title: Novel Speciation Method Based on Diffusive Gradients in Thin-Films for in Situ Measurement of Cr(VI) in Aquatic Systems.
abstract: Hexavalent chromium (Cr(VI)) is much more toxic and mobile than the trivalent species (Cr(III)) and consequently, in situ monitoring of Cr(VI) can improve the understanding of Cr biogeochemistry and toxicity in ecosystems. The passive diffusive gradients in thin-films (DGT) technique is a powerful tool for determining metal(loid) speciation, but a binding phase that absorbs only one specific species of Cr is needed. N-Methyl-d-glucamine (NMDG) functional resin was incorporated into the DGT binding phase for selective measurement of Cr(VI). This NMDG-DGT sampler exhibited a theoretically linear accumulation of Cr(VI), with negligible accumulation (<5%) of Cr(III), even after 72 h deployment. The good prediction of Cr(VI) concentration in synthetic freshwater with NMDG-DGT, even in the presence of 10-time more Cr(III), further indicated the sampler's reliability in selective detection of Cr(VI). Moreover, its high capacity for Cr(VI), which exceeded 230 μg cm(-2), facilitates measurement of Cr(VI) in both uncontaminated natural waters and in slightly and heavily contaminated (ppm level) waters. Field deployment of the NMDG-DGT sampler in such waters allowed accurate measurement of time-averaged Cr(VI) concentration, indicating its robustness for in situ measurements of Cr speciation and its potential for further application in the risk assessment of Cr.
authors.affiliation: State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University , Nanjing, Jiangsu 210023, China.
authors.forename: Yue
authors.initials: Y
authors.lastname: Pan
authors.affiliation: State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University , Nanjing, Jiangsu 210023, China.
authors.forename: Dong-Xing
authors.initials: DX
authors.lastname: Guan
authors.affiliation: State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University , Nanjing, Jiangsu 210023, China.
authors.forename: Di
authors.initials: D
authors.lastname: Zhao
authors.affiliation: State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University , Nanjing, Jiangsu 210023, China.
authors.forename: Jun
authors.initials: J
authors.lastname: Luo
authors.affiliation: Lancaster Environment Centre, Lancaster University , Lancaster LA1 4YQ, United Kingdom.
authors.forename: Hao
authors.initials: H
authors.lastname: Zhang
authors.affiliation: Lancaster Environment Centre, Lancaster University , Lancaster LA1 4YQ, United Kingdom.
authors.forename: William
authors.initials: W
authors.lastname: Davison
authors.affiliation: State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University , Nanjing, Jiangsu 210023, China.|Soil and Water Science Department, University of Florida , Gainesville, Florida 32611, United States.
authors.forename: Lena Q
authors.initials: LQ
authors.lastname: Ma
mesh_terms: D002681:China; D002857:Chromium / Q000032:analysis*; D004058:Diffusion; D005618:Fresh Water / Q000737:chemistry; D005782:Gels / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008536:Meglumine / Q000737:chemistry; D008670:Metals; D009994:Osmolar Concentration; D015203:Reproducibility of Results; D014867:Water; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D005782:Gels; D008670:Metals; D014874:Water Pollutants, Chemical; D014867:Water; D002857:Chromium; C074702:chromium hexavalent ion; D008536:Meglumine