Element Contamination Research Articles

Assessment of trace elements contamination and human health risk based on Monte Carlo simulation in a karst groundwater system affected by industrial activities.

Groundwater in karst regions is a vital drinking water source, but it is highly susceptible to contamination from industrial activities, which exacerbate pollution and pose health risks. This study investigated the concentration, spatial distribution, quality, health risks and sources of trace elements (TEs) in groundwater within a newly established industrial park in Guiyang, a representative city with a karst landscape. The results indicated that the trace element concentrations followed the order: Ti > Fe > Al > Ni > Cr > Mn > V > Cu > As > Co. Correlation Analysis (CA) and Hierarchical Cluster Analysis (HCA) suggested that the sources of TEs are multifaceted, with industrial activities identified as the primary influencing factor. Monte Carlo simulations revealed that the non-carcinogenic risk (NCR) associated with each element was negligible. However, due to industrial activities, Cr, Ni and As exhibited significant carcinogenic risks. As one of the characteristic pollutants of the electroplating industry, Cr presented the highest potential risk. The total carcinogenic risks (TCR) for adults and children were 3.24E-05 and 3.78E-05, respectively, both exceeding the acceptable risk threshold of 1E-06. These results make a meaningful contribution to the management of vulnerable aquifers in karst industrial areas, with an emphasis on protection against TEs contamination, which is critical for ensuring groundwater safeguard and protecting public health.

Trace element Contamination and Health Risk Assessment from Consumption of Six Commonly Consumed Fish in a Subtropical (Bakkhali River) Estuary

Trace element Contamination and Health Risk Assessment from Consumption of Six Commonly Consumed Fish in a Subtropical (Bakkhali River) Estuary

Spatiotemporal distribution and human health risks of potential toxic elements in the groundwater of the lower Tista Floodplain, Rangpur, Bangladesh

This study assessed the extent of potential toxic element (PTE) contamination and its associated health risks in groundwater from the Tista Floodplain, Rangpur, northern Bangladesh. A total of 130 groundwater samples (65 from the wet season and 65 from the dry season) were analyzed for six PTEs: As, Al, Cu, Mn, Cr, and B using Atomic Absorption Spectrophotometry (AAS) and VIS Spectrophotometry. The mean concentrations of PTEs followed a decreasing order of B > Mn > Cu > Al > As > Cr in the wet season and Mn > B > Al > Cu > As > Cr in the dry season. Metal evaluation index and degree of contamination indicated minor contamination, while the Nemerow pollution index showed moderate to severe contamination, especially in Nilphamari district. Contamination levels were higher in the dry season compared to the wet season. No individual PTEs posed non-carcinogenic health risks, but combined PTEs presented potential health threats, particularly to infants, with higher severity during the dry season. No dermal health risks were identified. Despite the relatively low contamination levels, monitoring policies for new and existing tubewells should be implemented to ensure sustainable groundwater management and long-term water quality.

Molybdenum, lead and zinc mobility potential in agricultural environments: a case study of the Kočani field, North Macedonia

The research focuses on the assessment of potential toxic elements (PTEs) contamination of the soils of the Kočani field (North Macedonia) due to the surrounding past and current polymetallic mining activities. The Zletovska River drains the untreated wastewater from the Pb-Zn mine in the Zletovo-Kratovo region and is unfortunately used to irrigate the surrounding rice fields. Elevated levels of molybdenum (Mo) and especially lead (Pb) and zinc (Zn) were found in the soil samples from the rice fields near the Zletovska River (in the western part of the Kočani field), which are well above the limit and critical emission values for PTEs content in soils. In addition, Mo was consistently bound to water soluble, exchangeable and oxidizable fractions in all samples, while reducible and residual fractions were predominated by Pb and Zn. According to the sum of the water-soluble and exchangeable fractions, the mobility and environmental bioavailability potential of the investigated PTEs in the soil-plant system decreased in the following order: Mo > Pb > Zn. It is therefore very important to emphasize that when assessing the environmental impact of PTEs on the respective surroundings, not only the commonly considered trace and minor PTEs (such as Pb and Zn) that occur in geological materials should be taken into account, but also in lower contents (such as Mo). The translocation of PTEs within the ecosystem does not depend on their total content in the primary geological materials, but on their individual mobility and binding capacity.

