Measurement of labile arsenic speciation in water and soil using Diffusive Gradients in Thin-films (DGT) and X-ray Absorption Near Edge Spectroscopy (XANES)

Huynh, Trang, Harris, Hugh, Zhang, Hao and Noller, Barry (2015) Measurement of labile arsenic speciation in water and soil using Diffusive Gradients in Thin-films (DGT) and X-ray Absorption Near Edge Spectroscopy (XANES). Environmental Chemistry, 12 2: 102-111. doi:10.1071/EN14047


Author Huynh, Trang
Harris, Hugh
Zhang, Hao
Noller, Barry
Title Measurement of labile arsenic speciation in water and soil using Diffusive Gradients in Thin-films (DGT) and X-ray Absorption Near Edge Spectroscopy (XANES)
Journal name Environmental Chemistry   Check publisher's open access policy
ISSN 1448-2517
1449-8979
Publication date 2015-02-17
Sub-type Article (original research)
DOI 10.1071/EN14047
Open Access Status
Volume 12
Issue 2
Start page 102
End page 111
Total pages 10
Place of publication Collingwood, VIC, Australia
Publisher C S I R O
Collection year 2016
Language eng
Abstract The Diffusive Gradients in Thin Films technique is an in-situ sampling technique that can concentrate labile arsenic species from solution. This technique has provided a way to measure the total concentration of labile arsenic, which may be toxic in the environment. A previous study measured arsenic speciation in the solution extracted from the FB-DGT gel deployed in water using coupled high-performance liquid chromatography and hydride generation atomic fluorescence spectrometry (HPLC-HG-AFS). However, the extent of change in arsenic speciation during the extraction process is unknown. By identifying the arsenic species in the FB-DGT gel directly, using X-ray absorption near edge spectroscopy (XANES) fitting with model arsenic compounds, we obtain a better understanding of the ability of FB-DGT to measure labile arsenic species in solution. The results presented herein confirm that FB-DGT accumulated labile inorganic and methylated arsenic species. Arsenic species bound to the FB-DGT gel were stable for up to two weeks following deployment. However, caution should be applied when interpreting the proportion of As species measured by HPLC-HG-AFS in solution extracted from FB-DGT because the distribution of arsenic species in extracted solutions was found to be modified by the extraction process. Some (~ 20 %) of arsenate was converted to arsenite, and a significant amount (~ 25 %) of dimethylarsinic acid (DMAsV) was converted to monomethylarsonic acid (MMAsV) or arsenate (AsV). Only inorganic arsenite (iAsIII) was stable during the extraction process. These findings suggested that, based on the XANES measurement, although As species were quantitatively accumulated in the FB-DGT gel, the FB-DGT technique was still unsuitable for studying As speciation. This is because the XANES technique is not suitable for routine measurement and changes in arsenic speciation were observed to occur during gel extraction, prior HPLC-HG-AFS measurement.
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ
Additional Notes Published online: 17 February 2015.

Document type: Journal Article
Sub-type: Article (original research)
Collections: Centre for Mined Land Rehabilitation Publications
Official 2016 Collection
 
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Created: Tue, 26 Aug 2014, 15:05:28 EST by Dr Trang Huynh on behalf of Centre For Mined Land Rehabilitation