Contamination Gradient Research Articles

Structural and functional responses of soil fungal and bacterial communities to a lithium contamination gradient.

The use of lithium (Li) in decarbonization strategies has positioned it as a central component of modern technological advances, particularly in battery applications. However, the increasing demand for Li has raised concerns about its environmental consequences, which are poorly documented. This study aimed to fill this knowledge gap by examining the impact of Li on soil bacterial/fungal communities. Using a microcosm approach, we explored the impacts of increasing Li concentrations on both microbial community structure and activities. Our results revealed significant changes in bacterial/fungal communities, particularly in the bacterial communities. Most of the indicator species were negatively correlated with the Li gradient, reinforcing the harmful effect of Li. Proteobacteria dominated at low concentrations, whereas Firmicutes were the most abundant at high concentrations. OTUs affiliated with the genus Alicyclobacillus represented >29% of the total affiliated OTUs at the highest Li concentrations. Moreover, Alicyclobacillus fastidiosus showed resilience and specific adaptation to Li. Fungal communities showed less pronounced changes, with Mucoromycota remaining the dominant phylum at all concentrations. Nevertheless, some genera presented correlations with Li concentration, particularly the plant mutualists Leptodontidium, Oidiodendron, and Solicoccozyma. In addition, rapid decreases in several enzymatic activities crucial for the functioning of the carbon, nitrogen and phosphorus cycles were noted. Accordingly, microbial respiration was also impacted by high Li concentrations. Finally, a correlative analysis linked the decreases in enzyme activity to decreases in the abundances of both Proteobacteria and Ascomycota. These results underline the multiple impacts of Li on bacterial/fungal communities, highlighting both structural alterations and changes in microbial activities.

Transcriptomics highlights dose-dependent response of poplar to a phenanthrene contamination.

Polycyclic aromatic hydrocarbon (PAH) contamination in industrial soils poses significant environmental challenges, necessitating cost-effective bioremediation approaches like tree-based phytoremediation. However, the defence mechanisms and adaptability of trees to PAH exposure remain poorly understood, while the identification of molecular markers could help in the detection of toxicity symptoms. This study explores the molecular response of Populus canadensis to a phenanthrene (PHE) contamination gradient (from 100 to 2000mgkg-1) using RNA-seq analysis of roots and leaves after 4weeks of exposure. Both differentially expressed genes (DEGs) and DRomics, a dose-response tool, identified transcriptomic changes, with about 50% of deregulated genes responding significantly at a benchmark dose (i.e. minimal dose that produces a significant effect) below 400mg PHE kg-1. The highest number of DEGs was found both at a low concentration (200 and 700mgkg-1) and at the highest concentrations (1500-2000mgkg-1) for both roots and leaves. Ethylene signalling genes were activated via ABA-independent pathways at low concentrations and ABA-dependent pathways at high concentrations. Across the gradient, responses to oxidative stress were triggered, including reactive oxygen species scavenging and phenylpropanoid biosynthesis, specifically at 1500-2000mgkg-1. Additionally, PHE disrupted pathways related to plant responses to biotic stress. These findings revealed unexpected dose-dependent transcriptomic shifts, demonstrating poplar's adaptive defence mechanisms against PHE toxicity.

Arsenic modifies the microbial community assembly of soil-root habitats in Pteris vittata.

Pteris vittata, renowned for its ability to hyperaccumulate arsenic, presents a promising solution to the escalating issue of global soil arsenic contamination. This fern cultivates a unique underground microbial community to enhance its environmental adaptability. However, our understanding of the assembly process and the long-term ecological impacts of this community remains limited, hindering the development of effective soil remediation strategies. This study addresses this gap by investigating soil-root habitats from three geographically diverse fields comprising a gradient of arsenic contamination, complemented by a time-scale greenhouse experiment. Field investigations reveal that arsenic stress influences community assembly dynamics in the rhizosphere by enhancing processes of homogeneous selection. Greenhouse experiments further reveal that arsenic exposure alters the assembly trajectory of rhizosphere communities by promoting key microbial modules. Specifically, arsenic exposure increases the enrichment of a core taxon (i.e. Rhizobiaceae) in the rhizosphere, both in field and greenhouse settings, boosting their abundance from undetectable levels to 0.02% in the soil after phytoremediation. Notably, arsenic exposure also promotes a pathogenic group (i.e. Spirochaetaceae) in the rhizosphere, increasing their abundance from undetectable levels to 0.1% in the greenhouse. This raise concerns that warrant further investigation in future phytoremediation studies. Overall, this study elucidates the assembly dynamics of the soil microbiome following the introduction of a remediation plant and emphasizes the often-overlooked impacts on soil microbial community following phytoremediation. By probing the ecological impacts of remediation plants, this work advances a more nuanced understanding of the complex ecological implications inherent in phytoremediation processes.

