This paper aims to identify the atmospheric boundary layer turbulence structure and its effect on severe foggy haze events frequently occurring in Northern China. We use data collected from a ground eddy covariance system, meteorology tower, and a PM₂.₅ collector in Baoding, China during December 2016. The data shows that 73.5% of PM₂.₅ concentration is greater than 100 μg m⁻³ with a maximum of 522 μg m⁻³. Analyses on vertical turbulence spectrum also reveal that 1) during the pollution period, lower wind can suppress large-scale turbulence eddies, which are more likely inhomogeneous, breaking into small-scale eddies, and 2) the air pollutant scattering effect for radiation could decrease the air temperature near the ground and generate weak vertical turbulence during the daytime. At night, air pollutants suppress the land surface cooling and decrease the air temperature difference as well as the vertical turbulence intensity difference. The vertical turbulence impact analysis reveals that the percentage of large-scale turbulence eddies can also change the atmospheric vertical mixing capacity. During the daytime, the air pollution evolution is controlled by the wind speed and vertical turbulence intensity. While at night, the vertical turbulence is weak and the atmospheric vertical mixing capacity is mainly controlled by the large-scale eddies’ percentage. The increased number of large-scale turbulence eddies led by low wind at night could increase the vertical mixing of air pollutants and decrease its concentration near the ground.

A typical two-day start-up of municipal solid waste incinerators (MSWIs) can yield polychlorinated dibenzo-p-dioxin and dibenzofuran (PCDD/F) and polychlorinated biphenyl (PCB) emission quantities around 10 times higher than those from an entire year of normal operations, as measured in this study. Thus, we tested specific control strategies for inhibiting the formation of chlorinated persistent organic pollutants (Cl-POPs), namely, extensively cleaning the ash accumulated beneath the furnace bed of the combustion chamber and deposited on the walls of the superheater and economizer and shortening the residence time of the flue gas in the optimal temperature window for Cl-POP formation. Also, we advanced the injection times of the activated carbon and lime slurry to lower Cl-POP emissions during start-up. Our findings show that these strategies were highly effective and reduced the Cl-POP emissions by > 98%, most of which (96.4–98.2%) was attributable to inhibiting formation. In summary, the proposed control strategies require no modifications to existing air pollution control devices, have little influence on operational cost, and are effective and feasible for the majority of MSWIs.

Staotcysts, the mechanosensory organs common to many marine invertebrates, have shown sensitivity to aquatic noise. Previously, rock lobsters (Jasus edwardsii) from a remote site with little exposure to anthropogenic noise incurred persistent damage to the statocyst and righting reflex following exposure to seismic air gun signals. Here, J. edwardsii collected from a site subject to high levels of anthropogenic noise were exposed to an equivalent seismic air gun signal regime as the previous study of noise-naïve lobsters. Following exposure, both control and exposed treatments were found to have damage to the statocyst equivalent to that of noise-naïve lobsters following seismic exposure, which led to the conclusion that the damage was pre-existing and not exacerbated by seismic exposure. The source of the damage in the lobsters in this study could not be ascertained, but the soundscape comparisons of the collection sites showed that the noisy site had a 5–10 dB greater level of noise, equivalent to a 3–10 times greater intensity, in the 10–700 Hz range than was found at the remote collection site. In addition to the lack of further damage following seismic exposure, no disruption to the righting reflex was observed. Indeed, compared to the noise naïve lobsters, the lobsters here demonstrated an ability to cope with or adapt to the mechanosensory damage, indicating a need for better understanding of the ecological impacts of the damage caused by low frequency noise on marine organisms. More broadly, this study raises historical exposure to noise as a previously unrecognised but vitally important consideration for studies of aquatic noise.

The biofiltration capacity of bivalve populations is known to alleviate the effects of coastal eutrophication. However, this important ecosystem service could potentially be impaired by the increasing microplastic abundance in near shore environments. It is known that relatively large microplastics (∼500 μm) impair the filtration capacity of bivalves. However, the effect of smaller microplastics, and specifically microfibers, is not known even though they are more common in many natural systems and similar in size to phytoplankton, the main food source of mussels. Here, we investigated the effects of long-term exposure to microfibers (MFs), which are smaller than 100 μm, on the biofiltration capacity of the blue mussel, Mytilus edulis. Our findings show that long-term exposure (here 39 days) to microfibers significantly reduced (21%) the clearance of phytoplankton (Tetraselmis sp). While previous studies have shown that larger microplastics can decrease the filtration capacity of mussels after short-term exposure, our findings suggest that, for smaller MFs, mussel’s clearance capacity is significantly affected after long-term exposure (39 days in this study). This may be due to the accumulation of MFs in the digestive system. In addition, the most efficient phytoplankton consumers were more susceptible to MF accumulation in the digestive system. This suggests that prolonged exposure to MF of coastal mussels could negatively impact the biofiltration of more potent individuals, thus decreasing the ecosystem service potential of the population as a whole.

