Guideline Values for the Content of Chemical Elements in Soils of Urban Functional Zones: A Review

The Russian soil quality assessment system, where the guideline values for the content of heavy metals and metalloids derived for arable lands (mostly, in terms of the general sanitary indicator of harmfulness) are applied to soils of the residential area and the protected area of water supply sources, can be updated using international experience, e.g., substantiation of generic values for urban functional zones since, with a few exceptions, the Russian soil quality guidelines are the same for all soils of the country. In order to assess the applicability of foreign approaches to Russian realities, we have thoroughly analyzed the original and most developed legislation systems of the soil quality control in cities of Germany, Canada, and the United States, as well as the systems of Australia, New Zealand, Republic of South Africa, and the countries of the European Union, where the values are land use specific. In this paper, we summarize the principles of soil quality assessment for the contents of chemical elements, brief the methodology used in different countries and the consequences of exceeding the standards, and highlight some clues for improving the Russian soil quality assessment system. The Russian soil quality assessment system can be improved and updated by substantiating (i) the land use specific standards for cities with the focus on actual subjects of standardization (the health of ecosystems, children, or adults); (ii) the standards for different geochemical environments taking into account the specific features of migration of substances; and (iii) the standards for the soil materials used to construct lawns and roadside areas. In addition, we suggest (i) developing a comprehensive system of management decisions for the case when soil quality standards are exceeded; (ii) legitimizing the concept of historical pollution that existed before the commencement of business activities; and (iii) establishing the minimum volume of soil and the depth or set of soil horizons to be remediated or removed due to pollution.