Sono-extraction as a pretreatment approach for the screening evaluation of element mobility of sediment samples

Abstract

Application of economically important and time saving pretreatment for the screening element mobility evaluation of contaminated sediments is presented. Ultrasonically-assisted single-step extraction (USAE) was carried out by EDTA solution. The extraction time of USAE was optimized and obtained results were compared with results estimated by conventional (EDTA extraction) and by sequential extraction (modified BCR protocol). The original three step BCR protocol was modified by addition of the first step (water leaching) and the fifth step, total digestion of sediment residue (acid mixture with HF). Zn, Cu and Pb have been determined in extracts by ICP-OES. Good conformity of the ultrasonically-extracted element contents and sum of contents, extracted during first three steps (water-soluble, acid-extractable, reducible - i.e., the most mobile fractions) of sequential extraction, was found. The sono-extraction reduced operating time of the first three steps of sequential extraction from 48 h to 15 min. Thus, USAE can serve as a rapid screening assessment of the mobile and potentially mobile element portions in sediments and other similar solid state environmental media. Analytical quality control was realized by comparison of the sums of element contents obtained at individual (five) extraction steps. Total element contents were also determined by an independent method (XRF).