The development of saline-alkali lands has contributed to the increasing discharge of alkaline salt-laden wastewater, which poses a threat to aquatic organisms. However, the comprehensive effect of alkaline salt on Microcystis aeruginosa, a harmful cyanobacterium, remains unclear. In this study, the growth, physiology, cell ultrastructure and production of microcystin-LR (MC-LR) in Microcystis aeruginosa exposed to four levels of alkaline salt stress were evaluated. The growth of Microcystis aeruginosa was stimulated at an electrical conductivity (EC) of 2.5 mS/cm compared to the control, as supported by the increased cell density, photosynthetic pigment and protein contents. Microcystis aeruginosa could tolerate a certain level of alkaline salt (i.e., EC of 5 mS/cm) via increasing photosynthetic pigment contents to protect cells from alkaline salt stress, but the antioxidant defence system and cell ultrastructure were not affected. When EC increased to 7.5 mS/cm, alkaline salt caused oxidative stress and toxicity in Microcystis aeruginosa, as evidenced by analysis of the integrated biomarker response (IBR). Furthermore, the photosynthetic pigment and protein contents decreased, and cell apoptosis associated with ultrastructural changes was observed. Therefore, we propose that EC of 7.5 mS/cm is a threshold for growth of Microcystis aeruginosa. Additionally, the intracellular MC-LR content was stimulated by alkaline salt, and the highest value was observed at EC of 2.5 mS/cm. The extracellular MC-LR content increased with the increasing alkaline salt concentration. When EC was 7.5 mS/cm, the extracellular MC-LR content was significantly higher than in the control and was associated with the upregulated mcyH gene. This study recommends that more attention should be paid to the risk of Microcystis aeruginosa bloom and microcystin-LR pollution in lakes located in salinization regions.

Estuaries are one of the most valuable biomes on earth. Although humans are highly dependent on these ecosystems, anthropogenic activities have impacted estuaries worldwide, altering their ecological functions and ability to provide a variety of important ecosystem services. Many anthropogenic stressors combine to affect the soft sedimentary habitats that dominate estuarine ecosystems. Now, due to climate change, estuaries and other marine areas might be increasingly exposed to the emerging threat of megafires. Here, by sampling estuaries before and after a megafire, we describe impacts of wildfires on estuarine benthic habitats and justify why megafires are a new and concerning threat to coastal ecosystems. We (1) show that wildfires change the fundamental characteristics of estuarine benthic habitat, (2) identify the factors (burnt intensity and proximity to water's edge) that influence the consequences of fires on estuaries, and (3) identify relevant indicators of wildfire impact: metals, nutrients, and pyrogenic carbon. We then discuss how fires can impact estuaries globally, regardless of local variability and differences in catchment. In the first empirical assessment of the impact of wildfires on estuarine condition, our results highlight indicators that may assist waterway managers to empirically detect wildfire impacts in estuaries and identify catchment factors that should be included in fire risk assessments for estuaries. Overall, this study highlights the importance of considering fire threats in current and future estuarine and coastal management.

Sixteen paired surface sediment samples (0–5 cm, n = 32) covering upstream to downstream of water-level-fluctuation zone of Three Gorges Reservoir, China were collected in March 2018 (following six months of submergence) and September 2018 (after six months of exposure). Seventeen per- and poly-fluoroalkyl substances (PFASs) were quantified to evaluate contamination characteristics, apportion source categories and estimate mass inventory and loadings. The concentration of ΣPFASs ranged from 0.26 to 0.82 ng·g⁻¹ at high water-level (HWL) and 0.46–1.53 ng·g⁻¹ at low water-level (LWL). Perfluorooctanoic acid (PFOA, mean: 0.32 ng·g⁻¹) and perfluorooctane sulfonate (PFOS, mean: 0.12 ng·g⁻¹) dominated, accounting 44.9% and 16.3% of the total PFASs, respectively. The distribution of PFASs was more influenced by anthropogenic activities than physicochemical parameters of the sediments. Positive matrix factorization (PMF) identified PFOA-based products was the major sources (40.1% and 38.6%, respectively). Besides, the direct sources of PFOA-, PFOS-, PFNA-and PFBA-based products played the predominant role, while the indirect degradation of precursors contributed relatively little. The sediment (0–5 cm) mass inventory of PFASs at LWL (57.5 kg) was higher than HWL (39.3 kg). The annual mass loadings of the total PFASs, PFOA, PFOS, perfluoroundecanoic acid (PFUdA) and perfluorononanoic acid (PFNA) from the upstream to the middle-lower reaches of Yangtze River were 27.4 kg, 11.1 kg, 4.63 kg, 2.89 kg and 2.57 kg, respectively. This study could provide the basic datasets of PFASs in surface sediments of the TGR, and also indicate an important transport of PFASs from upstream to the lower reaches, which should be further studied as well.

