East-central China Research Articles

The altered drivers of evapotranspiration trends around the recent warming hiatus in China

AbstractThis study focuses on the trends and the causes of variation in actual evapotranspiration (AET) around the warming hiatus over China by a comprehensive analysis applying various temporal–spatial methods. It is observed that the annual AET showed a different trend around 2000 for China as a whole. By employing segmented regression analysis for detecting warming hiatus points, high temporal inconsistency can be found in eight climatic regions of China. The impacts of meteorological variables on AET were further identified by affecting the intensity and relative change of meteorological factors. AET was highly correlated (p < .01) with solar radiation in the southeast (R = 0.80) and air specific humidity in the northwest areas (R = 0.83). AET changes presented the highest sensitivity to specific humidity in Northwest before 2006 and in north central China after 2003, with sensitivity coefficients of 1.48 and 1.74, respectively. Three variables, including air specific humidity (with an average contribution rate of ~17% in the northwest), short‐wave radiation and air temperature, can be the main factors that lead to the changes in AET. The specific meteorological factors varied from region to region: the changes in AET can be ascribed to the increased wind and short‐wave radiation in north central China and east China, the decreased air temperature in Tibetan Plateau, the increased specific humidity in southeast China during warming hiatus, and so on. After the warming hiatus occurred, the dominant factor of AET trends changed from air specific humidity to short‐wave radiation and other factors. Generally, air specific humidity and air temperature have played leading roles in AET trends during the past 30 years.

Lithospheric Structure in Central-East China from Joint Inversion of Surface-Wave Dispersion and CCP-Derived Receiver Function: Implications for Regional Tectonics

Abstract To investigate the lithospheric deformation beneath central-east China, we constructed a 3D crustal and uppermost-mantle velocity model of this region by joint inversion of Rayleigh-wave phase velocities and common conversion point-derived receiver functions. The velocity images at the east and west sides of Xuefeng Mountain presented quite different features and a sharp change in lithospheric thickness beneath this mountain, suggesting that this mountain may be the southwestern segment of the boundary between the Yangtze craton (YZC) and the Cathaysia block (CAB). We observed extensive lithospheric thinning in the eastern South China block (SCB), including the CAB and lower YZC. Considering that the eastern SCB is within the influence of the circum-Pacific system and features intensive Mesozoic magmatic activity, we deduced that subduction of the Pacific plate was the main controlling factor of lithospheric thinning. The westward extension of lithospheric thinning in the SCB terminates in the area east of the north–south gravity lineament. We observed a large-scale, low-velocity zone in the uppermost mantle of the southern Trans-North China orogen that penetrates northwestward into the southeastern corner of the Ordos block. The low-velocity zone intrudes into the bottom of the crust and results in crustal thinning in the region. We proposed that both the southern Trans-North China craton and the southeastern Ordos block are suffering ongoing lithospheric mantle modification.

Prevalence of allergic rhinitis in Chinese children from 2001 to 2021: Meta analysis

Objective: To analyze the prevalence of allergic rhinitis in Chinese children from 2001 to 2021, in order to provide data support for the prevention and treatment of allergic rhinitis in children. Methods: "Allergic rhinitis" "children" "adolescent" "infant" "prevalence" "epidemiology" were used in the main search terms. The combination of Mesh words and free words was adopted. CNKI, CBM, VIP, WanFang Data, PubMed, Web of Science, Embase and The Cochrane Library for publications between January 1, 2001 and December 31, 2021 were searched systemically and data were extracted from eligible studies by two independent reviewers. Supplementary collection was made by identifying retrospective references from the included literature. After study quality assessment, Meta analysis was completed using Stata 16.0 software. Results: A total of 20 cross-sectional studies were included, involving 54 886 cases. Meta analysis results showed that the overall prevalence of allergic rhinitis among the participants was 18.46% (95%CI:14.34%-22.59%). Subgroup analysis showed that the prevalence of allergic rhinitis from 2012 to 2021 (19.75%) was higher than that from 2001 to 2011 (14.81%), and the difference was statistically significant (P<0.001). The prevalence of different regions from high to low was East China (22.77%), North China (20.82%), Northwest China (17.77%), Central China (16.62%), Southwest China (16.33%), Northeast China (16.16%) and South China (7.29%) respectively, the difference was statistically significant (P<0.001). The prevalence of male (20.73%) was higher than that of female (16.34%), and the difference was statistically significant (P<0.001). The prevalence of Han nationality(17.31%) was higher than that of ethnic minorities (15.93%), and the difference was statistically significant (P<0.001). Conclusion: The prevalence of allergic rhinitis in Chinese children is high and the prevalence in children varies by publication year, region, sex and nationality.

