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

2014 ◽  
Vol 11 (24) ◽  
pp. 7179-7192 ◽  
Author(s):  
E. M. Thaysen ◽  
D. Jacques ◽  
S. Jessen ◽  
C. E. Andersen ◽  
E. Laloy ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Plant Growth ◽  
Vadose Zone ◽  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Carbon Dioxide Partial Pressure ◽  
Co2 Production ◽  
Post Harvest ◽  
Unplanted Soil ◽  
Soil Mesocosms

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.

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

2014 ◽  
Vol 11 (3) ◽  
pp. 4251-4299 ◽  
Author(s):  
E. M. Thaysen ◽  
D. Jacques ◽  
S. Jessen ◽  
C. E. Andersen ◽  
E. Laloy ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Vadose Zone ◽  
Inorganic Carbon ◽  
Plant Biomass ◽  
Dissolved Inorganic Carbon ◽  
Carbon Fluxes ◽  
Atmospheric Co2 ◽  
Carbon Dioxide Partial Pressure ◽  
Post Harvest ◽  
Unplanted Soil

Abstract. The efflux of carbon dioxide (CO2) from soils influences atmospheric CO2 concentrations and thereby climate change. The partitioning of inorganic carbon fluxes in the vadose zone between emission to the atmosphere and to the groundwater was investigated. 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 modelled 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 carbon (C) m−2 s−1, respectively, and largely exceeded the corresponding DIC percolation fluxes of 0.01 ± 0.004 and 0.06 ± 0.03 μmol C m−2 s−1. 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. Plant biomass and soil pCO2 were high in the mesocosms as compared to a standard field situation. Our results indicate no change of the cropland C balance under elevated atmospheric CO2 in a warmer future climate, in which plant biomass and soil pCO2 are expected to increase.

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

2014 ◽  
Vol 11 (4) ◽  
pp. 1077-1084 ◽  
Author(s):  
E. M. Thaysen ◽  
S. Jessen ◽  
P. Ambus ◽  
C. Beier ◽  
D. Postma ◽  
...  
Keyword(s):  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Experimental Period ◽  
Technical Note ◽  
Transport Processes ◽  
Carbon Dioxide Partial Pressure ◽  
Physical Factors ◽  
Soil Carbon Dioxide ◽  
Promising Tool ◽  
Unplanted Soil

Abstract. Dissolved inorganic carbon (DIC) fluxes across the vadose zone are influenced by a complex interplay of biological, chemical and physical factors. A novel soil mesocosm system was evaluated as a tool for providing information on the mechanisms behind DIC percolation to the groundwater from unplanted soil. Carbon dioxide partial pressure (pCO2), alkalinity, soil moisture and temperature were measured with depth and time, and DIC in the percolate was quantified using a sodium hydroxide trap. Results showed good reproducibility between two replicate mesocosms. The pCO2 varied between 0.2 and 1.1%, and the alkalinity was 0.1–0.6 meq L−1. The measured cumulative effluent DIC flux over the 78-day experimental period was 185–196 mg L−1 m−2 and in the same range as estimates derived from pCO2 and alkalinity in samples extracted from the side of the mesocosm column and the drainage flux. Our results indicate that the mesocosm system is a promising tool for studying DIC percolation fluxes and other biogeochemical transport processes in unsaturated environments.

scholarly journals Impact of peatlands on carbon dioxide (CO<sub>2</sub>) emissions from the Rajang River and Estuary, Malaysia

2018 ◽  
Author(s):  
Denise Müller-Dum ◽  
Thorsten Warneke ◽  
Tim Rixen ◽  
Moritz Müller ◽  
Antje Baum ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Co2 Flux ◽  
Southeast Asian ◽  
Dry Season ◽  
Carbon Dioxide Partial Pressure ◽  
Wet Season ◽  
Peat Deposits ◽  
Carbon Dioxide Co2

