Background: Acid-volatile sulphides (AVS) and simultaneously extracted metals (SEM)
have been used as sediment quality criteria in both contaminated or non-contaminated sediments. The
AVS/SEM model is based on the criterion that metal toxicity is absent when the sum of the acid-labile
divalent metal concentrations ([ΣSEM]) is less than the concentration of acid-volatile sulphides ([AVS])
expressed as a molar ratio.
Method: The US EPA-recommended method for AVS extraction and determination uses 6 mol L-1
solution for 1 hour and NaOH solution to absorb the H2
S generated in the previous step. Sulphide ions
can be determined by different procedures, such as gravimetry, spectrophotometry and ion-selective
Results: The aim of this work was the use of microwave radiation as a fast alternative for the generation
S. For this procedure, a glass apparatus was developed, adapting a digestion tube that is generally
used in a focused microwave oven. The chemical extraction conditions were evaluated. A flow injection
analysis (FIA) system was applied to the determination of sulphide.
Conclusion: The developed procedure results in a total time for the AVS determination method that is
one-tenth of that of the recommended method (12 minutes compared to approximately 2 hours). The results
obtained show that AVS was accurately quantified in a range of 1.5 to µ290mol S g-1
< 13 %). Surficial and core sediment samples from several impacted areas were analysed by both the standard
(US EPA) procedure and the developed method, and no significant differences were observed.