Histological Lesions in Gills of Feral Cyprinids, Related to the Uptake of Waterborne Toxicants from Keenjhar Lake

Mitigating marine hazardous contaminants: A sustainable management perspective

Marine hazardous contaminants, such as cadmium (Cd) and lead (Pb), pose significant risks to both human health and aquatic organisms. Traditional methods may not remove contaminants to safe levels, leading to the release of hazardous materials into marine environments. This research proposes polymeric membrane bioreactors as a potential solution to this problem. We determined Cd and Pb levels in three freshwater fish species (Rita, Ompok bimaculatus, and Heteropneustes fossils) from two distinctive regions (Zone 1 and Zone 2). Additionally, Cd and Pb concentrations in feeding materials, water, and sediments were analyzed to estimate daily intake and potential hazardous effects of these contaminants on the fish species. These findings underscore the need for effective regulatory measures and policies to reduce the discharge of hazardous contaminants into freshwater and marine environments, protecting both human health and the environment. Implementing polymeric membrane bioreactors in wastewater treatment and industrial facilities could mitigate the risks associated with consuming contaminated fish species. Significantly, the Cd and Pb levels in all three fish species from both fishponds exceeded the Food and Agriculture Organization's (FAO) maximum permissible limits. These findings carry important implications for policymakers, regulators, and industries, urging them to act appropriately to ensure the safety of the environment and public health. This study suggests that polymeric membrane bioreactors are a promising technological approach to address marine contamination, emphasizing their potential role in safeguarding human health and aquatic ecosystems.

Health risks associated with accumulation of heavy metals in fish of Keenjhar Lake, Pakistan

The Keenjhar Lake in the southern part of Pakistan is exposed to heavy metal contamination, mainly due to the lack of proper upstream industrial effluent treatment. In this study, accumulation of heavy metals in five frequently consumed fish species Cirrhinus mrigala (Morakhi), Labeo rohita (Kur'ro), Solea solea (Mundi), Sperata seenghala (Singharo), and Anguilla bengalensis (Baam) from Keenjhar Lake were investigated. A total of 30 fish samples were collected from fishermen at the lake. Fish tissues were digested using standard methods and analyzed for metals using an atomic absorption spectrophotometer (AAS). Heavy metal (Cu, Ni, Pb, total Cr, Cr(VI), and Cd) concentrations were detected both in fish muscles and liver. Among the five targeted species, Cirrhinus mrigala appeared to be the most bioaccumulative fish, with Cr (219.78) > Pb (34.20) > Cu (22.49) > Ni ((16.24) > Cr(VI) (15.25) > Cd (0.01). The target hazard quotient (THQ) and hazard index (HI) were calculated to assess human health risk. The concentration of metals showed a significant difference among fish muscles and liver in the three studied locations. The total HI for heavy metals were estimated to be less than 1, but the cancer risk (CR) for Pb and Cr(VI) exceeded acceptable limits for fish consumption. From the human health perspective, this study informs local populations, i.e., fishing communities and population consuming approximately 150 g/day of Keenjhar Lake fish regularly are chronically exposed to Pb and Cr(VI) contamination with (10-⁴ to 10-⁶) carcinogenic risks.

Cadmium and Lead Hazardous Impact Assessment of Pond Fish Species

The current study aims to assess the concentration of cadmium (Cd) and lead (Pb) in five tissues of Cirrhinus mrigala, Labeo rohita, and Catla catla collected from fishponds of Jamshoro and Larkana, Sindh, Pakistan. Meanwhile, the levels of Cd and Pb in feeding materials, water, and sediments of fishponds of both areas were also studied. The daily intake and hazardous impact assessment of Cd and Pb by muscles of three fish species of fishponds of both areas were estimated. The concentration of Cd in tissues of C. mrigala and C. catla of Larkana were higher than that in tissues of same fish species of Jamshoro whilst Pb contents in tissues of fishes of Jamshoro were high (p > 0.05). The feeding materials of fishponds of Larkana were enriched with Cd whilst Pb was high in feeding material of fishponds of Jamshoro. The estimated bioaccumulation factor, average daily intake, and hazardous quotient of Pb were high as compared to Cd in all studied fish species of fishponds of Larkana and Jamshoro. The hazardous quotient of Pb indicated that the local population of both areas might have a potential toxic risk. Graphical abstract ᅟ.

Analysis of Some Trace Metals in Fish Species after Preconcentration with Congo Red on Amberlite XAD-7 Resin by Flame Atomic Absorption Spectrometry

A new procedure for separation and preconcentration of trace amounts of Cu(II), Ni(II), Fe(III), Zn(II), Cr(III), Cd(II), and Pb(II) in fish samples was proposed. The procedure is based on the adsorption of these metal ions on the column of Amberlite XAD-7 as congo red complexes prior to their determination by flame atomic absorption spectrometry (FAAS). Several factors that can affect the sorption and elution efficiency of the metal ions were investigated and optimized. The sorption was quantitative in the pH range of 6.0–9.0 for Cu(II) and Ni(II), 5.5–8.0 for Fe(III), 6.0–8.5 for Zn(II) and Cd(II), and 7.0–8.5 for Cr(III) and Pb(II). The optimum pH for simultaneous retention was 7.5. The sorption capacity of the resin was found to be 0.89, 0.72, 0.82, 0.61, 0.53, 0.84, and 0.78 mg/g for Cu(II), Ni(II), Fe(III), Zn(II), Cr(III), Cd(II), and Pb(II), respectively. The precision of the method was evaluated as the relative standard deviation obtained by analyzing a series of six replicates and below 6% for all seven elements. The validation of the method was performed by the analysis of certified reference materials. The proposed method was successfully applied to separation/preconcentration and determination of these metals in fish samples.