Quantification of decadal anthropogenic CO2 uptake in the ocean based on dissolved inorganic carbon measurements

Nature ◽  
10.1038/25103 ◽  
1998 ◽  
Vol 396 (6711) ◽  
pp. 560-563 ◽  
Author(s):  
Tsung-Hung Peng ◽  
Rik Wanninkhof ◽  
John L. Bullister ◽  
Richard A. Feely ◽  
Taro Takahashi
Keyword(s):  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Co2 Uptake ◽  
Anthropogenic Co2

scholarly journals CO2 Uptake and Fixation by Endosymbiotic Chemoautotrophs from the Bivalve Solemya velum

2006 ◽  
Vol 73 (4) ◽  
pp. 1174-1179 ◽  
Author(s):  
Kathleen M. Scott ◽  
Colleen M. Cavanaugh
Keyword(s):  
Inorganic Carbon ◽  
Carbon Fixation ◽  
Dissolved Inorganic Carbon ◽  
Co2 Uptake ◽  
Maximal Velocity ◽  
Marine Habitats ◽  
Half Saturation Constant ◽  
Oxygen Conditions ◽  
Solemya Velum ◽  
Influence Of Ph

ABSTRACT Chemoautotrophic symbioses, in which endosymbiotic bacteria are the major source of organic carbon for the host, are found in marine habitats where sulfide and oxygen coexist. The purpose of this study was to determine the influence of pH, alternate sulfur sources, and electron acceptors on carbon fixation and to investigate which form(s) of inorganic carbon is taken up and fixed by the gamma-proteobacterial endosymbionts of the protobranch bivalve Solemya velum. Symbiont-enriched suspensions were generated by homogenization of S. velum gills, followed by velocity centrifugation to pellet the symbiont cells. Carbon fixation was measured by incubating the cells with 14C-labeled dissolved inorganic carbon. When oxygen was present, both sulfide and thiosulfate stimulated carbon fixation; however, elevated levels of either sulfide (>0.5 mM) or oxygen (1 mM) were inhibitory. In the absence of oxygen, nitrate did not enhance carbon fixation rates when sulfide was present. Symbionts fixed carbon most rapidly between pH 7.5 and 8.5. Under optimal pH, sulfide, and oxygen conditions, symbiont carbon fixation rates correlated with the concentrations of extracellular CO2 and not with HCO3 − concentrations. The half-saturation constant for carbon fixation with respect to extracellular dissolved CO2 was 28 � 3 μM, and the average maximal velocity was 50.8 � 7.1 μmol min−1 g of protein−1. The reliance of S. velum symbionts on extracellular CO2 is consistent with their intracellular lifestyle, since HCO3 − utilization would require protein-mediated transport across the bacteriocyte membrane, perisymbiont vacuole membrane, and symbiont outer and inner membranes. The use of CO2 may be a general trait shared with many symbioses with an intracellular chemoautotrophic partner.

scholarly journals Towards a more complete quantification of the global carbon cycle

2018 ◽  
Author(s):  
Miko U. F. Kirschbaum ◽  
Guang Zeng ◽  
Fabiano Ximenes ◽  
Donna L. Giltrap ◽  
John R. Zeldis
Keyword(s):  
Land Use ◽  
Land Use Change ◽  
Co2 Emissions ◽  
Fossil Fuels ◽  
Dissolved Inorganic Carbon ◽  
Wood Products ◽  
Co2 Uptake ◽  
River Transport ◽  
Anthropogenic Co2 ◽  
Global Carbon

