Environmental science. Advances最新文献

This study aims to assess the impact of intensive aquaculture on a lake that has experienced significant anthropogenic impacts. Specifically, it investigates the consequences of aquaculture activities, such as Trapa cultivation (water chestnut) and fish rearing, on the lake's water quality, trophic state, and floristic diversity, with a primary emphasis on algae and macrophytes. Satellite imageries spanning the last five decades, from 1976 to 2022, were analyzed to understand the impact of urbanization and changes in land use and land cover within the lake's catchment. The study found that aquaculture activities negatively impacted algae and macrophytes' diversity, dominance, and community structure in the freshwater lake. The study reported a total of 61 algal species from five families during both sampling phases. Dominant species belonged to the Chlorophyceae and Euglenophyceae families, alongside several diatom species. Notably, the reported algal species served as bioindicators of organic pollution, as assessed by the algae pollution index. During the second year of sampling, intensive fish-rearing activities disrupted the macrophytic diversity, which was replaced by the proliferated growth of planktonic algae, resulting in the biotic shift of the lake's floristic diversity. The study provides valuable insights into the effective management of lakes impacted by intensive aquaculture, shedding light on the intricate relationships between aquaculture practices and the ecological dynamics of freshwater ecosystems in developing countries.

Hexavalent chromium, Cr(VI), is a human carcinogen that occurs in groundwater worldwide. While not federally regulated in the USA, the State of California has approved a new Cr(VI) maximum contaminant level at 10 μg L⁻¹, expected to go into effect fall 2024. This study synthesizes, characterizes, and verifies performance of a hybrid strong base anion exchanger with nanoscale zero valent iron (NZVI-resin) for trace Cr(VI) removal from drinking water. NZVI-resin was synthesized by exchanging tetrachloroferrate ion (FeCl₄⁻) onto the resin prior to sodium borohydride (NaBH₄) reduction. The impact of important synthesis variables was identified, including reagent concentrations and molar ratios, solvent selection, temperature, and drying procedure. Material characterization techniques (e.g. SEM-EDS and XPS) determined NZVI presence and elemental distribution on the resin surface. Our work showed a 360% increase in treated water throughput using NZVI-resin compared to unmodified resin for trace Cr(VI) removal in column experiments. This work presents a broad assessment of the material characteristics of NZVI-resin, discusses the limitations of batch tests, and describes operational challenges for Cr(VI) treatment.

Iron chelating agents have important roles to play, both in human physiology and in the environment. In the latter case, persistence in the environment has given cause for concern in the case of synthetic iron chelating agents such as ethylenediaminetetraacetic acid (EDTA) and diethylenetriaminepentaacetic acid (DTPA), which do not readily biodegrade. Due to their long lifespan in the environment synthetic iron chelators can also participate in mobilization reactions, particularly with radionuclides such as ⁶⁰Co. There is an eminent need to explore alternative iron chelating compounds, preferably, renewable in origin, to overcome the drawbacks of synthetic compounds, making plant biomass a potential source of iron chelating agents. Twelve biomass model compounds, representative of the biomass constituents, cellulose, hemicellulose, lignin and extractives (tannins), were tested for their iron complexation ability by measurement of the binding strengths with Fe(II) and Fe(III) in dimethylsulfoxide (DMSO), to ensure solubility, using spectrophotometric titration. The flavonols, kaempferol, quercetin and myricetin displayed the strongest binding affinity to Fe(II) and Fe(III) along with the greatest positive cooperativity as determined by the calculation of Hill coefficients. The lignin-representative compound, p-coumaric acid, showed the highest binding affinity to Fe(II) only. Carbohydrate model compounds did not show any evidence of binding to iron, despite some contrary evidence in literature about their ability to do so. This study points to the potential role that the flavonols class of compounds, and therefore by extension, plant tissues that are rich in extractives, may play in the exploration of biomass-derived iron chelants.

