Fine particulate matter (PM₂.₅) has attracted extensive attention because of its baneful influence on human health and the environment. However, the sparse distribution of PM₂.₅ measuring stations limits its application to public utility and scientific research, which can be remedied by satellite observations. Therefore, we developed a Geo-intelligent long short-term network (Geoi-LSTM) to estimate hourly ground-level PM₂.₅ concentrations in 2017 in Wuhan Urban Agglomeration (WUA). We conducted contrast experiments to verify the effectiveness of our model and explored the optimal modeling strategy. It turned out that Geoi-LSTM with TOA reflectance, meteorological conditions, and NDVI as inputs performs best. The station-based cross-validation R², root mean squared error and mean absolute error are 0.82, 15.44 μg/m³, 10.63 μg/m³, respectively. Based on model results, we revealed spatiotemporal characteristics of PM₂.₅ in WUA. Generally speaking, during the day, PM₂.₅ concentration remained stable at a relatively high level in the morning and decreased continuously in the afternoon. While during the year, PM₂.₅ concentrations were highest in winter, lowest in summer, and in-between in spring and autumn. Combined with meteorological conditions, we further analyzed the whole process of a PM₂.₅ pollution event. Finally, we discussed the loss in removing clouds-covered pixels and compared our model with several popular models. Overall, our results can reflect hourly PM₂.₅ concentrations seamlessly and accurately with a spatial resolution of 5 km, which benefits PM₂.₅ exposure evaluations and policy regulations.

High particulate matter (PM) and ozone (O₃) concentration in Hong Kong are frequently observed during the summertime typhoon season. Despite the critical effect of a typhoon on air pollution, contributions of vertical wind profile and cloud movement during transboundary air pollution (TAP) on surface PM and O₃ concentration have yet to be fully understood. This work is the first study to apply a network of Doppler light detection and ranging (LiDAR) as well as back trajectory analysis to comprehensively analyze the effect of a weak Typhoon (Danas) occurring during 16–19 July 2019 on different variations in PM and O₃ concentration. During the typhoon Danas, three types of surface air pollution with five episodes were identified: (1) low PM and high O₃ concentration; (2) co-occurring high PM and O₃ concentration and (3) high PM and low O₃ concentration. Employing our 3D Real-Time Atmospheric Monitoring System (3DREAMs) along with surface observations, we found the important role of TAP in the increases in surface PM and O₃ concentration with significant vertical wind shear that transported air pollutants at upper levels, and strong vertical mixing that brought air pollutants to the ground level. Cloud movement related to typhoon periphery, as well as high solar radiation due to sinking motion and remote transport by continental wind, have an impact on local O₃ concentration. For the substantial difference in O₃ concentration between two air quality measurement sites, the similar vertical aerosol distributions and wind profiles suggest the comparable TAP contributions at the two sites and thus infer the critical role of local O₃ photochemical process in the O₃ difference. This work comprehensively reveals the influences of a weak typhoon on variations in PM and O₃ during the five episodes, providing important references for air quality monitoring and forecast in regions under the influence of typhoon.

PM₂.₅ pollution was associated with numerous adverse health effects. However, PM₂.₅ induced toxic effects and the relationships with toxic components remain largely unknown. To evaluate the metabolic toxicity of PM₂.₅ at environmentally relevant doses, investigate the seasonal variation of PM₂.₅ induced toxicity and the relationship with toxic components, a combination of general pathophysiological tests and metabolomics analysis was conducted in this study to explore the response of SD rats to PM₂.₅ exposure. The result of general toxicology analysis revealed unconspicuous toxicity of PM₂.₅ under environmental dose, but winter PM₂.₅ at high dose caused severe histopathological damage to lung. Metabolomic analysis highlighted significant metabolic disorder induced by PM₂.₅ even at environmentally relevant doses. Lipid metabolism and GSH metabolism were primarily influenced by PM₂.₅ exposure due to the high levels of heavy metals. In addition, high levels of organic compounds such as PAHs, PCBs and PCDD/Fs in winter PM₂.₅ bring multiple overlaps on the toxic pathways, resulting in larger pulmonary toxicity and metabolic toxicity in rats than summer.

