Avaliação do potencial fitorremediador de Mentha Crispa L. cultivado em solo contaminado com Cd e Zn: efeitos da aplicação próxima aos limites perimitidos pela resolução Conama 420/2009

Abstract

Accelerated urban development, natural areas are constantly threatened by anthropogenic activities that result in the accumulation of toxic metals, such as cadmium (Cd) and zinc (Zn), in the soil. These contaminants cause adverse effects on plants and can impact the food chain. This study aimed to evaluate the efficacy of phytoremediation using the species Mentha crispa L. in a Red Latosol simultaneously contaminated with Cd and Zn, at concentrations close to the limits established by CONAMA Resolution No. 420/2009 for agricultural areas. To this end, plants were cultivated for 110 days in soils with increasing metal concentrations (treatments C1 to C9) and a control (without metal addition), under natural light and temperature conditions. Morphological and physiological parameters were analyzed, such as root mass and length, shoot height, number of leaves, leaf area, and chlorophyll concentration. At the end of the period, the plants were separated into roots, stems, and leaves to quantify the Cd and Zn concentrations in each compartment. From these data, the bioaccumulation (BF) and translocation (TF) factors were calculated, as well as the metal extraction rate. The results revealed that Mentha crispa L. exhibited high efficiency in Cd phytoextraction, with high BF and TF values, even at low soil concentrations. It was observed that Zn was predominantly translocated to the plant's aerial parts, with TF > 1 in several treatments, while Cd tended to concentrate preferentially in the roots, indicating distinct physiological behaviors and selective absorption mechanisms. The interaction between the elements affected absorption and mobility, with Cd being absorbed and translocated more efficiently, possibly mediated by mechanisms associated with Zn transport. It is concluded that Mentha crispa L. is a promising species for application in phytoremediation strategies, especially for the removal of Cd in areas with light to moderate contamination. Additionally, its economic potential as an aromatic plant for essential oil production makes it a sustainable, low-cost, and easy-to-implement alternative for the mitigation of environmental impacts.