scholarly journals Estimating the Surface Area of Small Rivers in the Southwestern Amazon and Their Role in CO2 Outgassing

2008 ◽  
Vol 12 (6) ◽  
pp. 1-16 ◽  
Author(s):  
Maria de Fátima F. L. Rasera ◽  
Maria Victoria R. Ballester ◽  
Alex V. Krusche ◽  
Cleber Salimon ◽  
Letícia A. Montebelo ◽  
...  
Keyword(s):  
Gas Exchange ◽  
Surface Area ◽  
River Basin ◽  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
River Network ◽  
Small Rivers ◽  
Amazon River ◽  
Carbon Export ◽  
Recent Estimate

Abstract A recent estimate of CO2 outgassing from Amazonian wetlands suggests that an order of magnitude more CO2 leaves rivers through gas exchange with the atmosphere than is exported to the ocean as organic plus inorganic carbon. However, the contribution of smaller rivers is still poorly understood, mainly because of limitations in mapping their spatial extent. Considering that the largest extension of the Amazon River network is composed of small rivers, the authors’ objective was to elucidate their role in air–water CO2 exchange by developing a geographic information system (GIS)-based model to calculate the surface area covered by rivers with channels less than 100 m wide, combined with estimated CO2 outgassing rates at the Ji-Paraná River basin, in the western Amazon. Estimated CO2 outgassing was the main carbon export pathway for this river basin, totaling 289 Gg C yr−1, about 2.4 times the amount of carbon exported as dissolved inorganic carbon (121 Gg C yr−1) and 1.6 times the dissolved organic carbon export (185 Gg C yr−1). The relationships established here between drainage area and channel width provide a new model for determining small river surface area, allowing regional extrapolations of air–water gas exchange. Applying this model to the entire Amazon River network of channels less than 100 m wide (third to fifth order), the authors calculate that the surface area of small rivers is 0.3 ± 0.05 million km2, and it is potentially evading to the atmosphere 170 ± 42 Tg C yr−1 as CO2. Therefore, these ecosystems play an important role in the regional carbon balance.

Dissolved Inorganic Carbon Export Across the Soil/Stream Interface and Its Fate in a Boreal Headwater Stream

2009 ◽  
Vol 43 (19) ◽  
pp. 7364-7369 ◽  
Author(s):  
Mats G. Öquist ◽  
Marcus Wallin ◽  
Jan Seibert ◽  
Kevin Bishop ◽  
Hjalmar Laudon
Keyword(s):  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Headwater Stream ◽  
Carbon Export ◽  
Stream Interface

Gas Exchange, Photosynthetic Uptake, and Carbon Budget for a Radiocarbon Addition to a Small Enclosure in a Stratified Lake

1980 ◽  
Vol 37 (3) ◽  
pp. 464-471 ◽  
Author(s):  
Peter Bower ◽  
Daniel McCorkle
Keyword(s):  
Mass Transfer ◽  
Gas Exchange ◽  
Primary Productivity ◽  
Carbon Budget ◽  
Inorganic Carbon ◽  
Net Primary Productivity ◽  
Dissolved Inorganic Carbon ◽  
Dark Respiration ◽  
Late Summer ◽  
Transfer Coefficients

9250 kBq (250 μCi) of 14C as NaHCO3 were added to the mixed-layer waters inside a long, cylindrical plastic enclosure anchored in an oligotrophic lake of the Canadian Shield. Loss of 14C from the epilimnion was predominantly in the form of irreversible gas-exchange across the liquid–air interface. This loss was measured by 14C inventory of the epilimnion and thermocline waters. Using the Lewis and Whitman boundary layer model, values for the mass transfer coefficient of 126, 58, and 100 cm/d were determined for three distinct phases in the deepening of the epilimnion during autumn cooling. The relationship between these mass transfer coefficients and the average wind speeds over the same three time periods were consistent with the results of previous wind-tunnel, gas-exchange experiments.Two significant features of the carbon budget during the course of the experiment were the large net outflux of CO2 from the corral (with [Formula: see text] in the epilimnion 3–7 times atmospheric levels) and the doubling of the total dissolved inorganic carbon (DIC) content of the epilimnion. The major source of carbon for these two processes was the entrainment of dissolved inorganic carbon as the epilimnion deepened during the cool days of late summer. Particulate organic carbon was also entrained and its oxidation contributed to the net DIC increase and CO2 loss. Simultaneous determinations of daily integral primary productivity by an incubator technique and by direct measurement of 14C uptake inside the enclosure were consistent. Dark respiration was 45–53% of daily integral primary productivity, but total respiration was nearly two times that for dark plus light respiration. Net primary productivity was thus substantially negative.Key words: Gas exchange, photosynthetic uptake, carbon budget

Whole-Lake Radiocarbon Experiment in an Oligotrophic Lake at the Experimental Lakes Area, Northwestern Ontario

1980 ◽  
Vol 37 (3) ◽  
pp. 454-463 ◽  
Author(s):  
R. H. Hesslein ◽  
W. S. Broecker ◽  
P. D. Quay ◽  
D. W. Schindler
Keyword(s):  
Gas Exchange ◽  
Organic Carbon ◽  
Film Thickness ◽  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Oligotrophic Lake ◽  
Daughter Product ◽  
Experimental Lakes Area ◽  
Average Value ◽  
Carbon 14

