Ecological and toxicological assessment of the influence of the chemical enterprise on soil

Abstract

Technogenic pollution of the territory firstly leads to decrease of productivity of the land, since the main part of the technogenic loading, as a result of such pollution, assumes to the soil and vegetation. Soils those have been contaminated are characterized by changed structural and physical-and-chemical properties, which does not allow them to be used for economic purposes. To detect the technogenic loading on the soil as a result of the chemical plant operation, soil quality studies were carried out using the bio-testing method. The most informative data towards ecological danger of ecosystem pollution is the results of the determination of phytotoxicity for soil organisms. Such information can be obtained by an integral assessment of the biological usefulness of the habitat of organisms using the bio-testing method, which provides registration in controlled, standard conditions of the corresponding reactions of test organisms to the toxic effects of ecologically hazardous chemical compounds and their mixes. The following higher plants were selected as test cultures: Raphanus sativus L., Hordeum vulgare L. and Triticum aestivum L. As the test-response of higher plants, the energy of seed germination, the length of the sprout and the length of the root were taken into account. Four zones were selected for the research. The largest difference between the values of germination energy between control and experiment was observed on the results of a test-response to Hordeum vulgare L. in a sample of soil from zone Nr 4. The indicator of the toxic effect detected on the territory of zone Nr 4 - 43,64% reduction in the length of the roots relative to the control; 33.81% reduction in the length of the germs relative to the control based on the results of the test-response to Hordeum vulgare L. The soil sample from the zone Nr 1 showed no toxic properties in any test reaction (6.32% decrease in root length relative to control one, 5.68% reduction length of germs relative to the control one based on the results of the test reaction on Raphanus sativus L. Sample of soil from zone Nr 2 did not show toxicity (-45.26% decrease in root length relative to control one and 8.61% decrease in germination length relative to control one revealed by the results of the test-response to Raphanus sativus L. Soil samples from zone Nr 3 also showed no toxicity (3.83% decrease in root length relative to control and 11.02% reduction in germination length relative to control revealed by test-reaction results on Raphanus sativus L. The table value of the Student's criterion for the probability level is P = 0.5 and the number of measures of freedom 58 is 2.01. The calculation of the actual value of Student's criterion for the length of the roots (2.68) and the germs (2.05) showed an excess of the table value based on the results of the test-response on Hordeum vulgare L. in the soil sample from zone Nr 4, what confirms the presence of toxic properties of the soil. In order to assess the risk of soil contamination, the "measure of soil contamination" indicator was used in accordance with defined levels of inhibition of growth processes, the quantitative characteristics of which are expressed by the soil contamination coefficient, while the soil contamination coefficient is differentiated according to the levels of inhibition of growth processes. According to the calculated data, in the sample Nr 4, the phytotoxic factor or percentage reduction in the length of the roots relative to the control is 43.64% based on the results of the test-response to Hordeum vulgare L. By level of contamination, the soil is moderately polluted, belongs to the III class of quality and shows the measure of contamination of 1,3. Soil samples №1, №2 and №3 showed no toxicity (А˂20), i.e., they are non-contaminated and belong to the I class of quality. Therefore, for the integrated assessment of soil quality, in addition to chemical indicators, it is recommended to use integral indicators, in particular phytotoxicity of the soil, which characterizes the biological usefulness of the habitat of organisms.