Assessment of Heavy-metal Pollution and Ecological Risk in Soils and Water of Oil-field Communities in Delta State, Nigeria, Using Integrated Pollution Indices

Mon, 12 Oct 2026 00:00:00 +0000

Petroleum exploration and production can alter the geochemical quality of surrounding soils and water through the introduction and redistribution of potentially toxic metals. This study assessed the degree of heavy-metal pollution and associated ecological risk in soils and water from the Apkai and Umusedege oil-field communities of Ndokwa East and Ndokwa West Local Government Areas, Delta State, Nigeria. Ten heavy metals, namely Ni, Cr, Cu, Co, Pb, Cd, Fe, Mn, As and Zn, were investigated in soil, while the detected subset was assessed similarly in water. Single-element pollution was evaluated using the contamination factor (CF), geo-accumulation index (I-geo), enrichment factor (EF) and potential ecological risk factor (Er); overall environmental quality was evaluated using the pollution load index (PLI), summed pollution index (PIsum), risk index (RI), average pollution index (PIave) and Nemerow pollution index. In soil, Cr, Co, Pb, Cd, As, Zn, Cu and Ni showed moderate contamination, while Fe and Mn showed considerable contamination; Ni, Cr, Cu, Pb and Zn were classified as low ecological risk, and Cd and As as moderate risk; most metals fell within the depletion-to-minimal-enrichment category, with As as the exception at moderate enrichment; and Cr, Fe, Mn and As showed light-to-moderate geo-accumulation, while the remaining metals were non-contaminated. In water, Cr, Cd and Ni showed moderate contamination, Fe and Mn showed considerable contamination, and Pb, Zn and Cu showed very high contamination; Pb showed considerable ecological risk, while Zn, Cu and Cd showed low-to-moderate risk. Mean PLI was 1.3 for soil and 1.7 for water, indicating pollution in both media under the adopted criterion; mean PIsum was 13.3 and 36.6, mean RI was 67.3 and 142.9, and mean PIave was 1.3 and 4.5 for soil and water, respectively, while the Nemerow index was almost identical between the media at 171.8 and 171.9. Collectively, the integrated indices point to measurable degradation of environmental quality in both compartments, with water showing consistently greater pollution pressure than soil, particularly through Pb, Zn and Cu. The results indicate that heavy-metal pollution in this oil-field environment warrants continued environmental monitoring and management, while also establishing an index-based baseline for the geochemical fractionation and human-health risk assessments that build on this dataset.

Signal Processing Approach for the Characterization and Modeling of Urban Noise: A Case Study of a City in Western Côte d'Ivoire

T. Guié Toa Bi, Bernard N’Zebaud, Sandjé Marcelin, Sié Ouattara, Alain Clement — Tue, 13 Oct 2026 00:00:00 +0000

Urban environmental noise is insufficiently characterized in many secondary cities in sub-Saharan Africa. This exploratory study characterizes short-duration urban sound recordings from five neighborhoods of Duékoué, Côte d’Ivoire (Kokoman, Antenne, Résidence, Belleville, and Guitrozon). Recordings were obtained with a Samsung Galaxy A13 smartphone at 09:00, 12:00, and 17:00 on Monday, Thursday, and Sunday and processed in MATLAB to derive A-weighted equivalent levels (LAeq), percentile levels (L10, L50, and L90), nuisance indices (LNP and TNI), loudness-related descriptors, spectral centroid, zero-crossing rate, and energy fractions in broad frequency bands. The processing chain emulated standard sound-level calculations; however, because the smartphone system was not traceably calibrated against a reference sound level meter and was not demonstrated to conform to IEC 61672, the reported sound-pressure levels are interpreted as approximate estimates rather than certified regulatory measurements. Across the tabulated sites, estimated LAeq ranged from 62.62 dB(A) in Antenne at 17:00 to 72.69 dB(A) in Résidence at 17:00. Temporal profiles differed among neighborhoods, while mid-frequency energy generally represented the largest share of the spectrum. The findings show that smartphone-based signal processing can provide useful comparative information on urban acoustic patterns when its metrological limitations are stated explicitly. Longer, traceably calibrated monitoring is required before formal compliance or population-exposure conclusions can be drawn.

Physical Science International Journal

Assessment of Heavy-metal Pollution and Ecological Risk in Soils and Water of Oil-field Communities in Delta State, Nigeria, Using Integrated Pollution Indices

Signal Processing Approach for the Characterization and Modeling of Urban Noise: A Case Study of a City in Western Côte d'Ivoire