The migrated behavior and bioavailability of arsenic in mangrove sediments affected by pH and organic acids

Batch experiments were conducted to study the migration behavior of arsenic (As) and iron (bivalent, trivalent, and total Fe) of the presence of the low molecular weight organic acids (LMWOAs) citric acid, malic acid, and oxalic acid in As-enriched mangrove sediments. The results for supernatant As/Fe species were significant according to each LMWOA treatment. Significant non-linear correlations were found among As level, pH, and acid dose based on our predictive model. The capacity of LMWOAs to mobilize As/Fe species followed the order of citric acid > malic acid/oxalic acid. The supernatant As correlated positively with the LMWOAs dose and negatively correlated with the pH. As migration was affected by acid strength, the number of carboxyl groups, the pH and levels of Fe compounds in the sediments. The results indicate that LMWOAs can potentially attenuate As contamination from mangrove sediment, allowing for a better understanding of As/Fe behavior in the rhizosphere. [Display omitted] •LMWOAs acted as an activator to facilitate As/Fe transfer from the solid phase to the liquid phase.•Citric acid is a better desorbent and extractant than malic acid and oxalic acid.•Dosage, type, and pH of LMWOAs jointly influence desorption of As and Fe.