Environmental science. Advances最新文献

The current study, conducted over a year, involved a comprehensive analysis of water samples from the Rainha River. This river crosses the Pontifical Catholic University of Rio de Janeiro Campus to assess water quality and potential applications. The samples underwent rigorous physical–chemical tests, including metal concentrations, pH, turbidity and toxicity assessments. The water collected and analysed by the standards proposed by CONAMA was found to be below the limit of regulation, classified at class 1, and requiring only a simplified treatment to remove microorganisms and achieve potability. Toxicity tests using Saccharomyces cerevisiae were performed to examine biological effects, revealing no significant toxicity. The next step was to design a water treatment plant, following the viability, water studies and identification. The process involved designing a block diagram and, later, the process flow diagram (PFD). The processes consist of getting water, passing through microfiltration, decontaminating it with hypochlorite, and using adsorption methods to turn it into a potable and useable on campus, thereby ensuring a safe and sustainable water supply for the university community.

Hydrazine is a very toxic chemical that poses a major threat to human health and the environment. As a further expansion of our ongoing research, this report validates the enhanced real-time hydrazine sensing using benzothiophene-based semi-bis-chalcone (SBC). Hypothesized SBC molecules that can be easily attacked by nucleophilic groups were synthesised via classical Claisen–Schmidt condensation. Two derivatives of novel SBC scaffolds were synthesised by the reaction of simple acetone with benzothiophene carbaldehydes. This reaction involved the use of KOH and pyrrolidine as catalysts, and they demonstrated two different processes in comparative studies. KOH worked as a speedy catalyst, while pyrrolidine was demonstrated to be a more efficient catalyst. The structures of the synthesised compounds were established by various spectral techniques. The optical properties of the prepared SBCs were studied in different solvent systems and demonstrated that methanol was the more suitable solvent. Density functional theory (DFT) calculations of both compounds in methanol were performed using the Gaussian software. Time-dependent density functional theory (TDDFT) calculations were performed to study the dynamic behaviour of electrons in both molecules and materials by considering their density as a function of time. Both DFT and TDDFT calculations were observed to have a good correlation with the experimental results. The obtained absorption and photoluminescence results and their theoretical correlation suggested that the prepared SBCs can be optimized for applications in optoelectronics, sensing, and bioimaging. As an improvement to our earlier protocol, more efficient real-time hydrazine sensing SBCs probes were established with prolonged π-conjugation. An exhaustive protocol with a working pH range, analyte selectivity, and real sample test was developed. The studied SBCs showed a broad working pH range and excellent hydrazine sensing selectivity. With these two included in our large library of photoresponsive molecules, we aim to construct a model device for hydrazine sensing in real life applications.

Effect-based methods (EBM) are of growing interest in environmental monitoring programs. Few EBM have incorporated transcriptomics even though these provide a wealth of biological information and can be modeled to yield transcriptomic points of departure (tPODs). The study objectives were to: (A) characterize cytotoxic effects of soil extracts on the rainbow trout RTgill-W1 and the human Caco-2 cell lines; (B) measure gene expression changes and calculate tPODs; and (C) compare in vitro responses to available measures of plastic-related compounds and metals. Extracts were prepared from 35 soil samples collected at the Agbogbloshie E-waste site (Accra, Ghana). Cells were exposed to six soil concentrations (0.3 to 9.4 mg dry weight of extract (eQsed) per mL). Many samples caused cytotoxicity with RTgill cells being more sensitive than Caco-2 cells. Eleven samples were analyzed for transcriptomics in both cell lines, with responses measured in all samples (52 to 5925 differentially expressed genes) even in the absence of cytotoxicity. In RTgill cells there was concordance between cytotoxic measures in tPOD values (spearman = 0.85). Though trends between in vitro measures and contaminant data were observed, more work is needed in this area before definitive conclusions are drawn. Nonetheless, this study helps support ongoing efforts in establishing alternative testing strategies (e.g., alternative to animal methods; toxicogenomics) for the assessment of complex environmental samples.