The abnormally gigantic baobab tree (Adansonia digitata) is often referred to as the “Tree of Life” due to its ability to provide food, water, shelter, and traditional medicine for both humans and animals in arid regions. This special tree is a landmark of Africa's savanna and has attracted the attention of the global research community. This study investigated the potential of biochar derived from baobab seeds for the removal of metallic ions from groundwater. The biochar, prepared at 700 °C, exhibited a unique surface morphology with deep voids and varied structures, suggesting increased surface area and favorable conditions for adsorption. SEM-EDX analyses confirmed the elemental composition, with carbon being the predominant element. Furthermore, XRD analysis indicated an amorphous structure, enhancing adsorption capacity for heavy metal ions. Additionally, BET analysis revealed a significant surface area (1386.704 m² g⁻¹) and well-defined pores, emphasizing the material's potential for metallic ion removal. The metallic ion of choice for this research was Fe because of its abundance in the study area and the community's need for affordable technology for discoloration of reddish-brown groundwater caused by Fe ion presence. In the batch mode equilibrium studies, the effect of pH, contact time, adsorbent particle size, adsorbent dose, solution temperature, and initial metal ion concentration was investigated. Optimal pH metallic ion removal occurred under neutral pH conditions, with higher removal efficiency observed at increased contact time (up to 120 min) and adsorbent doses. Adsorption isotherm modeling using Langmuir and Freundlich models indicated favorable adsorption, with the Freundlich model providing a slightly better fit. In conclusion, baobab seed-derived biochar demonstrated promising potential as an efficient and sustainable adsorbent for metal ion removal from groundwater. Further exploration, including the development of activated carbon and field applications, is recommended for a comprehensive understanding and practical optimization of this material's capabilities for metal ion removal.

Trimethylsiloxane (TriSil) surfactants are promising alternatives to per- and polyfluoroalkyl substances (PFAS), which are global recalcitrant and persistent environmental contaminants, in aqueous film-forming fire-fighting foams (AFFF). However, much less information is available on the environmental fate and degradation of TriSil surfactants. Thus, it is important to study the degradation chemistry of fluorine-free TriSil surfactants in the solution phase under various conditions to further assess their environmental impact. This computational study reports the prominent hydrolysis, reduction, and oxidation pathways of a truncated TriSil and proposes the major degradation products using density functional theory (DFT) calculations. We have identified the polydimethylsiloxane unit of TriSil to play a prominent role in aqueous solution reactivity initiated via hydrolysis and reduction, while oxidation mainly proceeds through H-atom abstraction along the polyethylene glycol unit. The results of this study aid in establishing the use of the alternative fluorine-free surfactant, TriSil, for fire-fighting foams from an environmental perspective.

Plastic litter is ubiquitous in the Arctic marine environment, but knowledge of the importance of specific sources is limited. This project aimed to investigate the input of plastic from untreated sewage discharged to the sea in Greenland. A method was developed to sample and quantify inputs of plastic in different size fractions from wastewater from two towns in Greenland. Plastic findings were visually characterized in terms of abundance, morphology, size, and chemically by characterizing the polymer composition using FTIR spectroscopy. The wastewater was found to be a source of both macro- and micro-sized plastic pollution. Of the total litter load, 70% of the mass was from plastic items larger than 25 mm. Wet wipes were found to be dominating and constituted 59% of the total emitted plastic by mass, but other sanitary items (sanitary pads and condoms) were also detected. A polymeric characterization of the macro-items by ATR-FTIR revealed that the wet wipes were mainly of PET (polyethylene terephthalate, a polyester) but also viscose and cellulose wet wipes were detected. In the microplastic fraction (<300 μm), the main contributor was PP (polypropylene; 65%), but also PE (polyethylene), PES (polyester), PS (polystyrene), cellulose and other polymers were detected. A characterization of the microfibers revealed a large contribution of white/transparent fibers that primarily were composed of cellulose (67%) while a smaller fraction (10%) was polyester (PES), including polyethylene terephthalate (PET). The findings of white/transparent microplastic fibers in the wastewater suggest that a fraction of these fibers is directly related to the presence of the cellulose, viscose and PET wet wipes. Our results suggest that implementing either regulatory or behavioral measures to prevent wet wipes from entering the wastewater or using technical solutions to eliminate the discharge of wet wipes into the marine environment via wastewater, could significantly reduce the emission of plastics of all sizes from wastewater to the marine environment.

