The Clybucca Wetlands is a depositional environment on the lower Macleay floodplain in New South Wales, Australia. Arsenic- and antimony-bearing mine waste from upstream historic mining activities is the main source of toxic metalloids in surface soils at the Clybucca Wetlands1. However, it is unknown whether the Clybucca Wetlands behave as a sink or seasonal source for As and Sb, considering seasonal redox transitions may influence metalloid re-mobilisation. Here, we investigate (i) As and Sb susceptibility to partition to the aqueous phase with the drying of waterlogged soil and (ii) identify predictors of As and Sb geochemical mobility based on spatial distribution patterns. Preliminary data for this study shows that elevation, a driver of inundation frequency, is negatively correlated (r2=0.63) with near-total Sb concentrations in soil which indicates that Sb remains in low elevation areas post-deposition. In contrast, concentrations of As in soil are not correlated with elevation (r2=0.01) which could be due to soil water leaching under reducing conditions. We hypothesise that Sb will show greater susceptibility to partitioning to the aqueous phase as soil progressively oxidises, in comparison to As. This hypothesis will be tested by time series near-total concentration and 1:5 H2O extraction data over a four-month soil incubation. The Clybucca Wetlands are undergoing remediation due to exposed acid sulfate soils2, and a better understanding of potential As and Sb mobilisation from low pH soils to surface water is relevant to on-site and downstream water quality.