Variations In Metal Concentrations Research Articles

Metal bioaccumulation in marine invertebrates and risk assessment in sediments from South African coastal harbours and natural rocky shores

Industrial and urban activities are major contributors to metal contamination in coastal systems, often impacting the physiology, distribution and diversity of marine invertebrates. This study assessed metal contaminations in sediments, seawater, algae and invertebrates across four armoured systems (harbours) and two natural sites along the south coast of South Africa. Bioaccumulation factors such as Biosediment (BSAF), Biowater (BWAF), Bioaccumulation (BAF) and bioremediation of metals by invertebrate bioindicators were also determined. Spatial variation in metal concentrations were observed, however, bioaccumulation of metals was site and species-specific. Invertebrates bioaccumulated higher metal concentrations in armoured than natural sites, with filter feeders exhibiting higher concentrations than grazers. Among filter feeders, Octomeris angulosa and Crassostrea gigas bioaccumulated elevated aluminium (Al), arsenic (As), chromium (Cr), zinc (Zn) and copper (Cu), while, Perna perna accumulated elevated nickel (Ni), cadmium (Cd) and lead (Pb). Among grazers, Siphonaria serrata and Scutellastra longicosta bioaccumulated elevated Al, Cr, Cd, cobalt (Co), Cu, Ni and Zn. Bioaccumulation factors indicated that (As, Ni, Zn) were bioaccumulated by algae, and invertebrates from sediment (BSAF>1) and from seawater (BWAF>1). Additionally, invertebrates bioaccumulated metals from their prey item, algae as indicated by (BAF>1). Arsenic Cd and Pb in invertebrates were above the maximum limit set for human consumption by various regulatory bodies. Our findings underscore the significant role of coastal invertebrates in bioaccumulating and bioremediating metals, suggesting a natural mechanism for water quality enhancement, especially in urbanised coastal areas.

Heavy Metals In Bivalves From Coastal Municipalities Of C apiz,P hilippines

This research study is based on the current status of heavy metal contamination in bivalves within the coastal areas of Capiz, Philippines, drawing insights from accessible data. The findings shed light on the contamination’s extent, potential threats to human health, and the pollution’s origins. The researchers acknowledge the study’s limitations. As per the findings, elevated levels of heavy metals, such as lead, mercury, cadmium, arsenic, and chromium, in bivalves collected from Capiz’s coastal regions. Variations in metal concentrations are observed among different bivalve species and sampling sites, with identified geographical distribution patterns and potential contamination hotspots. An assessment of conformity to regulatory limits and guidance for heavy metal levels in shellfish consumption is conducted, identifying any exceedances or areas of concern. The research aims to establish the extent to which bivalves from Capiz aligns with legal requirements. Potential health risks allied to the bivalve consumption are evaluated based on the detected heavy metal levels, considering various exposure routes, population characteristics, and toxicity reference values. The research scrutinizes the impact of human activities, including industrial discharges, agricultural practices, and urban runoff, on heavy metal contamination in coastal ecosystems. The ongoing discussion underscores the need for further investigation and underscores the importance of addressing the issue to ensure the environmental sustainability and safety of coastal resources in Capiz.

Bioavailability of Metals in the Biosphere

In some areas, soil, sediment, water, and organic materials may exhibit elevated concentrations of various metals. Under certain conditions, these metals can take on most bioavailable forms. To assess the impacts and potential risks associated with elevated element concentrations, understanding the fraction of whole elements in water, sediment, and soil which are bioavailable is very important. The study aims to examine these conditions to accurately assess potential environmental impacts. For the study, searches were carried out using the keywords "bioavailability", "metal" and "environment" in various combinations in English. The search was limited to articles published open access in NCBI or PubMed, Scopus, and Google Scholar. The language of the manuscript was not restricted. The complex interactions of these diverse factors highlight the difficulty of assessing and understanding the bioavailability of metals in different environmental matrices. The study identified key factors affecting the bioavailability of the metal. These factors can change over time and among different microorganisms, plants, and animals. Research involving field and laboratory studies conducted at specific locations in soil, sediment, and flora using selective chemical extraction techniques is critical to a detailed understanding of the complex ecological processes associated with the bioavailability of metals to organisms.

