Dissolved inorganic carbon

Last updated
Annual DOC and DIC fluxes in the Tanguro Ranch watershed Average annual flux of DOC and DIC in rainfall, throughfall, stemflow, overland flow, and stream flow. Annual DOC and DIC fluxes in the Tanguro Ranch watershed.jpg
Annual DOC and DIC fluxes in the Tanguro Ranch watershed
Average annual flux of DOC and DIC in rainfall, throughfall, stemflow, overland flow, and stream flow.

Dissolved inorganic carbon (DIC) is the sum of the aqueous species of inorganic carbon in a solution. Carbon compounds can be distinguished as either organic or inorganic, and as dissolved or particulate, depending on their composition. Organic carbon forms the backbone of key component of organic compounds such as – proteins, lipids, carbohydrates, and nucleic acids.

Contents

Inorganic carbon is found primarily in simple compounds such as carbon dioxide, carbonic acid, bicarbonate, and carbonate (CO2, H2CO3, HCO−
3, CO2−
3 respectively). Dissolved inorganic carbon (DIC) includes three major aqueous species, CO2, HCO−
3 ,CO2−
3, and to a lesser extent their complexes in solution with metal ions. [3]

Marine ecosystems

Solubility pump

Aqueous carbon dioxide reacts with water to form carbonic acid which is very unstable and will dissociate rapidly into hydronium and bicarbonate. Therefore, in seawater, dissolved inorganic carbon is commonly referred to as the collection of bicarbonate, carbonate ions, and dissolved carbon dioxide (CO2, H2CO3, HCO−
3, CO2−
3).

CO2(aq) + H2O ⇌ H2CO3⇌HCO−
3 + H+⇌CO2−
3 + 2 H+

More than 99% of dissolved inorganic carbon is in the form of bicarbonate and carbonate ions meaning that most of the ocean’s carbon storing ability is due to this chemical reactivity. [4] Sea-air flux of CO2 and the resulting dissolved inorganic carbon is affected by physical processes such as strong winds and vertical mixing, and the biological processes of photosynthesis, respiration, and decomposition. [5]

Biological pump

Dissolved inorganic carbon is a key component of the biological pump, which is defined as the amount of biologically produced organic carbon flux from the upper ocean to the deep ocean. [6] Dissolved inorganic carbon in the form of carbon dioxide is fixed into organic carbon is produced through photosynthesis. Respiration is the reverse process and consumes organic carbon to produce inorganic carbon. Photosynthesis, and the biological pump, is dependent on the availability of inorganic nutrients and carbon dioxide. [7]

Photosynthesis: 6 CO2 + 6 H2O + light → C6H12O6 + 6 O2
Respiration: C6H12O6 + 6 O2 → 6 CO2 + 6 H2O + energy

Oceanographers seek to understand the metabolic state of the ocean, or the efficiency of the biological pump, by estimating the net community production (NCP) which is the gross primary productivity (GPP) minus the community respiration (sum of the respiration of the local autotrophs and heterotrophs). [8] An efficient biological pump increases biological export to the deeper ocean which has been hypothesized to suppress CO2 outgassing in the upper ocean. [9] [10]

WOA05 GLODAP pd DIC AYool.png
"Present day" (1990s)
WOA05 GLODAP pi DIC AYool.png
Pre-industrial (1700s)
           Sea surface DIC concentration (from GLODAP climatology)
Spatial distribution of ocean surface DIC Spatial distributions of DIC and nDIC. (a) DIC (normalized to year 2005); (b) salinity-normalized DIC (nDIC, DIC normalized to reference year of 2005 and salinity of 35) in the surface global ocean. The latitudinal trends are clear, particularly for nDIC. Spatial distribution of ocean surface dissolved inorganic carbon.png
Spatial distribution of ocean surface DIC
Spatial distributions of DIC and nDIC. (a) DIC (normalized to year 2005); (b) salinity-normalized DIC (nDIC, DIC normalized to reference year of 2005 and salinity of 35) in the surface global ocean. The latitudinal trends are clear, particularly for nDIC.

Carbonate pump

The carbonate pump is sometimes referred to as the “hard tissue” component of the biological pump. [12] Some surface marine organisms, like Coccolithophores, produce hard structures out of calcium carbonate, a form of particulate inorganic carbon, by fixing bicarbonate. [13] This fixation of DIC is an important part of the oceanic carbon cycle.

