Bulletin of Environmental Contamination and Toxicology最新文献

Ecotoxicological studies on the effects of harmful heavy metals including hexavalent chromium Cr(VI), on aquatic ecosystems have increased dramatically in recent years. Moreover, biological factors like species, age, and developmental stage are crucial in determining the ecotoxicological effects. This was the first-ever study to evaluate the acute toxicity (96 h-LC50) of Cr(VI) on Chanos chanos fry (average weight 2.5 ± 0.5 g, length 6.5 ± 1 cm) in freshwater. Seven Cr(VI) treatment groups and one control group (10 fry each) were tested for mortality, morphological, behavioural and histopathological alterations. The median lethal concentration (LC₅₀) was determined as 31.22 mg/L by probit analysis, and a safe concentration factor of 0.01 was applied to estimate the allowable safe level. This investigation provides valuable insights into the ecotoxicology and risk assessment of Cr(VI), with potential implications for culturing euryhaline fish in chromium-contaminated freshwater for species diversification.

Metals reach aquatic ecosystems through various anthropogenic activities, posing risks to aquatic life. This study investigated oxidative stress and detoxification biomarkers in Strandesia rondoniensis, an Amazonian ostracod, after 96 h of exposure to sublethal concentrations of CuSO₄, ZnCl₂, CdCl₂, and HgCl₂. Significant increases in superoxide dismutase, glutathione, and metallothionein activity were observed in response to Zn, Cd, and Hg, indicating the induction of reactive oxygen species (ROS). In contrast, copper exposure did not alter biomarker activity. Lipid peroxidation increased following exposure to Zn, Cd, and Hg, damaging cell membranes and leading to DNA damage, suggesting the antioxidant defense system was insufficient to counteract oxidative stress. The results demonstrate the sensitivity of S. rondoniensis to environmentally relevant metal concentrations, supporting its application as a neotropical model organism in ecotoxicological assessments. Furthermore, the findings underscore the need to revise Brazil's environmental legislation on permissible metal concentrations in aquatic environments.

This study evaluated the ecological capacity of Tianmu Lake and analyzed its water environment and pollution load using a distributed hydrological model (SWAT) with high spatial resolution and long time series. The findings indicated significant interannual variations in total phosphorus (TP) and total nitrogen (TN) loads, with high flow years exhibiting substantially higher levels (TP: 6.69 tons year^-1, TN: 328.85 tons year^-1) compared to low flow years (TP: 4.61 tons year^-1, TN: 210.69 tons year^-1). Monthly loads were elevated during wet and normal seasons, with spatial concentrations in the Zhongtian River basin and the Yangzhuang River basin. To achieve water quality targets for 2025, 2030, and 2035, TP and TN reductions are needed in the Shahe and Daxi Reservoirs. The study emphasizes the importance of integrated strategies, including spatial optimization, source reduction, and transport regulation, to enhance ecological capacity and mitigate pollution concentration.

The UV filter benzophenone-3 (BP-3) is a prevalent environmental pollutant due to its extensive use in personal care products, raising concerns about its ecological risks. This study investigated the pH-dependent oxidative stress effects of benzophenone-3 (BP-3) on Carassius auratus by measuring four key biomarkers-superoxide dismutase, catalase, glutathione, and malonaldehyde in liver tissue. The results demonstrated that BP-3 exposure led to significant oxidative stress, as evidenced by altered antioxidant levels and increased lipid peroxidation. The integrated biomarker response indicated that stress was more pronounced at higher BP-3 concentrations and varied with pH, being greatest under acidic conditions. These findings demonstrate that the toxicity of BP-3 is strongly influenced by environmental pH, highlighting the necessity of incorporating pH variations into ecological risk assessments of ionizable organic pollutants.

Benzophenone-3 (BP-3), a widely used ultraviolet filter in personal care products, has been extensively detected in aquatic environments and poses potential ecological risks. This study innovatively investigated the pH-dependent acute toxicity of BP-3 to three model aquatic organisms-Daphnia magna, Photobacterium phosphoreum, and Danio rerio-by determining the EC₅₀ and LC₅₀ values across a pH range of 5.0 to 9.0. Our results revealed that BP-3 exerted greater acute toxicity on all three tested aquatic organisms under acidic conditions (pH 5.0) than under alkaline conditions (pH 9.0). The increased toxicity with lower pH was attributed to the predominance of the more lipophilic molecular form of BP-3, emphasizing the significant influence of environmental pH on BP-3 toxicity. These findings provide essential toxicological data for assessing the ecological risks of BP-3 in diverse aquatic environments, highlighting the necessity of considering BP-3 concentration, environmental pH and exposed species in ecological risk assessments.

Dinoseb has been banned from use as a pesticide due to concerns about its environmental persistence and toxicity, but it is still used in the chemical industry as an inhibitor of styrene polymerization. In the present study, the potential risks of dinoseb in freshwater, sediments, and soil media in Korea were assessed based on conservative exposure scenario. Acute and chronic toxicity data for aquatic organisms were collected to derive predicted no effect concentration (PNEC_water). Due to the lack of toxicity data for sediment and soil organisms, PNEC_sediment and PNEC_soil were derived using the equilibrium partitioning method based on PNEC_water. Environmental concentrations were estimated using SimpleBox Korea model. The PNEC_water, PNEC_sediment, and PNEC_soil were 0.00145 mg/L, 0.0167 mg/kg dry weight, and 0.00242 mg/kg dry weight, respectively. PECs at regional scales were lower than PNEC, but HQ exceeded 1 at one local site. Soil samples near high-risk worksites were analyzed at two different time points to measure dinoseb concentrations. Dinoseb was found to be below the limit of quantification, indicating that, within the scope of the available data and assessment conditions, the current environmental risk of dinoseb is expected to be low, although continued monitoring is warranted.

Elevated atmospheric ammonia (NH₃) concentrations have been reported in the Athabasca Oil Sands Region of Alberta, although the source of these emissions is uncertain. We compiled monthly atmospheric NH₃ data obtained by passive samplers at 45 sites over a 4-year period and found that NH₃ concentrations were greatly elevated above background levels in the summer and were positively correlated with air temperature at sites close (< 15 km, n = 16) as well as at sites distant (> 15 km, n = 29) from the center of industrial activities. Natural surface waters in the region have not been previously considered as potential NH₃ sources even though the region is dominated by wetlands and small lakes. Measurements of 66 of these lakes showed that 30% have a pH > 8.0 with 3% having a pH > 9.0 that are expected to contain appreciable amounts of NH₃ that can be released to the atmosphere under summertime conditions. Further, most lakes are less than 3 m deep and total Kjeldahl N could be as high as 3.5 mg L^-1 in shallow lakes and the temperature of the lakes can exceed 20 °C in summer, promoting organic matter mineralization and the production of NH₄⁺. We suggest that these conditions can promote the release of NH₃ from natural waterbodies as well as tailings ponds in the summertime and explain the spatial patterns in atmospheric NH₃ that are observed regionally. These emissions need to be better characterized in further studies.