Deriving site-specific soil clean-up values for metals and metalloids: Rationale for including protection of soil microbial processes

• Published in: Integrated environmental assessment and management 2014-07, Vol.10 (3), p.388-400
• Main Authors: Kuperman, Roman G, Siciliano, Steven D, Römbke, Jörg, Oorts, Koen
• Format: Article
• Language: English
• Subjects: Animal, plant and microbial ecology; Animals; Applied ecology; Bioavailability; Biological and medical sciences; Cleaning; Conservation, protection and management of environment and wildlife; Derivation; Ecological risk assessment; Ecology; Environmental assessment; Environmental Impact Assessment; Environmental management; Environmental protection; Environmental Restoration and Remediation - standards; Functionals; Fundamental and applied biological sciences. Psychology; Groundwater; Integrated environmental assessment; Invertebrates - drug effects; Jurisdiction; Metal; Metalloids; Metalloids - standards; Metalloids - toxicity; Metals; Metals, Heavy - standards; Metals, Heavy - toxicity; Microbial contamination; Microbial processes; Microorganisms; Nutrient cycles; Plants - drug effects; Redundancy; Risk Assessment; Soil; Soil (material); Soil chemistry; Soil contamination; Soil fertility; Soil improvement; Soil Microbiology; Soil microorganisms; Soil Pollutants - standards; Soil Pollutants - toxicity; Soil pollution; Soil structure; Soil testing; Special Series: Ecological Soil Clean-up Values for Metals; Guest Editor: Anne Fairbrother; Test methods; Thresholds; Toxicity; Toxicity testing; Toxicity tests; Water purification
• ISSN: 1551-3777; 1551-3793
• DOI: 10.1002/ieam.1513

ABSTRACT Although it is widely recognized that microorganisms are essential for sustaining soil fertility, structure, nutrient cycling, groundwater purification, and other soil functions, soil microbial toxicity data were excluded from the derivation of Ecological Soil Screening Levels (Eco‐SSL) in the United States. Among the reasons for such exclusion were claims that microbial toxicity tests were too difficult to interpret because of the high variability of microbial responses, uncertainty regarding the relevance of the various endpoints, and functional redundancy. Since the release of the first draft of the Eco‐SSL Guidance document by the US Environmental Protection Agency in 2003, soil microbial toxicity testing and its use in ecological risk assessments have substantially improved. A wide range of standardized and nonstandardized methods became available for testing chemical toxicity to microbial functions in soil. Regulatory frameworks in the European Union and Australia have successfully incorporated microbial toxicity data into the derivation of soil threshold concentrations for ecological risk assessments. This article provides the 3‐part rationale for including soil microbial processes in the development of soil clean‐up values (SCVs): 1) presenting a brief overview of relevant test methods for assessing microbial functions in soil, 2) examining data sets for Cu, Ni, Zn, and Mo that incorporated soil microbial toxicity data into regulatory frameworks, and 3) offering recommendations on how to integrate the best available science into the method development for deriving site‐specific SCVs that account for bioavailability of metals and metalloids in soil. Although the primary focus of this article is on the development of the approach for deriving SCVs for metals and metalloids in the United States, the recommendations provided in this article may also be applicable in other jurisdictions that aim at developing ecological soil threshold values for protection of microbial processes in contaminated soils. Integr Environ Assess Manag 2014;10:388–400. © 2014 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals, Inc. on behalf of SETAC. Key Points This article presents an overview of relevant test methods for assessing microbial functions in soil, and examines soil microbial toxicity data sets for Cu, Ni, Zn, and Mo that have been incorporated into regulatory frameworks High natural spatial and temporal variat