Ozone Pollution in Chinese Cities: Spatiotemporal Variations and Their Relationships with Meteorological and Other Pollution Factors (2016–2020)

With the acceleration of urbanization, ozone (O3) pollution has become increasingly serious in many Chinese cities. This study analyzes the temporal and spatial characteristics of O3 based on monitoring and meteorological data for 366 cities and national weather stations throughout China from 2016 to 2020. Least squares linear regression and Spearman’s correlation coefficient were computed to investigate the relationships of O3 with various pollution factors and meteorological conditions. Global Moran’s I and the Getis–Ord index Gi* were adopted to reveal the spatial agglomeration of O3 pollution in Chinese cities and characterize the temporal and spatial characteristics of hot and cold spots. The results show that the national proportion of cities with an annual concentration exceeding 160 μg·m−3 increased from 21.6% in 2016 to 50.9% in 2018 but dropped to 21.5% in 2020; these cities are concentrated mainly in Central China (CC) and East China (EC). Throughout most of China, the highest seasonal O3 concentrations occur in summer, while the highest values in South China (SC) and Southwest China (SWC) occur in autumn and spring, respectively. The highest monthly O3 concentration reached 200 μg·m−3 in North China (NC) in June, while the lowest value was 60 μg·m−3 in Northeast China (NEC) in December. O3 is positively correlated with the ground surface temperature (GST) and sunshine duration (SSD) and negatively correlated with pressure (PRS) and relative humidity (RHU). Wind speed (WIN) and precipitation (PRE) were positively correlated in all regions except SC. O3 concentrations are significantly differentiated in space: O3 pollution is high in CC and EC and relatively low in the western and northeastern regions. The concentration of O3 exhibits obvious agglomeration characteristics, with hot spots being concentrated mainly in NC, CC and EC.

Contribution to the Knowledge of Trichoptera from Dabie Mountains, East Central China, with Descriptions of Seven New Species

ABSTRACT Seven new species from east-central China are described and illustrated in this article, they are: Philopotamidae: Kisaura segmentalis Qiu sp. nov.; Wormaldia truncata Qiu, sp. nov.; Stenopsychidae: Stenopsyche truncata Qiu, sp. nov.; Molannidae: Molannodes arcuatus Qiu, sp. nov.; Uenoidae: Uenoa megalobata Qiu, sp. nov.; Glossosomatidae: Agapetus elongatus Qiu sp. nov. and Rhyacophilidae: Rhyacophila yingshanensis Qiu sp. nov. In addition, Macrostemum bacham Hoang, Tanida and Bae, 2005, is reported as a new record in China, with re-description referring to variations in this species. Four species, Diplectrona burha; Stactobia leptoclada; Hydroptila giama and Leptocerus cauliculus are also recorded for the first time in Hubei Province.

Analysis of atmospheric ozone in Fenwei Plain based on remote sensing monitoring.

This study uses the daily product data of the concentration of ozone in the atmospheric column (ozone column concentration) collected by the Aura satellite's Ozone Monitoring Instrument (OMI), to evaluate the ozone pollution status of the Fenwei Plain in east-central China, by employing pixel-based spatial analysis, an θslope trend index, a Hurst index, and grey correlation. The following results were found. (1) The spatial distribution of ozone in the atmosphere of the Fenwei Plain was higher in the north and lower in the south, with high values appearing in Jinzhong, Lvliang, and other cities. (2) The changes in ozone column concentration periodically and seasonally in the Fenwei Plain. Seasonally, the ozone column concentration was highest in spring, followed by summer, winter, and autumn. (3) The pixel-based trend change of the ozone slope (θslope) indicated that the ozone concentration in the region was in a downward trend, while the long-term correlation of the time series trend Hurst index found that the region should expect to see a weak rebound in the ozone column concentration in the future, so that routine monitoring should be strengthened. (4) The present study on the factors influencing the ozone concentration found that the concentration is relatively closely related to temperature, air pressure, humidity, grain sowing area, highway mileage, and secondary industry.

