Trace Metals Research Articles

Removal of trace Na and K metal ions by resin-grafted crown ether for electronic-grade N-methyl pyrrolidone purification

The semiconductor industry’s rapid evolution necessitates ultra-high-purity N-methyl pyrrolidone (NMP) as an essential electronic-grade solvent. The development of an efficient coordination material to reduce trace metal ions, particularly Na and K metal ions, to below 1 ppb in NMP solution is a significant challenge. To address this, a novel coordination material, St-DVB-g-ACE, has been developed for the removal of Na and K metal ions from NMP. The material was synthesized by grafting 4′-aminobenzo-15-crown-5-ether onto a strong acid gel resin. The resulting St-DVB-g-ACE-3 exhibited excellent coordination performance for Na and K metal ions, with maximum Langmuir adsorption capacities reaching 20,000 μg/g and 33,333 μg/g, respectively. Of particular interest was the ability of St-DVB-g-ACE-3 to reduce all trace metal ions in industrial-grade NMP to below 1 ppb within a fixed bed column, achieving the stringent requirements for electronic-grade NMP at the G3 level. Additionally, the absorbent enhances the purity of NMP from 99.82 % to 99.84 %, indicating that the material is not dissolved and can exist stably in NMP. Its excellent recyclability and reproducibility make it highly practical for industrial use. Density functional theory (DFT) simulation, complemented by spectral analyses, revealed the interaction force and thermodynamic properties between Na and K metal ions and crown ether ring, and illustrated the interaction between anionic sulfonic group (−SO3−) and metal ions. The prepared resin-grafted crown ether adsorbents are highly effective in the thorough removal of trace metal ions from NMP solution, offering a novel and effective method for the production of electronic-grade NMP.

Assessment of persistent and emerging pollutants levels in marine bivalves in the Gulf of Suez, Egypt

Bivalves possess important ecological and economic values. They have been extensively used as bioindicators for both emerging and classical pollutants in the aquatic environment. This study investigates the levels of trace metals, polycyclic aromatic hydrocarbons (PAHs), and organochlorine pesticides (OCPs), alongside microplastic (MPs), in Tridacna maxima, Paphia textile, and Paratapes undulatus, collected from the Gulf of Suez. This work represents the first investigation of MPs in marine bivalves from the Gulf of Suez. MPs were detected in 72% of the specimens examined and four types of MPs were identified. The metal pollution index indicated that bivalves may have long-term toxic effects on human consumers. The results showed minimal hydrocarbon pollution. Diagnostic ratios indicated a combination of pyrolytic and petrogenic sources, with a notable influence from pyrolytic origins. The risk assessment reflected that the levels of certain trace metals, PAHs, and OCP contaminants could present a low risk to human health.

Source-risk and uncertainty assessment of trace metals in surface sediments of a human-dominated seaward catchment in eastern China

Current total concentration-based methods for source attribution and risk assessment often overestimate metal risks, thereby impeding the formulation of effective risk management strategies. This study aims to develop a framework for source-specific risk assessment based on metal bioavailability in surface river sediments from a human-dominated seaward catchment in eastern China. Metal bioavailability was quantified using chemical fractionation results, and source apportionment was conducted using the positive matrix factorization (PMF) model. Risk assessment integrated these findings using two indices: the Potential Ecological Risk Index (PERI) and the Mean Probable Effect Concentration Quotient (mPEC-Q), with uncertainty addressed via Monte Carlo simulations. Results indicated that average total concentrations of Cu, Pb, Zn, Cr, Hg, Cd, and As exceeded their respective background levels by 1.63 to 15.00 times. The residual fraction constituted the majority, accounting for 53.84 % to 77.79 % of total concentrations, suggesting significant natural origins. However, source apportionment revealed a predominant contribution from anthropogenic activities, including industrial smelting, agricultural practices, and atmospheric deposition. The contributions were found to vary between 5.35 % and 40.03 % when the total concentration was adjusted to bioavailable content. Total concentration-based PERI/mPEC-Q assessments indicated high/moderate risk levels, decreasing to considerable/low risk levels with bioavailability adjustment. Hg and Cd were identified as priority metals. Further incorporating source appointment parameters into the risk assessment, industrial smelting was identified as the primary contributor, accounting for 66.06 % of total risk by total concentration and 65.63 % by bioavailability. This underscores the role of bioavailability in mitigating risk overestimation. Monte Carlo simulations validated industrial smelting as a major risk contributor. This study emphasizes the importance of considering bioavailability in the source-risk assessment of sediment-metals, crucial for targeted risk management in urbanized catchment areas.

