Saturday, 15 July 2006

Change of Ecological and Biological Properties of Chernozem Ordinary at Pollution by Technogenic Products of Nonmetallic Nature.

Sergei I. Kolesnikov and Anna A. Popovich. Rostov State Univ, B. Sadovaya Str., 105, Rostov-on-Don, 344006, Russia

A number of modelling experiments has been incorporated. As object of research, the chernozem ordinary (the Rostov area, Russia) has been used. The soil for modelling experiments has been taken from an arable horizon. Pollution of soil by nonmetallic technogenic products (As, Se, F, B) has been investigated. Studied action of different concentration of polluting substances - 1, 10, and 100 maximum concentration limits. Maximum concentration limit in soil is 50 mg/kg of air-dried soil, Se - 10, F - 500, B - 100. Soil was incubated at optimum temperature and humidity. Laboratory-analytical definition of properties of soil carried out in 10, 30, and 90 days after pollution. Determined number and activity of microorganisms, enzyme activity, phytotoxicity of soils, humus content, the contents of feed elements, acid-alkaline conditions, etc. As a result of research the following is established. Pollution by technogenic products the nonmetallic nature (F, B, Se, As), in the overwhelming majority of cases, leads to deterioration of ecological biological properties of chernozem ordinary. In the overwhelming majority of cases, values of all investigated parameters are reduced. Only the increase in number of ammonifying bacteria and micromycetes and activity of enzymes is on occassion fixed. It was observed, as a rule, at pollution of soil 1 maximum concentration limits or less often than 10 maximum concentration limits of polluting substance. A little bit more often stimulation was observed at definition of phytotoxicity properties, speed of decomposition of urea. The greatest stimulating effect from the investigated elements was fluorine. Reactions ammonifying bacteria and micromycetes on pollution of chernozem ordinary F, B, Se, As have opposite effect: in relation to bacteria, the negative effect is shown in the beginning, and in due course is reduced, in relation to micromycetes - it amplifies in due course. Ammonifying bacteria have proved steadier to the given kind of pollution than micromycetes. Similar results have been received earlier at pollution of soil by heavy metals. From the investigated elements, the greatest negative influence on properties of chernozem ordinary (in the investigated concentration) renders a pine forest less strong - selenium and arsenic, the least - fluorine. On a degree of deterioration of properties of chernozem ordinary the investigated elements form the following line: B> Se> As> F. Essential influence is rendered with a doze of polluting substance. In most cases, the above concentration of nonmetal - pollution in soil, the is more strongly reduced its biological activity. The great value from parameters of pollution has term from the moment of pollution. At pollution by a pine forest and arsenic toxic action in relation to the majority of ecological biological properties of chernozem ordinary eventually is a little reduced, and at pollution by fluorine and selenium, on the contrary, amplifies. On a degree of stability to pollution by phytotoxicity tehnogenic products the nonmetallic nature biological properties of soils settle down as follows: phytotoxicity > speed of decomposition of urea> dehy-drogenase activity = invartase activity = urease activity > catalase activity > number of ammonifying bacteria> number of micromycetes > Azotobacter> cellulosolitic ability> "breath" of soil.

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