Archives of Environmental Contamination and Toxicology最新文献

This study presents a comprehensive depth wise assessment of metal contamination in soils surrounding oil and gas drilling sites in the Krishna–Godavari (K-G) basin, encompassing the agriculturally intensive East and West Godavari districts of Andhra Pradesh, India. These regions are characterized by fertile alluvial soils, intensive farming, and dense hydrocarbon exploration, making them particularly vulnerable to environmental degradation. Eighty soil samples were collected from ten drilling locations at multiple depths (00–20 cm, 20–30 cm, 30–60 cm, and 60–90 cm) and analysed using WD-XRF to quantify thirteen elements. Pollution levels were evaluated using multiple geochemical indices, including Geo-accumulation Index (Igeo), Enrichment Factor (EF), Contamination Factor (Cf), Modified Degree of Contamination (mCd), Nemerow Pollution Index (NPI), and Metal Pollution Index (MPI). Surface soils showed strong enrichment of Cu, Zn, Cr, and Pb, with notable migration of metals such as Ba, Ni, and Co into deeper soil horizons. This vertical transport is facilitated by factors including soil permeability, texture, irrigation practices, and seasonal monsoonal rainfall, which enhance leaching and subsurface mobility, particularly in sandy clay and alluvial soils. The results revealed significant vertical and spatial heterogeneity, with extreme contamination by Cu, Zn, and Cr observed particularly at drilling-intensive sites, indicating strong anthropogenic influence. PCA and Pearson correlation delineated both geogenic and anthropogenic associations among the elements. PMF modelling identified six distinct source profiles, including geogenic weathering, drilling muds, corrosion by-products, fertilizer application, petroleum residues, and wastewater reuse. Metals such as Cu, Pb, and Cr showed strong enrichment in surface and subsurface layers, while Ba and Sc exhibited geogenic accumulation at deeper horizons. The interactions between hydrocarbon residues and elements, along with soil physicochemical properties, were found to influence metal mobility and bioavailability. The study underscores the ecological vulnerability of hydrocarbon-rich agricultural zones to drilling-induced contamination and highlights the critical need for scientifically informed waste management, policy enforcement, and remediation planning. These findings provide a depth-resolved geochemical baseline essential for sustainable land-use practices, groundwater protection, and long-term environmental monitoring in petroleum extraction zones.

Birds serve as ecological bioindicators of metal/metalloid contamination due to their continuous environmental exposure. In northeast China, where metal/metalloid pollution is a serious environmental issue driven by anthropogenic activities, its effects on birds remain understudied. This study analyzed tail feathers from ten terrestrial raptor species across four families to assess ecological risks from cadmium (Cd), lead (Pb), arsenic (As), zinc (Zn), copper (Cu), and manganese (Mn). Results showed that Tiger Shrike (Lanius tigrinus) had the highest As (54.35 ± 69.76 mg kg⁻¹) and Cd (5.45 ± 3.94 mg kg⁻¹) residues, followed by Brown Shrike (Lanius cristatus), which also exhibited elevated Pb concentrations (33.61 ± 93.20 mg kg⁻¹). This suggests Shrikes (Laniidae) are more susceptible to metal/metalloid contamination. Significant differences in pollutant levels were found between Little Owl (Athene noctua) and Long-Eared Owl (Asio otus), despite similar feeding behaviors, indicating species-specific sensitivity. Stable carbon isotopic (δ¹³C) values suggested that predatory birds feeding in habitats with lower δ¹³C values may have greater exposure to metal/metalloid pollutants. All studied predatory bird species, except Long-Eared Owl, showed at least one metal/metalloid concentration above toxicity thresholds, highlighting potential ecological risks. These findings emphasize the need for stringent control of anthropogenic metal emissions to mitigate adverse effects on wildlife and human health.

Ingestion of lead (Pb) derived from ammunition used in the hunting of game animals is recognised as a significant potential source of Pb exposure in wild birds globally. While Pb poisoning in wild birds has been studied extensively in North America and Europe, the prevalence of Pb exposure in bird populations elsewhere, particularly in Africa, remains understudied. To address this gap in knowledge, we examined Pb concentrations in the feathers and bones of four waterfowl species (n = 37) from a region in South Africa where recreational hunting regularly occurs. Lead was detected in all feather and bone samples. While most birds had bone Pb concentrations consistent with low-level exposure (< 10 mg kg⁻¹), three individuals displayed concentrations (maximum = 63.5 mg kg⁻¹) associated with lethal Pb poisoning. Lead isotopic ratios in bone samples suggested that Pb shot was the most probable source of Pb in birds with high exposure. These findings align with recent studies on vultures, suggesting that Pb poisoning is more widespread in southern Africa than is currently recognised, affecting not only scavenging species but also waterfowl. The prevalence of elevated bone Pb concentrations compatible with lethal poisoning (8.1%) indicates that Pb exposure could have significant implications for waterfowl populations in the region. Furthermore, substantial indirect risks exist for scavenging and predatory species, as well as for humans consuming meat contaminated with Pb shot. Our findings highlight the importance of addressing the unregulated use of Pb-ammunition across southern Africa, particularly given the large hunting industry the region supports.

