Environmental Chemistry Letters最新文献

Scandium has been used to distinguish between natural and anthropogenic sources of lead to the atmosphere. Here, scandium is used to estimate the natural abundance of lead in surface and groundwater. In pristine groundwater sampled at the Elmvale Groundwater Observatory in southern Ontario, the lead/scandium mass ratio (Pb/Sc) ranges from 1.1 to 1.2, similar to the ratio (1.2) most recently proposed for the Upper Continental Crust. In the Athabasca River of northern Alberta, where dissolved lead is well below the global average for uncontaminated river water, the average Pb/Sc ratio was 2.2 in 2014 and in 2015, consistent with the Pb/Sc ratio recently compiled for soil (2.3). In contrast, the average Pb/Sc ratio in the rivers and lakes of central Ontario was 6.0, reflecting the far larger cumulative inputs of anthropogenic, atmospheric lead in eastern Canada compared to western Canada. Support for this interpretation comes from contemporary snow from southern Ontario with an average Pb/Sc ratio of 400. Despite the profound differences in the geology of the study regions, and ignoring the geochemical processes affecting both elements in the watersheds, scandium appears to be a helpful, simple tool for estimating the natural abundance of lead in surface and groundwater. However, the use of the Pb/Sc ratio in this way depends critically on accurate, precise and sensitive measurements of both elements. While the problems of low level lead determinations are well known, those of scandium may have been underestimated.

Oxocarboxylic acids are produced when oil is exposed to sunlight and are photo-dissolved in the aqueous phase in oil–water systems, impacting the fate, transport, and impact of spilled oil. However, temperature effects on these reactions are unknown, thus we investigate oxocarboxylic acid photoproduction from irradiated oil–water systems. Oil samples include British Petroleum crude, Deepwater Horizon crude, Maya crude from Mexico, SRM 2717a oil from the National Institute of Standards and Technology, and an Alaskan crude. Oils were spread over water and exposed to simulated sunlight for 6 h at 12, 25, and 35 °C, followed by quantifying oxocarboxylic acid abundance and dissolved organic carbon in the water. Treatment with 2,4-dinitrophenyl hydrazine produced hydrazones, enriched using solid phase extraction and analyzed by using electrospray ionization-tandem mass spectrometry. Results show that temperature and oxocarboxylic acid photoproduction exhibit a complex relationship; however, oil behavior was similar with temperature. Dissolved organic carbon increased with irradiation temperature for photosolubilized oil. Deepwater Horizon oil showed high-temperature sensitivity with dissolved organic carbon production of 12.6 ppm at 35 °C versus 6.0 ppm at 12 °C. Low molecular weight species are easily volatilized, while larger molecules require greater photooxygenation to become substantially water soluble.

Traditional Chinese medicine has a rich history in the diagnosis and treatment of diseases, yet the disposal of medicine residues by incineration and landfilling is challenging. Here we review methods to recycle Chinese medicine residues with focus on challenges, recycling solutions, and case studies. Cases studies include extraction of bioactive compounds, use as feed additives, and biochar-based materials. We observed that residues from single-compound medicines are easier to extract and recycle into animal feed additives or adsorbents. Technical and economic analysis show that the valorisation of single-compound medicine residues is profitable. For instance, the re-extraction cost of flavonoids is 25.8–36.6% lower than the market price, and the cost as feed additives represents 14.7% of the market prices.

Carbon emissions from the water and wastewater treatment sector account for about 2% of global carbon emissions, calling for the integration of sustainable energies to decrease carbon footprints. Here we review the use of hydrovoltaic technologies in water and wastewater treatment, with emphasis on the hydrovoltaic effect, self-powered sensors, and pollutant removal. The hydrovoltaic effect can be obtained using moisture-induced hydrovoltaic generators and water evaporation-induced hydrovoltaic generators. Strain, pressure, humidity, gas, and liquid sensors can be powered by hydrovoltaic generators. Remarkably, the hydrovoltaic technology-driven liquid sensors can reach a detection limit of 1 femtomolar. The hydrovoltaic technology reduces pollution in two ways, first by generating electricity from environmental moisture and evaporation, thereby reducing fossil fuel dependency. Second, it takes advantage of the photocatalytic properties of materials to decompose organic matter during water treatment, thus minimizing the usage of chemical reagents. Applications comprise wastewater power generation, seawater desalination and organic matter degradation.