Characteristics of human oral microbiome and its non-invasive diagnostic value in chronic kidney disease.

Background: Morbidity of chronic kidney disease (CKD) is increased, with many complications and high mortality rates. The characteristics of oral microbiome in CKD patients have not been reported. This study aims to analyze the oral microbiome, and to demonstrate the potential of microbiome as noninvasive biomarkers for CKD patients.Methods: The study collected 253 oral samples from different regions of China (Central China and East China) prospectively and finally 235 samples completed Miseq sequencing, including 103 samples from CKD patients and 132 healthy controls (HCs).Results: Compared with HCs (n=88), the oral microbial diversity in CKD patients (n=44) was increased. Fourteen genera including Streptococcus, Actinomyces and Leptotrichia were enriched, while six genera including Prevotella and Haemophilus were decreased in CKD patients. Moreover, 49 predicted microbial gene functions including arginine metabolism and tryptophan metabolism increased, while 55 functions including Ribosome and DNA repair recombination proteins decreased. Furthermore, correlation analysis demonstrated that 38 operational taxonomic units (OTUs) were closely related to 5 clinical indicators of CKD. Notably, 7 optimal biomarkers were identified using random forest model, and the classifier model respectively reached an area under the curve (AUC) of 0.9917 and 0.8026 in the discovery and validation phase, achieving a cross-region validation.Conclusions: We first illustrated the characteristics of the oral microbiome of patients with CKD, identified the potential of oral microbial makers as noninvasive tools for the diagnosis of CKD and achieved cross-region validation.

An overlooked dispersal route of Cardueae (Asteraceae) from the Mediterranean to East Asia revealed by phylogenomic and biogeographical analyses of Atractylodes.

The East Asian-Tethyan disjunction pattern and its mechanisms of formation have long been of interest to researchers. Here, we studied the biogeographical history of Asteraceae tribe Cardueae, with a particular focus on the temperate East Asian genus Atractylodes DC., to understand the role of tectonic and climatic events in driving the diversification and disjunctions of the genus. A total of 76 samples of Atractylodes from 36 locations were collected for RAD-sequencing. Three single nucleotide polymorphism (SNP) datasets based on different filtering strategies were used for phylogenetic analyses. Molecular dating and ancestral distribution reconstruction were performed using both chloroplast DNA sequences (127 Cardueae samples) and SNP (36 Atractylodes samples) datasets. Six species of Atractylodes were well resolved as individually monophyletic, although some introgression was identified among accessions of A. chinensis, A. lancea and A. koreana. Dispersal of the subtribe Carlininae from the Mediterranean to East Asia occurred after divergence between Atractylodes and Carlina L. + Atractylis L. + Thevenotia DC. at ~31.57 Ma, resulting in an East Asian-Tethyan disjunction. Diversification of Atractylodes in East Asia mainly occurred from the Late Miocene to the Early Pleistocene. Aridification of Asia and the closure of the Turgai Strait in the Late Oligocene promoted the dispersal of Cardueae from the Mediterranean to East China. Subsequent uplift of the Qinghai-Tibet Plateau as well as changes in Asian monsoon systems resulted in an East Asian-Tethyan disjunction between Atractylodes and Carlina + Atractylis + Thevenotia. In addition, Late Miocene to Quaternary climates and sea level fluctuations played major roles in the diversification of Atractylodes. Through this study of different taxonomic levels using genomic data, we have revealed an overlooked dispersal route between the Mediterranean and far East Asia (Japan/Korea) via Central Asia and East China.

Global Supply Chain Drivers of Agricultural Antibiotic Emissions in China.

