Distribuição espacial de metais pesados e riscos ecológicos em solo de lixão

Abstract

The improper disposal of municipal solid waste (MSW) in open dumps poses an environmental threat, particularly due to alterations in soil properties and the potential for the migration of substances to adjacent areas. This study evaluated soil chemical quality at a dump site in the municipality of Apuí, Amazonas, by developing and applying a Soil Quality Index (SQI). Samples were collected from the 0–60 cm layer at 16 georeferenced points: 12 within the dump site and four in a control area (pasture). Chemical attributes (pH, soil organic matter - SOM, potential acidity - H+Al, aluminum - Al³⁺, potassium - K⁺, calcium - Ca²⁺, magnesium - Mg²⁺, cation exchange capacity - CEC, and base saturation - V), microelements (boron - B, copper - Cu, iron - Fe, manganese - Mn, and zinc - Zn), and soil texture were analyzed. Data were subjected to Principal Component Analysis (PCA), selection of a Minimum Data Set (MDS), and SQI construction using both additive and Nemoro methods. The dump site exhibited significant changes in ten chemical attributes, showing increases in pH, P, K⁺, Ca²⁺, Mg²⁺, V, Cu, and Zn, and reductions in Al³⁺ and H+Al compared to the control area. PCA explained 83.94% of the total variance and allowed for the selection of two indicators for the MDS: pH and K⁺. K⁺ showed the greatest explanatory power regarding the variation of the additive SQI (SQIa) at the dump site (R² = 0.4488; p < 0.05). The SQIa was 0.64 ± 0.13 in the control area and 0.50 ± 0.03 at the dump site, representing a 21.9% reduction in soil quality, although both areas remained within the moderate quality class. Therefore, the improper disposal of municipal solid waste caused significant changes in the soil's chemical properties and reduced its overall quality, potentially fostering degradation processes and the mobilization of potentially contaminating substances.