ОПТИЧНА ЩІЛЬНІСТЬ ГУМІНОВИХ КИСЛОТ АВТОМОРФНИХ ҐРУНТІВ ПІВНІЧНО-ЗАХІДНОГО ПРИЧОРНОМОР’Я

Abstract

One of the modern and effective methods of studying nature of humic substances is determination of their optical density. The nature of light absorption in the visible and ultraviolet parts of the spectrum is caused by genetic peculiarities of humine acids, i.e. the ratio in their molecules of aromatic and aliphatic structures. Optical density is a measure of the degree condensed aromatic nucleus reflects the soil-climatic conditions of making humus and characterized by the following properties of humine acids as hydrophilicity, mobility, or the tendency to form complex compounds. The value of studies of humic substances rises today as a result of significant losses of humus in soils, changes its fraction-group composition as a result of intensive agricultural use. The regularities of changes of humine acids in zone-the genetic aspect of do not reflect the influence of local conditions of soil formation on the optical properties of humine acids in soils of the same type and within the soil profile. Object is automorphic soils of the North-Western Prichernomorya region, the subject - optical density of humine acids arable chernozems ordinary modal and micellar-carbonate and chernozems southern modal plowing and 40-year-old fallow, chernozems southern, derived from 15 years ago irrigation and chernozems southern carbonate floodplain terraces of the Danube. Determination of optical density were carried out in a extract humine acids which have in the determination of humus. The results of the research showed that the humine acids of the studied automorphous soils of the North-Western Prichernomorya region are characterized by high (0,177–0,195) and very high (0,223–0,275) indicators of optical density. Humine acids in ordinary and southern chernozems characterized by higher molecules` structuring than ordinary micellar-carbonate chernozems and southern carbonate chernozems. The profiles of the studied soils coefficients of optical density of humine acids is gradually rising from the lower limit of the arable layer to the upper limit of transitional horizon, testifying to their structure. Less structured and, accordingly, more hydrophilic molecules of humine acids are concentrated in lower horizons. Not observed correlation of distribution of the coefficients of optical density distribution on the profile of humus. Chromaticity-coefficient (ratio E4: E6) in arable layers of ordinary modal chernozems, southern modal chernozems and off-irrigation southern chernozems is 2,8-2,9. Lesser structurization of humine acids’molecules is noted in ordinary black micellar-carbonate and southern carbonate chernozems, where an increase in the ratio E4: E6 to 3,0-3, 2. On other, the humus in these soils is represented by juvenile, less "matured" humine acids. It was revealed that as a result of domestication southern chernozems grows structure of the molecules of humine acids, as evidenced by an increase of 20 % indicators coefficients of optical density and decrease of the chromaticity – coefficient from 3,2 to 2,8.

Исследовано оптические свойства гуминовых кислот в профилях автоморфных почв Северо-Западного Причерноморья. Выявлено географо-генетические особенности гуминовых кислот в черноземах обыкновенных и южных. Установлено количественные параметры изменения оптической плотности гуминовых кислот при сельскохозяйственном освоении черноземов.