Soil contaminated with trivalent chromium (Cr³⁺) induced manganese (Mn) mobilization potentially leading to increased ecological toxicity. Although Cr³⁺ is relatively immobile in soil, its interaction with soil minerals indirectly increases Mn bioavailability, which poses risks to soil organisms. The objective of this study was to assess the bioavailability and potential ecological toxicity of Mn and Cr in Cr³⁺ contaminated soil using chemical extractions, earthworm (Eisenia fetida) toxicity tests, and dehydrogenase activity (DHA) as bioindicators. The mitigation of Mn toxicity in Cr contaminated soil was evaluated following amendments with biochar and calcium carbonate (CaCO₃). Both amendments increased soil pH and reduced bioavailable Mn concentrations by 44–100% through sorption and pH induced immobilization. While bioavailable Cr concentrations also decreased, the effect was less significant because Cr was originally immobile in the soil. Earthworm survival and loss in biomass was not significantly affected by biochar treatment. Dehydrogenase activity was enhanced in biochar and CaCO₃ amended soils, indicating improved microbial activity. Principal component analysis confirmed that biochar and CaCO₃ amendments reduced bioavailability and metal toxicity to levels comparable to uncontaminated soils. The assessment of bioavailability through chemical extraction and toxicity using earthworm and DHA showed similar trends in this experiment. However, high amounts of biochar may negatively affect earthworms, and a holistic approach is required to effectively evaluate amendments for mitigating metal toxicity in soils.

This study investigated ontogenetic growth changes in total mercury (THg) concentrations, δ¹³C, δ¹⁵N, and δ¹⁸O values of harbour porpoises stranded along the coast of Hokkaido, Japan, focusing on differences between males and females. Body length (BL) of the studied harbour porpoises was greater in females than in males. THg preferentially accumulated in the livers rather than in the muscles. The THg concentrations in male and female livers increased sharply and moderately when the BLs exceeded approximately 1.5 m and 1.6 m, respectively, at which BL the harbour porpoises reached sexual maturity. Significant positive correlations were found between the BL and the log Hg concentrations in the livers and muscles of both males and females. δ¹⁵N levels in muscles were higher in calves than in weaned porpoises, likely due to the consumption of ¹⁵N-enriched milk. The δ¹³C and δ¹⁵N values in immature males and females varied considerably, probably due to the variety of prey species at low THg concentrations. The δ¹³C and δ¹⁵N values in mature males and females increased with increasing BL, suggesting an increase in the trophic level of preys and a possible association with increases in the THg concentrations in their muscles and livers. A significant positive correlation was found between the BLs and the δ¹⁸O values in the muscles from both males and females. A significant correlation was also found between the log THg concentrations and the δ¹⁸O values but not with the δ¹³C values and δ¹⁵N values. These correlations suggest feeding shifts towards deep benthic waters with growth.

This study analyzed microplastics (MPs; target size: 0.1–5 mm) in freshwater fish and aquatic plants in an urban lake in Kumamoto, Japan. MPs were detected in 82% of the collected sample of herbivorous fish species, Nile tilapia (Oreochromis niloticus) and Redbelly tilapia (Tilapia zillii) at mean level of 10 ± 13 items ind⁻¹, which was more than 10 times higher than the levels found in two carnivorous fish species, largemouth bass (Micropterus salmoides) and snakehead (Channa argus). Fish samples near the outlets of stormwater runoff and a wastewater treatment plant showed higher abundances of MPs than fish collected from other locations in the lake. Polyethylene (PE), polypropylene (PP), and polyethylene terephthalate (PET) were dominant polymers in fish, accounting for 83%. These three polymers were also commonly detected in three species of aquatic plants, which retained MPs at 4.6–35 items g⁻¹ dry weight. A comparison of the characteristics of the MPs detected in the herbivorous fish and aquatic plant samples collected at the same station showed similar profiles in terms of polymer types, shape, and colors. This indicates that herbivorous fish are exposed to MPs adsorbed onto the surface of aquatic plants through their feeding activity. Our findings highlighted that aquatic plants act as a mediator to increase the bioavailability of MPs in freshwater fish by trapping MPs on the plant surface.

