CO2 and H2SO4 consumption in weathering and material transport to the ocean, and their role in the global carbon balance

Lerman, Abraham; Wu, Lingling; Mackenzie, Fred T.

doi:10.1016/j.marchem.2006.04.004

Cited by 164 publications

(103 citation statements)

References 53 publications

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“…(10) and with calculated values for δ 13 C Cal,PI and δ 13 C OrgC,PI of 1.15 and −23.17‰, respectively, we find that 25.3% and 74.7% of the lithosphere outgassing derives from old organic carbon and carbonate, respectively. The model estimate for total river inflow of inorganic carbon, R C,PI (=2(W Carb,PI +W Sil,PI )=2B Cal,PI ), is 0.40 Gt C yr −1 , in agreement with recent, data-based estimates (Lerman et al, 2007).…”

Section: Bioturbated Sediment Layer Distributionssupporting

confidence: 83%

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Presentation, calibration and validation of the low-order, DCESS Earth System Model (Version 1)

2008

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Abstract.A new, low-order Earth System Model is described, calibrated and tested against Earth system data. The model features modules for the atmosphere, ocean, ocean sediment, land biosphere and lithosphere and has been designed to simulate global change on time scales of years to millions of years. The atmosphere module considers radiation balance, meridional transport of heat and water vapor between low-mid latitude and high latitude zones, heat and gas exchange with the ocean and sea ice and snow cover. Gases considered are carbon dioxide and methane for all three carbon isotopes, nitrous oxide and oxygen. The ocean module has 100 m vertical resolution, carbonate chemistry and prescribed circulation and mixing. Ocean biogeochemical tracers are phosphate, dissolved oxygen, dissolved inorganic carbon for all three carbon isotopes and alkalinity. Biogenic production of particulate organic matter in the ocean surface layer depends on phosphate availability but with lower efficiency in the high latitude zone, as determined by model fit to ocean data. The calcite to organic carbon rain ratio depends on surface layer temperature. The semi-analytical, ocean sediment module considers calcium carbonate dissolution and oxic and anoxic organic matter remineralisation. The sediment is composed of calcite, non-calcite mineral and reactive organic matter. Sediment porosity profiles are related to sediment composition and a bioturbated layer of 0.1 m thickness is assumed. A sediment segment is ascribed to each ocean layer and segment area stems from observed ocean depth distributions. Sediment burial is calculated from Correspondence to: G. Shaffer (gs@dcess.ku.dk) sedimentation velocities at the base of the bioturbated layer. Bioturbation rates and oxic and anoxic remineralisation rates depend on organic carbon rain rates and dissolved oxygen concentrations. The land biosphere module considers leaves, wood, litter and soil. Net primary production depends on atmospheric carbon dioxide concentration and remineralization rates in the litter and soil are related to mean atmospheric temperatures. Methane production is a small fraction of the soil remineralization. The lithosphere module considers outgassing, weathering of carbonate and silicate rocks and weathering of rocks containing old organic carbon and phosphorus. Weathering rates are related to mean atmospheric temperatures.A pre-industrial, steady state calibration to Earth system data is carried out. Ocean observations of temperature, carbon 14, phosphate, dissolved oxygen, dissolved inorganic carbon and alkalinity constrain air-sea exchange and ocean circulation, mixing and biogeochemical parameters. Observed calcite and organic carbon distributions and inventories in the ocean sediment help constrain sediment module parameters. Carbon isotopic data and carbonate vs. silicate weathering fractions are used to estimate initial lithosphere outgassing and rock weathering rates. Model performance is tested by simulating atmospheric greenhouse gas increases, global warming ...

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Section: Bioturbated Sediment Layer Distributionssupporting

confidence: 83%

“…From a detailed study of global weathering sources, we take γ Sil =0.85 (Lerman et al, 2007). An analogous, steady state equation for 13 C may be written as…”

Section: Rock Weathering Volcanism and River Inputmentioning

confidence: 99%

Presentation, calibration and validation of the low-order, DCESS Earth System Model (Version 1)

2008

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“…366 Lerman et al, 2007). In this study, temperature could not be established as a dominant controlling 367 factor, probably due to the properties of the applied training catchments and because it was found that 368 temperature information is partly represented by the applied runoff data (see for further discussion: 369…”

Section: ) 238mentioning

confidence: 85%

Global CO2-consumption by chemical weathering: What is the contribution of highly active weathering regions?