Antibiotic pollution causes serious environmental and social issues. China is the largest antibiotic producer and user in the world, with a large share of antibiotics used in agriculture. This study quantified agricultural antibiotic emissions of mainland China in 2014 as well as critical drivers in global supply chains. Results show that China's agriculture discharged 4131 tons of antibiotics. Critical domestic supply chain drivers are mainly located in Central China, North China, and East China. Foreign final demand contributes 9% of agricultural antibiotic emissions in mainland China and leads to 5-40% of emissions in each province. Foreign primary inputs (e.g., labor and capital) contribute 5% of agricultural antibiotic emissions in mainland China and lead to 2-63% of emissions in each province. Critical international drivers include the final demand of the United States and Japan for foods and textile products, as well as the primary inputs of the oil seeds sector in Brazil. The results indicate the uniqueness of supply chain drivers for antibiotic emissions compared with other emissions. Our findings reveal supply chain hotspots for multiple-perspective policy decisions to control China's agricultural antibiotic emissions as well as for international cooperation.

Prediction of range expansion and estimation of dispersal routes of water deer (Hydropotes inermis) in the transboundary region between China, the Russian Far East and the Korean Peninsula.

Global changes may direct species expansion away from their current range. When such an expansion occurs, and the species colonizes a new region, it is important to monitor the habitat used by the species and utilize the information to updated management strategies. Water deer (Hydropotes inermis) is listed as Vulnerable species in IUCN Red List and is restricted to east central China and the Korean Peninsula. Since 2017, water deer has expanded its range towards northeast China and the Russian Far East. The objective of our study is to provide support for a better understanding of habitat use and provide suggestions for developing conservation strategy. We collected occurrence data in northeast China and the Russian Far East during 2017–2021. We used MaxEnt to predict habitat suitability for water deer and applied Circuitscape to determine possible dispersal routes for the species. We used seven environmental variables, viz., altitude, slope, aspect, distance to built-up area, distance to water source, distance to cropland and distance to roads for habitat suitability prediction. We chose the MaxEnt model (AICc = 2572.86) suitable for our data with the AUC value result of 0.935±0.014. There is good quality habitat for water deer in the boundary area of the Yalu and Tumen River estuaries between China, North Korea, and the Russian Far East, as well as the east and west regions of the Korean Peninsula. We identified three main suitable habitat patches, two of them located in east (NK2) and west (NK3) North Korea, and one in the newly colonized area downstream of the Tumen River along the border of China, Russia, and North Korea (TM1). Elevation, distance to cropland and water sources, and presence of wetlands were the variables that positively contributed to modelling the suitable habitats. Two possible dispersal routes were determined using the circuit theory, one was across the area from North Korea to the downstream Tumen transboundary region (Route B), and the other was across North Korea to the boundary region in China and along the tiger national park in northern China (Route A). A series of protected areas in North Korea, China, and Russia may support the dispersal of water deer. From the study on water deer dispersal, we can understand the existing ecological network in northeast Asia, which will benefit the whole landscape and biodiversity conservation. However, there are many threats present, and there is need for continued monitoring inside and outside the protected areas. Information sharing with stakeholders and carrying out local communities awareness activities are important. The establishment of a Northeast Asia landscape conservation network would help establish monitoring and conservation planning at a broad scale, and this study provides an example of the need for such a network.

Enhancing China's ecological sustainability through more optimized investment

China has tremendously invested in a set of ecological sustainability programs since the late 1970 s. Although the positive ecological benefits for human well-being have dramatically increased, these large-scale investments are still confronted with some drawbacks and lack a more comprehensive and precise understanding. Here, we quantitatively presented an overall portrait of spatial distribution, temporal trends and inter-annual variations of ecological investments for ten representative programs in the period 1978–2018 from national to provincial levels. Overall, the Chinese government has invested US$197.59 billion (in 2015 US$) for all the programs in total with the top three amounts in Southwest China, North China and Northwest China. We found that the investments for all the programs had gone through a rapid increase since 2000 with a much faster growth rate in Central China and East China. At the national level, the investments of ecological sustainability programs showed good stability and continuity. However, their annual investments varied greatly among different provinces. For instance, the Shelterbelt Development Program in Five Regions including the Middle and Lower Reaches of the Yangtze River coastal areas was interrupted for more than ten years and showed weak stability in some specific provinces. It is suggested that China should adopt more optimized investment strategies in terms of distribution, stability and continuity through augmenting government funds and diversifying financial pathways for the ecological sustainability programs.

