Integrated analysis of elemental speciation, source apportionment, and pollution risk assessment attributable to PM2.5 exposure in Faridabad, India

The Songhua River represents one of the seven major river systems in China. It flows through Harbin city with 66km long, locating in the northern China with a longer winter time. This paper aimed to study concentration distributions, stability, risk assessment, and source apportionment of heavy metals including chromium (Cr), cadmium (Cd), lead (Pb), mercury (Hg), arsenic (As), copper (Cu), zinc (Zn), and nickel (Ni) in 11 selected sections of the Songhua River Harbin region. Results showed that Cr, Cd, Pb, Hg, and As exceeded their respective geochemical background values in sediments of most monitoring sections. Compared with other important rivers and lakes in China, Cr, Hg, Cd, and As pollutions in surface sediments were above medium level. Further analysis of chemical speciation indicated that Cr and As in surface sediments were relatively stable while Pb and Cd were easily bioavailable. Correlation analysis revealed sources of these metals except As might be identical. Pollution levels and ecological risks of heavy metals in surface sediments presented higher in the mainstream region (45° 47.0' N~45° 53.3' N, 126° 37.0' E~126° 42.1' E). Source apportionment found Hejiagou and Ashi River were the main contributors to metal pollution of this region. Thus, anthropogenic activities along the Hejiagou and Ashi River should be restricted in order to protect the Songhua River Harbin region from metal contamination.

In order to illustrate pollution characterization, source apportionment, and risk assessment of VOCs in Beijing, Baoding, and Shanghai, field observations of CO, NO, NO2, O3, and volatile organic compounds (VOCs) were conducted in 2019. Concentrations of VOCs were the highest in Beijing (105.4 ± 52.1 ppb), followed by Baoding (97.1 ± 47.5 ppb) and Shanghai (91.1 ± 41.3 ppb). Concentrations of VOCs were the highest in winter (120.3 ± 61.5 ppb) among the three seasons tested, followed by summer (98.1 + 50.8 ppb) and autumn (75.5 + 33.4 ppb). Alkenes were the most reactive VOC species in all cities, accounting for 56.0%, 53.7%, and 39.4% of ozone formation potential in Beijing, Baoding, and Shanghai, respectively. Alkenes and aromatics were the reactive species, particularly ethene, propene, 1,3,5-trimethylbenzene, and m/p-xylene. Vehicular exhaust was the principal source in all three cities, accounting for 27.0%, 30.4%, and 23.3% of VOCs in Beijing, Baoding, and Shanghai, respectively. Industrial manufacturing was the second largest source in Baoding (23.6%) and Shanghai (21.3%), and solvent utilization was the second largest source in Beijing (25.1%). The empirical kinetic modeling approach showed that O3 formation was limited by both VOCs and nitric oxides at Fangshan (the suburban site) and by VOCs at Xuhui (the urban site). Acrolein was the only substance with an average hazard quotient greater than 1, indicating significant non-carcinogenic risk. In Beijing, 1,2-dibromoethane had an R-value of 1.1 × 10-4 and posed a definite carcinogenic risk.

Zinc hydrometallurgy sites are critical hotspots for combined toxic metal(loid)s (TMs) pollution, yet the integration of spatial heterogeneity and migration dynamics into source apportionment remains underexplored. This study investigated the concentrations, speciation, and spatial distribution of nine TMs (As, Cd, Cu, Hg, Mn, Ni, Pb, Sb, Zn) in soils at an abandoned zinc smelter in southwest China. Multivariate statistical methods and the Positive matrix factorization (PMF) model were applied to disentangle primary sources and secondary redistribution. Spatial analysis revealed that As, Cd, Cu, Pb, Sb, and Zn shared similar contamination patterns, concentrated in slag storage and comprehensive recovery areas, whereas Hg and Mn exhibited distinct hotspots near sulfuric acid production and electrolysis zones. Vertical migration was most pronounced for Cd and Zn (> 8m depth), followed by Hg and Mn (4-8m), while As, Cu, Pb, and Sb were restricted to 0-4m due to adsorption in clay-rich layers. Speciation analysis indicated high mobility of Cd and Zn (acid-soluble fraction: 66.96 and 52.10%, respectively), contrasting with reducible Pb and Mn (51.59 and 48.32%) and residual As, Hg, Ni, Sb (60.74-76.64%). The results from PMF model identified aqueous-phase (Cd, Zn, Mn) and solid-phase (As, Cu, Pb, Sb) migration pathways, validated by spatial correlations with topography and functional zones. Aqueous-phase contributions dominated low-lying areas, while solid-phase contributions aligned with elevated regions, reflecting topography-driven redistribution. This study advances source apportionment of TM in soil by unifying spatial heterogeneity, speciation dynamics, and receptor modeling, offering a framework for targeted risk assessment and remediation of industrial sites.

