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The Water Quality Index (WQI) was used to evaluate the ecological health and status of Owalla Reservoir and the implications on fish species distribution and biological diversity of the reservoir. Water quality and fish species were collected from three sampling zones (A, B, and C) from September 2019 to August 2020 and biological diversity indices such as dominance, Shannon-Weiner, Evenness, Brillouin, Menhinick, Margalef, Equitability, and Fishers index were calculated. The mean values measured for the temperature (25.9 ± 0.48 oC), dissolved oxygen (4.14 ± 0.10 mg/L), pH (7.0 ± 0.01), and nitrate (0.68 ± 0.25 mg/L) of Owalla Reservoir were within the recommended range; while ammonia (0.13 ± 0.20 mg/L), nitrite (0.14 ± 0.21 mg/L) were high and above the recommended limits. The WQI was highest in zone A (155.97) with an overall index value of 152.73 for the reservoir. Zone A recorded the highest relative fish abundance (49.95%) and was more diversified than other sampling zones. In terms of fish biodiversity indices, zone A had the highest richness (9), number of individuals (136), Shannon (1.84), and Brillouin (1.62) index values. Zones B and C were highest in terms of Dominance (1.0), and Evenness (1.0). Zones A and C were highest in terms of Simpson (0.83); zone B was highest in terms of Menhinick (1.58), and Fisher_alpha index (3.98) while zone C was highest in terms of Margalef (2.0), and Equitability (0.99) indices. The elevated levels of WQI, ammonia, and nitrite pose a danger to fish species and watershed systems. It is important to maintain the quality of water within Owalla Reservoir by ensuring best human practices and averting inappropriate human wastes as well as sewage disposal and agricultural activities. These should be checked for the sustainability of fish species.

The study investigated the source, geochemical spreading and risks assessment of trace metals in particulate matter 2.5 (PM2.5) within a gas flaring area in Bayelsa State, Nigeria. PM2.5 was measured using Geintek Particulate matter sampler APM131 monitor. Seven locations within 3000 m of the gas flaring area were sampled, with a control location established at about 7000 m from flare stark. The trace metals trapped in the PM2.5 were analyzed using flame atomic absorption spectrometry. The mean level of trace metals ranged from 2.75 – 7.56 µg/m3, 0.03 – 2.82 µg/m3, 0.16 – 1.11 µg/m3, 0.32 – 1.02 µg/m3, 1.32 – 3.34 µg/m3, and 0.15 – 2.07 µg/m3 for iron, manganese, nickel, lead, zinc and vanadium, respectively. There was statistical dissimilarity (P < 0.05) across study stations for nickel, iron and zinc, and no significant variation (P>0.05) for manganese, vanadium and lead. Pollution indices and index of geoaccumulation showed low to moderate contamination. The overall risk index reveals a low hazard. The enrichment factor and principal components analysis showed the metals are from anthropogenic and natural sources. Zinc correlates strongly with iron, manganese and nickel, an indication that these metals are from similar sources. The carcinogenic and non - carcinogenic hazards were within the threshold limits of 10-6 to 10-4 and