Ca2+ + 2 HCO−
3 → CaCO3 + CO2 + H2O

While the biological carbon pump fixes inorganic carbon (CO2) into particulate organic carbon in the form of sugar (C6H12O6), the carbonate pump fixes inorganic bicarbonate and causes a net release of CO2. [14] In this way, the carbonate pump could be termed the carbonate counter pump. It works counter to the biological pump by counteracting the CO2 flux from the biological pump.

Measurement

Oceanographers and engineers continue to find novel and more accurate methods of measuring carbon content in seawater. One method is to collect water samples and directly measure the DIC by using a TOC analyzer. [15] Samples can be combined with stable isotope ratios 13C/12C, alkalinity measurements, and estimation of physical processes, to create diagnostic techniques. [16] Researchers at Scripps Institution of Oceanography developed a tool that uses flow injection analysis to measures microfluidic samples of seawater and continuously monitor dissolved inorganic carbon content. [17]

See also

Related Research Articles

<span class="mw-page-title-main">Bicarbonate</span> Polyatomic anion

In inorganic chemistry, bicarbonate is an intermediate form in the deprotonation of carbonic acid. It is a polyatomic anion with the chemical formula HCO−
3.

<span class="mw-page-title-main">Carbon dioxide</span> Chemical compound with formula CO₂

Carbon dioxide is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature, and as the source of available carbon in the carbon cycle, atmospheric CO2 is the primary carbon source for life on Earth. In the air, carbon dioxide is transparent to visible light but absorbs infrared radiation, acting as a greenhouse gas. Carbon dioxide is soluble in water and is found in groundwater, lakes, ice caps, and seawater. When carbon dioxide dissolves in water, it forms carbonate and mainly bicarbonate, which causes ocean acidification as atmospheric CO2 levels increase.

<span class="mw-page-title-main">Carbonate</span> Salt of carbonic acid

A carbonate is a salt of carbonic acid (H2CO3), characterized by the presence of the carbonate ion, a polyatomic ion with the formula CO2−3. The word carbonate may also refer to a carbonate ester, an organic compound containing the carbonate group C(=O)(O–)2.

<span class="mw-page-title-main">Carbon cycle</span> Natural processes of carbon exchange

The carbon cycle is that part of the biogeochemical cycle by which carbon is exchanged among the biosphere, pedosphere, geosphere, hydrosphere, and atmosphere of Earth. Other major biogeochemical cycles include the nitrogen cycle and the water cycle. Carbon is the main component of biological compounds as well as a major component of many minerals such as limestone. The carbon cycle comprises a sequence of events that are key to making Earth capable of sustaining life. It describes the movement of carbon as it is recycled and reused throughout the biosphere, as well as long-term processes of carbon sequestration (storage) to and release from carbon sinks.

<span class="mw-page-title-main">Coccolithophore</span> Unicellular algae responsible for the formation of chalk

Coccolithophores, or coccolithophorids, are single-celled organisms which are part of the phytoplankton, the autotrophic (self-feeding) component of the plankton community. They form a group of about 200 species, and belong either to the kingdom Protista, according to Robert Whittaker's five-kingdom system, or clade Hacrobia, according to a newer biological classification system. Within the Hacrobia, the coccolithophores are in the phylum or division Haptophyta, class Prymnesiophyceae. Coccolithophores are almost exclusively marine, are photosynthetic, and exist in large numbers throughout the sunlight zone of the ocean.

In chemistry, carbonic acid is an organic compound with the chemical formula H2CO3. The molecule rapidly converts to water and carbon dioxide in the presence of water; however, in the absence of water, contrary to popular belief, it is quite stable at room temperature. The interconversion of carbon dioxide and carbonic acid is related to the breathing cycle of animals and the acidity of natural waters.

<span class="mw-page-title-main">Biological pump</span> Carbon capture process in oceans

The biological pump (or ocean carbon biological pump or marine biological carbon pump) is the ocean's biologically driven sequestration of carbon from the atmosphere and land runoff to the ocean interior and seafloor sediments. In other words, it is a biologically mediated process which results in the sequestering of carbon in the deep ocean away from the atmosphere and the land. The biological pump is the biological component of the "marine carbon pump" which contains both a physical and biological component. It is the part of the broader oceanic carbon cycle responsible for the cycling of organic matter formed mainly by phytoplankton during photosynthesis (soft-tissue pump), as well as the cycling of calcium carbonate (CaCO3) formed into shells by certain organisms such as plankton and mollusks (carbonate pump).

