“…Coupling isotopic data to reactive transport models may yield insights into connections among concentration‐discharge relationships and streamflow sources (L. Li, et al, ). More frequent research that combines geochemical‐based approaches with other techniques used to evaluate groundwater discharges could improve conceptual models describing groundwater connections with surface waters (geophysics—Harrington et al, ; temperature profiles—Xu et al, ; piezometric and solute concentration data—Rhodes et al, ; and measurements of well water levels along river corridors to quantify hydraulic gradients—Cook, ). Synoptic sampling of river waters has helped quantify groundwater discharges along rivers spanning approximately ones to tens of kilometers (Beisner et al, ; Campodonico et al, ; Harrington et al, ; Smerdon et al, ). Multiple geochemical tracers are measured and applied to assess groundwater inputs along rivers, including radiocarbon (Bourke et al, ), radon‐222 (e.g., Cook et al, , ; Cook, ; Cartwright et al, ; Campodonica et al, 2015; Cartwright & Gilfedder, ; Cartwright & Hofmann, ; Xie et al, ; Xu et al, ; Avery et al, ), helium‐4 (Gardner et al, ), and chloride or other major ion concentrations, strontium isotopes (e.g., Négrel et al, ; Shand et al, ).…”
Section: Groundwater Discharges To Riversmentioning
Groundwater 18O/16O, 2H/1H, 13C/12C, 3H, and 14C data can help quantify molecular movements and chemical reactions governing groundwater recharge, quality, storage, flow, and discharge. Here, commonly applied approaches to isotopic data analysis are reviewed, involving groundwater recharge seasonality, recharge elevations, groundwater ages, paleoclimate conditions, and groundwater discharge. Reviewed works confirm and quantify long held tenets: (i) that recharge derives disproportionately from wet season and winter precipitation; (ii) that modern groundwaters comprise little global groundwater; (iii) that “fossil” (>12,000‐year‐old) groundwaters dominate global aquifer storage; (iv) that fossil groundwaters capture late‐Pleistocene climate conditions; (v) that surface‐borne contaminants are more common in younger groundwaters; and (vi) that groundwater discharges generate substantial streamflow. Groundwater isotope data are disproportionately common to midlatitudes and sedimentary basins equipped for irrigated agriculture, but less plentiful across high latitudes, hyperarid deserts, and equatorial rainforests. Some of these underexplored aquifer systems may be suitable targets for future field testing.
“…Coupling isotopic data to reactive transport models may yield insights into connections among concentration‐discharge relationships and streamflow sources (L. Li, et al, ). More frequent research that combines geochemical‐based approaches with other techniques used to evaluate groundwater discharges could improve conceptual models describing groundwater connections with surface waters (geophysics—Harrington et al, ; temperature profiles—Xu et al, ; piezometric and solute concentration data—Rhodes et al, ; and measurements of well water levels along river corridors to quantify hydraulic gradients—Cook, ). Synoptic sampling of river waters has helped quantify groundwater discharges along rivers spanning approximately ones to tens of kilometers (Beisner et al, ; Campodonico et al, ; Harrington et al, ; Smerdon et al, ). Multiple geochemical tracers are measured and applied to assess groundwater inputs along rivers, including radiocarbon (Bourke et al, ), radon‐222 (e.g., Cook et al, , ; Cook, ; Cartwright et al, ; Campodonica et al, 2015; Cartwright & Gilfedder, ; Cartwright & Hofmann, ; Xie et al, ; Xu et al, ; Avery et al, ), helium‐4 (Gardner et al, ), and chloride or other major ion concentrations, strontium isotopes (e.g., Négrel et al, ; Shand et al, ).…”
Section: Groundwater Discharges To Riversmentioning
Groundwater 18O/16O, 2H/1H, 13C/12C, 3H, and 14C data can help quantify molecular movements and chemical reactions governing groundwater recharge, quality, storage, flow, and discharge. Here, commonly applied approaches to isotopic data analysis are reviewed, involving groundwater recharge seasonality, recharge elevations, groundwater ages, paleoclimate conditions, and groundwater discharge. Reviewed works confirm and quantify long held tenets: (i) that recharge derives disproportionately from wet season and winter precipitation; (ii) that modern groundwaters comprise little global groundwater; (iii) that “fossil” (>12,000‐year‐old) groundwaters dominate global aquifer storage; (iv) that fossil groundwaters capture late‐Pleistocene climate conditions; (v) that surface‐borne contaminants are more common in younger groundwaters; and (vi) that groundwater discharges generate substantial streamflow. Groundwater isotope data are disproportionately common to midlatitudes and sedimentary basins equipped for irrigated agriculture, but less plentiful across high latitudes, hyperarid deserts, and equatorial rainforests. Some of these underexplored aquifer systems may be suitable targets for future field testing.
