scholarly journals Mayotte Critical Zone Observatory: Preliminary Results on Chemical Weathering and Erosion Rates on Volcanic Edifices

2014 ◽  
Vol 10 ◽  
pp. 73-76
Author(s):  
R.-A. Puyraveau ◽  
S. Rad ◽  
I. Basile-Doelsch ◽  
J. Deparis ◽  
T. Jaouën ◽  
...  
Keyword(s):  
Chemical Weathering ◽  
Critical Zone ◽  
Preliminary Results ◽  
Erosion Rates ◽  
Critical Zone Observatory

Chemical weathering and CO2 consumption rate in a multilayered-aquifer dominated watershed under intensive farming: The Orgeval Critical Zone Observatory, France

2018 ◽  
Vol 33 (2) ◽  
pp. 195-213 ◽  
Author(s):  
Paul Floury ◽  
Jérôme Gaillardet ◽  
Gaëlle Tallec ◽  
Patrick Ansart ◽  
Julien Bouchez ◽  
...  
Keyword(s):  
Chemical Weathering ◽  
Consumption Rate ◽  
Critical Zone ◽  
Intensive Farming ◽  
Co2 Consumption ◽  
Critical Zone Observatory

scholarly journals A Multi-Disciplinary Approach to Understand Hydrologic and Geochemical Processes at Koiliaris Critical Zone Observatory

Water ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 2474
Author(s):  
Maria A. Lilli ◽  
Dionissis Efstathiou ◽  
Daniel Moraetis ◽  
Jonathan Schuite ◽  
Sofia D. Nerantzaki ◽  
...  
Keyword(s):  
Chemical Weathering ◽  
River Flow ◽  
Earth Tide ◽  
Soil Management ◽  
Critical Zone ◽  
Periodic Signal ◽  
Geochemical Processes ◽  
Structural Elements ◽  
Flood Events ◽  
Critical Zone Observatory

Koiliaris CZO is a European Critical Zone Observatory (CZO) typical of the Mediterranean karstic geomorphology, which represents watersheds affected by humans over the centuries. This study aims to provide information that underpins the hydrologic and geochemical processes functioning at Koiliaris CZO. Linking geomorphologic and tectonic analysis improved the delineation of a karstic area which extends outside of the Koiliaris watershed and identified how structural elements influence the regional hydrology. The fluctuation in the river flow represents processes occurring in the karst and the periodic signal is related to Earth tide stressing of the karstic reservoirs. The conceptualization of a two-reservoir, well-mixed karstic system is confirmed by both the geomorphologic and tidal analysis. The hydrologic response is fast and it is manifested especially during extreme events where 70% of the precipitation becomes surface runoff, creating major flood events. The different sampling sites in the Koiliaris CZO were geochemically clustered and the quantification of the weathering fluxes showed that 25 mm/1000 years and 39 mm/1000 years of carbonate were removed by chemical weathering for the Keramianos ephemeral river and the springs, respectively. These studies illustrate the importance of critical zone science and transdisciplinary studies on water and soil management.

Dissolved gas (CO2, alkanes, O2, N2) in critical zone developed on claystone

2020 ◽  
Author(s):  
Catherine Lerouge ◽  
Michaela Blessing ◽  
Mathieu Debure ◽  
Frédérick Gal ◽  
Wolfram Kloppmann ◽  
...  
Keyword(s):  
Organic Matter ◽  
Chemical Weathering ◽  
Critical Zone ◽  
Pore Waters ◽  
Dissolved Gas ◽  
French Alps ◽  
Weathering Processes ◽  
Erosion Rates ◽  
Deep Burial ◽  
Gas Seeps

