ARTICLE | doi:10.20944/preprints202208.0077.v2
Subject: Earth Sciences, Environmental Sciences Keywords: Uranium; Groundwater; Colorado Plateau; Navajo Nation; Chinle Formation
Online: 23 September 2022 (03:38:21 CEST)
Uranium (U) is enriched in the waters of the southern Colorado Plateau, including waters of the Navajo Nation. The region has naturally occurring U in rocks and a history of U mining which may increase U concentrations in waters. Despite prior research into the concentration of U in the waters of the Navajo Nation, a framework has not been established to understand the variation of U in the region’s groundwater. To this end, we examined data from six studies to establish where and why U is likely to be enriched in waters of the southern Colorado Plateau. We show that U concentrations are related to the presence of U-rich rock bodies, elevation, and local aquifer salinity. Additionally, we show that U concentrations in waters downstream from abandoned U mines are higher than in waters that are not downstream from mines, and that the area around mines has an elevated U concentration relative to background U concentrations. Our work can act as a guide for local water withdrawal, regional water remediation and mitigation efforts, and provides a means for understanding the geographical patterns of U concentration in waters of the southern Colorado Plateau.
Subject: Earth Sciences, Geology Keywords: Last Glacial Maximum; paleoclimate; temperature-index model; Sawatch Range; Colorado
Online: 8 September 2019 (15:59:45 CEST)
Temperature-index modeling is used to determine the magnitude of temperature depression in the northern Sawatch Range required to maintain steady-state mass balances of six reconstructed glaciers at their extent during the local Last Glacial Maximum (LLGM), dated at ~21 ka. Assuming no significant differences in precipitation compared to modern values, mean annual temperatures in the region were on average 8.8 +0.5/–0.8 °C cooler than they are today. Allowing for modest increases or decreases in precipitation, required temperature depressions only differ by ± 0.2 °C. Temperature depression in the northern Sawatch Range are consistent, although slightly greater, with those determined in other ranges in Colorado using similar approaches. The estimates presented here are, however, substantially less than those suggested by several downscaled simulations of global LGM climate, that might be due to the need for improved calibration of such downscalings, or the models from which they are derived. Our estimates of LGM temperature depression are considerably greater than that previously determined in the study area and those in two other ranges in Colorado derived using different methodologies, the latter being most likely responsible for the discrepancies.
ARTICLE | doi:10.20944/preprints201908.0294.v1
Subject: Physical Sciences, Mathematical Physics Keywords: time series; Colorado River; water supply; cross-validation; decadal prediction
Online: 28 August 2019 (11:32:10 CEST)
The future of the Colorado River water supply (WS) affects millions of people and the U.S. economy. A recent study suggested a cross-basin correlation between the Colorado River and its neighboring Great Salt Lake (GSL). Following that study, the feasibility of using the previously developed multi-year prediction of the GSL water level to forecast the Colorado River WS was tested. Time-series models were developed to predict the changes in WS out to 10 years. Regressive methods and the GSL water level data were used for the depiction of decadal variability of the Colorado River WS. Various time-series models suggest a decline in the 10-year-averaged WS since 2013 before starting to increase around 2020. Comparison between this WS prediction and the WS projection published in a 2012 government report (derived from climate models) reveals a widened imbalance between supply and demand by 2020. Further research to update similar multi-year prediction of the Colorado River WS is needed. Such information could aid in management decision making in the face of future water shortages.
Subject: Earth Sciences, Geology Keywords: Last Glacial Maximum; paleoclimate; temperature-index model; Blanca Massif; Sangre de Cristo Mountains; Colorado
Online: 11 June 2021 (15:02:15 CEST)
Temperature-index modeling is used to determine the magnitude of temperature depression on the Blanca Massif, Colorado, required to maintain steady-state mass balances of nine reconstructed glaciers at their extent during the Last Glacial Maximum (LGM). The mean temperature depression thus determined is ~8.6 +0.7/–0.9 °C where the uncertainties account for those inherent in the glacier reconstructions, in model parameters (e.g. melt factors), and possible modest changes in LGM precipitation. Associated equilibrium-line altitudes (ELAs) exhibit a statistically significant directional dependency being lower toward the north and east. Under the assumption that regional temperature change was uniform, required changes in precipitation vary systematically – also exhibiting a directional dependency coinciding with that in ELAs – and indicate increases (over modern) occurred on the eastern side of the massif while decreases occurred on the western side. This disparity represents a strengthening of a precipitation asymmetry, particularly winter precipitation, that exists today. The modern precipitation asymmetry may be a consequence of snow being blown over to the eastern side of the massif (advective transport) by southwesterly flow. Intensification of this flow during the LGM would have enhanced advection, and augmented snow accumulation on glaciers, thus explaining the lower ELAs and increased precipitation on that side of the massif.
HYPOTHESIS | doi:10.20944/preprints202007.0100.v2
Subject: Medicine & Pharmacology, Allergology Keywords: amyotrophic lateral sclerosis; ALS; glacial; lake; clay; mineral; United States; Canada; Finland; Vermont; New Hampshire; Maine; Ohio; Wisconsin; Indiana; Minnesota; North Dakota; Montana, Idaho; Washington; Oregon; Colorado; Iowa; Utah
Online: 15 December 2020 (10:21:51 CET)
Amyotrophic lateral sclerosis (ALS) disease clusters are found in several countries worldwide. In the United States, ALS clusters are found in many states, largely within the northern United States. The cause of the increased rates of ALS in these areas remains indefinite. It is reported here that many ALS clusters are associated with sites of current or prior glacial lakes, or regions containing an abundance of silts and clay minerals. The potential significance of these findings in ALS is discussed.