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This study aimed to comprehensively analyze the accumulation and distribution patterns of polycyclic aromatic hydrocarbons (PAHs) in plankton across varying exposure durations within a simulated planktonic food chain, consisting of Tetraselmis chuii (phytoplankton), Brachionus rotundiformis (rotifers), and Apocyclops sp. (copepods) cultured in a gas purging system with a continuous supply of PAHs. The investigation revealed three distinct temporal phases of PAH accumulation: before 1 h, 1–24 h, and 24–120 h. Notably, PAH concentrations exhibited substantial fluctuations during the initial two intervals but approached a steady state after 24 h of exposure. An intriguing observation was the differential accumulation of high solubility (> 1) PAHs, which were found in higher quantities in copepods compared to rotifers and phytoplankton. Conversely, low solubility (< 1) PAHs were significantly more abundant in phytoplankton, indicating potential selectivity in PAH uptake among planktonic organisms. Principal component analysis (PCA) elucidated a clear demarcation between phytoplankton and zooplankton, suggesting distinct PAH accumulation patterns influenced by trophic levels. Linear relationship was found between the bioconcentration factor (BCF) and PAH hydrophobicity (K_ow) for all PAHs within the planktonic food chain. The varying slopes in the linear regression between log BCF and log K_ow for phytoplankton, rotifers, and copepods underscored the existence of diverse pathways for PAH accumulation among planktonic organisms. This study offers valuable insights into the complex dynamics of PAH bioaccumulation, with potential implications for understanding the broader ecological impacts of PAHs.

Studies on temporal variation of metal concentrations and their relationship with metal-binding proteins in crocodilians remain scarce. This study aimed to assess interannual changes in physiological (Cu and Zn) and xenobiotic (Hg and Cd) metals, as well as metallothioneins (MTs) levels in blood plasma of 17 semicaptive Morelet’s crocodiles (Crocodylus moreletii) sampled twice (n = 34 samples) in 2016 and 2018. Metal concentrations were quantified in plasma samples, and MTs were measured as biomarkers of metal exposure. Results showed a 1.4-fold increase in Hg and 3.5-fold increase in Cd concentrations over time, possibly reflecting dietary exposure or other unmonitored environmental factors. In contrast, Cu concentrations decreased, while Zn remained stable. MTs levels did not differ significantly between years; however, linear models suggested associations between MTs and both Cu and Cd, highlighting their potential role in homeostasis and detoxification. Although based on a small sample size and limited to plasma, these findings offer insights into metal dynamics under semicaptive conditions and support the value of MTs as candidate biomarkers for future monitoring. Improved temporal frameworks and direct environmental or dietary data are needed to better interpret these trends and support conservation strategies for this endangered species.

Gadolinium (Gd) and Lanthanum (La) are rare earth elements (REEs) widely employed in contemporary technologies due to their unique physicochemical properties. However, their increasing release into aquatic environments has raised concerns about potential ecotoxicological effects. This study assessed the acute biochemical and molecular response of fourth-instar Chironomus sancticaroli larvae exposed to Gd and La at 0.03, 0.30, 3.00, and 30 μg L⁻¹. Exposure to La at 0.03 and 3.00 μg L⁻¹ induced a significant increase in acetylcholinesterase (AChE) activity, suggesting potential neurotoxic effects that may alter synaptic transmission and behavioral responses in larvae, whereas Gd did not affect AChE activity. Furthermore, La inhibited esterase-α activity, while Gd inhibited esterase-β activity in larvae exposed to 0.30, 3.00, and 30 μg L⁻¹, suggesting specific alterations in detoxification and metabolic processing pathways. Both REEs triggered oxidative stress, as evidenced by the increase in catalase and glutathione S-transferase activities at specific concentrations, which may reflect a compensatory response to increased reactive oxygen species. Lipid peroxidation was detected only at the highest La concentration (30 μg L⁻¹), indicating membrane damage and potential impairment of cellular integrity. Gene expression analysis showed downregulation of hemoglobin D across all La concentrations and hemoglobin E across all Gd concentrations, potentially compromising oxygen transport and respiratory efficiency of larvae. These sublethal alterations suggested that C. sancticaroli larvae are sensitive to both elements, with La exerting broader physiological disruption, in addition, these findings rise concern about the ecological risk of REE contamination in freshwater ecosystems.