Abstract
The Amazon soils demand high rates of fertilizer application to express high agricultural potential, making it necessary to carry out frequent monitoring of ecological functions and biogeochemical processes in this important biome. The concentrations of As, Ba, Cd, Co, Cr, Cu, Hg, Ni, Pb and Zn and contamination indexes were studied in Oxisol and Ultisols cultivated with citrus (Citrus sinensis (L.) Osbeck), oil palm (Elaeis guineensis Jacq.) and black pepper (Piper nigrum L.), at 26, 10 and 5 years of implantation, respectively. The potential risk of contamination was estimated by the enrichment (EF) and bioaccumulation (BAF) factors. Moderate enrichment of Ba, Pb and Zn (2 < EF < 5) and significant enrichment of As and Cu (5 < EF < 20) were observed. In addition, the following orders of bioaccumulation were found: oil palm—Cu > Zn > Hg > Ni > Ba > Co > As > Cr > Cd ≈ Pb; black pepper—Zn > Hg > Cu > Ba > Ni > Co > Pb >> As > Cr > Cd; and citrus—Hg > Ni > Ba > Zn > Co > Cu > As > Pb >> Cr > Cd. However, all elements are in concentrations below the prevention and investigation values established by Brazilian legislation, that is, the management practices in the crops studied are not contributing with damage to soil and human health risks.
Highlights
The Brazilian Amazon is a new agricultural frontier and a major food producing area, exporting soy and beef to global markets [1]
According to the United States Soil Taxonomy [41], the soil of oil palm cultivation is classified as Typic Hapludox, while the soils of black pepper and citrus cultivation are classified as Typic Hapludult (Table 1)
The soils of areas cultivated with oil palm and citrus showed values of pH H2O equal to 4.6 and 4.7, respectively (Table 1), and the soil cultivated with black pepper presented a pH H2O of 5.2
Summary
The Brazilian Amazon is a new agricultural frontier and a major food producing area, exporting soy and beef to global markets [1]. In this biome, there is a pressing challenge to reconcile food production and conservation of natural ecosystems [2]. The disposal of waste and the application of pesticides and fertilizers can increase the concentration of potentially toxic elements (PTEs), such as Pb, Cd, Cu, Mn, Zn and Hg, in soils and groundwater, which may cause toxicity risks to the ecosystem and human health [11,12,13,14,15,16,17]. These elements occur naturally, anthropogenic sources contribute significantly to increased rates of PTE redistribution among the compartments of the environment [18,19]
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