Seasonal variation in metals concentration associated with settled dust and their risk assessment in school children of Agra (India)

Metals associated with indoor dust are shown to be a key pollutant and resuspension of dust in critical microenvironments like schools can lead to detrimental health effects to children. The present study was carried out from December 2021 to November 2022 to examine variations in metal concentration with season and associated health risks from school dust in Agra, India. Dust samples were digested in aqua-regia followed by analysis for metals concentration by ICP-AES. Geo-accumulation (Igeo), pollution (PI), integrated pollution (IPI), and pollution load (PLI) indexes were used to determine metals contamination, Principal Component Analysis and Cluster Analysis were employed for the identification of causative sources of metals while USEPA health risk assessment models were utilized to assess the health risks in children. The results indicated that in all seasons settled dust of roadside schools of both regions accumulated higher concentrations of metals as compared to residential schools except semi-urban schools in post-monsoon season. The total metal concentration (mgkg−1) in school dust samples of Agra ranged from 62507–85037, 72477–97022, 48912–66083 to 58605–92290 in winter, summer, monsoon, and post-monsoon respectively. In all seasons, the PLI values of settled dust of all schools ranged from less than one to greater than unity which indicates pollution levels by metals. Further, Igeo values revealed that school dusts were moderately and heavily contaminated by Cd in all seasons. The assessment of health risk specifies ingestion as the main exposure route followed by dermal intake and inhalation. The Hazard Index value for all examined metals was lower than the safer limit of one while on the contrary for Pb, total cancer risk was higher the than safer limit via inhalation pathway. The findings of the study indicate that more investigations are required on potentially toxic metal contaminations in schools of Agra, especially for Pb, Cd and Cr.

Efficiency of Portable X-ray Fluorescence for Distinguishing Lead Slag.

In the Minier Valley (France, Aveyron), an archaeological site excavation has led to the discovery of 25 kg of lead (Pb) slag, found in a secondary position. On a macroscopic level, these slags can be classified into two distinct categories, vitreous black and porous gray. This clear visual differentiation has been previously documented at other Pb-silver (Ag) metallurgy sites dating from the 12th century to the 14th century in Europe, and more particularly in the workshops of Mont Lozère, located approximately 80 km away from Le Minier. However, to date, scant evidence exists regarding the specific metallurgical process that produced this slag. This study presents the results of the analysis of 218 Pb slags (Supplemental Material) using portable X-ray fluorescence (pXRF). This method does not appear to be ideally suited for investigating this type of artifact, as it does not provide quantification of oxygen content. Nevertheless, it can be used to quickly identify trends and determine whether the two identified facies exhibit dissimilar chemical compositions. The results indicate that, based on the elemental compositions of the slags, no discernible distinction can be made to categorize them into two separate groups, both in bivariate and multivariate analyses. Consequently, it can be inferred that the gray and black slags originate from a single process executed within the same type of furnace. Scanning electron microscopy energy dispersive spectrometry analyses on selected samples demonstrate that variations in metal content are considerably exaggerated by pXRF, but that the trends observed are confirmed. The use of pXRF is therefore a relevant tool for determining whether or not Pb-Ag slag is the result of the same process. However, this initial approach needs to be refined by other analyses to confirm whether the smelted ores are of local origin and to be able to better define the details of the metallurgical process used.

A Comparative Analysis of Sparisoma cretense in Island Environments: Unraveling Metal Accumulation Differences in the Canary Islands (Spain, NW African Waters).