Microplastic in bivalves of an urbanized Brazilian estuary: Human modification, population density and vegetation influence

Microplastics (MPs) global ubiquitously affects particularly coastal regions under significant anthropogenic pressures, where there are limited monitoring efforts. Bivalves are valuable sentinels of MPs contamination. This investigation determined MP contamination in oysters, clams, and mussels at Santos-São Vicente, a heavily urbanized estuary in Brazil, focusing on socio-environmental predictors, spatial distribution, and interspecies variations. Elevated MPs levels were linked to higher human modification (β = 0.5747, p = 0.0223) and reduced population density (β = −8.918e-06, p = 0.0443), regardless of vegetation cover (p > 0.05). Such a negative connection between population density and MP contamination occurred due to the significant presence of industrial and port activities, leading to high MP discharges despite a low population. The simultaneous presence of the three species at specific sites is an intrinsic limitation for broad spatial studies, depending on their environmental availability. Despite higher concentrations in clams, mussels and oysters also exhibited spatial variations in MP concentrations, serving as suitable sentinels. The central and left segments of the estuary displayed elevated MP concentrations, consistent with a well-known contamination gradient. Clams accumulated more MPs (1.97 ± 1.37 [0.00 – 5.55] particles.g−1) than mussels (0.72 ± 1.07 [0.00 – 7.74] particles.g−1) and oysters (0.70 ± 1.03 [0.00 – 7.70] particles.g−1), suggesting higher bioavailability in sediments than the water column. MPs found across all species were predominantly smaller (<1000 µm), fragments or fibers, and colorless. These discoveries lay a groundwork for prospective global investigations by linking MPs concentrations to socio-environmental predictors, contributing to the development of local mitigation measures and global discussions.

The Impact of Urban Pollution on Plasmid-Mediated Resistance Acquisition in Enterobacteria from a Tropical River.

Background: The exposure of environmental bacteria to contaminants in aquatic ecosystems accelerates the dissemination of antibiotic-resistance genes (ARGs) through horizontal gene transfer (HGT). Methods: In this study, we sampled three locations along a contamination gradient of a polluted river, focusing on isolating Enterobacteria from the surface waters to investigate the relationship between urban pollution and antibiotic resistance. The genomes of 15 isolates (5 per site) were sequenced to identify plasmid-borne ARGs and their association with resistance phenotypes. Results: Isolates from the site with the highest contamination (Site 3) showeda larger number of ARGs, plasmids, and resistance phenotypes. Notably, one of the isolates analyzed, E. coli A231-12, exhibited phenotypic resistance to seven antibiotics, presumably conferred by a single plasmid carrying 12 ARGs. Comparative analysis of this plasmid revealed its close evolutionary relationship with another IncH plasmid hosted by Salmonella enterica, underscoring its high ARG burden in the aquatic environment. Other plasmids identified in our isolates carried sul and dfrA genes, conferring resistance to trimethoprim/sulfamethoxazole, a commonly prescribed antibiotic combination in clinical settings. Conclusions: These results highlight the critical need to expand research on the link between pollution and plasmid-mediated antimicrobial resistance in aquatic ecosystems, which can act as reservoirs of ARGs.

