubility and sulfur content corresponded well with bulk ground-based measurements of ambient aerosol using the PILS-LWCC. Combined single particle and bulk online measurements provide compelling evidence that atmospheric acid processing, involving sulfur-containing acids (H2SO4), is an important formation route of soluble iron in ambient urban aerosols. The results of this thesis provide valuable information to further understanding the controls of iron solubility in atmospheric aerosols. Soluble iron Mineralogy Aerosols Synchrotron-based technology Online measurements Atmosphere Atmospheric aerosols Atmospheric chemistry
2	The seasonal cycling and physico-chemical speciation of iron on the Celtic and Hebridean shelf seas Birchill, Antony James January 2017 (has links) Shelf seas represent an important source of iron (Fe) to the open ocean. Additionally, shelf seas are highly productive environments which contribute to atmospheric carbon dioxide drawdown and support large fisheries. The work presented in this thesis describes the seasonal cycle of Fe in the Celtic and Hebridean Shelf Seas, and determines the physico-chemical speciation of Fe supplied from oxic margins. The results from repeated field surveys of the central Celtic Sea showed a nutrient type seasonal cycling of dissolved Fe (< 0.2 µm; dFe), which is surprising in a particle rich shelf system, suggesting a balance of scavenging and remineralisation processes. Coincident drawdown of dFe and nitrate (NO3-) was observed during the phytoplankton spring bloom. During the bloom, preferential drawdown of soluble Fe (< 0.02 µm; sFe) over colloidal Fe (0.02-0.2 µm; cFe) indicated greater bioavailability of the soluble fraction. Throughout summer stratification, it is known that NO3- is drawn down to < 0.02 µM in surface waters. This study revealed that both dFe and labile particulate Fe (LpFe) were also seasonally drawn down to < 0.2 nM. Consequently, it is hypothesised that the availability of Fe seasonally co-limits primary production in this region. At depth both dFe and NO3- concentrations increased from spring to autumn, indicating that remineralisation is an important process governing the seasonal cycling of dFe in the central Celtic Sea. In spring, summer and autumn, distinctive intermediate nepheloid layers (INL) were observed emanating from the Celtic Sea shelf slope. The INLs were associated with elevated concentrations of dFe (up to 3.25 ± 0.16 nM) and particulate Fe (up to 315 ± 1.8 nM) indicating that they are a persistent conduit for the supply of Fe to the open ocean. Typically > 15% of particulate Fe was labile and 60-90% of dFe was in the colloidal fraction. Despite being < 50 km from the 200 m isobath, the concentration of dFe was < 0.1 nM in surface waters at several stations. Broadly, the concentration of nutrients in surface waters described an oligotrophic environment where co-limitation between multiple nutrients, including Fe, appears likely. Over the Hebridean shelf break, residual surface NO3- concentrations (5.27 ± 0.79 µM) and very low concentrations of dFe (0.09 ± 0.04 nM) were observed during autumn, implying seasonal Fe limitation. The dFe:NO3- ratio observed is attributed to sub-optimal vertical supply of Fe relative to NO3- from sub-surface waters. In contrast to the shelf break, surface water in coastal regions contained elevated dFe concentrations (1.73 ± 1.16 nM) alongside low NO3-. Seasonal Fe limitation is known to occur in the Irminger and Iceland Basins; therefore, the Hebridean shelf break likely represents the eastern extent of sub-Arctic Atlantic seasonal Fe limitation, thus indicating that the associated weakening of the biological carbon pump exists over a wider region of the sub-Arctic Atlantic than previously recognised. These key findings demonstrate that the availability of Fe to phytoplankton may seasonally reach limiting levels in temperate shelf waters and that oxic margins persistently supply Fe dominated by colloidal and particulate fractions to the ocean.
3	Phosphordüngewirkung von Klärschlämmen aus Klärwerken mit Phosphateliminierung durch Eisensalze / Phosphate fertilization effects of sewage sludges from waste water processing plants with phosphate elimination by iron salts Abd El-Samie, Ihab Mohamed Farid 06 February 2003 (has links) No description available. 630 Landwirtschaft Veterinärmedizin Phosphatkonzentration Phosphateliminierung Phosphatsorption Phosphatausnutzung P-Entzug Mais Rotklee Weidelgras Gefäßversuche Klärschlamm Bodenlösung oxalatlösliches Eisen Eisensalze Phosphate concentration phosphate elimination phosphate sorption phosphate utilization phosphate uptake maize red clover rye grass pot experiments sewage sludge soil solution oxalate soluble iron iron salts 48.00 48.52 YEH 000: Düngung
4	Identifikation von Genen und Mikroorganismen, die an der dissimilatorischen Fe(III)-Reduktion beteiligt sind / Isolation of Genes and Microorganisms Involved in Dissimilatory Fe(III)-Reduction Özyurt, Baris 21 January 2009 (has links) No description available. 500 Naturwissenschaften allgemein Mathematics and Computer Science Metagenomik dissimilatorische Fe(III)-Reduktion Dissimilatory iron reduction DIR dissimilatory oxido-reduction of iron dissimilatory iron(III) reduction metal reduction ferricironreduction microbial iron respiration bacterial respiration microorganisms for energy production dissimilatory iron reducing bacteria dissimilatory metal reducing bacteria DMRB energy production electricity energy transduction microbial electricity electron donor electron acceptor electron transfer carbon source carbohydrate mannit mannitol biofilm mineral mineral formation microbial degradation ribosomal proteins cytochromes hypothetical proteins enzymes oxidation reduction ferric iron iron oxide Fe(II) Fe(III) soluble iron insoluble iron ferric reductase activity iron mineral formation mineralisation <i>E. coli</i> Escherichia coli environmental microorganisms life in extreme environments uncultivable bacteria soil microbial ecology anaerobic growth anaerobic incubation environmental sequences environmental DNA DNA extraction functional screening metagenomic metagenome meta-genome microbial ecology environmental genomics soil metagenome BACs sequencing bioinformatics microbial communities 16S rRNA phylogenetics 30 42.30 42.30 58.30 42.49 58.30 42.13 RA W

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