Freshwater ecosystems are increasingly at risk from microplastic contamination. However, information on the sub-lethal toxicity of polymer-specific microplastics in freshwater fish remains limited. The current study assessed the toxicological effects of polyvinyl chloride microplastics (PVC-MPs) with a particle size range 1 to 2500 μm in juvenile Oreochromis mossambicus under controlled laboratory conditions. A 96-h median lethal concentration (LC50) of 90.2 mg/L (95% CI) was determined, and O. mossambicus were subsequently exposed to three sub-lethal concentrations (7.05, 15.63, and 40.04 mg/L) for 14 days. Following exposure, fish were euthanized to determine PVC-MPs accumulation in gill, gut, liver, and muscle. PVC-MPs accumulated in a concentration-dependent manner, with tissue-specific bioaccumulation following the order gill > gut > liver > muscle. PVC-MPs exposure significantly altered the Oxidative stress biomarkers such as superoxide dismutase (SOD), catalase (CAT), thiobarbituric acid reactive substances (TBARS), glutathione (GSH), and hepatic biomarkers, alanine aminotransferase (ALT) and alkaline phosphatase (ALP). Alteration in proximate composition (total protein, total carbohydrates and total lipids) indicated disturbance in energy metabolism. Hematological analysis revealed significant reduction in erythrocyte related indices accompanied by elevated leukocyte counts, while genotoxicity assessment showed significant increase in micronucleus frequency, demonstrating chromosomal damage. Histopathological analysis further revealed progressive epithelial lifting, hyperplasia, lamellar fusion, interlamellar cell mass alteration and erythrocyte aggregation, with lesion severity increasing with exposure concentration. Collectively, these findings demonstrate that sublethal PVC-MPs exposure induces tissue-specific bioaccumulation, oxidative stress, metabolic dysfunction, hematological alterations, genotoxicity and gill pathology in juvenile O. mossambicus, highlighting the ecological risks of PVC-MPs in freshwater ecosystems.
A comprehensive study characterizing the extensive (scattering ( σ_sca ) and absorption ( σ_abs ) coefficients) and intensive (scattering Ångström exponent (SAE), absorption Ångström exponent (AAE), and single scattering albedo (SSA)) optical properties of near-surface aerosols, was conducted at a tropical coastal site adjoining the Eastern Arabian Sea (Goa, India) for the period from December 2019 to November 2020. Temporal (seasonal/diurnal) variations in aerosol extensive and intensive properties, and the roles of continental/marine air masses (long-range transport and land–sea-breeze circulation), boundary-layer evolution, and emission patterns in modulating the aerosol population have been examined. This is the first study at a coastal site in India to probe the SAE–AAE relationship for aerosol-type classification. Distinct seasonal variability was observed in σ_sca and σ_abs , with elevated aerosol concentrations during winter and post-monsoon, attributable to the influence of continental air masses and stagnant meteorological conditions, and reduced aerosol concentrations during monsoon owing to wet scavenging and marine air intrusion. Bimodal peaks in σ_sca and σ_abs during morning (08:00–09:00 h) and evening (20:00–22:00 h) indicated diurnal variations in aerosol concentrations driven by boundary-layer evolution and anthropogenic emissions, particularly during winter. Intensive optical properties revealed a seasonal transition from fine-mode, absorbing aerosols, associated with urban pollution during winter (SAE = 1.19 ± 0.15, AAE = 1.02 ± 0.18, SSA = 0.86 ± 0.04) and post-monsoon (SAE = 1.30 ± 0.19, AAE = 0.99 ± 0.19, SSA = 0.90 ± 0.04), to coarse-mode, scattering types in monsoon (SAE = 0.40 ± 0.43, AAE = 0.94 ± 0.26, SSA = 0.93 ± 0.04). The aerosol-type classification revealed low-absorbing small particles (SPLA), black carbon-dominated (BC-dominated), large particles and BC mixture (LP/BC mix), and low-absorbing large particles (LPLA) as the dominant near-surface aerosol types across seasons. Their seasonal distributions reflected a shift from continental to marine influence, with SPLA + BC-dominated aerosol types prevalent during post-monsoon (92.2
