The Use of Lawn Grasses for Purification of Soil From Toxic Cr(VI)

Abstract

Background. Environmental pollution with toxic compounds poses a danger to nature and humans. Various technologies for soil purification from toxic metals are being developed. Objective. The work was aimed to study the possibility of lawn grass using for soil purification from Cr(VI). Methods. Plant seeds (Festuca rubra L. 45%, Festuca arundinacea Schreb. 25%, Lolium perenne L. 20%, Poa pratensis L. 10%) were sown in a container at 24 °C and grown for two months to obtain a lawn. K2CrO4 was added to the soil (400 g) (variants: 1.0 g, No. 1 and 2.5 g, No. 2) The following parameters were determined in two, five and ten days after Cr(VI) addition to the soil: the content of Cr(VI) in the roots, aerial part, and the soil; the coefficient of Cr(VI) content reduction; total content of aerobic heterotrophic microorganisms (CFU/g). Results. In 2 days after Cr(VI) adding the roots accumulated Cr(VI) in more significant amounts than the leaves (16.6 and 15 times in No. 1 and No. 2). In 5 days, an increase in Cr(VI) concentration in the plants was detected. Cr(VI) concentration in the soil decreased in 5 days by 45.8 and 13.57 times in variants No. 1 and No. 2, respectively. Inhibition of soil microorganisms growth was detected. CFU number in the control sample was 7.2×108, and in experimental variants No. 1 and No. 2 – 5×106 and 1×106, respectively. Conclusions. The addition of K2CrO4 inhibited the growth of soil microorganisms. Lawn grasses composition was successfully used for Cr(VI) extraction from the soil. A notable (13.8 and 9.3 times) reduction in Cr(VI) content in the soil was observed in two days. This reduction progressed greatly in five days as well (91.8 and 85.0 times). Cr(VI) was accumulated in the root system and the leaves of the plants. Thus, the selected grasses can be used in bioremediation technologies to purify contaminated soil.