Wyniki wyszukiwania - BazTech

Ograniczanie wyników

1 Geochronometria

1 2011

Znaleziono wyników: 1

Liczba wyników na stronie

Wyniki wyszukiwania

Wyszukiwano:
w słowach kluczowych: ²¹⁰Pb dating

Sortuj według:

Ogranicz wyniki do:

A sedimentation study of St. Ana Lake (Romania) applying the 210 Pb and 137 Cs dating methods.

Begy R. C., Timar-Gabor A., Somlai J., Cosma C.

Geochronometria

2011

Vol. 38, no. 2

93-100

The biggest problem with most lakes that have no contact with other water sources and are being charged by precipitation is the massive eutrophication. The aim of this work was to determine the sedimentation rate in order to evaluate the progress of eutrophication for St. Ana Lake (Ciomad Mountain near the Băile Tuşnad in Harghita County (Romania)). The concentration of 210 Pb was determined by means of high resolution gamma spectrometry as well as derived from 210 Po activity which was measured through alpha spectrometry; values obtained are in good agreement. For the excess 210 Pb activity values between 4.0š0.5 Bq/kg and 218š20 Bq/kg have been found. As an alternative method, the 137 Cs dating method was applied as well. Calculated mass sedimentation rates are in the range of 0.06š0.01 to 0.32š0.05 g/cm 2 year with a mean of value of 0.15š0.02 g/cm 2 year. Linear sedimentation rates yielded much higher sedimentation values (between 0.5š0.1 and 7.9š0.7 cm/year with a mean of 2.4š0.6 cm/year), due to the predominant organic matter composition and the long suspension time of the sediment. This is an indication for the process of eutrophication which will probably lead to the transformation of the lake into a peat bog.