Interactions between natural organic matter, sulfur, arsenic and iron oxides in re-oxidation compounds within riparian wetlands: NanoSIMS and X-ray adsorption spectroscopy evidences

2015 ◽  
Vol 515-516 ◽  
pp. 118-128 ◽  
Author(s):  
Maya Al-Sid-Cheikh ◽  
Mathieu Pédrot ◽  
Aline Dia ◽  
Hélène Guenet ◽  
Delphine Vantelon ◽  
...  
Keyword(s):  
Organic Matter ◽  
Iron Oxides ◽  
Natural Organic Matter ◽  
Riparian Wetlands ◽  
X Ray

scholarly journals X-ray fluorescence mapping of mercury on suspended mineral particles and diatoms in a contaminated freshwater system

2014 ◽  
Vol 11 (18) ◽  
pp. 5259-5267 ◽  
Author(s):  
B. Gu ◽  
B. Mishra ◽  
C. Miller ◽  
W. Wang ◽  
B. Lai ◽  
...  
Keyword(s):  
Organic Matter ◽  
Iron Oxides ◽  
Natural Organic Matter ◽  
Spatial Localization ◽  
Suspended Particles ◽  
Aquatic Environments ◽  
X Ray ◽  
Mineral Particles ◽  
Geochemical Cycling ◽  
Freshwater System

Abstract. Mercury (Hg) bioavailability and geochemical cycling is affected by its partitioning between the aqueous and particulate phases. We applied a synchrotron-based X-ray fluorescence (XRF) microprobe to visualize and quantify directly the spatial localization of Hg and its correlations with other elements of interest on suspended particles from a Hg-contaminated freshwater system. Up to 175 μg g−1 Hg is found on suspended particles, but less than 0.01% is in the form of methylmercury. Mercury is heterogeneously distributed among phytoplankton (e.g., diatoms) and mineral particles that are rich in iron oxides and natural organic matter (NOM). The diatom-bound Hg is mostly found on outer surfaces of the cells, suggesting passive sorption of Hg on diatoms. Our results indicate that localized sorption of Hg onto suspended particles, including diatoms and NOM-coated oxide minerals, may play an important role in affecting the partitioning, reactivity, and biogeochemical cycling of Hg in natural aquatic environments.

Enrichment of chalcophile elements in seawater accompanying the end-Cretaceous impact event

2020 ◽  
Vol 132 (9-10) ◽  
pp. 2055-2066
Author(s):  
Teruyuki Maruoka ◽  
Yoshiro Nishio ◽  
Tetsu Kogiso ◽  
Katsuhiko Suzuki ◽  
Takahito Osawa ◽  
...  
Keyword(s):  
Organic Matter ◽  
Iron Oxides ◽  
Sedimentary Rocks ◽  
Reductive Dissolution ◽  
X Ray ◽  
Asteroid Impact ◽  
Chalcophile Elements ◽  
The Difference ◽  
Impact Heating ◽  
Fe Ions

Abstract Chalcophile elements are enriched in the Cretaceous–Paleogene (KPg) boundary clays from Stevns Klint, Denmark. As the concentrations of Cu, Ag, and Pb among several chalcophile elements such as Cu, Zn, Ga, As, Ag, and Pb are correlated with those of Ir, we suggest that these elements were supplied to the oceans by processes related to the end-Cretaceous asteroid impact. Synchrotron X-ray fluorescence images revealed that Cu and Ag exist as trace elements in pyrite grains or as 1–10-µm-sized discrete phases specifically enriched in Cu or Ag. The difference in carrier phases might depend on the materials that transported these elements to the seafloor. Based on their affinities with Cu, Ag, and Ir, iron oxides/hydroxides and organic matter were identified as the potential carrier phases that supplied these elements to the seafloor. Chalcophile elements adsorbed on iron oxides/hydroxides might have been released during reductive dissolution of iron oxides/hydroxides and incorporated into the pyrite produced simultaneously with the reductive dissolution of iron oxides/hydroxides. Both iron oxides/hydroxides and chalcophile elements were possibly released from the KPg target rocks (i.e., sedimentary rocks and/or basement crystalline rocks) by impact heating. Elements with a high affinity to organic matter would have been released upon its degradation and then converted into discrete minerals because of the deficiency in Fe ions. As such discrete minerals include the elements that form acid soluble sulfides such as Cu, Ag, and Pb, enrichment of these elements might have been induced by the intense acid rain just after the end-Cretaceous asteroid impact.

scholarly journals Chloramination of iopamidol- and bromide-spiked waters containing natural organic matter

