The NF-POGO Scholars Lailah Gifty Akita and Lazare Kouame Akpetou published the following article in the Water, Air & Soil Pollution Springer Journal

Increasing human activities in coastal cities and countries have contributed to pollution of coastal water bodies. The sub-Sahara Africa region is faced with several pollutions. Mercury pollution is a major threat to aquatic ecosystems, biota, and human health. This study evaluated the spatial distribution of total mercury (THg) and methyl mercury (meHg) and its associated ecological risks across selected sampling stations in five transitional waters across the Western Atlantic Ocean: Ebrié Lagoon (E.L., Côte d’Ivoire), Volta Estuary (V.E., Ghana), Lake Togo (L.T., Togo), Lake Nokoué (L.N., Benin), and Lagos Lagoon (L.L., Nigeria). Forty-eight sediment samples were selected based on their respective ecological relevance and associated anthropogenic pressure during the dry season (November 2022, February, and March 2023) using Eckman and Van Veen grabs. The sediment was air-dried for preservation. Before analysis in Ghana, the sediments were oven-dried at 60°C and homogenised. Approximately 0.2 g of fine sediment (< 63 μm) was obtained from each station. THg and meHg were analyzed using a Direct Mercury Analyser (DMA-80). Univariate and multivariate statistical analysis, single and integrated pollution index (e.g., Contamination Factor, CF; Ecological Risk Factor, ERF; Modified Hazard Quotient, mHQ; Synergistic Toxic Risk Index, STRI; and Sediment Quality Guidelines, SQGs) were employed to assess Hg pollution and the extent of contamination in aquatic ecosystems. THg concentrations in five transitional waters ranged as follows: E.L, 0.030 to 1.885 mg/kg; V. E., 0.010 to 0.140 mg/kg; L.T, 0.0022 to 0.0092 mg/kg; L.N, 0.0052 to 0.223 mg/kg; and L.L, 0.003 to 0.715 mg/kg. The MeHg concentrations ranged from below-detectable level (bdl) to 0.017 µg/kg and bdl to 0.057 µg/kg at E.L and V.E, respectively. Other stations showed bdl concentrations, indicating site-specific MeHg formation controlled by localized sedimentary and environmental conditions. The STRI showed high risk at ≈ 21.42% and ≈ 10% of the stations at E.L, and L.L, respectively. Approximately 8% of the stations at V.E and L.N showed low to considerable risk. The results suggest THg enrichment at these stations, linked to localised anthropogenic input. Areas with enriched THg concentrations on the western Atlantic coast require continuous monitoring of local, regional, and transboundary pollution.

Keywords

• Total mercury (THg)
• Methylmercury (MeHg)
• Single and integrated pollution index
• Transitional coastal waters
• Gulf of Guinea
• West Africa

Link for the publication here.