Key active mercury methylating microorganisms and their synergistic effects on methylmercury production in paddy soils

Rice contamination with neurotoxic methylmercury (MeHg) from paddy soils is an escalating global concern. Identifying the microorganisms responsible for mercury (Hg) methylation in these soils is essential for controlling Hg contamination in the food chain and mitigating health impacts. Current research often focuses on total Hg-methylating microorganisms, overlooking the contributions of active ones, which can lead to either overestimating or neglecting the specific roles of microorganisms in Hg methylation within paddy soils. In this study, active Hg-methylating microorganisms in paddy soils were identified using a combination of DNA-SIP, Hg isotope labelling, and Hg methylation gene sequencing techniques. Our findings revealed that Geobacter and Anaerolinea are pivotal active Hg-methylating microorganisms across a contamination gradient in paddy soils. Transcriptomic analysis of soils from major rice-producing provinces in China confirmed the widespread and synergistic involvement of these microorganisms. Microbial incubation further validated their interaction significantly enhances Hg methylation, with Me198Hg concentrations increasing 2.8-fold compared to Geobacter alone and 5.2-fold compared to Anaerolinea alone. These findings enhance our understanding of microbial Hg methylation in paddy soils, providing critical insights for accurately predicting soil MeHg load, rice grain MeHg contamination, and human MeHg exposure risks.

Willow traits outperform taxonomy in predicting phytoremediation services

Phytomanagement of contaminated sites can mitigate exposure risks for surrounding populations while providing numerous ecological services. To meet these goals, trait-based models are proposed to guide plant selection. However, this relies on the assumption that plant traits can effectively predict key services and that traits of individual species can be used to predict mean, or community-level traits of a given species assemblage. To critically evaluate these assumptions, we conducted a mesocosm study where three willow species were planted in all possible combinations (1 to 3 species) in contaminated soil under a controlled environment, for 110 days. At the community-level (for every mesocosm), we measured ten functional traits and three phytoremediation services (i.e. phytoextraction, phytostabilization, and translocation factor). We evaluated the differences between observed community-level traits and expectations from traits of the corresponding species grown in monocultures. Then, we compared the predictability of phytoremediation services through species composition and community-level traits. Our results indicate that, despite the short phylogenetic gradient, willow species exhibit distinct and predictable traits within assemblages. Moreover, trait values measured here are comparable to the values retrieved on the TRY database, confirming the potential of global databases to guide trait-based efforts in phytoremediation. Phytoremediation services were not predicted by species composition (mean R2adj = 0.05), but rather well explained by community-level traits (mean R2adj = 0.52). This suggests that models incorporating functional information are better suited to predict and understand phytoremediation services. Phytoextraction was generally correlated to fast-to-intermediate aboveground growth strategies with fast-growing belowground tissues, while translocation factors were associated with slower root growth. Phytostabilization was associated with faster-growing root systems and stress-tolerant capacities from the aboveground tissues. This experiment represent a strong test for trait-based models, given the short phylogenetic and contamination gradients tested. This reinforces the potential of trait-based models in phytoremediation and phytotechnologies more broadly.

Microplastics in marine sponges (Porifera) along a highly urbanized estuarine gradient in Santos, Brazil

Microplastics (MPs) are ubiquitously found in environmental matrices, particularly affecting aquatic systems. While several marine species have been widely used to assess MP contamination, sponges (Porifera) are less used. The MPs contamination was assessed in the sun sponge (Hymeniacidon heliophila) along a gradient at the Santos Estuarine System (Brazil). A 14-fold difference between concentrations (particles g−1) was verified between the most (1.40 ± 0.81) and least (0.10 ± 0.12) contaminated sites, confirming the local contamination gradient. The MPs found were primarily polypropylene, small (1.2–1000 μm), fibrous, and colored. Considering total concentrations, sizes and shapes these spatial patterns were similar those previously detected in molluscs obtained in the same sites. On the other hand, they differed in polymeric composition and color categories. Such findings give important initial insights into the potential role of marine sponges as putative sentinels of MPs contamination.

