Informative indicators of the ecological state of soil exposed to low stress factors: pollution, drought, acidity

Abstract

The article is devoted to the problem of choosing informative indicators of the ecological state of soil with a low stress factor. The purpose of this work is to compare toxicological (ex situ) and bioindicative indicators (in situ) of soil under conditions of pollution, drought, and increased acidity. The number of zymogenic and oligotrophic microflora, the activity of catalase and urease exoenzymes, including the acute toxicity of soil extracts in tests for Paramecium caudatum and Escherichia coli were determined in soil samples. Most of the reactions observed ex situ and in situ were hormetic or equal to the control. As compared to the control, an increase in the number was noted in oligocarbophiles in moderately acidic soil (by 13 times), in oligotrophs in drought-exposed soil (by 22 times), in amylolytics in contaminated and acidic soil (by 6 times), as well as in arid soil (by 1.6 times). The values of the following parameters significantly decreased in the conditions of the applied factors: the number of ammonifiers under low-level cadmium stress (by 3 times) and moderate soil acidity (by 5 times), cellulolytics in response to soil acidity (by 2.5 times) and under drought (by 1.7 times), urease activity in moderately acidic soil (by 1.7 times). In addition, the toxicity index for moderately acidic soil in the test for P. caudatum increased by 1.4 times.

Keywords

• soil models
• cadmium
• lack of moisture
• bioassay
• eco-trophic groups of microorganisms