Spring Water Quality in a Flood-Prone Area of Kampala City, Uganda: Insights Furnished by Sanitary and Limnochemical Data

For millennia, springs have provided water for drinking, domestic use, balneological treatment, liminality rites as well as tourist attractions. Amidst these uses, anthropogenic activities, especially urbanization and agriculture, continue to impair the functionality of springs. With the looming decadal climate change, freshwater springs could be a sustainable source of clean water for the realisation of Sustainable Development Goal 6. This paper presents the results of the sanitary inspection and assessment of limnochemical characteristics and quality of water samples (n = 64) from four freshwater springs (coded SPR1, SPR2, SPR3, and SPR4) in Kansanga, a flash flood-prone area in the African Great Lakes region of Uganda. Each sample was analysed for 17 parameters (temperature, pH, electrical conductivity, turbidity, fluorides, sulphates, chlorides, nitrates, orthophosphates, total dissolved solids, dissolved oxygen, total alkalinity, potassium, sodium, total, magnesium and calcium hardness) following the standard methods. Water quality index (WQI) was calculated to establish the quality of the water samples based on the physicochemical parameters measured. Based on the sanitary risk assessment results, the springs had medium- to high-risk scores, but most water parameters were within the WHO guidelines for potable water, except for nitrates (in SPR1 and SPR2), hardness levels (in SPR2), and dissolved oxygen (in all the samples). Sampling season and location had significant effects on the limnochemistry of the freshwater springs (p < 0.05). The water quality indices calculated indicated that the water from the springs was of good quality (WQI = 50–57), but there was a reduction in water quality during the wet season. The best water quality was recorded in samples from SPR4, followed by those for SPR3, SPR1, and SPR2. These results provide insights into the contribution of floods and poor sanitation facilities to the deterioration of spring water quality in Kansanga, and the need to leverage additional conservation strategies to support vulnerable communities in the area. Further studies are required to establish the risk posed by trace metals and microbes that may contaminate freshwater in the studied springs, especially following flood events.

Incorporating source apportionment and health risk assessment of heavy metals from indoor dust of an industrial area in Dhaka, Bangladesh

A total of 45 deposited dust samples were collected from the preselected 15 households near an industrial area at Savar, Bangladesh. The concentrations of metals were measured by EDXRF spectroscopy and was found at the following trend: Ca > Fe > K > Ti > Mn > Zr > Sr > Rb > Zn > Cu > Pb > Co. The average concentrations of Cu, Zn, Zr, and Pb were found to be higher than that of the soil background values set by Chinese Environmental Protection Administration (CEPA) and the upper continental crust (UCC), while the average concentrations of K, Ti, Fe, and Rb were found to be higher than that of the background values and lower than that of UCC. Alternately, %RSD for some toxic metals (i.e., Fe, Co, Zn and Pb) in the dust samples were ranged broadly (%RSD: 33.54–86.88 %), which indicates that these trace metals might be present in indoor dust samples due to anthropogenic sources, which is consistent with the ANOVA test. In this study, the contamination levels of metals were assessed based on the enrichment factor (EF), pollution load index (PLI), and geo-accumulation index (Igeo). The two ways ANOVA (Fcal = 3.86 >Fcritic = 1.78, df = 14) for EF data had revealed the heterogeneity of metal enrichment in the study area, whereas PLI values were close to 1.0 or > 1, which indicated that the indoor dust samples in the study area might be deteriorated of site quality by the studied metals. The analysis of Igeo also revealed that these dust samples are slightly to extremely polluted. Conversely Pearson correlation analysis, principal component analysis, and cluster analysis were employed to identify the possible sources of such heavy metals, which suggested that the anthropogenic sources are the main sources of the examined heavy elements. Subsequently, the human health risk assessment strategies were applied to identify the routes of exposures based on the US EPA health risk models. For non-cancer effect, ingestion of dust particles is the main exposure route to both the children and adults. The total hazard index (HI) values indicate that both children and adults are vulnerable to non-carcinogenic effect, but children are more vulnerable than adults (tstat = 1.97 >tcritic = 2.039, p = 0.029) at a 95 % confidence level. Nevertheless, no significant carcinogenic health risk due to the presence of Co was found for both children and adults in the study area. According to sensitivity analysis, the ingestion rate (IR) and the concentration of Co posed the most significant impact (> 79.9 %) on cancer risk estimation.

