Risk assessment and source identification of toxic metals in some commonly consumed fishes from a subtropical wetland system: Implications and monitoring.

Ecological Risk Assessment of Heavy Metals in Soils and Surface Waters of Oil-Producing Areas in Akwa Ibom State, Nigeria

Aim: This study assessed the ecological risk posed by six heavy metals [lead (Pb), zinc (Zn), nickel (Ni), copper (Cu), chromium (Cr), and cadmium (Cd)] in soils and surface waters. Study Design: Soil samples were collected at two depths (0–15 and 15–30 cm) from 12 stations across Onna, Mkpat Enin, Eastern Obolo, and Uyo in Akwa Ibom State. Surface-water samples were also collected, and Uyo served as the reference location. Methodology: Composite soil samples were collected using a stainless-steel soil auger. Following acid digestion, metal concentrations were determined by atomic absorption spectrophotometry (AAS). The contamination factor (CF), degree of contamination (C-deg), geoaccumulation index (Igeo), single-metal ecological risk factor, and comprehensive potential ecological risk index (RI) were calculated using average-shale background values and the methods of Müller and Hakanson. Results: Except for nickel at Onna Station 3 (57.5 mg/kg), which exceeded the adopted agricultural and residential soil guideline values, soil-metal concentrations were below the relevant limits. In surface water, lead and nickel exceeded the adopted WHO guideline values at all four locations, whereas chromium and cadmium exceeded the guidelines at two locations. Most CF and Igeo values indicated low contamination, although cadmium showed the greatest relative enrichment at several stations. Conclusion: Although several stations, including the reference location, showed moderate-to-considerable single-metal risk from cadmium, RI remained below 150 at all soil stations, indicating low overall potential ecological risk. The results provide baseline information for environmental monitoring and remediation prioritisation in the studied oil-producing areas.

Potentially toxic element contamination in water and sediments of the Ergene river basin (Türkiye): ecological and human health risk assessment

Assessment of heavy metals and radionuclides pollution in an agro-mining river system: implications for environmental and human health

This study assessed heavy metal (Cu, Ni, Pb, Zn and Cd) and radionuclide (²²⁶Ra, ²³²Th and ⁴⁰K) pollution and associated risks in the Likuyu River system, Tanzania. Surface water and sediments were collected from five sites along a 22.7 km river stretch, while soils and leafy vegetables were sampled from adjacent farms. Heavy metals were analysed by atomic absorption spectrometry and radionuclides by high-purity germanium gamma spectrometry. Risk assessment used contamination factor (CF), geoaccumulation index (Igeo), pollution load index (PLI), bioaccumulation factor (BAF), non-carcinogenic risk, carcinogenic risk (CR), annual effective dose (AED), radium equivalent activity (Raeq), annual ingestion dose (Ding) and excess lifetime cancer risk (ELCR). Heavy metals in river water were below detection limits and complied with WHO drinking-water limits: The Zn, 3–5 mg L⁻¹; Cd, 0.003 mg L⁻¹; Ni, 0.07 mg L⁻¹; Cu, 2.0 mg L⁻¹; and Pb, 0.0135 mg L⁻¹. The Ni in sediments at Sites A and E reached 32.1 ± 26.90 and 35.97 ± 6.51 mg kg⁻¹, respectively, exceeding the threshold effect concentration of 22.7 mg kg⁻¹ but remaining below the probable effect concentration of 48.6 mg kg⁻¹. Pollution indices indicated generally low sediment contamination, with CF values mostly below 1, Igeo values from −5.49 to −0.40, and PLI values from 0.077 to 0.251, although slight Zn enrichment occurred at Site A (CF = 1.14). Soils were weakly polluted, with PLI values of 0.078–0.105; however, Site SOD showed localized Ni enrichment, with CF = 1.577 and Igeo = +0.07, reaching 107.2 ± 1.40 mg kg⁻¹, exceeding the TBS limit of 50 mg kg⁻¹. Bioaccumulation results showed strong Zn uptake in napa cabbage (BAF >12), cowpea (BAF ~8) and okra (BAF ~6), and Pb accumulation in okra (BAF ~6) and cowpea (BAF ~5), whereas Ni and Cd had BAF

Integrated Assessment of Heavy Metal Accumulation in Urban Trees and Soils and Associated Non-carcinogenic Health Risks in Sabzevar, Iran

Assessment of heavy metals and human health risk in shrimps collected from different farms at City of Mati, Davao Oriental

Heavy metals are naturally occurring elements whose concentrations may increase due to anthropogenic activities, posing risks to ecosystems and human health. This study investigated the concentrations of cadmium, chromium, iron, lead, manganese, and nickel in water, sediment, and shrimp (tissue and shell) samples from selected farms in Barangays Dahican and Dawan, City of Mati, Davao Oriental, Philippines. Atomic Absorption Spectrometry was used for heavy metal study, and potential non-carcinogenic health risks were assessed using the target hazard quotient (THQ) and hazard index (HI), following the US Environmental Protection Agency guidelines. Results showed that chromium and nickel levels in water from both farms exceeded the allowable thresholds set by the Department of Environment and Natural Resources. In sediments, chromium, iron, lead, and manganese levels in Dahican exceeded World Health Organization (WHO) limits, whereas Dawan showed elevated levels of chromium, iron, and manganese, with nickel surpassing National Oceanic and Atmospheric Administration standards. In shrimp tissue, chromium in Dahican and manganese in Dawan exceeded WHO limits, while iron remained within safe limits. Cadmium, lead, and nickel were either undetected or below detection limits in shrimp tissue and shell samples from both farms. Despite the elevated concentrations of some metals in the samples, the THQ and HI were below one, indicating that long-term, continuous intake of shrimp from the two farms is unlikely to pose any significant health hazards. Nonetheless, continuous monitoring and management of heavy metals in shrimp farming remain essential to prevent future contamination risks and safeguard environmental and public health.

Heavy metal contamination in the Greater Amanzule Wetlands: a public health concern and a threat to seafood provision