Development of regional standards for pollutants in the soil using biological parameters

The development of regional or local maximum permissible concentration (MPC) for a pollutant in the soil requires the field or laboratory simulation of pollution. The experimental design should include the control (uncontaminated soil with the background concentration of the pollutant) and at least three treatments with different pollutant concentrations in the range between 2 and 10 background values. Experiments are performed in at least three replicates. Soil samples are taken 30 days after contamination. In each soil sample, six biological parameters are determined: total bacterial abundance, Azotobacter abundance, catalase activity, dehydrogenase activity, cellulolytic activity, and radish root length. Analyses are made in at least six replicates. From these biological parameters, the integrated biological index (IBI) of soil is calculated. For this purpose, the value of each parameter in the uncontaminated soil is taken as 100%, and its values in the contaminated soils are expressed as percentages. The mean values of six parameters for the contaminated treatments are determined. The obtained IBI values are expressed in percentages of the background. Then, a regression equation describing the decrease in IBI values as a function of pollutant concentration in the soil is derived. The pollutant concentration corresponding to the IBI decrease by 10% of the control, which indicates a disturbance of the holistic biogeocenotic functions of soil, is calculated from this equation.