Extreme haze episodes repeatedly shrouded Beijing during the winter of 2012–2013, causing major environmental and health problems. To better understand these extreme events, particle number size ...distribution (PNSD) and particle chemical composition (PCC) data collected in an intensive winter campaign in an urban site of Beijing were used to investigate the sources of ambient fine particles. Positive matrix factorization (PMF) analysis resolved a total of eight factors: two traffic factors, combustion factors, secondary aerosol, two accumulation mode aerosol factors, road dust, and long-range transported (LRT) dust. Traffic emissions (54 %) and combustion aerosol (27 %) were found to be the most important sources for particle number concentration, whereas combustion aerosol (33 %) and accumulation mode aerosol (37 %) dominated particle volume concentrations. Chemical compositions and sources of fine particles changed dynamically in the haze episodes. An enhanced role of secondary inorganic species was observed in the formation of haze pollution. Regional transport played an important role for high particles, contribution of which was on average up to 24–49 % during the haze episodes. Secondary aerosols from urban background presented the largest contributions (45 %) for the rapid increase of fine particles in the severest haze episode. In addition, the invasion of LRT dust aerosols further elevated the fine particles during the extreme haze episode. Our results showed a clear impact of regional transport on the local air pollution, suggesting the importance of regional-scale emission control measures in the local air quality management of Beijing.
We quantify for the first time marine aerosol properties and their differences in the offshore and remote ocean in the mid-latitude South Asian waters, low-latitude South Asian waters, and equatorial ...waters of the Western Pacific Ocean, based on shipboard cruise observations conducted by the Western Pacific Ocean Scientific Observation Network in winter 2018, and further investigate the effects of long-range transport of continental aerosols on the marine environment. During the overall observation period, the average number concentration of particle matter which aerodynamic diameters<2.5 μm (PM2.5N) was 35.1 ± 87.4 cm−3 and the mass concentration (PM2.5M) was 12.3 ± 9.1 μg/m3. The PM2.5N and PM2.5M during the continental air mass transport period were 7.2 and 1.3 times higher than those during the non-transport period (109.2 ± 169.3 cm−3, 15.9 ± 14.9 μg/m3), respectively. Excluding transport period, the average PM2.5N and PM2.5M are reduced by 120% and 7%. Coarse mode particle number concentration (PM2.5–10N) and mass concentration (PM2.5–10M) are not significantly influenced by continental air masses (only a reduction of 7% and 2%). The variation of marine aerosol concentrations in different latitudes zones is greatly influenced by continental aerosol transport. The offshore PM2.5M/PM10M was 30%, 21%, and 22% in the mid-latitude sea of South Asia, a low-latitude sea of South Asia, and the equatorial sea, respectively. In comparison, in the remote ocean, the distribution ratio of PM2.5M/PM10M tended to be steady (22%–23%), and the background characteristics of marine aerosols were clearly represented. The aerosol concentration decreases with the increase of wind speed during the transport period, and the wind speed reflects the scavenging effect on aerosol. In the non-transport period, the wind speed at the sea surface promotes the generation of marine aerosols, and the impact in wind speed is strongest in the PM2.5–PM5 particle size range.
Schematic diagram of the distribution of aerosols in the western Pacific Ocean at different latitudes and offshore distance. The pie chart represents the particle size composition of different latitudinal zones. Display omitted
•Large differences in aerosol distribution between near-land and open-ocean area.•Continental transport lead to increase in the proportion of fine particles.•Continental transport affects near-land aerosol distribution to varying degrees.•Different wind speed responses to transport and non-transport period.
Under a high atmospheric oxidization capacity, the synergistic effect of the physicochemical processes in the atmospheric boundary layer (ABL) caused summer haze pollution in Beijing. The southern ...and southwestern areas, generally 60–300 km away from Beijing, were seriously polluted in contrast to Beijing, which remained clean. Southerly winds moving faster than 20–30 km h−1 since the early morning primarily caused haze pollution initiation. The PM2.5 (particulate matter with a dynamic equivalent diameter smaller than 2.5 µm) level increased to 75 µg m−3 over several hours during the daytime, which was simultaneously affected by the ABL structure. Additionally, the O3 concentration was quite high during the daytime (250 µg m−3), corresponding to a high atmospheric oxidation capacity. Much sulfate and nitrate were produced through active atmospheric chemical processes, with sulfur oxidation ratios (SORs) up to ∼0.76 and nitrogen oxidation ratios (NORs) increasing from 0.09 to 0.26, which further facilitated particulate matter (PM) level enhancement. However, the increase in sulfate was mainly linked to southerly transport. At midnight, the PM2.5 concentration sharply increased from 75 to 150 µg m−3 over 4 h and remained at its highest level until the next morning. Under an extremely stable ABL structure, secondary aerosol formation dominated by nitrate was quite intense, driving the haze pollution outbreak. The PM levels in the southern and southeastern areas of Beijing were significantly lower than those in Beijing at this time, even below air quality standards; thus, the contribution of pollution transport had almost disappeared. With the formation of a nocturnal stable boundary layer (NSBL) at an altitude ranging from 0–0.3 km, the extremely low turbulence kinetic energy (TKE) ranging from 0 to 0.05 m2 s−2 inhibited the spread of particles and moisture, ultimately resulting in elevated near-surface PM2.5 and relative humidity (∼90 %) levels. Due to the very high humidity and ambient oxidization capacity, NOR rapidly increased from 0.26 to 0.60, and heterogeneous hydrolysis reactions at the moist particle surface were very notable. The nitrate concentration steeply increased from 11.6 to 57.8 µg m−3, while the sulfate and organics concentrations slightly increased by 6.1 and 3.1 µg m−3, respectively. With clean and strong winds passing through Beijing, the stable ABL dissipated with the potential temperature gradient becoming negative and the ABL height (ABLH) increasing to ∼2.5 km. The high turbulence activity with a TKE ranging from 3 to 5 m2 s−2 notably promoted pollution diffusion. The self-cleaning capacity of the atmosphere is commonly responsible for air
pollution dispersion. However, reducing the atmospheric oxidization
capacity, through strengthening collaborative control of nitrogen oxide
(NOx) and volatile organic compounds (VOCs), as well as continuously deepening regional joint air pollution control, is urgent.