Abstract. The main components of global carbon budget calculations are the emissions from burning fossil fuels, cement production, and net land-use change, partly balanced by ocean CO2 uptake and CO2 increase in the atmosphere. The remaining difference between these terms is referred to as the residual sink, assumed to correspond to increasing carbon storage in the terrestrial biosphere (ΔB). It is often used to constrain carbon exchange in global earth-system models. More broadly, it guides expectations of autonomous changes in global carbon stocks in response to climatic changes, including increasing CO2, that may add to, or subtract from, anthropogenic CO2 emissions. However, a budget with only these terms omits some important additional fluxes that are important for correctly inferring ΔB. They are cement carbonation and fluxes into increasing pools of plastic, bitumen, harvested-wood products, and landfill deposition after disposal of these products, and carbon fluxes to the oceans via wind erosion and non-CO2 fluxes of the intermediate break-down products of methane and other volatile organic compounds. While the global budget includes river transport of dissolved inorganic carbon it omits river transport of dissolved and particulate organic carbon, and the deposition of carbon in inland water bodies. Each one of these terms is relatively small, but together they can constitute important additional fluxes that would significantly reduce the size of the inferred ΔB. We estimate here that inclusion of these fluxes would reduce ΔB from the currently reported 3.6 down to only about 2.1 GtC yr−1 (excluding losses from land-use change). The implicit reduction in the size of ΔB has important implications for the inferred magnitude of current-day biospheric net carbon uptake and the consequent potential of future biospheric feedbacks to amplify or negate net anthropogenic CO2 emissions.

scholarly journals Impact of seawater carbonate chemistry on the calcification of marine bivalves

2015 ◽  
Vol 12 (2) ◽  
pp. 1543-1571 ◽  
Author(s):  
J. Thomsen ◽  
K. Haynert ◽  
K. M. Wegner ◽  
F. Melzner
Keyword(s):  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Shell Growth ◽  
System Component ◽  
Natural Seawater ◽  
Co2 Uptake ◽  
Similar Response ◽  
Carbonate Chemistry ◽  
Response Curves ◽  
Physiological Processes

Abstract. Bivalve calcification, particular of the early larval stages is highly sensitive to the change of ocean carbonate chemistry resulting from atmospheric CO2 uptake. Earlier studies suggested that declining seawater [CO32−] and thereby lowered carbonate saturation affect shell production. However, disturbances of physiological processes such as acid-base regulation by adverse seawater pCO2 and pH can affect calcification in a secondary fashion. In order to determine the exact carbonate system component by which growth and calcification are affected it is necessary to utilize more complex carbonate chemistry manipulations. As single factors, pCO2 had no and [HCO3−] and pH only limited effects on shell growth, while lowered [CO32−] strongly impacted calcification. Dissolved inorganic carbon (CT) limiting conditions led to strong reductions in calcification, despite high [CO32−], indicating that [HCO3−] rather than [CO32−] is the inorganic carbon source utilized for calcification by mytilid mussels. However, as the ratio [HCO3−] / [H+] is linearly correlated with [CO32−] it is not possible to differentiate between these under natural seawater conditions. Therefore, the availability of [HCO3−] combined with favorable environmental pH determines calcification rate and an equivalent of about 80 μmol kg−1 [CO32−] is required to saturate inorganic carbon supply for calcification in bivalves. Below this threshold biomineralization rates rapidly decline. A comparison of literature data available for larvae and juvenile mussels and oysters originating from habitats differing substantially with respect to prevailing carbonate chemistry conditions revealed similar response curves. This suggests that the mechanisms which determine sensitivity of calcification in this group are highly conserved. The higher sensitivity of larval calcification seems to primarily result from the much higher relative calcification rates in early life stages. In order to reveal and understand the mechanisms that limit or facilitate adaptation to future ocean acidification, it is necessary to better understand the physiological processes and their underlying genetics that govern inorganic carbon assimilation for calcification.

scholarly journals Apparent increase in coccolithophore abundance in the subtropical North Atlantic from 1990 to 2014

2016 ◽  
Vol 13 (4) ◽  
pp. 1163-1177 ◽  
Author(s):  
Kristen M. Krumhardt ◽  
Nicole S. Lovenduski ◽  
Natalie M. Freeman ◽  
Nicholas R. Bates
Keyword(s):  
North Atlantic ◽  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Euphotic Zone ◽  
Ion Concentration ◽  
Biological Communities ◽  
The Past ◽  
The North ◽  
Anthropogenic Co2 ◽  
Mesocosm Experiments

