环境•农林最新文献

The present study aimed to use Eucalyptus leaves extract for the green synthesis of ZnO oxide (ZnO) nanorods (NRs) using the hydrothermal method. The X-ray diffraction (XRD) patterns confirmed that the ZnO NRs had a hexagonal crystal structure with high crystal quality. FTIR analysis revealed the presence of functional groups associated to the formation of ZnO NRs. The optical band gap was calculated using the Tauc plot. Scanning electron microscopy (SEM) revealed rod-like morphology of the as-fabricated ZnO, which is further confirmed by the transmission electron microscopy (TEM) analysis. Furthermore, the biosynthesized ZnO NRs were used as photocatalysts for degradation of Rhodamine B (RhB) dye under ultraviolet radiation. Based on these results, ZnO NRs with a concentration of 20 mL of the eucalyptus extract revealed exceptional performance with a photocatalytic degradation rate of 94.77% under UV irradiation for 90 min. According to these results, wastewater can be treated effectively via the designed catalysts using the green and facile synthesis techniques.

The molybdenum doped mixed metal oxides such as zinc and cobalt (Mo/ZnCo₂O₄) were synthesized in a simple hydrothermal procedure that required no use of an expensive and toxic solvent but it exhibited the low photocatalytic efficiency. As-produced Mo/ZnCo₂O₄ were hybridized with reduced rGO to form Mo/ZnCo₂O₄/rGO nanoarray to remove above mentioned issues. Methylene blue (MB) was used in photocatalytic research because it is a common organic contaminant and create very detrimental effect on the living and environmental components. Degradation percentages for ZnCo₂O₄, Mo/ZnCo₂O₄, and Mo/ZnCo₂O₄/rGO nanocomposites were determined to be 41.17, 78.45 and 91.47%, respectively. As per the findings, the aqueous MB dye underwent oxidation primarily due to the presence of the superoxide (({O}_{2}^{bullet -})) radical. The nanocomposite photocatalysts exhibited photodegradation efficiency exceeding 91.47% and displayed remarkable stability, as evidenced by the absence of any noticeable decline in activity indicated by the repeatability test (five cycles). Furthermore, Mo/ZnCo₂O₄/rGO displays excellent antimicrobial activity toward the S.aureus and E.coli species. Our finding suggests that the Mo/ZnCo₂O₄/rGO nanostructure can act as a potential antimicrobial and photocatalytic agent.

The main aim of this study was the removal of heavy metal ions, namely aluminium (Al³⁺), chromium (Cr³⁺), zinc (Zn⁺²), lead (Pb²⁺) and arsenic (As³⁺) from metal plating wastewater using electrocoagulation (EC) technique. The Fe–Fe and Fe-Cu electrode pair configuration was used in the reactor. The influence of electrode material, EC time and wastewater pH on removal performance was investigated. The results showed that the heavy metal removal efficiency was higher when using the Fe-Cu electrode pair. Over 90% of heavy metal ions (Cr³⁺, Zn⁺², Pb²⁺ and As³⁺) were removed efficiently by conducting the EC treatment at current density (CD) of 12.6 mA/cm², pH of 6.2 and EC time of 30 min. These operating conditions led to specific energy consumption and specific amount of dissolved electrodes of around 20 kWh/m³ and 0.87 kg/m³, respectively. The kinetic study showed that the removal of such heavy metal ions follows pseudo first-order model.

