Environmental Science & Technology Letters Environ.最新文献

A limited understanding of urban methane (CH₄) emissions in China challenges the evaluation of the coal-to-gas switch toward carbon neutrality by 2060. CH₄ flux was measured in urban Beijing using the eddy covariance method during a summer campaign. With a mean of 152.6 ± 107.9 nmol/m²/s, the CH₄ flux was estimated to depend little on the intensity of human activities, with minimal influence from biogenic sources. Emission hotspots with large temporal variability were identified in the study fetch area, which increased the mean CH₄ flux by 12.5%. Based on the lack of large, known biogenic sources in nonhotspot (background) areas, we attributed the CH₄ flux in these areas (135.6 ± 70.56 nmol/m²/s) mainly to natural gas. Thus, we estimate as an upper limit that natural gas contributes 88.9% to the total CH₄ flux in urban Beijing. However, poor alignment between the dominant sources in the inventories and the characteristics of the measured CH₄ flux were observed, suggesting substantial underestimation of emissions from natural gas sources in the inventories. A leakage ratio of 1.4% (0.7–2.1%) of consumed natural gas was determined in Beijing. Pinpointing emissions with more granular methods could improve our understanding of the urban CH₄ source profile in Beijing.

p-Phenylenediamines (PPDs) are emerging pollutants in the environment due to their extensive application in rubber-related products, yet their potential indoor exposure has been largely overlooked. This study investigated the occurrence characteristics of PPDs and their oxidative products (PPD-Qs) in dust from indoor, i.e., auto repair workshops, hardware malls, and home furnishings markets, as well as outdoor environments, i.e., highway and motorway intersections, revealed the influencing factors for transformation, and assessed associated exposure risks. The presence of PPDs and PPD-Qs in specific indoor environments has been documented. Particularly high levels of these compounds were observed in dust from auto repair workshops (median: 1.68 × 10³ ng/g (PPDs) and 421 ng/g (PPD-Qs). The indicator monomers for PPDs and PPD-Qs emitted from different sources were identified. Furthermore, through concentration analysis and theoretical calculations, the transformation from PPDs to PPD-Qs was revealed to be influenced by the total organic carbon and transition metals present in the dust with Fe³⁺ and Cu²⁺ acting as the most effective catalysts. Finally, occupational populations in environments such as auto repair workshops were found to face extremely high exposure levels. This study emphasizes the need to recognize and address the risks associated with these compounds indoors.

Understanding historical chemical usage is crucial for assessing current and past impacts on human health and the environment and for informing future regulatory decisions. However, past monitoring data are often limited in scope and number of chemicals, while suitable sample types are not always available for remeasurement. Data-driven cheminformatics methods for patent and literature data offer several opportunities to fill this gap. The chemical stripes were developed as an interactive, open source tool for visualizing patent and literature trends over time, inspired by the global warming and biodiversity stripes. This paper details the underlying code and data sets behind the visualization, with a major focus on the patent data sourced from PubChem, including patent origins, uses, and countries. Overall trends and specific examples are investigated in greater detail to explore both the promise and caveats that such data offer in assessing the trends and patterns of chemical patents over time and across different geographic regions. Despite a number of potential artifacts associated with patent data extraction, the integration of cheminformatics, statistical analysis, and data visualization tools can help generate valuable insights that can both illuminate the chemical past and potentially serve toward an early warning system for the future.