Groundwater quality assessment using revised classical diagrams and compositional data analysis (CoDa): Case study of Wadi Ranyah, Saudi Arabia

This research aims to assess the status and chemical properties of groundwater in the shallow aquifer of the Wadi Ranyah region, Saudi Arabia, using robust statistical methods (CoDA) that take into account the unique characteristics of chemical analysis data from forty-five (45) groundwater samples collected in the Wadi Ranyah valley. A centered logarithmic transformation (clr) approach and isometric logarithmic transformation (ilr) plots for compositional data were utilized to determine the different water types and to understand the hydrogeochemical processes influencing groundwater chemistry in the region. The results of principal component analysis and K-means clustering reveal the existence of three groundwater groupings: (i) The first group occupies the recharge region with a relationship between trace metal elements (F, Pb, Mn, Zn), pH, and TDS, indicating the effect of alteration of igneous and metamorphic rock minerals. (ii) The second group characterizes the downstream part of the Al-Hujrah area with a relationship between calcium and nitrates, indicating the influence of agricultural activities. (iii) The third group, located in the Ranyah area, shows a relationship between major ions (Na+, SO42−, Mg2+, HCO3–, Cl−, K+), which explains water mineralization influenced by silicate weathering and evaporation phenomena. According to the modified Piper diagram (ilr Piper), two hydrochemical facies are identified. The upstream region is categorized as Ca-HCO3– while the downstream region is classified as Na-K-HCO3–. Calculated water quality index (WQI) values indicate that all Wadi Ranyah groundwater samples are of very poor quality (WQI > 300). This is due to higher concentrations of polluting elements (Pb, Mn and F), in particular the high lead concentrations which vary between 0.24 and 0.4 mg/L, and are well above the WHO limit (0.01 mg/L) for consumption of drinking water. The application of CoDA for the first time in the study region has provided a more detailed and reliable assessment of the mechanisms governing groundwater quality, permitting suggestions for the management of groundwater resources and defining future research needs.

Micronutrient availability alters Candida albicans growth and farnesol accumulation: implications for studies using RPMI-1640.

The dimorphic fungus Candida albicans is a major opportunistic pathogen of humans. RPMI-1640 is a chemically defined growth medium commonly used with C. albicans. We identified over 32,000 publications with keywords RPMI and C. albicans. Additionally, Antifungal Susceptibility Testing (AFST) protocols in the United States (CLSI) and Europe (EUCAST) utilize RPMI as a base media to assess drug efficacy against clinical fungal isolates. RPMI contains many nutrients but no added trace metals. We found that the growth characteristics with RPMI were dependent on which MOPS buffer was chosen and the contamination of that buffer by trace levels of Mn(II) and Zn(II). Added Mn(II) was most needed for cell growth while added Zn(II) was most needed for secretion of farnesol and other signaling molecules.

Advanced design of metal single-atom (Pt, Mn, Fe or Cu) loaded S-Ni(OH)2 nanosheets array catalysts to achieve high-performance overall water splitting

Designing catalysts at atomic level fine-tune the electronic structure of surface-active site for efficient water splitting, is a highly desirable approach but also poses significant challenges. This study focuses on the synthesis of a series of electronically tunable metal single-atom (M−SAs) catalysts: M9@S-Ni(OH)2 (M=Pt, Mn, Fe or Cu). Experimental results reveal that introduction of trace S-heteroatoms and metal atoms into Ni(OH)2 lattice can effectively modulate the electronic structure of M9@S-Ni(OH)2 through modulation of p-d and d-d orbital hybridization, resulting in exceptional performance in water electrolysis. Among M9@S-Ni(OH)2, Pt9@S-Ni(OH)2 and Fe9@S-Ni(OH)2 exhibit excellent hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) performance, respectively, the overpotential requiring only 7 mV and 269 mV, respectively, at current density of 10 mA cm−2. (−) Pt9@S-Ni(OH)2||Fe9@S-Ni(OH)2 (+) presents a high current density of 531.07 mA cm−2 at cell-voltage of 1.80 V in overall-water splitting (OWS), which is 14.07 times higher than that of the commercial (−) Pt/C||IrO2 (+) (37.86 mA cm−2) system. This work achieves the development of cost-effective and stable electrocatalysts, offering a solution for large-scale and sustainable water-hydrogen conversion.

