A nationwide investigation on the characteristics and health risk of trace elements in surface water across China

Metal contamination in the Ashtamudi Wetland ecosystem: Source identification, toxicological risk assessment of Ni, Cd, Cr, and Pb and remediation strategies

This study examines the presence of potentially toxic elements (PTEs) in the surface sediments and water of the Ashtamudi wetland, a Ramsar site on India's southwest coast. The average concentration of PTEs in water(μg/L) and in sediments (mg/kg) follows the order Fe(147.89) > Zn(107.53) > Cu(5.73) > Pb(4.57) > Mn(4.41) > Ni(3.07) > Cr(2.98) > Cd(0.32) > Co(0.14) and Fe (37,311.91) > Mn (341.59) > Zn (147.97) > Cr (88.07) > Ni (74.24) > Cu (42.23) > Pb (30.84) > Co (15.61) > Cd (1.85) respectively. Contamination and ecological risk indices (e.g., EF, CF, Igeo, mCd, EI, RI, mHQ, TRI, PLI) reveal moderate to considerable ecological hazards and contamination. Health risk assessments identify elevated cancer risks associated with Ni, Cd, Pb, and Cr in high-contamination zones. Statistical tools (PCC, PCA, and HCA) elucidate pollution sources and sediment dynamics, showing that urban runoff and industrial discharge are the major contributors. In contrast to previous studies, this work integrates seasonal variations, advanced risk indices health risk assessments and remediation techniques, which are critical for sustainable management. The findings thus call for targeted remediation strategies to mitigate heavy metal contamination and safeguard the ecological integrity and public health of Ashtamudi Wetland.

Assessment of pollution and health risks from exposure to heavy metals in soil, wheat grains, drinking water, and atmospheric particulate matter

Heavy metal pollution is a global environmental issue that poses serious threats to human health. In the Bian East Industrial Cluster Zone of Kaifeng City, prolonged sewage irrigation and industrial activities have led to severe heavy metal contamination in various environmental media and crops. However, the health risks posed by heavy metals in different environmental media in this area are yet to be assessed. Thus, we measured the concentrations of multiple heavy metals in samples from different environmental media (soil, drinking water, and atmospheric particulate matter) and crops (wheat grains). A health risk assessment model was used to evaluate the health risks posed by heavy metals through different exposure pathways and estimate the contribution of each medium and heavy metal to multi-media comprehensive health risks. The results indicated that in most sample sites within the study area, the soil was contaminated with Cu, Zn, Cd, Pb, As, and Hg, whereas atmospheric particulate matter contained elevated levels of Cr and Cd. However, the heavy metal contents in the wheat grains and drinking water did not exceed national standards. Health risk assessment revealed high levels of non-carcinogenic and carcinogenic risks (multi-media total hazard index, MTHI >1; multi-media total carcinogenic risk, MTCR >10⁻⁴) in the study area. The primary sources of these risks were atmospheric particulate matter and wheat grains. Among the heavy metals, Cr, Cu, and Zn mainly posed non-carcinogenic risks, while Cr and Cd primarily posed carcinogenic risks. These findings highlight the need for focused attention in controlling heavy metal pollution in atmospheric particulate matter and wheat grains. This study provides a theoretical basis for managing and preventing heavy metal pollution in various environmental media to ensure food production safety and protect public health in the study area.

Identifying the pollution risk pattern from industrial production to rural settlements and its countermeasures in China

Impacted by large-scale and rapid rural industrialization in the past few decades, China's rural settlements are confronted with the risk of heavy metal pollution stemming from industrial production, which might pose a significant threat to the rural habitat and the well-beings. This study devised a relative risk model for industrial heavy metal pollution to the rural settlements based on the source-pathway-receptor risk theory. Using this model, we assessed the risk magnitudes of heavy metal pollution from industrial production at a 10 km × 10 km grid scale and identified the characteristics of the risk pattern in China. Our finding reveals: (1) the relative risk values of wastewater, waste gas and total heavy metal pollution are notably concentrated within a confined spectrum, with only a small number of units are characterized by high-risk level; (2) Approximately 21.57 % of China's rural settlements contend with heavy metal pollution, with 4.17 %, 9.84 % and 7.55 % being subjected to high, medium and low risks, respectively; (3) The high-risk units mainly is concentrated in the developed areas such as Yangtze River Delta, Pearl River Delta, and the Beijing-Tianjin metropolitan area, also dispersed in the plain areas with high rural population density. Guided by these insights, this study puts forth regionally tailored prevention and control strategies, as well as distinct process prevention and control strategies.

