East-central China Research Articles

Multiyear Automated Mapping and Price Analysis of Garlic in Main Planting Areas of China Using Time-Series Remote Sensing Images

As one of the major cash crops in China, the accurate area and distribution prediction of garlic is of great significance for the adjustment of the extent under cultivation. In this study, to map garlic in the main planting areas of China, an innovative phenology-based automated classification method was developed. The obtained garlic maps were subsequently used to analyze the relationship between areas under cultivation and garlic prices. The details are summarized as follows. First, we established the normalized difference vegetation index time-series remote sensing images to extract winter crop masks. Second, an improved green chlorophyll vegetation index was designed to distinguish garlic from winter crops using Landsat 8 and Sentinel-2 time-series images. Specifically, we extract the garlic planting areas from 2014 to 2021 in our study areas, located in the main planting areas of east-central China. The quantitative evaluations showed that the proposed method delivered an average overall accuracy varying from 89.89% to 98.68% across the entire study areas. Additionally, we analyzed the relationship between the areas in cultivation and the prices of garlic in multiple years. These results indicate that the price of garlic is highly correlated to the planting behavior of farmers, and the size of the planting areas is one of the main factors to the prices of garlic. The results can guide farmers to adjust their planting areas so as to optimize the garlic market and ensure the maximum benefit to farmers.

Changes in satellite retrievals of atmospheric composition over eastern China during the 2020 COVID-19 lockdowns

Abstract. We examined daily level-3 satellite retrievals of Atmospheric Infrared Sounder (AIRS) CO, Ozone Monitoring Instrument (OMI) SO2 and NO2, and Moderate Resolution Imaging Spectroradiometer (MODIS) aerosol optical depth (AOD) over eastern China to understand how COVID-19 lockdowns affected atmospheric composition. Changes in 2020 were strongly dependent on the choice of background period since 2005 and whether trends in atmospheric composition were accounted for. Over central east China during the 23 January–8 April lockdown window, CO in 2020 was between 3 % and 12 % lower than average depending on the background period. The 2020 CO was not consistently less than expected from trends beginning between 2005 and 2016 and ending in 2019 but was 3 %–4 % lower than the background mean during the 2017–2019 period when CO changes had flattened. Similarly for AOD, 2020 was between 14 % and 30 % lower than averages beginning in 2005 and 14 %–17 % lower compared to different background means beginning in 2016. NO2 in 2020 was between 30 % and 43 % lower than the mean over different background periods and between 17 % and 33 % lower than what would be expected for trends beginning later than 2011. Relative to the 2016–2019 period when NO2 had flattened, 2020 was 30 %–33 % lower. Over southern China, 2020 NO2 was between 23 % and 27 % lower than different background means beginning in 2013, the beginning of a period of persistently lower NO2. CO over southern China was significantly higher in 2020 than what would be expected, which we suggest was partly because of an active fire season in neighboring countries. Over central east and southern China, 2020 SO2 was higher than expected, but this depended strongly on how daily regional values were calculated from individual retrievals and reflects background values approaching the retrieval detection limit. Future work over China, or other regions, needs to take into account the sensitivity of differences in 2020 to different background periods and trends in order to separate the effects of COVID-19 on air quality from previously occurring changes or from variability in other sources.

Seasonal and diurnal patterns of outdoor formaldehyde and impacts on indoor environments and health

Formaldehyde is concerned as an important indoor carcinogen. While contribution of outdoor formaldehyde to indoor concentration is recognized, long-term measurement about its impact on indoor environments remain missing. We measured both outdoor and indoor formaldehyde concentrations for over one year in Nanjing (east-central China) and calculated the outdoor/indoor (O/I) ratios. 64.8% of the measured outdoor concentration have exceeded the chronic reference exposure criteria of 0.009 mg/m3 set by Office of Environmental Health Hazard Assessment (OEHHA). The outdoor concentration was highest in summer with median value of 0.020 mg/m3 and lowest in spring with median value of 0.009 mg/m3. Diurnally, outdoor formaldehyde concentration was highest at noon with median value of 0.013 mg/m3 and lowest at night with median value of 0.01 mg/m3. Health analysis revealed that cancer risk by exposure to this concentration level is 1.6 × 10−4, higher than threshold limit of 10−6. In addition, the median O/I ratios are 0.18 and 0.27 in two offices, indicating that outdoor formaldehyde contributes to indoor concentrations by about one quarter. The change of O/I ratio also shows a similar seasonal and diurnal trend as outdoor concentrations (highest in the summer in a year and at noon in a day). Outdoor formaldehyde concentration is therefore not negligible as a contributor to indoor concentration, especially as indoor concentration limit gets continuously lowered. This factor should be taken into account in indoor air quality design and maintenance.

