Determination of the level of toxicity of the soils of recreational areas of Odessa city by biotesting methods

Abstract

The aim of the research – assessment of the level of chemical contamination of soils with heavy metals (Cd, Pb, Cu, Zn) and assessment of the toxicity of the soils of the recreational areas of Odessa as an indicator of unfavorable effect on the health of the population by the integral method of analyzing the quality of the environment object - the biotesting method, during which laboratory standardized test objects are used.Materials and methods. In this research biotesting of different soil samples was done to determine their phytotoxicity according to SSU ISO 11269-1: 2004 and SSU ISO 11269-2: 2002. The content of mobile forms of heavy metals Cd, Pb, Cu, Zn was determined according to SSU 4770.3: 2007, SSU 4770.9: 2007, SSU 4770.6: 2007, SSU 4770.2: 2007 with ammonium acetate buffer pH 4.8 on an atomic absorption spectrophotometer AAS 115. Also determined: the content of humus according to Tyurin (SSU 4289: 2004), nitrogen by nitrifying ability (GOST 26951-86), phosphorus and potassium according to Machigin (SSU 4114-2002); pHN2O (SSU 8346: 2015), the composition of the salt extract (according to SSU 7943: 2015, SSU 7908: 2015, SSU 7909: 2015, SSU 7944: 2015, SSU 7945: 2015); granulometric composition according to Kaczynski (SSU 4730: 2007); the composition of the absorbed bases Ca, Mg, Na (according to GOST 26487-85, SSU 7912: 2015).Results. Soils of the coastal slopes and the largest parks of Odessa, which are located in the areas of influence of highways different in traffic intensity and load, was selected as the objects of the research. In the key areas 8 full-profile soil sections and two diggings were laid according to generally accepted methods. In recreazems, the maximum permissible concentration of Zinc content was found to be three times higher (key areas 14-PP, section P9), 74 % of the selected samples had a very high level of Lead content, the maximum permissible concentration was exceeded. Exceedance of the maximum permissible concentration of Cadmium and Copper was not detected. In the research soft wheat seeds Triticum aestivum, Antonovka sort and barley Hordéum vulgáre, Dostoiniy variety, was selected as test cultures, test reactions in response to anthropogenic impact (laboratory germination, vigor, length of underground and aboveground part of seedlings) were recorded. The influence on morphological and physiological characteristics of test cultures, which are shown in inhibition of plant, yellowing elevated part of some test cultures was revealed. The toxicity of the soils, that was studied for growth inhibition of the aboveground part is assessed by phytotoxic activity mainly as highly toxic (Іс = 64-72 %). According to growth inhibition of the underground part of wheat is moderately toxic (Ik = 48-58 %). With regard to barley, a non-toxic effect by phytotoxic activity was revealed (Ic = 27-44 % and Ik = 39-49 %), which is indicative of the greater durability of barley seeds to contamination by heavy metals. When determining soils toxicity, the most indicative is the use of wheat in biotesting compared to barley.Conclusions. Soils according to the mean values of growth inhibition indices have the following toxicity: recreazems (Ic = -65 %, Ik = -55 %) - hillozems (Ic = -64 %, Ik = -57 %). Recreazems, in which an excess of maximum permissible concentration of Zinc was found (4 times more in the Victory park, 2 times in “Airport’s”, 1.5 times in parks “named after M. Gorky” and "named after T. Shevchenko"), and of Lead (6 times more in the park “Dukivskiy Sad”), have the highest indicators of phytotoxicity of aboveground part of wheat and are assessed as highly toxic (Ic = 64-72 %). It was revealed that the high content of nutrients in the soils of parks (recreazems) does not eliminate the toxic effects of heavy metals