Evaluation of Heavy Metal Contamination in Black Soil at Sanjiang Plain: From Source Analysis to Health Risk Assessment

Heavy metals were discharged into the agricultural soil through coal mining, transportation, etc., posing a threat to human health through the food chain. In order to investigate the sources of heavy metals and potential risk to the population, we collected 298 surface soil samples in the black soil area of Sanjiang Plain in Heilongjiang province and tested the concentrations of seven heavy metals. Toxic element contamination in the soil was evaluated by combining the potential ecological risk index and environmental capacity, and pollution sources are identified through positive matrix factorization. The results indicate that the concentrations of Cd and As exceed background values by 1.74 and 1.51 times, respectively, and the ecological risk of Cd is significantly higher than those of other toxic elements. The comprehensive ecological risk level is a moderate comprehensive ecological risk level at 78.5% and a low comprehensive ecological risk level at 21.5%. The sources of heavy metal elements include pesticide spraying (36.5%), input fertilizer and transport activities (20.5%), and mining and metallurgy-related activities (43.1%). When linking the PMF to the Human Health Risk Assessment model, it was found that about 56% of the samples pose a carcinogenic risk to children. Knowledge of soil pollution can certainly help to understand the sources of toxic elements and the health risks to people in the black soil area and provide a scientific basis for the prevention of heavy metal pollution.

Black shale contamination and platinum group elements prospect of the Khandwa basalt, Eastern Deccan Volcanic Province (India) -an experimental approach

An experimental study at one atmospheric pressure was carried out with basalts of the Deccan Traps and black shale as a contaminant to assess the potentiality of the platinum group elements (PGEs) in the contaminated magma. The experiments involved 10%, 15% and 20% black shale as contaminants to understand the incremental concentration in the PGEs. The results show that Pd, Pt, Ru, Rh, Ir and Os substantially rise in the contaminated melt. Though the quantitative increase in the PGE content owing to contamination is evident, the increase is case-specific and related to the degree of black shale contamination, e.g. for Pt, Ru and Pd, 20% contamination yields maximum enrichment, whereas, for Rh and Ir, the maximum increment is obtained for 10% contamination; Os gives most significant increase for 15% contamination. Black shale contaminationleads to the sulfide supersaturation of the basaltic magma and the formation of the PGE-rich sulfide liquid due to immiscibility. The present experimental study revealed a significant role of black shale as a crustal contaminant for the flood basalt and consequent PGE enrichment in the contaminated magma. The findings of this study are important for the other Large Igneous Provinces of the world as well.

Potentially toxic elements contamination and health risk assessment of coastal sediments in Betoya Bay, Morocco.

This study investigated the potentially toxic elements (PTEs) contamination of Betoya Bay surface sediments to assess the degree of pollution and identify the source of these contaminants. Average PTE levels as mg/kg in Betoya Bay are ranked in descending order as Zn (22.68) > Cr (8.64) > Pb (7.24) > Ni (6.82) > As (6.62) > Cu (5.78) > Co (2.45) > Cd (0.20). The sampling sites show an increase in PTEs at station 5, probably due to runoff from the wadi, and at the first station, where fishing activity is particularly intense. At all stations throughout the year, PTE levels were unpolluted as evaluated by the geoaccumulation index (Igeo) and the pollution load index (PLI). Almost all PTEs showed a "low contamination factor" according to the contamination factor index (CF). As assessed by the contamination degree (CD), all PTE levels at all stations and seasons were "low contamination degree". The ecological risk indices (Eir and RI) indicated low to moderate ecological risk. In line with sediment quality requirements, the M-ERM-Q calculation suggests there is only a 9% chance that this particular combination of metals poses a threat. The non-carcinogenic health risk assessment showed that beach sand in the study area is entirely safe, presenting no additional health risk to children or adults. However, the carcinogenic risk showed a low to moderate carcinogenic risk for adults and a moderate to high carcinogenic risk for children. In addition, statistical analysis revealed that all PTEs are likely to have common sources, which may be related to the geology of the area.

