Carbonate and silicate weathering in glacial environments and its relation to atmospheric CO2 cycling in the Himalaya

ABSTRACTThis paper presents new insights into the global carbon cycle related to CO2 consumption from chemical denudation in heavily glacierised Himalayan catchments. Data from previous studies of solute concentrations from glacierised catchments were reprocessed to determine the regional scale of CO2 consumption and solute hydrolysis. The results show that ~90% of the SO42− is derived from crustal sulphide oxidation and ~10% from aerosols and sea salts. However, HCO3− flux calculation estimates contribution from sulphide oxidation to carbonate dissolution (SO-CD) (~21%), similar to the contributions from silicate dissolution and simple hydrolysis (~21 and ~20%, respectively). Furthermore, the atmospheric CO2 consumption estimations suggests 10.6 × 104 mole km−2 a−1 (19%) through silicate weathering, 15.7 × 104 mole km−2 a−1 (28%) through simple hydrolysis, 9.6 × 104 mole km−2 a−1 (17%) through SO-CD reaction and 5.9 × 104 mole km−2 a−1 (11%) through carbonate carbonation reaction. Our solute provenance calculations clearly indicate that HCO3− production and CO2 consumption via silicate weathering reactions is balanced by the simple hydrolysis and coupled SO-CD process. This shows a counter mechanism operating in subglacial environments of the Himalaya as a source of CO2 to runoff rather than a sink.

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Weak impact of microorganisms on Ca, Mg-bearing silicate weathering

npj Materials Degradation ◽

10.1038/s41529-021-00199-w ◽

2021 ◽

Vol 5 (1) ◽

Author(s):

Oleg S. Pokrovsky ◽

Liudmila S. Shirokova ◽

Svetlana A. Zabelina ◽

Guntram Jordan ◽

Pascale Bénézeth

Keyword(s):

Heterotrophic Bacterium ◽

Soil Fungus ◽

Mineral Dissolution ◽

Ex Situ ◽

Silicate Weathering ◽

Batch Reactors ◽

Basaltic Rocks ◽

Silicate Dissolution ◽

Predictive Understanding ◽

Ph Decrease

AbstractAssessment of the microbial impact on mineral dissolution is crucial for a predictive understanding of basic (Ca, Mg bearing) silicate weathering and the associated CO2 consumption, bioerosion, and CO2 storage in basaltic rocks. However, there are controversies about the mechanism of microbial effect, which ranges from inhibiting via nil to accelerating. Here we studied diopside interaction with the heterotrophic bacterium Pseudomonas reactants and the soil fungus Chaetomium brasiliense using a combination of mixed-flow and batch reactors and in situ (AFM) and ex situ (SEM) microscopy. The results provide new nano-level insights into the degree to which microorganisms modify silicate dissolution. Taking into account negligible effects of organic ligands on diopside dissolution as reported earlier, we conclude that the microbial effect on Ca-Mg silicates is weak and the acceleration of dissolution of “basic” silicate rocks in the presence of soil biota is solely due to pH decrease in porewaters.

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Glacial lakes exacerbate Himalayan glacier mass loss

Scientific Reports ◽

10.1038/s41598-019-53733-x ◽

2019 ◽

Vol 9 (1) ◽

Cited By ~ 18

Author(s):

Owen King ◽

Atanu Bhattacharya ◽

Rakesh Bhambri ◽

Tobias Bolch

Keyword(s):

Mass Loss ◽

Regional Scale ◽

High Mountain ◽

Mass Balances ◽

Glacial Lakes ◽

Regional Variability ◽

Glacier Recession ◽

Minor Portion ◽

A Minor ◽

The Himalaya

AbstractHeterogeneous glacier mass loss has occurred across High Mountain Asia on a multi-decadal timescale. Contrasting climatic settings influence glacier behaviour at the regional scale, but high intra-regional variability in mass loss rates points to factors capable of amplifying glacier recession in addition to climatic change along the Himalaya. Here we examine the influence of surface debris cover and glacial lakes on glacier mass loss across the Himalaya since the 1970s. We find no substantial difference in the mass loss of debris-covered and clean-ice glaciers over our study period, but substantially more negative (−0.13 to −0.29 m w.e.a−1) mass balances for lake-terminating glaciers, in comparison to land-terminating glaciers, with the largest differences occurring after 2000. Despite representing a minor portion of the total glacier population (~10%), the recession of lake-terminating glaciers accounted for up to 32% of mass loss in different sub-regions. The continued expansion of established glacial lakes, and the preconditioning of land-terminating glaciers for new lake development increases the likelihood of enhanced ice mass loss from the region in coming decades; a scenario not currently considered in regional ice mass loss projections.