The development of efficient photocatalysts for the removal of antibiotic and phenolic contaminants is crucial for sustainable wastewater treatment. In this study, a novel In2O3/Ag/Ag2O@AC nanocomposite was successfully synthesized via a facile green precipitation route using Cyperus rotundus rhizome extract. The structural, morphological, optical, and surface properties of the as-prepared nanocomposite were systematically characterized using XRD, FTIR, SEM–EDX, TEM, XPS, UV–visible DRS, and BET analyses. The composite exhibited excellent visible-light-driven photocatalytic performance, achieving degradation efficiencies of 95.51
Hexavalent chromium, Cr(VI), is a highly toxic heavy metal that disrupts metabolic processes and threatens aquatic ecosystems. Cyanoremediation using metabolically active cyanobacteria for heavy-metal sequestration and detoxification is a sustainable, eco-friendly remediation approach. The present study evaluated the Cr(VI) removal efficiency and physiological responses of an indigenously isolated freshwater cyanobacterium, Oscillatoria pseudogeminata, under different Cr(VI) concentrations (2, 5, 7, and 10 ppm). Growth performance, photosynthetic pigments, oxidative stress markers, antioxidant responses, and chromium uptake were assessed to determine cellular responses to metal stress. Increasing Cr(VI) concentrations caused a concentration-dependent decline in growth, biomass accumulation, and pigment content, indicating impairment of photosynthetic and metabolic processes. In contrast, oxidative stress indicators and antioxidant defense responses, including malondialdehyde accumulation, superoxide dismutase activity, and proline content, were significantly elevated at lower Cr(VI) levels (2 and 5 ppm), reflecting activation of cellular defense mechanisms. These responses declined at higher concentrations, suggesting enzyme inhibition and severe metal-induced oxidative damage. Scanning electron microscopy revealed morphological alterations in treated filaments, while atomic absorption spectroscopy confirmed significant Cr(VI) absorption by the cyanobacteria, with removal efficiencies ranging from 48 to 60%. Overall, Oscillatoria pseudogeminata demonstrates notable chromium tolerance and biosorption capacity, highlighting its remediation potential for treating chromium-contaminated water.
Endemism serves as an ecological metric and indicator, informing conservation planning worldwide. Within this context, the Western Ghats emerge as a pivotal biogeographical region, particularly renowned for its rich array of endemic species. Among the various habitats within this region, rock outcrops stand out as a critical habitat for herbaceous endemic species as they support higher endemism as compared to other habitats. Despite their ecological significance, a comprehensive understanding of the environmental factors shaping herbaceous endemic diversity within these habitats remains elusive. Understanding the effect of environmental parameters can give insights into how species would deal with current and future climate. In the present study, we studied the relationship between the distribution of herbaceous endemic species and environmental parameters. In addition to that we also investigated which microhabitats on rock outcrops support maximum endemic species. The study was conducted on 15 lateritic rock outcrops (LRO) in the Goa and Konkan regions of Maharashtra. We recorded a total of 100 herbaceous endemic taxa spanning 25 families and 48 genera. Based on Principal Component Analysis (PCA) the sites were grouped into three groups: high-elevation LROs, low-elevation Konkan LROs and low-elevation Goa LROs. NMDS revealed that this grouping is based on the elevation, annual mean temperature and isothermality. Among the various microhabitats on LROs, shallow soil covered areas emerged as pivotal microhabitats for endemic species richness followed by ephemeral flush vegetation and exposed rock surfaces. This study highlights the intricate relationship between environmental factors, microhabitat characteristics, and herbaceous endemic diversity in the Western Ghats, emphasizing that region focused studies provide crucial insights for conservation efforts.