Assessment of the viral contamination of fecal origin over a wide geographical area using an active approach with Dreissena polymorpha

Biomonitoring appears to be a key approach to assess chemical or microbiological contaminations. The freshwater mussel, Dreissena polymorpha (D. polymorpha), is a suitable tool already used to monitor chemical and, more recently, microbiological pollution. In the present study, we used this sentinel species to monitor viral contamination of fecal origin over a wide geographical distribution. An active approach was implemented based on caging of calibrated and pathogen-free organisms with the same exposure conditions, allowing spatio-temporal comparisons between different water bodies. In addition, different types of sites were selected to investigate the range of environmental concentrations that D. polymorpha are able to translate. Different viral genome targets were measured: norovirus genogroup I and II (NoV GI and GII) and F-specific RNA bacteriophages belonging to the genogroup –I and –II (FRNAPH-I and -II). Total infectious FRNAPH were also monitored.D. polymorpha was able to translate a wide range of concentrations for all the viral targets studied, meaning that this sentinel species can be used for both low and highly anthropised sites. Moreover, D. polymorpha caging proved effective in achieving gradients of viral contamination of fecal origin pressure and to highlight the contribution of tributaries to the main rivers. D. polymorpha provided spatial and temporal variations of the viral contamination. It allowed to highlight the prevalence of the FRNAPH-I and -II genogroups according to the caging site. FRNAPH-II was found to be dominant in urban areas and FRNAPH-I in rural areas. This strategy uses the caging of the sentinel species D. polymorpha on selected sites with standardised analysis methods has proven to be a promising tool for characterizing viral contamination at both large and very fine scales.

Phytoremediation of crude oil-contaminated soil using Vigna Unguiculata and associated rhizosphere bacteria

Persistent crude oil contamination poses a significant environmental challenge. In this study, the efficacy of Vigna unguiculata (L.) and associated rhizospheric microorganisms in remediating crude oil-contaminated soil within a microcosm setting was investigated. A randomized block design was employed, and soil samples were subjected to varying degrees of contamination: 0% (UR), 2.5% (CR2), 5.0% (CR5), 7.5% (CR7), and 10.0% (CR10) w/w crude oil. The investigation aimed to assess the potential of Vigna unguiculata (L.) in mitigating crude oil contamination across these defined contamination gradients. The plant growth and crude oil removal were monitored concurrently post-emergence. Plant emergence and growth were significantly affected due to contamination, especially among plants in CR5 and CR10. The bacterial population was higher in the rhizosphere, and the treatments with lower hydrocarbon contamination. It was shown that plant density encouraged the growth of bacterial communities. Significant reduction in soil TPH was observed in CR2 (76.61%) and CR7 (65.88%). There was a strong correlation between plant growth and oil-utilizing bacterial population (r2 = 0.966) and plant growth and hydrocarbon reduction (r2 = 0.956), signifying the role of plant-bacterial synergy. Saturate fractions (C30 – C32) were significantly degraded to lower molecular weight compounds (C11 – C14). Except in CR5 and CR10, the remediation within the cowpea rhizosphere was effective even at regulatory standards. Understanding the rhizosphere ecological dynamics would further highlight the role the bacteria played; hence, it is recommended.

Spatiotemporal distribution of the planktonic microbiome and antibiotic resistance genes in a typical urban river contaminated by macrolide antibiotics