To gain more insight into the nature of carbon cycling in lakes and to provide a check on estimates of carbon fluxes obtained by more conventional means, 1 Ci (= 37 GBq) of C14 as NaHCO3 was added to the epilimnion of Lake 224, a dimictic, oligotrophic lake of the Canadian Shield near Kenora, Ontario. The dominant loss from the dissolved inorganic carbon (DIC) pool was via C14O2 evasion to the overlying atmosphere. The next most important loss from the DIC pool was by photosynthetic fixation of inorganic carbon by epilimnetic phytoplankton. About half of the C14 thus incorporated into the particulate organic carbon (POC) pool was converted into soluble organic molecules which became part of the epilimnetic dissolved organic carbon-14 (DOC) pool. Since the amount of C14 lost to the sediments of the epilimnion, to the hypolimnion, and to periphyton biomass was not significant to the C14 mass balance over the duration of the experiment, the rate of gas exchange can be calculated by measuring the decrease in epilimnetic C14 inventory (DIC14 + POC14 + DOC14) over a specific time period. Using the stagnant boundary model and pCO2 values calculated from pH, temperature and DIC data a range of stagnant film thicknesses of 212–316 μm was obtained. To provide a check on the film thickness calculated from C14 inventories 10 mCi if Ra226 was also added to the epilimnion of L224. Measurements of Rn222, the gaseous daughter product of Ra226, allowed an independent estimate of the film thickness. The average value of 200 μm obtained in this way is consistent with that obtained for C14O2 evasion. A simplified model was also constructed to describe the behavior of the POC and DOC pools. This model produced results in excellent agreement with the photosynthetic rate averaging 65 mg C∙m−1∙d−1 measured using C14 and the Fee incubator technique. The model also suggests that only about 10% of the POC + DOC pool is active in the photosynthetic process on the time scale of 30 d.Key words: whole-lake radiocarbon experiment, gas exchange, primary production, radium226, radon222, carbon14, carbon in lakes

Responses of water yield and dissolved inorganic carbon export to forest recovery in the Houzhai karst basin, southwest China

2013 ◽  
Vol 28 (4) ◽  
pp. 2082-2090 ◽  
Author(s):  
Junhua Yan ◽  
Wantong Wang ◽  
Chuanyan Zhou ◽  
Kun Li ◽  
Shijie Wang
Keyword(s):  
Inorganic Carbon ◽  
Southwest China ◽  
Dissolved Inorganic Carbon ◽  
Forest Recovery ◽  
Water Yield ◽  
Carbon Export

scholarly journals Dissolved inorganic carbon export from carbonate and silicate catchments estimated from carbonate chemistry and δ<sup>13</sup>C<sub>DIC</sub>

2011 ◽  
Vol 8 (1) ◽  
pp. 1799-1825 ◽  
Author(s):  
W. J. Shin ◽  
G. S. Chung ◽  
D. Lee ◽  
K. S. Lee
Keyword(s):  
Stream Flow ◽  
Carbon Budget ◽  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Groundwater Discharge ◽  
Carbonate Chemistry ◽  
River Systems ◽  
Carbon Export ◽  
Carbonate Catchment ◽  
Co2 Degassing

Abstract. We investigated dissolved inorganic carbon (DIC) exchange associated with groundwater discharge and stream flow from two upstream catchments with distinct basement lithology (silicate vs. carbonate). The effects of catchment lithology were evident in the spring waters showing lower δ13CDIC and alkalinity (−16.2 ± 2.7‰ and 0.09 ± 0.03 meq L−1, respectively) in the silicate and higher values (−9.7 ± 1.5‰ and 2.0 ± 0.2 meq L−1) in the carbonate catchment. The streams exhibited relatively high δ13CDIC values, −6.9 ± 1.6‰ and −7.8 ± 1.5‰, in silicate and carbonate catchments, respectively, indicating CO2 degassing during groundwater discharge and stream flow. The catchment lithology affected the pattern of DIC export. The CO2 degassing from stream and groundwater could be responsible for 8–55% of the total DIC export in the silicate catchment, whereas the proportion is comparatively low (0.4–5.6%) in the carbonate catchment. We emphasize the importance of dynamic carbon exchange occurring at headwater regions and its variability with catchment lithology for a more reliable carbon budget in river systems.

scholarly journals Dissolved inorganic carbon export from carbonate and silicate catchments estimated from carbonate chemistry and δ<sup>13</sup>C<sub>DIC</sub>

2011 ◽  
Vol 15 (8) ◽  
pp. 2551-2560 ◽  
Author(s):  
W. J. Shin ◽  
G. S. Chung ◽  
D. Lee ◽  
K. S. Lee
Keyword(s):  
Stream Flow ◽  
Carbon Budget ◽  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Groundwater Discharge ◽  
Carbonate Chemistry ◽  
River Systems ◽  
Carbon Export ◽  
Carbonate Catchment ◽  
Co2 Degassing

Abstract. This work presents a study of the dissolved inorganic carbon (DIC) exchange associated with groundwater discharge and stream flow from two upstream catchments with distinct basement lithologies (silicate vs. carbonate). The effects of catchment lithology were evident in the spring waters showing lower δ13CDIC and alkalinity (−16.2 ± 2.7 ‰ and 0.09 ± 0.03 meq l−1, respectively) in the silicate and higher values (−9.7 ± 1.5 ‰ and 2.0 ± 0.2 meq l−1) in the carbonate catchment. The streams exhibited relatively high δ13CDIC, −6.9 ± 1.6 ‰ and −7.8 ± 1.5 ‰, in silicate and carbonate catchments, respectively, indicating CO2 degassing during groundwater discharge and stream flow. The catchment lithology affected the pattern of DIC export. The CO2 degassing from stream and groundwater could be responsible for 8–55 % of the total DIC export in the silicate catchment, whereas the proportion is comparatively low (0.4–5.6 %) in the carbonate catchment. Therefore, the dynamic carbon exchange occurring at headwater regions and its possible variability with catchment lithology need to be examined for a more reliable carbon budget in river systems.

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