Sustainable multiphase jet polishing of additively manufactured heat pipes utilizing recycled glass chips

Each year, a huge amount of waste glass chips is produced by machining, which is not recycled and has been treated as waste, resulting in the wasting of resources. However, the pristine physical properties of these micro-sized chips show great potential to be recycled as abrasives in jet polishing. In this work, machined glass chips were recycled and directly used as the abrasives in multiphase jet (MPJ) and abrasive water jet (AWJ) polishing for aluminum heat pipes of additive manufacturing with complex structures. Polishing performance of the recycled abrasives from waste glass was compared with those of commercial quartz abrasives with mesh sizes of 600, 800, 1000, 1200, and 3000. The results show that the recycled abrasives of glass chips have comparable performance to the commercial abrasives with mesh size of 1000. Computational fluid dynamic simulations were conducted on the two jet polishing to elucidate the fundamental material removal mechanisms. It is found that a higher drag force in the AWJ polishing could lead to uniform material removal and induce four times higher for material removal rate (MRR). The cost of setup, water and energy consumptions of MPJ polishing are only one tenth those of AWJ polishing. Energy dispersive spectroscopy reveals that there is no element contamination on the polished surface. This work proposes a novel approach of MPJ polishing for components produced by additive manufacturing with complicated structures. These findings provide new insights for the recycling use of waste chips generated in manufacturing, and suggest new solutions for saving energy and resources, as well as for clean and green production.

Trace element contaminants and endocrine status of European brown bears assessed using blood as a matrix.

Bioaccumulation of trace element contaminants with endocrine disruptive (ED) potential has been noted in European brown bears, though evidence of their effects is lacking. Generalized linear models were employed to assess circulating levels of reproductive, stress, and thyroid hormones in relation to arsenic (As), cadmium (Cd), mercury (Hg), lead (Pb) and thallium (Tl) in 53 free-ranging brown bears (Ursus arctos) from two European populations (Carpathian and Dinara-Pindos). Other potential drivers of hormone variation, such as essential elements, ecological factors, physiological variables, and capture methods, were included as predictors. The models demonstrated a positive association between cortisol and Cd, and a negative association with Tl. In addition, Tl and Pb were identified as key factors in explaining variation in thyroid hormones (free triiodothyronine, fT3 and free thyroxine, fT4). Trap type was significant in explaining variation in fT3 concentrations, while sex was an important predictor of progesterone levels. The essential elements, cobalt (Co) and copper (Cu) accounted for 41% of testosterone variation, while Cu and selenium (Se) were negatively associated with fT4. Other notable predictors of investigated hormone variation included body condition index (important for cortisol), age (for fT4), year (for fT3), capture day (for fT4 and fT4:fT3 ratio) and population (fT4:fT3 ratio). This study evidenced trace elements as important factors to consider when studying hormonal variation in terrestrial wildlife (Tl for cortisol and fT3, Cd for cortisol, Cu for testosterone and fT4, Co for testosterone, Pb and Se for fT4). To gain a more definitive understanding of the effects of exposure to element contaminants on endocrine status, it is recommended to include more sensitive and specific endocrine disruption-related endpoints in a larger sample size. Doing so will further enhance our understanding of the potential adverse endocrine effects of environmental pollutants on these bear populations and other large mammalian wildlife species.

Use of natural history museum ungulate specimen hair as biomarkers for environmental trace element contamination.