Eleven years, January 2008 to June 2019, of hourly nitrogen dioxide (NO₂) levels recorded at El Arenosillo observatory (Southwestern Europe) were analyzed. Annual averages ranged between 4 μg m⁻³ and 6 μg m⁻³ with peaks exceeding 40 μg m⁻³. A slight monthly variation was observed with maximum and minimum values in the cold (∼6 μg m⁻³) and warm (∼4 μg m⁻³) seasons respectively. A diurnal pattern was found with a weak amplitude (∼3 μg m⁻³). The monthly trends were investigated using surface observations and OMI (Ozone Monitoring instrument) satellite measurements. An unexpected upward trend was obtained in the last five years. The periods with elevated NO₂ concentrations in the last years were analyzed, showing an increase in its frequency and concentrations, linked with the upward trend observed. The weather conditions in these NO₂ peaks were studied using local surface meteorology, mean sea level pressure and wind fields from the data reanalysis of ERA5. The transport of NO₂ was explored using TROPOMI (Tropospheric Monitoring Instrument) measurements. The events occurred under conditions governed by high-pressure systems, which induced weak synoptic airflows or the development of mesoscale processes. Four scenarios of NO₂ transport were identified, associated with weak synoptic flows from inland or Southern Portugal and with mesoscale processes. The gulf of Cadiz plays an important role as a reservoir where the NO₂ coming from the south of Portugal, the Western Mediterranean Basin and urban-industrial areas can be accumulated and later transported inland. A strong correlation was found between the increase of NO₂ observed in the last years and positive anomalies of the temperature and geopotential height at 850 and 500 hPa levels. These findings could indicate that the causes of the changes in the NO₂ would be attributed to alterations in the weather patterns associated with a warmer climate.

Perfluorooctanoic acid (PFOA) is an emerging persistent organic pollutant which has been identified at significant levels in soils. Existed ecotoxicological studies have mainly employed earthworms to evaluate the toxicity of PFOA. However, little information do we know about the toxicity of PFOA regarding soil microorganisms. Accordingly, the adverse effects of PFOA on microbial activity in a wheat soil under four fertilization treatments were investigated in this study. The microcalorimetric results revealed that the toxicity of PFOA on soil microbial activity in four treatments followed a descending sequence: Control (no fertilization), NK (no P fertilizer, but N and K fertilizers were used), PK (no N fertilizer, but P and K fertilizers were used), and NPK (N, P and K fertilizers were used). The soil sample with higher available P content had higher resistant to PFOA. There were significant differences in urease activity and alkaline phosphatase activity among the four fertilization treated soils. Molecular modeling studies clearly demonstrated that the binding of PFOA with alkaline phosphatase was more stable than with urease through electrostatic interaction, van der Waals force, and hydrogen bonds. These results are expected to provide more comprehensive information in toxicity of PFOA in soil environment.

Properly increasing mobility of heavy metals could promote phytoremediation of contaminated soil. Fe₁₋ₓS/biochar was successfully prepared from sawdust with loading pyrrhotite (Fe₁₋ₓS) at a pyrolysis temperature of 550 °C. Thiobacillus were successfully adsorbed and enriched on the surface of Fe₁₋ₓS/biochar. Microbial growth for 36 d supported by bio-oxidization of Fe₁₋ₓS decreased the system pH from 4.32 to 3.50, increased the ORP from 298 to 487 mV, and the Fe³⁺ release reached 25.48 mg/g, enhancing the oxidation and leaching of soil Pb. Finally, Fe₁₋ₓS/biochar and Thiobacillus were simultaneously applied into Pb-contaminated soil for 60 d, the soil pH decreased from 7.83 to 6.72, and the exchangeable fraction of soil Pb increased from 22.86% to 37.19%. Ryegrass planting for 60 d in Pb-contaminated soil with Fe₁₋ₓS/biochar and Thiobacillus showed that the Pb content in shoot and root of ryegrass increased by 55.65% and 73.43%, respectively, confirming an obvious increase of phytoavailability of soil Pb. The relative abundance of Thiobacillus in remediated soil significantly increased from 0.06% to 34.55% due to the addition of Fe₁₋ₓS/biochar and Thiobacillus. This study provides a novel approach for regulating the Pb phytoavailability for phytoremediation of Pb-contaminated soil.

