Measuring ZnO nanoparticles available concentrations in contaminated soils using the diffusive gradient in thin-films (DGT) technique

• Published in: The Science of the total environment 2021-11, Vol.793, p.148654-148654, Article 148654
• Main Authors: Pouran, Hamid, Alkasbi, Mohammed, Lahive, Elma, Lofts, Stephen, Zhang, Hao
• Format: Article
• Language: English
• Subjects: Chelex; Contaminated soils; DGT; Dialysis membrane; Diffusive gradients in thin-films; Nanoparticles; Zinc oxide dissolution; ZnO NPs
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2021.148654

A major gap in understanding nanomaterials behaviour in the environment is a lack of reliable tools to measure their available concentrations. In this research we use diffusive gradients in thin films (DGT) for measuring concentrations of zinc oxide nanoparticles (ZNO NPs) in soils. Available nanoparticle concentrations were assessed by difference, using paired DGT devices with and without 1000 MWCO dialysis membranes to exclude NPs. We used ZnO because its toxic effects are accelerated through dissolution to Zn2+. Our test soils had different pH and organic matter (OM) contents, which both affect the dissolution rate of ZnO NPs. Woburn (pH ≈ 6.9, OM ≈ 1.8%) and Lufa (pH ≈ 5.9, OM ≈ 4.2%) soils were spiked to a single concentration of 500 mg of ZnO NPs per 1 kg of soil and the available concentrations of ZnO NPs and dissolved zinc were evaluated in 3, 7, 14, 21, 28, 60, 90, 120, 150 and 180 day intervals using DGT. The results showed that the dissolution of ZnO NPs, as well as the available concentrations of both dissolved and nanoparticulate Zn, was much higher in Lufa soil than in Woburn. This work demonstrates that DGT can be used as a simple yet reliable technique for determining concentrations of ZnO NPs in soils and probing its dissolution kinetics. [Display omitted] •We equipped DGT devices adding a 1000 MWCO DM to measure ZnO NPs in 2 test soils•During tests of 180 days ZnO NPs dissolution was much higher in low pH soil•Available concentrations of dissolved & ZnO NPs were also higher in the low pH soil•This is the 1st study probing in situ NPs dissolution kinetics in soils using DGT•DGT can be used to study in situ concentrations & dissolution kinetics of ZnO NPs