Recent ozone trends in the Chinese free troposphere: role of the local emission reductions and meteorology

Abstract. Free tropospheric ozone (O3) trends in the Central East China (CEC) and export regions are investigated for 2008–2017 using the IASI (Infrared Atmospheric Sounding Interferometer) O3 observations and the LMDZ-OR-INCA model simulations, including the most recent Chinese emission inventory. The observed and modelled trends in the CEC region are −0.07 ± 0.02 and −0.08 ± 0.02 DU yr−1, respectively, for the lower free troposphere (3–6 km column) and −0.05 ± 0.02 and −0.06 ± 0.02 DU yr−1, respectively, for the upper free troposphere (6–9 km column). The statistical p value is smaller to 0.01 for all the derived trends. A good agreement between the observations and the model is also observed in the region, including the Korean Peninsula and Japan and corresponding to the region of pollution export from China. Based on sensitivity studies conducted with the model, we evaluate, at 60 % and 52 %, the contribution of the Chinese anthropogenic emissions to the trend in the lower and upper free troposphere, respectively. The second main contribution to the trend is the meteorological variability (34 % and 50 %, respectively). These results suggest that the reduction in NOx anthropogenic emissions that has occurred since 2013 in China led to a decrease in ozone in the Chinese free troposphere, contrary to the increase in ozone at the surface. We designed some tests to compare the trends derived by the IASI observations and the model to independent measurements, such as the In-service Aircraft for a Global Observing System (IAGOS) or other satellite measurements (Ozone Monitoring Instrument (OMI)/Microwave Limb Sounder (MLS)). These comparisons do not confirm the O3 decrease and stress the difficulty in analysing short-term trends using multiple data sets with various sampling and the risk of overinterpreting the results.

Modeling for the source apportionments of PM10 during sand and dust storms over East Asia in 2020

Sand and dust storms occur frequently in East Asia, and the dust particles could be transported to most areas of East Asia. To quantify the dust emissions in 18 dust source regions in China and Mongolia and their contributions to PM10 concentrations over East Asia, 10 sand and dust storms (SDSs) episodes in 2020 were simulated using the Comprehensive Air Quality Model with Extensions (CAMx). A dust emission scheme and a tagged method were incorporated. The model well captured the variations of PM10 concentrations during the SDSs episodes. The Gobi deserts in Mongolia were the most important sources of sand and dust in East Asia, with the highest dust emissions, contributing more than 60% to the PM10 concentrations over East-Central China, Japan, and South Korea. The dust emission from Inner Mongolia was about 1/3 of that in Mongolia, and contributed 20–30% to PM10 concentrations over East-Central China, Japan, and South Korea. However, more than 50% of the PM10 concentrations in Inner Mongolia originated from Mongolia in the SDSs events. Few dust aerosols from Taklimakan and Eastern Xinjiang could be transported to the areas further than its surrounding area. Because of the larger contribution of Mongolia to Northern China, the variation of the dust storm frequency in Northern China correlated well with the surface conditions in Mongolia. Anthropogenic emissions contributed less than 5% to the PM10 concentrations over most part of East Asia during the SDSs events.

Comprehensive comparative analysis of air pollutants exposure in different regions of mainland China: Assessment of health impacts and economic burden

This study attempts to explore and compare the exposure to ambient air pollutants (PM10, PM2.5, NO2, SO2, O3 and CO) in various provinces of mainland China during 2017–2019 and to quantitatively assess the extent of health damage and health economic loss of various air pollutants. Notably, the constructed model employed various methods, i.e., the integrated exposure–response model, the contingent valuation method, the human capital method, and the cost of illness method. The results are described as follows. (1) Mortality and morbidity due to exposure to ambient air pollutants in mainland China are estimated to be 13.1 (95%Cl: 7.5–22.2) million and 56.0 (95%Cl: 39.9–108.8) million, respectively, in 2017–2019. The mortality of respiratory diseases (RD) and cardiovascular diseases (CD) was the highest, and acute bronchitis had the highest morbidity. (2) The total economic losses caused by exposure to air pollutants are approximately 1,4444 billion yuan, and the economic losses caused by mortality and morbidity account for 95.2% and 4.8%, respectively. RD and CD account for the highest proportion of economic losses in mortality and morbidity. (3) Central China, East China, and North China have more serious health and economic damage problems caused by air pollution. (4) PM2.5, PM10 and O3 have a significant impact on health, accounting for 78.3% and 63.1%, for the total health damage and economic loss, respectively. The results of the evaluation can provide guidance for the formulation of detailed environmental interventions and further improvement of the air pollution situation in mainland China.

