Uptake of 2,4-D and fipronil by green manure species: an ecotoxicological assessment of soil phytoremediation.

Pesticides such as 2,4-dichlorophenoxyacetic acid (2,4-D) and fipronil pose potential risks in agricultural soils, and phytoremediation is a promising alternative to mitigate their ecotoxicity. In this study, the potential of three green manure species, Canavalia ensiformis, Dolichos lablab, and Mucuna pruriens, was assessed in terms of their ability to reduce soil ecotoxicity by examining the uptake of 2,4-D and fipronil, both individually and in a mixture. The experiments were performed with 20 µg kg^-1 of each pesticide, lasting 30 days, and the contaminants were quantified in soil and plant biomass (shoots and roots). However, the plants did not significantly reduce pesticide concentrations, and only fipronil residues were detected in plant biomass. Elutriate samples (1 soil: 4 water) were prepared with soil samples after the exposure period, and their ecotoxicity was evaluated using tests with the cladocerans Ceriodaphnia silvestrii, Ceriodaphnia dubia, and Daphnia similis, the larvae of the insect Chironomus sancticaroli, and the germination of Eruca sativa. Bioindicators were sensitive when exposed to elutriate samples, particularly E. sativa to 2,4-D, while the other species to fipronil. While the phytoremediation potential was limited, the uptake of fipronil indicates the possibility for further improvement in soil remediation.