A hydrogen ion is created when a hydrogen atom loses or gains an electron. A positively charged hydrogen ion (or proton) can readily combine with other particles and therefore is only seen isolated when it is in a gaseous state or a nearly particle-free space. Due to its extremely high charge density of approximately 2×1010 times that of a sodium ion, the bare hydrogen ion cannot exist freely in solution as it readily hydrates, i.e., bonds quickly. The hydrogen ion is recommended by IUPAC as a general term for all ions of hydrogen and its isotopes. Depending on the charge of the ion, two different classes can be distinguished: positively charged ions and negatively charged ions.

<span class="mw-page-title-main">Alkalinity</span> Capacity of water to resist changes in pH that would make the water more acidic

Alkalinity (from Arabic: القلوي, romanized: al-qaly, lit. 'ashes of the saltwort') is the capacity of water to resist acidification. It should not be confused with basicity, which is an absolute measurement on the pH scale. Alkalinity is the strength of a buffer solution composed of weak acids and their conjugate bases. It is measured by titrating the solution with an acid such as HCl until its pH changes abruptly, or it reaches a known endpoint where that happens. Alkalinity is expressed in units of concentration, such as meq/L (milliequivalents per liter), μeq/kg (microequivalents per kilogram), or mg/L CaCO3 (milligrams per liter of calcium carbonate). Each of these measurements corresponds to an amount of acid added as a titrant.

<span class="mw-page-title-main">Solubility pump</span> Physico-chemical process which transports carbon

In oceanic biogeochemistry, the solubility pump is a physico-chemical process that transports carbon as dissolved inorganic carbon (DIC) from the ocean's surface to its interior.

pCO<sub>2</sub> Partial pressure of carbon dioxide, often used in reference to blood

pCO2, pCO2, or is the partial pressure of carbon dioxide (CO2), often used in reference to blood but also used in meteorology, climate science, oceanography, and limnology to describe the fractional pressure of CO2 as a function of its concentration in gas or dissolved phases. The units of pCO2 are mmHg, atm, torr, Pa, or any other standard unit of atmospheric pressure. The pCO2 of Earth's atmosphere has risen from approximately 280 ppm (parts-per-million) to a mean 2019 value of 409.8 ppm as a result of anthropogenic release of carbon dioxide from fossil fuel burning. This is the highest atmospheric concentration to have existed on Earth for at least the last 800,000 years.

<span class="mw-page-title-main">Siliceous ooze</span> Biogenic pelagic sediment located on the deep ocean floor

Siliceous ooze is a type of biogenic pelagic sediment located on the deep ocean floor. Siliceous oozes are the least common of the deep sea sediments, and make up approximately 15% of the ocean floor. Oozes are defined as sediments which contain at least 30% skeletal remains of pelagic microorganisms. Siliceous oozes are largely composed of the silica based skeletons of microscopic marine organisms such as diatoms and radiolarians. Other components of siliceous oozes near continental margins may include terrestrially derived silica particles and sponge spicules. Siliceous oozes are composed of skeletons made from opal silica SiO2·nH2O, as opposed to calcareous oozes, which are made from skeletons of calcium carbonate (CaCO3·nH2O) organisms (i.e. coccolithophores). Silica (Si) is a bioessential element and is efficiently recycled in the marine environment through the silica cycle. Distance from land masses, water depth and ocean fertility are all factors that affect the opal silica content in seawater and the presence of siliceous oozes.

<span class="mw-page-title-main">Carbonate–silicate cycle</span> Geochemical transformation of silicate rocks

The carbonate–silicate geochemical cycle, also known as the inorganic carbon cycle, describes the long-term transformation of silicate rocks to carbonate rocks by weathering and sedimentation, and the transformation of carbonate rocks back into silicate rocks by metamorphism and volcanism. Carbon dioxide is removed from the atmosphere during burial of weathered minerals and returned to the atmosphere through volcanism. On million-year time scales, the carbonate-silicate cycle is a key factor in controlling Earth's climate because it regulates carbon dioxide levels and therefore global temperature.

