Radiocarbon carbon tracer

Guilderson, T.P., K. Caldeira, and P.B. Duffy. 2000. Radiocarbon as a diagnostic tracer in ocean and carbon cycle modeling. Global Biogeochemical Cycles 14(3) 887-902. 

Levin, I., and V. Hesshaimer. 2000. Radiocarbon—A unique tracer of global carbon cycle dynamics. Radiocarbon 42 69-80. 

An alternative to the above described approaches is the radiocarbon method that allows a distinction of contemporary carbon (from biogenic emissions and combustion of biomass) and carbon from combustion of fossil fuels in particulate carbonaceous matter [15, 41,42]. In contrast to fossil fuels where the 14C isotope is completely depleted, CM emitted from WB shows a contemporary radiocarbon level. Radiocarbon measurements are often combined with measurements of complementary source specific tracers (macro-tracer) for additional information of source impacts [14, 43, 44]. 

The radioisotope 14C (j8 , 5570 years), which is widely used as a tracer, is made by thermal neutron irradiation of Li or A1 nitride, 14N(n,p)14C. It is available not only as C02 or carbonates, but also in numerous labeled organic compounds. Its formation in the atmosphere and absorption of C02 by living organisms provide the basis of radiocarbon dating. 

As the bomb transient demonstrated the value of radiocarbon as an environmental tracer, availability of tandy might lead to small-scale tracer experiments designed to study the allocation of carbon by plants in namral environments. Because of the high accuracy and high sensitivity of measurements, such tracer experiments can be carried out at a few times the ambient atmospheric ratio and hence... 

Figure 6 shows a schematic overview of the computational strategy. All quantities listed under model parameters are to be determined by the model. These parameters are combined in the vector of independent parameters p. They have to be initialized to start the calculation (see the literature for initialization strategies), and they will be varied in a systematic way in the course of the calculations. Using the initial independent parameters, the model simulates the distributions of all steady-state (temperature, salinity, oxygen, phosphate, nitrate, total inorganic carbon, alkalinity, and radiocarbon) and transient (CFCs) tracers, as in normal forward models. The simulated tracer concentrations are combined in a vector of dependent parameters p. All dependent... 

It is unusual to think of any type of atmospheric contamination - especially by a radioactive species -as beneficial however, bomb-produced radiocarbon (and tritium) has proven to be extremely valuable to oceanographers. The majority of the atmospheric testing, in terms of number of tests and production, occurred over a short time interval, between 1958 and 1963, relative to many ocean circulation processes. This time history, coupled with the level of contamination and the fact that becomes intimately involved in the oceanic carbon cycle, allows bomb-produced radiocarbon to be valuable as a tracer for several ocean processes including biological activity, air-sea gas exchange, thermocline ventilation, upper ocean circulation, and upwelling. 

Carbon dioxide is constantly exchanged between the ocean and atmosphere. Each year the ocean and atmosphere exchange about 350 Gt CO2, with a net ocean uptake currently of about 8 Gt CO2. Because of this exchange, questions arise as to how effective ocean sequestration will be at keeping the CO2 out of the atmosphere. Specifically, is the sequestration permanent, and if not, how fast does the CO2 leak back to the atmosphere. Because there has been no long-term CO2 direct-injection experiment in the ocean, the long-term effectiveness of direct CO2 injection must be predicted based on observations of other oceanic tracers (e.g., radiocarbon) and on computer models of ocean circulation and chemistry. 

Anthropogenic Trace Elements in the Ocean. Cenozoic Oceans - Carbon Cycle Models. Ocean Carbon System, Modeling of. Radiocarbon. Stable Carbon Isotope Variations in the Ocean. Tracers of Ocean Productivity. 

These problems resisted scientific investigation until the advent of modern biochemical methods. One of the most valuable of these new methods proved to be the use of radiocarbon as a tracer element to follow the newly incorporated carbon dioxide during photosynthesis in a green plant. Photosynthesizing plants do not discriminate significantly between ordinary carbon dioxide, C 02, and radioactive carbon dioxide, C 02. The plants incorporate C 02 into the intermediates in the carbon reduction pathway. 

Carbon 14 (1936) n. A heavy radioactive isotope of carbon of mass number 14 used in tracer studies and in dating archaeological and geological materials. Lowe JJ (1997) Radiocarbon dating. John Wiley and Sons, New York. 

Data on the radiocarbon tracer detected in various plant species is shown in Table 12.6. These results confirm that polymer fragments produced by the photodegradation of certain plastic molecules are indeed attacked and metabolized by soil micro-organisms, and are assimilated into the natural carbon cycle. Because radiocarbon assay of the CO2 produced by plant and animal... 

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