Vegetation Response to Holocene Climate Change in the Qinling Mountains in the Temperate–Subtropical Transition Zone of Central–East China

Global warming is having a profound influence on vegetation and biodiversity patterns, especially in alpine areas and high latitudes. The Qinling Mountain range is located in the transition zone between the temperate and subtropical ecosystems of central–east China and thus the vegetation of the area is diverse. Understanding the long-term interactions between plant diversity and climate change can potentially provide a reference for future landscape management and biodiversity conservation strategies in the Qinling Mountains region. Here, we use a pollen record from the Holocene sediments of Daye Lake, on Mount Taibai in the Qingling Mountains, to study regional vegetation changes based on biomes reconstruction and diversity analysis. Temperature and precipitation records from sites close to Daye Lake are used to provide environmental background to help determine the vegetation response to climate change. The results indicate that climate change was the main factor influencing vegetation and palynological diversity in the Qinling Mountains during the Holocene. The cold and dry climate at the beginning of the early Holocene (11,700–10,700 cal yr BP) resulted in a low abundance and uneven distribution of regional vegetation types, with the dominance of coniferous forest. During the early Holocene (10,700–7,000 cal yr BP), temperate deciduous broadleaf forest expanded, palynological diversity and evenness increased, indicating that the warm and humid climate promoted vegetation growth. In the middle Holocene (7,000–3,000 cal yr BP), the climate became slightly drier but a relatively warm environment supported the continued increase in palynological diversity. After ∼3,000 cal yr BP, palynological diversity and the evenness index commenced a decreasing trend, in agreement with the decreased temperature and precipitation in the Qinling Mountains. It’s noteworthy that human activity at this time had a potential influence on the vegetation. During the past few centuries, however, palynological diversity has increased along with the global temperature, and therefore it is possible that in the short-term ongoing climatic warming will promote vegetation development and palynological diversity in the area without human interference.

Spatial Variation of Surface Ozone Concentration During the Warm Season and Its Meteorological Driving Factors in China

The concentration of surface ozone (O3) in China increased consistently from 2015 to 2018, and became an important air pollutant, followed by particulate matter. This study uses real-time O3 and meteorological data, obtained in 337 cities in China during the warm seasons (April to September) of 2015 to 2018, to determine the spatial variation of surface O3 and its meteorological driving factors in major cities in China, via trend analysis, spatial autocorrelation, hotspot analysis, and multi-scale geographically weighted regression (MGWR) modeling. The results show that: ① during the warm season, O3 concentrations showed a significant growth trend (P<0.05), with an average growth rate of 0.28 μg·(m3·a)-1, while more than 55% of urban O3 concentrations increased by 0.50 μg·m-3 annually. ② There were significant regional differences in O3 concentration. High values (>60 μg·m-3) were distributed over east China, north China, central China, and northwest China, while low values (<20 μg·m-3) were distributed over south China and southwest China. ③ The spatial agglomeration of O3 concentration has been enhanced year by year, with hotspots mainly distributed over east China and central China. In contrast, there are cold spots in northeast China, southwest China, and southern China. ④Analysis of the MGWR model indicated that temperature, wind speed, cloud coverage, and precipitation all have a significant effect on the distribution of O3, although there are also discrepancies in driving factor priorities between the different regions. Temperature was the main meteorological driving factor of O3 variation during the warm season in China, and its impact on O3 concentration was significantly higher in north China, northwest China, and northeast China than in other regions; overall, there was a significant positive correlation between O3 concentration and temperature, except in Guangxi, Yunnan, and Jiangxi. O3 concentration was negatively correlated with wind speed in most regions of south China, east China, and central China, and positively correlated with wind speed in north China and northeast China. O3 concentration was significantly negatively correlated with cloud cover, except in Liaoning, Shandong, Hebei, Gansu, Guangdong, and some areas in southwest China. O3 concentration was significantly negatively correlated with precipitation, except in the northwest and southwest regions.

