A time-dependent chemistry model is used to predict reactive oxygen species (ROS=H2O2+O2 ) and dissolved Fe (DFe) speciation in the surface ocean. A new feature of the model is inclusion of biological sources of superoxide. The model suggests that biochemistry mediated by phytoplankton cells is as important as photochemistry for the formation of ROS. Formation of stable organic Fe(III) complexe...

Ethylenediaminetetraacetic (EDTA), cyclohexane-1,2-diaminetetraacetic (CDTA) and diethylenetriaminepentaacetic (DTPA) acids were investigated and compared as complexing agents for the speciation of chromium(VI/III), vanadium(V/IV) and iron(III/II) ions by capillary electrophoresis. The chromium(III) was selectively chelated with DTPA in order to impart a negative charge and similar mobility to ...

Total concentrations and fractionation of Cu, Zn and Pb in seven operationally defined phases (exchangeable, carbonates, manganese oxides, organic complexes, amorphous iron oxides, crystalline iron oxides and residual) were determined in sediments colonised by the halophyte species Halimione portulacoides and Spartina maritima in a Tagus estuary salt marsh (Portugal). We aimed to determine whet...

The Canary Islands have become a model region for evolutionary studies. We obtained 1.8 Kbp of mtDNA sequence from all known island forms of the endemic lizard genus Gallotia and from its sister taxon Psammodromus in order to reanalyze phylogenetic relationships within the archipelago, estimate lineage divergence times, and reconstruct the colonization history of this group. Well-supported phyl...

Close monitoring of liver iron content is necessary to prevent iron overload in transfusion-dependent anemias. Liver biopsy remains the gold standard; however, MRI potentially offers a noninvasive alternative. Iron metabolism and storage is complicated and tissue/disease-specific. This report demonstrates that iron distribution may be more important than iron speciation with respect to MRI sign...

Superoxide, the one-electron reduced form of dioxygen, is produced in the extracellular milieu of aquatic microbes through a range of abiotic chemical processes and also by microbes themselves. Due to its ability to promote both oxidative and reductive reactions, superoxide may have a profound impact on the redox state of iron, potentially influencing iron solubility, complex speciation, and bi...

Micro-organisms require certain metallic elements for growth and function (Hughes & Poole, 1989). These include, for example, the bulk elements potassium and magnesium, and trace elements such as manganese, iron, copper, zinc and molybdenum. Essential metals are shown in Fig. 1, the Periodic Table. The need for these essential metals is, or should be, acknowledged in the composition of growth m...

A mouse model of human disease was recently described by Bemstein I1 I . Hypotransferrinaernic mice have 5O-fold decreased serum transfenin levels, hypochromic. riiicrocytic (iron deficient) anaemia but develop liver iron overload I1.21. These mice parallel for the rare human disease atrmsferrlnaemia 13.41 and may be a useful model for hiiman iron overload disorders. Great interest is currently...

Hydrothermal vent fluids are highly enriched in iron (Fe) compared to ambient seawater, and organic ligands may play a role in facilitating the transport of some hydrothermal Fe into the open ocean. This is important since Fe is a limiting micronutrient for primary production in large parts of the world’s surface ocean. We have investigated the concentration and speciation of Fe in several vent...

Application of synchrotron radiation for measurement of iron red-ox speciation in atmospherically processed aerosols B. J. Majestic, J. J. Schauer, and M. M. Shafer Environmental Chemistry and Technology Program, University of Wisconsin – Madison, 660 N. Park St, Madison, WI 53706, USA Received: 10 January 2007 – Accepted: 17 January 2007 – Published: 29 January 2007 Correspondence to: J. J. Sc...