Advanced oxidation processes based on carbon catalysis is a promising strategy possessing great potential for environmental pollution degradation. Herein, nitrogen-doped biochar nanosheets (NCS-x) were synthesized using a nitrogen-rich biomass (Candida utilis) as sole precursor. The involvement of environmental-friendly molten salt (NaCl and KCl) in pyrolysis process not only facilitated the exfoliation of biochar, but also favored the retention of N element in biochar. When applying as catalyst for peroxymonosulfate activation, the as-obtained NCS-6 exhibited outstanding performance in catalytic degradation of bisphenol A (BPA). A 100% removal efficiency was observed in 6 min with fast reaction kinetic (k = 1.36 min⁻¹). Based on quenching test and in-situ electron paramagnetic resonance analysis, both radical pathway and non-radical pathway were suggested to be involved in BPA degradation, while singlet oxygen was identified as the dominant reactive oxygen species. Furthermore, the ecotoxicity evaluation using Chlorella vulgaris as ecological indicator indicated that BPA solution after degradation was less toxic than the original solution. It is expected that this green and facile strategy holds great promise for value-added conversion of nitrogen-rich biomass to highly efficient biochar nanosheets for environment remediation.

Kaolinite supported CoFe₂O₄ (KCF) was synthesized and employed to adsorb doxycycline (DOX), an antibiotic and Congo red (CR), a dye from aqueous solution. The prepared KCF nanocomposite was treated in a muffle furnace at 300, 500 and 700 °C, and thereafter characterized. X-ray diffractogram revealed structural damage of kaolinite and appearance of distinct peaks of CoFe₂O₄ with an increase in calcination temperature, while transmission electron microscopy (TEM) images showed that CoFe₂O₄ nanoparticles were supported on the lamellar surface of kaolinites. Comparative adsorption mechanism of the two targeted contaminants showed that adsorption of DOX was influenced by hydrogen bond and n-π interaction, while that of CR was due to hydrophobic interaction and hydrogen bond. However, the adsorption of the two contaminants was best fitted to the isotherm that was proposed by Langmuir, with a monolayer maximum adsorption capacity of 400 mg g⁻¹ at 333 K for DOX, and 547 mg g⁻¹ at 298 K for CR. The removal of DOX from aqueous solution was favored by an increase in temperature (endothermic), while that of CR was exothermic. Thermodynamics studies confirmed that the adsorption of the two contaminants is feasible and spontaneous. The presence of natural organic matter (NOM) did not affect the removal of the two contaminants. Regeneration and reusability study showed that KCF is economically viable. Therefore, introducing inorganic particles like cobalt ferrite into the matrix of kaolinites provides a composite with promising adsorption capacity.

Chlorpyrifos is one of the most heavily used pesticides in domestic and agricultural insect prevention globally. Given the potential neurotoxicity of chlorpyrifos and its high detection rates in food and drinking water, health risks attributable to chlorpyrifos residue in Chinese drinking water and food in both China and Denmark were assessed in this study. Mixed left-censored handling models were used to deal with the non-detected values in chlorpyrifos concentrations. Results show that chronic exposure imputed to chlorpyrifos residue is much lower than the reference dose, and will thus not pose appreciable health risk to the consumer. Compared to the total exposure from chlorpyrifos in drinking water and food sources, chronic exposure from drinking water sources in China accounts for 0–4.4%. Health risk owing to chlorpyrifos in food within China is 6-7-fold higher than in Denmark, and this coincides with the fact that all application of chlorpyrifos is banned in Denmark, in contrast to China. However, the Danish consumers are still exposed from imported food items. The main health risk contributors in China are the food groups of Grains and grain-based products and Vegetable and vegetable products, while the main chronic health risk contributor in Denmark is the food group of imported fruit and fruit products.