Preparation and Characterization of Gamma Irradiated Sugar Containing Starch/Poly (Vinyl Alcohol)-Based Blend Films

Blends based on different ratios of starch (35–20%) and plasticizer (sugar; 0–15%) keeping the amount of poly(vinyl alcohol) (PVA) constant, were prepared in the form of thin films by casting solutions. The effects of gamma-irradiation on thermal, mechanical, and morphological properties were investigated. The studies of mechanical properties showed improved tensile strength (TS) (9.61 MPa) and elongation at break (EB) (409%) of the starch-PVA-sugar blend film containing 10% sugar. The mechanical testing of the irradiated film (irradiated at 200 Krad radiation dose) showed higher TS but lower EB than that of the non-radiated film. FTIR spectroscopy studies supported the molecular interactions among starch, PVA, and sugar in the blend films, that was improved by irradiation. Thermal properties of the film were also improved due to irradiation and confirmed by thermo-mechanical analysis (TMA), differential thermo-gravimetric analysis (DTG), differential thermal analysis (DTA), and thermo-gravimetric analysis (TGA). Surface of the films were examined by scanning electron microscope (SEM) image that supported the evidence of crosslinking obtained after gamma irradiation on the film. The water up-take and degradation test in soil of the film were also evaluated. In this study, sugar acted as a good plasticizing agent in starch/PVA blend films, which was significantly improved by gamma radiation and the prepared starch-PVA-sugar blend film could be used as biodegradable packaging materials.     

Hidden demographic impacts of fishing and environmental drivers of fecundity in a sea turtle population

Fisheries bycatch is a critical threat to sea turtle populations worldwide, particularly because turtles are vulnerable to multiple gear types. The Canary Current is an intensely fished region, yet there has been no demographic assessment integrating bycatch and population management information of the globally significant Cabo Verde loggerhead turtle (Caretta caretta) population. Using Boa Vista island (Eastern Cabo Verde) subpopulation data from capture–recapture and nest monitoring (2013–2019), we evaluated population viability and estimated regional bycatch rates (2016–2020) in longline, trawl, purse-seine, and artisanal fisheries. We further evaluated current nesting trends in the context of bycatch estimates, existing hatchery conservation measures, and environmental (net primary productivity) variability in turtle foraging grounds. We projected that current bycatch mortality rates would lead to the near extinction of the Boa Vista subpopulation. Bycatch reduction in longline fisheries and all fisheries combined would increase finite population growth rate by 1.76% and 1.95%, respectively. Hatchery conservation increased hatchling production and reduced extinction risk, but alone it could not achieve population growth. Short-term increases in nest counts (2013–2021), putatively driven by temporary increases in net primary productivity, may be masking ongoing long-term population declines. When fecundity was linked to net primary productivity, our hindcast models simultaneously predicted these opposing long-term and short-term trends. Consequently, our results showed conservation management must diversify from land-based management. The masking effect we found has broad-reaching implications for monitoring sea turtle populations worldwide, demonstrating the importance of directly estimating adult survival and that nest counts might inadequately reflect underlying population trends.     

Green construction for low-carbon cities: a review

Environmental Chemistry Letters - The construction industry is a major user of non-renewable energy and contributor to emission of greenhouse gases, thus requiring to achieve net-zero carbon...     

Strategies to save energy in the context of the energy crisis: a review

Environmental Chemistry Letters - New technologies, systems, societal organization and policies for energy saving are urgently needed in the context of accelerated climate change, the Ukraine...     

Optimizing hydrogen production by alkaline water decomposition with transition metal-based electrocatalysts

Burning fossil fuels account for over 75% of global greenhouse gas emissions and over 90% of carbon dioxide emissions, calling for alternative fuels such as hydrogen. Since the hydrogen demand could reach 120 million tons in 2024, efficient and large-scale production methods are required. Here we review electrocatalytic water splitting with a focus on reaction mechanisms, transition metal catalysts, and optimization strategies. We discuss mechanisms of water decomposition and hydrogen evolution. Transition metal catalysts include alloys, sulfides, carbides, nitrides, phosphides, selenides, oxides, hydroxides, and metal-organic frameworks. The reaction can be optimized by modifying the nanostructure or the electronic structure. We observe that transition metal-based electrocatalysts are excellent catalysts due to their abundant sources, low cost, and controllable electronic structures. Concerning optimization, fluorine anion doping at 1 mol/L potassium hydroxide yields an overpotential of 38 mV at a current density of 10 mA/cm². The electrocatalytic efficiency can also be enhanced by adding metal atoms to the nickel sulfide framework.