A Preliminary Study on the Organizational Modes of Mesoscale Convective Systems Associated With Warm‐Sector Heavy Rainfall in South China

AbstractThis work examines the organizational modes of mesoscale convective systems (MCSs) associated with warm‐sector heavy rainfall events in South China based on composite radar reflectivities during April–June from 2007 to 2020. The results showed that these MCSs can be classified into the nonlinear mode (NL) and eight linear modes: trailing stratiform precipitation (TS), no stratiform precipitation (NS), leading stratiform precipitation (LS), parallel stratiform precipitation (PS), embedded lines (EL), bow echoes (BE), training line/adjoining stratiform (TL/AS), and multiple rain bands (MRB). The NL mode accounts for 40% of the total, while linear modes account for 60%, with the TS mode being the most frequent linear mode. The detailed features of the top three most frequent organizational modes (NL, TS, and NS) were examined in this work. First, the MCSs of the top three organizational modes have different formation modes. Eighty‐four percent of NL systems and 77% of TS systems form via the broken areal mode, while 83% of NS systems form via the broken line mode. Second, relative to TS and NS systems, NL systems develop faster and have shorter lifespans but slower movements with higher 3‐h and 6‐h maximum precipitation values. Third, environmental analysis indicates that the Total Totals index (TTI) is significantly different among all the top three organizational modes, with the highest value in TS mode and the lowest value in NS mode. These features are apparently different from their counterparts in central East China due to different synoptic environments.

New Fagaceous pollen taxa from the Miocene Søby flora of Denmark and their biogeographic implications.

The Fagaceae comprise around 1000 tree species in the Northern Hemisphere. Despite an extensive fossil pollen record, reconstructing biogeographic patterns is hampered because it is difficult to achieve good taxonomic resolution with light microscopy alone. We investigate dispersed pollen of Fagaceae from the Miocene Søby flora, Denmark. We explore the latitudinal gradient in Fagaceae distribution during the Miocene Climatic Optimum (MCO) in Europe and the Northern Hemisphere to compare it with the Eocene Warmhouse and the present. We investigated dispersed pollen using light and scanning electron microscopy. We assessed biogeographic patterns in Fagaceae during two warm periods in Earth history (MCO, Eocene) and the present. Eight species of Fagaceae were recognized in the Søby flora. Of these, Fagus had a continuous Mediterranean to subarctic distribution during MCO; Quercus sect. Cerris and castaneoids had northern limits in Denmark, and evergreen Quercus sect. Ilex in Central Europe. In a northern hemispheric context, Fagus and sections of Quercus had more northerly distribution limits during Eocene and MCO with maximum northward extensions during Eocene (Fagus, castaneoids) or Oligo-Miocene (Quercus sects. Cerris and Ilex). The known distribution of the extinct Tricolporopollenites theacoides during MCO included Central Europe and East China, while this taxon thrived in South China during Eocene. More northerly distributions during MCO and Eocene probably were determined by temperature. In contrast, fossil occurrences in areas that are arid or semi-humid today were determined by maritime conditions in these areas (western North America, Central Asia) during the Cenozoic.

Influence of May–June frontal precipitation on coherent moisture pattern in east-central China since 1793 based on tree-ring data

The short and scare record limits to understand the history of the hydroclimate change in east-central China. In this study, we developed a 225-year tree-ring width chronology (STD) for Chinese pine originating from the Shiren Mountain in Henan Province, east-central China. We analysed the correlation between the STD and different climatic factors and then reconstructed the May–June moisture variation, which is one of the longest moisture variation reconstruction based on tree-ring width in this region. Further, the results of the spatial analysis between our reconstruction and actual moisture variation revealed that our reconstruction is representative of large-scale May–June self-calibrating Palmer Drought Severity Index (scPDSI) in east-central China. Additionally, the reconstruction showed five relatively dry and five relatively wet epochs over the past 225 years. It also showed that the moisture variation in the study area is similar to those corresponding to other nearby sites and could be validated by historical documents; these findings demonstrate the reliability of our reconstruction back in time. Furthermore, we detected the reason for the coherent May–June moisture change in east-central China. It showed that the actual scPDSI showed significantly positive correlations with concurrent precipitation. Additionally, regression analyses showed that precipitation is largely determined by the frontal system, which is also responsible for the coherent May–June moisture pattern observed in east-central China. In addition, the result of spectral analysis and correlation patterns of the reconstructed scPDSI with global sea surface temperatures indicated that the El Niño-Southern Oscillations might be the forcing mechanism for regional moisture variability.