This study investigates the impact of varying environmental conditions on the metal composition within the tissues of Sparisoma cretense, contributing to the understanding necessary to offer scientifically sound advice regarding the health status of this species. This knowledge extends beyond fishery production, encompassing implications for food security. The data span the years 2022 and 2023, encompassing both cold and warm climatic seasons. The concentrations of various metals, such as Al, Zn, Cd, Pb, Fe, and Cu, exhibited noteworthy variations across the islands, with significant increases recorded in 2023, particularly during the warm season. The intricate interplay between multiple factors shaped the availability of the analyzed elements in S. cretense. Factors such as rising temperatures during the warm season increased biological activity in marine ecosystems, seasonal fluctuations in weather conditions, water quality, and anthropogenic influences, all contributing to the observed variations in metal concentrations. Additionally, the geological composition of each island and the patterns of marine currents and sediment transport play pivotal roles in these differences. Comprehensive scientific research, monitoring, and environmental surveillance are essential for a holistic understanding of this variability and providing valuable insights for the conservation and management of marine ecosystems in the Canary archipelago.

Assessment of toxic trace elements (Cd, Pb, As, and Co) in small, medium, and large individuals of Mytilus galloprovincialis and Perna perna mussel species along the Algerian coast.

This research paper focused on the monitoring of marine sites using mussels, which are highly valuable organisms in assessing environmental health. However, a significant challenge arises when determining the appropriate size of mussels for monitoring purposes. The objective of this study was to examine the levels of Cd, Pb, As, and Co in three different size classes of two mussel species, Mytilus galloprovincialis and Perna perna, collected from three sites along the Algerian coast, each exhibiting varying degrees of pollution.At each of the study sites, a total of thirty individuals from small, medium, and large size classes of mussels were collected during four different time periods. The mussels were then dissected, and the concentrations of Cd, Pb, As, and Co were measured in the entire flesh of the mussels using ICP-MS.Across the various study sites, the concentrations of cadmium, lead, arsenic, and cobalt ranged from 0.06 to 1.32mg/kg, 0.09 to 12.56mg/kg, 4.23 to 18.31mg/kg, and 0.11 to 1.85mg/kg, respectively. Interestingly, the distribution of these metals in the three different size classes of mussels followed a consistent pattern at all the study sites. Large mussels exhibited higher concentrations, while small and medium-sized mussels displayed lower levels. These findings highlight substantial spatial and temporal variations in metal concentrations within the studied sites.

Abiotic and biotic factors influencing heavy metals pollution in fisheries of the Western Amazon

The escalating industrial and artisanal extraction of natural resources in the Amazon Basin has centered it into the spotlight of global environmental concern. This study deals with the environmental problems of heavy metals pollution and biomagnification, which stem from mining, agricultural, petrochemical, and industrial discharges. We conducted an extensive investigation, analyzing 360 fish specimens representing 58 species, to assess the concentrations of 11 metals (Al, As, Cd, Cr, Cu, He, Mn, Ni, Pb, Zn, and Hg) along the Ecuadorian sections of the Napo and Pastaza watersheds. Stable isotope analyses (δ15N and δ13C) were employed to determine their trophic positions and potential biomagnification risks. Sampling was carried out during two distinct hydrological seasons to capture seasonal variations in metal concentrations. Furthermore, we estimated species-specific daily heavy metal intake levels. The results of our study revealed that 15 fish species and 53 individual specimens exhibited heavy metal concentrations surpassing recommended standards, with elevated levels of Al, As, and Hg posing significant risks to human consumers with daily intakes of 0.46 kg/day. Notably, our investigation unveiled concerning trends, including increased metal concentrations, Hg biomagnification within fish populations from the Pastaza watershed, and an association between smaller fish size and higher metal content. This study provides a crucial baseline for monitoring future environmental changes and understanding the persistent impacts of heavy metal pollution in the Ecuadorian Amazon region and the broader Western Amazon. It underscores the urgent need for sustainable environmental management practices to mitigate the escalating threat to these vital ecosystems.

