The high variability reported here for Pb in the Pierreville sediment was also observed during
preliminary experiments, despite repeated grinding of the sediment in an effort to improve its
homogeneity. Similar problems of low reproducibility for “acid leachable” (pH 1.5) lead in suspended sediments have been reported (40) and were attributed to the presence of relatively
large (>8 pm) lead-rich particles originating from aerosols produced by the combustion of leaded gasolines; such particles are observed close to highways (41). Wagemann et al. (30) also reported scattered lead results following leaching of sediments and suspensions with saturated EDTA or 0.1 M
HC1 solutions.