Bulletin of Environmental Contamination and Toxicology最新文献

Microplastics (MPs) are tiny plastic pieces having a diameter of less than 5 mm. They can arise from larger plastic debris that degrades over time, synthetic fibres from clothing, microbeads in personal care items and even larger plastic debris. Sea cucumbers are marine creatures vital to the ocean's ecosystem as they assist in maintaining a clean seabed and recycle nutrients. The aim of this research was to characterize the types of MPs isolated from the sea cucumber Holothuria scabra from Pulau Jambongan, Sabah. A total of 30 H. scabra were collected. Their gastrointestinal tracts were removed and digested using NaOH. The digestates were filtrated several times to extract the MPs. MPs were observed under microscope and categorized into shapes and colours. To determine the functional group of polymers, further analysis using Fourier Transform-Infrared Spectroscopy (FTIR) was performed. The samples contained a total of 7403 MPs. Majority of MPs were black colored (72.25%) and in the form of fibres (99.05%). Two types of polymers were detected: polycarbonate (PC) found in 4% of the population and polymethyl methacrylate (PMMA) present in 96%. In conclusion, the presence of MPs in the gastrointestinal tract of H. scabra suggests that the animals and their habitat have been contaminated. Further study is required to comprehend the effects of MPs on sea cucumbers and other marine organisms as well as to develop prevention strategies.

The photodegradations of three selected neonicotinoid insecticides nitenpyram, thiacloprid, and acetamiprid were investigated in both water and soil samples under natural sunlight, UVA light, and UVB light. The results indicate that these insecticides undergo significant degradations when subjected to sunlight, whether they are in deionized (DI) water, tap water, and DI water containing 100 mg/L humic acids or in soil. The degradation half-lives of nitenpyram, thiacloprid, and acetamiprid in tap water under sunlight were found to be 3.7, 4.7, and 8.9 h, respectively, in DI water 5.4, 6.3, 9.1 h, respectively, in DI water containing 100 mg/L humic acids 3.6, 3.3, 6.5 h, respectively, and in soil 7.5, 7.9, and 15.9 h, respectively. The degradation due to hydrolysis was found insignificant as compared to photodegradation. The examination of the effects of light source revealed that the UVB in the sunlight plays a major role in the photodegradation of these three neonicotinoids, and the effects of UVA and visible light are negligible. The analysis on the degradation products indicated that the nitroguanidine group in these insecticides is unstable and prone to break up under sunlight. A total of nine degradation products were detected, of which the health effects and the fate and transport in the environment need to be further studied.

Microplastics (MPs) are emerging pollutants of concern in aquatic ecosystems. Fish ingest MPs accidentally during normal feeding because they resemble prey or by ingesting prey that previously consumed them. Despite severe plastic pollution in Africa, some countries, including Kenya have implemented laws to curb this pollution menace. MPs have scantly been studied in African freshwaters. This study provides empirical data and describes the levels of MPs in four commercially important fish species in Lake Victoria. A total of 95 fish samples were collected from four sampling sites (inshore-offshore waters) between March and May 2022. Microscopy and Attenuated Total Reflectance Fourier Transformed Infrared (ATR-FTIR) spectroscopy methods were used to identify MPs. In this study, 62 out of 95 (65.26%) of the gastrointestinal tracts of the sampled fish contained MPs. The four species showed different proportions of detected MPs among the sampled individuals: 75.00% (Clarias gariepinus), 75.00% (Synodontis victoriae), 71.43% (Lates niloticus), and 59.26% (Oreochromis niloticus). Polystyrene (PS) and poly (perfluorobutadiene) were the main plastic polymers in the fish samples. The condition factors estimated for O. niloticus, S. victoriae, and L. niloticus were > 1 and < 1 for C. gariepinus, respectively. Positive correlations were observed between microplastic numbers and fish length and microplastic numbers and fish weight. However, the low R² values obtained implied no strong relationship exists between these parameters. These findings provide evidence of microplastic contamination in fish in Kisumu Bay.

