Bioavailable metals in sediments: a partial HCl extraction procedure

So far the most commonly adopted analytical method employed for assessments of metal contamination in marine sediments has involved total or pseudo-total digestions with concentrated strong acid. In turn, partial extractions are an attractive alternative because they target the more chemically-reactive or labile fractions of the sediment containing metals, and they are reported to closely correlate with the bioavailable fraction. Different partial extraction methods with nitric, hydrochloric and acetic acids been used at a variety of concentrations, reaction times, and temperatures. We chose hydrochloric acid (HCl) because is a strong acid that will attack key labile phases in the sediment matrix, and is also efficient at decomposing labile organic phases and amorphous sulphides that control metal bioavailability in anoxic and partially oxidized sediments [3]. The aim of this research is to first evaluate the effect of reaction time on the 1M HCl extraction efficiency of 10 metals over at two different reaction times (4 and 24 h) in contaminated sediments, and to compare bioavailable vs total metal content obtained with microwave-assisted digestion.