scholarly journals Chromium isotope fractionation during reduction of Chromium(VI) by Iron(II/III)-bearing clay minerals

2021 ◽  
Vol 292 ◽  
pp. 235-253
Author(s):  
Claresta Joe-Wong ◽  
Karrie L. Weaver ◽  
Shaun T. Brown ◽  
Kate Maher
Keyword(s):  
Clay Minerals ◽  
Isotope Fractionation ◽  
Chromium Vi

Manganese(II)-Catalyzed and Clay-Minerals-Mediated Reduction of Chromium(VI) by Citrate

2013 ◽  
Vol 47 (23) ◽  
pp. 13629-13636 ◽  
Author(s):  
Binoy Sarkar ◽  
Ravi Naidu ◽  
Gummuluru SR Krishnamurti ◽  
Mallavarapu Megharaj
Keyword(s):  
Clay Minerals ◽  
Chromium Vi ◽  
Mediated Reduction

scholarly journals Sulfur isotope fractionation during heterogeneous oxidation of SO<sub>2</sub> on mineral dust

2012 ◽  
Vol 12 (11) ◽  
pp. 4867-4884 ◽  
Author(s):  
E. Harris ◽  
B. Sinha ◽  
S. Foley ◽  
J. N. Crowley ◽  
S. Borrmann ◽  
...  
Keyword(s):  
Relative Humidity ◽  
Clay Minerals ◽  
Aqueous Phase ◽  
Isotope Fractionation ◽  
Mineral Dust ◽  
Surface Oxidation ◽  
Sulfur Cycle ◽  
Fractionation Factor ◽  
Sulfate Production ◽  
Aqueous Oxidation

Abstract. Mineral dust is a major fraction of global atmospheric aerosol, and the oxidation of SO2 on mineral dust has implications for cloud formation, climate and the sulfur cycle. Stable sulfur isotopes can be used to understand the different oxidation processes occurring on mineral dust. This study presents measurements of the 34S/32S fractionation factor α34 for oxidation of SO2 on mineral dust surfaces and in the aqueous phase in mineral dust leachate. Sahara dust, which accounts for ~60% of global dust emissions and loading, was used for the experiments. The fractionation factor for aqueous oxidation in dust leachate is αleachate = 0.9917±0.0046, which is in agreement with previous measurements of aqueous SO2 oxidation by iron solutions. This fractionation factor is representative of a radical chain reaction oxidation pathway initiated by transition metal ions. Oxidation on the dust surface at subsaturated relative humidity (RH) had an overall fractionation factor of αhet = 1.0096±0.0036 and was found to be almost an order of magnitude faster when the dust was simultaneously exposed to ozone, light and RH of ~40%. However, the presence of ozone, light and humidity did not influence isotope fractionation during oxidation on dust surfaces at subsaturated relative humidity. All the investigated reactions showed mass-dependent fractionation of 33S relative to 34S. A positive matrix factorization model was used to investigate surface oxidation on the different components of dust. Ilmenite, rutile and iron oxide were found to be the most reactive components, accounting for 85% of sulfate production with a fractionation factor of α34 = 1.012±0.010. This overlaps within the analytical uncertainty with the fractionation of other major atmospheric oxidation pathways such as the oxidation of SO2 by H2O2 and O3 in the aqueous phase and OH in the gas phase. Clay minerals accounted for roughly 12% of the sulfate production, and oxidation on clay minerals resulted in a very distinct fractionation factor of α34 = 1.085±0.013. The fractionation factors measured in this study will be particularly useful in combination with field and modelling studies to understand the role of surface oxidation on clay minerals and aqueous oxidation by mineral dust and its leachate in global and regional sulfur cycles.

scholarly journals Experimental constraints on potassium isotope fractionation between potassium solutions and clay minerals

2021 ◽  
Author(s):  
Xinyang Chen ◽  
Brian Beard ◽  
Clark Johnson ◽  
Xin-Yuan Zheng
Keyword(s):  
Clay Minerals ◽  
Isotope Fractionation

scholarly journals Kinetics and Products of Chromium(VI) Reduction by Iron(II/III)-Bearing Clay Minerals

2017 ◽  
Vol 51 (17) ◽  
pp. 9817-9825 ◽  
Author(s):  
Claresta Joe-Wong ◽  
Gordon E. Brown ◽  
Kate Maher
Keyword(s):  
Clay Minerals ◽  
Chromium Vi

Oxygen isotope fractionation effects in soil water via interaction with cations (Mg, Ca, K, Na) adsorbed to phyllosilicate clay minerals

2014 ◽  
Vol 515 ◽  
pp. 1-9 ◽  
Author(s):  
Erik Oerter ◽  
Kari Finstad ◽  
Justin Schaefer ◽  
Gregory R. Goldsmith ◽  
Todd Dawson ◽  
...  
Keyword(s):  
Oxygen Isotope ◽  
Soil Water ◽  
Clay Minerals ◽  
Isotope Fractionation ◽  
Oxygen Isotope Fractionation
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