Trace Metal Concentrations in Rainwater, Sources, and Health Risks: A Case Study of Hanoi, Vietnam

Appraisal of contamination levels, pollution sources and health risks of trace metals in the groundwater of Southern Pothohar, Pakistan

The contamination of groundwater by trace metals is a significant concern on global scale as it presents direct and indirect hazards to the ecosystem and human health. However, only limited studies have focused on the risks of trace metals’ contamination in major agronomical areas of Pakistan. The present investigation was designed to evaluate the concentrations of selected metals (Mg, K, Ca, Na, Sr, Ag, Li, Zn, Mn, Fe, Co, Cu, Cd, Cr, Pb and Ni) and physicochemical characteristics (EC, pH, TDS, TH, TA, and Cl−) in the groundwater of Southern Pothohar region of Pakistan. Significant seasonal variations in the metal concentrations were detected; average levels of Ni (0.206 mg/L), Cr (0.085 mg/L), Cu (0.038 mg/L), Mn (0.029 mg/L), Ag (0.026 mg/L), and Cd (0.017 mg/L) were comparatively higher in summer, whereas mean values of Ca (9.210 mg/L), Sr (2.181 mg/L), Co (0.195 mg/L), Li (0.033 mg/L), and Zn (0.025 mg/L) showed relatively elevated concentrations in winter. Average contents of Co, Cr, Cd, Pb and Ni were observed to surpass the permissible limits in 37–99% of the samples established by national and international standards. Multivariate statistical analyses revealed that groundwater contamination was predominantly influenced by anthropogenic sources (mostly originating from agricultural waste, domestic waste, combustion processes, industrial effluents and automobile emissions). The Irrigation Water Quality Index (IWQI) value demonstrated that the groundwater is highly suitable for irrigation. Health risk estimation revealed that noncancer risk for Cd, Cr Ni, and Li surpassed the safe limit (HQing > 1) for adults while Pb and Co exceeded the safe limit (1.0) for children and adults in both seasons. Overall, the study indicated more susceptibility of children than adults to noncarcinogenic risks. Additionally, the carcinogenic health risks for nickel, chromium, lead, and cadmium notably exceeded the acceptable threshold of 1.0 × 10− 06, indicating significant lifetime cancer risk linked to these metals in groundwater. The health concerns warrant urgent attention, and immediate actions are necessary to safeguard and improve the groundwater quality in the studied region.

Seasonal and Spatial Assessment of Heavy Metal Contamination in Groundwater in the Republic of Kosovo

Groundwater is vital to subsurface ecosystems and to maintaining water supplies for human and environmental needs. Heavy metal pollution of water bodies poses a significant threat to environmental health and human well-being. In this paper, a detailed spatiotemporal analysis of heavy metal pollution at a network of 35 sampling sites is presented for the summer, autumn, and winter seasons. The water samples were analyzed based on the concentration (μg/L) of eight priority metals, such as Lead (Pb), Mercury (Hg), Cadmium (Cd), Arsenic (As), Chromium VI (Cr-VI), Copper (Cu), Zinc (Zn), as well as Iron (Fe). Measuring contamination levels, identifying space hotspots, and explaining seasonal variations were the key tasks. The results show that Fe, Zn, and Cu concentrations are consistently high across seasons, with mean values ranging from 234.3 to 253.2 µg/L (Fe), 163.2 to 175.6 µg/L (Zn), and 107.0 to 109.2 µg/L (Cu), indicating a widespread geogenic or diffuse source. The most significant seasonal deviation was observed in the fall when there were unusually high levels of Cd and Hg, with mean concentrations reaching 0.476 µg/L and 0.312 µg/L, respectively, suggesting a strong seasonal contamination event or mobilization process. The spatial analysis showed that the locations (e.g., L6, L8, L10, L28, L29) exhibited common hotspots for different metals, with maximum concentrations reaching up to 793.3 µg/L (Fe), 602.3 µg/L (Zn), and 508 µg/L (Cu). Principal Component Analysis (PCA) effectively separated seasonal trends and classified metals into anthropogenic (Pb, Cd, Hg, Cr (VI)) and geogenic/diffuse (Fe, Zn, Cu) groups. The health risk assessment indicated no significant non-carcinogenic risk, although children are more vulnerable, while arsenic levels in winter approached the upper acceptable carcinogenic limit (up to 1.1 × 10−4). Overall, the study highlights the importance of multi-seasonal monitoring by capturing temporally abrupt contamination events and provides a novel integrated framework that combines seasonal analysis, spatial hotspot identification, and multivariate techniques, distinguishing it from conventional single-season or non-integrated studies.

