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

scholarly journals Does insect herbivory suppress ecosystem productivity? Evidence from a temperate woodland

2021 ◽  
Author(s):  
Kristiina Visakorpi ◽  
Sofia Gripenberg ◽  
Yadvinder Malhi ◽  
Terhi Riutta
Keyword(s):  
Gas Exchange ◽  
Leaf Area ◽  
Primary Productivity ◽  
Net Primary Productivity ◽  
Leaf Gas Exchange ◽  
Insect Herbivory ◽  
Ecosystem Productivity ◽  
Area Loss ◽  
Leaf Area Loss ◽  
The Relationship

AbstractOur current understanding of the relationship between insect herbivory and ecosystem productivity is limited. Previous studies have typically quantified only leaf area loss, or have been conducted during outbreak years. These set-ups often ignore the physiological changes taking place in the remaining plant tissue after insect attack, or may not represent typical, non-outbreak herbivore densities. Here, we estimate the amount of carbon lost to insect herbivory in a temperate deciduous woodland both through leaf area loss and, notably, through changes in leaf gas exchange in non-consumed leaves under non-outbreak densities of insects. We calculate how net primary productivity changes with decreasing and increasing levels of herbivory, and estimate what proportion of the carbon involved in the leaf area loss is transferred further in the food web. We estimate that the net primary productivity of an oak stand under ambient levels of herbivory is 54 - 69% lower than that of a completely intact stand. The effect of herbivory quantified only as leaf area loss (0.1 Mg C ha−1 yr−1) is considerably smaller than when the effects of herbivory on leaf physiology are included (8.5 Mg C ha−1 yr−1). We propose that the effect of herbivory on primary productivity is non-linear and mainly determined by changes in leaf gas exchange. We call for replicated studies in other systems to validate the relationship between insect herbivory and ecosystem productivity described here.

Photoinhibition of Respiration in Epilithic Periphyton

1987 ◽  
Vol 44 (S1) ◽  
pp. s150-s153 ◽  
Author(s):  
R. W. Graham ◽  
M. A. Turner
Keyword(s):  
Sulfuric Acid ◽  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Dark Respiration ◽  
Gross Photosynthesis ◽  
Dark Control ◽  
Low Concentrations ◽  
Effect Of Light

To determine whether respiration in the light was equal to respiration in the dark we examined epilithic periphyton from a lake acidified experimentally with sulfuric acid. Because of the low concentrations of dissolved inorganic carbon, we could use both 12C and 14C uptake techniques. Using the 14C technique we could correct for residual photosynthesis in samples treated with the photosynthetic inhibitor DCMU (3-(3,4-dichlorophenyl)-1,1-dsmethyiurea). DCMU did not alter rates of dark respiration. However, respiration of DCMU-treated samples in the light was less than in the dark (P < 0.01). This photoinhibition of respiration was about 40% of dark control values. If we had calculated gross photosynthesis for the specific conditions of this experiment, but assumed incorrectly that light and dark respiration were equal, we would have overestimated gross photosynthesis by about 30%. Thus, if the ratio of respiration to photosynthesis is high, researchers will have to evaluate the effect of light on respiration to better estimate gross photosynthesis. The technique we describe, of monitoring both 12C and 14C flux in DCMU-treated samples in the light, will provide an underestimate of respiration in the light.

Stomatal conductance and gas exchange in four species of Caribbean mangroves exposed to ambient and increased CO2

1998 ◽  
Vol 49 (4) ◽  
pp. 325 ◽  
Author(s):  
Samuel C. Snedaker ◽  
Rafael J. Araújo
Keyword(s):  
Stomatal Conductance ◽  
Gas Exchange ◽  
Primary Productivity ◽  
Net Primary Productivity ◽  
South Florida ◽  
Avicennia Germinans ◽  
Laguncularia Racemosa ◽  
Conocarpus Erectus ◽  
Sun Leaves ◽  
Ambient Co2

Stomatal conductance and gas exchange rates in sun leaves were measured in multiple individuals of four species of Caribbean mangroves common to south Florida, USA. Under ambient CO2 levels (340–360 ppm), stomatal conductance (mol m-2 s-1), net primary productivity (g CO2 m-2 min-1), transpiration (g H2O m-2 s-1), and instantaneous transpiration efficiency, ITE, (µmol CO2/mmol H2O) were not significantly different among the four species: Rhizophora mangle (Rm), Avicennia germinans (Ag), Laguncularia racemosa (Lr), and Conocarpus erectus (Ce). Under exposure to increased CO2 (361–485 ppm) there were highly significant (P < 0.001) decreases in stomatal conductance and transpiration, and a highly significant increase in ITE in all four species. However, there was no significant change in net primary productivity in Rm, Ag and Ce, whereas there was a significant decrease (P < 0.01) in net primary productivity in Lr.

