Origin and variability of oxygen and hydrogen isotopic composition of precipitation in the Central Andes: A review

Characterization of lithium cycling in the Salar De Olaroz, Central Andes, using a geochemical and isotopic approach

Resumen en: Samples of rain have been collected on arid Altiplano of Northern Chile and Southern Bolivia between July 1994 and March 1997. An automatic meteorologica...

Précipitationd'altitude du nord-Chili, origine des sources de vapeur et données isotopiques

1 1 Water Resources Research 2 3 Stable and Radioisotope Systematics Reveal Fossil Water as 4 Fundamental Characteristic of Arid Orogenic-Scale Groundwater 5 Systems 6 7 Brendan J. Moran (ORCID = 0000-0002-9862-6241)1, David F. Boutt (ORCID = 00008 0003-1397-0279)1, Lee Ann Munk (ORCID =0000-0003-2850-545X)2 9 10 1 Department of Geosciences, University of Massachusetts-Amherst, Amherst, MA, USA 11 2 Department of Geological Sciences, 3101 Science Circle, University of Alaska12 Anchorage, Anchorage, AK, USA 13 14 Corresponding author: Brendan J. Moran (bmoran@geo.umass.edu) 15 16 17 18 19 20 21 22 Key points 23

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Stable and Radioisotope Systematics Reveal Fossil Water as Fundamental Characteristic of Arid Orogenic-Scale Groundwater Systems

Purpose of ReviewUnderstanding the details of the impact of global warming on the North and South America monsoons is of key importance for the well-being of a great number of inhabitants of the Americas. This review deals with the latest research on this topic.Recent FindingsCombined multiple datasets, high-resolution global climate models and regional convection–permitting models provide new insights on the evolution of the North and South American monsoons under global warming, suggesting a precipitation reduction in the North American Monsoon, the southward shift of the core of the South American Monsoon, and precipitation reduction in the Amazon Basin. These changes are accompanied by increased frequency of extreme precipitation events in both monsoon regions.SummaryUncertainty in the response mechanisms to global warming remains high, especially for the North American monsoon. To make progress, the evaluation of local and remote drives is critical, for which we need a combined use of regional and global models.

Current and Future Variations of the Monsoons of the Americas in a Warming Climate

Hydrogeochemical fluxes and processes contributing to the formation of lithium-enriched brines in a hyper-arid continental basin

Hydrogeologic and Geochemical Distinctions in Freshwater-Brine Systems of an Andean Salar

Modern rates of water discharge often exceed groundwater recharge in arid catchments. This apparent mass imbalance within a catchment may be reconciled through either groundwater flow between topographic drainages and/or the draining of stored groundwater recharged during pluvial periods. This study investigates discrepancies in the modern hydrologic budget of catchments along the west flank of the Andes in northern Chile (21–25° S), focusing on the endorheic Salar de Atacama basin and adjacent basins. Uncertainty-bounded estimates of modern recharge rates are presented, which do not come close to balancing observed modern groundwater discharge within topographic catchments. Two conceptualizations of hydrogeologic catchments discharging to Salar de Atacama were explored with a simplified two-dimensional groundwater model. Results from the models support the interpretation that subsurface interbasin flow and transient drainage of groundwater from storage are required to balance water budgets along the plateau margin. The models further examine whether this system is still responding to climatic forcing (on paleoclimatic time scales) from pluvial periods and highlight general characteristics for similar plateau margin systems including: (1) water level changes at the plateau margin that are highly sensitive to long-term (100–1,000 years) changes in recharge on the plateau, (2) extent and magnitude of the changes in water table, which are controlled by the distribution of hydraulic conductivity at the margin, and (3) the contributing area to the lower-elevation catchment, which is itself dynamic and not coincident with the topographic boundary.

Imbalance in the modern hydrologic budget of topographic catchments along the western slope of the Andes (21–25°S): implications for groundwater recharge assessment

High-elevation wetlands in South America are not well described despite their high sensitivity to human impact and unique biodiversity. We describe the hydroclimatological and limnological characteristics of 21 wetlands on the High Andean Plateau of Argentina, synthesizing information gathered over ten years (2010–2020). We collected physical-chemical, phytoplankton, and zooplankton data and counted flamingos in each wetland. We also conducted an extensive analysis of climatic patterns and hydrological responses since 1985. These wetlands are shallow, with a wide range of salinity (from fresh to brine), mostly alkaline, and are dominated by carbonate and gypsum deposits and sodium-chloride waters. They tend to have high nutrient concentrations. Plankton shows a low species richness and moderate to high dominance of taxa. Flamingos are highly dependent on the presence of Bacillariophyta, which appears to be positively linked to silica and soluble reactive phosphorus availability. Climatic conditions show a strong region-wide increase in average air temperature since the mid-1980s and a decrease in precipitation between 1985–1999 and 2000–2020. These high-elevation wetlands are fundamentally sensitive systems; therefore, having baseline information becomes imperative to understanding the impact of climatic changes and other human perturbations. This work attempts to advance the body of scientific knowledge of these unique wetland systems.

Brendan J. Moran

Papers

Hydrogeochemical fluxes and processes contributing to the formation of lithium-enriched brines in a hyper-arid continental basin

Stable and Radioisotope Systematics Reveal Fossil Water as Fundamental Characteristic of Arid Orogenic-Scale Groundwater Systems

Hydrogeologic and Geochemical Distinctions in Freshwater-Brine Systems of an Andean Salar

Imbalance in the modern hydrologic budget of topographic catchments along the western slope of the Andes (21–25°S): implications for groundwater recharge assessment

Hydroclimatological Patterns and Limnological Characteristics of Unique Wetland Systems on the Argentine High Andean Plateau