<span class="mw-page-title-main">Bjerrum plot</span> Graph of polyprotic acid concentration compared to pH

A Bjerrum plot (named after Niels Bjerrum), sometimes also known as a Sillén diagram (after Lars Gunnar Sillén), or a Hägg diagram (after Gunnar Hägg) is a graph of the concentrations of the different species of a polyprotic acid in a solution, as a function of pH, when the solution is at equilibrium. Due to the many orders of magnitude spanned by the concentrations, they are commonly plotted on a logarithmic scale. Sometimes the ratios of the concentrations are plotted rather than the actual concentrations. Occasionally H+ and OH− are also plotted.

The Revelle factor (buffer factor) is the ratio of instantaneous change in carbon dioxide (CO2) to the change in total dissolved inorganic carbon (DIC), and is a measure of the resistance to atmospheric CO2 being absorbed by the ocean surface layer. The buffer factor is used to examine the distribution of CO2 between the atmosphere and the ocean, and measures the amount of CO2 that can be dissolved in the mixed surface layer. It is named after the oceanographer Roger Revelle. The Revelle factor describes the ocean's ability to uptake atmospheric CO2, and is typically referenced in global carbon budget analysis and anthropogenic climate change studies.

<span class="mw-page-title-main">Oceanic carbon cycle</span> Ocean/atmosphere carbon exchange process

The oceanic carbon cycle is composed of processes that exchange carbon between various pools within the ocean as well as between the atmosphere, Earth interior, and the seafloor. The carbon cycle is a result of many interacting forces across multiple time and space scales that circulates carbon around the planet, ensuring that carbon is available globally. The Oceanic carbon cycle is a central process to the global carbon cycle and contains both inorganic carbon and organic carbon. Part of the marine carbon cycle transforms carbon between non-living and living matter.

<span class="mw-page-title-main">Marine biogenic calcification</span> Shell formation mechanism

Marine biogenic calcification is the process by which marine organisms such as oysters and clams form calcium carbonate. Seawater is full of dissolved compounds, ions and nutrients that organisms can use for energy and, in the case of calcification, to build shells and outer structures. Calcifying organisms in the ocean include molluscs, foraminifera, coccolithophores, crustaceans, echinoderms such as sea urchins, and corals. The shells and skeletons produced from calcification have important functions for the physiology and ecology of the organisms that create them.

The sulfate-methane transition zone (SMTZ) is a zone in oceans, lakes, and rivers found below the sediment surface in which sulfate and methane coexist. The formation of a SMTZ is driven by the diffusion of sulfate down the sediment column and the diffusion of methane up the sediments. At the SMTZ, their diffusion profiles meet and sulfate and methane react with one another, which allows the SMTZ to harbor a unique microbial community whose main form of metabolism is anaerobic oxidation of methane (AOM). The presence of AOM marks the transition from dissimilatory sulfate reduction to methanogenesis as the main metabolism utilized by organisms.

<span class="mw-page-title-main">Total inorganic carbon</span> Sum of the inorganic carbon species

Total inorganic carbon is the sum of the inorganic carbon species.

<span class="mw-page-title-main">Particulate inorganic carbon</span>

Particulate inorganic carbon (PIC) can be contrasted with dissolved inorganic carbon (DIC), the other form of inorganic carbon found in the ocean. These distinctions are important in chemical oceanography. Particulate inorganic carbon is sometimes called suspended inorganic carbon. In operational terms, it is defined as the inorganic carbon in particulate form that is too large to pass through the filter used to separate dissolved inorganic carbon.

