Freedmanpetersson6285

Air humidity is a key meteorological factor in regulating visibility changes and haze episodes. Based on multi-year historical data of PM2.5 mass concentration, visibility, relative humidity(RH), and specific humidity(q) during winter in Tianjin, the impact of air humidity on PM2.5 mass concentration and visibility was investigated. Between 2015 and 2020, the PM2.5 mass concentration showed an overall decline of 28.0%. The frequency of visibility above 10 km significantly increased between 2015 and 2018, indicating an improvement in visibility during this period. However, the visibility deteriorated again in the winter of 2019 and 2020, with a decreased frequency of visibility above 10 km. Specifically, the mean RH in January and February in 2020 of Tianjin reached 63% and 67%, respectively, which were higher than the historical 30-year average for the same period. The frequency of extremely low visibility(lower than 2 km) rebounded to a level equivalent to that during the winter of 2016. The enhanced air humater than 3.0 g·kg-1, the frequency of PM2.5 mass concentration greater than 75 μg·m-3 is 78% and 80%, respectively. For the air quality forecast during winter, weather conditions with specific humidity greater than 3.0 g·kg-1 should be carefully monitored.In order to systematically study the transmission characteristics of seasonal and typical pollutants in Shijiazhuang, hourly data of ground-level pollutants(PM2.5, PM10, O3, NO2, SO2, and CO) from 46 state-and provincial-controlled stations, and meteorological(temperature, humidity, and wind speed) data from 17 counties in Shijiazhuang City from December 2018 to November 2019 was analyzed. The interpolation(IDW) and correlation analysis were applied to seasonal and temporal spatial patterns of pollutant concentration. The backward trajectories analysis was performed to explore the seasonal transmission pattern and potential source areas of pollution in Shijiazhuang by combining with the global data assimilation system(GDAS). The results indicate that the different seasons have characteristic pollutants, as followsspring(PM10, 48.91%), summer(O3, 81.97%), autumn(PM10 and PM2.5, 47.54% and 32.79%), and winter(PM2.5, 74.44%), which are related to the variation of meteorological conditions. Furthermore, the PM10(, central and western Shanxi and northern Henan are the concentrated sources of potential pollution(WPCWTij ≥ 180 μg·m-3).In recent years, frequent haze episodes have resulted in the deterioration of air quality of the Fenwei Plain during winter and holidays. Besides coal combustion and industrial emissions, the topography and climate of the Fenwei Plain were also the main causes of the haze. The samples were collected in Linfen of Fenwei Plain during the Spring Festival from February 2 to February 13, 2019. The 13 elements(Li, Be, Ti, Rb, Sc, Y, La, Ce, Zr, V, Tl, U, and Sn) in PM2.5 were determined by inductively coupled plasma mass spectrometry(ICP-MS). Combined with the meteorological data, the spatial and temporal distribution of pollutants and potential source analysis were evaluated by cluster analysis and backward trajectory. The average concentration of SO2 was 58.39 μg·m-3 during the sampling period, which exceeded the 24 h average mass concentration limit(50.00 μg·m-3) of national ambient air quality standard(GB 3095-2012). this website The average concentrations of O3, NO2, and CO was 52.15 μg·m-3, 29.02 μg·m-3, and 2.29 mg·m-3, respectively. The results showed that SO2 was the dominated pollutant. NO2 and CO were mainly affected by diffusion from urban areas. The backward trajectory analysis indicated that the basin topography of the Fenwei Plain may be the main cause of the haze. The analysis of potential source contribution function(PSCF) of soil sources showed that the potential dominated areas included Northern Shaanxi, southern Gansu and Southern Ningxia., which were mainly affected by the monsoon climate.To control the spread of the 2019 novel coronavirus(COVID-19), China imposed rigorous restrictions, which resulted in great reductions in pollutant emissions. However, two heavy haze pollution episodes still occurred in Beijing. In this study, we use the air pollutants, aerosol number concentration, and meteorological elements data in Beijing, combined with the HYSPLIT model, to calculate the potential source contribution factor(PSCF) and concentration weight trajectory(CWT), and analyze the characteristics of evolution and potential source apportionment of atmospheric pollutants during the two episodes. The COVID-19 lockdown restrictions had great impacts on the diurnal variations of PM2.5 and black carbon(BC), while small impacts on the diurnal variations of CO, NO2, SO2, and O3. The primary pollutant was PM2.5 during the two haze pollution episodes, and the haze1 episode was mainly local pollution, while haze 2 was mainly local and external transportation pollution. The spectrum of aerosol number concentra mainly distributed in Beijing and its surrounding areas on clean days(before COVID-19), clean days(COVID-19) and haze 1, with weighted concentrations exceeding 2.4, 0.9 and, 4.5 μg·m-3, respectively. The PSCF high value areas of BC on haze 2 was distributed in the southwest of Beijing, and the weight concentration exceeded 5 μg·m-3.The study researched the relationship between vegetation cover and PM2.5 pollution. The raster NDVI dataset from 1998 to 2016 were reclassified into low, medium, and high vegetation coverage area, and the corresponding PM2.5 concentration in eight economic regions in China were then calculated. On this basis, the temporal and spatial characteristics of PM2.5 pollution were analyzed and Pearson correlation coefficient was used to explore its correlation with NDVI landscape pattern indexes separately from landscape and class level NDVI. The preliminary results showed that①The northern, eastern, southern coastal, middle reaches of the Yangtze River, and the northeast economic zones have relatively low vegetation coverage in areas with relatively serious PM2.5 pollution. However, the middle reaches of the Yellow River, the southwestern and the Northwestern Economic Zones in areas with relatively low vegetation coverage showed lighter PM2.5 pollution. ②PM2.5 increased in most areas between 1998 and 2016. ③A significant correlation between PM2.5 and NDVI landscape pattern indexes was not found for all areas. ④Therefore, the impacts of the landscape shape index(LSI), percent of landscape(PLAND), number of patches(NP), largest patch index(LPI), and aggregation index(AI) on PM2.5 are heterogeneous.Hydrogen sulfide(H2S) is one of the most common gas products from modern industrial processes. It is highly toxic, corrosive, and polluting, and poses harm to both the natural environment and human health if it is not properly removed. Biochar has been widely applied for the treatment of environmental pollution due to its excellent adsorption ability, low cost, and wide choice of source materials. Currently, although studies on hydrogen sulfide adsorption by biochar have attracted increasing attention, the factors involved are complex and varied, leading to a necessity to review and summarize the available knowledge and advances. To bridge the research gap, this paper presents the advances in H2S adsorption by biochar, including properties, influencing factors(i.e., biomass feedstock, pyrolysis temperature, residence time, and particle size), control measures(i.e., humidity, adsorption temperature, operating conditions, and modification of biochar by activation), and adsorption mechanism. The work will provide further reference for the preparation and optimization of biochar adsorption conditions to realize a highly efficient removal of H2S.Ground-level ozone pollution(O3) and climate change have become key global problems threatening the environment and sustainable development of urban forests. At present, various studies have assessed the O3 impacts on trees; however, it is difficult to accurately evaluate the complex ecological effects caused by multiple factors on the natural urban environment. In this paper, the interactions between O3 and carbon dioxide(CO2), drought, nitrogen deposition, and warming, as well as the effects of the physiology, biochemistry, and growth of urban trees in China were reviewed. Elevated CO2 could alleviate the negative effects of elevated O3 on the photosynthetic metabolism, antioxidant system, and growth of trees. There is a complex interaction between O3 and drought, which may synergistically aggravate, alleviate, or have no effect on trees. However, there was no correlation between O3 and N deposition, only a significant interaction between elevated temperatures and O3, which slowed down the adverse effects of O3 on tree growth and photosynthesis. Finally, suggestions are put forward to manage and sustainable develop urban forests in China under future climate change and air pollution.Disinfection by-products(DBPs) are secondary pollutants generated by the reaction of disinfectants with organic or inorganic precursors during drinking water disinfection. DBPs have received considerable global attention due to their carcinogenic, teratogenic, and mutagenic characteristics. Focusing on drinking water, this paper introduces the main classification and research history of DBPs, and then summarizes the concentration levels of common DBPs in drinking water, and DBPs regulatory compliance in global drinking water standards. Further, the control strategies for DBPs in drinking water, including source control, process control, DBPs removal and integrated control are introduced together with the advantages and disadvantages. Finally, a summary and review of the current level and future trends of DBPs research in China are presented with the proposed control strategies. On the one hand, when evaluating the control effect of a process or technology, the DBPs concentration and comprehensive toxicity should be considered; on the other hand, in order to realize the efficient control of DBPs in drinking water, the focus should be on the integrated methods coupling different DBPs control methods.

