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
Heavy metal pollution in wetland ecosystems poses serious threats to aquatic biodiversity and human health, particularly in agricultural regions with limited environmental monitoring. This study assesses the distribution, sources, and health risks of eight trace metals: lead (Pb), cadmium (Cd), chromium (Cr), manganese (Mn), nickel (Ni), mercury (Hg), copper (Cu), and zinc (Zn) in the Khaliajury haor, a critical wetland in Netrokona, Bangladesh. From June to December 2024, samples of surface water, sediment, and ten commonly consumed fish species were collected across five sampling stations following standard QA/QC procedures. Metal concentrations were compared with national and international guidelines, and source identification was performed along with pollution indices (Igeo, PLI, PER) and health risks (THQ, HI, CR). In surface water, Mn and Cu exceeded permissible limits at all stations. Cr and Hg in sediment surpassed the toxicity reference value (TRV) at every site, while Cd, Ni, and Cu were elevated at multiple locations. However, negative Igeo values and PLI scores below 1 indicated uncontaminated sediment status with low potential ecological risk (PER). In fish tissues, Mn exceeded maximum allowable concentrations (MAC) in seven of ten species, followed by Pb in five species, and Cr and Cd each in two species. Although THQ and HI values remained below 1, suggesting negligible non-carcinogenic risk, cancer risk (CR) values for Pb, Cd, Cr, and Ni exceeded the USEPA upper acceptable threshold of 10⁻4 across all species, implying potential lifetime carcinogenic risk to consumers. Multivariate analysis (correlation matrix and PCA) displayed that bioaccumulation of heavy metals sourced from agricultural runoffs, anthropogenic activities, wastewaters and environmental processes, that travel through different trophic levels in the wetland system. These findings underscore the need for systematic biomonitoring, source identification, and risk communication for communities dependent on haor fisheries.
The pollution of soil by potentially toxic elements in industrial–agricultural transition zones threatens global food security and public health owing to their persistence and bioaccumulation. This study focused on Miyi County, Sichuan (China), a typical region with intensive vanadium–titanium magnetite mining and modern agriculture, and systematically analyzed eight heavy metals and metalloids (Cd, Hg, As, Pb, Cr, Cu, Zn, and Ni) across the categories of atmospheric deposition, irrigation water, agricultural inputs, and soil–crop systems. A rigorous four-stage full-chain diagnosis (concentration–load–ecology–health) was executed to evaluate pollution levels and pathways. The single-factor pollution index identified cadmium (Cd) as the primary pollutant, exhibiting a maximum index of 32.63. The Håkanson potential ecological risk index (RI) demonstrated that Cd was the absolute dominant contributor, reaching a catastrophic single-element risk factor (Ei) of 2191.8 and contributing over 70% to the comprehensive ecological risk. Spatially, soils displayed a distinct point-source cluster diffusion pattern: the northern metallurgical zone was dominated by a Cr-Zn-Cu-Ni industrial assemblage, while the southern zone was enriched in Cd, Pb, As, and Hg. Positive matrix factorization (PMF) source apportionment quantitatively demonstrated that industrial emissions via atmospheric deposition were the primary driver, contributing 55–75% of the total soil exogenous inputs, while agricultural sources (livestock manure and legacy arsenic pesticides) exacerbated localized accumulation. While overlying irrigation water remained safe, channel sediments acted as historical pollution sinks. The human health risk model revealed that children in industrial core areas faced unacceptable carcinogenic hazards, with a lifetime carcinogenic risk (LCR) reaching 5.6 × 10−4. These highly specific multi-media findings support a macro spatial risk zoning and source interception strategy to decouple economic growth from regional food safety degradation in global transition economies.
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.
This study evaluated the accumulation and potential health risks of five heavy metals – Arsenic (As), mercury (Hg), thallium (Tl), palladium (Pd), and antimony (Sb) in the carrots grown in two regions of Kosovo. The authors analyzed soil and carrot samples to determine how much metal was in them. Then, the bioaccumulation factor (BAF), estimated daily intake (EDI), hazard risk index (HRI), and total hazard index (THI) for both adults and children were established. The findings indicated that the BAF values for As, Hg, Tl, and Pd were predominantly low, signifying minimal translocation from soil to edible carrot tissues, whereas Sb demonstrated moderate bioaccumulation. Children had higher EDI values because they weighed less, and As and Sb were the main sources of dietary exposure. The HRI values for all metals were below 1 for adults, indicating a minimal non-carcinogenic risk; however, children showed notably higher HRI values, especially for arsenic. The THI assessment indicated that overall exposure remained within safe limits for most municipalities; nonetheless, Obiliq recorded the highest THI figures (7.22 for adults, 22.66 for children), highlighting the necessity for regional monitoring. In conclusion, the research demonstrated that carrot consumption in the assessed regions is generally safe for adults, while children may face elevated yet still acceptable levels of exposure. These results offer vital information for food safety evaluations and stress the importance of ongoing monitoring of heavy metal pollution in agricultural soils and crops.
This study investigated the accumulation and ecological risk of heavy metals in soils surrounding a major open dumpsite adjacent to the New Abattoir in Akerebiata Harmony Estate, Ilorin, Southwestern Nigeria. Ten representative soil samples were collected at 9 m by 45 m intervals and analyzed using Atomic Absorption Spectroscopy (AAS) to determine concentrations of Copper (Cu), Zinc (Zn), Chromium (Cr), Iron (Fe), Cadmium (Cd), Cobalt (Co), Arsenic (As), Lead (Pb), Silver (Ag), and Mercury (Hg). Environmental impact was evaluated through the calculation of the Geo-accumulation Index (Igeo), Contamination Factor (CF), Pollution Index (PI), Enrichment Factor (EF), Hazard Quotient (HQ), Hazard Index (HI), and Cancer Risk (CR). Results indicated that while absolute concentrations remained below current regulatory limits, the site is moderately to strongly polluted (PI = 3.37) due to significant anthropogenic inputs. Igeo values showed that the area is uncontaminated regarding Cr, Hg, and Cd, but moderately contaminated with Co and As. The HQ and HI values for all metals were below 1.0 for both children (HI = 0.0016) and adults (HI = 0.0002), indicating no immediate non-carcinogenic risk via soil ingestion. Total cancer risk (CR = 2.08 × 10⁻8 for children) fell within the acceptable range (< 10⁻⁶). However, trends in As, Co, and Hg contamination factors warrant precautionary monitoring. Principal Component Analysis (PCA) attributed PC1 (34.73% variance) primarily to geogenic Fe–Cr inputs and PC2 (24.52%) to anthropogenic Cu-As loading. These findings suggest that the current open dumping system poses a growing risk to the local ecosystem and public health. The study recommends the implementation of engineered sanitary landfills, regular environmental monitoring, and remediation strategies to mitigate future heavy metal accumulation.
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