References

  1. ↑ Environmental Research at Tanguro Ranch, Brazil Esri. Retrieved 26 July 2020.
  2. ↑ Neu, V., Ward, N.D., Krusche, A.V. and Nill, C. (2016) "Dissolved organic and inorganic carbon flow paths in an Amazonian transitional forest". Frontiers in Marine Science, 3: 114. doi : 10.3389/fmars.2016.00114. CC-BY icon.svg Material was copied from this source, which is available under a Creative Commons Attribution 4.0 International License.
  3. ↑ Mackenzie FT and Lerman A (2006) Carbon in the Geobiosphere: Earth's Outer Shell, Springer Science & Business Media. ISBN   9781402042386.
  4. ↑ Williams, Richard G.; Follows, Michael J. (14 July 2011). Ocean Dynamics and the Carbon Cycle: Principles and Mechanisms. Cambridge, UK: Cambridge University Press. pp. 7–9. ISBN   978-0521843690.
  5. ↑ Ma, W; Chai, F; Xiu, P; Tian, J (2014). "Simulation of export production and biological pump structure in the South China Sea". Geo-Marine Letters. 34 (6): 541–554. Bibcode:2014GML....34..541M. doi:10.1007/s00367-014-0384-0. S2CID   129982048.
  6. ↑ Emerson, Steven (2014). "Annual net community production and the biological carbon flux in the ocean". Global Biogeochemical Cycles. 28 (1): 14–28. Bibcode:2014GBioC..28...14E. doi: 10.1002/2013GB004680 .
  7. ↑ Raymond, Peter A.; Bauer, James E. (2000). "Atmospheric CO2 evasion, dissolved inorganic carbon production, and net heterotrophy in the York River estuary". Limnol. Oceanogr. 45 (8): 1707–1717. Bibcode:2000LimOc..45.1707R. doi: 10.4319/lo.2000.45.8.1707 .
  8. ↑ Ducklow, H.W.; Doney, S.C. (2013). "What is the Metabolic State of the Oligotrophic Ocean? A Debate". Annual Review of Marine Science. 5: 525–33. doi:10.1146/annurev-marine-121211-172331. hdl: 1912/5282 . PMID   22809191.
  9. ↑ Ma, W; Chai, F; Xiu, P; Tian, J (2014). "Simulation of export production and biological pump structure in the South China Sea". Geo-Marine Letters. 34 (6): 541–554. Bibcode:2014GML....34..541M. doi:10.1007/s00367-014-0384-0. S2CID   129982048.
  10. ↑ Kim, H.J.; Kim, T.-W; Hyeong, K; Yeh, S.-W.; Park, J.-Y.; Yoo, C.M.; Hwang, J. (2019). "Suppressed CO2 Outgassing by an Enhanced Biological Pump in the Eastern Tropical Pacific". Journal of Geophysical Research: Oceans. 124 (11): 7962–7973. Bibcode:2019JGRC..124.7962K. doi:10.1029/2019JC015287. S2CID   210611691.
  11. ↑ Wu, Y., Hain, M.P., Humphreys, M.P., Hartman, S. and Tyrrell, T. (2019) "What drives the latitudinal gradient in open-ocean surface dissolved inorganic carbon concentration?" Biogeosciences, 16(13): 2661–2681. doi:10.5194/bg-16-2661-2019. CC-BY icon.svg Material was copied from this source, which is available under a Creative Commons Attribution 4.0 International License.
  12. ↑ Hain, M.P.; Sigman, D.M.; Haug, G.H (2014). "The Biological Pump in the Past". Treatise on Geochemistry. 8: 485–517. doi:10.1016/B978-0-08-095975-7.00618-5. ISBN   9780080983004.
  13. ↑ Rost, Bjorn; Reibessel, Ulf (2004). Coccolithophores and the biological pump: responses to environmental changes. Berlin, Heidelberg: Springer. ISBN   978-3-642-06016-8.
  14. ↑ Rost, Bjorn; Reibessel, Ulf (2004). Coccolithophores and the biological pump: responses to environmental changes. Berlin, Heidelberg: Springer. ISBN   978-3-642-06016-8.
  15. ↑ Raymond, Peter A.; Bauer, James E. (2000). "Atmospheric CO2 evasion, dissolved inorganic carbon production, and net heterotrophy in the York River estuary". Limnol. Oceanogr. 45 (8): 1707–1717. Bibcode:2000LimOc..45.1707R. doi: 10.4319/lo.2000.45.8.1707 .
  16. ↑ Gruber, Nicolas; Kneeling, Charles D.; Stocker, Thomas F. (1998). "Carbon-13 constraints on the seasonal inorganics carbon budget at the BATS site in the northwestern Sargasso Sea". Deep-Sea Research Part I. 45 (4–5): 673–717. Bibcode:1998DSRI...45..673G. doi:10.1016/S0967-0637(97)00098-8.
  17. ↑ Bresnahan, Philip J.; Martz, Todd R. (2018). "Gas Diffusion Cell Geometry for a Microfluidic Dissolved Inorganic Carbon Analyzer". IEEE Sensors Journal. 8 (6): 2211–2217. Bibcode:2018ISenJ..18.2211B. doi: 10.1109/JSEN.2018.2794882 . S2CID   3475999.
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.