Ultrasound-Assisted Extraction for the Evaluation of Element Mobility in Bottom Sediment Collected at Mining and Smelting Pb–Zn Ores Area in Poland

Abstract.

The current BCR procedure for metal fractionation recommended by the Standard Measurement and Testing Programme requires rather time-consuming sample pretreatment. Ultrasonic energy seems to be an attractive alternative for leaching metal from solid samples into a liquid extractant phase. This study aims at optimizing ultrasonic extraction in order to replace the BCR method of leaching using acetic acid and to apply the procedure of assessing element mobility in bottom sediment rich in moderately soluble carbonate minerals. The application of ICP-MS allowed the determination of As, Cd, Cr, Cu, Pb, Ni, Tl and Zn in extracts, in a wide range of concentration without any special treatment. Finally, 40’min extraction in an ultrasonic bath was proposed for evaluation of the mobile fraction of As, Cd, Cr, Cu, Pb and Zn as an assessment of environmental risk. The recovery of the ultrasound-assisted extraction in comparison to the shake-filter method, as applied in the common BCR procedure, was slightly higher than 100% for As, Cr and Pb, reasonably high (about 70%) for Cd, Zn and Cd, but did not exceed 21% for Tl. Also, the mobility and extractability (relative mobility) of the studied elements from sediment collected over one year were compares. According to the results obtained after 40’min of ultrasound-assisted extraction it can be concluded that mobility did not change over one year for Cr, Cu, As, Cd, Ni and Tl, but noticeable differences for Zn and Pb were observed. The total content of all studied elements was almost the same in samples taken in the years 2003 and 2004, respectively.