Technical Note: Mesocosm approach to quantify dissolved inorganic carbon percolation fluxes

Thaysen, Eike Marie; Jessen, Søren; Beier, Claus; Postma, Dieke; Jakobsen, Iver

doi:10.5194/bg-11-1077-2014

Cited by 5 publications

(16 citation statements)

References 31 publications

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“…Vertical drainage of water through the soil, or small fluctuations in water table height over storm cycles, would work similarly in the wet season. This mechanism could transport soil‐source DIC and other soil gases into hyporheic water [ Williams and Oostrom , ; Thaysen et al ., ], and appears to be more effective in heterogeneous media than in homogenous media [ Haberer et al ., ]. We have not quantified these mechanisms, thus we do not know their importance to carbon fluxes in the WS1 hyporheic zone.…”

Section: Discussionmentioning

confidence: 99%

Carbon dynamics in the hyporheic zone of a headwater mountain stream in the Cascade Mountains, Oregon

et al. 2016

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We investigated carbon dynamics in the hyporheic zone of a steep, forested, headwater catchment western Oregon, USA. Water samples were collected monthly from the stream and a well network during base flow periods. We examined the potential for mixing of different source waters to explain concentrations of DOC and DIC. We did not find convincing evidence that either inputs of deep groundwater or lateral inputs of shallow soil water influenced carbon dynamics. Rather, carbon dynamics appeared to be controlled by local processes in the hyporheic zone and overlying riparian soils. DOC concentrations were low in stream water (0.04–0.09 mM), and decreased with nominal travel time through the hyporheic zone (0.02–0.04 mM lost over 100 h). Conversely, stream water DIC concentrations were much greater than DOC (0.35–0.7 mM) and increased with nominal travel time through the hyporheic zone (0.2–0.4 mM gained over 100 h). DOC in stream water could only account for 10% of the observed increase in DIC. In situ metabolic processing of buried particulate organic matter as well as advection of CO2 from the vadose zone likely accounted for the remaining 90% of the increase in DIC. Overall, the hyporheic zone was a source of DIC to the stream. We suggest that, in mountain stream networks, hyporheic exchange facilitates the transformation of particulate organic carbon buried in floodplains and transports the DIC that is produced back to the stream where it can be evaded to the atmosphere.

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Section: Discussionmentioning

confidence: 99%

Carbon dynamics in the hyporheic zone of a headwater mountain stream in the Cascade Mountains, Oregon

et al. 2016

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“…5a) that was most pronounced when waterlogging (Supplement Fig. S2) was highest (Thaysen et al, 2014a). The simulated evolution of alkalinity and pH over time was satisfactory in terms of magnitude and peak depth, but the steep decline in the C horizon alkalinity and pH could not be captured (Fig.…”

Section: Resultsmentioning

confidence: 99%

Effects of Lime and Concrete Waste on Vadose Zone Carbon Cycling

Thaysen

Jessen²,

Postma

et al. 2014

Vadose Zone Journal

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In a series of mesocosm experiments, with barley (Hordeum vulgare L.) grown on podzolic soil material, we have investigated inorganic carbon cycling through the gaseous and liquid phases and how it is affected by different soil amendments. The mesocosm amendments comprised the addition of 0, 9.6, or 21.2 kg m −2 of crushed concrete waste (CCW) or 1 kg lime m −2 . The CCW and lime treatments increased the dissolved inorganic carbon (DIC) percolation flux by about 150 and 100%, respectively, compared to the controls. However, concurrent increases in the CO 2 efflux to the atmosphere (ER) were more than one order of magnitude higher than increases in the DIC percolation flux. Analysis of soil solutions, coupled reactive-transport modeling studies, and a decrease in soil carbonate contents over the experiment altogether suggested that the increased ER from amended mesocosms was derived from the carbonate contained in the amendments, which, hence, mostly escaped to the atmosphere. Our results are important in the context of climate change due to the widespread application of lime to acidic soils. The CCW amendment had no adverse effects on plant growth and groundwater quality.