This study reports the first use of natural history museum ungulate specimens' (common fallow deer, bontebok, Arabian oryx, impala, Dall's sheep, water buffalo, and yak) hair as biomarkers for the determination of environmental trace element contamination and public exposure risk factor assessment. Morphological characteristics of the hair, like diameter and protein structure, were determined using optical microscopy and FTIR spectroscopy, respectively. The levels of thirty-nine (39) elements, sixteen (16) rare earth elements (REEs), and selected isotope ratios (52Cr/53Cr, 144Nd/146Nd, 147Sm/149Sm, 173Yb/172Yb, 206Pb/207Pb, and 206Pb/208Pb) in the hair samples were determined by ICP-MS analysis.A NIST 1643e standard reference material was analyzed for method validation to determine the accuracy of the developed elemental analysis method. The average hair diameter found in samples obtained from common fallow deer (193 ± 72µm), bontebok (148 ± 48µm), Arabian oryx (194 ± 40µm), impala (88 ± 20µm), Dall's sheep (240 ± 68µm), water buffalo (139 ± 17µm), and yak (139 ± 16µm) were recorded. 27Al (1642 ± 1551mg·kg-1), 44Ca (506 ± 272mg·kg-1), 56Fe (730 ± 1391mg·kg-1), 24Mg (108 ± 57mg·kg-1), 39K (720 ± 1591mg·kg-1), 28Si (1125 ± 1163mg·kg-1), 23Na (10,223 ± 9824mg·kg-1), and 66Zn (33 ± 25mg·kg-1) have the highest concentrations detected in the hair samples. Potentially toxic elements and REEs have the lowest concentration in the hair samples. The detection of low concentrations of 75As, 111Cd, 59Co, 52Cr, 53Cr, 60Ni, Pb isotopes, and REEs in all hair samples suggests heavy metal contamination. The plausible sources of the detected elements in ungulate animal hair are likely due to dietary intake, anthropogenic activities, environmental contamination, specimens' preservation practices, or a combination of those sources. The figures of merit highlighted by a high correlation coefficient (R2 ≥ 0.9990), low limit of detection (as low as 1.00 × 10-7mg·kg-1 for 140Ce), and high average percent recoveries (97.0 ± 11.5) of the NIST 1643e standard reference material analyses demonstrate the linearity, high sensitivity, and accuracy of the ICP-MS technique for elemental and isotopic analysis of hair samples.

Assessment of heavy metal concentrations, environmental risks and human health implications in marine sediments along the coastal ecosystems of the Republic of Congo.

The aim of this study is to assess the level of heavy metals (HMs) in surface sediments along the coastal estuaries of the Republic of Congo. A variety of approaches were employed, integrating elemental analysis (Atomique Absorption Spectroscopy), environmental, ecological, health risk assessment, and source identification techniques to evaluate the distribution, origin, environmental, ecological and health risks of potentially toxic element (PTE) contamination in sediments. The ascending mean concentration (mg/kg) of Cd (0.4) < Cu (18.6) < Pb (28.8) < Zn (62.1) < Mn (107) < Mg (569.6) complied with the local background, except for Cd and Pb. However, notable variations across sampling points and sites were observed, with a strong relationship between metals and organic matter. The comparing of PTEs with USEPA international standards and sediment toxicity guidelines showed compliance. The assessment of environmental risk parameters, based on the calculation of the geo-accumulation index, concentration factor and pollutant load indices showed low pollution of sediments. The ecological risk assessment, on the other hand, revealed a low level of pollution of biota and a low toxicity risk of ecosystems related to Cd and Pb and then to Cu in some sites. Regarding human health risk assessment, related to the PTEs, the cancerogenic effect indices were calculated for Cd and Pb through ingestion and inhalation pathways, and the non-cancerogenic effect indices were calculated for all HMs through ingestion, inhalation, and cutaneous contact routes, for children and adults, and showed that the results comply with the international standards set by USEPA, ranging from 10-4 to 10-6 and less than 1, respectively, where children were more sensitive and vulnerable than adults to the effects of the PTEs. Ultimately, this study revealed sediment lithology, anthropogenic activities, and mixed origins of HMs, with a large contribution from industrial activities. However, no significant impacts are discernible in the study area. In addition to the importance of this study, it forms part of the region database and could serve as a reference for future monitoring studies, since no data are available in th Congolese coastal environment.

Effects of Rb-Based Mixed Fluxes on Surface Crystal Growth of BaTaO₂N and Photocatalytic Activities

