This study presents the first comprehensive field-based quantification of methane emissions from the Aradkouh Solid Waste Processing and Disposal Complex in Tehran, which NASA has recognized as a global super-emitter. Using an integrated approach that combines field measurements and model simulations, methane emissions were quantified through direct surface flux measurements, well and crack sampling, and modeling using LandGEM and IPCC methods. Over 159 sampling points were monitored between June 2023 and March 2024 using static flux chambers and gas chromatography, resulting in spatially resolved methane flux estimates. Total methane emissions were 206.79 tons/day (288,786 m3/day), where 91.7% of them came from active landfill areas. Direct measurements recorded notably higher fluxes in recently active sections, with peak surface fluxes reaching 4,740 g m-2 day-1. Comparative modeling indicated that the IPCC First-Order Decay (FOD) method produced estimates very close to field measurements (relative error: 1.87%). In contrast, LandGEM overestimated emissions by nearly two times due to sensitivity to parameters and non-site-specific defaults. A thorough comparison with national and international studies revealed that local waste composition, operational history, and climate conditions greatly impact methane generation emission. The study also points to existing landfill engineering issues, including poor gas collection and poor data management, as key barriers to effective mitigation. To address these gaps and promote sustainable waste management practices, the Aradkouh complex should properly implement engineered landfills, online waste tracking, and enhanced control procedures instead of relying on a controlled landfill.
The land aerosol optical depth (AOD) based on the Advanced Geostationary Radiation Imager (AGRI) aboard Fengyun-4B (FY-4B) has been officially released since August 2022. The initial operational product was based on the Dark Target (DT) algorithm and has been previously evaluated. A new land AOD product was subsequently developed under an improved Deep Blue (DB) framework with an hourly surface reflectance prior database, broadly consistent with the retrieval approaches of the Advanced Himawari Imager (AHI) aboard Himawari-9 and the Geostationary Environment Monitoring Spectrometer (GEMS) aboard GK-2B, this study evaluates the FY-4B/AGRI DB-based AOD and compares with the AHI and GEMS products. Results show that the AGRI AOD achieves the highest accuracy (R=0.840, RMSE=0.175) relative to AHI (R=0.765, RMSE=0.217) and GEMS (R=0.707, RMSE=0.214), with 57.66% within the Expected Error envelope (EE=±(0.05+0.20τ)), ranking between AHI (56.19%) and GEMS (59.38%). The AGRI AOD maintains relatively stable retrieval errors across different vegetation-index ranges, where the accuracy of AHI and GEMS is limited. In terms of geometric sensitivity, the AGRI AOD degrades at viewing zenith angles above 56°, while AHI errors increase markedly when SZA is below 15°, and GEMS shows larger variability. These findings confirm the competitive accuracy of the FY-4B DB-based AOD on the international stage and provide quantitative guidance for future multi-satellite aerosol product fusion.
To explore the atmospheric ozone (O3) photochemistry in the Pearl River Estuary (PRE), parallel observations of volatile organic compounds (VOCs) and O3 were conducted at two contrasting sites: a coastal site (HKUST, eastern PRE) and a marine site (WS, southwestern PRE), from November to December 2021. Both sites exhibited similar VOC compositions dominated by oxygenated VOCs (OVOCs, 78%-82%), while lower total concentrations were observed at WS site. An observation-based box model analysis further revealed higher daytime atmospheric oxidation capacity (AOC), greater VOC-driven OH reactivity, slightly higher peak production rates of OH, HO2, and alkyl peroxy (RO2) radicals at the HKUST site. The dominant pathways for OH, HO2, and RO2 formation at both sites were HO2 + NO, RO2 + NO and VOCs +OH, respectively, with VOCs involved reactions, such as VOCs + OH and OVOCs photolysis, contributed more significantly to ROx radicals at the HKUST site. Paradoxically, higher O3 concentrations were observed at the WS site, despite its lower daytime net O3 production rate. Backward trajectory analysis attributed these O3 episodes to continental outflows from eastern Guangdong passing through Hong Kong, where abundance background O3 and photochemical processing during transport amplified O3 pollution. This study deepens our comprehension of surface photochemical O3 formation mechanism in coastal/marine environments and highlights the critical role of regional transport in exacerbating O3 pollution in the Pearl River Estuary.