Abstract. Tropical peat-draining rivers are known as potentially large sources of carbon dioxide (CO2) to the atmosphere due to high loads of carbon they receive from surrounding soils. However, not many seasonally resolved data are available, limiting our understanding of these systems. We report the first measurements of carbon dioxide partial pressure (pCO2) in the Rajang River and Estuary, the longest river in Malaysia. The Rajang River catchment is characterized by extensive peat deposits found in the delta region, and by human impact such as logging, land use and river damming. pCO2 averaged 2919 ± 573 µatm during the wet season and 2732 ± 443 µatm during the dry season. This is at the low end of reported values for Southeast Asian peat-draining rivers, but higher than values reported for Southeast Asian rivers that do not flow through peat deposits. However, dissolved inorganic carbon (DIC) and δ13C-DIC data did not suggest that peatlands were an important source of inorganic carbon to the river, with an average DIC concentration of 203.9 ± 59.6 µmol L−1 and an average δ13C-DIC of −8.06 ± 1.90 ‰. Also, compared to rivers with similar peat coverage, the pCO2 in the Rajang was rather low. Thus, we suggest that peat coverage is, by itself, insufficient as sole predictor of CO2 emissions from peat-draining rivers, and that other factors, like the spatial distribution of peat in the catchment and pH, need to be considered as well. In the Rajang River, peatlands probably do not contribute much to the CO2 flux due to the proximity of the peatlands to the coast. CO2 fluxes to the atmosphere were 2.28 ± 0.52 gC m−2 d−1 (wet season) and 2.45 ± 0.45 gC m−2 d−1 (dry season), making the Rajang River a moderate source of carbon to the atmosphere.

scholarly journals Impact of seawater <i>p</i>CO<sub>2</sub> on calcification and Mg/Ca and Sr/Ca ratios in benthic foraminifera calcite: results from culturing experiments with <i>Ammonia tepida</i>

2010 ◽  
Vol 7 (1) ◽  
pp. 81-93 ◽  
Author(s):  
D. Dissard ◽  
G. Nehrke ◽  
G. J. Reichart ◽  
J. Bijma
Keyword(s):  
Carbon Dioxide ◽  
Calcium Carbonate ◽  
Benthic Foraminifera ◽  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Planktonic Foraminifera ◽  
Ambient Conditions ◽  
Precipitated Calcium Carbonate ◽  
Shell Weight ◽  
Dissolved Carbon

Abstract. Evidence of increasing concentrations of dissolved carbon dioxide, especially in the surface ocean and its associated impacts on calcifying organisms, is accumulating. Among these organisms, benthic and planktonic foraminifera are responsible for a large amount of the globally precipitated calcium carbonate. Hence, their response to an acidifying ocean may have important consequences for future inorganic carbon cycling. To assess the sensitivity of benthic foraminifera to changing carbon dioxide levels and subsequent alteration in seawater carbonate chemistry, we cultured specimens of the shallow water species Ammonia tepida at two concentrations of atmospheric CO2 (230 and 1900 ppmv) and two temperatures (10 °C and 15 °C). Shell weights and elemental compositions were determined. Impact of high and low pCO2 on elemental composition are compared with results of a previous experiment were specimens were grown under ambient conditions (380 ppvm, no shell weight measurements of specimen grown under ambient conditions are, however, available). Results indicate that shell weights decrease with decreasing [CO32−], although calcification was observed even in the presence of calcium carbonate under-saturation, and also decrease with increasing temperature. Thus both warming and ocean acidification may act to decrease shell weights in the future. Changes in [CO32−] or total dissolved inorganic carbon do not affect the Mg distribution coefficient. On the contrary, Sr incorporation is enhanced under increasing [CO32−]. Implications of these results for the paleoceanographic application of foraminifera are discussed.

scholarly journals Impact of seawater <i>p</i>CO<sub>2</sub> changes on calcification and on Mg/Ca and Sr/Ca in benthic foraminifera calcite (<i>Ammonia tepida</i>): results from culturing experiments

2009 ◽  
Vol 6 (2) ◽  
pp. 3771-3802 ◽  
Author(s):  
D. Dissard ◽  
G. Nehrke ◽  
G. J. Reichart ◽  
J. Bijma
Keyword(s):  
Carbon Dioxide ◽  
Benthic Foraminifera ◽  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Planktonic Foraminifera ◽  
Precipitated Calcium Carbonate ◽  
Dissolved Carbon ◽  
Seawater Carbonate Chemistry ◽  
Carbon Dioxide Levels ◽  
Shallow Water Species