Photocatalytic water splitting has been actively studied from the viewpoint of environmental issues as a method to produce hydrogen, a clean energy source, without using fossil fuels. Oxynitride BaTaO2N is a visible light responsive photocatalyst and is expected to have high energy conversion efficiency for hydrogen production using sunlight. In a previous study, single phase BaTaO2N crystals were successfully grown by the flux method. However, the maximum activity value is only about 500 µmol/h, which is insufficient to produce enough hydrogen for practical use. One of the reasons for this is unoptimized crystal surface, such as crystal face, and lattice defects. Flux method is known as an effective method to control crystal properties, but single flux is difficult to control these crystal properties at the same time. For example, although RbCl flux can reduce defect density by minimizing elemental contamination of BaTaO2N, it is highly volatile and not effective in controlling the crystal surface. Therefore, we considered the use of multiple fluxes at the same time. This allows appropriate modification of factors related to the flux reaction field, such as viscosity, melting point, and solute-solvent interaction, while avoiding elemental contamination. This leads to flexible adjustment of the crystal growth mode, which we believe will bring crystal growth closer to ideal conditions.In this study, the effect of multi-flux on the growth mode and photocatalytic properties of BaTaO2N crystals was investigated. As an example, we report the crystal growth of BaTaO2N using mixed fluxes of RbCl, RbBr, and Rb2CO3. A single RbCl flux provided step-terrace surface structure of the BaTaO2N crystal, while an equimolar mixture of RbCl and RbBr resulted in a flatter and more rounded crystal. The visible-light responsive photocatalytic activity of the BaTaO2N crystals obtained with each flux was evaluated. The photocatalytic H2 evolution value of BaTaO2N grown in RbCl-RbBr mixed flux was about 30% of that grown in RbCl flux. This drastic change in activity may be explained by decrease of active crystal surface, including step-terrace one derived from mixed flux reaction field. We are now investigating the effect of step-terrace structure on photocatalytic activity, by tuning the surface structure using the mixed flux species. In the presentation, we will systematically report fine design of crystal growth, photocatalytic activity, and also the contribution mechanism of the mixed fluxes on them.AcknowledgementThis work was partly supported by the NEDO Green Innovation fund projects, the Strategic Innovation Program (SIP) of the Cabinet Office, and joint research with a company.

(Invited) Replicating the Corrosion Behavior of Steel and Aluminum Alloys at a Coastal Exposure Site: Using an Accelerated Combined-Effects Chamber Simulation (ACES) for Improved Laboratory Corrosion Testing

Although there are numerous test methods for exposing bare and coated metals in a controlled, corrosive environment to determine relative corrosion resistance and coating behavior, the prediction and correlation of corrosion performance of “accelerated exposure tests” in environmental chambers like salt spray (B117) to field environments are not always straightforward. Existing test methods do not address the simultaneous exposure of various atmospheric and environmental conditions that can affect corrosion performance of a bare or coated metal or correlate results of exposure chamber tests with exposure to outdoor atmospheres and with end-user performance. Many investigations have been performed in recent years to clarify the role of environmental and climatic factors in the atmospheric corrosion of commonly used structural metals and coatings as well as simulate their observed corrosion behavior in the laboratory.The first step toward developing better accelerated test methods is to analyze and accurately reproduce these environments in a laboratory setting. To achieve this goal, a new state-of-the-art accelerated combined effects simulation (ACES) exposure chamber has been developed and has undergone testing by the U.S. Air Force Research Laboratory (AFRL) in collaboration with the U.S. Naval Research Laboratory (NRL) to replicate field conditions and corrosion behavior of various alloys, coating systems, and corrosion/environmental sensors. This chamber was built to include more environmental effects than any previous exposure chamber to accurately mimic a field environment that includes temperature and humidity control, ultraviolet (UV), mixed gasses, and actuators to simulate mechanical stresses.The long term objective of this effort was to develop a better method to categorize the environmental severity of field exposure sites in terms of corrosion attack, which will aid in the design of accelerated laboratory test protocols and lifetime prediction for bare metal substrates in coastal environments. Measurements included site specific weather parameters, mass loss of 1018 steel, AA2024-T3 and AA7075-T6, the corrosion characteristics of uncoated aluminum alloys AA2024-T3 and AA7075-T6, and the resulting environmental deposition of salts onto the aluminum alloy exposure coupons.In the present work, the ACES was used to simulate a 90 day exposure environment of bare metal coupons at the NRL-Key West (NRL-KW) outdoor exposure facility (Key West, FL) as well as an “accelerated” version of the environmental exposure period. The resulting corrosion behavior of bare steel and aluminum alloy coupons in the chamber were compared to identical samples exposed at the NRL-KW facility. It was determined that the exposed steel and aluminum alloy coupons in the ACES chamber exhibited statistically similar values in terms of mass loss (Figure 1), and other corrosion parameters such as thickness of material lost, maximum pit depth, pit coverage and pit density to that determined from identical coupons exposed in the field. In addition, scanning electron microscopy and energy dispersive spectroscopy (SEM-EDS) of elemental surface contamination through deposition from salt spray deposits on the field exposed samples were somewhat similar to the ACES chamber exposed samples.The ability to accurately replicate an exposure environment for materials corrosion testing would provide a significant research development and testing platform for bare and coated materials exposed to environments that are variable in nature. The intent of the test protocol is to be specific to a particular exposure environment or dynamically “tunable” to match the particular environment in which the coating or alloy substrate is intended to be used in service. Any test protocol developed using this system could allow a reasonable prediction of performance lifetime based upon an accelerated test in a relatively short timeframe. Figure 1