Biodegradable plastic offers an alternative to conventional plastic for use in agriculture. However, slower degradation in the environment compared to industrial composting and high production of microplastics is of growing concern and poses the question whether they represent a viable replacement. It remains unclear whether observed effects of biodegradable plastics on the soil microbial community and plant nutrient uptake are from biodegradation or from the abiotic effects of the microplastics themselves. The aim of this study was to quantify the biodegradation of the bioplastic poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), at increasing microplastic loadings (0.06–3.2% w/w) via pyrolysis/gas chromatography-mass spectrometry (Py/GC-MS) alongside effects on soil health and plant growth (Zea mays L.). Between 1.5 and 5% of PHBV microplastic was degraded in soil after 8 weeks, with the rate declining with increasing PHBV concentrations due to microbial nitrogen (N) limitation, demonstrated by increased investment in N-cycling enzymes. Plants were also limited by both N and phosphorus (P). Greater extractable soil ammonium and nitrate contradicted N limitation, however, increases in soil hydrophobicity likely limited mobility, and thus plant and microbial utilisation. As a result, increased C from PHBV degradation did not result in a concurrent increase in microbial biomass, which was reduced under higher PHBV microplastic loading, indicating low microbial carbon use efficiency. While high PHBV microplastic loadings resulted in significant effects on the microbial community size and structure, soil properties and plant growth, there were minimal effects at low PHBV concentrations (0.06% w/w). Observations of nutrient limitation at higher plastic loadings has significant implications for the design of standard biodegradation assays, which must consider both abiotic and biotic effects of microplastic on soil nutrient cycling.

Municipal wastewater treatment plants (WWTPs) with sequencing batch reactors (SBRs) face many challenges due to organic shock load (OSL) flocculation caused by population growth and industrialization. Guaranteeing that effluent quality remains within regulatory limits is vital for environmental protection and public health. Using conventional methods for managing variations in OSL faces a lot of difficulties, specifically when it comes to accurately predicting the effluent quality that complies with regulatory standards. This study addressed this by integrating a machine learning (ML) model, to anticipate how varying OSL can affect the effluent quality of an operational SBR WWTP located in Egypt. The novelty of this research lies in using ML to predict the system's performance when applied to different OSL scenarios, showing a dynamic method for SBR optimization operations. Initial trials with OSL values of 2× and 1.6× the actual influent levels resulted in non-compliance with regulatory standards, whereas the optimal OSL was determined to be 1.3×. The study illustrates that the incorporation of ML into the process results in superior plant performance and greater decision-making amid variable settings, presenting an innovative approach for employing data-driven models in municipal wastewater treatment, and yielding fresh perspectives on the improvement of WWTP operations.

The present work unveils a process to synthesize silver (Ag) and copper (Cu) doped zinc oxide (ZnO) nanoflowers for photocatalytic and antibacterial applications. Leucophyllum frutescens leaf extract (LFLE) was used for the rapid and efficient green synthesis of nanoparticles (NPs). The current study provides new insight into the fabrication of uniform exotic NPs with tunable size and shape that control their photocatalytic and therapeutic potential. UV-visible and photoluminescent spectroscopy exhibited the optical properties. The energy bandgap of 3.36 eV in the ZnONPs was reduced to 3.26, 3.21, and 3.24 eV, in Ag@ZnONPs, Cu@ZnONPs, and Ag–Cu@ZnONPs, respectively as calculated from the Tauc plots. Field-emission scanning electron microscope and high-resolution transmission electron microscope images revealed the flower-shaped morphology of the NPs. At the same time, energy dispersive spectra and elemental mapping confirmed the presence of Zn, O, Ag, and Cu in the respective NPs. X-ray diffraction confirmed the crystalline nature with the average crystallite size being 12.75 nm, 11.22 nm, 13.14 nm, and 13.23 nm for ZnONPs, Ag@ZnONPs, Cu@ZnONPs, and Ag–Cu@ZnONPs. Photocatalytic degradation of methylene blue dye was maximum in the Ag–Cu@ZnONPs that closely fitted with the pseudo-first-order reaction kinetics. Additionally, the Ag@ZnONPs with a higher aspect ratio due to smaller size resulted in superior antibacterial activity and synergy with antibiotics against Bacillus subtilis, Staphylococcus aureus, and Pseudomonas aeruginosa. The results confirm the nanobiotechnological potential of L. frutescens which can be used for environmental remediation.