Background Evidence on how long-term exposure to multiple air pollutants contributes to the onset and progression of cardio-renal-metabolic disease (CRMD), including cardiovascular disease (CVD), type 2 diabetes (T2D) and chronic kidney disease (CKD), remains limited. We aimed to clarify these associations and further explore the potential biological intermediary role of low-grade inflammation. Methods 369,168 UK Biobank participants were included to evaluate associations of individual pollutants and their mixtures with CRMD onset and progression. Joint effects were assessed via quantile g-computation. An inflammation score (INFLA score) was constructed for mediation analyses, with multivariable models adjusted for demographic, socioeconomic, and lifestyle factors. Results During a median 13.6 years of follow-up, 76,871 participants developed a first CRMD (FCRMD), of whom 12,851 subsequently progressed to cardio-renal-metabolic multimorbidity (CRMM). Compared with the lowest quartile, participants in the highest PM2.5 quartile exhibited higher hazards of FCRMD (HR: 1.09, 95% CI: 1.06-1.11) and CRMM (1.22, 1.15-1.29). In multi-state models, each quartile increase in pollutant mixtures was associated with HRs (95% CI) of 1.02 (1.01, 1.03) for baseline to FCRMD and 1.04 (1.01, 1.06) for FCRMD to CRMM, with PM2.5 exhibiting the largest positive relative weight. Disease-specific analyses revealed heightened vulnerability along pathways involving CKD. INFLA score accounted for the associations between PM2.5 and CRMD with subtle mediated proportion, driven primarily by C-reactive protein. Stratified analyses demonstrated stronger hazard elevations among individuals with unfavorable baseline lifestyle profiles. Conclusions Long-term exposure to multiple air pollutants was associated with elevated hazards of CRMD onset and trajectory progression, particularly for pathways involving kidney damage. These longitudinal associations may be partially accounted for by systemic low-grade inflammation, with adherence to healthy lifestyles mitigating environmental vulnerability.
Atmospheric dry deposition is a crucial process influencing the fate of polycyclic aromatic hydrocarbons (PAHs) and their derivatives. Seasonal variations in deposition reflect changes in the environmental behaviour and sources of these compounds over time. This study investigated the occurrence and dry deposition fluxes of PAH and their derivatives in atmospheric particulate samples collected on Beihuangcheng Island (BHC) in the central Bohai Sea in August and October 2019 and February and May 2020. The study focused on 16 priority PAHs designated by the United States Environmental Protection Agency (Σ16PAHs), 12 alky-PAHs (Σ12A-PAHs), and 25 nitro-PAHs (Σ25N-PAHs). We calculated the dry deposition velocities of PAHs and their derivatives using an improved Slinn model, which accounted for the significant variations among particles of different sizes. The results revealed that the annual average concentrations of Σ16PAHs, Σ12A-PAHs, and Σ25N-PAHs were 2.5 ± 2.4 ng m−3, 0.4 ± 0.2 ng m−3, and 0.09 ± 0.08 ng m−3, respectively. In summer, 2- and 3-ring compounds dominated Σ16PAHs, Σ12A-PAHs, and Σ25N-PAHs. In contrast, 4-, 5-, and 6-ring compounds were more prevalent in winter. Oil combustion was identified as the main source of PAHs and their derivatives in the atmosphere at BHC. These compounds were mainly associated with fine particles in the <0.65 μm and 0.65–1.1 μm size ranges. The dry deposition fluxes of PAHs and their derivatives were estimated using the observational data and a typical dry deposition model. The annual average dry deposition fluxes of Σ16PAHs, Σ12A-PAHs, and Σ25N-PAHs were 75.37 ± 45.08 μg m−2 yr−1, 20.88 ± 8.29 μg m−2 yr−1, and 3.58 ± 1.61 μg m−2 yr−1, respectively. This study provides new insights into the environmental fate of PAHs and their derivatives and valuable guidance for developing effective measures to protect marine ecosystem health.