Access to electricity is crucial for basic human activities and serves as a direct measure of energy poverty. In recent years, intergovernmental organizations have made significant strides in rural electrification to ensure energy security for all (rural populations, the poor, and the vulnerable). In developing countries, there is a positive correlation between rural infrastructure enhancement and rural livelihoods. Since the early 2000s, in Tanzania, there has been a major government rural electrification initiative to boost rural development. However, the extent to which rural electrification improves rural livelihoods remains unclear. This study was conducted to investigate the impact of rural electrification on household livelihoods in Tanzania, using the Mbulu District as a case study. The study employed a mixed research approach, combining qualitative and quantitative methods. The data were collected from 447 respondents through surveys and interviews with households in electrified and non-electrified areas, where information such as income levels, health, education access, self-employment, and asset ownership was collected. The results indicated a significant 45% increase in household income following electrification compared to non-electrification. About 47% of the respondents earned over 1 000 000 Tsh per month post-electrification, compared to 6% before. Access to modern healthcare improved, with 36% of the respondents being able to afford medication after electrification compared to 13% before electrification. Furthermore, educational opportunities expanded where 31% of the children were enrolled in private schools after electrification compared to 11% before electrification. Asset ownership showed marked improvements, with fewer households living in mud houses (10% post-electrification, down from 22%); all this confirms the significant impact of rural electrification on the improvement of rural development and household livelihood. Our study concludes that rural electrification significantly boosts household income, health service provision, education, and overall welfare which have a significant impact on environmental management. It recommends continued investment and sustained efforts from stakeholders, including the Tanzania Electricity Supply Company (TANESCO) to address challenges hindering electricity service expansion in rural areas. This study provides a foundation for informed policy decisions and actionable strategies to promote sustainable development in rural communities.

The excessive use of emerging contaminants (ECs) in various applications has led to a global health crisis. ECs are found in groundwater, surface water, soils, and wastewater treatment plants at concentrations ranging from ng L⁻¹ to μg L⁻¹. This review explores the sources of ECs and laccase's role in their degradation. ECs encompass diverse categories with potential implications for human health, animals, and the environment, and their adverse effects are examined. Laccase, a key mediator, can oxidize non-phenolic compounds, broadening its substrate range. The review discusses the intricacies of laccase-mediated degradation and highlights its potential to improve global water resource sustainability. Innovative strategies, like laccase immobilization, are explored for EC removal, benefiting environmental preservation. In summary, the review addresses the issue of excessive EC use, their presence in water sources, and their impact on health, wildlife, and the ecosystem. Laccase offers promise for EC degradation, emphasizing its mechanism and potential for sustainable water resource management. Advanced techniques, including laccase immobilization, further demonstrate the commitment to tackling EC-induced environmental challenges.

Visible light-driven motors (Vis-LDMs) have shown significant potential for water decontamination processes through the synergistic interaction between their active movement and photocatalytic properties, enabling more efficient degradation of organic pollutants. This review highlights recent advances in Vis-LDMs photocatalysts for sustainable environmental pollution mitigation. Innovations include fuel-less Vis-LDMs with hybrid structures and crystalline materials, and biofuel alternatives like water and glucose, though logistical challenges persist. The use of natural materials like lignin and cellulose nanocrystals promotes sustainability but faces energy conversion efficiency challenges. Strategies to enhance efficiency, such as doping and heterojunction formation, are discussed. Advances in stability, reuse, and magnetic recovery capabilities are also reviewed. Collective behavior and environmental adaptability are explored to improve catalytic efficiency. Despite the presented advances, definitive solutions to these limitations have not yet been found. A perspective on the directions for future research is also included in this review, namely the need to resolve issues of scalability, cost-effectiveness, and environmental compatibility. Additionally, investing in Vis-LDMs with programmable routes and precise navigation can enhance versatility and accuracy. Selective behavior to target hazardous contaminants is important; the molecular imprinting technique being a potential solution. Future research should also focus on real-world testing and navigation improvements. Overcoming these challenges is essential to fully harness the potential of Vis-LDMs for environmental remediation and global environmental health.

The past several years have witnessed great progress in utilization of industrial waste gypsum. Newly developed carbonation technology toward CaCO₃ preparation also reveals a significant utilization way to recover high-value products from waste gypsum, whereas there is a shortage of systematic reviews reporting the most recent progress in carbonation of flue gas desulfurization gypsum (FGDG). This review provides a timely and comprehensive summary of major achievements regarding FGDG carbonation and calcium carbonate production to address future investigation directions. We start with a brief introduction of FGDG production and utilization approaches in practical use with their advantages and disadvantages. Then we systematically summarize two types of carbonation, including a direct way and an indirect way. The direct way typically involves three steps: CO₂ capture and CO₃²⁻ formation; CaSO₄·2H₂O dissolution; CaCO₃ crystallization. High purity CaCO₃ is prepared and the polymorph of precipitated CaCO₃ is affected by many factors, such as the Ca²⁺/CO₃²⁻ ratio, reaction conditions, impurities, and additives. The indirect way involves gypsum thermal reduction, carbonation, and sulfur recovery. Finally, challenges of current work and perspectives are presented to expedite future industrialization progress and provide a promising research direction for FGDG carbonation.