Fig. 2. Changes in pH and dissolved arsenic over time in a sediment–water slurry. Slurry pH reached a steady state within 30 min; dissolved arsenic reached a steady state after approximately 20 h. The solid line indicates the remobilization expected from Step I of the fractionation scheme. Each point represents the average of three samples. The error bars represent the 95% confidence interval. The average starting pH was 6.3.