Sedimentary environmental quality of a biosphere reserve estuary in southwestern Iberian Peninsula

Abstract

The Huelva estuary is formed by the common mouths of the Odiel and Tinto Rivers, and inside this ecosystem is the biosphere reserve of the Odiel saltmarshes. This ecosystem has been historically affected by acid mine drainage (AMD) and by releases of pollutants from five phosphoric acid industrial plants and phosphogypsum (PG) waste stacks located in the area. This study carried out a comprehensive assessment of the environmental impact of the biosphere reserve of the Odiel saltmarshes. To this end, it was necessary to find a suitable sedimentary background (Piedras River in our case). To quantify this impact, several pollution indexes were used. According to the values reached by the indexes, this impact was classified as "serious" pollution for most trace elements, excepting the deepest layers, and "low-moderate" pollution for the ²³⁸U-series radionuclides, while no pollution for the ²³²Th-series and ⁴⁰K radionuclides was found as expected.

Keywords: Acid mine drainage; Fertilizer industry; Natural radionuclides; Phosphogypsum piles; Pollution indexes; Trace elements.