Impact of Hydroclimate Change on the Management for the Multipurpose Reservoir: A Case Study in Meishan (China)

China holds the largest amount of reservoirs in the world, while more than 80% of them were constructed 50–70 years ago and are approaching a critical stage of their designed lifetime. Before deciding the future of a reservoir, it is essential to find out whether it could still satisfy its original purpose in the context of hydroclimate change under global warming. Here, we present a case study of the Meishan reservoir in east-central China, which was primarily built for irrigation and flood control in the 1950s. We evaluate the impacts of rainfall change on the hedging and releasing rules over the historical period (1969–2008) by instrumental data and future period (2061–2100) based on simulations in a regional rivalry-mitigated scenario from the Coupled Model Intercomparison Project Phase 6. The main conclusions are as follows: (1) the annual total rainfall has a remarkable increasing trend from 2015 to 2100 and the annual precipitation variability exceeds the envelope range during the past 50-year period. The increased precipitation amount mainly occurs in spring (March to May). (2) The optimal regulation cycle is from September to August and from July to June for both historical and future periods. The limiting level during the nonflooded season is lower than the operating water level for more than five months in the historical period, which limits the ability of reservoir regulation and utilization of water resources. However, the water supply is no longer affected by flood control in 2061–2100 because of the redistribution of annual precipitation. (3) The projected irrigation and residential water demands of the Meishan reservoir are stable; thus, the improvement of the total economic benefit will mainly depend on power generation. This case provides a practical guide for many reservoirs serving water supply for small cities in eastern China, where the size of the population and cultivated land area is stagnant and the climate is getting wetter.

Neo-tributary geopolitics in transnational higher education (TNHE): a regional analysis of Sino-foreign higher education partnerships

ABSTRACT This research explores how geopolitics and ‘Neo-tributary’ relations influence the distribution of TNHE partnerships in China. Specifically, this research situates China’s TNHE cooperation in policy reforms and designs since 2010, and explores how geopolitics influences the regional practice of re-organisation of the joint programmes between 2018 and 2020. The findings show that, on one hand, China’s central government prioritises the TNHE partnerships in China’s local regions: East China, Central China and West China; and on the other hand, alongside the traditional partner countries, such as the UK and the US, the emerging BRI region enjoys more new Sino-foreign HE partnerships than other foreign partners. This research develops the discussion based on the categories of trade and diplomacy linkages; cultural assimilation; and image building (Pan, Su-Yan, and Joe Tin-Yau Lo. 2017. “Re-Conceptualizing China's Rise as a Global Power: A Neo-Tributary Perspective.” The Pacific Review 30 (1): 1–25.), and concludes with some of the implications of these trends on the ‘new’ geopolitics of knowledge in a Neo-tributary system.

Azimuthally Anisotropic Structure in the Crust and Uppermost Mantle in Central East China and Its Significance to Regional Deformation Around the Tan‐Lu Fault Zone

AbstractSeismic anisotropy can be linked to different mechanisms, structures, and sources. We constrained the 3‐D depth‐dependent shear wave speed isotropic and azimuthally anisotropic structures with Rayleigh wave phase velocity from ambient noise in central Eastern China. We compared the results with other models and found that in the upper crust, the maximum horizontal stress direction differs mainly from the anisotropy that coincides with the strikes of major faults and geologic structures. We inferred that the anisotropy within proximity of faults might be related to fault fabrics, including fractures that strike parallel to the fast axes. The Tan‐Lu Fault controls the anisotropy in the crust to the uppermost mantle. The direction of fast axes in the fault zone is NNE‐SSW to N‐S, coinciding with the fault strike and trend that matches the fault shape on the surface. Southeastern North China craton has a weak anisotropy in the crust and uppermost mantle. The sources are possibly connected to the thrusting, tight trending folds, and dipping thrusts observed to be sub‐parallel to the Dabie Orogenic Belt (DOB). We propose that the NNE‐SSW Zhangbaling uplift group comes from the extension and ductile shearing in the Tan‐Lu Fault zone and the dragging of the northeastern South China Craton in the crust and the uppermost mantle. The N‐S polarized fast axes in the lower crust and uppermost mantle across the Sulu orogen and Xuzhou thrust‐and‐fold belt are the products of the resultant effect of subduction and deep Tan‐Lu faulting.