The willingness of migrating due to air pollution is widespread in China. However, there is a lack of direct evidence and discussion regarding whether this willingness has been translated into action. In this study, PM2.5 concentrations were used to represent air pollution in each city and were compared with individual migration data from the China Labor-force Dynamics Survey (CLDS) to examine population migration effects caused by air pollution. This study showed that (1) Population migration between Chinese cities shows sensitivity to air pollution, and air pollution increases the probability of moving away for local population. This finding is held under multiple robustness and endogeneity tests. (2) Population migration effects caused by air pollution were more pronounced among women, middle-aged people, those with lower educational levels, from agricultural households, Han Chinese groups, and populations in southern cities. (3) The use of individual self-rated health data verified that physical health is an important channel through which individual migration decisions are influenced by air pollution, the older an individual, the more his or her health was affected. In light of these findings, this study led to conclusions regarding targeted policy recommendations in terms of talent clustering, social equity, and demographic balance.

Many communities around the country are undergoing contentious battles over the installation of artificial turf. Opponents are concerned about exposure to hazardous chemicals leaching from the crumb rubber cushioning fill made of recycled tires, the plastic carpet, and other synthetic components. Numerous studies have shown that chemicals identified in artificial turf, including polycyclic aromatic hydrocarbons (PAHs), phthalates, and per- and polyfluoroalkyl substances (PFAS), are known carcinogens, neurotoxicants, mutagens, and endocrine disruptors. However, few studies have looked directly at health outcomes of exposure to these chemicals in the context of artificial turf. Ecotoxicology studies in invertebrates exposed to crumb rubber have identified risks to organisms whose habitats have been contaminated by artificial turf. Chicken eggs injected with crumb rubber leachate also showed impaired development and endocrine disruption. The only human epidemiology studies conducted related to artificial turf have been highly limited in design, focusing on cancer incidence. In addition, government agencies have begun their own risk assessment studies to aid community decisions. Additional studies in in vitro and in vivo translational models, ecotoxicological systems, and human epidemiology are strongly needed to consider exposure from both field use and runoff, components other than crumb rubber, sensitive windows of development, and additional physiological endpoints. Identification of potential health effects from exposures due to spending time at artificial turf fields and adjacent environments that may be contaminated by runoff will aid in risk assessment and community decision making on the use of artificial turf.

Understanding the spatial patterns of atmospheric pollutants in urban and suburban areas is important for evaluating their effects on regional air quality, climate, and human health. The analyses of pollutant monitoring data of the China National Environmental Monitoring Center revealed that the differences in the concentrations of ambient O₃, PM₂.₅, NO₂, SO₂, and CO between urban and suburban areas rapidly decreased from 2014 to 2019 in Beijing. Considering the negligible urbanization and interannual meteorological changes during the study period, the results reveal a quick response of the urban-to-suburban difference (ΔUᵣbₐₙ₋Sᵤbᵤᵣbₐₙ) in the ambient pollutants concentrations to emission reduction measures implemented in China in 2013. However, owing to the efficient O₃ formation in summer in urban areas in recent years, we observed a more rapid decrease in the ΔUᵣbₐₙ₋Sᵤbᵤᵣbₐₙ in O₃ concentration in summer (64.8%) than in winter (16.1%). In addition, the ΔUᵣbₐₙ₋Sᵤbᵤᵣbₐₙ in daytime summer O₃ changed from negative in 2014–2018 to positive in 2019, indicating that the daytime O₃ concentration in urban areas exceeded that in suburban areas. Furthermore, instantaneous changes in ΔUᵣbₐₙ₋Sᵤbᵤᵣbₐₙ in air pollutants were more sensitive to meteorological variations in 2014 than in 2019. The results indicate a less significant role of regional air mass transport in the spatial variability of pollutants under a future scenario of strong emission reduction in China.

In this study, we assessed the impact of zinc oxide (ZnO) and iron oxide (FeO) (<36 nm) nanoparticles (NPs) as well as their sulphate salt (bulk) counterpart (0, 25, 100 mg/kg) on rice growth and seed quality as well as the microbial community in the rhizosphere environment of rice. During the rice growing season 2021–22, all experiments were conducted in a greenhouse (temperature: day 30 °C; night 20 °C; relative humidity: 70%; light period: 16 h/8 h, day/night) in rice field soil. Results showed that low concentrations of FeO and ZnO NPs (25 mg/kg) promoted rice growth (height (29%, 16%), pigment content (2%, 3%)) and grain quality parameters such as grains per spike (8%, 9%), dry weight of grains (12%, 14%) respectively. As compared to the control group, the Zn (2%) and Fe (5%) accumulations at their respective low concentrations of NP treatments showed stimulation. Interestingly, our results showed that at low concentration of both the NPs the soil microbes had more diversity and richness than those in the bulk treated and control soil group. Although a number of phyla were affected by the presence of NPs, the strongest effects were observed for change in the abundance of the three phyla for Proteobacteria, Actinobacteria, and Planctomycetes. The rhizosphere environment was notably enriched with potential streptomycin producers, carbon and nitrogen fixers, and lignin degraders with regard to functional groups of microorganisms. However, microbial communities mainly responsible for chitin degradation, ammonia oxidation, and nitrite reduction were found to be decreased. The results from this study highlight significant changes in several plant-based endpoints, as well as the rhizosphere soil microorganisms. It further adds information to our understanding of the nanoscale-specific impacts of important micronutrient oxides on both rice and its associated soil microbiome.