GDGTs-based quantitative reconstruction of water level changes and precipitation at Daye Lake, Qinling Mountains (central-east China), over the past 2000 years

Alpine lakes are natural rain gauges, and reconstructing changes in their water level is a key to understanding the regional hydrological environment, climate change and vegetation evolution. Precipitation in the northern and the southern parts of the eastern monsoon region of China exhibits a centennial-scale inverse relationship over the past 2000 years; however, there is substantial uncertainty regarding the temporal range of this dipolar pattern. In order to better understand this north-south pattern of precipitation variation and its driving mechanism, we analyzed isoGDGTs biomarker compounds in a sediment core from alpine Daye Lake, in the Qinling Mountains, in the north-south climatic transition zone of eastern China. Measurements of %Cren were used to reconstruct changes in lake level over the past 2000 years. The results show that, from 240 to 1300 CE, prior to the Little Ice Age, the lake-level changes were consistent with the precipitation record for the northern part of eastern China, with the lake reaching its highest level of 25 ± 7.17 m at 555 CE; subsequently, the lake fell to its lowest level of 12 ± 7.17 m at 1030 CE. During the Little Ice Age, the water level maintained an increasing trend, especially during the last three centuries, when it remained above 20 ± 7.17 m, which is consistent with the precipitation record from southern China. The results indicate that the climatically transitional Qinling region has a complex history of climate change. During the early part of the record (240–1300 CE), the level of Daye Lake and the East Asian summer monsoon precipitation were in phase, controlled mainly by the strength of the East Asian summer monsoon. In contrast, since the Little Ice Age (1300 CE to the present), under the influence of ENSO, the westward extension and southward retreat of the West Pacific Subtropical High caused the rain belt to shift southward, decreasing the water vapor supply to the Qinling Mountains. The ascent of moisture-bearing air over the Qinling Mountains resulted in orographic rainfall, while the weakening of evaporation during the Little Ice Age reduced the evaporation of water vapor and also contributed to the continued rise of the level of Daye Lake. The abundant precipitation in the Qinling region during the Little Ice Age provided water resources to sustain human activities in the downstream Weihe Plain, but was also a major cause of flooding.

Light-absorption properties of brown carbon aerosols in the Asian outflow: Implications of a combination of filter and ground remote-sensing observations at Fukue Island, Japan

Brown carbon (BrC) aerosols have important warming effects on Earth's radiative forcing. However, information on the evolution of the light-absorption properties of BrC aerosols in the Asian outflow region is limited. In this study, we evaluated the light-absorption properties of BrC using in-situ filter measurements and sky radiometer observations of the ground-based remote sensing network SKYradiometer NETwork (SKYNET) made on Fukue Island, western Japan in 2018. The light-absorption coefficient of BrC obtained from filter measurements had a temporal trend similar to that of the ambient concentration of black carbon (BC), indicating that BrC and BC have common combustion sources. The absorption Angstrom exponent in the wavelength range of 340–870 nm derived from the SKYNET observations was 15% higher in spring (1.81 ± 0.30) than through the whole year (1.53 ± 0.50), suggesting that the Asian outflow carries light-absorbing aerosols to Fukue Island and the western North Pacific. After eliminating the contributions of BC, the absorption Angstrom exponent of BrC alone obtained from filter observations had a positive Spearman correlation (rs = 0.77, p < 0.1) with that derived from SKYNET observations but 33% higher values, indicating that the light-absorption properties of BrC were successfully captured using the two methods. Using the atmospheric transport model FLEXPART and fire hotspots obtained from the Visible Infrared Imaging Radiometer Suite product, we identified a high-BrC event related to an air mass originating from regions with consistent fossil fuel combustion and sporadic open biomass burning in central East China. The results of the study may help to clarify the dynamics and climatic effects of BrC aerosols in East Asia.

