Acid-volatile sulphide (,4VS) was measured at regular
positions along eight transects through a mangrove forest
in the Brisbane River, Queensland, ,4ustralia. Concentrations
ranged from 0.33 to 22.61 wnol S g-t sediment dry
weight. There was no correlation between A VS concentration
and the proportion of clay-sand in the sediment, but
sediments with high ,4 VS concentrations tended to contain
more water (r, = 0.42; p = 0.01). A VS concentrations
were used to assess the potential bioavailability of the
sediment heavy metal burden. The spatial variability of
potential bioavailability was high and depended to a great
extent on which metals were considered as part of the
,4 VS complexing system. It is suggested seasonal variations
would further increase the observed variability in
bioavailability. This variation should be taken into account
when monitoring and assessing long-term trends in sediment
toxicity. Copyright © 1996 Elsevier Science Ltd