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.

scholarly journals Temporary and net sinks of atmospheric CO<sub>2</sub> due to chemical weathering in subtropical catchment with mixing carbonate and silicate lithology

2020 ◽  
Vol 17 (14) ◽  
pp. 3875-3890
Author(s):  
Yingjie Cao ◽  
Yingxue Xuan ◽  
Changyuan Tang ◽  
Shuai Guan ◽  
Yisheng Peng
Keyword(s):  
Acid Deposition ◽  
Chemical Weathering ◽  
Dissolved Inorganic Carbon ◽  
Silicate Weathering ◽  
Carbonate Weathering ◽  
Weathering Rate ◽  
Weathering Rates ◽  
Hypsometric Integral ◽  
Co2 Sink ◽  
Chemical Weathering Rate

Abstract. The study provided the major ion chemistry, chemical weathering rates and temporary and net CO2 sinks in the Bei Jiang, which was characterized as a hyperactive region with high chemical weathering rates, carbonate and silicate mixing lithology, and abundant sulfuric acid chemical weathering agent of acid deposition and acid mining drainage (AMD) origins. The total chemical weathering rate of 85.46 t km−2 a−1 was comparable to that of other rivers in the hyperactive zones between the latitudes 0 and 30∘. A carbonate weathering rate of 61.15 t km−2 a−1 contributed to about 70 % of the total. The lithology, runoff, and geomorphology had a significant influence on the chemical weathering rate. The proportion of carbonate outcrops had a significant positive correlation with the chemical weathering rate. Due to the interaction between dilution and compensation effect, a significant positive linear relationship was detected between runoff and total carbonate and silicate weathering rates. The geomorphology factors such as catchment area, average slope, and hypsometric integral value (HI) had nonlinear correlation with chemical weathering rate and showed significant scale effect, which revealed the complexity in chemical weathering processes. Dissolved inorganic carbon (DIC) apportionment showed that CCW (carbonate weathering by CO2) was the dominant origin of DIC (35 %–87 %). SCW (carbonate weathering by H2SO4) (3 %–15 %) and CSW (silicate weathering by CO2) (7 %–59 %) were non-negligible processes. The temporary CO2 sink was 823.41×103 mol km−2 a−1. Compared with the temporary sink, the net sink of CO2 for the Bei Jiang was approximately 23.18×103 mol km−2 a−1 of CO2 and was about 2.82 % of the “temporary” CO2 sink. Human activities (sulfur acid deposition and AMD) dramatically decreased the CO2 net sink, even making chemical weathering a CO2 source to the atmosphere.

scholarly journals Temporary and net sinks of atmospheric CO<sub>2</sub> due to chemical weathering in subtropical catchment with mixing carbonate and silicate lithology

2019 ◽  
Author(s):  
Yingjie Cao ◽  
Yingxue Xuan ◽  
Changyuan Tang ◽  
Shuai Guan ◽  
Yisheng Peng
Keyword(s):  
Acid Deposition ◽  
Chemical Weathering ◽  
Silicate Weathering ◽  
Carbonate Weathering ◽  
Weathering Rate ◽  
Weathering Rates ◽  
Beijiang River ◽  
Hypsometric Integral ◽  
Co2 Sink ◽  
Chemical Weathering Rate

Abstract. The study provides the major ion chemistry, chemical weathering rates and temporary and net CO2 sinks in the Beijiang River, which was characterized as hyperactive region with high chemical weathering rates, carbonate and silicate mixing lithology and abundant sulfuric acid chemical weathering agent with acid deposition and AMD origins. The total chemical weathering rate of 85.46 t km−2 a−1 was comparable to other rivers in the hyperactive zones between the latitude 0–30°. Carbonate weathering rates of 61.15 t km−2 a−1 contributed to about 70 % of the total. The lithology, runoff and geomorphology had significant influence on the chemical weathering rate. The proportion of carbonate outcrops had significant positive correlation with the chemical weathering rate. Due to the interaction between dilution and compensation effect, significant positive linear relationship was detected between runoff and total, carbonate and silicate weathering rates. The geomorphology factors such as catchment area, average slope and hypsometric integral value (HI) had non-linear correlation on chemical weathering rate and showed significant scale effect, which revealed the complexity in chemical weathering processes. DIC-apportionment showed that CCW (Carbonate weathering by CO2) was the dominant origin of DIC (35 %–87 %) and that SCW (Carbonate weathering by H2SO4) (3 %–15 %) and CSW (Silicate weathering by CO2) (7 %–59 %) were non-negligible processes. The temporary CO2 sink was 823.41 103 mol km−2 a−1. Compared with the temporary sink, the net sink of CO2 for the Beijiang River was approximately 23.18 × 103 mol km−2 a−1 of CO2 and was about 2.82 % of the temporary CO2 sink. Human activities (sulfur acid deposition and AMD) dramatically decreased the CO2 net sink and even make chemical weathering a CO2 source to the atmosphere.