Hartmann

Jansen

Dürr

et al. 2009

Global and Planetary Change

290

255

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10 CO 2 -consumption by chemical weathering of silicates and resulting silicate/carbonate weathering 11 ratios influences long-term climate changes. However, little is known of the spatial extension of highly 12 active weathering regions and their proportion of global CO 2 -consumption. As those regions may be of 13 significant importance for global climate change, global CO 2 -consumption is calculated here at high 14 resolution, to adequately represent them. In previous studies global CO 2 -consumption is estimated 15 using two different approaches: i) a reverse approach based on hydrochemical fluxes from large rivers 16and ii) a forward approach applying spatially explicit a function for CO 2 -consumption. The first 17 approach results in an estimate without providing a spatial resolution for highly active regions and the 18 second approach applied six lithological classes while including three sediment classes (shale, 19 sandstone and carbonate rock) based at a 1°or 2°grid resolution. It remained uncertain, if the applied 20 lithological classification schemes represent adequately CO 2 -consumption from sediments on a global 21 scale. This is due to the large variability of sediment properties, their diagenetic history and the 22 contribution from carbonates apparent in silicate dominated lithological classes. To address these 23 issues, a CO 2 -consumption model, trained at high resolution data, is applied here to a global vector 24 based lithological map with 15 lithological classes. The calibration data were obtained from areas 25 representing a wide range of weathering rates. Resulting global CO 2 -consumption by chemical 26 weathering is similar to earlier estimates (237 Mt C a -1 ) but the proportion of silicate weathering is 27 63%, and thus larger than previous estimates (49 to 60%). The application of the enhanced lithological 28 classification scheme reveals that it is important to distinguish among the various types of sedimentary 29 rocks and their diagenetic history to evaluate the spatial distribution of rock weathering. Results 30 highlight the role of hotspots (> 10 times global average weathering rates) and hyperactive areas (5 to 31 10 times global average rates). Only 9 % of the global exorheic area is responsible for about 50 % of 32 CO 2 -consumption by chemical weathering (or if hotspots and hyperactive areas are considered: 3.4% 33 of exorheic surface area corresponds to 28% of global CO 2 -consumption). The contribution of 34 endorheic areas to the global CO 2 -consumption is with 3.7 Mt C a -1 only minor. A significant impact on 35 * Manuscript Click here to view linked References 2 the global CO 2 -consumption rate can be expected if identified highly active areas are affected by 36 changes in the overall spatial patterns of the hydrological cycle due to ongoing global climate change. 37Specifically if comparing the Last Glacial Maximum with present conditions it is probable that also the 38 global carbon cycle has been affected by those changes. It is expected that results...

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“…CaCO 3 þ H 2 SO 4 ! Ca 2þ þ H 2 O þ CO 2 þ SO 2À 4 ) does not consume contemporary atmospheric CO 2 (Lerman et al, 2007). Only half of the DIC released by the weathering of carbonates via CO 2 -carbonic acid is older C, whereas all of the DIC released by H 2 SO 4 weathering is older C. Therefore, H 2 SO 4 -induced weathering is expected to result in a higher net release of stored C relative to carbonic-acid driven weathering.…”

Section: Introductionmentioning

confidence: 99%

Isotopic evidence of enhanced carbonate dissolution at a coal mine drainage site in Allegheny County, Pennsylvania, USA

Sharma

Sack

Adams

et al. 2013

Applied Geochemistry

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Editorial handling by A. Kolker a b s t r a c t Stable isotopes were used to determine the sources and fate of dissolved inorganic C (DIC) in the circumneutral pH drainage from an abandoned bituminous coal mine in western Pennsylvania. The C isotope signatures of DIC (d 13 C DIC ) were intermediate between local carbonate and organic C sources, but were higher than those of contemporaneous Pennsylvanian age groundwaters in the region. This suggests a significant contribution of C enriched in 13 C due to enhanced carbonate dissolution associated with the release of H 2 SO 4 from pyrite oxidation. The Sr isotopic signature of the drainage was similar to other regional mine waters associated with the same coal seam and reflected contributions from limestone dissolution and cation exchange with clay minerals. The relatively high d 34 S SO4 and d 18 O SO4 isotopic signatures of the mine drainage and the presence of presumptive SO 4 -reducing bacteria suggest that SO 4 reduction activity also contributes C depleted in 13 C isotope to the total DIC pool. With distance downstream from the mine portal, C isotope signatures in the drainage increased , accompanied by decreased total DIC concentrations and increased pH. These data are consistent with H 2 SO 4 dissolution of carbonate rocks, enhanced by cation exchange, and C release to the atmosphere via CO 2 outgassing.

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CO2 and H2SO4 consumption in weathering and material transport to the ocean, and their role in the global carbon balance

Cited by 164 publications

References 53 publications

Presentation, calibration and validation of the low-order, DCESS Earth System Model (Version 1)

Presentation, calibration and validation of the low-order, DCESS Earth System Model (Version 1)

Global CO2-consumption by chemical weathering: What is the contribution of highly active weathering regions?

Isotopic evidence of enhanced carbonate dissolution at a coal mine drainage site in Allegheny County, Pennsylvania, USA

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