Microplastics (MPs) and heavy metals are significant pollutants affecting aquatic ecosystems in Bangladesh, with potential ecological and human health implications. This study investigates the occurrence and characteristics of MPs and heavy metal contamination in Tenualosa ilisha (riverine shad) from the Meghna River Estuary in the northern Bay of Bengal. MPs abundance varied from 17 to 38 particles/fish sample with a mean of 10 items/fish sample. MPs show variations in shape, size, and color. The occurrence of 189 MPs from the visually identified 210 microplastic-like particles were confirmed by µ-Fourier Transformed Infrared Spectroscope (µ-FTIR). In addition, 12 heavy metals, including arsenic (As), lead (Pb), cadmium (Cd), and iron (Fe), were quantified in different body parts (head, flesh, and bones). The concentration was found as As ˃ Fe ˃ Mn ˃ Cu ˃ Ni ˃ Pb ˃ Mg ˃ Se ˃ Co ˃ Zn ˃ Cd ˃ Hg in all parts (head, flesh and bones) of the fish samples. Significant differences in MPs and metal concentrations were observed based on fish size and body part. PCA analysis revealed distinct patterns of metal accumulation across different body parts and fish sizes, with larger fish showing higher levels of Pb and Cu, indicating prolonged exposure. Hierarchical clustering further highlighted similarities in metal distribution, grouping metals such as Pb and Cd due to common sources or pathways of accumulation. The results emphasize the potential health risks associated with consuming larger Hilsa fish due to the occurrence of elevated levels of heavy metal and MPs. To tackle this, the need for regular monitoring of both MPs and heavy metals in anadromous fish species in Bangladesh's aquatic environments is quite apparent.

This study investigated river foam that accumulated on river edges and amongst in-stream debris in the Belubula River, an endangered ecological community and known habitat for platypus, draining a mostly agricultural catchment to the west of the Great Dividing Range in NSW. Samples of both water and accumulated foam from the river were tested for 15 metals and five per- and poly fluoroalkyl substances (PFAS) of which only perfluorooctane sulfonate (PFOS) was detected. The concentration of PFOS in foam (median 375,000 ng/L) was 18,750 times greater than in water (20 ng/L). Metals in river foam were more abundant than in river water. The median copper in river water was 3 µg/L and nearly 1000 times greater in river foam (median 2900 µg/L). Several metal toxicants (including mercury, cadmium, selenium and lead) were only detected in river foam where they were orders of magnitude higher than ecosystem protection levels. We speculate that aeration of river flow through rapids and waterfalls contributed air bubbles that produced surface foam in a similar process to foam fractionation. Although foam containing PFOS has previously been documented within a freshwater lake, the hyperaccumulation of metals within PFOS-enriched foam on the surface of a river appears to be a novel phenomenon and warrants further investigation to determine the bioavailability of the hyperaccumulated chemicals. In addition to the potential ecological impacts from such highly contaminated foam, it also poses potential human-health and agricultural pollution risks.

Microplastics have increasingly become a global menace, pervading aquatic ecosystems and exerting profound biological impacts on marine life. The breakdown of synthetic fabrics, consumer plastics and industrial trash is the source of these contaminants. Due to an inappropriate disposal and fragmentation procedures, these plastic waste materials end in aquatic bodies. While numerous studies have focused on studying the effects of various plastics, limited research has focused on low-density polyethylene (LDPE) MPs and their unique way of interaction with biota. In this study, pigmented LDPE plastics were separated into three distinct size ranges (> 10 µm, 10–15 µm, and 15–25 µm), characterized and exposed to zebrafish for 48 h at a concentration of 1 µg/ml. The following developmental endpoints were analyzed and assessed: histopathological changes, gastrointestinal enzyme activity (trypsin, chymotrypsin, carboxypeptidase A, α-amylase, and lipase), biochemical responses (superoxide dismutase, lipid peroxidation, and catalase) and embryo survival and hatching rates. Although LDPE MP exposure did not cause embryo death, it did cause a decrease in hatching rate, an increase in heart rate, a considerable accumulation of MPs in the gut and significant tissue damage, especially by the smallest particle size. These results demonstrate how colored LDPE MPs may jeopardize aquatic creatures’ biological integrity, posing a growing risk to aquatic ecosystems and public health.

