Degradação do solo em áreas de disposição irregular de resíduos sólidos no semiárido tropical

Abstract

Disabling dumpsites without sanitary and environmental engineering measures increases potential degradation of the area and may cause other environmental liabilities. These dumpsites should be sent to recovery programs, based on soil diagnostics to identify the environmental degradation processes to assist degraded area effective recovery. Given the obligation to recover these areas established by Brazilian law, municipalities need studies like this to adapt the Brazilian legislation and solid waste management. The general aim of this study was to identify the environmental degradation processes installed in solid waste irregular disposal area in tropical semiarid, in order to guide the implementation of recovery programs in this area by the municipality. Therefore, we sought to: (1) evaluate the physical and chemical attributes of the cover soil from the deactivated dumpsite of the municipality of Olho D’água do Borges/RN, which results will be presented in CHAPTER I of this dissertation; and (2) assess whether the irregular disposal of solid waste in the dumpsite promotes soil contamination by heavy metals and expands the potential to spread to other parts of the watershed, which will be addressed in CHAPTER II of this dissertation. Soil samples were collected at depths of 0-20 cm and 20-40 cm on the deactivated dumpsite area, in ephemeral drainage area of Brejo dam and area under native forest used as quality reference in Olho D’água do Borges/RN. Therefore, the evaluated attributes in three areas were: bulk density (BD) and particles density (PD), total porosity (TP), particle size, pH, electrical conductivity (EC), organic matter (OM), available phosphorus (P), total nitrogen (N), exchangeable cations (Ca2+, Mg2+, Na+ e K+), exchangeable and potential acidity, and from these the sorption complex soil, available and total metals contents. Thus, the water and wind erosion, substrate cover disturbance, overload salts, available phosphorus, nitrogen, organic matter and heavy metal contamination are degradation processes identified as result of irregular disposal of solid waste in the soil. These processes contribute to increase the potential diffusion of dumpsite contaminants to the watershed, expanding the degraded area.