Acumulação de arsênio em Coffea arabica sob diferentes fontes via solo

Abstract

Arsenic (As) is a toxic metalloid widely distributed in Brazilian agricultural soils, whose presence, even at low concentrations, represents a significant risk to human health due to its high mobility and potential for accumulation in plants. This risk may be intensified by anthropogenic activities, such as the use of contaminated fertilizers, including ulexite, which may contain high concentrations of this element. In this context, the present study aimed to evaluate the capacity of coffee plants (Coffea arabica) to absorb As and accumulate the element in their vegetative and reproductive tissues, allowing inferences regarding potential risks to the food chain. The experiment was conducted in a nine-year-old coffee plantation established in a Typic Hapludox (Dystrophic Red Latosol), at the Experimental Farm of the Federal University of Uberlândia, Minas Gerais, Brazil. The treatments were arranged in a 3 × 2 + 2 factorial scheme, consisting of three As sources (arsenate, arsenic trioxide, and realgar), two application forms (powder and suspension), and two additional treatments (control and realgar in aqueous suspension), distributed in a randomized block design with three replications. The As dose corresponded to 4900 mg.plant⁻¹, simulating the accumulation resulting from successive applications of contaminated ulexite. Applications were performed around the plants within an approximately 25-cm radius at the end of the vegetative dormancy period. Before treatment application, soil, roots, and young and old leaves were analyzed to determine As concentrations. After application, young and old leaves, as well as fruits, were evaluated again. The results indicated that the soil in the experimental area had an initial As concentration of 11.3 mg.kg⁻¹, higher than that observed in a nearby native vegetation area (4.0 mg.kg⁻¹), suggesting possible enrichment associated with the agricultural history of the area. In the roots, 2.9 mg.kg⁻¹ of As was detected, whereas leaf concentrations were below the detection limit before treatment application. The application of different As sources and forms significantly influenced As accumulation in coffee leaves. The solution form resulted in higher concentrations in old leaves for arsenate (2.30 mg.kg⁻¹) and arsenic trioxide (1.87 mg.kg⁻¹), and in young leaves for arsenic trioxide (0.97 mg.kg⁻¹) and arsenate (0.87 mg.kg⁻¹), whereas realgar showed low availability regardless of the application form. The greater accumulation in old leaves and the absence of As in fruits indicate limited translocation and accumulation of the element in young and reproductive tissues. These results suggest that, although coffee plants absorb and translocate As to vegetative tissues, mechanisms restrict its transfer to fruits, even under high soil contamination, thereby reducing the direct risk associated with human consumption. In conclusion, coffee plants have the potential to absorb and accumulate As, particularly in roots and leaves, but do not exhibit relevant accumulation in coffee beans.