Silver nanoparticles from Tabernaemontana divaricate leaf extract: mechanism of action and bio-application for photo degradation of 4-aminopyridine

Silver nanoparticles (Ag NPs) were synthesised by the reduction of Ag⁺ to Ag⁰ in the presence of enol form of flavonoids present in plant extract of Tabernaemontana divaricate (T. divaricate). Prepared Ag NPs were characterised using UV–Vis, XRD, HR-TEM with EDX and XPS techniques. XPS spectra exhibited peaks at 366 eV and 373 eV, which specified spin orbits for Ag 3d_3/2, and Ag 3d_5/2 that confirmed the formation of Ag NPs. Ag NPs were spherical in shape with an average size of 30 nm as revealed by HR-TEM and FE-SEM techniques. EDX studies verified the high purity of Ag NPs with silver 46.96%, carbon 16.35%, oxygen 16.22%, nitrogen 20.25% and sulphur 0.21%. LC–MS analysis of plant extract confirmed the qualitative presence of alkaloids, tannins, flavonoids, phenols, and carbohydrates. Prepared Ag NPs showed good photocatalytic activity towards degradation of 4-Amniopyridine with 61% degradation efficiency at optimum conditions in 2 h of reaction time under visible light. The ten intermediates were found within the mass number of 0–450. Ag NPs synthesised using bio-extract have also shown good inactivation against Escherichia coli (E. coli) and Bacillus subtilis (B. subtilis) bacteria due to the availability of free radicals.

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Associations between Water Physicochemistry and Prymnesium parvum Presence,Abundance, and Toxicity in West Texas Reservoirs

Toxic blooms of golden alga (Prymnesium parvum) have caused substantial ecological and economic harm in freshwater and marine systems throughout the world. In North America, toxic blooms have impacted freshwater systems including large reservoirs. Management of water chemistry is one proposed option for golden alga control in these systems. The main objective of this study was to assess physicochemical characteristics of water that influence golden alga presence, abundance, and toxicity in the Upper Colorado River basin (UCR) in Texas. The UCR contains reservoirs that have experienced repeated blooms and other reservoirs where golden alga is present but has not been toxic. We quantified golden alga abundance (hemocytometer counts), ichthyotoxicity (bioassay), and water chemistry (surface grab samples) at three impacted reservoirs on the Colorado River; two reference reservoirs on the Concho River; and three sites at the confluence of these rivers. Sampling occurred monthly from January 2010 to July 2011. Impacted sites were characterized by higher specific conductance, calcium and magnesium hardness, and fluoride than reference and confluence sites. At impacted sites, golden alga abundance and toxicity were positively associated with salinity‐related variables and blooms peaked at ~10°C and generally did not occur above 20°C. Overall, these findings suggest management of land and water use to reduce hardness or salinity could produce unfavorable conditions for golden alga.     

Evaluation of uptake rate of heavy metals by Eichhornia crassipes and Hydrilla verticillata

Lakes, ponds, and streams are the sources of surface water, which anchorage the survival of aquatic life flora and fauna and maintain ecological balance. Due to urbanization, population explosion, and industrialization, these natural sources are getting polluted. Present paper is an attempt to evaluate the uptake rate of heavy metals namely lead (Pb), zinc (Zn), iron (Fe), and chromium (Cr) by the macrophytes. The two macrophytes taken for the study are Eichhornia crassipes and Hydrilla verticillata. Both macrophytes have the capacity to absorb heavy metals from contaminated water. The present experimental study was conducted to compare and identify their potential to improve the water quality by removing the heavy metals. The paper critically evaluates the water-purifying capacity of submerged macrophyte (H. verticillata) and free-floating macrophyte (E. crassipes). It also evaluates the extent up to which heavy metal can be removed by macrophyte in a given period of time.     

Sources,controls, and probabilistic health risk assessment of fluoride contamination in groundwater from a semi-arid region in Gujarat,Western India: An isotope–hydrogeochemical perspective

Environmental Geochemistry and Health - Fluoride contamination in groundwaters of a rural region in semi-arid Western India has been studied using combination of geochemical-and-isotopic...     

Cointegrated land use and CO2 emissions—the silent Columbian cattle revolution

The objective of this research is to discuss the relationship between the growth of livestock and the environmental impact it generates in Colombia. For this, data were extracted from the FAO STAT for the period of 1961 to 2017. The livestock inventory has had a significant growth during the last 50 years. This has generated environmental exposure and the release of carbon, sequestered by continuous deforestation performed in the practice of extensive livestock. Recurring to vector error correction models, we observed the existence of long-term relations between CO₂ emissions from dairy cattle and emissions from slaughtered cattle, deforestation, pastures, and forest development. Changes in CO₂ emissions from dairy cattle tend to be anticipated by changes in CO₂ emissions from the other analyzed sources, which prove how the current investment in dairy cattle results from the accumulated debates in Colombia regarding the different sources of livestock emissions.

     

Integration of pen aquaculture into ecosystem-based enhancement of small-scale fisheries in a macrophyte dominated floodplain wetland of India

Environmental Science and Pollution Research - The rapid degradation, overexploitation, and encroachment of floodplain wetlands have led to considerable decline in fish diversity and production...     

Practical ways to recycle plastic: current status and future aspects

Journal of Material Cycles and Waste Management - With sky-rocketing demand and unrestricted global production, plastics have become an inseparable part of daily human life and the circular economy...