2020 ◽  
Author(s):  
Nana Osei B. Ackerson ◽  
Hannah K. Liberatore ◽  
Susan D. Richardson ◽  
Michael J. Plewa ◽  
Thomas A. Ternes ◽  
...  
Keyword(s):  
Organic Matter ◽  
Natural Organic Matter ◽  
Disinfection Byproducts ◽  
Low Ph ◽  
Batch Reactors ◽  
X Ray ◽  
Organic Halogen ◽  
Low Concentrations ◽  
Total Organic Halogen ◽  
Organic Chlorine

Abstract Iopamidol (an iodinated x-ray contrast media) and bromide are precursors in the formation of halogenated disinfection byproducts (DBPs). The interactions of these precursors are vital to elucidate the formation of halogenated DBPs during chloramination. This work investigated the formation of total organic halogen and select individual DBPs in two laboratory-chloraminated source waters (SWs) containing iopamidol and bromide. Experiments were carried out in batch reactors containing Barberton SW (BSW) and Cleveland SW (CSW), spiked with iopamidol (5 μM), bromide (15 μM), and 100 μM monochloramine. Total organic iodine concentrations were approximately equal regardless of SW since they are mostly unreacted iopamidol and iopamidol DBPs. Almost equal amount of total organic chlorine (3–4 nM) was produced in the SWs but higher quantities of total organic bromine were formed in BSW than CSW. Substantial quantities of regulated trihalomethanes (THMs) and haloacetic acids (HAAs) were formed in the SWs, along with appreciable concentrations of iodinated trihalomethanes (CHBrClI, CHCl2I, and CHBr2I). Low concentrations of iodo-HAAs were detected, especially at low pH. Overall, bromide concentrations appeared to suppress iodo-DBP formation during chloramination of iopamidol in the presence of natural organic matter. A good correlation (R2 = 0.801) between the yields of regulated DBPs and iodo-DBPs was observed.

Impact of natural organic matter coatings on the microbial reduction of iron oxides

2018 ◽  
Vol 224 ◽  
pp. 223-248 ◽  
Author(s):  
Christine Poggenburg ◽  
Robert Mikutta ◽  
Axel Schippers ◽  
Reiner Dohrmann ◽  
Georg Guggenberger
Keyword(s):  
Organic Matter ◽  
Iron Oxides ◽  
Natural Organic Matter ◽  
Microbial Reduction ◽  
Reduction Of Iron

Bisulfide Reaction with Natural Organic Matter Enhances Arsenite Sorption: Insights from X-ray Absorption Spectroscopy

2012 ◽  
Vol 46 (21) ◽  
pp. 11788-11797 ◽  
Author(s):  
Martin Hoffmann ◽  
Christian Mikutta ◽  
Ruben Kretzschmar
Keyword(s):  
Organic Matter ◽  
Natural Organic Matter ◽  
Absorption Spectroscopy ◽  
X Ray ◽  
X Ray Absorption

scholarly journals Modelling metal–humic substances–surface systems: reasons for success, failure and possible routes for peace of mind

2012 ◽  
Vol 76 (7) ◽  
pp. 2643-2658 ◽  
Author(s):  
P. E. Reiller
Keyword(s):  
Organic Matter ◽  
Humic Substances ◽  
Iron Oxides ◽  
Metal Surface ◽  
Natural Organic Matter ◽  
Organic Material ◽  
Ternary Systems ◽  
Mineral Surfaces ◽  
Satisfactory Description ◽  
Wide Range

AbstractIron oxides and oxyhydroxides are commonly of considerable importance in the sorption of ions onto rocks, soils and sediments. They can be the controlling sorptive phases even if they are present in relatively small quantities. In common with other oxides and clay minerals, the sorption pH-edge of metals is directly linked to their hydrolysis: the higher the residual charge on the metal ion, the lower the pH-edge. Modelling of this process has been successfully carried out using different microscopic or macroscopic definitions of the interface (e.g. surface complexation or ion exchange models that may or may not include mineralogical descriptions). The influence of organic material on the sorption of many metals is of significant. This organic material includes simple organic molecules and more complex exopolymeric substances (e.g. humic substances) produced by the decay of natural organic matter. Sorption of this organic material to mineral surfaces has been the subject of a large body of work. The various types of organic substances do not share the same affinities for mineral surfaces in general, and for iron oxides and oxyhydroxides in particular. In those cases in which successful models of the component binary systems (i.e. metal–surface, metal–organic, organic–surface) have been developed, the formation of mixed surface complexes, the evolution of the surface itself, the addition order in laboratory systems, and the evolution of natural organic matter fractions during sorption, have often precluded a satisfactory description of metal–surface–organic ternary systems over a sufficiently wide range of parameter values (i.e. pH, ionic strength, concentration of humic substances). This manuscript describes the reasons for some successes and failures in the modelling of the ternary systems. Promising recent advances and possible methods of providing more complete descriptions of these intricate systems are also discussed.

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