Impacts of haze pollution on China's tourism industry: A system of economic loss analysis

Haze pollution not only negatively influences public health but also causes great economic losses. However, most previous studies have mainly focused on health-related economic losses, while the negative effects of haze pollution on the tourism industry are often ignored, leading to the unsustainable development of tourism. In this context, contrasting with previous research perspectives, this article selected several representative tourist cities from East China, South China, Central China, North China, Northwest China, Southwest China, and Northeast China as research objects in an empirical study, developing an economic loss analysis system to quantitatively evaluate the losses in the tourism industry caused by haze pollution. This system uses the satin bower bird optimization-based distribution estimation method to identify the optimal distribution of haze pollution, demonstrating superior performance to the traditional estimation method. Meanwhile, the optimal distribution of haze pollution is employed to measure the probability of different concentration limits in each area. Furthermore, the economic loss formula of the tourism industry is proposed in the devised system, calculating the economic loss caused by haze pollution at different degrees. The results show that haze pollution in different degrees has caused varying degrees of losses to China's tourism industry. In terms of seasonality and regionality, different seasons and different regions produce different results. Compared with summer, autumn and winter haze pollution is more severe, creating obvious seasonal differences. There is also a regional agglomeration effect, whereby the regional distribution of haze pollution is consistent with each region's economic development.

A skillful prediction scheme for April precipitation over central East China

Central East China (30°N–42°N, 105°E–122°E), around the lower and middle reaches of the Yangtze River valley to north China, is one of the main agricultural bases over East Asia. Spring precipitation can significantly influence the regional agricultural activity and production, such as the crop planting and winter wheat growing over the region. Here, we find that different from the March and May precipitation over central East China, the April precipitation there shows relatively weak relationships with the preceding El Niño-Southern Oscillation (ENSO) and Indian Ocean basin mode (IOB) which are usually used as the prediction signals. Therefore, in this study, from the perspective of the prediction, we identify two predictors in the preceding months for the variability in the April precipitation over central East China: (1) the sea surface temperature (SST) over the subtropical North Atlantic in January and (2) the snow cover around the region to the east of Lake Baikal in March. The anomalous SST signal shows a good persistence from January to April, and further stimulates a wave train propagating from the subtropical North Atlantic eastward to East Asia during April, which could contribute to an anomalous East Asian trough and thereby the precipitation anomalies over central East China. The anomalous snow cover signal in March also tends to persist to the following April, and the associated anomalous cooling/warming could exert an impact on the East Asian trough, consequently influencing the April precipitation over central East China. Based on the two predictors, we establish a statistical prediction scheme and further evaluate its predictive skills. The results suggest the potential of the scheme for the prediction of the April central East China precipitation.

Alterations in the human oral and gut microbiomes and lipidomics in COVID-19

ObjectiveTo characterise the oral microbiome, gut microbiome and serum lipid profiles in patients with active COVID-19 and recovered patients; evaluate the potential of the microbiome as a non-invasive biomarker for...

Assessment of the effects of straw burning bans in China: Emissions, air quality, and health impacts

Open biomass burning (OBB) plays an important role in air pollution and climate change by releasing short-term but intensive amounts of particulate matter and gaseous air pollutants. During past years, policies with respect to prohibition on open straw burning have been issued in China in order to mitigate the air pollution problems and the effectiveness of these straw burning bans in different regions remains to be evaluated. In this study, open crop straw burning (OCSB) emissions during 2010–2018 were analyzed based on a commonly used emission inventory with high spatial and temporal resolution. High emissions concentrated over Northeast China (31.8% of national total PM2.5 emissions in 2018), East China (24.0%), and North China (16.6%). Simulations based on an integrated meteorology-air quality modeling system and an exposure-response function show that OCSB emissions could increase monthly PM2.5 concentration by as much as 10 μg/m3 during burning seasons in Northeast China and were associated with 4741 premature deaths in 2018. Spatial heterogeneities were observed with respect to the trends of OCSB emissions during 2010–2018. In East China, North China, and Central China, OCSB emissions showed a general declining trend since 2013 while an opposing increasing trend was observed in Northeast China with peak emissions in 2017. Comparing 2013 (before intensive implementation of straw burning bans) and 2018 (after), national total PM2.5 emissions from OCSB activities decreased by 46.9%, ranging from −14.1% to +70% depending on the specific regions. Northeast China is the only region that showed higher OCSB emissions in 2018 compared to 2013, probably associated with the relatively delayed implementation of the straw burning bans. Avoided number of premature deaths due to reduced OCSB emissions was estimated to be 4256 on a national scale, with most health benefits gained in East and Central China. Results from this study demonstrate the importance of OCSB contribution to PM2.5 concentrations and spatial heterogeneities exist in terms of the effectiveness of the straw burning bans in reducing OCSB emissions and gained health benefits.

