Ecotoxicological characterization of sugarcane vinasses when applied to tropical soils.

The impact of sugarcane vinasse on soil invertebrates was assessed through ecotoxicological assays. Increasing concentrations of two vinasses from different distillery plants (VA and VB), and a vinasse from a laboratory production (VC), were amended on two natural tropical Oxisols (LV and LVA) and a tropical artificial soil (TAS) to characterize the effects of the vinasses on earthworms (Eisenia andrei), enchytraeids (Enchytraeus crypticus), mites (Hypoaspis aculeifer) and collembolans (Folsomia candida). The highest concentrations of VA and VB were avoided by earthworms in all soils and by collembolans especially in the natural soils. The presence of VC in all of the tested soils did not cause avoidance behavior in these species. The reproduction of earthworms, enchytraeids and collembolans was decreased in the highest concentrations of VA and VB in the natural soils. In TAS, VB reduced the reproduction of all test species, whereas VA was toxic exclusively to E. andrei and E. crypticus. The vinasse VC only reduced the number of earthworms in TAS and enchytraeids in LVA. The reproduction of mites was reduced by VB in TAS. Vinasses from distillery plants were more toxic than the vinasse produced in laboratory. The vinasse toxicities were influenced by soil type, although this result was most likely because of the way the organisms are exposed to the contaminants in the soils. Toxicity was attributed to the vinasses' high salt content and especially the high potassium concentrations. Data obtained in this study highlights the potential risk of vinasse disposal on tropical soils to soil biota. The toxic values estimated are even more relevant when considering the usual continuous use of vinasses in crop productions.