Evaluation of heavy metals and arsenic speciation discharged by the industrial activity on the Tinto-Odiel estuary, SW Spain

► A huge discharge of heavy metals reaches the estuary of the Ría of Huelva (SW Spain). ► Two sources are responsible for pollution: the mining and an industrial estate. ► Metal contribution from the industrial sector is less than 1% of the total content. ► The treatment of mining wastes should be the priority goal to improve water quality.