Association of multiple trace metals in scalp hair with glioma risk: the mediating role of inflammation

Association of multiple trace metals in scalp hair with glioma risk: the mediating role of inflammation

Characterization of Ash from Tropical Biomass Gasification for Soil Fertilization

This study aims to determine the characteristics of bottom ash from the gasification of four agricultural biomasses namely corn stalks and cobs, cotton stalks, and wood residues, for potential use as agricultural fertilizer. The methodological approach consisted in carrying out gasification trials for each of these biomasses under identical operating conditions on a pilot-scale gasifier. The fly ash was collected at the end of the tests from the reactor bottom and cyclone bottom for analysis. Analysis showed that the ash from the reactor bottom contained higher levels of mineral elements, including Ca, P, K, and Mg in comparison to the cyclone bottom ash. However, the latter exhibited a higher content of Zn. Trace metallic elements (TMEs) were present in relatively low proportions. Ash from the gasification of cotton stalks had the highest Ca, Mg, K, and P content. The TME content was relatively above the required threshold, but it remained below the threshold in the ash from corn stalks. This suggests that cotton stalk ash is more suitable for use in agriculture as a soil fertilizer.

Isolation and Molecular Characterisation of Chlorogonium sp. from Industrial Wastewater

Microalgae are photosynthetic, unicellular microorganisms also known as phytoplankton. They are small plant-like entities. In this research, the sample were collected from cement factory in a sterilised 20L container wrapped with foil paper and were transported down to Federal University, Wukari where it was kept in refrigerator at biochemistry laboratory. Blue-Green media (BG-11) was prepared. Wastewater containing Microalgae obtained from cement wastewater pond were cultivated in BG-11 medium to determine the growth of the organism. BG-11 medium contained macronutrients, trace metals and some vitamins which aid the growth of the organism. The wastewater sample containing with suspected microalgae was inoculated (inoculum ratio = 25%) and incubated under atmospheric CO2 at room temperature (30±2°C) in our laboratory for two to three weeks during the incubation period. In order to purify the isolates, the upper growth layer was first decanted into a freshly produced medium and then plated on BG-11 media that had been solidified with 1% agar-agar. For several of the cultures, growth on the agar plates continued for around three weeks. Following repeated sub-culturing, the emerging greenish colonies were re-emerged into a sterile BG-11 agar medium. In isolation of organism from the industrial cement waste water, the isolate was identified by morphological and molecular identification by extracting the DNA, run the electrophoretic analysis and PCR using primers for 18S rRNA eukaryotic microalgal and then run the sequence analysis. The results of this study obtained, indicated that, the electrophoretic result show the band has 1800-2000base pair and the organism isolated from the industrial cement waste water were chlorogonium sp. with a percent similarity of 78.65% and accession number of OR886595 based on data Gene Bank blast results.

Trace metal distribution in seagrass-vegetated sediments of an urbanized estuary in Queensland, Australia

Seagrasses increase sediment complexity by trapping particulates and influencing biogeochemical cycles via root oxygen loss and organic matter exudation. However, their impact on trace metal sequestration is poorly studied. We found significantly higher trace metal concentrations in seagrass sediments compared to adjacent bare sediments, correlating with total organic carbon, iron, and fine sediments. Sequential extractions showed that most trace metals were dominated by recalcitrant fractions (oxidizable and residual fractions), representing phases such as organic matter, iron sulfides, and crystalline iron oxides. Depth-dependent trends in trace metal partitioning were evident. For example, arsenic in the oxidizable fraction only weakly correlated with Fe in surface sediments (rsp = 0.55) but correlated strongly in deeper sediments (rsp = 0.87), consistent with iron sulfides being a dominant host-phase. Overall, these results suggest that the unique geochemical conditions facilitated by seagrasses play an important role in sequestering trace metals in urban estuarine sediments.

