Description
The BCR sequential extraction procedure1 is widely used to determine the operational speciation of potentially toxic elements (PTE) in soils and sediments. When applying the approach, a dichotomy exists between maintaining a sample’s natural speciation, and pre-treating the sample to make it stable and more suitable for standard laboratory operations such as sieving, cone-and-quartering etc. Sample drying in particular has been reported to cause redistribution of analytes to more readily extractable forms2, 3.In order to assess the effects of freeze and air drying on the operational speciation of PTE in sediment with different amount of the nominal target phases (carbonate (CO32-), iron(hydr)oxides (FeOOH) and organic matter (OM)), the modified BCR sequential extraction procedure was applied to sediments collected from the catchment of the River Derwent (an area impacted by historical mining and smelting) and River Wear (an area impacted by historical lime stone mining). The pH, cation exchange capacity (CEC), CO32-, FeOOH and OM content of the sediments were determined. A Thermo Scientific iCE 3000 SERIES AA spectrometer was used to measure Mg and Fe following the British standard procedure for the determination of CEC and FeOOH in soil. Sediments were analysed as received, freeze-dried and air-dried. Extracts were analysed for As, Cd, Cu, Fe, Mn, Ni, Pb, U and Zn using Agilent 7700x ICP-MS instrument.
Freeze drying significantly transferred Cd, Fe, Mn, Ni and Zn to forms inaccessible to aqua regia digestion. Different changes in operational speciation occurred for different PTE at 95 % confidence level. No sample pre-treatment procedure preserved the speciation of the PTE intact. Air drying is recommended because it is more feasible, and had less effect on the operation speciation of PTE compared to freeze drying pre-treatment.
1. G. Rauret, J. F. Lopez-Sanchez, A. Sahuquillo, R. Rubio, C. Davidson, A. Ure and Ph.Quevauviller, J. Environ. Monit., 1999, 1, 57 - 61.
2. E. Hiller and M. Sutriepka, J. Hydrol. Hydromech, 2008, 56, 45 -58.
3. T. Hjorth, Analytica Chimica Acta, 2004, 526, 95-102.
| Period | 2018 |
|---|---|
| Event title | 10th Scottish Symposium on Environmental Analytical Chemistry |
| Event type | Conference |
| Location | Glasgow, United KingdomShow on map |