Estimating Peak Shaving Capacity Demand of Gas-Fired Power in China From a Regional Coordination Perspective

To meet the carbon neutralization goal and renewable energy development, it is of great significance to promote the construction of gas-fired power generation for power peak shaving. From the perspective of regional coordination (corresponding to three scenarios), this paper systematically calculates the power peak shaving demand and the demand for gas-fired power generation capacity in regions of China, by using Mathematical Programming and Shapley value. Compared with the existing research, this paper may make theoretical contributions to the following aspects: studying more spatial scopes and time scales of peak shaving, analyzing the complete system of “coal power—renewable energy—gas power”, and applying cooperative game model to peak shaving issue. We find that, firstly, compared with the scenario of independent peak shaving in a single province (Scenario 1), the peak shaving demands of load and renewable energy are greatly reduced in the scenarios of areal coordination (Scenario 2) and national coordination (Scenario 3), especially renewable energy; secondly, abandonment of 110,766 MWh of renewable energy power occurring in Scenario 2 is avoided in Scenario 3. Compared with Scenario 2, the final peak shaving demands of seven areas in China are simultaneously reduced in Scenario 3. The largest reduction rate is 14% from East China. Thirdly, with deep peak shaving restricted by certain constraints, gas power generation for start-stop peak shaving is inevitable. Compared with Scenario 2, national coordination (Scenario 3) can eliminate 120,714 MW of start-stop peak shaving demand (SS-PSD); finally, flexibility retrofit of existing facilities can further significantly curtail SS-PSD. Based on the above research results, some recommendations are put forward, including developing areal coordination and national coordination mechanisms for peak shaving, clarifying allocation plan of SS-PSD based on the fairness principle (i.e., Shapley value) as soon as possible, encouraging East China, Central China, and North China to take the lead in establishing trading markets of SS-PSD, giving priority to meeting the most urgent and economic peak shaving demand, and establishing a coordination mechanism between new and old units for flexibility retrofit.

Spatial-Temporal Evolution of Health Impact and Economic Loss upon Exposure to PM2.5 in China.

Exposure to PM2.5 can seriously endanger public health. Policies for controlling PM2.5 need to consider health hazards under different circumstances. Unlike most studies on the concentration, distribution, and influencing factors of PM2.5, the present study focuses on the impact of PM2.5 on human health. We analysed the spatial-temporal evolution of health impact and economic loss caused by PM2.5 exposure using the log-linear exposure-response function and benefit transfer method. The results indicate that the number of people affected by PM2.5 pollution fluctuated and began to decline after reaching a peak in 2014, benefiting from the Air Pollution Prevention and Control Action Plan. Regarding the total economic loss, the temporal pattern continued to rise until 2014 and then declined, with an annual mean of 86,886.94 million USD, accounting for 1.71% of China’s GDP. For the spatial pattern, the health impact and economic loss show a strong spatial correlation and remarkable polarisation phenomena, with high values in East China, North China, Central China, and South China, but low values in Southwest China, Northwest China, and Northeast China. The spatial-temporal characterisation of PM2.5 health hazards is visualised and analysed accordingly, which can provide a reference for more comprehensive and effective policy decisions.

Evolutionary characteristics and immune mutation of hepatitis C virus genotype 1b among intravenous drug users in mainland, China.

China is one of the countries with the heaviest burden of hepatitis C virus (HCV) worldwide, especially subtype 1b. To better control hepatitis C, insights into the characteristics of dynamic spread and genomic mutations are urgently needed. We retrieved sequences of HCV-1b NS5B among intravenous drug users (IDUs) and general people (Non-IDUs) in China from 2000 to 2011 in NCBI. Bayesian phylogenetic and phylogeographic analyses were used to evaluate the transmission dynamics of HCV-1b. Non-synonymous substitutions were detected to illustrate immune adaptation. Evolutionary history demonstrated that HCV-1b effective population size experienced a sharp increase in 1990. HCV-1b sequences among IDUs had a higher estimated evolutionary rate (5.7185×10-3 substitutions/site/year) than overall (7.7332×10-4 ). 105/136 (77.2%) of HCV-1b sequences clustered into 38 networks. The average non-synonymous HCV-1b immune epitopes among IDUs were 0.211, higher than non-IDUs, especially in the HLA-A*02molecular recognition region. All of these posed significant challenges for the prevention and treatment of HCV. Heterogeneity and genetic linkages of HCV-1b suggest that evolutionary surveillance of HCV in cities in east-central China and among IDUs could not be neglected.

