SPATIAL AND SEASONAL-VARIATIONS OF ACID VOLATILE SULFIDE (AVS) AND SIMULTANEOUSLY EXTRACTED METALS (SEM) IN DUTCH MARINE AND FRESH-WATER SEDIMENTS

Within the framework of setting environmental quality criteria for cer tain heavy metals in sediment, Acid Volatile Sulphide (AVS) has been p roposed as the primary standardisation parameter in combination with t he amount of simultaneously extracted metals (SEM). From a series of t oxicity studies published in the literature, it was concluded that the SEM/AVS ratio is able to predict quite well the availability of vario us heavy metals for different organisms. Incorporation of the SEM/AVS ratio in deriving sediment quality criteria has been proposed, princip ally in the US. This study has been designed to investigate the applic ability of the AVS-concept in Dutch sediment quality criteria. Due to the dynamic behaviour of AVS especially in natural systems, knowledge with respect to spatial and seasonal variations of AVS and SEM levels is required for a proper application of the AVS-concept. AVS has been detected in 95% of the investigated sediment samples. The correspondin g SEM/AVS ratio was found to be smaller than one in 19 out of 21 sampl es. According to literature data, toxic effects from heavy metals are expected to be absent under these conditions. Hence, implementation of the AVS-concept in Dutch quality criteria seems to be justified regar ding our observations. However, seasonal variations in AVS and SEM con centrations were observed, which may lead to variations in metal avail ability for organisms during the year. Although the seasonal behaviour was different for various sediments, the corresponding SEM/AVS patter ns were found to be smalller than one in all cases. This observation i s very promising for further acceptance of the AVS-concept in setting quality criteria. (C) 1997 Elsevier Science Ltd.