Phytoremediation of soil with tebuthiuron associated with microbial inoculants

Abstract

The herbicide tebuthiuron is used in sugarcane crops and it also can cause numerous losses in water and soil ecosystems. This is due to its physicochemical aspects, such as high persistence in soil and high toxic potential. Thus, bioremediation implementation becomes a very effective and viable solution for degrading polluting compounds in environment. As a result, the present study aims to evaluate the phytoremediation potential of velvet bean (Mucuna pruriens L. DC.) and jack bean (Canavalia ensiformis) with microorganisms addition in soil associated with tebuthiuron. Phytoremediation efficiency will be evaluated in a completely randomized design, with five replications in a triple factorial scheme. An experiment will be performed in a greenhouse using pots with soil with the association of tebuthiuron and microbial inoculants. Potentially phytoremediation species tested will be M. pruriens and C. ensiformis. Moreover, Crotalaria juncea will be used as sentinel species. Throughout the experiment, biometric parameters will be evaluated: stem diameter, plant height and number of leaves. Assessments of root length and fresh and dry biomass will be determined at the end of plant development. Moreover, the herbicide residual concentration in soil samples will be analyzed, as well as possible intermediate compounds generated by its degradation. The ecotoxicological potential of soil samples will be monitored based on bioassays with the following test organisms: lettuce seeds (Lactuca sativa), Enchytraeus crypticus and earthworms (Eisenia foetida). Soil samples ecotoxicity will be characterized in initial (t0) and final (t70) times. Ecotoxicity tests with the two bioindicator annelid species are associated with a BEPE proposal submission to the University of Coimbra, Portugal. Finally, results will be evaluated statistically by variance distribution and homogeneity using Bartlett's normality and homoscedasticity tests, followed by analysis of variance. For characteristics that present significance in this analysis, Tukey test (pd0.05) will be performed on means comparison. Furthermore, other methods of data presentation and mathematical modeling will be used (correlation test, response surface model adjustment, diffuse contour plotting and principal component analysis). The statistical analysis will be performed through routines to be developed in the free software R. (AU)