The natural wood regime in rivers

International audienc

Cerium Oxide Materials for the Solar Thermochemical Decomposition of Carbon Dioxide

We have experimentally investigated the thermochemical decomposition of carbon dioxide using pure cerium oxide fibrous structures. Experiments were conducted on-sun with a solar furnace and include two reaction steps: the thermal reduction of CeOα to CeOβ between 1500°C and 1600°C, and the re-oxidation of CeOβ to produce carbon monoxide under flowing carbon dioxide at temperatures between 800°C and 1200°C. A ceria-based cycle offers some advantages over similar thermochemical cycles including the reduction of sintering and volatility issues during thermal reduction, a stable crystal structure over the range of operating temperatures, and the ability for all of the material to participate in the thermochemical reactions, i.e. there is no inert support. We present experimental results indicating that pure ceria structures perform at a level comparable to ferrite-based structures with respect to material utilization and better than the ferrites with respect to the carbon monoxide production rate during the oxidation step. We also discuss the performance potential of a solar reactor that continuously produces carbon monoxide using ceria in a two-step thermochemical cycle.</jats:p

Perspectives on being a field-based geomorphologist during pregnancy and early motherhood

Many geomorphologists who are mothers find it challenging to balance field research alongside pregnancy and caring for young children. We offer perspectives on the challenges to conducting fieldwork as mothers and possible solutions, as a means of promoting conversations and highlighting issues that are less commonly considered in field-based geomorphic research. Although every mother's experience and needs are different, we discuss strategies for conducting fieldwork, addressing childcare issues, and dealing with financial considerations. We call for our community to support geomorphologists who are pregnant or caring for young children in carrying out fieldwork to help enhance the diversity of voices and perspectives within our discipline

Shifting stream planform state decreases stream productivity yet increases riparian animal production

In the Colorado Front Range (USA), disturbance history dictates stream planform. Undisturbed, old-growth streams have multiple channels and large amounts of wood and depositional habitat. Disturbed streams (wildfires and logging < 200 years ago) are single-channeled with mostly erosional habitat. We tested how these opposing stream states influenced organic matter, benthic macroinvertebrate secondary production, emerging aquatic insect flux, and riparian spider biomass. Organic matter and macroinvertebrate production did not differ among sites per unit area (m−2), but values were 2 ×–21 × higher in undisturbed reaches per unit of stream valley (m−1 valley) because total stream area was higher in undisturbed reaches. Insect emergence was similar among streams at the per unit area and per unit of stream valley. However, rescaling insect emergence to per meter of stream bank showed that the emerging insect biomass reaching the stream bank was lower in undisturbed sites because multi-channel reaches had 3 × more stream bank than single-channel reaches. Riparian spider biomass followed the same pattern as emerging aquatic insects, and we attribute this to bottom-up limitation caused by the multi-channeled undisturbed sites diluting prey quantity (emerging insects) reaching the stream bank (riparian spider habitat). These results show that historic landscape disturbances continue to influence stream and riparian communities in the Colorado Front Range. However, these legacy effects are only weakly influencing habitat-specific function and instead are primarily influencing stream–riparian community productivity by dictating both stream planform (total stream area, total stream bank length) and the proportional distribution of specific habitat types (pools vs riffles).Griffith Sciences, Australian Rivers InstituteNo Full Tex