Assessment of Soil Physicochemical Properties and Enzymatic Activities in Municipal Dumpsites of Uyo, Akwa Ibom State, Nigeria

Abstract

Soil enzyme activities are sensitive indicators of soil biological functioning and nutrient cycling, particularly in environments impacted by municipal solid waste (MSW) disposal. This study evaluated selected physicochemical properties and enzyme activities of soils from three municipal dumpsites (Calabar–Itu Road, Uyo Village Road, and Eka Street) in Uyo metropolis, southern Nigeria, to assess their soil quality status. Surface soil samples (0–20 cm) were collected in triplicate and analyzed for particle size distribution, pH, electrical conductivity (EC), organic carbon (OC), total nitrogen (TN), available phosphorus (AvP), exchangeable bases, and effective cation exchange capacity (ECEC). Enzyme activities, including actual and potential dehydrogenase, urease, acid phosphatase, and alkaline phosphatase, were determined using standard colourimetric methods. Data were subjected to analysis of variance at p ≤ 0.05. Results indicated that dumpsite soils were predominantly sandy with acidic to slightly acidic pH. Organic carbon and nutrient levels were elevated relative to typical background soils of the region, reflecting continuous organic waste deposition. Enzyme activities varied significantly among dumpsites (p ≤ 0.05), with higher dehydrogenase and urease activities observed in sites with greater organic carbon content. Acid phosphatase activity was generally higher than alkaline phosphatase, consistent with the acidic soil conditions. The findings demonstrate that municipal waste inputs substantially modify soil biochemical functioning, enhancing microbial and enzymatic activities through organic substrate enrichment. However, the altered biochemical dynamics may have long-term implications for nutrient balance and environmental quality. Soil enzyme activities proved to be reliable indicators of ecological changes in dumpsite-affected soils and can serve as valuable tools for soil quality assessment and sustainable waste management planning.