Teores de metais pesados em cambissolo irrigado com água residuária doméstica e água de poço

Abstract

The supply of nutrients from domestic wastewater encourages the practice of reuse in agricultural production, but the presence of heavy metals, even at low concentrations, can cause environmental problems in the long term. This study analyzed the effects of the application of domestic wastewater and well water on heavy metal levels in a cambisoil cultivated with chili peppers. Thus, an experimental area of 744 m2 was established in Milagres rural community, Apodi-RN. This area is comprised of a sewage treatment station and drip irrigation system. The treatments were T1 - 100% of treated domestic wastewater (ART) and 0% of well water (AP), T2 - 75% of ART and 25% of AP, T3 - 50% of ART and 50% of AP, T4 - 25% of ART and 75% of AP and T5 - ART 0% of ART and 100% of AP. During the experimental period we chemically analyzed ART and AP, while soil samples were collected in the layers 0 to 0.20 m, 0.20 to 0.40 m and 0.40 to 0.60 m for determination of pH and the content of copper, zinc, iron and manganese. The results indicated that the levels of copper, zinc, iron and manganese on cambisoil were not influenced by the proportions of domestic treated wastewater and well water; however, the soil pH decreased as the proportions of domestic treated wastewater increased as compared to well water.