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

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.

scholarly journals Annual net primary productivity of a cyanobacteria dominated biological soil crust in the Gulf savanna, Queensland, Australia

2017 ◽  
Author(s):  
Burkhard Büdel ◽  
Wendy J. Williams ◽  
Hans Reichenberger
Keyword(s):  
Gas Exchange ◽  
Primary Productivity ◽  
Net Primary Productivity ◽  
Heterotrophic Bacteria ◽  
Biological Soil Crust ◽  
Net Photosynthesis ◽  
Common Element ◽  
Carbon Gain ◽  
Active Period ◽  
Soil Crust

Abstract. Biological soil crusts are a common element of the Queensland (Australia) dry savannah ecosystem and are composed of cyanobacteria, algae, lichens, bryophytes, fungi and heterotrophic bacteria. Here we report on the annual net primary productivity of a cyanobacteria dominated biological soil crust form the Boodjamulla National Park in north western Queensland using a semi-automatic cuvette system. The dominating cyanobacteria are the filamentous species Sypmplocastrum purpurascens together with Scytonema sp. The recording period lasted from July 1st 2010 to June 30th 2011. Metabolic activity was found from November 2010 until mid-April 2011 only, referring to 23.6 % of the total time of the year. With the onset of the raining season in November, the first month of activity had a pronounced respiratory loss of CO2. Also the last month of the raining season had a negative CO2 balance. Of the metabolic active period, 48.6 % were net photosynthesis and 51.4 % dark respiration. Net photosynthetic uptake of CO2 during daylight was reduced at 32.6 % of the time by water suprasaturation during. In total, the biological soil crust fixed 229.09 mmol CO2 m−2 yr−1, referring to an annual carbon gain of 2.75 g m−2 yr−1. Due to malfunction of the automatic cuvette system, data from September and October 2010, together with days in November and December 2010 could not be analysed for net photosynthesis and respiration. Based on climatic and gas exchange data from November 2010, an estimated loss of 88 mmol CO2 m−2 was found for the two month, resulting in annual rates of 143.08 mmol CO2 m−2 yr−1, equivalent to a carbon gain of 1.72 g m−2 yr−1. The bulk net photosynthetic activity occurred above a relative humidity above 42 %, indicating a suitable climatic combination of temperature and water availability, and a light intensity well above 200 µmol photons m−2 s−1 photosynthetic active radiation. The Boodjamulla biocrust showed a highly seasonally varying CO2 gas exchange pattern divided into metabolically inactive winter month and active summer month. The metabolic active period starts with a period (up to 3 month) of carbon loss, probably due to regrowth before a four month period of carbon gain. This must be taken into consideration for future analyses and modelling of carbon balances in comparable biocrust ecosystems.

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.

scholarly journals Dissolved inorganic carbon and metabolism of an eutrophic lacustrine system: variations from a 36-hours study

2000 ◽  
Vol 60 (4) ◽  
pp. 607-614 ◽  
Author(s):  
P. PEDROSA ◽  
C. E. REZENDE
Keyword(s):  
Carbon Metabolism ◽  
Inorganic Carbon ◽  
Net Primary Productivity ◽  
Dissolved Inorganic Carbon ◽  
Sampling Strategy ◽  
Scientific Data ◽  
Biological Behavior ◽  
Net Mineralization ◽  
Mineralization Of Organic Matter ◽  
Janeiro State

Based on variations of pelagial dissolved inorganic carbon (DIC) concentrations this article provides estimations of net primary productivity and net mineralization -- net carbon metabolism -- in Cima Lake (Rio de Janeiro State). DIC concentrations varied from 203 to 773 µmol L-1 and %CO2(aq) (saturation) from 339 to 4,901. Net carbon metabolism per light/dark periods from the 36 hours of study ranged, respectively, from -556 to 503 mmol DIC m-2 12 h-1. Marked variations in daily net carbon metabolism of the lake were also observed. The values ranged from -25 to -194 mmol DIC m-2 day-1. The findings were discussed as indicators of dynamic biological behavior toward production or mineralization of organic matter in the system. And, the system seemed to shift from heterotrophy to autotrophy. Additionally, in the light of our results we emphasize the axial influence of both sampling strategy and treatment of scientific data for a characterization/interpretation of aquatic systems' metabolism.

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