Assessment of Metal Contamination and Human Health Risk in the Buffalo River Estuary, Eastern Cape, South Africa.

Metal contamination in estuarine environments poses environmental and public health concerns, particularly where surface waters support domestic and subsistence uses. This study assessed the seasonal distribution, controlling mechanisms, and non-carcinogenic health risks of selected metals (Mg, Al, Ba, Fe, Mn, and Zn) in the Buffalo River Estuary, Eastern Cape, South Africa. Water samples were collected from 11 stations during wet and dry seasons and analyzed using standard methods. Descriptive statistics, Pearson's correlation analysis, and principal component analysis (PCA) were applied to evaluate metal distribution, inter-element relationships, and dominant controlling processes. Marked seasonal variability was observed, with higher concentrations of Al (97-1708 μg/L), Ba (7.4-29 μg/L), Fe (54-1751 μg/L), Mn (4-116 μg/L), and Zn (4-23 μg/L) during the wet season, while Mg concentrations were elevated in the dry season (10686-851 382 μg/L) relative to the wet season (1056-1313 μg/L). PCA indicated that wet-season metal dynamics were governed by lithogenic and hydrological processes linked to runoff and suspended sediments, whereas dry-season variability reflected sedimentary geochemical controls, redox processes, conservative mixing, and secondary anthropogenic inputs. Non-carcinogenic health risk assessment for Al, Ba, Fe, Mn, and Zn showed Mn as the largest contributor to risk, although cumulative hazard indices for adults (2.19 × 10-2-1.39 × 10-1) and children (8.10 × 10-2-5.01 × 10-1) remained below unity, indicating low health risk. These findings highlight the dominance of seasonal geochemical processes, providing essential baseline data for water-quality management, and underscore the need for continued monitoring to support effective water-resource management.

Source Apportionment and Concentration of Potentially Toxic Elements in Surface Water and Sediments of Okulu-Aleto River, Rivers State, Nigeria

Urbanization and industrial activities continuously introduce potentially toxic elements (PTEs) into the terrestrial and aquatic environments, leading to various health-related challenges. This study evaluates the concentration of PTEs (Cadmium (Cd), Chromium (Cr), Copper (Cu), Nickel (Ni), Zinc (Zn), Lead (Pb) and Iron (Fe)) and sources identification in the surface water and sediment of Okulu-Aleto River, Rivers State, Nigeria. Using the Atomic Absorption Spectroscopic technique, the concentration of the studied PTEs were monitored for 4 surface water and 3 sediment samples. The mean concentration showed that the PTEs descended as Pb (0.126) > Cr (0.122) > Ni (0.061) > Cu (0.051) > Zn (0.039) > Cd (0.005) and all concentrations are within the WHO limit for surface water. The mean concentration descended as Cu (1.482) > Zn (1.215) > Cr (0.265) > Pb (0.119) > Ni ≥ Cd and all concentration are within the WHO limit except Cr across all sampling points and Cu at the upstream sampling point. Multivariate statistical analyses, including Pearson Correlation Coefficient and Principal Component Analysis, identified both lithogenic and anthropogenic sources, with industrial discharges, wastewater inputs, and sand mining activities contributing significantly to contamination. Strong positive loadings of Cr, Cu, Ni, and Pb indicated shared anthropogenic origins, while variations in Fe and Zn suggested mixed sources. Continuous monitoring and integrated pollution management strategies are therefore recommended to safeguard ecosystem integrity and public health.

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

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.

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