Evaluación de la capacidad fitorremediadora de una especie nativa sudamericana ("Discaria americana") en un suelo enmendado con lodos de depuradora

Abstract

Biosolids are an organic waste of biological origin, produced in domestic wastewater treatment plants. At present, their correct management is one of the biggest challenges in the framework of the sustainable development of big cities. Its agricultural use is one of their most accepted fates from an ecological and economic point of view. However, they may have varying concentrations of certain potentially-toxic trace elements (TE), which react with the soil components, being distributed within fractions with different bioavailability. The general objective of this work was to determine the phytoremediation capacity of Cu and Zn of a South American native species, the American Discaria (Discaria americana), in a typic Hapludol with sandy texture amended with biosolids (SB) or biosolids enriched with their own ashes (SZ). The effect of increasing doses of B or Z on germination parameters of D. americana compared with ryegrass (Lolium perenne L.) was analysed, without observing phytotoxic effects in either of the two species. After 180 days, a redistribution of Cu and Zn between the different edaphic fractions in a sandy soil amended with biosolids or biosolid enriched with its own ashes as a result of the radical activity of D. americana and ryegrass was observed. The radical activity of both species favoured the passage of both elements to lower bioavailability forms, closely related to soil pH. Between days 120-130, D. americana presented symptoms of phytotoxicity in SB, and a high concentration of Cu in both aerial and radical biomass. These results may be related to the high dose of amendment used. These symptoms did not manifest in SZ, indicating that biosolids´ inorganic matrix was capable of retaining ET in less bioavailable forms. D. Americana behaved as an exclusion species for Zn.