Green Synthesis and Characterization of Silver Nanoparticles from Minthostachys acris Schmidt Lebuhn (Muña) and Its Evaluation as a Bactericidal Agent Against Escherichia coli and Staphylococus aureus

The search for new synthesis methodologies based on the principles of green chemistry has led to various studies for the production of silver nanoparticles (AgNPs) using extracts from different parts of plants. Based on this, the present study aims to carry out green synthesis (biosynthesis), characterization, and antibacterial evaluation of reduced and stabilized silver nanoparticles (AgNPs) with aqueous extracts of Minthostachys acris in a simple, ecological, and environmentally safe manner. The extraction process of the organic components is performed using two methods: immersion and the agitation of the leaves of Minthostachys acris Schmidt Lebuhn (Muña) at 0.1% for different times (0.5, 1, 3, 6, and 10 min). Compounds such as hydroxycinnamic acid derivatives, quinic, caffeic, rosmarinic acids, and flavonols present in the Muña extract facilitate the formation of AgNPs; this compounds act as a coating and stabilizing agent. The bioactive components from natural resources facilitate the formation of AgNPs, partially or completely replacing the contaminating and toxic elements present in chemical reagents. The biosynthesis is carried out at room temperature for pH 7 and 8. The synthesized AgNPs are characterized by UV-visible spectroscopy to identify the surface plasmon resonance (SPR) band, which shows an absorption peak around 419 nm and 423 nm for pH 7 and p.H 8, respectively, and Fourier-transform infrared spectroscopy (FTIR) to identify the possible biomolecules responsible for bioreduction and stabilization, with a peak at 1634 cm−1. Dynamic light scattering (DLS) shows the hydrodynamic size of the colloidal nanoparticles between 11 and 200 nm, and scanning electron microscopy (SEM) reveals monodisperse AgNPs of different morphologies, mostly nanospheres, while Laser-Induced Breakdown Spectroscopy (LIBS) demonstrates the presence of Ag in the colloidal solution. The evaluation of the bactericidal activity of the AgNPs using the disk diffusion method against Escherichia coli (E. coli) and Staphylococus aureus (S.aureus) shows that the synthesized AgNPs have effective antibacterial activity against E. coli for the extracts obtained at 6 min for both the immersion and agitation methods, respectively. The significance of this work lies in the use of bioactive components from plants to obtain AgNPs in a simple, rapid, and economical way, with potential applications in biomedical fields.

Livestock and poultry manure influence thallium accumulation in chili peppers (Capsicum annuum) under complex toxic elements contamination in soil

Long-term mining activities in the mercury-thallium mining area of Lanmuchang, southwestern China, resulting in contamination of surrounding soils with complex toxic elements such as Tl, As, Sb, Hg, and Cd. While manure aids in pollution control and soil fertilization, its impact on Tl bioavailability in soil remains incompletely understood. This study explored the physiological changes and Tl accumulation in Capsicum annuum under combined pollution stress and application of livestock and poultry manure near the Lanmuchang mining area. The results showed that chicken manure promoted Tl accumulation in Capsicum annuum, whereas pig and cattle manure inhibited it, with pig manure exhibiting the strongest inhibitory effect. Both pig and cattle manure reduced the transpiration rate of Capsicum annuum, which decreased the driving force for Tl transport to the plant's upper parts. Additionally, manure increased organic acid secretion in Capsicum annuum roots and decreased soil Eh. This led to a reduction in Tl3+ to the more stable Tl+, which decreased the content of exchangeable Tl form and its activity. Pig manure significantly reduced Tl content in stems, leaves, and fruits by increasing the area of the Casparian bands in Capsicum annuum roots, which hindered Tl accumulation. In contrast, chicken manure had the opposite effect. The findings of this study provide important theoretical support for scientifically guiding agricultural production safety in areas contaminated with the heavy metal Tl.