Phosphorus (P) cycling present in sediments associated with iron (Fe), manganese (Mn) and sulfur (S) geochemical processes may cause secondary pollution in overlying water. Understanding the mechanisms of P release from sediments should help to restore water quality. This study used the diffusive gradients in thin film (DGT) technique to investigate the seasonal variation in the lability, remobilization mechanisms, and release characteristics of sediment P in the uncontaminated Xizhi River and the severely contaminated Danshui River, South China. P accumulation in sediments contributed to higher DGT-labile P concentrations in contaminated reaches, and the highest labile P concentrations were generally observed in summer season at each site. The significant positive relationships (p < 0.05) between labile Fe and P confirmed the Fe–P coupling release mechanism in uncontaminated sediments. Stronger relationships between labile Mn and P at contaminated sites indicated that Mn oxides played an important role in P remobilization. However, sulfate reduction associated with microbial activities (crucial genera: Desulfobulbus, Desulfomicrobium and Desulforhabdus) was considered to decouple the Fe & Mn–P cycling relationship, promoting P release at contaminated sites. The effluxes of sediment P were much higher in the Danshui River (mean 0.132 mg cm⁻²·d⁻¹) than in the Xizhi River (mean 0.038 mg cm⁻²·d⁻¹). And hot season led to growth in P effluxes that was much greater in contaminated river.

Daunting amounts of microplastics are present in surface waters worldwide. A main category of microplastics is synthetic microfibers, which originate from textiles. These microplastics are generated and released in laundering and are discharged by wastewater treatment plants or enter surface waters from other sources. The polymers that constitute many common synthetic microfibers are mostly denser than water, and eventually settle out in aquatic environments. The interaction of these microfibers with submerged aquatic vegetation has not been thoroughly investigated but is potentially an important aquatic sink in surface waters. In the Laurentian Great Lakes, prolific growth of macrophytic Cladophora creates submerged biomass with a large amount of surface area and the potential to collect and concentrate microplastics. To determine the number of synthetic microfibers in Great Lakes Cladophora, samples were collected from Lakes Erie and Michigan at multiple depths in the spring and summer of 2018. After rinsing and processing the algae, associated synthetic microfibers were quantified. The average loads of synthetic microfibers determined from the Lake Erie and Lake Michigan samples were 32,000 per kg (dry weight (dw)) and 34,000 per kg (dw), respectively, 2–4 orders of magnitude greater than loads previously reported in water and sediment. To further explore this sequestration of microplastics, fresh and aged Cladophora were mixed with aqueous mixtures of microfibers or microplastic in the laboratory to simulate pollution events. Microscopic analyses indicated that fresh Cladophora algae readily interacted with microplastics via adsorptive forces and physical entanglement. These interactions mostly cease upon algal senescence, with an expected release of microplastics in benthic sediments. Collectively, these findings suggest that synthetic microfibers are widespread in Cladophora algae and the affinity between microplastics and Cladophora may offer insights for removing microplastic pollution.Macroalgae in the Laurentian Great Lakes contain high loads of synthetic microfibers, both entangled and adsorbed, which likely account for an important fraction of microplastics in these surface waters.

In general, tire tread rubber compounds contain oleamide for improvement of manufacturing processibility, mold release characterization, and abrasion resistance. Tire tread wear particles (TWPs) are one of major contributors to microplastic emissions. In this study, a novel analytical method for quantification of TWP in microparticles produced on the road (road dust, MPRs) was developed by employing oleamide as a new marker. MPRs were collected at bus stops in autumn, winter, and summer seasons. MPRs of 38–63, 63–106, 106–212, and 212–500 μm obtained by size separation were employed for the analysis. Rubber components for bus and passenger car tire tread compounds were identified using pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). Oleamide was extracted from the MPRs with acetone and was identified using GC/MS. The oleamide concentration was analyzed using GC equipped with flame ionization detector (FID). The TWP contents of the MPRs were determined using the oleamide concentrations and the reference compound formulations. In order to reduce the sampling errors, each experiment was carried out five times and the results were averaged. The TWP contents of the MPRs were 1.4–4.7 wt% and were different according to the sampling seasons and places. The TWP contents were increased by increasing the traffic volume and the temperature.

Phthalate pollution in soil and vegetables in plastic agricultural greenhouses has attracted wide concern. Investigating airborne phthalates in this environment can improve understanding of air-soil or air-vegetable phthalate migration. However, studies of phthalates in plastic agricultural greenhouse air are rare. To fill this gap, 25 gas-phase and 23 particle-phase samples were collected from 12 typical plastic greenhouses in Shaanxi. 16 types of phthalates were measured by a gas chromatography-mass spectrometry system (GC-MS) to analyse their pollution features and variations. Results showed that in the air of the plastic greenhouses, the median concentration of the sum of sixteen type phthalates (∑₁₆ phthalates) was 5305 ng m⁻³, with 5th-95th value of 1214–9616 ng m⁻³. Phthalates in gas-phase samples were over 100 times higher than the levels in particle-phase samples. Air phthalate concentrations in the plastic greenhouses were higher than those in the control groups (P < 0.05). Air bis (2-ethylhexyl) phthalate (DEHP) and di-n-butyl phthalate (DnBP) accounted for 66.9% and 29.3% of total ∑₁₆ phthalate concentrations, respectively. Air phthalate concentrations in the plastic greenhouses in winter were 1.1–5.3 times higher than the levels in summer respectively (P < 0.05). Gas-particle partition coefficients (KP) values of DEHP in summer (median of 1.52 × 10⁻⁴ m³ μg⁻¹) were higher than KP values of DnBP in summer (0.60 × 10⁻⁴ m³ μg⁻¹). Log-transformed KP values of DnBP and DEHP were linear correlated to the reciprocal of air temperatures, respectively (P < 0.05).