Abstract. As environmental conditions evolve with rapidly increasing atmospheric CO2, biological communities will change as species reorient their distributions, adapt, or alter their abundance. In the surface ocean, dissolved inorganic carbon (DIC) has been increasing over the past several decades as anthropogenic CO2 dissolves into seawater, causing acidification (decreases in pH and carbonate ion concentration). Calcifying phytoplankton, such as coccolithophores, are thought to be especially vulnerable to ocean acidification. How coccolithophores will respond to increasing carbon input has been a subject of much speculation and inspired numerous laboratory and mesocosm experiments, but how they are currently responding in situ is less well documented. In this study, we use coccolithophore (haptophyte) pigment data collected at the Bermuda Atlantic Time-series Study (BATS) site together with satellite estimates (1998–2014) of surface chlorophyll and particulate inorganic carbon (PIC) as a proxy for coccolithophore abundance to show that coccolithophore populations in the North Atlantic subtropical gyre have been increasing significantly over the past 2 decades. Over 1990–2012, we observe a 37 % increase in euphotic zone-integrated coccolithophore pigment abundance at BATS, though we note that this is sensitive to the period being analyzed. We further demonstrate that variability in coccolithophore chlorophyll a here is positively correlated with variability in nitrate and DIC (and especially the bicarbonate ion) in the upper 30 m of the water column. Previous studies have suggested that coccolithophore photosynthesis may benefit from increasing CO2, but calcification may eventually be hindered by low pHT (< 7.7). Given that DIC has been increasing at BATS by  ∼ 1.4 µmol kg−1 yr−1 over the period of 1991–2012, we speculate that coccolithophore photosynthesis and perhaps calcification may have increased in response to anthropogenic CO2 input.

scholarly journals The water column distribution of carbonate system variables at the ESTOC site from 1995 to 2004

2010 ◽  
Vol 7 (10) ◽  
pp. 3067-3081 ◽  
Author(s):  
M. González-Dávila ◽  
J. M. Santana-Casiano ◽  
M. J. Rueda ◽  
O. Llinás
Keyword(s):  
Carbon Dioxide ◽  
Time Series ◽  
Mixed Layer ◽  
Atmospheric Carbon Dioxide ◽  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Total Alkalinity ◽  
Anthropogenic Co2 ◽  
Rate Of Increase ◽  
Atmospheric Carbon

Abstract. The accelerated rate of increase in atmospheric carbon dioxide and the substantial fraction of anthropogenic CO2 emissions absorbed by the oceans are affecting the anthropocenic signatures of seawater. Long-term time series are a powerful tool for investigating any change in ocean bio-geochemistry and its effects on the carbon cycle. We have evaluated the ESTOC (European Station for Time series in the Ocean at the Canary islands) observations of measured pH (total scale at 25 °C) and total alkalinity plus computed total dissolved inorganic carbon concentration (CT) from 1995 to 2004 for surface and deep waters, by following all changes in response to increasing atmospheric carbon dioxide. The observed values for the surface partial pressure of CO2 from 1995 to 2008 were also taken into consideration. The data were treated to better understand the fundamental processes controlling vertical distributions in the Eastern North Atlantic Ocean and the accumulation of anthropogenic CO2, CANT. CT at constant salinity, NCT, increased at a rate of 0.85 μmol kg−1 yr−1 in the mixed layer, linked to an fCO2 increase of 1.7±0.7 μatm yr−1 in both the atmosphere and the ocean. Consequently, the mixed layer at ESTOC site has also become more acidic, −0.0017±0.0003 units yr−1, whereas the carbonate ion concentrations and CaCO3 saturation states have also decreased over time. NCT increases at a rate of 0.53, 0.49 and 0.40 μmol kg−1 yr−1 at 300, 600, and 1000 m, respectively. The general processes controlling the vertical variations of alkalinity and the inorganic carbon distribution were computed by considering the pre-formed values, the production/decomposition of organic matter and the formation/dissolution of carbonates. At 3000 m, 30% of the inorganic carbon production is related to the dissolution of calcium carbonate, increasing to 35% at 3685 m. The total column inventory of anthropogenic CO2 for the decade was 66±3 mol m−2. A model fitting indicated that the column inventory of CANT increased from 61.7 mol m−2 in the year 1994 to 70.2 mol m−2 in 2004. The ESTOC site is presented as a reference site to follow CANT changes in the Northeast Atlantic Sub-tropical gyre.

scholarly journals Towards a more complete quantification of the global carbon cycle