Access to clean drinking water is a key objective of the United Nations'Sustainable Development Goals (SDGs), adopted in 2015. Achieving this target by 2030 necessitates various approaches to ensure adequate drinking water facilities, especially in rural areas prone to water scarcity. In this context, the development of self-reliant household drinking water facilities is gaining traction as a cost-effective and immediate solution for providing clean and safe drinking water. These facilities are essential due to the presence of hazardous contaminants such as dirt, bacteria, viruses, pathogens, and emerging organic as well as inorganic pollutants that result from the improper disposal of wastewater into natural streams, posing significant health risks with prolonged exposure. This review examines the different types of household drinking water filters currently in use and their modifications aimed at removing specific contaminants. It highlights their significance as sustainable solutions, emphasizing mitigation strategies that employ eco-friendly and cost-effective materials. Furthermore, the review elaborates on the potential removal efficiencies of these filters, demonstrating their effectiveness as point-of-use (POU) treatment solutions.

Polyfluoroalkyl substances (PFAS) are persistent, bioaccumulative, and toxic compounds that pose significant environmental and health risks. Although PFAS contamination has been extensively studied in high-income countries, there is limited data on its occurrence and impact in low and middle-income countries, particularly in Africa. This study addresses the lack of comprehensive data on PFAS in wastewater treatment plants (WWTP), surface water, and sediments in Pretoria (South Africa), to inform pollution control strategies and health risk assessments. The Apies River in Pretoria, which receives treated effluent from nearby WWTPs, was selected for investigation due to its importance to local communities and potential exposure to PFAS. Samples were collected during the dry season weekly on days 1, 7, 14, and 21, to investigate temporal variations in PFAS concentrations in treated effluent, sediment, and surface water, and analysed for legacy and emerging PFAS. Sampling during the dry season provides an opportunity to detect and quantify PFAS more effectively as they are less likely to be diluted by rainfall. PFAS were recovered from the samples using solid-phase extraction followed by liquid chromatography-tandem mass spectrometry. The results showed that the ΣPFAS concentrations were consistently higher in treated effluent samples over 21 days. Long-chain PFAS concentrations were significantly different (p < 0.05) between upstream and downstream locations. Perfluorocarboxylic acids were consistently found at higher concentrations in treated effluent, surface water, and sediment samples, with surface water (downstream) showing the highest concentration (62.98%). Sediment samples upstream (31.44%) and downstream (29.24%) showed a higher percentage of perfluorosulfonic acids, indicating stronger sediment adsorption. The findings of this study will drive future research and policy development focused on protecting water resources in South Africa’s waterways.

Phytoremediation assisted by endophytic bacteria is a promising strategy to enhance the remediation efficiency of heavy metals in contaminated soil. In this study, the capacity and role of the endophytic Bacillus sp. D2, previously isolated from Commelina communis growing near a copper (Cu) mine, in assisting the phytoremediation were evaluated. Results showed that inoculation of Bacillus sp. D2 significantly enhanced the biomass production of C. communis by 131.06% under high level of Cu stress. Additionally, the oxidative damages caused by Cu toxicity in C. communis tissues were alleviated as evidenced by significant reductions in malondialdehyde (MDA), superoxide anion (O₂^•−) and proline content following Bacillus sp. D2 inoculation. Meanwhile, the activities of antioxidant enzymes in plant leaves presented upward trends after Bacillus sp. D2 inoculation. Notably, Bacillus sp. D2 inoculation significantly decreased Cu uptake and translocation by C. communis, while enhancing the Cu stabilization in contaminated soils. Furthermore, soil enzyme activities (acid phosphatase, catalase, and urease), as well as the richness of soil bacterial communities in Cu-contaminated soil increased following Bacillus sp. D2 inoculation. Importantly, the inoculation specifically augmented the relative abundance of key bacterial taxa (including Pseudomonas and Sphingomonadaceae) in the rhizosphere soil, which was positively correlated with soil nutrients cycling and plant growth. Our findings suggest that the endophytic strain Bacillus sp. D2 can strengthen the phytostabilization efficiency of Cu by C. communis through its beneficial effects on plant physio-biochemistry, soil quality and bacterial microecology, which provides a basis for the relative application to Cu-contaminated soils.

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