The growing demand for food production worldwide has led to the increased use of fertilizers contributing to a range of environmental problems. To reduce these problems, the development of urea–hydroxyapatite (HAP) materials as nutrient-efficient fertilizer carriers has gained considerable attention as a more nutrient-efficient alternative to conventional nitrogen (N) and phosphorus (P) fertilizers. Conventional N fertilizers, such as urea, possess high solubility and rapidly release nitrogen leading to significant nutrient losses through leaching and volatilization. Conventional P fertilizers suffer from quite the opposite problem: they are quickly immobilized in soil and P release becomes very slow. HAP is a naturally occurring mineral and has been postulated, at the nanoscale, to release P at a controlled rate although risks associated with HAP nanoparticle occupational and environmental toxicity remain. HAP/urea hybrid materials present a unique opportunity for N–P–(Ca) fertilizer material design where innate properties of the parent materials, urea and HAP, are altered due to the purported chemical interactions, thus resulting in a novel and improved nutrient management paradigm. This review summarizes the developments in their synthesis, nutrient release and plant uptake while scrutinizing the reported underlying chemical interactions between both parent compounds, critical to the enhanced efficiency in soil.

Saline wastewaters mainly result from various industrial activities. In response to water shortage, seawater is increasingly utilized for diverse purposes, leading to an increased production of saline wastewater. The presence of salts in wastewater frequently impairs the efficiency of biological wastewater treatment technologies. Among these, aerobic granular sludge (AGS) has emerged as the most effective aerobic biological treatment process for treating saline wastewater, primarily due to the high biomass aggregation and self-protection afforded by granules. In this study, the AGS biomass was acclimated to saline wastewater through a slow stepwise salt increment strategy over a period of ca. 250 days, from 0 to 14 g NaCl L⁻¹. This acclimation strategy facilitated stable and efficient removal of carbon (>90%), phosphorus (>95%), and ammonium (>98%), without nitrite accumulation in the effluent. Notably, it was observed that the increase in extracellular polymeric substance (EPS) content was concomitant with the enrichment in EPS-producing bacteria, in the AGS biomass. Other salt tolerant bacteria were also enriched in the biomass, particularly those from the Lysobacter and Rhodocyclus bacterial genera, related to nutrient removal and AGS stability. Besides, the high nutrient removal performance was corroborated by the identification of bacteria responsible for these processes. Thus, by employing a slow stepwise increase of wastewater salinity, the AGS process successfully adapted by maintaining the metabolic diversity necessary for various biological removal processes. This study underscores the microbial selection and plasticity inherent in AGS processes, highlighting their significant potential for upgrading saline wastewater treatment.

Bimetallic nanoparticles provide promising active sites for many reactions, and such materials can be synthesized with different spatial distributions, such as disordered alloys, core–shell structures, and Janus-type heterogeneous structures. Catalytic activity, selectivity, and stability of bimetallic nanoparticles can be modified by the geometric, electronic, multifunctional and mixing effects, as compared with single metals. Accurate control of bimetallic compositions and their distributions is crucial to obtain high-performance catalysts. The present review summarizes the recent advances in preparation methods and catalytic applications of supported bimetallic nanomaterials. In addition, representative case studies are also provided to investigate how bimetallic nanoparticles can be used as desired catalysts and how specific functional catalysts are designed for targeted reactions. The structure–performance relationships of supported bimetallic catalysts for a number of reactions are discussed to achieve a fundamental understanding. Synthetic strategies and perspectives for precise control of bimetallic active components and element distributions with distinctive nanostructures are proposed for potential industrial applications.

Cadmium contamination of ground water and soil has drastically increased in some areas through the last few decades and remediation strategies are currently being investigated. The coupled dissolution–precipitation of calcium carbonate in cadmium-containing solutions leads to the precipitation of a (Ca,Cd)CO₃ phase of lower solubility, this process trapping cadmium from a solution into a solid phase. The present study analyses the reactions of two types of calcium carbonates (calcite as Carrara marble and aragonite) in cadmium solutions and compares the different reaction pathways and their respective efficiency. X-ray tomography scans of different Carrara marble and aragonite samples reacted in cadmium solutions for 16 to 64 days at 200 °C were acquired and analysed. The reaction in Carrara marble proceeds through a dissolution–precipitation reaction from the surface of the sample. The fluid moves through the porosity developed in the newly precipitated phase and along grain boundaries. Tomograms show that the porosity at the post-reaction time of imaging is mainly disconnected and that the reaction extent decreases with an increase in cadmium concentration of the solution. For aragonite, the main reaction pathway is opened by reaction-induced fracturing, which leads to a faster reaction than for the Carrara marble as the reaction pathways open faster towards the centre of the sample through successive hierarchical fracturing. The reaction rate for aragonite increases with time and cadmium concentration of the solution. Thus, the sequestration of cadmium from solution is potentially more efficient using aragonite due to the reaction-induced fracturing process taking place.