2019 ◽  
Vol 16 (3) ◽  
pp. 831-846 ◽  
Author(s):  
Miko U. F. Kirschbaum ◽  
Guang Zeng ◽  
Fabiano Ximenes ◽  
Donna L. Giltrap ◽  
John R. Zeldis
Keyword(s):  
Land Use ◽  
Land Use Change ◽  
Co2 Emissions ◽  
Dissolved Inorganic Carbon ◽  
Wood Products ◽  
Plant Responses ◽  
Co2 Uptake ◽  
River Transport ◽  
Anthropogenic Co2 ◽  
Global Carbon

Abstract. The main components of global carbon budget calculations are the emissions from burning fossil fuels, cement production, and net land-use change, partly balanced by ocean CO2 uptake and CO2 increase in the atmosphere. The difference between these terms is referred to as the residual sink, assumed to correspond to increasing carbon storage in the terrestrial biosphere through physiological plant responses to changing conditions (ΔBphys). It is often used to constrain carbon exchange in global earth-system models. More broadly, it guides expectations of autonomous changes in global carbon stocks in response to climatic changes, including increasing CO2, that may add to, or subtract from, anthropogenic CO2 emissions. However, a budget with only these terms omits some important additional fluxes that are needed to correctly infer ΔBphys. They are cement carbonation and fluxes into increasing pools of plastic, bitumen, harvested-wood products, and landfill deposition after disposal of these products, and carbon fluxes to the oceans via wind erosion and non-CO2 fluxes of the intermediate breakdown products of methane and other volatile organic compounds. While the global budget includes river transport of dissolved inorganic carbon, it omits river transport of dissolved and particulate organic carbon, and the deposition of carbon in inland water bodies. Each one of these terms is relatively small, but together they can constitute important additional fluxes that would significantly reduce the size of the inferred ΔBphys. We estimate here that inclusion of these fluxes would reduce ΔBphys from the currently reported 3.6 GtC yr−1 down to about 2.1 GtC yr−1 (excluding losses from land-use change). The implicit reduction in the size of ΔBphys has important implications for the inferred magnitude of current-day biospheric net carbon uptake and the consequent potential of future biospheric feedbacks to amplify or negate net anthropogenic CO2 emissions.

scholarly journals Increasing coccolithophore abundance in the subtropical North Atlantic from 1990 to 2014

2015 ◽  
Vol 12 (22) ◽  
pp. 18625-18660
Author(s):  
K. M. Krumhardt ◽  
N. S. Lovenduski ◽  
N. M. Freeman ◽  
N. R. Bates
Keyword(s):  
North Atlantic ◽  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Euphotic Zone ◽  
Ion Concentration ◽  
Biological Communities ◽  
The Past ◽  
The North ◽  
Anthropogenic Co2 ◽  
Mesocosm Experiments

Abstract. As environmental conditions evolve with rapidly increasing atmospheric CO2, biological communities will change as species reorient their distributions, adapt, or alter their abundance. In the surface ocean, dissolved inorganic carbon (DIC) has been increasing over the past several decades as anthropogenic CO2 dissolves into seawater, causing acidification (decreases in pH and carbonate ion concentration). Calcifying phytoplankton, such as coccolithophores, are thought to be especially vulnerable to ocean acidification. How coccolithophores will respond to increasing carbon input has been a subject of much speculation and inspired numerous laboratory and mesocosm experiments, but how they are currently responding in situ is less well documented. In this study, we use coccolithophore pigment data collected at the Bermuda Atlantic Time-series Study (BATS) site together with satellite estimates (1998–2014) of surface chlorophyll and particulate inorganic carbon (PIC) to show that coccolithophore populations in the North Atlantic Subtropical Gyre have been increasing significantly over the past two decades. Over 1991–2012, we observe a 37 % increase in euphotic zone-integrated coccolithophore abundance at BATS. We further demonstrate that variability in coccolithophore abundance here is positively correlated with variability in DIC (and especially the bicarbonate ion) in the upper 30 m of the water column. Previous studies have suggested that coccolithophore photosynthesis may benefit from increasing CO2, but calcification may eventually be hindered by low pHT (< 7.7). Given that DIC has been increasing at BATS by ∼ 1.4 μmol kg−1 yr−1 over 1991 to 2012, we speculate that coccolithophore photosynthesis and perhaps calcification may have increased in response to anthropogenic CO2 input.

