THE APPLICATION OF MICROWAVE-HEATING IN SEQUENTIAL EXTRACTIONS OF HEAVY-METALS IN ESTUARINE SEDIMENTS

Using a modification of the procedure elaborated by Tessier et al. (19 79) the conditions under which microwave heat was applied to perform s equential extractions of metals in estuarine sediments were evaluated. Necessary times were determined for the complete metal extractions an d substantial reductions in time were obtained in comparison with the traditional techniques, (from hours to minutes). The techniques were a pplied to two reference materials: MESS-1 and SEDIMENTO (a secondary s tandard prepared in our laboratory). The problems of methodology assoc iated with the use of microwaves are discussed, as well as the results obtained regarding the variability of the data of each fraction and t he percentages of recovery. The techniques were also applied to intert idal surface sediments of three northwestern Spanish estuaries. Percen tages of recovery are discussed as well as the relationship of the res ults to the physical/chemical variables of the medium.