&lt;strong&gt;&lt;em&gt;Allium yingshanense&lt;/em&gt;, a new species from the Dabie Mountains (east-central China), and taxonomic remarks on the related species&lt;/strong&gt;

Allium yingshanense, a new late-flowering diploid species (2n = 16), is described from the Dabie Mountains (east-central China). It grows on moist rock slopes along river banks in forests or rocky cliffs with an aggregated distribution. Morphologically, it is distinctly different from all known species of the Chinese Allium by its outer and inner filaments with 1-toothed on each side, which is fairly rare in the entire genus Allium, suggesting it is an independent species. The ITS phylogenetic analysis further reveals that the new species is most closely related to A. longistylum and A. flavovirens, which is also highly congruent with their overall morphological and chromosomal similarities, supporting placing the new species into A. subg. Cepa according to the current infrageneric classification of Allium. It is easily distinguished from A. longistylum and A. flavovirens particularly by filaments, inner and outer tepal characters at the specific level. Additionally, A. longistylum is proven to be endemic to China and morphologically quite different from the Korean ‘A. longistylum’ in bulb, leaf and floral characteristics, and not a member of A. sect. Sacculiferum or sect. Condensatum formerly suggested. The inclusion of the new species A. yingshanense along with A. longistylum into the newly proposed A. sect. Flavovirens typified by A. flavovirens, although possible from our data, as well as the formal description of the section seem premature especially given that there is substantial incongruence between taxonomy and molecular phylogeny of A. subg. Cepa.

The factors of regional PM2.5 emissions inequality in China

Since the reform and opening up, China's economy has developed rapidly, which has also caused environmental problems such as industrial emissions. PM2.5 (particulate matter with a diameter of less than 2.5 microns) emissions seriously threaten people's health. Therefore, it is necessary to study the emission reduction of PM2.5. This study combines the Data Envelopment Analysis (DEA) and Logarithmic Mean Divisia Index (LMDI) methods to originally construct the inequality indicator and explore the influence of different factors on the inequality of per capita PM2.5 from the regional aspect. This study decomposes the “emission efficiency” of per capita PM2.5 emissions into more important effects. It reveals that, in East China, the energy-oriented technology gap (ETG) had the strong reducing effect on the national per capita PM2.5 emissions; the energy-oriented technology efficiency (ETE) and economic development level (EDL) had the strong promoting effect. In Central China, the potential emission intensity (PEI) has the strong reducing effect on the national per capita PM2.5 emissions, followed by the EDL; the ETG and energy-biased technology (EBT) effect had the strong promoting effect. In West China, the ETE had the strong reducing effect on the national per capita PM2.5, followed by the PEI; the ETG had the strong promoting effect, followed by the EBT and output-oriented technology gap (YTG). The ETE had the greatest improving effect on the inequality indicator, and the PEI and EDL had the greatest reducing effect. Policy suggestions are put forward based on regional differences in East China, Central China and West China.

P and S wave tomography of east-central China: insight into past and present mantle dynamics

East-central China has experienced multi-stage evolution among different tectonic units; thus the present geological structures are superimposed in a long history. But it is still unclear how different tectonic processes interact with each other, especially how the subsequent activity affects the previous structures. In this study, we determined new high-resolution P and S wave tomography of the upper mantle beneath the east-central China. We imaged the stagnant Pacific slab in the mantle transition zone and the hot low-velocity upper mantle in eastern China while cold high-velocity bodies beneath the Archean cratons in central China. More importantly, we newly revealed two important features. Firstly, a high-velocity zone is found in the uppermost mantle (50–150 km) beneath the Southeast China; its location is comparable to the distribution of the Cretaceous igneous rocks. Thus, we propose that the high-velocity anomalies reflect the remnant mafic rocks in the upper mantle after the volcanic eruption. Secondly, a high-velocity body is revealed in the deep upper mantle (300–500 km) beneath the southwestern Yangtze craton, possibly implying the delaminated cratonic lithosphere in the Early Mesozoic.