scholarly journals Supply-limited weathering regime in a tropical shields basin (Ogooué River basin, Gabon)

2020 ◽  
Author(s):  
Jean-Sébastien Moquet ◽  
Julien Bouchez ◽  
Jean-Jacques Braun ◽  
Sakaros Bogning ◽  
Auguste Mbonda ◽  
...  
Keyword(s):  
Chemical Weathering ◽  
Biogeochemical Cycles ◽  
Tectonic Activity ◽  
Silicate Weathering ◽  
Weathering Rate ◽  
Weathering Rates ◽  
Erosion Rates ◽  
The World ◽  
Weathering Intensity

&lt;p&gt;At the global scale and on geological time scales, mechanical erosion and chemical weathering budgets are linked. Together, these processes contribute to the formation and the degradation of the Earth&amp;#8217;s critical zone and to the biogeochemical cycles of elements. While the weathering of hot and humid shields areas exhibit low weathering rates because of the depth of the mature depleted soil mantle there, shields areas dominate the continents areas over intertropical regions and, therefore, represent a significant proportion of the global delivery of dissolved matter to the oceans. In addition, these environments are under supply-limited conditions (the weathering rate is limited by the low rates of the erosion) and thus particularly sensitive to long-term variability erosion rates. Despite this importance, weathering-erosion budgets and rates estimation in these environments is sparse, and generally performed at a local scale (soil profiles) or, when performed at a larger catchment scale, the intra cratonic characteristics variabilities (e. g. the diversity of mechanical erosional regimes) are usually not singled out.&lt;/p&gt;&lt;p&gt;In the present study, we explored the variability of the weathering intensity of the Ogoou&amp;#233; sub-basins (Western central Africa, Gabon) as a function of their geomorphologic, tectonic and lithological setting variability. We analyzed major and trace elements concentration and the strontium and neodymium isotopes of water, suspended matter sediments and bedload sampled in 24 Ogoou&amp;#233; tributaries (September 2017 campaign). Our results show that shield areas exhibit a high variability of chemical weathering intensity, which follows the erosional regime characteristics of the studied sub-basins, likely related to their tectonic activity. Three regions can be distinguished: The Bateke plateau (East sub-basins - PB), is composed of pure sandstones (quartz) and is inert in term of tectonic activity and therefore in term of erosion and weathering budget; the northern sub-basins (NB) are subjected to low tectonic activity and exhibit slightly higher erosion and weathering intensity than PB region and, by comparison, southern sub-basins (SB) exhibits uplift activity which is traduced by more intensive erosion and weathering processes.&lt;/p&gt;&lt;p&gt;The annual dissolved solid budget of the Ogoou&amp;#233; basin is ~2.52 t.yr&lt;sup&gt;-1&lt;/sup&gt; for a rate of 11.7 t.km&lt;sup&gt;-2&lt;/sup&gt;.yr&lt;sup&gt;-1&lt;/sup&gt;. According to the source discrimination method performed based on the geochemical analysis, the atmospheric inputs contributes to around 20% to the TDS, the silicate weathering contribution dominates the dissolved exports throughout 70% of its production while the carbonates weathering lowly contributes to the TDS production.&lt;/p&gt;&lt;p&gt;By comparison to the other large shields rivers, this basin exhibit a lower range of chemical silicate weathering rate than most of the world&amp;#8217;s large rivers, with values similar to those of the Congo River. This new dataset provides a key information to complete the World River chemistry database, which is limited for inter-tropical regions, especially in tectonically quiescent environments. Moreover, this study provides new data for tropical shields contexts allowing for the exploration of the interactions between erosion rates and climate in the control of continental weathering rates, and their relationships with long-term carbon cycle and short-term biogeochemical cycles.&lt;/p&gt;

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

2013 ◽  
Vol 10 (6) ◽  
pp. 8031-8069 ◽  
Author(s):  
W. H. Wu ◽  
H. B. Zheng ◽  
J. D. Yang
Keyword(s):  
Carbonate Rocks ◽  
Chemical Weathering ◽  
Silicate Weathering ◽  
86Sr Ratio ◽  
Sr Isotope ◽  
River Catchment ◽  
Weathering Rates ◽  
Isotopic Compositions ◽  
Isotopic Evolution ◽  
The Pearl River