Impact of the lockdown period during the COVID-19 pandemic on the metal content of the anemone Anemonia sulcata in the Canary Islands (CE Atlantic, Spain)

Anemones, specifically the species Anemonia sulcata, are cnidarians that serve as bioindicators in marine ecosystems, indicating the health of the environment and changes in environmental conditions. Monitoring anemone populations and studying their well-being and distribution provide valuable insights into marine ecosystem conditions. This study aimed to investigate the impact of the SARS-CoV-2 pandemic on the metal content of Anemonia sulcata. Over a six-year period (2017–2022), twenty specimens of Anemonia sulcata were collected in Tenerife, Spain. The results showed that in 2020, during the two-month lockdown in Spain from March to May when tourism was halted, A. sulcata exhibited the lowest concentrations of various metals studied (Al, Cd, Cu, Fe, Pb, and Zn). This finding suggests that the reduced anthropogenic pressure on the coast due to the absence of tourism significantly decreased pollution levels. Therefore, the study emphasizes the importance of promoting sustainable tourism worldwide. The research highlights that minimizing human impact on coastal areas through responsible tourism practices can effectively reduce pollution in marine ecosystems.

Heavy metal concentrations in Canada geese, snow geese, mallards, and American coots from the northern Rocky Mountains in Montana

AbstractThe presence of metals in migratory bird tissues is well established and mining as an anthropogenic source of exposure to metals is well reported in the scientific literature. Determining the difference between what are hypothesized as normal metal levels and those associated with acute mining toxicity is challenging as spatial and temporal overlap of migratory birds with anthropogenic point sources can be highly variable at individual, population, and species levels. We examined the concentrations of 5 geologically prominent metals and metalloids in the region (arsenic, cadmium, copper, manganese, and zinc) in tissues (kidney, n = 64; liver, n = 65; and muscle, n = 65) from 4 species common to the northern Rocky Mountains in western Montana (Canada goose, Branta canadensis, n = 12; snow goose, Anser caerulescens, n = 15; mallard, Anas platyrhynchos, n = 32; and American coot, Fulica americana, n = 6), to identify metal concentrations for comparison to acute mining‐associated mortalities. Metal levels were highly variable across tissue types for all species. For example, the highest concentrations of copper, manganese, and zinc were measured in the liver (18,300, 3,960, and 38,200, respectively; ug/kg), while cadmium levels were highest in the kidney (973 ug/kg). Among species and tissue types, metal levels were also highly variable. For example, copper levels in mallards were highest in the kidney (6,700 ug/kg) and lowest in muscle (2,780 ug/kg). In contrast, copper levels in American coots were highest in muscle (14,400 ug/kg) and lowest in the kidney (5,060 ug/kg). While the wide variation in metal concentrations among species and tissue types measured in our study can make for difficult comparisons, the results are similar to control cases from other peer‐reviewed publications, and several times lower than dose‐response experiments and incidents in which mining‐associated mortality was known. Our results provide metal concentrations in migratory bird species that utilize the northern Rocky Mountains through Montana, which are essential data for assessing exposure, risk, and mortality associated with anthropogenic activities in the region.

Metal and metalloid bioaccumulation in dried red seaweed Hypnea musciformis and health risk assessment for consumers

This study measured 22 metal and metalloid concentrations in Hypnea musciformis from the Bakkhali River estuary and Saint Martin's Island, Bangladesh and determined their potential impact on consumption. Student t-tests showed a significant variation in metal concentrations between the two sampling sites (p < 0.05). Mean concentrations of Co (2.49 ± 0.05 mg/kg), Fe (793.29 ± 11.76 mg/kg), Mn (368.72 ± 4.87 mg/kg), Pb (3.82 ± 0.02 mg/kg), V (11.23 ± 0.20 mg/kg) and Zn (16.60 ± 0.28 mg/kg) were higher in samples collected from the Bakkhali River estuary compared to Saint Martin's Island, while mean concentrations of Ca (484.18 ± 4.68 mg/kg), Cd (2.44 ± 0.03 mg/kg), Mg (2112.70 ± 17.80 mg/kg), Mo (1.57 ± 0.06 mg/kg), Sr (2377.57 ± 29.98 mg/kg), and Ti (258.27 ± 4.62 mg/kg) were higher in samples collected from Saint Martin's Island. Eight heavy metals (Pb, Cd, Zn, Cu, Ni, Mn, Cr, Fe) were used to assess potential health risks for adults, but no potential health risk was detected (HQ value>1). This study reveals positive Se-HBV for H. musciformis collected from both sampling sites, indicating no potential risks involved with Hg toxicity.

