Arsenic speciation in soils and Erica andevalensis Cabezudo & Rivera and Erica australis L. from São Domingos Mine area, Portugal

Arsenic is very abundant in the Iberian Pyrite Belt (IPB) and it might have hazardous consequences for plants. The chemical speciation is an important factor to take into account in toxicity evaluations. Arsenate is analogous to phosphate and it can seriously interfere with cellular processes. In the present study we have analysed by high performance liquid chromatography-inductively coupled plasma-mass spectrometry (HPLC-ICP-MS) the arsenic speciation in soils from São Domingos mine area (IPB) and arsenate resulted to be the major species. The arsenic content and speciation analysis have been carried out also in two metal tolerant species from that area: Erica andevalensis, endemic heather from the mining areas of the Southwest Iberian Peninsula, and Erica australis, a widely distributed species. The total content of arsenic ranged in soils from 194 to 7924mgkg−1 (dry mass), and from 1 to 24.4mgkg−1 in E. andevalensis and from 2.7 to 11.6mgkg−1 in E. australis. The organic forms of arsenic were almost absent, with only dimethylarsinate (DMA) found in some samples of E. andevalensis. These plant species must possess different tolerance mechanisms, as E. australis accumulates mainly arsenite, while in E. andevalensis arsenate is the most abundant species in some cases. ► Erica andevalensis and E. australis are heathers able to survive in acid mining soils. ► Soils contain high arsenic concentrations that are adsorbed and accumulated in plants. ► Arsenate is the most abundant species in the soils and plants. ► Arsenic-binding mechanisms in plant avoid total extraction with methods commonly used. ► Both Erica species are candidates for phytostabilisation in mining environments.