Abstract. We systematically investigated Sr isotopic characteristics of small silicate watershed – the tributary Xishui River of the Yangtze River, and small carbonate watershed – the tributary Guijiang River of the Pearl River. The results show that the Xishui River has relatively high Sr concentrations (0.468–1.70 μmol L−1 in summer and 1.30–3.17 μmol L−1 in winter, respectively) and low 87Sr/86Sr ratios (0.708686–0.709148 in summer and 0.708515–0.709305 in winter), which is similar to the characteristics of carbonate weathering. The Guijiang River has low Sr concentrations (0.124–1.098 μmol L−1) and high 87Sr/86Sr ratios (0.710558–0.724605), being characterized by silicate weathering. In the Xishui River catchment, chemical weathering rates in summer are far higher than those in winter, indicating significant influence of climate regime. However, slight differences of 87Sr/86Sr ratios between summer and winter show that influence of climate on Sr isotope is uncertainty owing to very similar Sr isotope values in silicate and carbonate bedrocks. As 87Sr/86Sr ratios in the Xishui River are lower than those in seawater, they will decrease 87Sr/86Sr ratio of seawater after transported into oceans. Previous studies also showed 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, it may be questionable that using the variations of seawater 87Sr/86Sr ratio to indicate the continental silicate weathering intensity. In the Guijiang River catchment, 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, 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 over 0.8. Therefore, a few silicate components contained in carbonate rocks obviously increases the Sr isotopic compositions of the river water, and results in a positive effect on the rise of 87Sr/86Sr ratio of seawater. Therefore, the relation between Sr isotope evolution of seawater and continental weathering rate is complex, 87Sr/86Sr ratios of underlying bedrock in catchment could be an important controlling factors.

scholarly journals Co-variation of silicate, carbonate and sulfide weathering drives CO2 release with erosion

2021 ◽  
Vol 14 (4) ◽  
pp. 211-216
Author(s):  
Aaron Bufe ◽  
Niels Hovius ◽  
Robert Emberson ◽  
Jeremy K. C. Rugenstein ◽  
Albert Galy ◽  
...  
Keyword(s):  
Erosion Rate ◽  
Global Climate ◽  
Stream Water ◽  
Sulfide Oxidation ◽  
Silicate Weathering ◽  
Emission Rates ◽  
Mountain Ranges ◽  
Weathering Rates ◽  
Southern Taiwan ◽  
Co2 Release

AbstractGlobal climate is thought to be modulated by the supply of minerals to Earth’s surface. Whereas silicate weathering removes carbon dioxide (CO2) from the atmosphere, weathering of accessory carbonate and sulfide minerals is a geologically relevant source of CO2. Although these weathering pathways commonly operate side by side, we lack quantitative constraints on their co-variation across erosion rate gradients. Here we use stream-water chemistry across an erosion rate gradient of three orders of magnitude in shales and sandstones of southern Taiwan, and find that sulfide and carbonate weathering rates rise with increasing erosion, while silicate weathering rates remain steady. As a result, on timescales shorter than marine sulfide compensation (approximately 106–107 years), weathering in rapidly eroding terrain leads to net CO2 emission rates that are at least twice as fast as CO2 sequestration rates in slow-eroding terrain. We propose that these weathering reactions are linked and that sulfuric acid generated from sulfide oxidation boosts carbonate solubility, whereas silicate weathering kinetics remain unaffected, possibly due to efficient buffering of the pH. We expect that these patterns are broadly applicable to many Cenozoic mountain ranges that expose marine metasediments.

Dating of chemical weathering processes by in situ measurement of U-series disequilibria in supergene Fe-oxy/hydroxides using LA-MC-ICPMS

2006 ◽  
Vol 235 (1-2) ◽  
pp. 76-94 ◽  
Author(s):  
J.P. Bernal ◽  
S.M. Eggins ◽  
M.T. McCulloch ◽  
R. Grün ◽  
R.A. Eggleton
Keyword(s):  
Chemical Weathering ◽  
In Situ Measurement ◽  
Weathering Processes

scholarly journals In Situ Estimation of Carbon Balance of In Vitro Sweetpotato and Tomato Plantlets Cultured with Varying Initial Sucrose Concentrations in the Medium

2002 ◽  
Vol 127 (6) ◽  
pp. 963-970 ◽  
Author(s):  
Chieri Kubota ◽  
Makiko Ezawa ◽  
Toyoki Kozai ◽  
Sandra B. Wilson
Keyword(s):  
Carbon Balance ◽  
Ipomoea Batatas ◽  
Dry Weight ◽  
Photon Flux ◽  
Sugar Uptake ◽  
Relative Contribution ◽  
Carbon Balances ◽  
Species Specific