Abstract. Evidence is accumulating of increasing concentrations of dissolved carbon dioxide in the ocean and associated acidification impacts on calcifying organisms. Among these organisms, benthic and planktonic foraminifera are responsible for a large amount of the globally precipitated calcium carbonate. Therefore, their response to an acidifying ocean may have important consequences for future inorganic carbon cycling. To assess the sensitivity of benthic foraminifera to changing carbon dioxide levels and subsequent alteration in seawater carbonate chemistry, we cultured specimens of the shallow water species Ammonia tepida at two concentrations of atmospheric CO2 (120 and 2000 ppm) and two temperatures (10°C and 15°C). Shell weights and elemental compositions were determined. Results indicate that shell weights decrease with decreasing [CO32−], and increase with decreasing temperature. Changes in [CO32−] or total dissolved inorganic carbon do not affect the Mg partition coefficient. On the contrary, Sr incorporation is enhanced under increasing [CO32−]. Implications of these results for the paleoceanographic application of foraminifera are also discussed.

scholarly journals METABOLISMO LÍQUIDO DA MATÉRIA ORGÂNICA, CALCIFICAÇÃO E FLUXOS DE DIÓXIDO DE CARBONO EM DOIS RECIFES COSTEIROS SUJEITOS A DIFERENTES GRAUS DE IMPACTO: COROA VERMELHA E TAIPÚS DE FORA, BAHIA

2016 ◽  
Vol 19 (3) ◽  
Author(s):  
Marcelo Friederichs Landim de Souza ◽  
Thaís Bomfim Santana
Keyword(s):  
Carbon Dioxide ◽  
Partial Pressure ◽  
Atmospheric Carbon Dioxide ◽  
Reef Flat ◽  
Dissolved Inorganic Carbon ◽  
Total Alkalinity ◽  
Carbon Dioxide Partial Pressure ◽  
Saturation State ◽  
Anthropogenic Inputs ◽  
Thermodynamic Conditions

This study intended to compare physical and chemical variables, net ecosystem metabolism (production – respiration) and calcification-carbonate dissolution rates in two coastal reefs subject to different levels of anthropogenic inputs of nutrients and organic matter. The coast surrounding Coroa Vermelha reef presented a higher degree of urbanization and touristic activities than Taipus de Fora at the time of sampling. The temperature, dissolved inorganic nutrients, total alkalinity, and total suspended solids were significantly higher in Coroa Vermelha reef, probably as a result of the anthropogenic inputs. These variables in Taipus de Fora were comparable to those found in the literature for Recife de Fora, an offshore protected reef and other less impacted reefs.  Total alkalinity, dissolved inorganic carbon and carbon dioxide partial pressure were lower and pH was higher in the reef flat than at the surrounding seawater. There was a prevalence of an influx of atmospheric carbon dioxide to reef water, net autotrophy and calcification. A significant correlation was observed between net calcification and net community metabolism. The benthic photosynthesis in the reef flat during low tide decreases the carbon dioxide partial pressure and increases the aragonite saturation state, establishing thermodynamic conditions that favor calcification.   

scholarly journals Technical note: mesocosm approach to quantification of carbon dioxide fluxes across the vadose zone

2013 ◽  
Vol 10 (6) ◽  
pp. 9947-9967
Author(s):  
E. M. Thaysen ◽  
S. Jessen ◽  
P. Ambus ◽  
C. Beier ◽  
D. Postma ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Vadose Zone ◽  
Water Flux ◽  
Lower Boundary ◽  
Agricultural Practices ◽  
Small Variation ◽  
Technical Note ◽  
Carbon Dioxide Partial Pressure ◽  
Physical Factors ◽  
Promising Tool

