Environmental science. Advances最新文献

The rising need for rare earth elements (REEs) as critical materials for the development of clean energy technologies, as against the rapid depletion of virgin REE-bearing ores as well as their imbalance in geographical occurrence, calls for thorough search on secondary sources such as coal fly ash, given that the aluminosilicate mineral phase in the waste is enriched in REE particles. To support the geographical diversification of REE sources, there is a need for a comprehensive documentation of REE content and, by extension, the economic potential of fly ash derived from Nigeria's vast coal fields. Eight representative coal fly ash samples generated from coals from Nigeria's major coal belts were collected. Silica and alumina, with respective ranges of 38.1–44.5% and 14–15.98%, accounted for the bulk of the major elements in the samples. Total REE contents in the samples ranged from 874 ppm to 1127 ppm, while the cerium, yttrium, neodymium and lanthanum-dominated rare oxide totals were found to be in the range of 941–2145 ppm across the samples. The outlook coefficients (extractability indices) computed for the samples ranged between 0.8 and 1.3, with 0.7 as the benchmark. The range of percentage of critical REEs in the CFA samples was 28%–36%. This research has successfully explored the relative abundance and distribution of REEs in the studied fly ash samples, providing a theoretical lead for the basis of extraction and waste management.

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Chilli (Capsicum annuum L.) plants are cultivated globally and are valued for their culinary use. One of the major challenges in agriculture is soil salinity, which drastically cuts down crop productivity. However, no information has been reported concerning the effects of biogenic zinc oxide nanoparticles (ZnO NPs), applied as a foliar spray, on the physio-chemical properties of chilli plants under salt stress conditions. The nanoparticles were synthesized using an extract from Acacia nilotica leaves, which acted as a stabilizing and reducing agent. The characteristics of the synthesized nanoparticles were analyzed using various techniques including UV-visible spectroscopy, X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy and X-ray photoelectron spectroscopy. The pot experiment utilized a salinity level of 50 mM NaCl and tested five concentrations of ZnO NPs (0, 25, 50, 75 and 100 ppm). The results demonstrated that the highest concentration (100 ppm) significantly enhanced growth parameters, including the shoot length (38.6%) and root length (25.5%) compared to the control. Additionally, biochemical parameters such as chlorophyll content (23.3%) and phenolic content (12.5%) enhanced zinc accumulation by 38.7% and decreased oxidative stress malondialdehyde (MDA) by 54.4% and hydrogen peroxide (H₂O₂) by 33.1% as compared to the control. We can conclude that foliar application of 100 ppm of the synthesized biogenic-ZnO NPs may increase chilli growth in a salt-stress environment.

Plastics are extensively involved in our everyday lives, including use as food storage containers. Greater than 95% of plastics produced are derived from petrochemicals. Numerous studies have shown that chemical additives (e.g., phthalates) can migrate out of food grade plastics into foods. Based on this we hypothesize that petrochemicals used in the manufacturer of plastics also migrate into foods. To test this hypothesis, we simulated chemical migration from petrochemical-based plastics under refrigeration and microwave conditions using the United States Food and Drug Administration testing guidelines. Specifically, we measured the amounts of polycyclic aromatic compounds (PACs) migrating from four plastics used heavily in the food industry namely polypropylene, polyethylene, polycarbonate and polyethylene terephthalate glycol. Our results showed that several alkylated and non-alkylated PACs could be detected in the food simulant used with relatively greater amounts of the alkylated PACs compared to their non-alkylated analogs. Data from our studies were used to estimate daily intake where it was shown that the greatest risk of exposure to humans stems from migration of PACs from PE into foods with total EDIs of 1794.4 ± 163.5 and 169.4 ± 23.5 ng per person per day under refrigeration and microwave conditions, respectively. Finally, an assessment of human health risk resulting from dietary exposure to PACs migrating from the four plastics studied under the two usage scenarios, suggests that at current exposure levels, PACs pose negligible cancer risk to humans.

