A COMPARISON OF SAMPLE HANDLING AND ANALYTICAL METHODS FOR DETERMINATION OF ACID VOLATILE SULFIDES IN SEDIMENT

Proper sample storage and analytical techniques are required when anal yzing anoxic sediment for acid volatile sulfide (AVS), because a chang e in redox state may alter sediment parameters. The goal of this study was to determine the optimum sample handling, storage, and analytical techniques to adopt when determining AVS concentrations in sediment. To determine the correct handling and storage protocols for use with a noxic sediment, samples of three different AVS levels were manipulated under a combination of the following handling and storage plans: hand led on benchtop or under nitrogen atmosphere; preserved with zinc acet ate (ZnAc) or not preserved, and stored at 4 degrees C or frozen (< - 20 degrees C). The data indicate that sulfide levels are best maintain ed when samples are handled under a nitrogen atmosphere, stored-at 4 d egrees C or frozen, and analyzed within 2 weeks of collection. To dete rmine the best analytical procedure for the determination of AVS in se diment, the following methods were compared: colorimetric, gravimetric , ion-selective electrode, and photoionization detection. The colorime tric method was preferred.