Accurately identifying pollution risks and sources is crucial for regional land resource management. This study takes a certain coastal county in eastern China as the object to explore the spatial distribution, pollution risk, and source apportionment of heavy metals in topsoil. A total of 633 samples were collected from the topsoil with a depth ranging from 0 to 20 cm, which came from different topographical and land use types (e.g., farmland, industrial areas, and mining areas), and the concentrations of HMs and As were measured by using atomic fluorescence spectrometry and inductively coupled plasma mass spectrometry. Firstly, the spatial distribution of soil HMs (Cd, Cr, Hg, Ni, and Pb) and arsenic (As) was predicted by incorporating environmental variables strongly affecting soil formation into geostatistical methods and machine learning approaches. Then, various pollution indicators were employed to conduct pollution evaluations, and potential ecological risk assessments were implemented based on the generated soil map. Finally, source apportionment was conducted using random forest (RF), absolute principal component score–multiple linear regression (APCS-MLR), correlation analysis, and spatial distribution of soil HMs and As. Findings in this research reveal that the RF approach yielded the best spatial prediction performance (0.59 ≤ R2 ≤ 0.73). The Nemerow and geoaccumulation indices suggest that various pollution levels exist in this area. The average concentrations of As, Hg, and Ni are 7.233 mg/kg, 0.051 mg/kg, and 27.43 mg/kg respectively, being 1.14 times, 1.27 times, and 1.15 times higher than the background levels, respectively. The central–northern region presented a slight potential ecological risk, with Hg and Cd being identified as the primary risk factors. Natural, agricultural, transportation, and industrial and mining activities were identified as the main HMs and As sources. These findings will assist in the design of targeted policies to reduce the risks of HMs and As in urban soil and offer useful guidelines for soil pollution research in similar regions.

In Antarctica, low temperatures favor the trapping and deposition of polycyclic aromatic hydrocarbons (PAHs), whereas the biogeochemical cycling of PAHs on the Southern Ocean adjacent to Antarctica is highly sensitive to climate change. However, very little environmental and ecological information is available on interannual PAHs variations in the surface of the Southern Ocean. From 2022 to 2024, we employed the 38 th , 39 th , and 40 th Chinese National Antarctic Research Expeditions (CHINARE) to collect surface water samples and conduct analyses of the spatio-temporal distribution patterns, source apportionment, and probabilistic ecological risk assessment of the 16 USEPA priority PAHs. We found that ∑PAH concentration in the study area ranged from 427 to 5782 pg/L, with median values of 1795, 1736, and 2559 pg/L for the 38 th , 39 th , and 40 th expeditions, respectively, showing a latitudinal gradient pattern of higher concentrations at lower latitudes and lower concentrations at higher latitudes. A significant concentration rebound was observed in the 40th expedition. Integrated analysis using molecular diagnostic ratios, PCA, and PMF revealed that this rebound was driven by a distinct “dual-pressure pattern”: intensified logistical traffic emissions (combustion sources) and the persistent release of fresh, unweathered PAHs. Source apportionment indicated an evolutionary trend from mixed petrogenic and ship-related liquid fuel combustion (38th) to episodic fresh local inputs (39th), culminating in the complex superposition of sources in the 40th survey. Probabilistic risk assessment using Monte Carlo simulations confirmed that acute risks to plankton remain low (the 95th percentile of ∑RQ MPC was 0.077); However, a structural shift towards hydrophobic high-molecular-weight PAHs (increasing to ~18% in 2024) signals a rising hidden potential for biomagnification in keystone species like Euphausia superba . These findings provide a critical scientific baseline for identifying pollution sources and supporting Antarctic ecosystem management under changing environmental conditions.