The generation of reactive species and their derivatives, whether in the human body or in the food systems, contributes to various human diseases and compromises food quality. Unfortunately, both natural and synthetic antioxidants have specific limitations. Green chemistry-derived carbon dots offer a promising solution in this regard. Here we review the antioxidant activity of green synthesized carbon dots. The review commences with an overview of carbon dots, their properties, and the top-down and bottom-up synthesis approaches, along with their merits and drawbacks. Furthermore, the importance of the green chemistry concept is highlighted. The role of different functional groups in carbon dots attributed to their antioxidant activity is emphasized. Subsequently, the review elucidates several methods commonly utilized to evaluate the antioxidant activity of carbon dots together with a discussion on various oxidative and non-oxidative stress markers. The review compiles a variety of ex vivo, in vitro, and in vivo studies underscoring the antioxidant activity of pristine and doped carbon dots. Among all studies, the hydrothermal method was observed to be a popular synthesis approach. Out of 87 studies, 38 exclusively assessed the 2,2-diphenyl-1-picrylhydrazyl-scavenging properties of pristine and doped carbon dots with half-maximum effective concentration values ranging from 2.7 to 524 μg mL⁻¹. The subsequent studies recorded the scavenging of other radicals alongside 2,2-diphenyl-1-picrylhydrazyl, with 18, 14, 10, 5, and 2 studies demonstrating the scavenging efficacy of carbon dots for hydroxyl, 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid), superoxide, hydrogen peroxide, and nitric oxide radicals, respectively. Furthermore, 18 studies reported the antioxidant property of carbon dots in cell, animal, and vertebrate models by modulating oxidative stress markers and upregulating the expressions of various antioxidant enzymes. The review also highlights the prooxidant nature of green carbon dots briefly. Finally, the paper delves into the practical applications of carbon dots in the food, agricultural, and environmental sectors.

Microplastic pollution in aquatic environments has emerged as a significant environmental concern, posing risks to ecosystems and human health. Urban stormwater runoff has been identified as a major source of microplastics, with microplastic concentrations reaching up to six times higher than those in wastewater treatment plant effluents. Given the increasing urbanization and inadequate waste management, effective mitigation strategies are urgently needed to prevent the discharge of microplastics into natural water systems. Green infrastructure, designed for sustainable stormwater management, has gained attention as a promising approach to reducing microplastic pollution while providing additional environmental benefits. Here, we review various green infrastructure technologies, including bioretention systems, permeable pavements, stormwater ponds, and constructed wetlands, focusing on their effectiveness in microplastic mitigation. Bioretention systems exhibit removal efficiencies ranging from 80% to over 99%, and are particularly effective for particles sized 20 μm or above. Constructed wetlands achieve removal rates between 28 and 75%, effectively treating microplastics in the 100–500 μm range. Permeable pavements demonstrate removal efficiencies of 89–96.6%, especially for particles less than 100 μm. Retention ponds retain 55–98% of microplastics, with sediment retention reaching up to 85%. We found that the performance of these systems is influenced by soil amendments, vegetation, and adsorption-based mechanisms such as biochar applications, which can enhance removal to over 99% under optimized conditions. Phytoremediation with aquatic plants such as Lemna minor achieves a 76% removal rate, while biofilm-based strategies offer slower but potentially sustainable solutions. This review highlights the necessity of integrating multiple green infrastructure approaches to optimize microplastic removal.