Modeling the Genetic Components of the Water and Chemical Runoff of Heavy Metals in the Basin of the Nizhnekamskoe Reservoir

A semi-distributed physical-mathematical model ECOMAG-HM is used to simulate the genetic structure of water and chemical runoff of copper, zinc, and manganese in a large river basin of the Nizhnekamsk Reservoir. The model was tested against long-term data of hydrological and hydrochemical monitoring of water bodies. The contributions of the surface, soil, and subsoil components of the water and chemical runoff of metals are estimated for different segments of river network. It was found that, in the major portion of the catchment, river pollution by metals is mostly due to their diffuse washout from the soil layer. The effect of the genetic structure of water and chemical runoff on the year-to-year and seasonal variations of metal concentrations in the river network is demonstrated.

Spatiotemporal distribution and pollution assessment of trace metals in the Buriganga River, Bangladesh.

The Buriganga River plays a key role in the socioeconomic structure of Dhaka, the capital of Bangladesh. However, this river is severely polluted and is considered one of the most polluted in the world. Therefore, this study aimed to assess the concentrations of various metals in the Buriganga River. A study was conducted from August 2019 to February 2020 to determine the concentrations of 16 metals in water samples (n = 210) collected from 10 distinct sites in the Buriganga River. The mean values for the concentrations of Cr, Mn, Ni, Zn, As, Se, Cd, Sb, and Pb in river water were above the guideline values prescribed by the WHO, Japan, and Bangladesh. Moreover, the fraction ratios of Be, Cr, Co, Ni, Cu, Zn, Se, Mo, Ag, Cd, Sb, and Pb were high (>0.85); consequently, these metals could accumulate at high concentrations in river sediments. Assessment using the single-factor pollution index allowed the classification of the pollution level as 'serious pollution' for Sb and 'heavy pollution' for Cd, Ni, and Pb. The trace metal concentrations in this river imply that crops cultivated along the river using river water may also be contaminated with trace metals.

Long-Term Changes in the Pollution of Warta River Bottom Sediments with Heavy Metals, Poland-Case Study.

Variability in the heavy metal concentrations in aquatic environments may be influenced by a number of factors that may occur naturally or due to anthropopressure. This article presents the risk of contaminating Warta River bottom sediments with heavy metals such as As, Cd, Co, Cr, Cu, Hg, Mn, Ni, Pb, and Zn. Samples collected from 35 sites located along the river course were analysed over the period of 2010-2021. The calculated pollution indices are characterised by significant spatial variability that was additionally subject to changes in subsequent years. The analysis may have also been influenced by individual measurement results that, in extreme cases, may strongly deviate from the concentration values determined in the same site during the remaining years. The highest median concentrations of Cd, Cr, Cu, Hg, and Pb were in samples collected from sites that are surrounded by areas of anthropogenic land use. Samples from adjacent sites to agricultural areas showed the highest median concentrations of Co, Mn, and Ni, and Zn for those adjacent to forest areas. The research results indicate that, when analysing the degree of the risk of contaminating river bottom sediments with heavy metals, it is necessary to take into account long-term variability in metal concentrations. Taking into consideration data from only one year may lead to inappropriate conclusions and hinder planning protective measures.

Heavy Metals in Post-Exploitation Reservoirs—The Bagry Lake Case Study (Poland)

