Revista de biorremediación y biodegradación

Abstracto

Distribution and Mineralization of ¹⁴C-Hexazinone in Soil Microcosm with the Riparian Forest Specie Cecropia Hololeuca

Marinho DA, Bicalho ST, Ferreira EM and Langenbach T

Although Brazil is one of the world’s largest consumers of the herbicide hexazinone there are few studies, in the country, on the fate of this compound in the environment. This work studied the distribution and mineralization of hexazinone in a microcosm, with and without plants. The herbicide ¹⁴C-hexazinone was applied to microcosms with soil and C. hololeuca seedlings and mineralization and volatilization was monitored over a two month period. After this incubation period, radioactivity was measured in different soil layers, the rhizosphere, as well as in parts of the plant: fine and thick roots, stems, and leaves. The results showed that evaporation promoted an upward movement of hexazinone to higher soil layers which was enhanced in the presence of plants, due to evapotranspiration. The mass balance showed an uptake of 12.2 % in plants, and the leaves had the highest bioaccumulation value (9.1%). Mineralization in the soil microcosm was low, about 0.6 % but with the presence of plants it increased to 1.15 % without increasing the CFU of hexazinone and lignin biodegrader fungi. Bioremediation of hexazinone by biodegradation and accumulation in plant biomass reduced its concentration in the soil slightly, showing that this molecule can have hazardous consequences for the environment.