Quantifying sediment sources, pathways, and controls on fluvial transport dynamics on James Ross Island, Antarctica

Proglacial regions are enlarging across the Antarctic Peninsula as glaciers recede in a warming climate. However, despite the increasing importance of proglacial regions as sedi ment sources within cold environments, very few studies have considered fluvial sediment dynamics in polar settings and spatio-temporal variability in sediment delivery to the oceans has yet to be unravelled. In this study, we show how air temperature, precipitation, and ground conditions combine to control sediment loads in two catchments on James Ross Island, Antarctica. We estimate that the sediment load for the Bohemian Stream and Algal Stream over the 50 day study period, the average sediment load was 1.18 ± 0.63 t km⁻² d⁻¹ and 1.73 ± 1.02 t km⁻² d⁻¹ , respectively. Both catchments show some sensitivity to changes in precipitation and air temperature, but the Algal catchment also shows some sensitivity to active layer thaw. The downstream changes in sediment provenance are controlled by underlying lithology, while differences in sediment load peaks between the two catchments appear to be primarily due to differing glacier and snowfield coverage. This identification of the controls on sediment load in this sub-polar environment provides insight into how other fluvial systems across the Antarctic Peninsula could respond as glaciers recede in a warming climate

Depth-sensitive characterization of surface magnetic properties of as-quenched FeNbB ribbons

The longitudinal magneto-optical Kerr effect (MOKE) is used to study the surface magnetic properties of as-quenched FeNbB ribbons. MOKE surface hysteresis loops measured from both ribbon sides confirm different magnetic behavior. Wheel ribbon side shows heterogeneous (crystalline/amorphous) properties, thickness of crystalline phase (about 3 nm) was established by comparing the measured magneto-optical angles of Kerr rotation and ellipticity at different incident angles with the theoretical model. Effective crystalline phase observed at shiny ribbon side is harder (coercive field about 40 Oe) than that on wheel side and penetrates deeper into the material volume. Its thickness 1.3 m estimated from the weight reduction of the ribbon during surface etching is in good agreement with cross-section image obtained using the scanning electron microscopy (SEM). The sources of magnetoelastic anisotropy were identified in the bulk as well as on the ribbon surface using the magneto-optical Kerr microscopy