The widespread application of macrolide antibiotics has caused antibiotic resistance pollution, threatening the river ecological health. In this study, five macrolide antibiotics (azithromycin, clarithromycin, roxithromycin, erythromycin, and anhydro erythromycin A) were monitored in the Zao River across three hydrological periods (April, July, and December). Simultaneously, the changes in antibiotic resistance genes (ARGs), mobile genetic elements (MGEs), and planktonic bacterial communities were determined using metagenomic sequencing. A clear pollution gradient was observed for azithromycin and roxithromycin, with the concentrations in the dry season surpassing those in other seasons. The highest concentration was observed for azithromycin (1.36 μg/L). The abundance of MLS resistance genes increased along the Zao River during the dry season, whereas the opposite trend was obtained during the wet season. A significant correlation between the levels of MLS resistance genes and macrolide antibiotics was identified during the dry season. Notably, compared with the reference site, the abundance of transposase in the effluent from wastewater treatment plants (WWTPs) was significantly elevated in both dry and wet seasons, whereas the abundance of insertion sequences (IS) and plasmids declined during the dry season. The exposure to wastewater containing macrolide antibiotics altered the diversity of planktonic bacterial communities. The bacterial host for ARGs appeared to be Pseudomonas, primarily associated with multidrug subtypes. Moreover, the ARG subtypes were highly correlated with MGEs (transposase and istA). The partial least-squares path model (PLS-PM) demonstrated a positive correlation between the abundance of MGEs and ARGs, indicating the significance of horizontal gene transfer (HGT) in the dissemination of ARGs within the Zao River. Environmental variables, such as TN and NO3−-N, were significantly correlated with the abundance of MGEs, ARGs, and bacteria. Collectively, our findings could provide insights into the shift patterns of the microbiome and ARGs across the contamination gradient of AZI and ROX in the river.

Polymetallic contamination drives indigenous microbial community assembly dominated by stochastic processes at Pb-Zn smelting sites

Indigenous microbial communities in smelting areas are crucial for maintaining fragile ecosystem functions. However, the community assembly process and their responses to polymetallic pollution are poorly understood, especially the taxa in each bin from the amplicons that contributed to the assembly process. Herein, microbial diversity, co-occurrence patterns, assembly process and the intrinsic mechanisms across contamination gradients at a typical PbZn smelting site were systematically unravelled by high-throughput sequencing. The results showed a consistent compositional profile among the indigenous communities across sampling sites, wherein genera KD4–96 from Chloroflexi and Sphingomonas from Proteobacteria emerged as the most abundant taxa. Network modularity of the high- and middle-contaminated communities at Pb and Zn smelting sites was >0.44, indicating that community populations were clustered into modules to resist high heavy metal stress. Stochastic processes dominated the community assembly, with the greatest contribution from drift (DR), which was significantly correlated with Pb, Zn, Cr and Cu contents. What's particular was that the DR-controlled bins were dominated by Proteobacteria (typical r-strategists), while the HoS-controlled bins were by Chloroflexi (typical K-strategists). Furthermore, the proportion of DR in the bins dominated by Sphingomonadaceae (phylum Proteobacteria) increased gradually with the increase of heavy metal contents. These discoveries provide essential insights for community control in restoring and mitigating soil degradation at PbZn smelting sites.

Modelling and validation of polycyclic aromatic hydrocarbons emissions from offshore oil production facilities

The development of numerical models for investigating the risks and impact caused by human activities to the marine environment is important. Herein, the recently developed ChemicalDrift Lagrangian dispersion model was coupled to a toxicokinetic model and applied to investigate emissions of polycyclic aromatic hydrocarbons (PAHs) discharged from oil and gas production facilities as produced water. The performance of the model was evaluated with available data from a monitoring survey conducted at two oil fields. The survey provided exposure concentrations by means of passive samplers and bioaccumulation data in caged mussels; multiple depths and locations were assessed. The study included 26 PAHs and alkylated derivatives, showing good agreement between the model and the survey measurements. The compounds dominating the scenario were naphthalenes and phenanthrenes. Model provided contamination gradients were in agreement with the survey results, with levels decreasing with distance away from the main sources and with higher concentrations at 20 m depth. ChemicalDrift and the toxicokinetic model provided detailed time series, showing peaks of C1-naphthalene bioaccumulation significantly higher than values accumulated at the end of the monitored period. The utilised model was able to separate the relative contributions of multiple platforms and to identify the major contamination sources, providing a valuable and versatile tool for assessing the impact of discharges at sea.