Microplastic pollution constitutes a pressing global environmental issue impacting nearly every facet of human activity. This specific environmental challenge exerts profound yet still poorly understood influences on health, social dynamics, and industrial practices. A major obstacle for further investigation and mitigation of microplastics lies in their heterogeneity in size and composition. Additionally, the multitude of sources contributing to microplastic emissions further complicates their study. To enhance current detection and analytical methodologies for microplastics, this study exploits a novel approach for the easy and specific identification of microplastics within diverse environmental samples (including air, soil, lake water, rain, snow, and marine sediment) collected from various geographical locations across Canada. This method relies on fluorescent conjugated polymer nanoparticles that can be used to identify microplastics after minimal preparation. In all examined samples, originating from diverse sources and environments, microplastics were consistently present in the form of fragments and/or fibers, with polyethylene terephthalate (PET) emerging as the most abundant type, as confirmed via Raman spectroscopy either before or after labeling. This approach significantly streamlines the microplastic identification process, reducing the time needed for extraction and isolation. Our findings corroborate the efficacy of nanoparticle labeling for microplastic detection, offering promising avenues for their facile, specific, and reliable identification. Ultimately, this novel procedure holds potential to enhance remediation efforts targeting microplastics in the environment, thereby advancing our understanding of their global impact.

Microplastics (MPs), discharged from wastewater treatment plants (WWTPs), are found abundantly in freshwater systems. Along with MPs, various microorganisms that evade WWTP disinfection may colonize these particles, leading to biofouling. This study assessed the performance of six bacterial strains isolated from wastewater and the factors influencing biofilm formation using synthetic freshwater and polyethylene (PE) microplastics as a model. The effect of two PE microplastic sizes (180–200 μm and 3–4 mm) and three flow velocities (0.238, 0.11, and 0.077 m s⁻¹) were tested on the isolated strains' microbial growth and biofilm formation. Smaller MPs notably enhanced the growth rate. The treatment with small PE microplastics and a low flow velocity promoted the biofilm formation compared to a higher flow velocity where rapid microbial growth was observed but showed a lower biofilm formation after seven days of cultivation. These findings reveal how MP size and flow velocities influence biofilm development, advancing the understanding of MP-microbial interactions in freshwater aquatic environments.

The use of treated effluent/wastewater (TWW) for crop irrigation is gaining prominence globally due to growing freshwater scarcity. However, there are still questions about the safety of such a practice. This study sought to investigate and evaluate the health risks associated with the use of TWW for crop irrigation by assessing the potential risks arising from pathogens, heavy metals/potentially toxic elements (PTEs), micropollutants or pharmaceuticals and antibiotic resistance genes (ARGs), using tomato, carrot and cabbage as test crops. The levels of copper bioaccumulated in TWW irrigated crops were 25 mg kg⁻¹ for tomato, 30 mg kg⁻¹ for carrot and 20 mg kg⁻¹ for cabbage, while those of the control (tap water) were 30 mg kg⁻¹ for tomato, 40 mg kg⁻¹ for carrot and 65 mg kg⁻¹ for cabbage, respectively. Arsenic, cadmium and lead levels were below the detection limit for all treatments. The hazard quotient (HQ) and hazard index (HI) of copper and zinc were below 1 (adults) for TWW irrigated crops. Escherichia coli, Clostridium perfringens, coliform and thermotolerant bacteria were not detected on the fruits of tomato plants irrigated with TWW. All analysed pharmaceuticals were below the limit of detection except gabapentin, which was 3 μg kg⁻¹ in TWW irrigated tomatoes. tetA, ermB, bla_TEM, sul2, sul3 and qnrS genes were found in the metagenomic DNA extracted from TWW- and tap-irrigated cabbage. The results indicate no potential non-carcinogenic health risk for adult consumers and no microbial contamination of the tomato fruits under TWW irrigation. No difference was observed in the presence and distribution of the ARGs between TWW- and tap-irrigated crops, suggesting no contribution to the diffusion of different ARGs due to irrigation. Altogether, these findings highlight that health risk assessment of TWW for crop irrigation should focus on the quality of the TWW and on soil characteristics, which may contribute to risk exposure of different types of contaminants.

