Mobility of contaminants in phosphogypsum of the fertilizer industry of Huelva (SW Spain)

The dynamic of trace elements from phosphate rock ore to the environment in a phosphoric acid plant located in SW Spain and the impact of phosphogypsum wastes were investigated through total digestion and BCR-sequential extraction. Based on those concentrations that are likely to be most readily mobile in the environment, phosphogypsum acts as a higher emission source of contaminants than the original rock. About 100 million tonnes of phosphogypsum are stack-piled in a dump of 1200 ha over salt- marshes of an estuary formed by the confluence of the Tinto and Odiel rivers. Phosphogypsum capacity as a source ofmobile contaminants in three environmentalscenarios (water leaching, exposure to oxidising and reducing conditions) was quantified by combining sequential extraction and waste mass. The amounts of mobile contaminants that could be released for every tonne of phosphogypsum are approximately 7-102 gSr, 1.1-102 gTe, 55 gY, 30 gCe, 12gCr, 11 gTi, 5 gZn, 4 g each of Cu and Pb, 3 g each of V and Cd, 2 g each of As and Ni, and 1 gU. Multiplying these amounts by 100 Mt, it is possible to calculate risk assessments of phosphogypsum for estuarine zone