Assessment of the health of soils polluted by municipal solid waste landfill

• Solid municipal waste landfills are poisoning the soil with heavy metals. • Exceeding the permissible concentrations of Zn, Cu Cr, Ni, As, Pb has been established. • The most informative and sensitive indicator in biodiagnostics of municipal solid waste landfill soil health is catalase activity. The number of landfills for municipal solid waste is growing every year. The aim of our study is to assess the health of soil polluted by municipal solid waste landfill. 13 points were examined: municipal solid waste landfill (No. 1–8), abandoned field (No. 9–11) and cropland (No. 12–13). To assess soil pollution, the following indicators were calculated: the total pollution index (Zc), pollution load index (PLE), potential ecological risk (PERI). Geobotanical description of the sites was investigated, physical, chemical (pH, the content of easily soluble salts, humus content, the gross content of heavy metals), and biological (the total number of bacteria, the activity of catalase, invertase, and dehydrogenases, the length of roots and shoots of radish) indicators were studied. The integral indicator of the biological state of the soil (IIBS) was used to combine different biological indicators. To confirm the reliability and analysis of the obtained results, statistical methods of univariate analysis of the Tukey's post-hoc criterion, correlation analysis using the Spearman's criterion and multivariate factor analysis using the principal components method were used. According to the MPC/APC ratio, soil pollution with Cr exceeded the control by 18 times, Ni — by 4 times, Cu — by 45 times, Zn — by 51 times, As — by 5 times, and Pb — by 6 times. The data of the Z c and PLE shows a high degree of pollution by heavy metals and an extremely high level of PERI the landfill area. There was a significant decrease in the activity of catalase and invertase and the total number of bacteria by 10–82%. The most informative and sensitive biological indicator was catalase activity. The data obtained by the study shows that the indicators of catalase activity, root length, and the total number of microorganisms can be used in monitoring and diagnosing the health of soils under solid waste landfills and the surrounding area.