Bioacumulação de metais pesados em pequenos mamíferos em áreas de remanescentes de mata atlântica e monocultura de cana-de-açúcar na Paraíba, Brasil

Abstract

The Atlantic Forest is among the most important tropical ecosystems on a world scale, due to its high biological diversity and high degree of endemism, however this biome has been suffering intense devastation with the intense progress of agriculture. The increase in sugarcane crops around fragments of the Atlantic Forest can cause impacts due to the use of pesticides that lead to environmental contamination and the human being. Agriculture is a non-point source of pollution to the environment, mainly contamination by heavy metals, through the discharge of impurities from the use of phosphate fertilizers, pesticides and fungicides. Mammals are known as important bioindicators of environmental quality, as they provide an alert for adverse effects on ecosystems. Thus, the objectives of this work were to evaluate 1) if there is a difference in the bioaccumulation of metals in small mammals in of areas of Atlantic Forest remnants and sugarcane monoculture on the north coast of Paraíba, 2) if there is a difference in relation to other factors as to the body condition of the animals, to sex, between the three sampling areas, 3) if there are differences in relation to bioaccumulation in forest animals in relation to the distance from the edge of the forest to sugarcane. The study area corresponds to remnants of the Atlantic Forest and sugarcane monoculture in the state of Paraiba. Thirty-one small mammals were captured in sugarcane and 44 in forest remnants. The species studied were Didelphis albiventris, Marmosa murina, Marmosa demerarae, Monodelphis domestica, Akodon cursor, Mus musculus, Calomys callosus and Necromys lasiurus. Liver and kidney samples were removed. Lead (Pb), Nickel (Ni), Chrome (Cr) and Cadmium (Cd) were analyzed by Atomic Absorption Spectrometer. Analysis of Variance – ANOVA, Principal Componet Analysis – PCA and linear regressions were performed for the statistical analysis. We detected bioacumulation of heavy metals in small mammals found in sugarcane fields as well as in forest remnants. The results show that there was a higher bioaccumulation of metals in small sugarcane mammals, possibly due to the use of agrochemicals (pesticides and fertilizers) in the plantations. Rodents from sugar cane plantations showed a higher bioaccumulation of metals in relation to marsupials, due to the fact that they found almost predominantly in these areas. In relation to the bioaccumulation in the tissues, the liver presented the highest bioaccumulations, with lead being the metal with the largest amount in the tissue. In relation to the studied species, Didelphis albiventris, the white eared opossum, and Mus musculus, the house mouse, presented a greater bioaccumulation of heavy metals in comparison with the other species. The accumulation of heavy metals occurred independently of the distance from the sugarcane (max 1.5 km) and to the sex. The mechanism of bioacumulation of small mammals resident in the forest remnants should be investigated. There were two pathways for the accumulation of heavy metals in rodents and marsupials: accumulation together for cadmium and nickel metals, as well as for chromium and lead. For the species Didelphis albiventris and Mus musculus, the accumulation of heavy metals occurred by both routes, and for the other species, only by one route of contamination.