Synergistic neurological threat from Сu and wood smoke particulate matter

Trace metal Cu and carbonaceous airborn particulate matter (PM) are dangerous neuropollutants. Here, the ability of Cu2+ to modulate the neurotoxicity caused by water-suspended wood smoke PM preparations (SPs) and vice versa was examined using presynaptic rat cortex nerve terminals. Interaction of Cu2+ and SPs, changes of particle size and surface properties were shown in the presence of Cu2+ using microscopy, DLS, and IR spectroscopy. In nerve terminals, Cu2+ and SPs per se elevated the ambient levels of excitatory and inhibitory neurotransmitters L-[14C]glutamate and [3H]GABA, respectively. During combined application, Cu2+ significantly enhanced a SPs-induced increase in the ambient levels of both neurotransmitters, thereby demonstrating a cumulative synergistic effect and significant interference in the neurotoxic threat associated with Cu2+and SPs. In fluorimetric measurements, Cu2+ and SPs also demonstrated cumulative synergistic effects on the membrane potential, mitochondrial potential, synaptic vesicle acidification and ROS generation. Therefore, synergistic effects of Cu2+ and SPs on the most crucial presynaptic characteristics and neurohazard of multiple pollutants through excitatory/inhibitory imbalance, disruption of the membrane and mitochondrial potential, vesicle acidification and ROS generation were revealed. Increased expansion and burden of neuropathology may result from underestimation of synergistic interference of the neurotoxic effects of Cu2+ and carbonaceous smoke PM.

Trophic stoichiometry of macroelements and metals in a terrestrial food web

In order to understand the transfer of macroelements and toxic metals in the terrestrial food web, barn swallows, terrestrial frogs, and insects were collected from farmlands in the Leizhou Peninsula, and analyzed for macroelements carbon (C), nitrogen (N), phosphorus (P), and sulfur (S) and trace metals nickel (Ni), zinc (Zn), selenium (Se), copper (Cu), chromium (Cr), cadmium (Cd), lead (Pb), and mercury (Hg). The multi-element ecological stoichiometry was discussed to trace the food web flow of nutrients and toxicants. The percentage contents of C, N, P, and S were 35.43–59.91%, 6.89–12.11%, 0.49–4.66%, and 0.44–2.19%, respectively. The concentrations of Ni, Zn, Se, Cu, Cr, Cd, Pb, and Hg were 0.163–116 mg/kg, 38.7–227 mg/kg, 0.0453–3.82 mg/kg, 3.11–141 mg/kg, not detected—79.6 mg/kg, 0.0203–0.358 mg/kg, 0.148–4.57 mg/kg, and 0.00159–1.46 mg/kg, respectively. Organisms at high trophic levels had higher contents of N, P, and S, and lower contents of C. Significant correlations were observed between δ15N and ratios of C: N, C: P, C: S, N: P, N: S, and S: P, indicating selective transfer of biogenic elements for predators in the terrestrial food web. Most metals including Ni, Zn, Se, Cu, Cr, Pb, and Hg had biomagnification factors and trophic magnification factors higher than 1, because the whole body of organisms rather than tissues were used. The negative correlations between the detoxification ratios of Se: X (each toxic metal) and metal concentrations suggest potential adverse effect of metals on terrestrial organisms.

Radical 6‐Endo Addition Enables Pyridine Synthesis under Metal‐Free Conditions

AbstractMetal‐free synthesis of heterocycles is highly sought after in the pharmaceutical industry and has garnered widespread attention due to eliminating the need to remove trace metal catalysts from the reaction. We report a radical 6‐endo addition method for pyridine synthesis from cyclopropylamides and alkynes under metal‐free conditions. Various terminal and substituted alkynes are inserted as C2 units into cyclopropylamides to synthesize versatile pyridines with 57 examples. Mechanistic investigations and computational studies indicate the unprecedented 6‐endo‐trig addition of vinyl radicals to the imine nitrogen atom rather than the conventional 5‐exo‐trig addition to the imine carbon atom, in which the hypervalent iodine(III) plays a critical role. This reaction easily scales up with excellent functional group compatibility and suits the late‐stage pyridine installation on complex molecules.

Assessing Trace Metal Contamination and Associated Risks in the Kossan River Ecosystem, Southern Côte d'Ivoire

