Gunārs Bremanis, Maris Klaviņš, Oskars Purmalis, Raitis Ziemelis and Solveiga Maļecka
Extracts for agricultural use were prepared using cavitation method at 45 oC and at 95 oC from peat and earthworm biohumus. Samples of all studied extracts had similar dry-matter content. Peat humic substances and earthworm biohumus extracts were analysed using UV-Vis, FT-IR, and fluorescence spectrometry. Trace element analysis was performed with atomic absorption spectrometry. Extracts were tested for acidity, conductivity, humic acid concentration, and carboxyl group concentration. Hydrophobicity was assessed using a water-polyethylene glycol twophase system and calculation of the partition coefficient. Total nitrogen and phosphorus concentration was determined. Concentration of the humic substances slightly changed during the heating process. Significant changes in total phosphorus concentration was observed both in earthworm humus and peat extract. Thermal treatment caused decrease of hydrophobicity and lower concentration of organic matter in extracts, while carboxyl group concentrations in isolated humic substances practically did not change. The calculated ratio from UV-Vis spectra showed significant difference in humification degree of samples.
Inese Silamiķele, Oļgerts Nikodemus, Laimdota Kalniņa, Oskars Purmalis and Māris Kļaviņš
aqueous phases of a peat bog profile using molecular fluorescence spectroscopy, ESR and FT-IR, and comparison with physical properties. Org. Geochem. , 34 , 49-60.
Fong, S. S., Mohamed, M. (2007). Chemical characterization of humic substances occurring in the peats of Sarawak, Malaysia. Org. Geochem. , 38 (6), 967-976.
Ghaly, R. A., Pyke, J. B., Ghaly, A. E., Ugursal, V. I. (1999). Remediation of diesel-oil-contaminated soil using peat. Energy Sources, A: Recovery, Utilization, and Environmental Effects
V.A. Bazhenov, O.S. Pogorelova and T.G. Postnikova
state-of-art technique for nonstationary signals analysis. There are quite a few articles, books, and textbooks written on them [ 11 , 12 , 13 , 14 ]. There is developed Software: Wavelet Toolbox in Matlab, Mathcad and so on [ 15 ].
Mathematical transformations are applied to signals to obtain a further information from signal that is not readily available in the raw signal. There is number of transformations that can be applied, among which the Fourier transforms (FT) are probably by far the most popular.
The FT gives the frequency information of the signal