Search

Warming and thawing in the Arctic are promoting biogeochemical processing and hydrologic transport in carbon‐rich permafrost and soils that transfer carbon to surface waters or the atmosphere. Hydrologic and biogeochemical impacts of thawing are challenging to predict with sparse information on arctic soil hydraulic and thermal properties. We developed empirical and statistical models of soil properties for three main strata in the shallow, seasonally thawed soils above permafrost in a study area of ~7,500 km2 in Alaska. The models show that soil vertical stratification and hydraulic properties are predictable based on vegetation cover and slope. We also show that the distinct hydraulic and thermal properties of each soil stratum can be predicted solely from bulk density. These findings fill the gap for a sparsely mapped region of the Arctic and enable regional interpolation of soil properties critical for determining future hydrologic responses and the fate of carbon in thawing permafrost. Plain Language Summary: Arctic permafrost holds about as much carbon as currently present in the atmosphere. Rapid warming in the Arctic has raised concerns that this stored carbon could thaw and get released into the atmosphere, which would substantially amplify global warming. The rate of this carbon release to the atmosphere depends on the rate of environmental processes such as microbial respiration and heat and groundwater flow. The soil properties controlling these processes are currently unknown across most of the Arctic, making predictions of the processes highly uncertain at larger scales. This study uses hundreds of measurements of soil properties across an area of land larger than Delaware to show that soil properties in the foothills of the Brooks Range in northern Alaska are predictable if the landscape slope, dominant vegetation type, and local topography are known. This study provides a base for calculating transport processes related to soil carbon in the Arctic. Key Points: Thermal and hydraulic properties of 265 permafrost soil samples from across the Arctic foothills of Alaska were measuredDifferent soil strata (acrotelm, catotelm, and mineral soil) have consistent properties and thickness over hundreds of kilometersThe soil properties are strongly related to vegetation and surface slope and can be independently predicted from soil bulk density [ABSTRACT FROM AUTHOR]

Summary Deltas in coastal environments are assumed to function as chemical “buffers”, filtering nutrient-rich terrestrial runoff through the island structures and aquatic ecosystems as it travels to the sea, but the magnitude of this effect cannot be accurately quantified without understanding the physical relationships between the surface water and groundwater. The groundwater hydrology of young, prograding delta systems and its relationship to surrounding surface water dynamics are poorly understood. This study developed a new conceptual model of the hydrology of a prograding delta island groundwater system. The study was based on field data collected at Pintail Island, a 2 km 2 island within the Wax Lake Delta in Louisiana. Hydraulic properties and processes were quantified at multiple depths and locations spanning the island elevation gradient. Groundwater and surface water levels were monitored. A weather station recorded precipitation, air, and wind conditions. The groundwater within Pintail Island was both spatially and temporally dynamic throughout the study period of 9-September-2013 to 4-February-2014. The aquifer within the distal limbs of the island responded to surface water dynamics as a connected, saturated unconfined aquifer would, and its groundwater was controlled by the surrounding surface water fluctuations of semi-diurnal winds and tides. The aquifer within the older, higher elevation island apex was a lower-permeability system with subaerial fine sediments overlying deeper, sandier sediments. In contrast to the more bayward zone of the island, this more interior zone was controlled by storm recharge, low-permeability sediments, and low head gradients, but little affected by diurnal surface water fluctuations. Groundwater flow was directed outward from the interior of the island apex and the levees toward the delta channels and the central island lagoon, but storms and high tides temporarily reversed flow directions at some locations and times, likely with significant biogeochemical consequences. This empirically-based conceptual model of the heterogeneous and dynamic hydrogeology of a young, prograding delta island provides an essential foundation for further study of prograding coastal delta island hydrology, ecology, and nutrient exchange. [ABSTRACT FROM AUTHOR]

How do Catholic schools create inclusive, equitable environments that embrace the identities of their students, including their race, ethnicity, and culture What does Catholic theological spirituality say about diversity, equity, and inclusion to address racism What is the connection between Catholic theological spirituality and equitable school practices to bring about equity in Catholic schools In response to increased diversity of students, educators, communities, and societal challenges, there is a need for a framework for Catholic schools with a culturally diverse student body, or with a student body and staff with different cultures. We synthesize Catholic theological spirituality and research about equity in public and Catholic schools to create a framework for Catholic school educators in their support of students whose cultural identity is different from the faculty and staff. The framework uses Catholic theological spirituality and equitable school practices to promote equity in Catholic schools using equitable school practices. [ABSTRACT FROM AUTHOR]

Abstract: Groundwater flow regimes in the seasonally thawed soils in areas of continuous permafrost are relatively unknown despite their potential role in delivering water, carbon, and nutrients to streams. Using numerical groundwater flow models informed by observations from a headwater catchment in arctic Alaska, United States, we identify several mechanisms that result in substantial surface‐subsurface water exchanges across the land surface during downslope transport and create a primary control on dissolved organic carbon loading to streams and rivers. The models indicate that surface water flowing downslope has a substantial groundwater component due to rapid surface‐subsurface exchanges across a range of hydrologic states, from unsaturated to flooded. Field‐based measurements corroborate the high groundwater contributions, and river dissolved organic carbon concentrations are similar to that of groundwater across large discharge ranges. The persistence of these groundwater contributions in arctic watersheds will influence carbon export to rivers as thaw depth increases in a warmer climate. [ABSTRACT FROM AUTHOR]