Trace metals accumulate in aquatic systems and can pose a threat to human health and wildlife. In recent decades, human activity has become the main source of metals in the environment. In order to gain a better understanding of metal contamination in Ivorian rivers impacted by human activity, and to help set up a database, we studied the distribution of arsenics (As), cadmium (Cd), copper (Cu), lead (Pb) and zinc (Zn) in the Kossan River. A total of 21 surface water and sediment samples were taken at 7 stations along the River Kossan between March 2019 and July 2020. Total concentrations of the metals were analyzed by atomic absorption spectroscopy (AAS). Carcinogenic and non-carcinogenic risks were assessed in surface water. Contamination indices such as EF, CF; Igeo and PLI were calculated to determine the level of sediment contamination. Ecological risk indices Er and RI were used to assess the potential risks associated with metals. The concentrations of As, Pb, Cd, Cu and Zn found in surface water samples fell within the following ranges: 2.03 - 17.19, 1.752 - 13.264, 0.067 - 0.774, 17.44 - 2369.11 and 136.72 - 3669.37 µg/L, respectively and in sediment: 0.69 - 4.60, 2.10 - 11.30, 0.13 - 5.00, 1.70 - 28.20 and 4.10 - 90.30 µg/g, respectively. The results showed high levels of As, Cu, Pb and Zn contamination in places, above WHO limits. The calculation of non-carcinogenic and carcinogenic risk indices revealed that arsenic and copper can present major health risks for humans through the consumption of water. Cd concentrations exceeded geochemical background values. The results suggest moderate to very severe Cd contamination of the sediments by anthropogenic origin at certain sampling points. In general, the results of the ecological risk indices revealed low to moderate levels of contamination for metals, with the exception of heavy cadmium contamination in the river. The highest concentrations of trace metals were observed in water and sediment samples collected from stations with high anthropogenic pressure. The continuing intensification of human activity may in the long term present a major risk to man and his environment, hence the need to set up a system for monitoring river watercourses and to develop a system for remediating trace metals in river water such as phytoremediation.

Source and health risks of trace metals in Clarias batrachus and Chrysichthys nigrodigitatus from surface waters in Bayelsa State, Nigeria: a probabilistic model

IntroductionHuman activities have inadvertently led to the release of harmful substances, including trace metals, into aquatic environments, with consequential impacts on aquatic organisms and potential health risks for consumers. This research assessed the presence, origins, and health implications of trace elements within the muscles of Clarias batrachus and Chrysichthys nigrodigitatus from the Bomadi and Gbotebo rivers and their surroundings in Bayelsa State, Nigeria.MethodsThirty samples from each fish species were collected and analyzed to conduct the study. Through the use of an atomic absorption spectrophotometer, the researchers determined the concentrations of trace metals, including iron, copper, zinc, lead, nickel, cadmium, and cobalt, in the fish tissues.Results and discussionThe concentrations of the metals within the two fish species varied, with notable differences in zinc and cadmium levels. Utilizing statistical analyses like Pearson correlation, principal component analysis (PCA), and hierarchical cluster analysis (CA), it was established that the trace metals originated from diverse sources. The study then evaluated health risks associated with these trace elements, considering both non-carcinogenic and carcinogenic hazards for different age groups. The results indicated that children’s total target hazard quotient fell below 1 for both fish species, implying a limited tendency toward non-carcinogenic risks through lifelong fish consumption. However, in some adult fish samples, the quotient exceeded 1, indicating a higher potential for non-carcinogenic risks. Regarding carcinogenic hazards, the mean risks were generally lower than the accepted threshold, except for lead in both fish species among adults and children. Stricter values highlighted that only lead concentrations in fish from both categories were deemed acceptable. Consequently, this study highlights the importance of raising awareness among consumers who buy fish from the studied region. Moreover, consistent monitoring of potentially harmful trace elements in water, sediments, and fish is recommended to safeguard consumer health and well-being.

Roe deer exposure to trace metals and pesticides in forests and agricultural plains of North-eastern France.

