The Soils of the Botanical Garden of St. Petersburg State University (Saint Petersburg, Russia)

Under intensive urbanization, botanical gardens soils can serve as reference plots for urban areas, reflecting both natural (pedogenic) and anthropogenic factors of soil formation. In this context, historical and archeological information on the Botanical garden of Saint Petersburg State University (BG SPbU) is presented. For the first time, morphological, physicochemical, and ecotoxicological characteristics of the BG SPbU soils are assessed using full-profile soil pits. The ecological features of the BG SPbU are noted, and the specific structure of the upper soil layer (up to 2 m) is examined. The physicochemical properties of the BG SPbU soils are consistent with the optimal levels for green spaces of the highest (I) category. In the 0–90 cm layer of the studied soil pits, elevated concentrations (relative to Russian regulatory standards) of toxic trace elements (lead, zinc, arsenic) are found. No signs of vegetation stress were detected during the survey. At the same time, the measured concentrations of Pb, Zn, and As exceed the Russian MPC (maximum permissible concentrations) and APC (approximate permissible concentrations) for heavy metals. These exceedances provide important information for further monitoring and decision-making regarding urban pollution regulation, and contribute to the discussion on revising the MPC and APC values in line with international standards. The results can be used to optimize management practices for green spaces of the BG SPbU and can also be incorporated into the long-term urban environmental monitoring program initiated in Saint Petersburg in 1991.