Ecological State Assessment of Urban Soils by Bioassay

The aim of this study was to assess the ecological state of the soil of a megalopolis (St. Petersburg) located in the North-West of the Russian Federation using bioassay in order to create a set of the most sensitive biotests. For this, 4-year monitoring studies of the soil quality in different functional zones of the city were carried out using the bioassay, physicochemical, and chemical analyses. A set of express biotests that allow for an integral ecotoxicological assessment of urban soils was developed and tested for the first time. The developed block of biotests consists of test organisms that are representatives of the main levels of the trophic chain: higher plants (Triticum vulgare L.) for producers, hydrobionts (Paramecium caudatum) for consumers, and natural soil microbiocenosis for decomposers. All the test cultures revealed the toxicity of urban soils; they were characterized by different sensitivities to toxicants. Our result showed that a correct assessment of the ecological state of urban soils is possible on the basis of the combined use of eluate (water extract) and contact bioassays. Biotests make it possible to record negative phenomena in urban soils, which occur even under low human-induced loads. The research data confirm the necessity and effectiveness of the study of the soils' state using a battery of bioassays for inclusion in the monitoring system of urban soils.

Automated summary

The aim of this study was to assess the ecological state of the soil in a megalopolis using bioassay and develop a set of sensitive biotests for comprehensive ecotoxicological assessment. The results showed that the combined use of eluate and contact bioassays allows for accurate evaluation of the ecological state of urban soils, and biotests are valuable for monitoring negative phenomena in urban soils.