Human activities related to agriculture and industrial development result in the emission of different types of pollutants in the environment. The phytosanitary pressure depends on the time of the year, the type of habitat, and the used treatments. Wildlife, particularly ungulates, can be exposed to pesticides and trace metals through their herbivorous diet directly impregnated by the environmental contamination. Wild game thus plays a sentinel role but can also represent a risk for human health by exposing venison consumers to these contaminants. The present study explored this dual problem in two types of habitat: forests and agricultural plains located in North-eastern France. Samples of liver and muscle were taken from ten roe deer, five caught on the forests and five others in the plains, to determine contaminant levels. There was no significant difference in contamination of roe deer livers according to the habitat for three trace metals (chromium, nickel, and copper), while lead concentrations were higher in samples from the plain (0.85 vs. 0.74mg·kg-1 dry matter DM; P < 0.01). Conversely, zinc concentrations were higher in forest roe deer (110 vs. 95mg·kg-1 DM; P < 0.05). Cadmium concentrations did not differ significantly between the two habitats, but forest samples showed strong inter-individual variability, with some values close to those observed on the plains and others higher (1.8 vs. 0.3mg·kg-1 DM for forest and plain, respectively; P = 0.11). Mercury was not detected in any sample. The majority of pesticides investigated were not detected. Only a few pesticides were in trace amount (from 1 to 8µg·kg-1 fresh matter), either in the liver (e.g., heptachlor and oxychlordane) or in both tissues, liver and muscle (e.g., pyridalyl). Some compounds were only detected in plain (e.g., cypermethrin and fenpropidin) and others in forest (piperonyl butoxide and pyridalyl) samples. Analyses mainly detected insecticides in samples taken from forests and agricultural plains. Fungicides and a few herbicides were mainly detected in plain sampled animals. Pesticides and copper concentrations in roe deer tissues were lower than maximum residue levels established for farm (copper) or wild terrestrial (pesticides) animals. Cadmium concentrations were also lower than the maximum level for most samples, except for some forest roe deer. However, both forest and plain roe deer exceeded the maximum level for lead in liver. Human exposure was simulated according to different amounts of meat consumed and compared with toxicological reference values. This study highlighted an overall low risk to human health for both pesticides, copper and lead, with more reservations about cadmium for some roe deer shot in forest. The differences in roe deer contamination between forests and agricultural plains for some trace elements and organic pollutants confirmed the sentinel role of this species.

The Impact of Heavy Metal Contamination in Humans and Periodontitis: A Scoping Review.

Periodontal disease, one of the most prevalent diseases worldwide, is a chronic inflammatory disease caused by dysbiotic dental biofilms that trigger the host's immune response. Periodontitis is a type of periodontal disease characterized by the destruction of tissues that support the teeth. The disease is influenced by various systemic and environmental risk factors. As heavy metals have been associated with the development of chronic inflammatory diseases, the present scoping review aimed to determine the coverage of the literature on whether human contamination by heavy metals affects periodontitis, as well as their mechanisms of action. Eight studies were selected, and two reviewers evaluated them. Most studies were cross-sectional studies involving humans and one study was performed on rats. Our review revealed a significant correlation between periodontitis and bioaccumulation of lead and cadmium. Oxidative stress generated by trace metals, characterized by elevated levels of reactive oxygen species, causes tissue damage through lipid peroxidation, enzymatic oxidation, and stimulation of proinflammatory cytokines. In conclusion, heavy metals contamination may be a risk factor for the development of periodontitis. Oxidative stress factors seem to increase the extent of the inflammatory response.

Diatom silicon isotope ratios in Quaternary research: Where do we stand?

Silicon stable isotope ratios (expressed as δ30Si) in biogenic silica have been widely used as a proxy for past and present biogeochemical cycling in both marine and lacustrine settings, in particular for nutrient utilization reconstructions. Yet an analysis of publication trends suggests a significant decline in the application of δ30Si to Quaternary science questions in the last five years. At the same time as δ30Si proxy applications have decreased, we are learning more about its complexities: an expanding body of work is highlighting biases, caveats or complications involved in the application of δ30Si-based approaches to the sediment record. These include the demonstration of species-specific silicon isotope fractionation factors (i.e. ‘vital effects’) or the potential for Fe or other trace metals to influence silicon isotope fractionation. Others have inferred the potential of biogenic silica dissolution to alter an initial δ30Si value, or questioned the preservation of the initial δ30Si through early diagenetic processes more generally. Another challenge receiving more attention is centered around deconvolving a δ30Si-value into a signal reflecting biological productivity and a signal reflecting changes in the δ30Si of dissolved silicon driven by whole-system and/or circulation changes. Finally, a number of studies focus on analytical difficulties, especially during sample preparation related to achieving and demonstrating a contaminant free biogenic silica. These challenges lead us to posit that the Quaternary science community is moving away from silicon isotope proxies because they are losing confidence in their reliability and usefulness. Here, focusing on the diatoms – the dominant biosilicifiers in both lakes and the ocean – we synthesize progress in understanding nuances and caveats of δ30Si-based proxies in order to answer whether the fall-off in δ30Si-based Quaternary research is warranted. We suggest that with some simple steps that can be readily implemented, and with the closing of key knowledge gaps, there is no reason to believe silicon isotopes do not have a promising future in the Quaternary sciences.