Sediment-seawater solute flux in a polluted New Zealand estuary

► We quantify sediment-seawater solute exchange in a polluted New Zealand estuary. ► This estuary is set to recover after diversion of a major wastewater outfall. ► We identify the biogeochemical signature (in terms of solute flux) of the wastewater effluent. ► We set the stage for studies of estuary recovery from anthropogenic eutrophication.