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© 2014 American Chemical Society. The mobility of groundwater and its reactivity with subsurface lithologies makes it an ideal medium for investigating both the mineralogy of the extensive volume of the rocks and soils that it comes into contact with, including the distribution of potential commodities, and the presence of contaminants. Groundwater grab sampling is potentially an effective tool for evaluating metal and metalloid concentrations but can suffer from poor replication and high detection limits. This study evaluates the diffusive gradients in thin films (DGT) technique to detect signatures of Au mineralization in groundwater, as well as associated pathfinder and potential contaminant elements (As and Sb). The DGT technique was modified for Au by evaluating a "gel-less" configuration, with diffusion onto an activated carbon binding layer being controlled by the 0.13 mm thick filter membrane (0.45 μm porosity) only, in order to increase sensitivity in quiescent solutions. Laboratory-based measurements indicated that the diffusive boundary layer (DBL) was ∼0.40 mm in thickness in quiescent solutions. The modified DGT samplers were then deployed alongside ferrihydrite DGT devices (fitted with 0.8 mm diffusive gels) to simultaneously measure Au, As and Sb in groundwaters surrounding a known arsenopyrite-hosted Au ore body. DGT-measured Au concentrations ranged from 2.0 ng/L to 38.5 ng/L, and were within a factor of 5 of grab sample concentrations. DGT-measured concentrations of As and Sb were above the detection limits, while grab sample concentrations of As and Sb were often close to or below detection. The DGT technique demonstrated methodological improvement over grab sampling of groundwater for the investigated elements with respect to sensitivity, replication, and portability, although DGT requires further evaluation in a wider range of groundwater environments and conditions.
|Number of pages||9|
|Journal||Environmental Science and Technology|
|Early online date||24 Sept 2014|
|Publication status||Published - Oct 2014|
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- 2 Finished
Environmental risk assessment of acid sulfate soil formation and pollutant generation in Swan Coastal Plain
Rengel, Z., Hinz, C. & Rate, A.
1/01/09 → 31/12/11
Evaluating a Biogeochemical Mechanism for Soil Anomaly Formation Using Diffusive Thin Fiom Samplers in Geochemical Exploration
Rate, A. & Radford, N.
1/01/08 → 31/12/11