CO2 uptake mechanism in Eremosphaera viridis

1998 ◽  
Vol 76 (6) ◽  
pp. 1161-1164
Author(s):  
Jason ST Deveau ◽  
Houman Khosravani ◽  
Roger R Lew ◽  
Brian Colman
Keyword(s):  
Membrane Potential ◽  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Pond Water ◽  
Co2 Uptake ◽  
Uptake Mechanism ◽  
Nitrogen Gas ◽  
Eremosphaera Viridis ◽  
Electrophysiological Measurements ◽  
Free Environment

Electrophysiological measurements of the acidophilic alga Eremosphaera viridis De Bary explored the effects of low CO2 levels on both membrane potential and resistance. This procedure incorporates a double-barreled microelectrode and suction pipette system, coupled with an approximately CO2-free environment. A key requirement is an artificial pond water perfusion media that has been purged of dissolved inorganic carbon by being boiled and bubbled with nitrogen gas. Both membrane potential and resistance were measured at pH5 in both low-CO2 conditions (2µM) and high-CO2 conditions (14µM) in both light, where CO2 transport is known to be active, and dark, where CO2 transport is not active. To avoid dissolved inorganic carbon contamination of the perfusion media, a special chamber was constructed, featuring a laminar flow of nitrogen gas over the solution, which allowed for the manipulation of cells while preventing any contamination by CO2 from the air. Results indicate that the uptake of CO2 by the alga is electrically silent and, therefore, not the result of a symport or antiport cotransport system that would "drive" CO2 uptake by coupling it to the electrochemical gradient of ions such as protons or sodium. The uptake is most likely facilitated by a transporter directly coupled with ATP hydrolysis.Key words: Eremosphaera viridis, dissolved inorganic carbon, CO2-ATPase, electrophysiology.

scholarly journals Impact of seawater carbonate chemistry on the calcification of marine bivalves

2015 ◽  
Vol 12 (14) ◽  
pp. 4209-4220 ◽  
Author(s):  
J. Thomsen ◽  
K. Haynert ◽  
K. M. Wegner ◽  
F. Melzner
Keyword(s):  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Shell Growth ◽  
System Component ◽  
Natural Seawater ◽  
Co2 Uptake ◽  
Similar Response ◽  
Carbonate Chemistry ◽  
Response Curves ◽  
Physiological Processes

Abstract. Bivalve calcification, particularly of the early larval stages, is highly sensitive to the change in ocean carbonate chemistry resulting from atmospheric CO2 uptake. Earlier studies suggested that declining seawater [CO32−] and thereby lowered carbonate saturation affect shell production. However, disturbances of physiological processes such as acid-base regulation by adverse seawater pCO2 and pH can affect calcification in a secondary fashion. In order to determine the exact carbonate system component by which growth and calcification are affected it is necessary to utilize more complex carbonate chemistry manipulations. As single factors, pCO2 had no effects and [HCO3-] and pH had only limited effects on shell growth, while lowered [CO32−] strongly impacted calcification. Dissolved inorganic carbon (CT) limiting conditions led to strong reductions in calcification, despite high [CO32−], indicating that [HCO3-] rather than [CO32−] is the inorganic carbon source utilized for calcification by mytilid mussels. However, as the ratio [HCO3-] / [H+] is linearly correlated with [CO32−] it is not possible to differentiate between these under natural seawater conditions. An equivalent of about 80 μmol kg−1 [CO32−] is required to saturate inorganic carbon supply for calcification in bivalves. Below this threshold biomineralization rates rapidly decline. A comparison of literature data available for larvae and juvenile mussels and oysters originating from habitats differing substantially with respect to prevailing carbonate chemistry conditions revealed similar response curves. This suggests that the mechanisms which determine sensitivity of calcification in this group are highly conserved. The higher sensitivity of larval calcification seems to primarily result from the much higher relative calcification rates in early life stages. In order to reveal and understand the mechanisms that limit or facilitate adaptation to future ocean acidification, it is necessary to better understand the physiological processes and their underlying genetics that govern inorganic carbon assimilation for calcification.

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