<p><span>Weathering processes in clay environments are of major importance because they participate to regulate elemental cycling and mass transfer in the critical zone with major implications for carbon and nitrogen cycling. </span></p><p><span>In that aim, we measured 1) dissolved CO<sub>2</sub>, alkanes, O<sub>2</sub> and N<sub>2</sub> concentrations in clay pore waters by rock degassing, 2) soil gas flux and concentrations, and 3) δ<sup>13</sup>C of CO<sub>2</sub> and alkanes in two contrasted tectonic contexts. </span></p><p><span>The first context is the marine Jurassic black marls in the French Alps, characterized by deep burial, high erosion rates and dominant physical weathering processes. These marls are well-known for their occurrences of natural methane gas seeps. In this area, we carried out rock degassing on outcropping weathered claystone in complement of soil flux measurements to constrain the implication of weathering processes on the natural gas releases. These measurements are also tested as a new component of environmental baseline assessment in the field of unconventional hydrocarbons.</span></p><p><span>The second context is the marine Cretaceous Tégulines Clay of the north-eastern part of the Paris Basin, characterized by low burial, low erosion rates, and dominant chemical weathering processes. In this area, we carried out rock degassing on soil and weathered claystone accessible by deep boreholes, in order to define the depth of the critical zone and major reactions controlling the weathering profile. </span></p><p><span>Oxygen and nitrogen concentrations are the record of the atmospheric diffusion through the formations. Some values are higher than the gas solubility, which could be attributed to rock desaturation and air bubbles, and clay sorption (only for nitrogen).</span></p><p><span>Weathering processes induce a significant CO<sub>2</sub> increase and a large range of δ<sup>13</sup>C<sub>CO2, </sub>providing evidence of two major CO<sub>2 </sub>sources: CO<sub>2 </sub>internally controlled by carbonates and organic-derived CO<sub>2 </sub>of internal and external origins. In Alpine black marls, field observations suggest a low depth affected by weathering, due to intense erosion. In Tégulines Clay, the CO<sub>2 </sub>increase provides evidence of a ~ 20 m-thick critical zone. The lowest δ<sup>13</sup>C<sub>CO2</sub> indicates that the highest reactive zone (organic matter degradation, calcite dissolution and pyrite oxidation) is ~10 m deep, in agreement with the depth of the root network. </span></p><p><span>Nature and amounts of alkanes are contrasted in the two contexts. In deep burial environment, alkanes are abundant, in particular, in the “ fontaines ardentes” gas seeps in the French Alps. </span><span>Composition of hydrocarbon gas and δ<sup>13</sup>C of methane strongly suggest a thermogenic origin</span><span>. Outcropping black marls contain methane, suggesting oxidation of higher alkanes. That assumption is supported by δ<sup>13</sup>C<sub>CO2</sub> of soil close to δ<sup>13</sup>C of alkanes. In low burial environment, small amounts of methane are present that rapidly disappear with weathering. Some methane concentrations could be attributed to diffusion of external methane formed by degradation of organic matter under reducing conditions in soil. </span></p><p><span>Overall those results suggest that dissolved gas and their isotopic signature are good markers of weathering processes in the critical zone. </span></p><p><span>This research was funded by the EU H2020 Programme (grant 764531 - SECURe), ANDRA-BRGM projects.</span></p><p> </p>

Exploring links between vadose zone hydrology and chemical weathering in the Boulder Creek critical zone observatory

2011 ◽  
Vol 26 ◽  
pp. S70-S71 ◽  
Author(s):  
Abigail L. Langston ◽  
Gregory E. Tucker ◽  
Robert S. Anderson ◽  
Suzanne P. Anderson
Keyword(s):  
Vadose Zone ◽  
Chemical Weathering ◽  
Critical Zone ◽  
Critical Zone Observatory ◽  
Vadose Zone Hydrology

Landscape response to tipping points in granite weathering: The case of stepped topography in the Southern Sierra Critical Zone Observatory

2011 ◽  
Vol 26 ◽  
pp. S48-S50 ◽  
Author(s):  
Barbara S. Jessup ◽  
W. Jesse Hahm ◽  
Scott N. Miller ◽  
James W. Kirchner ◽  
Clifford S. Riebe
Keyword(s):  
Critical Zone ◽  
Tipping Points ◽  
Critical Zone Observatory ◽  
Landscape Response ◽  
Granite Weathering
Sign in / Sign up

Export Citation Format

Share Document