SPATIAL-DISTRIBUTION OF ACID-VOLATILE SULFIDE CONCENTRATION AND METALBIOAVAILABILITY IN MANGROVE SEDIMENTS FROM THE BRISBANE RIVER, AUSTRALIA

Acid-volatile sulphide (AVS) was measured at regular positions along e ight transects through a mangrove forest in the Brisbane River, Queens land, Australia. Concentrations ranged from 0.33 to 22.61 mu mol S g(- 1) sediment dry weight. There was no correlation between AVS concentra tion and the proportion of clay-sand in the sediment, but sediments wi th high AVS concentrations tended to contain more water (r(s) = 0.42; p = 0.01). AVS concentrations were used to assess the potential bioava ilability of the sediment heavy metal burden. The spatial variability of potential bioavailability was high and depended to a great extent o n which metals were considered as part of the AVS complexing system. I t is suggested seasonal variations would further increase the observed variability in bioavailability. This variation should be taken into a ccount when monitoring and assessing long-term trends in sediment toxi city. Copyright (C) 1996 Elsevier Science Ltd