Atributos do solo em área de descartes de resíduos urbanos no Sul do Amazonas

Abstract

Soil is a dynamic ecosystem formed from the decomposition of rocks, and its evolution is linked to climatic, topographical and temporal factors. Population growth intensifies the generation of solid waste, and its inadequate disposal can cause significant changes in soil attributes. Irregular disposal of waste without adequate infrastructure can compromise soil quality and increase environmental impacts. Therefore, it is essential to understand the dynamics of soil chemical attributes in disposal areas, since such characteristics provide relevant information about its composition and quality. Thus, this study aimed to evaluate the impacts of inadequate disposal of urban solid waste on soil chemical attributes in Apuí, Western Amazon, Brazil. For this purpose, soil samples were collected at depths of up to 160 cm, distributed in 20 sampling points along four parallel transects, covering landfill, transition and pasture areas. The chemical attributes pH, soil organic matter (SOM), H+Al, Al³⁺, K⁺, Ca²⁺, Mg²⁺, cation exchange capacity (CEC) and base saturation (V) were analyzed, in addition to the microelements B, Cu, Fe, Mn and Zn and soil texture (sand, silt and clay fractions). The results showed significant differences in the chemical attributes of the soil between the investigated areas. The soil of the landfill area presented a higher pH, in addition to higher concentrations of K⁺, Ca²⁺ and Mg²⁺, while the transition and pasture areas showed higher levels of potential and exchangeable acidity. The statistical analysis revealed that the pH of the soil under the landfill was, on average, 31% and 34% higher than in the transition and pasture areas, respectively. This increase in pH reduced the mobility of heavy metals and favored the retention of nutrients in the soil profile. CEC and base saturation were higher in the landfill area, reflecting greater soil fertility in this region. Principal component analysis (PCA) demonstrated that pH has a positive influence on the availability of macro and micronutrients, such as P, K⁺, Ca²⁺, Mg²⁺, Cu and Zn. The accumulation of organic matter in the landfill area was attributed to the continuous deposition of waste, including plant and domestic material. However, the presence of nutrients in deep layers indicates risks of leaching, which may compromise adjacent water bodies. These findings indicate that inadequate disposal of urban solid waste substantially alters soil chemistry, making it more fertile, but with potential environmental risks. Therefore, it is recommended to implement management strategies, including segregation, treatment and continuous monitoring of waste, with a view to mitigating negative impacts and promoting environmental sustainability. The study contributes to the understanding of the effects of landfills on soil fertility and health, providing support for public policies and environmental recovery actions.