Comparison of Two Integrated Biotic Indices in Assessing the Effects of Humic Products in a Model Experiment

Abstract

The descriptive ability of two integral biotic indices obtained from laboratory experimental data focused on estimating the effects of humic products (HPs) on the microbiota under conditions of copper contamination in a model soil substrate is evaluated. The “Standard Soil” prepared from sand, kaolin, and peat (ISO 11268-1) as recommended for the assessment of biological effects was used. To summarize the results of ecotoxicological studies of Cu-polluted samples (660 mg Cu/kg) and to provide the integral estimation of HPs impact on the microbiota, two statistical models were used: the Harrington’s desirability function D and the integrated parameter of the soil microbial system sustainability G (ratio of biodiversity to instability) using multisubstrate testing. The indices obtained based on two sets of multidimensional data were compared in their descriptive ability when estimating the detoxifying efficiency of HPs. It was found that HPs mainly stimulate multispecies bacterial complexes, while the test cultures representing higher plants and algae are less sensitive to their impact. Three of the five studied HPs showed a pronounced detoxifying effect and improved the state of the studied system. Both integral biotic indices—the generalized Harrington desirability function D and the General sustainability parameter of the system G—demonstrated a similar effect vector. For the purpose of environmental regulation, the use of the integrated approach based on a generalized desirability function could be recommended due to its higher completeness and reliability of the system of biotic indicators.