IMPACTS OF THE DISPOSAL OF URBAN SOLID WASTE ON SOIL QUALITY IN THE HUMID AND SEMIARID TROPICAL REGION
Soil degradation. Dumpsite. Anthropogenic soil.
Although waste disposal still occurs irregularly in many places around the world, information on the impacts of irregular disposal on soil quality after a long period of decommissioning and under different environmental conditions is scarce. In the present study, changes in the physical and chemical characteristics of the soil caused by the irregular disposal of solid waste in different dumpsites and climatic conditions were investigated. Soil quality was assessed in two locations with chronological succession in relation to waste disposal: (1) natural soil, with original soil characteristics; and (2) anthropogenic soil, present in deactivated dumpsites. Twenty-four areas were sampled, with twelve areas of anthropogenic soil and twelve areas of the respective natural soil. The soil samples were characterized physically and chemically and had the levels of heavy metals Copper, Nickel, Lead, Zinc, Chromium and Manganese. The results showed that the irregular disposal of residues significantly impacts the quality of the soil regardless of the current use of the dumpsites and the humid or semiarid tropical climate. The spontaneous growth of vegetation in the soils of the old dumpsites does not change the degradation condition of these soils. Among the sources of variation, the size of the dumpsite, the time the dumpsite remained active and the time that it was deactivated influenced the responses of the physical, chemical and heavy metal contents. Anthropogenic soils showed wide variability of the studied attributes, forming a group of more heterogeneous soils when compared to the respective natural soils. The attributes that best distinguished anthropogenic from natural soils were sand and clay content, Bd, TP, pH, soil organic carbon, available phosphorus and levels of heavy metals Cu, Pb, Ni and Zn. Our result highlights that the impacts of irregular waste disposal on soil quality are remarkable and persist for a long time if the areas are not recovered. These data are important for local authorities to establish more effective targeting policies for improving soil quality and controlling the spread of contaminants in areas impacted by the disposal of municipal waste.