The impact of the aerosol reduction on the worsening ozone pollution over the Beijing-Tianjin-Hebei region via influencing photolysis rates

Due to the implementation of the toughest-ever emission control actions across China from 2013 to present, the aerosols are decreasing annually but ozone is simultaneously increasing, especially over the Beijing-Tianjin-Hebei (BTH) region, where ozone pollution can even spread into winter. Quantifying each impact of aerosols on ozone in all seasons is urgent for the worsening ozone pollution in the improved aerosol air quality. In this study, we focused on the impact of aerosols on ozone via influencing photolysis rates. The air pollutants were simulated over the Central East China (CEC) in 2018 by using the Weather Research and Forecasting with Chemistry (WRF-Chem) model. By implementing emissions with base years of 2014 and 2018, we quantified the increase in ozone (ΔOzone_photolysis) caused by the decreasing aerosol concentrations (ΔPM2.5) by influencing photolysis rates over the BTH region in all seasons. Furthermore, combined with the ozone observations, the contribution of ΔOzone_photolysis to the total changes in ozone (ΔOzone_total) in all seasons was quantitatively discussed. Our results showed that ΔPM2.5 showed obvious seasonal variations, which PM2.5 decreased more significantly in winter and autumn than in spring and summer, although significant reductions in anthropogenic emissions were observed in all seasons. Consistent seasonal variations were also observed in ΔOzone_photolysis, and the mean increases reached 5.5 μg m−3, 2.6 μg m−3, 1.2 μg m−3, and 1.4 μg m−3 in winter, autumn, spring, spring, and summer, respectively. Compared with ΔOzone_total, ΔOzone_photolysis accounted for 36.3%, 17.2%, 3.5% and 10.6% of ΔOzone_total in winter, autumn, spring, and summer, respectively, suggesting that ΔOzone_photolysis was not the primary contributor to the current changes in ozone over the BTH region. However, the 36.3% contribution to ΔOzone_total in winter suggested that ΔOzone_photolysis is still an important contributor and should not be ignored when discussing the formation of high ozone episodes occurring in winter.

Joint Occurrence of Heavy PM2.5 Pollution Episodes and Persistent Foggy Days in Central East China

Although many severe pollution events in Central and East China have been analyzed in recent years, the heavy PM2.5 pollution episode happened on persistent foggy days from January 13 to 18, 2018 was unique, characterized by explosive increase and sharp decrease in PM2.5 (particles with kinetic equivalent diameter less than or equal to 2.5 microns) concentration. Based on hourly data of ground level meteorological parameters, PM2.5 data and CALIPSO-based (the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation) aerosol data, combined with ECMWF (European Centre for Medium-Range Weather Forecasts) reanalysis data and radiosonde temperature profile, a comprehensive analysis was conducted to reveal the meteorological reasons for the evolution of the episode at horizontal and vertical scales. The PM2.5 concentration experienced four stages: a slow-increase phase, rapid-increase phase, rapid-decrease phase, and rebound phase. Results show that because Central and East China (CEC) were located at the back of a high-pressure system, humid southerly winds and near surface inversion (NSI) were responsible for the slow accumulation of pollutants. The rapid-increase phase was attributed to pollution transport at both ground level and in the lower troposphere because of weak cold air invasion. The significant subsidence at 500 hPa and 700 hPa intensified the NSI and led to dense fog. In that case, corresponding to the supersaturated atmosphere, the particles entered the fog droplets and were scavenged partly by deposition at night and were resuspended on the next day when the atmosphere was unsaturated. Our findings provide convincing evidence that surface PM2.5 rapid-decrease phase and the rebound phase were closely associated with dense fog process.

Above and Below-Ground Biomass and Nutrients Stoichiometry of Tamarix Chinensis Grown Under Salinity Soil in East-Central China

Above and Below-Ground Biomass and Nutrients Stoichiometry of Tamarix Chinensis Grown Under Salinity Soil in East-Central China