Multimodel-based quantitative source apportionment and risk assessment of soil heavy metals: A reliable method to achieve regional pollution traceability and management

The identification and effective control of pollution sources is essential because heavy metal pollution in agricultural soil is associated with food safety and public health. Industrial wastewater, waste gas, and residues generated from pharmaceutical manufacturing are important sources of heavy metal pollutants in soil, but the research of their risk for surrounding agricultural soil is inadequate. In this study, the typical pharmaceutical manufacturing complex and its surrounding farmland in Hubei Province, China was employed to systematically and comprehensively assess its environmental risk and source apportionment. The results revealed the potential risk of cadmium (Cd), lead (Pb), arsenic (As), and mercury (Hg) from pharmaceutical production for farmland soil around, and among these heavy metals, As and Cd were observed to have the higher pollution level. The accumulated Cd and As had contribution to a series of risks, including comprehensive pollution risk, geo-accumulation risk, potential ecological risk, and the carcinogenic and non-carcinogenic risk. Positive matrix factorization (PMF) source analysis combining with the geographic distribution of heavy metal surrounding pharmaceutical manufacturing confirmed that there were three main heavy metal pollution sources, including pharmaceutical wastewater, traffic, and agricultural chemicals, which had the 52.37%, 16.49%, and 31.14% contributions to the surrounding agricultural soil. The present study provided systematic strategies of environment risk assessment and source apportionment, and can be referred for casual analysis and prevention strategies for farmland soil surrounding pharmaceutical manufacturing complex.

Century-scale evolution of heavy metal speciation and content in Lake Chaohu sediments driven by human activities

Heavy metals are released into the sediments in aquatic environment from both natural and anthropogenic sources and they are considered as worldwide issue due to their deleterious ecological risks and food chain disruption. In this study, sediments samples were collected at three major sites (Awoye, Abereke and Ayetoro) along Ondo coastal marine area using VanVeen grab sampler. The concentrations of As, Cd, Cr, Cu, Fe, Mn, Ni, Pb, V and Zn were determined by employing Atomic Absorption Spectroscopy (AAS). The combined concentrations data were subjected to Positive Matrix Factorization (PMF) receptor approach for source identification and apportionment. The probable risks that might be posed by heavy metals in the sediment were estimated by potential and integrated ecological risks indices. Among the measured heavy metals, Fe had the average concentrations of 20.38 ± 2.86, 23.56 ± 4.16 and 25.32 ± 4.83 µg/g at Abereke, Awoye and Ayetoro sites, respectively. The PMF resulted in identification of four sources of heavy metals in the sediments. The resolved sources and their percentage contributions were oil exploration (39%), industrial waste/sludge (35%), detrital process (18%) and Mn-sources (8%). Oil exploration activities and industrial wastes are the major sources that contribute heavy metals into the coastal sediments. The major pollutants that posed ecological risks to the local aquatic ecosystem are As, Pb, Cr and Cd (40 ≤ $$E_{r}^{i}$$ < 80) classifying the sites as moderate risk. The integrate risks values of Awoye, Abereke and Ayetoro are 231.2, 234.0 and 236.4, respectively suggesting that the study areas had a moderate ecological risk. The study showed the suitability of PMF receptor model for source identification of heavy metals in the sediments. Also, the intensive antropogenic activities and natural sources could largely discharged heavy metals into the study area, which may increase the heavy metal contents of the sediments and further contribute to the associated ecological risk, thus affecting the local aquatic ecosystem.