The paper presents the research study on the concentration of Fe, Mn, Cu, Pb, Zn, Cd and Ca in the sediment as well as in the supernatant (layer of water just above the sediment) of the Bagry Lake, Cracow (Poland); Ca was not included in the supernatant analysis. There are a number of works in the literature on the concentrations of metals in the water environment of flow-through dam reservoirs and factors influencing their distribution. These reservoirs were created for various purposes, e.g., water supply, flood protection, leveling the flows in the rivers and recreational purposes. Since it is difficult to find information on metals and factors influencing their distribution in the aquatic environment of post-exploitation reservoirs, this work aims to fill this gap. The additional purpose of the work was to assess the potential influence of metals’ presence in the sediment of Bagry Lake on benthic organisms. Correlations between metals in the sediment and their volatile and mineral fractions as well as in particle size fractions of ≥0.06 mm and &lt;0.06 mm were determined. Except for cadmium, metals showed a positive correlation with the sediment volatile fraction of granulometry &lt;0.06 mm (a clay-silty fraction). It has been shown that metals, in both supernatant and sediment, are of an anthropogenic origin related to previous on-lake operations, as well as a nearby modern technical infrastructure. Statistical models were used to measure the strength of relationships between the concentration of various metals in the sediments. A cluster analysis was used to study interactions between the concentration of metals in supernatant, in sediment and in its volatile and mineral fractions as well as in fractions with different granulation. It was found that individual metals and sediment fractions form pairs of quite strong clusters, e.g., Fe sediments and Mn sediments, Fe supernatant and Mn supernatant, Cu supernatant and Pb supernatant, volatile fraction and mass fraction of particles &lt; 0.06 mm and mineral fraction and mass fraction of particles ≥ 0.06 mm. The equilibrium model “supernatant—sediment mineral fraction—sediment volatile fraction” was developed for metals in various granulometric fractions of the sediment as well as in the supernatant. The model estimated a metal concentration in both fractions of the sediment (separately) as well as an impact they had on the metal concentration in the supernatant. It also showed how changes in a metal’s concentration in both fractions are reflected in concentrations of metals in the aquatic environment.

Investigation on metal geochemical cycling in an anthropogenically impacted tidal river in Belgium

The geochemical behavior of metals in water and sediment was investigated in the tidal section of the Zenne River in Belgium. Twelve-hour sampling campaigns were performed in October 2013 and March 2021 at the mouth of the Zenne River, under dry and rainy weather conditions respectively. Water samples were collected every hour while the passive samplers of Diffusive Gradients in Thin-films (DGT) were deployed continuously during a tidal cycle. In addition, bottom sediments were sampled at the tidal station and water samples were taken upstream and downstream of that station to identify the metal sources. The highest concentrations of Fe, Mn, Pb, Cr, Ni and Zn appear at low tide, indicating the Zenner River as a main source. However, for Co, Cd and Cu, other sources including upstream transport may explain their behavior during a tidal cycle. Fe, Pb and Cr are essentially transported in the particulate phase (<10 % dissolved) while the other metals in the dissolved phase (20 to 90 %). Rainfall and wind gust events also play an important role in trace metal distribution, increasing sediment resuspension and metal desorption. A good agreement was found between the time-averaged dissolved and DGT-labile metal concentrations with the exception of Cu and Fe, which form strong organic Cu complexes and Fe colloids respectively. The sediments of the tidal Zenne are contaminated by trace metals, thus acting as a secondary pollution source to the river. The reductive dissolution of Mn and Fe oxyhydroxides and the release of associated trace metals are the main mobilization mechanisms. Knowledge of the upstream and downstream levels in the water column, the benthic fluxes, which are based on turbulent diffusion, and the partitioning between dissolved and particulate phases allow to explain the metal concentration variations during the tidal cycle.

Intra- and inter-annual variations in metal concentrations in the superficial water of a highly polluted urban basin of Argentina.

To protect ecosystems impacted by human activities and prevent their degradation, it is imperative to evaluate variations in the concentration of environmental pollutants over time. Here, we evaluated the intra- and inter-annual variations of several metals from 15 sites in the Matanza Riachuelo River basin (one of the most polluted in the world) and determined the physicochemical and meteorological parameters associated with these changes from 2008 to 2015. For this, in each site, we used Asymmetric Eigenvector Maps and Redundancy Analysis. The results highlighted temporal patterns of metal concentrations and several factors associated with them, perhaps related to the actions performed in the area since 2008. Additionally, we found that the effects of physicochemical and meteorological factors on metal concentrations were site-dependent, possibly related to the presence of different local sources of pollution or characteristics of the river in each site, such as its sediments. This approach could be applied to different scenarios (aquatic and terrestrial) and could provide a tool to help decision-makers address the harmful consequences of the continuous advance of human activities on human and ecosystem health.

