scholarly journals Reconciling Chemical Weathering Rates Across Scales: Insights from U-Series Isotopes in Volcanic Weathering Clasts from Basse-Terre Island (Guadeloupe)

2020 ◽  
Author(s):  
Lin Ma ◽  
Jiye Guo ◽  
Yvette Pereyra ◽  
Jacqueline Engel ◽  
Jerome Gaillardet ◽  
...  
Keyword(s):  
Chemical Weathering ◽  
Weathering Rates

scholarly journals Chemical weathering rates and atmospheric/soil CO2 consumption of igneous and metamorphic rocks under tropical climate in southeastern Brazil

2016 ◽  
Vol 443 ◽  
pp. 54-66 ◽  
Author(s):  
Alexandre Martins Fernandes ◽  
Fabiano Tomazini da Conceição ◽  
Eder Paulo Spatti Junior ◽  
Diego de Souza Sardinha ◽  
Jeferson Mortatti
Keyword(s):  
Chemical Weathering ◽  
Tropical Climate ◽  
Southeastern Brazil ◽  
Metamorphic Rocks ◽  
Soil Co2 ◽  
Weathering Rates ◽  
Co2 Consumption

scholarly journals The rate of chemical weathering beneath a quiescent, surge-type, polythermal-based glacier, southern Spitsbergen, Svalbard

1997 ◽  
Vol 24 ◽  
pp. 27-31 ◽  
Author(s):  
J. L. Wadham ◽  
A. J. Hodson ◽  
M. Tranter ◽  
J. A. Dowdeswell
Keyword(s):  
Thermal Regime ◽  
Chemical Weathering ◽  
High Arctic ◽  
Direct Link ◽  
Water Fluxes ◽  
Weathering Rate ◽  
Weathering Rates ◽  
Pertinent Data ◽  
Chemical Weathering Rate ◽  
Annual Discharge

Glacierized basins in the high Arctic are believed to be regions of low chemical weathering rates, despite the lack of pertinent data, because it is believed that water does not flow in significant quantities through subglacial drainage systems. We have calculated chemical weathering rates at Finsterwalderbreen, a polythermal, surge-type glacier in Svalbard. Rates of 320 and 150 meq Σ+ m−1 year−1 were measured in 1994 and 1995, respectively. The corresponding water fluxes were 4.1 × 107 and 1.7 × 107 m3. We estimate that we have measured ~72% of the total annual discharge, hence the true annual chemical weathering rates are ~440 and 210 meq Σ+ m−2 year−1, respectively This gives a mean annual chemical weathering rate of 330 meq Σ+ m−2 year−1, which approximates the continental average of 390 meq Σ+ m−2 year−1 and is intermediate between chemical weathering rates measured on cold-based glaciers (~110–160 meq Σ+ m−2 year−1) and temperate glaciers (450–1000 meq Σ+ m−2 year−1). This suggests that there may be a direct link between chemical weathering rates and thermal regime, and that glacierized basins in the high Arctic cannot necessarily be considered as regions of low chemical weathering and CO2 drawdown.

scholarly journals Direct measurement of fungal contribution to silicate weathering rates in soil

Geology ◽  
2021 ◽  
Author(s):  
Bastien Wild ◽  
Gwenaël Imfeld ◽  
Damien Daval
Keyword(s):  
Chemical Weathering ◽  
Silicate Weathering ◽  
Nutrient Fluxes ◽  
Weathering Rates ◽  
Relative Contribution ◽  
Quantitative Estimates ◽  
Fungal Hyphae ◽  
Nanoscale Topography ◽  
Natural Settings

Chemical weathering produces solutes that control groundwater chemistry and supply ecosystems with essential nutrients. Although microbial activity influences silicate weathering rates and associated nutrient fluxes, its relative contribution to silicate weathering in natural settings remains largely unknown. We provide the first quantitative estimates of in situ silicate weathering rates that account for microbially induced dissolution and identify microbial actors associated with weathering. Nanoscale topography measurements showed that fungi colonizing olivine [(Mg,Fe)2SiO4] samples in a Mg-deficient forest soil accounted for up to 16% of the weathering flux after 9 mo of incubation. A local increase in olivine weathering rate was measured and attributed to fungal hyphae of Verticillium sp. Altogether, this approach provides quantitative parameters of bioweathering (i.e., rates and actors) and opens new avenues to improve elemental budgets in natural settings.

scholarly journals Sr isotopic characteristics in two small watersheds draining silicate and carbonate rocks: implication for studies on seawater Sr isotopic evolution

2014 ◽  
Vol 18 (2) ◽  
pp. 559-573
Author(s):  
W. H. Wu ◽  
H. B. Zheng ◽  
J. H. Cao ◽  
J. D. Yang
Keyword(s):  
River Water ◽  
Carbonate Rocks ◽  
Chemical Weathering ◽  
Silicate Weathering ◽  
86Sr Ratio ◽  
Weathering Rates ◽  
Isotopic Compositions ◽  
Small Watersheds ◽  
Isotopic Evolution ◽  
The Pearl River

Abstract. We systematically investigated the Sr isotopic characteristics of a small silicate watershed, the Xishui River a tributary of the Yangtze River, and a small carbonate watershed, the Guijiang River a tributary of the Pearl River. The results show that the two rivers have uncommon Sr isotopic characteristics compared with most small watersheds. Specifically, the silicate watershed (Xishui River) has relatively high Sr concentrations (0.468 to 1.70 μmol L−1 in summer and 1.30 to 3.17 μmol L−1 in winter, respectively) and low 87Sr/86Sr ratios (0.708686 to 0.709148 in summer and 0.708515 to 0.709305 in winter). The carbonate watershed (Guijiang River) has low Sr concentrations (0.124 to 1.098 μmol L−1) and high 87Sr/86Sr ratios (0.710558 to 0.724605). As the 87Sr/86Sr ratios in the Xishui River are lower than those in seawater, the 87Sr/86Sr ratio of seawater will decrease after the river water is transported to the oceans. Previous studies have also shown that some basaltic watersheds with extremely high chemical weathering rates reduced the seawater Sr isotope ratios. In other words, river catchments with high silicate weathering rates do not certainly transport highly radiogenic Sr into oceans. Therefore, the use of the variations in the seawater 87Sr/86Sr ratio to indicate the continental silicate weathering intensity may be questionable. In the Guijiang River catchment, the 87Sr/86Sr ratios of carbonate rocks and other sources (rainwater, domestic and industrial waste water, and agricultural fertilizer) are lower than 0.71. In comparison, some non-carbonate components, such as sand rocks, mud rocks, and shales, have relatively high Sr isotopic compositions. Moreover, granites accounted for only 5% of the drainage area have extremely high 87Sr/86Sr ratios with an average of greater than 0.8. Therefore, a few silicate components in carbonate rocks obviously increase the Sr isotopic compositions of the river water.

Sign in / Sign up

Export Citation Format

Share Document