The construction industry, being responsible for a large share of global carbon emissions, needs to reduce its high carbon output to meet carbon reduction goals. Artificial intelligence can provide efficient support for carbon emission calculation and prediction. Here, we review the use of artificial intelligence techniques in forecasting, management and real-time monitoring of carbon emissions, focusing on how they are applied, their impacts, and challenges. Compared to traditional methods, the prediction accuracy of artificial intelligence models has increased by 20%. Artificial intelligence-driven systems could reduce carbon emissions by up to 15% through real-time monitoring and adaptive management strategies. Artificial intelligence applications improve energy efficiency in buildings by up to 25%, while reducing operational costs by up to 10%. Artificial intelligence supports the establishment of a digital carbon management system and contributes to the development of the carbon trading market.

Sulfur dioxide pollution by ship emissions can be efficiently decreased by using exhaust gas scrubbers, yet particles can pass through the scrubber and be released into the atmosphere. Here, we studied the impact of using a wet scrubber on the composition of particle emissions, by single-particle analysis. At low engine loads, results show no significant changes in particle composition of metals, salts, and polycyclic aromatic hydrocarbons (PAH). At high engine loads, the scrubber reduced soot and PAH signatures about fourfold. Particles passing through the scrubber undergo minimal chemical changes, except for sulfate uptake. The cleaning effect of wet scrubbers is attributed to the removal of water-soluble gas-phase compounds, diffusion-dominated uptake of ultrafine particles, and wet deposition of coarse particles. The scrubber has little effect on reducing the health and environmental impacts of the remaining particles that pass through it. These emitted particles, primarily in the 60–200 nm size range, constitute a significant portion of the inhalable particle mass and have the potential for long-range transport.

Classical production of construction particleboards with high-grade wood and formaldehyde-based binders induces forest depletion and pollution, calling for alternatives. Here, we designed in situ lignin bonding to transform low-grade woods into high-performance and formaldehyde-free particleboards. This method involves the deconstruction of fine wood particles to soften cell walls, eliminating undesirable water-soluble components while preserving lignin, followed by a thermo-compression molding procedure to facilitate the formation of a compact and cross-linked structure within softened wood particles. Results show that particleboard displays high mechanical strength with a rupture modulus of 66.7 MPa and excellent water resistance with a thickness swelling of 2.1%. The performance of particleboards is enhanced by low wood hardness, small particle size, removal of water-soluble fractions, and preservation of lignin. The self-adhesion technique is straightforward, practical, and scalable.

Nanoplastics are emerging contaminants which can induce intestinal inflammation and dysfunction, yet their possible influence on colorectal tumorigenesis remains unclear. Here, six‑week‑old male mice were exposed to 125 mg/L 80 nm polyethylene nanoplastics, polyethylene nanoplastic/azoxymethane, polyethylene nanoplastics/azoxymethane/dextran sulfate sodium, and controls for 66 days. We assessed intestinal symptoms, colorectal tumorigenesis, and pathological, ultrastructural and molecular changes. Results show more colon tumors, of 18.3 versus 13.5, and heavier tumor burdens, of 113.1 versus 67.7 mm² in the mice treated with nanoplastics/azoxymethane/dextran sulfate sodium. Similarly, there were more colon tumors, of 6.0 versus 2.2, and heavier tumor burdens, of 26.0 versus 7.0 mm² in mice treated with nanoplastics/azoxymethane. Mice treated with nanoplastics alone developed colorectal neoplasms, of 2.9, with tumor burdens of 10.6 mm² and a pathology of polyp. Exposure to nanoplastics promoted tumor‑associated macrophages infiltration; disrupted microvilli, intercellular junctions, and the mitochondrial structures of colonic epithelium; and activated inflammation‑associated signaling pathways. Overall, the exposure to polyethylene nanoplastics facilitates the initiation and promotion of colorectal tumorigenesis, possibly by affecting mitochondrial structure and aggravating chronic colitis.