The purpose of this study was to investigate antibiotic resistant fungal (ARF) communities in pig manure (PM) composting employing two different biochar (coconut shell-CSB and bamboo biochar-BB) as amendment. Three treatments (Control, 10% CSB and 10% BB) were designed and indicated with T1 to T3. Experimental results declared that the fungal abundance significantly reduced among the both biochar applied treatments but three dominant phyla Ascomycota, Basidiomycota and Mucoromycota were still relatively greater abundance present. There were significant differences (p < 0.05) in the relative abundance and diversity of fungi among all three treatments. Interestingly, biochar addition regulated the overall fungal community in final compost. Compared with the control group, the abundance of fungi was positively mobilized, and especially CSB showed a better effect. Conclusively, biochar has potential to inhibit and reduce the ARGs population and mobility in compost. Thus, these findings offer new insight to understand the succession of ARFs during PM composting.

With increased forest fires due to climate change, PM₂.₅ emissions also intensified. Record PM₂.₅ emissions according to Copernicus Atmosphere Monitoring Service in Russia amounted to 8 megatons (Mt) in 2021, which is 78% higher than the average level of 2004–2021 (4.5 Mt). Seven federal subjects (the constituent entities) with vast forest areas without fire protection produced 86% of emissions (6.8 Mt) in 2021, the major losses (6.1 Mt) in Yakutia (Sakha Republic). The ambient temperature in Eastern Siberia is increasing, especially in months of winter and spring seasons (up to +3.6 °C) in 1990–2020 compared to 1901–2020 (CEDA Archive); climate change has affected meteorological conditions leading to increased forest fires. The results of the SARIMAX model study for PM₂.₅ emissions considering meteorological factors using ERA5 and burnt forest area using MODIS (MCD64A1), establishing a significant dependence of PM₂.₅ emissions on the lack of precipitation and the associated parameters of complete and potential evaporation. This influence long before the fire season (up to 9 months), as it affects the snow cover and the dryness of the fuel by the beginning of forest fires. In turn, high PM₂.₅ emission values are accompanied by a drop in 2 m air temperature and surface solar radiation downwards due to the aerosol saturation with suspended particles. The average COR for seven federal subjects was 0.79, with the highest forecast result in Yakutia (0.95), indicating the maximum propensity for record emissions due to weather conditions. In combination with forest management without fire protection, meteorological parameters have caused an increase in PM₂.₅ emissions in recent years in Siberia. The forest needs other ways to manage under the pressures of climate change to reduce environmental pollution associated with PM₂.₅ emissions from vast Siberian fires.

Various precursor emissions and chemical mechanisms for secondary organic aerosol (SOA) formation were incorporated into a regional air quality model system (RAQMS) and applied to investigate the distribution, composition, and source contribution of SOA over east China in summer 2018. Model comparison against a variety of observations at a national scale demonstrated that the model was able to reasonably reproduce meteorological variables, O₃ and PM₂.₅ concentrations, and the model simulated SOA concentration generally agreed with observations, with the overall NMB of 7.0% and R of 0.4 in 10 cities over east China. The simulated period-mean SOA concentrations of 4–15 μg m⁻³ were mainly distributed over the North China Plain (NCP), the middle and lower reaches of the Yangtze River and Chongqing district. SOA dominated organic aerosol (OA) over China in summertime (90%). The percentage contributions to SOA from ASOA (SOA produced from anthropogenic volatile organic compounds (AVOC)), BSOA (SOA produced from biogenic volatile organic compounds (BVOC)), DSOA (SOA produced from aqueous uptake of glyoxal and methylglyoxal) and S/I-SOA (SOA produced from semi-volatile and intermediate volatile organic compounds) were estimated to be 48.3%, 28.6%, 14.3%, and 8.8% respectively, over east China in summertime. In terms of domain and period average, ASOA contributed most to SOA (59%) in north China, while BSOA contributed most to SOA (37.3%) in northeast China. The percentage contribution of DSOA to SOA reached 21.5% in southwest China. S/I-SOA accounted for approximately 10% of SOA in most areas of east China. This study reveals that while AVOC dominates SOA formation on average over east China, the SOA source contributions differ considerably in different regions of China. BVOC makes the same contribution to SOA formation as AVOC in northeast China and southwest China, where forest coverage and BVOC emission are higher and anthropogenic emissions are relatively low, highlighting the significant role of BVOC in summer SOA formation in China.