     

Planting trees to combat global warming

Environmental Chemistry Letters -     

Impact of mining industries on the groundwater level fluctuation in Singrauli coalfield area by using remote sensing and GIS,India

The coal mining industries influence hydro-geological parameters, which affect the aquifer recharge in the coal mining areas. This research aimed to evaluate the impact of various hydro-geological parameters on fluctuation of groundwater level in the study area. The various hydro-geological parameters such as soil, geology, drainage pattern, elevation and slope have been considered to accomplish the objective. A comparative analysis was performed by comparing the groundwater level fluctuation (WLF) map with the GIS-based various hydro-geological parameter maps to assess the combined influence of different hydro-geological parameters on groundwater level fluctuation. A total of eighty-six (86) dug-wells were chosen to monitor the level of the groundwater for around ten blocks of Singrauli coalfield, and these wells were examined during the months of dry and wet seasons for 2016. Based on the comparative analysis between the WLF map and thematic maps of various hydro-geological parameters, it has been found that WLF in the south-western and some portions of the north-eastern showed moderate to a higher value. This may be because most of the non-hilly areas come under gentle to moderate slope category, with lower elevation in the area forming the suitable hydro-geological condition for recharging groundwater. It was observed that the northwest, south-east and central part of the study area showed lower WLF, which may be due to the presence of overburden dump, presence of higher elevation and steep slope. Thus, the combined effect of slope, elevation, geology, drainage and mining activities on the WLF in the study region is moderate.     

Exfoliation and Decoration of Graphene Sheets with Silver Nanoparticles and Their Antibacterial Properties

High quality graphene sheets (GRP) have been exfoliated using facile one pot method through direct ultrasonication of graphite in the presence of polyvinyl alcohol. The GRP were decorated with silver nanoparticles (AgNPs) producing graphene–silver nanoparticle composites. The effect of variation of graphite and silver salt mass ratios on the morphology and performance of produced composites was studied. The size of AgNPs decorated on GRP has been tuned with synthesis method optimization. The average size of AgNPs was found to be in the range of 8.6–15.6 nm. Cotton–polyester blend textile fabrics were treated with the new smart developed composite as antibacterial agent producing new composites. A significant inhibition of bacterial growth has been observed for graphene–silver nanoparticle composite and the antibacterial efficiency was optimized. The clear inhibition zone for textiles treated with new developed composite and AgNPs alone was recorded as 12 and 1.75 mm respectively, achieving more than six fold improvement.     

Appraisal of the groundwater balance components from multi-remote sensing datasets in a semi-arid region

Semi-arid regions across the globe are fronting water crises, signaling a challenge to ensure future water security. Given the high inter-seasonal rainfall variability and unrestrained groundwater extraction, the precise quantification of groundwater flow components in an aquifer system is a priority. To address this challenge, we used high-resolution remote sensing (RS) data (Landsat and IRS) and GIS modeling (SEBAL, ArcCN) to spatially quantify major groundwater balance (GWB) components, viz., evapotranspiration (ET), rainfall recharge (R), surface runoff (Q), groundwater extraction (PG), irrigation return flow (IRF), and ultimately changes in groundwater storage (ΔS) in a small semi-arid crystalline representative watershed. Results show that a total of ~?230 mm of groundwater is extracted during 2008–2009, creating a negative impact on the groundwater resource, which is further enhanced by limited recharge and high ET. A decrease of approximately 65 mm in groundwater storage is observed in a single hydrological year, and given a very low specific yield, this decrease will introduce large water level decline. The study establishes that declining groundwater level in the watershed is a direct result of over-extraction, and owing to this scenario, efficient irrigation and land use policies are suggested as potential approaches to minimize extraction specifically in the dry season. Our methodology provides a systematic assessment of vital GWB components at a high spatial resolution and an insight on various sustainable mitigation methods. This methodology is useful in the planning and management of groundwater resources, particularly in water-stressed areas.     

Occupational exposure to pesticides and associated health effects among greenhouse farm workers

Environmental Science and Pollution Research - The number and production capacities of greenhouse farms have been increased across the globe, driven by an effort for addressing food security...