Recent studies have suggested that particulate nitrate (NO₃^–) photolysis could be an important source of atmospheric oxidants, and one of its main products, N(III), contributes to the heterogeneous formation of sulfate (SO₄^2–) in aerosol water─a potential missing source of SO₄^2– in polluted environments. However, its effects on SO₄^2–and air quality in different regions remain unexplored. In this study, we implement a detailed model representation of SO₄^2– formation via NO₃^– photolysis into the global chemical transport model GEOS-Chem. Our results find considerable impacts of NO₃^– photolysis on surface SO₄^2–, especially over India and other coastal regions (up to 15% increment of annual average concentrations), which were previously unaccounted for in most models. The effects are mainly due to S(IV) oxidation by OH, H₂O₂, and O₃ following renoxification, which outcompetes aqueous oxidation by N(III), contrary to previous laboratory and modeling studies. Further analysis suggests that past studies might have underestimated the particle-to-gas transfer of N(III) in ambient aerosols. We suggest that future modeling works should use experiment-derived parameters with caution and a thorough understanding of the mechanism before implementing them into models, especially when dealing with those from large particles or bulk solutions involving mass transfer.

Di-2-ethylhexyl phthalate (DEHP), an endocrine-disrupting plasticizer, may interfere with insulin signaling and increase diabetes risk at low concentrations. Predominantly ingested through food, DEHP directly impacts the intestines where gut hormones that regulate blood sugar are produced. Colonic organoids, with their realistic three-dimensional structure, provide a more physiologically relevant model. Our study used mouse colonic organoids to investigate dietary DEHP exposure on gut endocrine function. Results showed that low doses of DEHP promoted secretion of glucagon-like peptide-1 (GLP-1), peptide YY (PYY), and gastric inhibitory polypeptide (GIP), while decreasing cholecystokinin (CCK) secretion. DEHP exposure increased cyclic AMP levels, supporting the secretion of GLP-1, PYY, and GIP, which may enhance insulin secretion. Metabolomic analyses indicated decreased arachidonic acid levels, potentially increasing inflammation risk and inhibiting gallbladder contraction. These results suggest DEHP exposure significantly alters gut hormone secretion and metabolism, disrupting glucose regulation. Further research is needed to fully understand these mechanisms and their implications for diabetes risk.

The sea surface microlayer (SML) is the thin interface between the ocean and the atmosphere, exhibiting an enrichment of hydrophobic and surfactant-like chemicals. Here we report the concentrations of organophosphate esters (OPEs), widely used flame retardants and plasticizers, in the SML and underlying waters from a north–south transect in the Atlantic and Southern Oceans. Generally, concentrations of OPEs in the SML were higher than in the underlying waters. Concentrations in the SML were correlated with the chlorophyll α content for some OPEs, consistent with biogenic surfactants at the SML. The enrichment factors (ratio of concentrations in SML over concentrations in underlying waters) were 5.84 ± 8.97 and 9.10 ± 9.48 for the Atlantic and Southern Oceans, respectively. The average enrichment factors in sea spray aerosols (SSA), estimated using previously reported aerosol-phase concentrations, ranged from 3.69 × 10⁴ to 3.33 × 10⁶. These OPE enrichments in SSA are high and suggest that the formation of SSA, mediated by the enrichment in the SML, could be relevant for many semivolatile organic pollutants. Future research is needed to elucidate the variables driving the enrichment in the SML, its large variability, as well as its role in the fate of organic pollutants.

Tris(2,4-di-tert-butylphenyl) phosphite (AO168) is a widely utilized organophosphite antioxidant in the field of plastics. Throughout the production and usage processes, AO168 can undergo oxidation and convert into tris(2,4-di-tert-butylphenyl) phosphate (AO168═O), which has been identified as one of the novel organophosphate esters (OPEs). AO168═O is now extensively present in the environment, with concentrations generally exceeding those of traditional OPEs such as triphenyl phosphate and tri(2-chloroisopropyl) phosphate. Consequently, AO168═O has emerged as a significant concern that is receiving attention from the scientific community. However, there exists some controversy regarding the formation mechanisms and potential risks of AO168═O. This Review provides a comprehensive overview for the first time of the environmental occurrence, formation pathways, toxicities, and risks linked to AO168═O, aiming to assist researchers and policymakers in obtaining an unbiased description of its potential impacts on both the environment and human health. Given numerous unresolved aspects surrounding AO168═O along with its wide occurrence, greater attention should be devoted to this emerging contaminant.