Behavior of arsenic and antimony in the surface freshwater reaches of a highly turbid estuary, the Gironde Estuary, France

This study reports on the behavior of two redox-sensitive elements, As and Sb, along the turbidity gradient in the freshwater reaches of the turbid Gironde Estuary. During a 17-month survey, surface water and suspended particulate matter (SPM) were sampled monthly at six sites representing both fluvial branches of the Gironde Estuary. Additionally, two longitudinal high resolution profiles were sampled along the fluvial estuary of the Garonne Branch during two contrasted seasons, i.e. with and without the presence of the maximum turbidity zone (MTZ). Seasonal variability and spatial distribution of dissolved (<0.2 μm; <0.02 μm) and particulate As, Sb and Fe were measured and combined with SPM data to understand metalloid behavior in the estuarine freshwater turbidity gradient.