Classification and Modelling of Nonextractable Residue (NER) Formation of Xenobiotics in Soil – A Synthesis

Abstract

This review provides a comprehensive overview about nonextractable residue (NER) formation and attempts to classify the various types. Xenobiotic NER derived from parent pesticides (or other environmental contaminants) and primary metabolites sorbed or entrapped within the soil organic matter (Type I) or covalently bound (Type II) pose a considerably higher risk than those derived from productive biodegradation. However, biogenic nonextractable residues (bioNER) (Type III) resulting from conversion of carbon (or nitrogen) from the compounds into microbial biomass molecules do not pose any risk. Experimental approaches to clearly distinguish between the types are provided, and a model to prospectively estimate bioNER formation in soil is proposed.

KEY WORDS:

• pesticides
• xenobiotics
• non-extractable residues (NER)
• NER xenobiotic/biogenic/classification
• fate analysis
• biodegradation
• soil organic matter
• risk assessment
• sequestration
• aging
• modelling

Additional information

Funding

This study was financially supported by the Helmholtz Centre for Environmental Research UFZ, by the German Research Council (DFG, No 980/1-1 and Scha 390/13-1), and by the European Commission funding of the RaiseBio project (Contract: MEST-CT- 2005-020984) under Human Resources and Mobility Activity (6th Framework programme), in particular, the fellowship of K. M. Nowak, and the MagicPAH project (Contract: 245226).