In this study, Vanadium (V) concentrations were analyzed in five tree species (Pinus pinaster, Cupressus arizonica, Picea orientalis, Cedrus atlantica, and Pseudotsuga menziesii) from Duzce city (Turkey), a highly polluted area. The research compared V levels across species, organs, directions, and age groups over the past 40 years. Trees, which absorb nutrients from soil and air, were used as biomonitors. Cupressus arizonica and Cedrus atlantica emerged as effective for V mitigation due to high wood accumulation. Significant inter- and intra-species variations in V concentrations were noted, underscoring their potential as V indicators. Annual rings from older trees offer a long-term monitoring method. This study highlights the importance of species-specific selection for monitoring heavy metals and the role of wood in preventing reintroduction of metals into ecosystems. It enhances our understanding of V dynamics and the environmental monitoring potential of these species.

A pot experiment at Punjab Agricultural University, Ludhiana, India, assessed rice residue biochar's effect on remediating lead and cadmium in soil and on Indian mustard growth. Soil spiked with Cd (0, 10, 25 mg kg⁻¹) and Pb (0, 25, 50 mg kg⁻¹) was amended with biochar (0, 0.5, 1, 2% w/w) in a completely randomized design with three replications. Adding 2% biochar reduced DTPA-Pb in soil and Pb in shoots by 61% and 56%, respectively. Biochar increased dry matter yield (DMY) by 18% at 1% but decreased by 19% at 2%. The 1% biochar increased shoot Fe, Mn, Zn, and Cu by 11.39%, 26.74%, 5.89%, and 17.72%, respectively. Rice residue biochar significantly improved the DMY and micronutrient content of Indian mustard by reducing lead contamination in co-contaminated soil.

Bioluminescence inhibition of Vibrio fischeri is a widely used method for toxicity testing in aquatic environments. Certain complex biological contaminants, such as lipopolysaccharide (LPS), can interfere with metabolic pathways during toxicity assays. The standard 15-minute Vibrio fischeri bioluminescence assay has limitations when evaluating and screening water toxicity against complex and emerging chemicals like LPS. To accurately determine the effects of such substances, it is crucial to use a bioassay that encompasses a sufficient cell cycle period. This study tested LPS at varying incubation times (ranging from 60 s to 60 min) and concentrations (1-1*10^- 12 mg/ml) to identify the appropriate incubation time for bioluminescence inhibition and toxicity testing. The results indicated that bioluminescence inhibition begins within 60 s and reaches maximum inhibition at 60 min. However, at 30 and 45 min, the bacterial response to different concentrations of LPS varied, with some concentrations causing increased bioluminescence. The EC₅₀ values at different times (60 s, 15, 30, 45, and 60 min) were found to be 0.0012, 0.0063, 4.07e + 54, 3.85e-8, and 3.34e-9 mg/ml respectively. This study highlights the importance of considering incubation time when using bioluminescence inhibition to detect acute toxicity in aquatic ecosystems. A longer incubation time may enhance the method's sensitivity and improve its ability to detect low levels of toxins, such as LPS, in water resources.

Triclosan (TCS), a widely used antimicrobial biocide, has raised serious concern among the scientific community in recent years owing to its ubiquitous presence around the globe and toxicity to aquatic organisms. The current study investigated the alterations in bacterial diversity, nutrients, and sediment enzyme activity in TCS-exposed sediment. TCS concentrations of 3 mg/L (T1) and 6 mg/L (T2) were applied in a microcosm setup for 28 days to sediment collected from Versova Creek, Mumbai. Among sediment enzymes, dehydrogenase activity exhibited the greatest degree of variability in 3 mg/L exposed sediment. Nitrite, total nitrogen and urease exhibited higher concentrations in 6 mg/L TCS exposed sediment. The concentration of ammonia was observed to be decreasing in treatments exposed to 6 mg/L TCS. Total heterotrophic bacteria exhibited an increase in count in T1 and a decrease in T2. Metagenomics data showed a higher relative abundance of bacteria in T1 compared to T2 on the 28th day of sampling. Proteobacteria was found to be the most abundant phylum in all samples, and their relative abundance was reduced by 0.14% in T₁ and 5.48% in T₂. The results confirm the alterations in the composition of sediment bacterial communities and their enzymatic activities due to TCS exposure.