The effects of initial sucrose (suc) concentrations in the medium (S0) on the carbon balance and growth of sweetpotato [Ipomoea batatas (L.) Lam. `Beniazuma'] and tomato (Lycopersicon esculentum Mill. `HanaQueen') plantlets were studied under controlled environmental conditions. Plantlets were cultured with 0, 7.5, 15, or 30 g·L-1 of S0 under high photosynthetic photon flux (160 to 200 μmol·m-2·s-1) and CO2 enriched (1400 to 2050 μmol·mol-1) conditions. Net photosynthetic rate per leaf area (Pl) decreased and dry weight per plantlet (Wd) increased with increasing S0, but did not differ significantly between S0 of 7.5 to 30 g·L-1 for sweetpotato or 15 to 30 g·L-1 for tomato. Carbon influxes and effluxes of the plantlets by metabolism of medium suc and/or photosynthesis, and respiration were estimated based on measurements of in situ and steady state CO2 exchange rates and sugar uptake during culture. At S0 from 7.5 to 30 g·L-1, photosynthesis was responsible for 82% to 92% and 60% to 67% of carbohydrate assimilation for sweetpotato and tomato, respectively. Estimated carbon balances of plantlets based on the estimated and actual increases of moles of carbon in plant tissue demonstrated that in situ estimation of carbon balance was reasonably accurate for sweetpotato at S0 of 0 to 15 g·L-1 and for tomato at S0 of 0 g·L-1 and that the actual contribution of photosynthesis for tomato at high S0 might be lower than the values estimated in the present experiment. Results showed that initial suc concentration affected the relative contribution of photosynthesis on their carbon balances and that the responses were species specific. The failure of validation at S0 in a range specific to each species suggested the need for further study on carbon metabolism of in vitro plantlets cultured with sugar in the medium.

scholarly journals Low hydrological connectivity after summer drought inhibits DOC export in a forested headwater catchment

2021 ◽  
Vol 25 (9) ◽  
pp. 5133-5151
Author(s):  
Katharina Blaurock ◽  
Burkhard Beudert ◽  
Benjamin S. Gilfedder ◽  
Jan H. Fleckenstein ◽  
Stefan Peiffer ◽  
...  
Keyword(s):  
Riparian Zone ◽  
Hysteresis Loops ◽  
Hydrological Connectivity ◽  
Summer Drought ◽  
Carbon Cycles ◽  
Relative Contribution ◽  
Doc Export ◽  
Key Driver ◽  
Doc Load

Abstract. Understanding the controls on event-driven dissolved organic carbon (DOC) export is crucial as DOC is an important link between the terrestrial and the aquatic carbon cycles. We hypothesized that topography is a key driver of DOC export in headwater catchments because it influences hydrological connectivity, which can inhibit or facilitate DOC mobilization. To test this hypothesis, we studied the mechanisms controlling DOC mobilization and export in the Große Ohe catchment, a forested headwater in a mid-elevation mountainous region in southeastern Germany. Discharge and stream DOC concentrations were measured at an interval of 15 min using in situ UV-Vis (ultraviolet–visible) spectrometry from June 2018 until October 2020 at two topographically contrasting subcatchments of the same stream. At the upper location (888 m above sea level, a.s.l.), the stream drains steep hillslopes, whereas, at the lower location (771 m a.s.l.), it drains a larger area, including a flat and wide riparian zone. We focus on four events with contrasting antecedent wetness conditions and event size. During the events, in-stream DOC concentrations increased up to 19 mg L−1 in comparison to 2–3 mg L−1 during baseflow. The concentration–discharge relationships exhibited pronounced but almost exclusively counterclockwise hysteresis loops which were generally wider in the lower catchment than in the upper catchment due to a delayed DOC mobilization in the flat riparian zone. The riparian zone released considerable amounts of DOC, which led to a DOC load up to 7.4 kg h−1. The DOC load increased with the total catchment wetness. We found a disproportionally high contribution to the total DOC export of the upper catchment during events following a long dry period. We attribute this to the low hydrological connectivity in the lower catchment during drought, which inhibited DOC mobilization, especially at the beginning of the events. Our data show that not only event size but also antecedent wetness conditions strongly influence the hydrological connectivity during events, leading to a varying contribution to DOC export of subcatchments, depending on topography. As the frequency of prolonged drought periods is predicted to increase, the relative contribution of different subcatchments to DOC export may change in the future when hydrological connectivity will be reduced more often.

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