Peanut allergy (PA), a common food allergy, is increasing in prevalence and is associated with high rates of anaphylaxis. Prevalence of food-related anaphylaxis is higher in children and adolescents than in adults, and the pediatric incidence is increasing. We conducted a systematic literature review and meta-analysis to determine the incidence of peanut-induced anaphylaxis in children and/or adolescents with PA.

Literature searches were conducted using the PubMed database and through supplemental methods. Eligible articles for inclusion were peer-reviewed studies published in English that reported the incidence of anaphylaxis in pediatric PA using the 2006 National Institute of Allergy and Infectious Disease/Food Allergy and Anaphylaxis Network criteria, sample size, and follow-up duration. Incidence rates were calculated as person-years at risk or a crude incidence rate was calculated. Meta-analyses of pooled data were conducted using the I

statistic as the measure of heterogeneity.

A total of 830 citations were screened; 8 met the study inclusion criteria and were selected for review. Pooled meta-analysis estimates of the incidence of (1) anaphylaxis among children/adolescents with food allergies, (2) anaphylaxis among children/adolescents with PA, and (3) accidental exposure to peanuts among children/adolescents with PA were 3.72 cases per 100 person-years (95% confidence interval [CI]=2.35, 5.10), 2.74 cases per 100 person-years (95% CI=1.42, 4.05), and 12.28 cases per 100 person-years (95% CI=11.51, 13.05), respectively.

The risks of anaphylaxis among children with food allergies and those with PA contribute to the serious overall burden of PA and food allergy for children and their families.

The risks of anaphylaxis among children with food allergies and those with PA contribute to the serious overall burden of PA and food allergy for children and their families.