“…The comprehension of the processes controlling the water chemistry of a river is useful to define geochemical cycles within a given catchment (Mohammed et al 2014;Campodonico et al 2015;Harker et al 2015). Although natural studies of riverine chemistry at the global scale have been widely discussed (Gibbs 1970;Meybeck 2003;Gaillardet et al 1999;Gaillardet 2014;Viers et al 2014), specific regional researches performed on the Adige River catchment are incomplete (i.e., considering only few parameters) and never available for the whole stream path (Chiogna et al 2016).…”
Section: Origin Of the Dissolved Componentsmentioning
confidence: 99%
“…The current contribution intends to fill this gap of knowledge and is inspired to recent studies of other riverine systems (Mohammed et al 2014;Campodonico et al 2015;Harker et al 2015). The goal can be achieved combining classical hydrological approaches with a geochemical investigation at a basin scale that is a powerful tool to identify the water provenance and origin, as well as to highlight local variations induced by anthropogenic activities.…”
The Adige River flows from the Eastern Alps to the Adriatic Sea and the understanding of its fluvial dynamics can be improved by geochemical and O-H isotopic investigation. The most negative isotopic compositions are recorded close to the source (δ(18)O between -14.1 and -13.8 ‰, δD between -100.3 and -97.0 ‰), and δD and δ(18)O values generally increase downstream through the upper part (UP, the mountainous sector), stabilizing along the lower part (LP, the alluvial plain) of the river with δ(18)O between -12.4 and -11.8 ‰, δD between -86.9 and -83.7 ‰. The isotopic variations along the stream path (δ(18)O-δD vs distance from the source) depict subparallel distributions for all the investigated periods, with less negative values recorded in winter. Total dissolved solids (TDS) concentration shows the lowest value (<100 mg/l) at the river source, jumping to 310 mg/l at the Rio Ram inflow, then decreasing down to the Isarco River confluence; from here, we observed an increase toward the river mouth, with different values in the distinct sampling periods. The lowest values (140-170 mg/l) were recorded during high discharge in spring, whereas higher TDS values (up to 250 mg/l) were recorded during winter low flow conditions. Extreme TDS values were observed in the estuarine samples (up to 450 mg/l), as result of mixing with seawater. The results allow for the identification of distinct water end-members: glacio-nival component(s) characterized by the most negative isotopic composition and extremely low TDS, a rainfall component characterized by intermediate isotopic and elemental composition and groundwater characterized by the less negative isotopic composition and comparatively higher TDS. An additional component is represented by seawater, which is recorded at the lowest reach of the river during drought periods. These contributions variously mix along the stream path in the distinct hydrological periods, and the presented data are a snapshot of the current hydroclimatic conditions. Future investigations will evaluate possible hydrological variations related to meteo-climatic changes. Monitoring is fundamental for future water management to overcome the vanishing of a significant water end-member of the basin, i.e., the glacio-nival reservoir that is severely affected by the ongoing climatic changes.
“…It should be noted that REE compositions of both oceanic and continental hydrothermal fluids are very flexible, depending on the composition of interacting rocks.Figure 5REE in prokaryotes versus ( a ) their contents in nutrient media (1-REE ratios for cells before and 2-after washing procedure) and ( b ) selected rocks and fluids. The C1 normalized plots are shown for Mount Roe basalt paleosol (MR#1 20 ), Paraná basalt, upper continental crust 41 , mean trends for continental and oceanic hydrothermal fluids 43 , Upper Paraná river water draining the Paraná basalts 75 and seawater 76 . The median (dark cyan) is plotted for archaea (dark green), E. coli (dark yellow) and other bacteria (light green).…”
The environmental conditions on the Earth before 4 billion years ago are highly uncertain, largely because of the lack of a substantial rock record from this period. During this time interval, known as the Hadean, the young planet transformed from an uninhabited world to the one capable of supporting, and inhabited by the first living cells. These cells formed in a fluid environment they could not at first control, with homeostatic mechanisms developing only later. It is therefore possible that present-day organisms retain some record of the primordial fluid in which the first cells formed. Here we present new data on the elemental compositions and mineral fingerprints of both Bacteria and Archaea, using these data to constrain the environment in which life formed. The cradle solution that produced this elemental signature was saturated in barite, sphene, chalcedony, apatite, and clay minerals. The presence of these minerals, as well as other chemical features, suggests that the cradle environment of life may have been a weathering fluid interacting with dry-land silicate rocks. The specific mineral assemblage provides evidence for a moderate Hadean climate with dry and wet seasons and a lower atmospheric abundance of CO2 than is present today.
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