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Improvements in XCO2 accuracy from OCO-2 with the latest ACOS v10 product

10.5194/egusphere-egu21-10484 ◽

2021 ◽

Author(s):

Christopher ODell ◽

Annmarie Eldering ◽

Michael Gunson ◽

David Crisp ◽

Brendan Fisher ◽

...

Keyword(s):

Power Plants ◽

Large Scale ◽

Regional Scale ◽

Surface Fluxes ◽

Retrieval Algorithm ◽

The Past ◽

Tropical Oceans ◽

Desert Areas ◽

Global Carbon

While initial plans for measuring carbon dioxide from space hoped for 1-2 ppm levels of accuracy (bias) and precision in the CO2 column mean dry air mole fraction (XCO2), in the past few years it has become clear that accuracies better than 0.5 ppm are required for most current science applications.&#160; These include measuring continental (1000+ km) and regional scale (100s of km) surface fluxes of CO2 at monthly-average timescales.&#160; Considering the 400+ ppm background, this translates to an accuracy of roughly 0.1%, an incredibly challenging target to hit.&#160;Improvements in both instrument calibration and retrieval algorithms have led to significant improvements in satellite XCO2 accuracies over the past decade.&#160; The Atmospheric Carbon Observations from Space (ACOS) retrieval algorithm, including post-retrieval filtering and bias correction, has demonstrated unprecedented accuracy with our latest algorithm version as applied to the Orbiting Carbon Observatory-2 (OCO-2) satellite sensor.&#160; &#160;This presentation will discuss the performance of the v10 XCO2 product by comparisons to TCCON and models, and showcase its performance with some recent examples, from the potential to infer large-scale fluxes to its performance on individual power plants.&#160; The v10 product yields better agreement with TCCON over land and ocean, plus reduced biases over tropical oceans and desert areas as compared to a median of multiple global carbon inversion models, allowing better accuracy and faith in inferred regional-scale fluxes. &#160;More specifically, OCO-2 has single sounding precision of ~0.8 ppm over land and ~0.5 ppm over water, and RMS biases of 0.5-0.7 ppm over both land and water.&#160; Given the six-year and growing length of the OCO-2 data record, this also enables new studies on carbon interannual variability, while at the same time allowing identification of more subtle and temporally-dependent errors.&#160; Finally, we will discuss the prospects of future improvements in the next planned version (v11), and the long-term prospects of greenhouse gas retrievals in the coming years.&#160;&#160;

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Local Sulphide Oxidation Drives Carbonate Dissolution in Modern Shallow Marine Carbonates: Evidence from Oxygen and Sulphur Isotope Composition of Pore Water Sulphate

Mineralogical Magazine ◽

10.1180/minmag.1998.62a.2.99 ◽

1998 ◽

Vol 62A (2) ◽

pp. 820-821

Author(s):

T. C. W. Ku

Keyword(s):

Pore Water ◽

Isotope Composition ◽

Carbonate Dissolution ◽

Sulphur Isotope ◽

Shallow Marine ◽

Sulphide Oxidation ◽

Sulphur Isotope Composition ◽

Marine Carbonates

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Browser based state-of-the-art software for automated data reduction, quality control and dissemination for marine carbon data

10.5194/egusphere-egu2020-20215 ◽

2020 ◽

Author(s):

Benjamin Pfeil ◽

Steve Jones ◽

Maren Karlsen ◽

Camilla Stegen Landa ◽

Rocio Castano Primo ◽

...

