Abstract
We present results of Multifractal Detrended Fluctuation Analysis (MF-DFA) of soil radon (Rn-222) and thoron (Rn-220) time series to examine the scaling and multifractal features. Data consists of 15,692 measurements taken each over forty-minute interval. RTM 1688-2 Rn-222/Rn-220 electronic device has been used for measurement purposes. Seasonal periodicities have been removed from the data and MF-DFA was employed on de-seasonalized data. Original Rn-222 and Rn-220 time series have been converted into surrogated and shuffled time series. MF-DFA has also been applied to the surrogated and shuffled series to examine the multifractality nature. Results of the study show that Rn-222(Or)ig, Rn-222(Su)ur(r) and Or(ig)(220)Rn, Su(ur)(r)(220)Rn time series are long-range positively correlated and an increase or decrease in either of radionuclide concentrations will be followed by another increase or decrease of concentrations in future measurements. The Rn-220(Sh)uff time series has an independent or short-range dependent structure called white noise and the shuffled time series exhibit a very weak multifractality.