Journal of Global Ecology and Environment

Grain-Size Analysis of Sandy Sediments from the Substratum of Banco Bay, Abidjan, Lower Côte d’Ivoire

Diby Ferdinand Yao — 2026-09-18

Banco Bay, within the Ebrié Lagoon system of southern Côte d’Ivoire, contains sandy substratum deposits whose sedimentological characteristics remain insufficiently documented. While previous studies have largely focused on superficial lagoonal sediments and present-day sedimentary dynamics, limited information is available on the grain-size properties of the sandy deposits forming the bay’s substratum. Characterising these deposits is therefore important for improving understanding of their sedimentary features and depositional conditions. The studies conducted on the sandy facies of the substratum of Banco Bay aim to characterise the sandy levels of the bay using grain-size parameters and the interpretations derived from them. The methodologies used for this characterisation consisted of determining grain-size parameters, namely quantiles, quartiles, mean, mode, standard deviation, skewness, and kurtosis. The parameters were calculated using the classical method of moments. The main grain-size analyses made it possible to identify quasi-coarse sands throughout all the wells studied, indicating a moderate to turbulent palaeocurrent in the environment. Poorly sorted sands are more abundant than moderately sorted sands in all the boreholes studied. This sorting of the sands may be attributed to the currents that transported them. The currents were somewhat more regular for the moderately sorted sands, whereas the poorly sorted sands were transported by irregular currents. The curves are almost unimodal in all the wells. The results of these curves indicate one main sediment source supplying the entire bay. Skewness is generally positive, indicating that there are more grains with sizes greater than the mean. The different kurtosis values show a slight overall predominance of leptokurtic distributions across the tabulated samples. The grain-size parameters determined made it possible to characterise the sandy levels identified in the substratum of Banco Bay. These findings contribute to a better understanding of the coastal sedimentary basin, particularly the sands deposited on the bottom that form the substratum of the bay.

Integrated Hydrological and Hydraulic Approach for the Design of the Sorey Bridge under a Context of Climate Variability (Niamey Region, Niger)

Harouna Souley — 2026-09-18

The increasing hydroclimatic variability observed in the Sahel poses a major challenge to the design and safety of road infrastructure exposed to flooding. This study applies an integrated hydrological and hydraulic approach to the design of the Sorey Bridge in the Niamey Region of Niger. The methodology combines precipitation-frequency analysis, GIS-based morphometric characterisation of the watershed, estimation of the 10-year flood using the ORSTOM and CIEH methods, extrapolation of the 100-year flood using the GRADEX method, and hydraulic analysis based on the Manning–Strickler relationship. The watershed covers 1,359.75 km², with a perimeter of 285.32 km and a main channel length of 50.39 km. Rainfall analysis for 1991–2000 shows marked interannual variability, with mean annual precipitation ranging from 410.7 to 816.3 mm and a maximum daily rainfall of 129 mm. The 10-year discharges estimated by ORSTOM and CIEH are 196.22 and 225.86 m³/s, respectively, giving an adopted mean design discharge of 211.04 m³/s. The GRADEX method gives a 100-year discharge of 896.78 m³/s. Hydraulic analysis yields a flow depth of 3.40 m, a mean velocity of 2.90 m/s, and a backwater rise of 0.208 m. Total pier scour is 3.86 m. The proposed protection comprises 0.74-m-diameter riprap, with a 3.00-m width and 2.22-m layer thickness, together with a 2.00-m freeboard. These parameters support the hydraulic design of the Sorey Bridge under extreme flood conditions.

Moss-dwelling Testate Amoebae in Patratu Valley, Jharkhand, India: A Pilot Study

V. M. Sathish Kumar — 2026-09-23

Testate amoebae are shell-bearing protists that occur in a wide range of terrestrial and aquatic habitats and can provide useful information on microbial diversity and environmental conditions. This pilot study documents moss-dwelling testate amoebae from Patratu Valley, Jharkhand, India, where information on these organisms has been limited. Moss samples were collected from soil- and wall-associated microhabitats on 22 February 2026 and processed using the non-flooded Petri dish method. Permanent slide preparations were examined microscopically for species-level identification, and registered slides were deposited in the National Zoological Collections of the Gangetic Plains Regional Centre, Zoological Survey of India, Patna. The survey recorded 12 species belonging to five genera and five families. The recorded taxa included species of Cyclopyxis, Difflugia, Centropyxis, Euglypha, and Trinema. These observations provide a preliminary inventory of testate amoebae associated with moss microhabitats in the study area and extend baseline information on their regional occurrence. Because the investigation was based on a single pilot survey and did not quantify abundance or environmental variables, the recorded species richness should not be interpreted as a complete assessment of the local assemblage or as evidence of ecosystem condition. Broader spatial and seasonal sampling, together with standardised measurements of environmental variables, will be required to evaluate patterns of assemblage composition and their potential value in environmental monitoring.