Keyword(s):

Quality Control ◽

Scientific Community ◽

Regional Scale ◽

Policy Decision ◽

Data Availability ◽

Observation System ◽

Time Data ◽

Representative Sampling ◽

Data Centres ◽

Global Carbon

Essential Ocean Variable Inorganic Carbon observations collected from instruments at sea are typically processed by individual PIs before submitting to data centres and other data archives. Often this work is done on an ad-hoc basis using unpublished, self-built software, and published in unique formats. This conflicts with the Interoperability and Reusability aspects of the FAIR data principles: such data requires significant reformatting efforts by data centres and/or end users, and reproducibility is impossible without a full record of the processing performed and QC decisions made by PIs. The manual nature of this process implies additional workload for PIs who need to submit their data to multiple archives/data product. There is a clear need to standardise the data workflow from measurement to publication using common, open source, and documented tools whose algorithms are fully accessible and all processing is recorded for full transparency.The Ocean Thematic Centre of the European Research Infrastructure ICOS (Integrated Carbon Observation System) is developing QuinCe, a browser-based tool for uploading, processing, automatic and manual quality control, and publication of data from underway pCO&#8322; systems on ships and moorings. Data can be uploaded directly from instruments in any text format, where it is standardised and processed using algorithms approved by the scientific community. Automatic QC algorithms can detect many obvious data errors; afterwards PIs can perform full quality control of the data following Standard Operating Procedures and best practises. All records of QC decisions, with enforced explanatory notes, are recorded by the software to enable full traceability and reproducibility. The final QCed dataset can be downloaded by the PI, and is sent to the ICOS Carbon Portal and SOCAT project for publication. The ICOS Carbon Portal integrates marine data with ICOS data from the ecosystem and atmosphere on a regional scale and data is integrated via SOCAT in the annual Global Carbon Budgets of the Global Carbon Project where it informs policy/decision makers, the scientific community and the general public.For platforms with operational data flows, the data is transmitted directly from ship to shore, QuinCe processes, quality controls and publishes Near Real Time data to the ICOS Carbon Portal and to Copernicus Marine Environmental Monitoring Services In Situ TAC as soon as it is received with no human intervention, greatly reducing the time from measurement to data availability.Full metadata records for instruments are kept and maintained at the ICOS Carbon Portal, utilising existing standardised vocabularies and version control to maintain a complete history. The correct metadata for any given dataset is available at any time, and can be converted to any required format, allowing compliance with the United Nations Sustainable Development Goal 14.3.1 methodology &#8216;average marine acidity (pH) measured at agreed suite of representative sampling stations&#8217; and ICOS data relevant to SDG 14.3 is distributed to IOC UNESCO&#8217;s IODE. While much of this work is currently performed manually, international efforts are underway to develop fully automated systems and these will be integrated as they become available.

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Study of regional geological structures in Ridi-Shantipur area of Gulmi district, Lesser Himalaya, west-central Nepal

Journal of Nepal Geological Society ◽

10.3126/jngs.v58i0.24594 ◽

2019 ◽

Vol 58 ◽

pp. 111-118

Author(s):

Shrawan Shakya ◽

Kabi Raj Paudyal

Keyword(s):

Regional Scale ◽

Lesser Himalaya ◽

The North ◽

Central Nepal ◽

West Central ◽

Continuous Shear ◽

Deformation Event ◽

Middle Member ◽

Geological Units ◽

The Himalaya

The study was carried out in the Lesser Himalaya between Ridi-Shantipur area of the Gulmi District, west-central Nepal. Two geological units: the Nourpul Formation and the Dhading Dolomite were mapped in the area. These units belong to the Nawakot Group as explained by several researchers in central Nepal. The Nourpul Formation can further be divided into three members based on distinct mappable lithology, which are named as the Lower Member, the Middle Member and the Upper Member, respectively. The area is highly folded with several local and regional anticlines and synclines; Ridi Khola Anticline, Ridi-Karikot Syncline, Ruru Anticline, Baletaksar-Gwadi Syncline, Huga-Bamgha Anticline, Rimuwa-Rudrabeni Syncline, Juhan-Eksing Anticline, Juniya-Limgha Syncline, Bharse-Thaple Anticline, and Chiureko Syncline, respectively from the south to the north. All the folds are trending along to the ESE-WNW direction. The origin of these folds can be linked with the thrust propagation in the Himalaya that can be explained with the deformation event D4. The Harewa Khola Thrust is the only one regional scale thrust mapped in the area. The thrust carries the older Nourpul Formation over the Dhading Dolomite with the indications of thrust related features like slickensides and fault-breccias. The thrust seems to propagate to the north. There is a continuous shear zone mapped in the outcrops from the Tal Khola-Aslewa-Eksingh-Gudrung-Juhang- Rupakot region as an indicator of the presence of the Badi Gad Fault in the region.