Black carbon (BC) is the most important aerosol light-absorbing component, and its effect on radiation forcing is determined by its microphysical properties. In this study, two microphysical parameters of refractory BC (rBC), namely, size distribution and mixing state, in urban Beijing from 2013 to 2019 were investigated to understand the effects of source changes over the past years. The mass equivalent diameter of rBC (Dc) exhibited bimodal lognormal distributions in all seasons, with the major modes accounting for most (>85%) of the rBC masses. The mass median diameter (MMD) was obviously larger in winter (209 nm) than in summer (167 nm) likely due to the contribution of more rBC with larger Dc from solid fuel combustion and enhanced coagulation of rBC in polluted winter. More rBC particles were thickly coated in winter, with the number fraction of thickly coated rBC (fcₒₐₜBC) ranging within 29%–48% compared with that of 12%–14% in summer. However, no evidential increase in BC light-absorption capability was observed in winter. This finding was likely related to the lower absorption efficiency of larger rBC in winter, which partly offset the coating-induced light enhancement. Two stage of decreases in MMD and fcₒₐₜBC were observed, accompanied with a persistent decrease in rBC loading, thereby reflecting the discrepant effects of source control measures on rBC loading and physical properties. The control measures in the earlier stage before 2016 was more efficient to reduce the rBC loading but slightly influenced the microphysical properties of rBC. As of 2016, the reduction in rBC concentration slowed down because of its low atmospheric loading. However, rBC showed a more obvious decrease in its core size and became less coated. The decrease in fcₒₐₜBC may have weakened the BC absorption and accelerated the decrease in light absorption resulting from the reduction in rBC loading.

140 contaminants belonging to various classes (organochlorine and organophosphorus pesticides, pyrethroid insecticides, carbamates, fungicides, acaricides, herbicides, synergists, insect growth regulators, polychlorobiphenyls, polycyclic aromatic hydrocarbons) were simultaneously analysed by GC-MS/MS in marine sediments, aquatic plant leaves and fish tissues samples. A total of 260 samples from five stations along the coast of Tunisia were evaluated. The results highlight that only 28 residues (12 polychlorobiphenyls, 8 organochlorine pesticides, 7 polycyclic aromatic hydrocarbons and triphenyl phosphate) were detected at levels higher than relative LOQ values. The amounts in sediment samples were compared with Sediment Quality Guidelines (SQGs) showing that the values are acceptable and no toxic effect is expected on aquatic organisms. A little variation of contaminant residues in sediment samples among coastal stations was recorded. Namely, with respect to almost all polychlorobiphenyls and organochlorine pesticides, higher values were recorder in summer. With respect to almost all polycyclic aromatic hydrocarbons, higher values were recorder in autumn. Aquatic plant leaves showed a residue accumulation higher than that of other compartments of marine system. The data about fish samples (Sparus aurata and Sarpa salpa, the two most frequently caught fish species at five sites on the central coast of Tunisia) do not pose direct hazard to human health because values were lower than protection limits.

As filter feeders, bivalve mollusks have a high potential risk of contamination by microplastics (MPs), which can be considered a transfer vector for humans through their consumption. Spatial-temporal differences in the MP concentration were evaluated in the cultured oyster Magallana gigas in Todos Santos Bay (TSB) and San Quintin Bay (SQB) during winter and summer (2019). MPs were found in all samples in both seasons, where microfibers were the most abundant particles observed. Only in winter, statistically significant differences were observed in the average concentration of ingested MPs between oysters from TSB and SQB. In each bay, the highest concentrations were observed during winter. Seasonal differences between MP concentrations were only found in TSB. During summer, the content of MPs was compared between the digestive system and the rest of the soft tissue in organisms from each site, and statistically significant differences were not observed, except by one site in SQB. Polymers were identified via μ-FTIR-ATR spectrometry. Polyester, polyacrylonitrile, and rayon were the most common plastics detected. However, due to the low concentration of MPs found in oysters, its consumption does not represent a risk to human health. Moreover, MP concentrations in organisms appear to respond to variables, such as temporality and the water circulation dynamics within the bays.