A novel approach to assess temporal baseline levels of trace metal contamination in the mussel M. galloprovincialis in the Mediterranean, Marmara and Black Seas

This study reports, for the first time, the baseline levels for fifteen trace metals in M. galloprovincialis tissue from around the Mediterranean, Marmara and Black Seas. The environmental quality in the surrounding seawater was assessed i.e., a mussel farm was investigated by using CF and DC indices, and the water quality was qualified as good for the aquacultural activities. A strong Cu-regulation in the transplanted mussels was observed and it ranged between 3.20 and 3.60 μg/g d.w. The highest bioavailability and bioconcentration of the particulate Fe fraction could present a health risk to consumers with a low risk level (1 < THQ < 9.9). Cr is considered the limiting metal for mussel consumption (< 2 kg/day). The metal contamination gradient was assessed using TEPI and TESVI indices that identified seven reference stations on the large scale and revealed that Cd is the most investigated metal in the literature databases, and found that Pb was the most bioavailable contaminant in the areas examined.

Microplastics in rocky shore mollusks of different feeding habits: An assessment of sentinel performance

Microplastics (MPs) accumulation in rocky shore organisms has limited knowledge. This study investigated MPs accumulation in filter-feeding oysters, herbivorous limpets and carnivorous snails to assess their performance as sentinel species in the MPs trophic transfer. The samples were obtained along a contamination gradient in the Santos Estuarine System, Brazil. All three studied species showed MPs concentrations related to the contamination gradient, being the oysters the species that showed the highest levels, followed by limpets and snails (average of less and most contaminated sites of 1.06–8.90, 2.28–5.69 and 0.44–2.10 MP g−1, respectively), suggesting that MPs ingestion rates are linked to feeding habits. MPs were mainly polystyrene and polyacetal. The polymer types did not vary among sites nor species. Despite minor differences in percentages and diversity of size, shape, and color classes, the analyzed species were equally able to demonstrate dominance of small, fiber, transparent, black and blue MPs. Thus, oysters, limpets, and snails are proposed as sentinels of MPs in monitoring assessments.

Soil contamination around porphyry copper mines: an example from a semi-arid climate.

Extraction and processing of disseminated metalliferous ores, porphyry copper in particular, results in significant tonnages of waste and can cause severe disturbances and contamination in natural ecosystems. This is particularly important in semi-arid climates where natural soils are often deprived of organic matter and nutrients. This study was conducted on seven sites around Sungun Copper Mine, northwest Iran. Soil texture, EC, pH, and concentrations of nutrients, organic matter, along with 16 metal and metalloids were measured in 94 soil samples. Results showed a gradient of contamination from low contamination in natural hillsides to high contamination in mine waste depositories, Waste Dump and Oxide Dump, alongside Pakhir and Sungun Rivers. Nutrient deficiency occurred in disturbed sites. The main contaminant point sources were Waste Dump, mine pit drainage, and Oxide Dump. The results of Non-metric multidimensional scaling ordination showed elevated Cd, Zn, Fe, Cu, Pb, As, Mo, Mn, Co, S concentrations, high EC, and higher sand percentage in the sites affected by mine waste and acid mine drainage. Geo-Accumulation and Potential Ecological Risk Indices indicated that Pakhir riverside, Sungun riverside, and Oxide Dump have severe to moderate levels of environmental risks. Positive correlations between certain metal elements suggest common sources and similar reaction pathways, which may contribute to their similar geochemical behaviour in transport, deposition, and interdependence. Overall, the deficiency of organic matter and nutrients along with the soil sandy texture in contaminated sites of Sungun Copper Mine are the main limiting factors in managing metal mobility and soil remediation.

Microbes and microplastics: Community shifts along an urban coastal contaminant gradient.

Plastic substrates introduced to the environment during the Anthropocene have introduced new pathways for microbial selection and dispersal. Some plastic-colonising microorganisms have adapted phenotypes for plastic degradation (selection), while the spatial transport (dispersal) potential of plastic colonisers remains controlled by polymer-specific density, hydrography and currents. Plastic-degrading enzyme abundances have recently been correlated with concentrations of plastic debris in open ocean environments, making it critical to better understand colonisation of hydrocarbon degraders with plastic degradation potential in urbanised watersheds where plastic pollution often originates. We found that microbial colonisation by reputed hydrocarbon degraders on microplastics (MPs) correlated with a spatial contaminant gradient (New York City/Long Island waterways), polymer types, temporal scales, microbial domains and putative cell activity (DNA vs. RNA). Hydrocarbon-degrading taxa enriched on polyethylene and polyvinyl chloride substrates relative to other polymers and were more commonly recovered in samples proximal to New York City. These differences in MP colonisation could indicate phenotypic adaptation processes resulting from increased exposure to urban plastic runoff as well as differences in carbon bioavailability across polymer types. Shifts in MP community potential across urban coastal contaminant gradients and polymer types improve our understanding of environmental plastic discharge impacts toward biogeochemical cycling across the global ocean.

