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Increasing temperatures in alpine regions accompanied by glacial retreat is occurring rapidly due to climate change. This may affect riparian soils by increasing weathering rates, resulting in greater organic carbon (OC) release to rivers via movement of iron‐containing colloids and nanominerals. Increased concentrations of iron‐ or silcate‐nanominerals would result in higher surface area for OC adsorption. To test the influence of temperature on OC leaching, we examined mineral weathering and nanocolloid facilitated release of OC through a series of controlled laboratory batch and column experiments using sediment from the banks of the Nisqually River, Mount Rainier in Washington State (USA). Additional experiments were conducted using the same sediments, but with an illite amendment added to test the influence of additional surface area and nanominerals that many sediments along the Nisqually River contain. These higher‐ and lower‐surface‐area sediments (i.e., sediments with and without the illite amendment) were incubated for 90 d at 4 or 20 °C, followed by batch and column OC leaching tests. Results show that OC leaching rates for 20 °C were two to three times greater than for 4 °C. Further, our results suggest that nanocolloids are responsible for moving this increased OC load from these sediments. When hydrologically connected, OC is released from bank sediments to rivers faster than presently anticipated in fluvial environments experiencing climate change‐induced glacial retreat. Further, a one‐dimensional, finite‐element computational model developed for this study estimates that a 1 °C increase in temperature over a 90‐d summer runoff period increases the OC release rate from sediments by 79%.

Yttrium iron garnet is studied for the incorporation of cerium and thorium by a charge-coupled substitution with calcium for yttrium.

and hydroxides containing Mn(III) and Mn(IV) can oxidize organic ligands more rapidly than O2. Aromatic The complex interactions of oxidizable organic ligands with soil and nonaromatic ligands have been reported to dissolve Mn(III,IV) (hydr)oxide minerals have received little study by in situ spectroscopic techniques. We used a combination of an in situ electron reductively Mn(III,IV) (hydr)oxides (Stone and Morparamagnetic resonance stopped-flow (EPR-SF) spectroscopic tech- gan, 1984a,b) with the formation of polymeric reaction nique and stirred-batch studies to measure the reductive dissolution products that resemble soil humic substances (Shindo kinetics of birnessite (d-MnO2), a common Mn mineral in soils, by and Huang, 1982, 1984). Sorbed contaminants can be catechol (1,2-dihydroxybenzene). The reaction was rapid, indepen- released into solution following reductive dissolution of dent of pH, and essentially complete within seconds under conditions solid Mn(III,IV) (hydr)oxides by organic ligands and of excess catechol at pH 4 to 6. The overall empirical second-order reactive compounds may be sorbed or coprecipitated rate equation describing the reductive dissolution rate was d[Mn(II)]/ as a consequence of hydrolysis of the Mn(II) that is dt 5 k[CAT] 1.0 [SA] 1.0 where k 5 4( 60.5) (10 23 Lm 22 s 21 and [CAT] released (Xyla et al., 1992; Godtfredsen and Stone, 1994; and [SA] are the initial concentrations in molarity and meters square per liter. In the process, catechol was oxidized to the two-electron o- Larsen and Postma, 1997). Thus, redox cycling of Mn quinone product. The energy of activation (Ea) for the reaction was is dynamic and coupled to geochemical cycling of other

Cu-doped alumina-pillared montmorillonite clays are synthesized and characterized by ESR, XRD, and 27Al NMR.