Harmful algal blooms (HABs) are a threat to aquatic ecosystems worldwide. New information is needed about the environmental conditions associated with the aerosolization and transport of HAB cells and their associated toxins. This information is critical to help inform our understanding of potential exposures. We used a ground-based sensor package to monitor weather, measure airborne particles, and collect air samples on the shore of a freshwater HAB (bloom of predominantly Rhaphidiopsis, Lake Anna, Virginia) and a marine HAB (bloom of Karenia brevis, Gulf Coast, Florida). Each sensor package contained a sonic anemometer, impinger, and optical particle counter. A drone was used to measure vertical profiles of windspeed and wind direction at the shore and above the freshwater HAB. At the Florida sites, airborne particle number concentrations (cm⁻³) increased throughout the day and the wind direction (offshore versus onshore) was strongly associated with these particle number concentrations (cm⁻³). Offshore wind sources had particle number concentrations (cm⁻³) 3 to 4 times higher than those of onshore wind sources. A predictive model, trained on a random set of weather and particle number concentrations (cm⁻³) collected over the same time period, was able to predict airborne particle number concentrations (cm⁻³) with an R squared value of 0.581 for the freshwater HAB in Virginia and an R squared value of 0.804 for the marine HAB in Florida. The drone-based vertical profiles of the wind velocity showed differences in wind speed and direction at different altitudes, highlighting the need for wind measurements at multiple heights to capture environmental conditions driving the atmospheric transport of aerosolized HAB toxins. A surface flux equation was used to determine the rate of aerosol production at the beach sites based on the measured particle number concentrations (cm⁻³) and weather conditions. Additional work is needed to better understand the short-term fate and transport of aerosolized cyanobacterial cells and toxins and how this is influenced by local weather conditions.

Access to clean water is under threat due to population growth, climate change, and pollution, emphasizing the need for effective wastewater treatment. Wastewater pollutants pose risks to public health and ecosystems, necessitating proper treatment methods. This paper outlines both conventional and emerging technologies for wastewater treatment. Established techniques, such as activated sludge processing, chlorination, and constructed wetlands, are discussed alongside newer methods, such as advanced oxidation, ultraviolet disinfection, membrane bioreactors, reverse osmosis, artificial intelligence optimization, and nanofiltration, which enhance contaminant removal but may incur high costs and energy demands. Integration of renewable energy sources, such as solar, wind, and biomass, into treatment facilities improves efficiency and reduces emissions. The process efficiency can be possibly enhanced through real-time monitoring and automation, while a sustainable and resource-efficient method involves integrating bio-electrochemical systems with constructed wetlands. There are still challenges in sludge handling, land requirements, and long-term system maintenance. Balancing technological solutions, environmental protection, and economic feasibility is essential for sustainable wastewater management, which can ensure continuous access to clean water in the face of increasing demand for this vital resource.

In January 2022, gaseous elemental Hg (GEM) concentrations were continuously monitored at Syowa Station on East Ongul Island, located ∼4 km from the continent on the eastern coast of Lützow-Holm Bay, to examine atmospheric Hg concentrations during the summer in the southeastern Antarctic region. Atmospheric GEM ranged from 0.36 to 1.83 ng m⁻³ average value: 1.01 ± 0.21 ng m⁻³ and increased during the day and decreased at night. While maintaining these diurnal variations, GEM concentrations increased to 1.99 and 1.55 ng m⁻³ on January 2–3 and 17–20, 2022, respectively. During both events, the low-pressure system approached the Syowa Station, and the 72 hours backward trajectory analysis revealed that the air mass originated from open water surfaces, implying that Hg evasion from the sea surface increased the atmospheric GEM concentration. To investigate the causes of diurnal variation causes—excluding these two events mentioned—Hg concentrations in the soil [n = 102, 2.61 ± 3.16 (0.14–19.0) ng g⁻¹], snow, glacier, and ice sheet around Syowa Station (n = 19, 0.45–5.60 ng L⁻¹), as well as in the atmosphere on the fast ice around the station (0.54–1.10 ng m⁻³), were measured. The results revealed that sources such as ornithogenic soil from the penguin rookery around the station, open water surfaces, and the gaseous oxidized Hg transported inland by katabatic winds did not contribute to the daytime GEM concentration increases. The cause of the summer diurnal variation at Syowa Station was unidentified and warrants further investigation.