Physicochemical properties and heavy metals distribution of waste fine particles and soil around urban and peri-urban dumpsites

Abstract

In developing countries like Ghana, the use of open dumpsites and landfills without proper waste management technique has resulted in environmental pollution with long-term adverse effects on soil, groundwater, human health and environmental sustainability. This study assessed the contaminants in fine particles of dumpsite waste and soil around urban and peri‑urban dumpsites at different depths of excavation and different age of deposited waste. Specifically, the study: (i) assessed physiochemical properties of fine particles of dumpsite waste and the surrounding soil, (ii) assessed heavy metals distribution from waste fine particles and surrounding soil at different depths and different ages of deposition, (iii) also determined soil quality indices (pollution index, geo-accumulation, and the potential ecological risk), and the hazards associated with the dumpsites on the residents living near the dumpsites. About 50 kg of waste was taken from surface, 0.5, 1.0 and 1.5 m depths. The samples were dried, segregated and sieved to obtain fine particles. Again, 1 kg soil was excavated form 0.5, 1.0 and 1.5 m depths at different age zones around each dumpsite. The fine particles and soil were analysed for physiochemical parameters using standard methods, and heavy metals using microwave plasma spectroscopy. The results showed that, the concentrations (electrical conductivity, potassium, cadmium, iron, copper and zinc) of waste fine particles and soil samples observed statistically significant different between them (p < 0.05). Waste particles recorded high cadmium and iron concentrations (41.7 mg/kg) and (4355 mg/kg) respectively at urban dumpsite. Similarly, there is statistically significant difference between calcium concentrations (p = 0.0221), potassium concentrations (p = 0.0227) and cadmium concentrations (p = 0.019) in the three age zones of urban dumpsite. The fine particles were heavily polluted with cadmium (PI > 6). High potential ecological risk of Hg (RI = 514.29), and (RI = 571.43) was observed at (SMZC1) and (NZA1) respectively; and high potential ecological risk of Cd (1000 ≤ RI ≤ 320), at (SMZA1-SMCA4. The study shows that both dumpsites have caused environmental hazards and this can cause surface and groundwater pollution and adverse effect on public health. But the study could not assess the impacts of dumpsite on leachate and water quality. The findings can be used as benchmark for developing appropriate technology for dumpsite mining, reclamation or decommission project; and exploit valorization potentials of the fine particles of the waste as composite and construction materials.