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Sulphide oxidation and carbonate dissolution as a source of CO2 over geological timescales

Nature ◽

10.1038/nature13030 ◽

2014 ◽

Vol 507 (7492) ◽

pp. 346-349 ◽

Cited By ~ 110

Author(s):

Mark A. Torres ◽

A. Joshua West ◽

Gaojun Li

Keyword(s):

Carbonate Dissolution ◽

Sulphide Oxidation

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Revisiting groundwater carbon fluxes to the ocean with implications for the carbon cycle

Geology ◽

10.1130/g46408.1 ◽

2019 ◽

Vol 48 (1) ◽

pp. 67-71 ◽

Cited By ~ 3

Author(s):

Shuang Zhang ◽

Noah J. Planavsky

Keyword(s):

United States ◽

Carbon Cycle ◽

Carbon Sink ◽

Groundwater Discharge ◽

Global Carbon Cycle ◽

The United States ◽

Silicate Weathering ◽

Fresh Groundwater ◽

Discharge Rates ◽

Global Carbon

Abstract Compared with riverine systems, the influence of groundwater on the global carbon cycle has remained underexplored. Here, we provide a new estimate of the bicarbonate fluxes from fresh groundwater to the ocean by coupling a statistical and hydrological analysis of groundwater and river samples across the contiguous United States with a study of global groundwater characteristics. We find that the mean concentration ([]) in groundwaters exceeds that in surface rivers by a factor of 2–3 throughout the contiguous United States. Based on estimates of fresh groundwater discharge to the ocean and scaling up our estimated mean [] in groundwaters from the United States and around the world, we arrived at a mean global flux from groundwaters ranging from 7.4 × 1012 (25th percentile)–1.8 × 1013 mol/yr (75th percentile) to 2.8 × 1013–8.3 × 1013 mol/yr, which is 22%–237% of the global flux from river systems, respectively. We also estimated that the global carbon flux derived from subsurface silicate weathering could be comparable to 32%–351% that from surficial silicate weathering, depending on groundwater discharge rates. Despite large uncertainties due to data limitation, this study highlights that groundwater weathering could be an important carbon sink in both the short- and long-term carbon cycle. Therefore, additional work on groundwaters is needed to develop a well-constrained view of the global carbon cycle.

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Regional Scale Mapping of Grassland Mowing Frequency with Sentinel-2 Time Series

Remote Sensing ◽

10.3390/rs10081221 ◽

2018 ◽

Vol 10 (8) ◽

pp. 1221 ◽

Cited By ~ 18

Author(s):

Natalia Kolecka ◽

Christian Ginzler ◽

Robert Pazur ◽

Bronwyn Price ◽

Peter Verburg

Keyword(s):

Time Series ◽

Regional Scale ◽

Remote Sensing Data ◽

Grassland Management ◽

Management Activity ◽

Field Campaigns ◽

Grass Growth ◽

Key Events ◽

Global Carbon ◽

Sentinel 2

Grassland use intensity is a topic of growing interest worldwide, as grasslands are integral in supporting biodiversity, food production, and regulating of the global carbon cycle. Data available for characterizing grasslands management are largely descriptive and collected from laborious field campaigns or questionnaires. The recent launch of the Sentinel-2 earth monitoring constellation provides new possibilities for high temporal and spatial resolution remote sensing data covering large areas. This study aims to evaluate the potential of a time series of Sentinel-2 data for mapping of mowing frequency in the region of Canton Aargau, Switzerland. We tested two cloud masking processes and three spatial mapping units (pixels, parcel polygons and shrunken parcel polygons), and investigated how missing data influence the ability to accurately detect and map grassland management activity. We found that more than 40% of the study area was mown before 15 June, while the remaining part was either mown later, or was not mown at all. The highest accuracy for detection of mowing events was achieved using additional clouds masking and size reduction of parcels, which allowed correct detection of 77% of mowing events. Additionally, we found that using only standard cloud masking leads to significant overestimation of mowing events, and that the detection based on sparse time series does not fully correspond to key events in the grass growth season.

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