Integrated Physicochemical, Hydrochemical, Trace-element and Microbiological Assessment of Groundwater across Contrasting Geological Settings

Madu Onyeka Emmanuel — 2026-10-01

Groundwater is an important source of domestic water supply, but its quality may vary according to geological setting, mineral–water interactions and microbiological contamination. This study evaluated the physicochemical, hydrochemical, trace-element and microbiological characteristics of groundwater across Basement Complex, Younger Granite, shale/sedimentary and weathered-regolith geological settings. Groundwater samples were analysed for pH, electrical conductivity (EC), total dissolved solids (TDS), turbidity, total hardness, alkalinity, major ions, selected trace and potentially toxic elements, heterotrophic bacteria, total coliforms, faecal coliforms, Escherichia coli and enterococci. Hydrochemical facies were determined from the major-ion composition, while differences among geological settings were evaluated using one-way analysis of variance, and relationships between chemical and microbiological variables were assessed using Pearson's correlation analysis. The groundwater was slightly acidic to near neutral, with pH values ranging from 6.21 ± 0.14 to 6.78 ± 0.16. Basement Complex groundwater exhibited the highest EC (486 ± 42 µS/cm), TDS (312 ± 28 mg/L), total hardness (146 ± 12 mg/L), calcium (48.6 ± 4.2 mg/L), magnesium (18.4 ± 2.1 mg/L) and bicarbonate (118 ± 10 mg/L). The shale/sedimentary setting recorded the highest concentrations of several trace elements, including Pb (0.014 ± 0.003 mg/L), Cd (0.0026 ± 0.0005 mg/L), Cr (0.018 ± 0.004 mg/L) and Ni (0.021 ± 0.004 mg/L). Ca–Mg–HCO₃ was the predominant hydrochemical facies. Microbiological contamination varied spatially, with weathered-regolith groundwater recording the highest total coliforms (31 ± 7 CFU/100 mL), faecal coliforms (15 ± 4 CFU/100 mL), E. coli (11 ± 3 CFU/100 mL) and enterococci (9 ± 3 CFU/100 mL). Significant differences occurred among geological settings for the assessed physicochemical, chemical and microbiological parameters (p < 0.05). Turbidity and nitrate showed positive associations with the principal microbiological indicators. The findings demonstrate that geological setting influences groundwater mineralisation and trace-element distribution, while microbiological quality may respond to additional factors associated with groundwater vulnerability and contamination pathways. Integrated chemical and microbiological monitoring is therefore important for evaluating groundwater quality and its suitability for domestic use.

Used Lead-Acid Batteries from Nigeria's Off-Grid Solar Sector: Environmental Health Risks, Regulatory Gaps and Circular-Economy Responses

George-Oloja Nkechinyere — 2026-10-01

Background: Nigeria’s rapid expansion of off-grid solar systems is increasing the use and eventual disposal of lead-acid batteries, yet the contribution of solar-derived batteries to the country’s wider used lead-acid battery waste stream remains poorly quantified.

Aim: This narrative review examined the management of used lead-acid batteries from Nigeria’s off-grid solar sector, associated environmental and public-health risks, regulatory gaps, and circular-economy responses.

Methodology: MEDLINE, Scopus, the Cochrane Library and Google Scholar were searched from inception to August 2026, together with relevant institutional and Nigerian government sources. Evidence was categorised as Nigerian solar-battery evidence, Nigerian lead-acid battery evidence of unspecified origin, evidence from other African settings, or general lead toxicology.

Results: No identified Nigerian study directly attributed measured lead exposure or contamination to batteries originating from off-grid solar systems. However, evidence from the wider Nigerian battery-recycling stream shows substantial occupational and environmental hazards. Informal recycling workers had a mean blood lead level of 40.17 µg/dL compared with 3.61 µg/dL among controls, while soil lead concentrations reached 29,000 ppm outside recycling facilities. Nigeria has battery regulations and an extended producer-responsibility framework, but important implementation gaps remain in enforcement, traceability, institutional coordination and informal-sector oversight.

Conclusion: The downstream environmental and health burden attributable specifically to off-grid solar batteries remains unquantified. Source-level traceability at collection is therefore necessary to distinguish solar batteries within the wider waste stream and support sector-specific accountability.