Prenatal Environmental Stressors and DNA Methylation Levels in Placenta and Peripheral Tissues of Mothers and Neonates Evaluated by Applying Artificial Neural Networks.

Exposure to environmental stressors during pregnancy plays an important role in influencing subsequent susceptibility to certain chronic diseases through the modulation of epigenetic mechanisms, including DNA methylation. Our aim was to explore the connections between environmental exposures during gestation with DNA methylation of placental cells, maternal and neonatal buccal cells by applying artificial neural networks (ANNs). A total of 28 mother-infant pairs were enrolled. Data on gestational exposure to adverse environmental factors and on mother health status were collected through the administration of a questionnaire. DNA methylation analyses at both gene-specific and global level were analyzed in placentas, maternal and neonatal buccal cells. In the placenta, the concentrations of various metals and dioxins were also analyzed. Analysis of ANNs revealed that suboptimal birth weight is associated with placental H19 methylation, maternal stress during pregnancy with methylation levels of NR3C1 and BDNF in placentas and mother's buccal DNA, respectively, and exposure to air pollutants with maternal MGMT methylation. Associations were also observed between placental concentrations of lead, chromium, cadmium and mercury with methylation levels of OXTR in placentas, HSD11B2 in maternal buccal cells and placentas, MECP2 in neonatal buccal cells, and MTHFR in maternal buccal cells. Furthermore, dioxin concentrations were associated with placental RELN, neonatal HSD11B2 and maternal H19 gene methylation levels. Current results suggest that exposure of pregnant women to environmental stressors during pregnancy could induce aberrant methylation levels in genes linked to several pathways important for embryogenesis in both the placenta, potentially affecting foetal development, and in the peripheral tissues of mothers and infants, potentially providing peripheral biomarkers of environmental exposure.

Variation in metal concentration across tree organs and stands: implications for reference specimen development

Air pollution is a major environmental and public health issue in urban areas. Biomonitoring using trees has been widely used to determine atmospheric pollution due to its advantages of low cost, high spatial distribution, and accumulation of a wide range of air contaminants. However, challenges exist in applying the data obtained from biomonitoring trees, including differences in pollutant concentrations in samples of the same species from different locations, and the influence of biological and environmental parameters on metal accumulation. This study aims to inform the design of biomonitoring sampling for urban air quality studies and increase their applications to exposure assessment. Specifically, the study evaluates the variation in metal concentration in tree organs of two regionally relevant tree species (Picea pungens and Populus Alba), explores the implications of different aspects of field sampling, such as variation within tree stands, tree age, and develops a reference specimen to establish threshold values for differentiating between background levels and increased exposure. The results provide insight into the complexity of using biomonitoring trees for exposure assessment and the importance of considering multiple factors in study design.

Effect of metal pollution on the distribution and co-occurrence pattern of bacterial, archaeal and fungal communities throughout the soil profiles

Metal pollution has raised negative impact on microbes, but little is known about the distribution and co-occurrence pattern of bacterial, fungal and archaeal communities along the soil profiles at multiple metal contamination sites. Here, we characterized the variations of metal concentrations and microbial communities with soil depth along five deep bores at the Tanghe Sewage Reservoir, a typical metal contamination area on the North China Plain. Co, Cd, Mg, Se, and Li were identified as the major contaminants in this area, and the pollution load index was 1.88, 1.54 and 1.62 in the shallow layer (0–0.6 m), deep layer (>2.0 m) and middle layer (0.6–2.0 m), respectively. The diversities and compositions of bacterial, archaeal and fungal communities varied significantly along the soil profiles. Deterministic process played a crucial role in shaping the difference of microbial community compositions among different soil layers, in which metal levels contributed more than soil physiochemical parameters. Furthermore, the interspecific co-occurrence network was most complex in the middle layer, indicating that metal pollution could decrease microbial network complexity. Bacterial keystone species in the co-occurrence networks showed both positive and negative correlations with polluted metals, whereas most archaeal and fungal keystone species were negatively related to multiple metals. These findings increased our understanding of distribution patterns, co-occurrence networks and environmental drivers of microbial communities in metal pollution soils.