Wyniki wyszukiwania - BazTech

1

Radiocarbon concentration in urban area

Rakowski A. Z., Kuc T., Nakamura T., Pazdur A.

Geochronometria

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2005

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Vol. 24

63-68

EN

Radiocarbon concentration has decreased in recent years due to the exchange of 14CO2 between the atmosphere and the oceans, but also due to 12CO2 emission from burning fossil fuels. This second phenomenon known as Suess effect can be observed in the highly industrialized and/or urban areas. New data of radiocarbon concentration in tree rings from Nagoya (Central Japan) and Kraków (Poland), which covered last 20 years, were obtained recently. These data were used to find the relationship between the radiocarbon concentrations in atmosphere and biosphere. Additionally, data of radiocarbon concentration in atmospheric CO2 in Kraków were compared with those derived from annual tree rings, to calculate the time of CO2 uptake for pine trees in this region. These data show that radiocarbon concentration of the CO2 in .urban air. is systematically lower than that in "clean air". Data of radiocarbon concentration were fitted by exponential and linear functions to calculate the time of exchange and predict the future level. Using data of carbon dioxide and radiocarbon concentration from Schauinsland fossil component Cf in carbon dioxide concentration level was calculated in Nagoya and Kraków.

2

Nonlinear methods of analysis of data with gaps

Dergachev V. A., Makarenko N. G., Karimova L. N., Danilkina E. B.

Geochronometria

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2001

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Vol. 20

45-50

EN

Information on most of natural phenomena can be obtained from time series of direct and proxy data. The analysis of time series generated by natural dynamic systems is a key element in interpreting geophysical and climatic information. Unfortunately, most of available time series have gaps. When there are many gaps with irregular distribution, we do not have any statistical tools for repairing the data. We suggest some approach to solve this problem. It is based on modeling the missing data by small-dimensional manifolds and neural network technologies. In this approach we assume that data under consideration are a set of n-dimensional vectors, which are produced by dynamical system. These vectors model n-dimensional attractor in embedding space. Gaps in the vectors are represented as a linear manifold L of some dimension. The method idea is to model L by another small-dimensional manifold, e.g. a curve. Neural networks are used to find this manifold. We verify the method on real time series data: sunspot numbers, the radiocarbon content in tree rings, the 10Be in ice cores, the width of tree rings and so on.

3

Radiocarbon concentration measurements in contemporary tree rings from Upper Silesia

Rakowski A. Z., Pawełczyk S., Pazdur A.

Geochronometria

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2000

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Vol. 18

19-22

EN

Upper Silesia is an example of the most industrially changed natural environment in Poland. This state is a consequence of mining development in the last 150 years as well as accumulation of a number of towns and industrial companies with high impact to the environment. A decrease of radiocarbon concentration resulted from the "Suess effect" was observed in the Upper Silesia region. Estimation of this effect, on the basis of carbon isotope analysis in annual tree rings collected from trees growing in the region considered, has been carried out.

4

Delta 13C in tree rings alfa-cellulose. A methodology of measurements and interpretation: state of the art

Pawełczyk S., Pazdur A.

Geochronometria

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2000

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Vol. 18

15-18

EN

The development of a tree is dependent upon the climatic and environmental conditions under which it grows. Formed growth rings represent integration of these variables during each growing season. More parameters other than ring-width are required to produce satisfactory reconstruction of past environmental changes. Stable isotope variations within the growth rings may provide other parameters. The variation of delta13C indices in the latewood alpha-cellulose is highly correlated with combined July and August environmental variables. Investigation of isotopic carbon composition in annual tree rings from Upper Silesia and ecologically clean Augustów Wilderness region were recently undertaken in the 14C Laboratory in Gliwice. In that time a series of radiocarbon concentration measurements in single tree rings and delta13C in the entire organic matter were carried out. Such evaluated values of delta 13C are used to correct radiocarbon concentration. However they cannot be used to reconstruct climatic and environmental conditions.