Ecological and Health Risks from Trace Elements Contamination in Soils at the Rutile Bearing Area of Akonolinga, Cameroon

This study evaluates the concentrations of trace elements (TEs) in soils from the rutile deposit area of Akonolinga, Cameroon, and analyzes the associated health risks. A total of 25 samples were analyzed using flame atomic absorption spectrometry (FAAS). The results show that TE concentrations follow the decreasing order Fe, Ti, Zr, Mn, Cr, V, Ba, Zn, Nb, Ni, Pb, Ga, Cu, Co, Y, Br, and Sn. Pollution indices and the Pearson correlation matrix reveal moderate correlations between Fe and several other TEs, indicating a common origin. Enrichment Factors show significant enrichment in Zr, Nb, and Ti, with notable enrichment in Cr and Co at certain sites. Although the Geo-Accumulation Index indicates no direct contamination and the overall ecological risk is low, the Contamination Factor reveals high levels for Cr, Nb, Ti, and Zr. The carcinogenic risk is moderate, while non-carcinogenic risks are high for children and considerable for adults. These research highlight the potential public health impacts in this mining region and provide essential baseline data for future environmental risk management.

Trace element contamination in three shorebird species migrating through Delaware Bay, New Jersey: arsenic, mercury and selenium are increasing.

Many shorebird populations are declining, and contaminants may be partly contributing to the decline by interfering with feeding, migration, and breeding success. The goal of our study was to determine whether there was a temporal change in concentrations of trace elements of red knot (Calidris canutus rufa), sanderling (Calidris alba), and ruddy turnstone (Arenaria interpres) during spring migration in Delaware Bay, New Jersey, USA. We sampled blood to 1) determine levels of trace elements in 2019, 2) compare 2019 trace element levels with those from shorebirds in 2011-2012, and 3) examine variability in blood levels of trace elements among species. In 2019: 1) trace element levels were significantly different among species (except cadmium[Cd]), 2) Cd was lowest in all species, and arsenic (As) and selenium (Se) were highest, and 3) sanderlings had the highest levels of As and Se, and knots had the highest levels of chromium (Cr) and lead (Pb). Se was higher in these shorebirds than reported for other shorebirds from elsewhere. As, mercury (Hg), and Se increased significantly between 2011-2012 and 2019 in all three species. There were no significant temporal changes in Cd. Chromium (Cr) decreased in knots and sanderling. The temporal increases in As, Se, and Hg bear watching as they are toxic in vertebrates, and each can decrease the toxicity of the others. The data indicate that shorebirds can be bioindicators of changing trace element levels in estuaries, potentially providing early warning of increasing levels of As, Hg, and Se in the environment.

Spatial distribution, ecological and human health risks of potentially toxic elements (PTEs) in river Ravi, Pakistan: A comprehensive study

