Organochlorine pesticides have been used widely in agriculture for effective pest control. However, organochlorine pesticides such as dichloro-diphenyl-trichloroethane (DDT) contaminate soil, ...groundwater and cause carcinogenic effects, reproductive disorders for birds, humans and other mammals. Consequently, the use of DDT in agriculture has been gradually forbidden since 1972. Nevertheless, due to the long halflife of DDT (~36 years), its residues are still present in the soil. Therefore, there is a need to find a method for the treatment of this dangerous contaminant in the soil. This experimental research is aimed to analyse thermal air and water vapour plasmas eligibility to remediate soil contaminated by organochlorine pesticides (mainly DDT). Hence, parameters of the polluted soil were investigated before and after the treatment with thermal plasma using scanning electron microscopy (SEM), an optical microscope, a photo camera, energy dispersive X-ray spectroscopy (EDX) and gas chromatography-mass spectrometry (GC-MS). SEM analysis revealed that interaction of polluted soil with thermal air plasma or water vapour plasma caused structural changes of the soil. EDX data demonstrated complete removal of chlorine after the soil cleaning with plasmas. Moreover, the measurements performed with GCMS confirmed that organochlorine pesticides concentrations in the soil were reduced noticeably after the soil cleaning with thermal plasmas. Thus, experimental results indicate that contaminated soil treatment using thermal air or water vapour plasma has satisfactory pesticides degradation capacity.
The energetics of hydration of natural DNA of different AT/GC content and model double-helical polyribonucleotides was studied. The results obtained by a new approach, which is based on calorimetric ...measurements of hydration-dehydration energy of nucleic acid-water systems at different relative humidities are presented. A correlation between the dehydration energy and the nucleotide composition of native DNA was found. The energetic characteristics of systems containing deoxynucleoside monophosphates and water clusters of different dimensions were obtained by the Monte Carlo method. The results of computer simulation correlate with the experimental calorimetric data.
The hydration energetics of natural DNA with various AT/GC-composition and model double-helix polyribonucleotides was studied using a new approach which is based on calorimetric measurements of the ...dehydration energy of nucleic acid-water systems at various levels of relative humidity. A linear correlation between the dehydration energy and the nucleotide composition of natural DNA was found.
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