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“…In this study, seven mesocosms were constructed and incubated in a climate chamber. A detailed description of the experimental set-up and filling of mesocosms is given in Thaysen et al (2014a). Soil was collected from the A and C horizon of an experimental field site located in an agricultural area (Voulund, Denmark, 56 • 2 35.7 N, 9 • 8 101.1 E) characterized as a coarse-sandy alluvial sediment (Podzol).…”

Section: Setup Of Mesocosmsmentioning

confidence: 99%

“…In addition, the [DIC] depends on soil solution chemistry because of the pH-dependent solubility of inorganic C species, and is as such largely influenced by processes that increase soil alkalinity, e.g., the weathering of carbonate and silicate minerals (Appelo and Postma, 2005;Walmsley et al, 2011). The DIC percolation flux to the groundwater can be described by multiplying the [DIC] by the recharge flux (Appelo and Postma, 2005;Thaysen et al, 2014a).…”

Section: Introductionmentioning

confidence: 99%

“…The mesocosms, established to simulate the top 0-80 cm soil profile of a barley cropland, were incubated under controlled environmental conditions, allowing a modelbased investigation (HP1 module, Hydrus 1-D) of the biogeochemical controls on CO 2 production and transport in the soil profile prior to seeding, during growth and after harvest. Mesocosms have been shown to provide useful environments for conducting process-related research in unsaturated soil (Hendry et al, 2001;Thaysen et al, 2014a). Reactive transport modeling may further increase the understanding of the coupled physical, chemical, and biological processes influencing CO 2 transport within soils (Steefel et al, 2005).…”

Section: Introductionmentioning

confidence: 99%

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Inorganic carbon fluxes across the vadose zone of planted and unplanted soil mesocosms

et al. 2014

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Abstract. The efflux of carbon dioxide (CO2) from soils influences atmospheric CO2 concentrations and thereby climate change. The partitioning of inorganic carbon (C) fluxes in the vadose zone between emission to the atmosphere and to the groundwater was investigated to reveal controlling underlying mechanisms. Carbon dioxide partial pressure in the soil gas (pCO2), alkalinity, soil moisture and temperature were measured over depth and time in unplanted and planted (barley) mesocosms. The dissolved inorganic carbon (DIC) percolation flux was calculated from the pCO2, alkalinity and the water flux at the mesocosm bottom. Carbon dioxide exchange between the soil surface and the atmosphere was measured at regular intervals. The soil diffusivity was determined from soil radon-222 (222Rn) emanation rates and soil air Rn concentration profiles and was used in conjunction with measured pCO2 gradients to calculate the soil CO2 production. Carbon dioxide fluxes were modeled using the HP1 module of the Hydrus 1-D software. The average CO2 effluxes to the atmosphere from unplanted and planted mesocosm ecosystems during 78 days of experiment were 0.1 ± 0.07 and 4.9 ± 0.07 μmol C m−2 s−1, respectively, and grossly exceeded the corresponding DIC percolation fluxes of 0.01 ± 0.004 and 0.06 ± 0.03 μmol C m−2 s−1. Plant biomass was high in the mesocosms as compared to a standard field situation. Post-harvest soil respiration (Rs) was only 10% of the Rs during plant growth, while the post-harvest DIC percolation flux was more than one-third of the flux during growth. The Rs was controlled by production and diffusivity of CO2 in the soil. The DIC percolation flux was largely controlled by the pCO2 and the drainage flux due to low solution pH. Modeling suggested that increasing soil alkalinity during plant growth was due to nutrient buffering during root nitrate uptake.

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Technical Note: Mesocosm approach to quantify dissolved inorganic carbon percolation fluxes

Cited by 5 publications

References 31 publications

Carbon dynamics in the hyporheic zone of a headwater mountain stream in the Cascade Mountains, Oregon

Carbon dynamics in the hyporheic zone of a headwater mountain stream in the Cascade Mountains, Oregon

Effects of Lime and Concrete Waste on Vadose Zone Carbon Cycling

Inorganic carbon fluxes across the vadose zone of planted and unplanted soil mesocosms

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