Industrial development has caused significant environmental damage, especially through potentially toxic element (PTE) pollution. Combining pollution indices, health risk assessment, spatial autocorrelation (Moran's I), and receptor modeling (APCS/MLR), this study quantified sources and risks of heavy metals in smelting-adjacent farmland soils, facilitating targeted PTE pollution mitigation. Soil analysis revealed significantly elevated mean concentrations of As (326mg/kg), Cd (23mg/kg), Cr (104mg/kg), Cu (106mg/kg), Ni (73mg/kg), Pb (274mg/kg), and Zn (660mg/kg), all exceeding Yunnan provincial background values. The average total non-carcinogenic risk index (HIadult = 2, HIchild = 11) and total carcinogenic risk index (TCRadult = 5.52 × 10-4, TCRChild = 6.44 × 10-4) for both adults and children exceeded the threshold (HI = 1, TCR = 1 × 10-04). The results of environmental pollution evaluation show that the overall pollution in the study area is a heavy pollution level. The ACPS-MLR model showed that Cd and Zn in soil mainly came from industrial activities (37%). Cu and Pb were derived from motor vehicle emissions and agricultural activities (20%). As may be derived from agricultural and industrial activities. Furthermore, based on the combination of source apportionalization and the spatial distribution of environmental pollution, the northeastern part of the study area and transportation hubs are the key pollution areas and need to be given priority for treatment. PTEs accumulate in the soil, will be enriched through the food chain, and seriously threaten human health and soil ecological environment. Therefore, this study can provide a basis for identifying, preventing, and controlling the risk of PTEs pollution in soil.

Traditional risk assessment and source apportionment of sediments based on bulk polycyclic aromatic hydrocarbons (PAHs) can introduce biases due to unknown aging effects in various sediments. We used a mild solvent (hydroxypropyl-β-cyclodextrin) to extract the bioavailable fraction of PAHs (a-PAHs) from sediment samples collected in Pearl River, southern China. We investigated the potential application of this technique for ecological risk assessments and source apportionment. We found that the distribution of PAHs was associated with human activities and that the a-PAHs accounted for a wide range (4.7%–21.2%) of total-PAHs (t-PAHs), and high risk sites were associated with lower t-PAHs but higher a-PAHs. The correlation between a-PAHs and the sediment toxicity assessed using tubificid worms (r = −0.654, P = 0.021) was greater than that from t-PAH-based risk assessment (r = −0.230, P = 0.472). Moreover, the insignificant correlation between a-PAH content and mPEC-Q of low molecular weight PAHs implied the potiential bias of t-PAH-based risk assessment. The source apportionment from mild extracted fractions was consistent across different indicators and was in accordance with typical pollution sources. Our results suggested that mild extraction-based approaches reduce the potential error from aging effects because the mild extracted PAHs provide a more direct indicator of bioavailability and fresher fractions in sediments.

Speciation analysis is a field of trace element analytical chemistry that deals with detection, identification and determination of individual chemical forms of metals and metalloids. There has been increased awareness of the importance of elemental speciation over the last 20 years and this has lead to growing demand for analytical techniques capable of providing species-specific information. Hyphenated Techniques in Speciation Analysis offers a brief but comprehensive overview of hyphenated techniques and their various applications for the determination of chemical forms of trace elements. It brings a succinct presentation of the concept of speciation analysis, gives an overview of techniques based on coupling of chromatography with element and molecule specific detection and summarises their applications in the fields of environmental and industrial chemistry, biochemistry, nutrition, toxicology and medicine. Fully referenced, Hyphenated Techniques in Speciation Analysis is an invaluable introduction to elemental speciation analysis and also provides a practising analyst with a critical overview of research carried out in the field.