Abstract. Carbon dioxide (CO2) fluxes in the vadose zone are influenced by a complex interplay of biological, chemical and physical factors. A soil mesocosm system was designed to assess the effect of agricultural practices on carbon fluxes within and out of the vadose zone at controlled environmental conditions. Carbon dioxide partial pressure (pCO2), alkalinity, soil moisture and temperature were measured with depth and time, and DIC in the percolate was quantified using a sodium hydroxide trap. Results showed good reproducibility between two replicate mesocosms. The pCO2 varied between 0.2–1.1% and alkalinity was 0.1–0.6 meq L−1. The measured effluent DIC flux was 185–196 mg L−1 m−2 and in the same range as estimates derived from pCO2 and alkalinity in samples extracted from the side of the mesocosm column, and the water flux. The relatively small variation provides confidence that the mesocosm system is a promising tool for studying a~range of processes in unsaturated environments. Meanwhile, high suction at the mesocosm bottom applied to reduce water ponding during intensive irrigation caused degassing of dissolved CO2 from the water phase just below the outlet, leading to diffusion of dissolved CO2 across the lower boundary. Though not influencing DIC flux measurements to the groundwater, this lead to a lowering of the pCO2 in the stagnant water at the mesocosm bottom. A free-drainage boundary is suggested in order to avoid this effect.

scholarly journals CO<sub>2</sub> perturbation experiments: similarities and differences between dissolved inorganic carbon and total alkalinity manipulations

2009 ◽  
Vol 6 (2) ◽  
pp. 4441-4462 ◽  
Author(s):  
K. G. Schulz ◽  
J. Barcelos e Ramos ◽  
R. E. Zeebe ◽  
U. Riebesell
Keyword(s):  
Carbon Dioxide ◽  
Atmospheric Carbon Dioxide ◽  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Total Alkalinity ◽  
Carbonate Chemistry ◽  
Surface Ocean ◽  
Seawater Carbonate Chemistry ◽  
Similarities And Differences ◽  
Carbon Dioxide Co2

Abstract. Increasing atmospheric carbon dioxide (CO2) through human activities and invasion of anthropogenic CO2 into the surface ocean alters the seawater carbonate chemistry, increasing CO2 and bicarbonate (HCO3

Anaerobic degradation of 2,4,6-trinitrotoluene in granular activated carbon fluidized bed and batch reactors

2001 ◽  
Vol 43 (1) ◽  
pp. 67-75 ◽  
Author(s):  
M. A. Moteleb ◽  
M. T. Suoidan ◽  
J. Kim ◽  
J. L. Davel ◽  
N. R. Adrian
Keyword(s):  
Carbon Dioxide ◽  
Activated Carbon ◽  
Fluidized Bed ◽  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Granular Activated Carbon ◽  
Batch Reactors ◽  
Serum Bottle ◽  
Degradation Rates ◽  
Water Waste

In this study, an anaerobic fluidized bed reactor (AFBR) was used to treat a synthetically produced pink water waste stream containing trinitrotoluene (TNT). The synthesized waste consisted of 95 mg/l-TNT, the main contaminant in pink water, which was to be co-metabolized with 560-mg/l ethanol. Granular activated carbon was used as the attachment medium for biological growth. TNT was reduced to a variety of compounds, mainly 2,4,6-triaminotoluene (2,4,6-TAT), 2,4-diamino-6-nitrotoluene (2,4-DA-6-NT), 2,6-diamino-4-nitrotoluene (2,6-DA-4-NT), 2-amino-4,6-dinitrotoluene (2-A-4,6-DNT), and 4-amino-2, 6-dinitrotoluene (4-A-2,6-DNT). These conversions resulted through the oxidation of ethanol to carbon dioxide under anoxic conditions, or reduction to methane under methanogenic conditions. The anaerobic reactor was charged with 1.0 kg of 16×20 U.S. Mesh Granular Activated Carbon (GAC) and was pre-loaded with 200g of TNT prior to the addition of the mixed seed culture. During the first three weeks of operation, ethanol was completely degraded and no methane was produced. Effluent inorganic carbon revealed stoichiometric conversion of the feed ethanol to dissolved inorganic carbon with accumulation of carbon dioxide in the headspace of the reactor. GAC extraction showed incremental reduction of the nitro groups to amino groups, with 2,4,6-TAT as the final product. After three weeks, the oxygen from the nitro groups was depleted and methane production commenced. The reproducibility of this phenomenon was confirmed by repeating the experiment in the same manner using an identical AFBR. Furthermore, serum bottle tests were conducted using TNT loading ratios of 0.2, 0.4, 0.8, 1.0 g-TNT/g-GAC as well as experiments in the absence of GAC. Similar behavior to that of the columns was observed, with degradation rates varying according to the particular condition. GAC greatly enhanced the degradation rates and the higher TNT loading resulted in slower degradation rates of ethanol.

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