Summary and synthesis of Changing Cold Regions Network (CCRN) research in the interior of western Canada – Part 2: Future change in cryosphere, vegetation, and hydrology

CCRN from the Natural Sciences and Engineering Research Council of Canada (NSERC) through their Climate Change and Atmospheric Research (CCAR) programPeer ReviewedThe interior of western Canada, like many similar cold mid- to high-latitude regions worldwide, is undergoing extensive and rapid climate and environmental change, which may accelerate in the coming decades. Understanding and predicting changes in coupled climate–land– hydrological systems are crucial to society yet limited by lack of understanding of changes in cold-region process responses and interactions, along with their representation in most current-generation land-surface and hydrological models. It is essential to consider the underlying processes and base predictive models on the proper physics, especially under conditions of non-stationarity where the past is no longer a reliable guide to the future and system trajectories can be unexpected. These challenges were forefront in the recently completed Changing Cold Regions Network (CCRN), which assembled and focused a wide range of multi-disciplinary expertise to improve the understanding, diagnosis, and prediction of change over the cold interior of western Canada. CCRN advanced knowledge of fundamental cold-region ecological and hydrological processes through observation and experimentation across a network of highly instrumented research basins and other sites. Significant efforts were made to improve the functionality and process representation, based on this improved understanding, within the fine-scale Cold Regions Hydrological Modelling (CRHM) platform and the large-scale Modélisation Environmentale Communautaire (MEC) – Surface and Hydrology (MESH) model. These models were, and continue to be, applied under past and projected future climates and under current and expected future land and vegetation cover configurations to diagnose historical change and predict possible future hydrological responses. This second of two articles synthesizes the nature and understanding of cold-region processes and Earth system responses to future climate, as advanced by CCRN. These include changing precipitation and moisture feedbacks to the atmosphere; altered snow regimes, changing balance of snowfall and rainfall, and glacier loss; vegetation responses to climate and the loss of ecosystem resilience to wildfire and disturbance; thawing permafrost and its influence on landscapes and hydrology; groundwater storage and cycling and its connections to surface water; and stream and river discharge as influenced by the various drivers of hydrological change. Collective insights, expert elicitation, and model application are used to provide a synthesis of this change over the CCRN region for the late 21st century

The Groundwater Recharge Function of Small Wetlands in the Semi-Arid Northern Prairies

Small wetlands in the semi-arid northern prairie region are focal points for groundwater recharge. Hence the groundwater recharge function of the wetlands is an important consideration in development of wetland conservation policies. Most of the groundwater recharge from the wetlands flows to the moist margins of the wetlands and serves to maintain high evapotranspiration by the vegetation surrounding the wetlands. Only a small portion of the recharged water flows to regional aquifers, but this portion is important for sustaining groundwater resources. Wetland drainage eliminates the local flow systems, but may have little effects on regional aquifers other than a slight lowering of the groundwater levels. Further research should focus on the effects of wetland drainage on regional groundwater levels, the role of small ephemeral ponds in groundwater recharge, and the contribution of groundwater inflow to the water balance of large permanent wetlands

Scattering of light from a plasma jet.

The electron density in a plasma jet has been determined as a function of position in the jet by measurements of the coherent scattering of laser light. The electron density profiles thus obtained are compared with profiles obtained from measurements of spectral line intensities. The results of these two diagnostic methods are seen to agree within experimental error. For the experiment described here, the scattering is from correlated motion of the electrons, and the scattered light spectrum has distinct electron satellites. It is shown that the width of these satellites, observed in earlier work by Chan and Nodwell (1966), may be accounted for by the electron density gradients in the plasma. This thesis gives a short review of techniques and relevant theory, with emphasis on experimental problems. A brief discussion of perturbation of the plasma by the laser light is also included.Science, Faculty ofPhysics and Astronomy, Department ofGraduat

Insights into the genome of large sulfur bacteria revealed by analysis of single filaments

Marine sediments are frequently covered by mats of the filamentous Beggiatoa and other large nitrate-storing bacteria that oxidize hydrogen sulfide using either oxygen or nitrate, which they store in intracellular vacuoles. Despite their conspicuous metabolic properties and their biogeochemical importance, little is known about their genetic repertoire because of the lack of pure cultures. Here, we present a unique approach to access the genome of single filaments of Beggiatoa by combining whole genome amplification, pyrosequencing, and optical genome mapping. Sequence assemblies were incomplete and yielded average contig sizes of approximately 1 kb. Pathways for sulfur oxidation, nitrate and oxygen respiration, and CO2 fixation confirm the chemolithoautotrophic physiology of Beggiatoa. In addition, Beggiatoa potentially utilize inorganic sulfur compounds and dimethyl sulfoxide as electron acceptors. We propose a mechanism of vacuolar nitrate accumulation that is linked to proton translocation by vacuolar-type ATPases. Comparative genomics indicates substantial horizontal gene transfer of storage, metabolic, and gliding capabilities between Beggiatoa and cyanobacteria. These capabilities enable Beggiatoa to overcome non-overlapping availabilities of electron donors and acceptors while gliding between oxic and sulfidic zones. The first look into the genome of these filamentous sulfur-oxidizing bacteria substantially deepens the understanding of their evolution and their contribution to sulfur and nitrogen cycling in marine sediments