Natural background level, source apportionment and health risk assessment of potentially toxic elements in multi-layer aquifers of arid area in Northwest China

Groundwater contaminated by potentially toxic elements has become an increasing global concern for human health. Therefore, it is crucial to identify the sources and health risks of potentially toxic elements, especially in arid areas. Despite the necessity, there is a notable research gap concerning the sources and risks of these elements within multi-layer aquifers in such regions. To address this gap, 54 phreatic and 24 confined groundwater samples were collected from an arid area in Northwest China. This study aimed to trace the sources and evaluate the human health risks of potentially toxic elements by natural background level (NBL), positive matrix factorization (PMF) model, and health risk model. Findings revealed exceeding levels of potentially toxic elements existed in phreatic and confined aquifers. Source apportionment and NBL results indicated that mineral dissolution, evaporation, redox reactions, and human activities were the main factors for elevated concentrations of potentially toxic elements. High Fe and Mn concentrations were attributed to reduction environments, while F accumulation resulted from slow runoff, and irrigation from the Yellow River. Due to high F levels, more than one-third of groundwater samples (phreatic: 33.14 %, confined: 56.22 %) posed non-carcinogenic health risks to population groups. Adults displayed higher carcinogenic risks (phreatic: 19.47 %, confined: 34.16 %) than infants (phreatic: 0 %, confined: 0 %) and children (phreatic: 1.26 %, confined: 7.97 %) owing to the toxic elements of Cr. The confined aquifer presented greater health risks than the phreatic aquifer. Consequently, controlling the levels of F and Cr in multi-layered aquifers is key to reducing health risks. These findings provide valuable insights into protecting groundwater from contamination by potentially toxic elements in multi-layered aquifers worldwide.

A Copula-based spatiotemporal probabilistic model for heavy metal pollution incidents in drinking water sources

Water pollution incidents pose a significant threat to the safety of drinking water supplies and directly impact the quality of life of the residents when multiple pollutants contaminate drinking water sources. The majority of drinking water sources in China are derived from rivers and lakes that are often significantly impacted by water pollution incidents. To tackle the internal mechanisms between water quality and quantity, in this study, a Copula-based spatiotemporal probabilistic model for drinking water sources at the watershed scale is proposed. A spatiotemporal distribution simulation model was constructed to predict the spatiotemporal variations for water discharge and pollution to each drinking water source. This method was then applied to the joint probabilistic assessment for the entire Yangtze River downstream watershed in Nanjing City. The results demonstrated a significant negative correlation between water discharge and pollutant concentration following a water emergency. The water quantity-quality joint probability distribution reached the highest value (0.8523) after 14 hours of exposure during the flood season, much higher than it was (0.4460) during the dry season. As for the Yangtze River downstream watershed, five key risk sources (N1-N5) and two high-exposure drinking water sources (W3-W4; AEI=1) should be paid more attention. Overall, this research highlights a comprehensive mode between water quantity and quality for drinking water sources to cope with accidental water pollution.

Health impact assessment of the surface water pollution in China

China suffers from severe surface water pollution. Health impact assessment could provide a novel and quantifiable metric for the health burden attributed to surface water pollution. This study establishes a health impact assessment method for surface water pollution based on classic frameworks, integrating the multi-pollutant city water quality index (CWQI), informative epidemiological findings, and benchmark public health information. A relative risk level assignment approach is proposed based on the CWQI, innovatively addressing the challenge in surface water-human exposure risk assessment. A case study assesses the surface water pollution-related health impact in 336 Chinese cities. The results show (1) between 2015 and 2022, total health impact decreased from 3980.42 thousand disability-adjusted life years (DALYs) (95 % Confidence Interval: 3242.67-4339.29) to 3260.10 thousand DALYs (95 % CI: 2475.88-3641.35), measured by total cancer. (2) The annual average health impacts of oesophageal, stomach, colorectal, gallbladder, and pancreatic cancers added up to 2621.20 thousand DALYs (95 % CI: 2095.58-3091.10), revealing the significant health impact of surface water pollution on digestive cancer. (3) In 2022, health impacts in the Beijing-Tianjin-Hebei and surroundings, the Yangtze River Delta, and the middle reaches of the Yangtze River added up to 1893.06 thousand DALYs (95 % CI: 1471.82-2097.88), showing a regional aggregating trend. (4) Surface water pollution control has been the primary driving factor to health impact improvement, contributing -3.49 % to the health impact change from 2015 to 2022. It is the first city-level health impact map for China's surface water pollution. The methods and findings will support the water management policymaking in China and other countries suffering from water pollution.

