Arsenic distribution in shoots of the halophyte plant species Atriplex atacamensis growing in an extreme arid mining area from Northern Chile

The oasis of Quillagua is an As contaminated area located in the North part of Chile along the Rio Loa. This study was undertaken in order to quantify As accumulation in water, soil and plants of the xerohalophyte species Atriplex atacamensis growing along the river. The water samples from the Rio Loa contained up to 2.5 mg L-1 arsenic and were highly saline (EC 14.1 mS cm-1). High concentration of B was associated to near-neutral pH values. The soil was typically corase – textured with a high proportion of sand. A mean As concentration of 220 mg Kg-1 was recorded in the soil and an important proportion was associated to iron oxide. Mature plants of Atriplex atacamensis were able to grow on this contaminated area and accumulated moderate amounts of As in the shoots. Arsenic concentration was higher in the leaves tan in the stems, but consistent amounts of As accumulated in the mature seeds and in surrounding bracts. The vegetative plant organs also accumulated high amounts of Na, confirming the halophytic nature of the plant species. Mature shoots are characterized by low amounts of P, probably as a consequence of As competition for P transporters, and by high amounts of S, probably resulting from phytochelatins and glutathione over synthesis.