Significant quantities of potentially toxic elements have been and are still being discharged into Pakistan's rivers through natural sources and anthropogenic activities. The present study provides a comprehensive study of potentially toxic element contamination in the water and sediment of the Ravi River, Pakistan. The research aims to examine the extent of pollution, its ecological risks, and the potential human health impacts through detailed geospatial analysis and statistical correlation. Water and sediment representative samples were taken and analyzed for potentially toxic elements, including Cobalt (Co), Cadmium (Cd), Zinc (Zn), Nickel (Ni), Arsenic (As), Chromium (Cr), Lead (Pb), Copper (Cu), and Manganese (Mn). Various pollution indices, such as the “Geo-accumulation Index (Igeo), Modified degree of Contamination (mCd), Nemerow comprehensive pollution index (Pt), Contamination factor (CF), Enrichment factor (EF), Pollution Load Index (PLI), and Potential Ecological Risk Index (PERI),” were calculated to determine the contamination levels and ecological risks. The results indicated significant spatial variability in metal concentrations, with higher levels observed in industrial and urban areas (near Lahore). Cd and As were identified as the most critical pollutants, exhibiting high Igeo, CF, EF, and PERI values. The PLI revealed that several regions along the river are heavily polluted. Pt shows high comprehensive pollution near Lahore and moderate to high pollution in surrounding areas. According to mCd, most of the study area, especially sampling points near Lahore, ranges between 8 and 16, indicating a high degree of pollution. The Human Health Risk (HHR) assessment, considering ingestion, inhalation, and dermal contact pathways, highlighted that children are particularly vulnerable, showing higher Hazard Quotient (HQ) and Hazard Index (HI) values for several metals. Correlation analysis revealed significant relationships between certain metals, suggesting common sources of contamination, likely from industrial discharges and urban runoff. The comprehensive mapping and statistical analysis underscore the urgent need for implementing effective pollution control measures to mitigate the risks posed by potentially toxic element contamination in the Ravi River. This study provides critical insights for policymakers and environmental managers to prioritize areas for remediation and to develop strategies to protect both ecological and human health in the region.

Stuck in the mangrove mud: The risk of trace element exposure to shore crabs in restored urban mangroves

The restoration of mangroves in urban environments can increase the risk of contaminant exposure and subsequent health effects to resident biota, yet this risk is rarely considered in mangrove restoration programs. Here we assessed the influence of sediment chemistry on contaminant bioaccumulation in shore crabs from restored and natural mangroves in urban environments compared to a reference site. The concentrations of some trace elements were several-fold higher in the sediment and crab tissues of the urban restored site compared to the natural reference site (Cd = 6×, Co = 7×, Cr = 4×, Mn = 30×, and Ni = 18× greater in sediments, while Cd = 4×, Co = 2×, Cr = 2×, Mn = 6×, and Ni = 3× greater in crab tissues). NMR-based metabolomics on crabs revealed higher abundances of proline and glutamate at urban sites, which may be indicative of physiological stress from trace element contamination. Choice experiments were used to test habitat selectivity by crabs from each population, and showed that crabs avoided sediments from the contaminated urban sites. Our results suggest that restoring mangroves in contaminated environments could create ecological sinks, where animals take residence in the new habitat but are exposed to sediment-based contaminants, with potential implications for organism and population health.

Investigating soil physicochemical factors influencing trace element contamination at the semi-urban-rural home gardening interfaces on the Fiji Islands

Due to its ecological and public health implications, home gardening soil pollution is challenging. However, the physicochemical factors of trace element pollution in semi-urban-rural home gardening soil interfaces in Fiji are unclear. Self-organizing map (SOM), chemometrics, compositional data analysis (CDA), and soil quality indices were used to evaluate spatial patterns, contamination characteristics, sources, and factors affecting trace element contamination in 55 soil samples from semi-urban and rural Fiji. The average contents of diethylenetriaminepentaacetic acid (DTPA)-extractable forms of trace element levels (mg/kg) increased in rural areas as Fe (55.7) > Mn (40.4) > Zn (9.4) > Cu (5.9) and semi-urban areas as Fe (55.2) > Zn (35.9) > Mn (37.1) > Cu (16.1). Rural soils have less ecological risks to home gardening than semi-urban soils. SOM and CDA analysis showed four spatial clusters: clusters 1 and 3 are natural geogenic in rural regions while clusters 2 and 4 are human-induced non-point sources in semi-urban areas. Principal component analysis (PCA) and hierarchical cluster analysis showed that semi-urban Cu-Zn was more affected by manufacturing emissions or fertilization, whereas rural Fe-Mn was more likely to be lithogenic. The research found that pH and organic matter significantly affect Cu and Zn pollution in semi-urban soils (p < 0.05). For rural and semi-urban soils, trace element subsets explained 44 %–87 % of soil contamination changes using the stepwise regression model. These findings aid to establishing a primary database of eco-environmental risks and facilitate comprehensive strategies for assessing soil contamination and potential threats to food safety.