The multiple sources and concomitant negative environmental and health impacts of volatile organic compounds (VOCs) in the atmosphere demonstrate their importance in air pollution control. This study employed environment- and health risk-oriented source apportionment methods to quantitatively estimate VOCs’ contribution to air pollution and health risks, using offline VOC measurements from the Harbin urban region from 2021 to 2022. Total volatile organic compounds (TVOCs) averaged 25.6 ± 8.2 ppb, except for alkanes (34.4%), and aromatics (24.2%) were found to be a major contributor, with the highest LOH (38.0%), ozone formation potential (OFP) (43.0%), and secondary organic aerosol formation potential (SOAFP) (95.0%) and exerting a directly toxic effect (46.0%). Positive matrix factorization (PMF) source apportionment revealed that vehicle exhausts, combustion sources, solvent and coating usage, solvent and fuel evaporation, and petrochemical industry sources were key VOC sources. A health risk assessment showed that there was an integrated carcinogenic risk of 5.8 × 10−4, with respiratory (1.5 × 10−4) and hematologic systems (1.5 × 10−4) representing higher carcinogenic risks. Both benzene and naphthalene exhibited carcinogenic risks of 1.5 × 10−4, implying an excess of higher cancer risk levels (1.0 × 10−4). Significant joint environmental and health benefits could be obtained by reducing benzene and naphthalene concentrations by about 50.0%, along with the abatement of vehicle exhausts (82.6%), combustion sources (40.7%), and solvent and coating usage (50.7%). This study can serve as useful guidance for the quantitative mitigation of hazardous VOCs and their key sources.

This study investigates pollution levels, source apportionment, ecological, and human health risks associated with toxic metals (Pb, As, Hg, Cr, and Cd) in road dust from the most populated Dhaka city and a connected major highway in Bangladesh. The mean concentration of Pb, Hg, and Cd were 1.3, 29.3, and 13.2 times higher than their corresponding background values with spatially uneven distribution all over the study area. Metal pollution indices, the geo-accumulation index (Igeo), NIPI, and PI, indicated extreme contamination at many sites depending on local environmental factors. The potential ecological risk ([Formula: see text] revealed that 84% and 54% of samples showed the extreme ecological risk for Hg and Cd pollution, respectively. On the other hand, the potential ecological risk index (PERI) and Nemerow integrated risk index (NIRI) showed that most sampling sites suffered high to extreme ecological risk. Source apportionment using positive matrix factorization (PMF) identified coal combustion, and gasoline (50.14%), traffic exhaust (35.26%), and industrial and agriculture activity (14.60%) were the main source of toxic metals of the study area. Non-carcinogenic health risk indicated that adults are more vulnerable than children, and hazard index (HI) of Hg for both age groups and Cd for adults were significantly higher than the safe level. The carcinogenic risk (CR) levels of toxic metals were acceptable (10-6 to 10-4), although the maximum limit of Cr for children and As for adults was close to the unacceptable limit (10-4). Continual exposure to toxic metals through road dust might develop lifetime cancer risk in local inhabitants.

This study proposes a systematic approach to characterize heavy metal (HM) contamination and conduct source-oriented risk assessment in agricultural soils surrounding a smelter in Henan Province. The pollution status was evaluated by determining local geochemical baseline concentrations (GBCs), with values for Cr, Ni, Zn, Cu, Cd, and Pb being 28.91, 14.75, 39.6, 18.30, 0.63, and 37.34 mg·kg−1, respectively. The pollution levels of individual metals followed: Cd > Pb > Cu > Zn, with an overall assessment indicating moderate contamination. Four sources were identified through Geographic Information System (GIS) spatial analysis and positive matrix factorization (PMF): smelting sources (31.1%), mixed livestock-agricultural sources (15.3%), natural sources (33.7%), and traffic sources (19.9%). Ecological and health risks were quantified using PMF-based risk assessment models. The ecological risk (ER) index was as high as 175.48, primarily driven by smelting sources (70.63%) and Cd. Noncarcinogenic risk (NCR) was mainly attributed to smelting sources (39%) and Pb, whereas carcinogenic risk (CR) was primarily contributed by natural sources (78%) and Ni. The probability of carcinogenic risk exceeding the acceptable threshold is 100%, potentially linked to the local cancer incidence rate. Therefore, regulating smelting activities and controlling low-concentration yet high-risk metals (Ni and Cd) are crucial for effective environmental management.