Bioavailability and metabolism in a soil-crop system compared using DGT and conventional extraction techniques. (September 2019)

• Record Type: Journal Article
• Authors: Li, Yanying; Rothwell, Shane; Cheng, Hao; Jones, Kevin C.; Zhang, Hao
• Is Part Of: Environment international. Volume 130(2019)
• Publication Date: 2019-09
• Subjects: Environmental protection -- Periodicals; Environmental health -- Periodicals; Environmental monitoring -- Periodicals; Environmental Monitoring -- Periodicals; Environnement -- Protection -- Périodiques; Hygiène du milieu -- Périodiques; Environnement -- Surveillance -- Périodiques; Environmental health; Environmental monitoring; Environmental protection; Periodicals; 333.705
• DOI: 10.1016/j.envint.2019.104924
• Languages: English
• ISSNs: 0160-4120

Abstract

Abstract: Traditional extraction methods (soil solution and solvent extraction) are simple to use and conventionally employed to assess pesticide chemical form and bioavailability in soils. However, whilst convenient for regulatory testing, it has been suggested that these approaches may be too crude or are poor predictors of bioavailability, due to their arbitrary original development to detect 'total' concentration using exhaustive extraction. The diffusive gradients in thin films (DGT) technique has been widely used to measure chemical speciation in situ and shown to reliably predict bioavailability of a range of contaminants (e.g. heavy metals, radionuclides, nutrients) in soil systems, because it dynamically samples contaminants from/re-supplied to the soil solution phase. Experiments were therefore conducted with 5 soils of different properties to compare DGT and the two conventional extraction approaches for sampling atrazine (ATR) and its metabolites from soils and for predicting their uptake by maize tissues. After 23 days aging, a large proportion of total ATR was still available for solvent (acetonitrile) extraction and the major constituent in soils was parent ATR. The best correlations of total ATR concentrations in maize and total ATR measured in soil were with DGT and soil solution measurements. This is encouraging, in jointly supporting one of the established methodologies traditionally used in pesticide testing (i.e. soil solution) and a widely used method (i.e. DGT), which has been validated previously for a range of contaminants. The poorer performance of solvent extraction (a procedure widely used for pesticide testing) is perhaps to be expected, given that solvents will not truly mimic the conditions encountered in soil-plant systems. Graphical abstract: Unlabelled Image Highlights: DGT and two extraction approaches for sampling pesticides from soils are compared. This is the first research on bioavailability of organic compounds in soils using DGT. DGT and soil solution extracts predict bioavailable atrazine taken up by maize. Solvent extraction will not mimic conditions encountered in soil-plant systems. DGT may aid contaminated land assessment or pesticide risk assessment testing.