Bioaccumulation of mercury in Lake Michigan painted turtles (Chrysemys picta).

Mercury (Hg) contamination of aquatic environments can lead to bioaccumulation in organisms, but most previous work has focused on fish and not on semi-aquatic reptiles such as turtles that traverse both terrestrial and aquatic habitats. Here, we analyzed total Hg (THg) concentrations in 30 painted turtles (Chrysemys picta) collected from Lake Michigan (USA) coastal wetlands in 2013 to determine if (1) turtles bioaccumulated THg from the environment, (2) concentrations differed between turtle liver and muscle tissue, and (3) tissue concentrations were related to environmental concentrations (e.g., sediment THg). All individual turtles had detectable THg concentrations in both liver and muscle tissue. On average, THg concentrations were over three times higher in liver tissue compared to muscle tissue. We found a positive linear relationship between muscle THg concentrations and turtle body mass, a proxy for age, suggesting bioaccumulation in this species. Neither liver nor muscle THg concentrations followed the sediment contaminant gradient in the wetlands. Despite this, location was a strong predictor of tissue concentration in a linear model suggesting that other site-specific characteristics may be important. Overall, our results demonstrate that painted turtles accumulate mercury in liver and muscle tissues at different rates, which may be constrained by local conditions. Further research is needed to better understand the relationship between environmental mercury concentrations and body burdens in animals like turtles that traverse habitats. In addition, long-lived turtles could be incorporated into pollution monitoring programs to provide a more holistic picture of food web contamination and ecosystem health.

Environmental exposure to metallic pollution impairs honey bee brain development and cognition

Laboratory studies show detrimental effects of metallic pollutants on invertebrate behaviour and cognition, even at low levels. Here we report a field study on Western honey bees exposed to metal and metalloid pollution through dusts, food and water at a historic mining site. We analysed more than 1000 bees from five apiaries along a gradient of contamination within 11 km of a former gold mine in Southern France. Bees collected close to the mine exhibited olfactory learning performances lower by 36% and heads smaller by 4%. Three-dimensional scans of bee brains showed that the olfactory centres of insects sampled close to the mine were also 4% smaller, indicating neurodevelopmental issues. Our study raises serious concerns about the health of honey bee populations in areas polluted with potentially harmful elements, particularly with arsenic, and illustrates how standard cognitive tests can be used for risk assessment.

Health and Psychological Concerns of Communities Affected by Per- and Poly-Fluoroalkyl Substances: The Case of Residents Living in the Orange Area of the Veneto Region.

Residents of an extensive area of the Veneto Region (Italy) face one of the largest technological disasters due to per- and polyfluoroalkyl substances (PFAS). On the basis of a risk gradient of contamination, the affected territories were divided into 4 areas: Red (of maximum exposure, where a human biomonitoring programme (HBM) was activated), Orange, Yellow, and Green. This article presents a case study of residents who live in the Orange Area, the second area in terms of contamination, excluded from the HBM. Semi-structured interviews were conducted with 17 residents engaged in promoting a legal procedure to exercise their right to know. Grounded theory and a thematic analysis method were used. Overall, the findings revealed that experiencing contamination causes a negative psychosocial impact on the residents' lives; difficulty accessing information; living with uncertainty, caused by the lack of institutional and health support and medical consultation; a sense of abandonment; difficulty managing preventive and protective actions; and the deterioration of relationships, on the basis of the social comparison with residents of the Red Area, to whom HBM was granted and where the concept of health ostracism has emerged. This study demonstrated that biomonitoring may help reduce discomfort in the case of contamination by informing people of their chemical exposure.