Biochar-pesticides interactions: An overview and applications of wood feedstock for atrazine contamination

The herbicide atrazine has been extensively applied to several crops, and its accumulation in soils and waters can cause environmental impacts and risks to human health. Remediation of contaminated areas has become a global concern, and biochar stands out as an emerging technology for the sorption of pesticides residues. This systematic review aims to synthesize the state-of-knowledge for feedstocks used in the biochar production and its application with different pesticides, providing an overview of the outcomes from the most studied feedstock and pesticide. Retrieved documents regarding the combined use of the two factors (i.e., wood and atrazine) were selected for analysis. In general, the sorption results of the publications had good fits to the Freundlich model; though, Langmuir and linear isotherms were also applied to describe the atrazine sorption. Initial concentrations of atrazine ranged from 0.001 to 200 mg L-1 in equilibrium tests, aiming to assess the maximum sorption capacity of the biochar; However, a great part of these concentrations exceed the values usually detected in freshwater (at mu g L-1 levels), which significantly limits the evaluation of the toxicological potential after treatment with biochar. Another knowledge gap refers to the effects of atrazine on terrestrial organisms, which are even less studied than those on aquatic species. Ecotoxicity bioassays should be combined with sorption experiments to study different parameters (e.g., equilibrium, kinetics, and column). Future research should address the complexity of ecosystems, desorption experiments, field application, biochar aging, atrazine degradation, and microbiology.