Compost-assisted phytoremediation of As-polluted soil

Abstract

The effect of organic matter on the As bioavailability in soils and thus on phytoremediation processes is still controversial. The objective of the present study was to evaluate the combined effect of compost and microorganisms from rhizosphere on the tolerance of barley and wheat plants to soil polluted with different concentrations of As for the application on phytoremediation strategies. A greenhouse experiment was performed using soil artificially contaminated with As at two doses. A compost obtained from sewage sludge composted with pruning waste was used (40 t/ha) as amendment. Plants were grown until the end of their growing cycle. Arsenic uptake and plant physiological and biochemical parameters as well as As availability and physicochemical properties in soil samples were analyzed. The impact of compost addition on the structure and diversity of the microbial communities of the rhizosphere was also evaluated using PCR-DGGE. Compost application induced a different behavior in both species. Compared to wheat and irrespective of As doses, in compost amended soils, barley plants showed an enhanced As translocation to the aerial part. The different bacterial communities structure found for each species, according to the PCR-DGGE cluster analysis, suggested that specific rhizobacteria of barley may have increased As bioavailability, and would therefore enhance its translocation to aerial parts. Both species could be used for phytoremediation proposes of As-polluted soils, and specifically, barley would be an interesting option for phytoextraction due to its higher biomass and high As translocation when compost is applied to As-polluted soil.