Metal pollution assessment in the surface sediments of a river system in Türkiye: Integrating toxicological risk assessment and source identification

This study investigates potentially toxic elements (PTEs) in the surface sediments of the Abdal River system, a critical water source for Samsun province, Türkiye, due to the presence of the Çakmak Dam. PTE concentrations, measured in mg/kg, show significant variability: Hg (0.03) < Cd (0.26) < As (10.98) < Pb (13.88) < Cu (48.61) < Ni (62.45) < Zn (70.97) < Cr (96.28) < Mn (1015) < Fe (38357). Seasonal variations were observed, in particular increased concentrations of As, Cd and Pb in summer (p < 0.05). Contamination and ecological risk indices (mHQ, EF, Igeo, CF, PLI, Eri, mCd, NPI, PERI, MPI, and TRI) indicate moderate to low levels of contamination, suggesting potential ecological effects. Health risk assessments suggest minimal risks to human health from sediment PTEs. Statistical analyses (PCC, PCA and HCA) improve the understanding of the sediment environment and contamination sources, while the coefficient of variation assists in source identification.

Heavy metals in centralized drinking water sources of the Yangtze River: A comprehensive study from a basin-wide perspective

Water quality in the Yangtze River Basin (YRB) has received considerable attention because it supplies water to 400 million people. However, the trends, sources, and risks associated with heavy metals (HMs) in water of centralized drinking water sources (CDWSs) in the YRB region are not well understood due to the lack of high-frequency, large-scale monitoring data. Moreover, research on the factors affecting the transportation of HMs in natural water are limited, all of which significantly reduce the effectiveness of CDWSs management. Therefore, this study utilized data on 11 HMs and water quality from 114 CDWSs, covering 71 prefecture-level cities (PLC) in 15 provinces (cities), to map unprecedented geospatial distribution of HMs in the YRB region and examine their concentrations in relation to water chemistry parameters. The findings revealed that the frequency of detection (FOD) of 11 HMs ranged from 28.59% (Hg) to 99.64% (Ba). The mean concentrations are ranked as follows: Ba (40.775 μg/L) > B (21.866 μg/L) > Zn (5.133 μg/L) > V (2.668 μg/L) > Cu (2.049 μg/L) > As (1.989 μg/L) > Mo (1.505 μg/L) > Ni (1.108 μg/L) > Sb (0.613 μg/L) > Pb (0.553 μg/L) > Hg (0.002 μg/L). Concentrations of Zn, As, Hg, Pb, Mo, Sb, Ni, and Ba exhibited decreasing trends from 2018 to 2022. Human activities, including industrial and agricultural production, have led to higher pollution levels in the midstream and downstream of the river than in its upstream. Additionally, the high concentrations of Ba and B are influenced by natural geological factors. Anion concentrations and nutrient levels, play a significant role in the transport of HMs in water. Probabilistic health risk assessment indicates that As, Ba, and Sb pose a potential carcinogenic risk. Additionally, non-carcinogenic risk to children under extreme conditions should also be considered.

Water Quality and Associated Human Health Risk Assessment Related to Some Ions and Trace Elements in a Series of Rural Roma Communities in Transylvania, Romania

This research aims to assess the content of some ions and trace elements in water sources in 24 rural Roma communities in Transylvania in order to assess the human health risk associated with exposure to such elements and ions. To this end, eight ions (F-, Cl-, Br-, NO2-, NO3-, SO42-, PO43-, NH4+) and ten trace elements (Cr, Ni, As, Pb, Cd, Mn, Cu, Zn, Fe, and Hg) were determined in 71 water samples by ion chromatography coupled with a conductivity detector for ions and atomic absorption spectrophotometry for all trace elements. General parameters were also determined. Non-conformity (as number of samples), according to the EU Drinking Water Directive, was observed as follows: pH (7), EC (7), hardness (1), oxidizability (15), Cl- (4), NO3- (30), SO42- (6), Fe (16), Mn (14), As (3), and Ni (1 sample). The incidence of ions was Cl- (71), SO42- (70), F- (67), NO3- (65), NH4+ (21), Br- (10), PO43-, and NO2- (1 sample) and for trace elements, Mn (59), Fe (50), As (38), Ni (32), Cu (29), Zn (28), Cd (12), Cr (11), and Pb (3 samples). Hg was not detected. Non-carcinogenic (HI) values exceeded one for As in 13 Roma communities, with higher values for children than for adults. For NO3-, the HI values were >1 in 12 for adults and 14 communities for children. The carcinogenic risk (CR) for As through ingestion ranged from 0.795 to 3.50 × 10-4 for adults and from 1.215 to 5.30 × 10-4 for children. CR by dermal contact was in the range of ×10-6 both for adults and children.