KEY MESSAGE : SNP-based QTL mapping provided useful information for novel loci that can be used in breeding programs to control tillering and improve yield in wheat via marker-assisted selection. ...Tillering is one of the most important agronomic traits affecting biomass and grain yield potential in wheat. Wheat lines with very limited tillering capacity are more productive than free-tillering lines under severe drought conditions. In this study, three recombinant inbred line (RIL) populations were generated and used, having H461, a low-tillering genotype, as a common parent. A linkage map containing 7808 single nucleotide polymorphism loci was constructed on the basis of H461/CN16 RIL population. Three QTL controlling low tillering were identified on Chromosome (Chr.) 2D (Qltn.sicau-2D), Chr. 2B (Qltn.sicau-2B), and Chr. 5A (Qltn.sicau-5A). Qltn.sicau-2D, Qltn.sicau-2B, and Qltn.sicau-5A explained up to 19.1, 14.6, and 9.6 % of the phenotypic variance, respectively. Comparing with previous findings, Qltn.sicau-2D and Qltn.sicau-2B should thus be novel tillering QTL. The effects of these QTL were further validated in two additional RIL populations. Significant effects of Qltn.sicau-2D were detected across all growth stages in different genetic backgrounds, making it an ideal target for breeding programs as well as for further characterization of the gene(s) underlying this locus.
Leaf size is an important factor contributing to the photosynthetic capability of wheat plants. It also significantly affects various agronomic traits. In particular, the flag leaves contribute ...significantly to grain yield in wheat. A recombinant inbred line (RIL) population developed between varieties with significant differences in flag leaf traits was used to map quantitative trait loci (QTL) of flag leaf length (FLL) and to evaluate its pleiotropic effects on five yield-related traits, including spike length (SL), spikelet number per spike (SPN), kernel number per spike (KN), kernel length (KL), and thousand-kernel weight (TKW). Two additional RIL populations were used to validate the detected QTL and reveal the relationships in different genetic backgrounds. Using the diversity arrays technology (DArT) genetic linkage map, three major QTL for FLL were detected, with single QTL in different environments explaining 8.6–23.3% of the phenotypic variation. All the QTL were detected in at least four environments, and validated in two related populations based on the designed primers. These QTL and the newly developed primers are expected to be valuable for fine mapping and marker-assisted selection in wheat breeding programs.
In order to achieve the targets specified in the Action Plan for Air Pollution Prevention and Control (APAPPC), a limited coal banning area (10,000 km2) was designated in the heavily polluted ...Beijing-Tianjin-Hebei region (BTH) for the first time in 2017. PM2.5 and elements were sampled by the network of BTH to evaluate the effectiveness of this policy. This study found that the fine days with PM2.5 < 75 μg m−3 accounted for 74.3% in the autumn and winter of 2017, which was significantly higher than that in 2016 (43%). The heavily polluted days (PM2.5 > 150 μg m−3) also decreased from 32.2% in 2016 to 4.9% in 2017. Arsenic (As) is an important tracer in coal consumption, which can be used to reflect the influence of the establishment of coal banning areas on north China. The cluster analysis of air mass forward trajectory identified that the number of polluted trajectories with PM2.5 and As in 2017 decreased by 47.6% and 49.7%, respectively. Under the implementation of the coal banning policy, the weighted concentration of PM2.5 and As decreased by 94.2 μg m−3 and 5.1 ng m−3 in the coal banning area, 60.9 μg m−3 and 3.4 ng m−3 in the no coal banning area in BTH, respectively. The influence of weighted concentration of PM2.5 and As in coal banning area on North China were 1.6–49.2 μg m−3 and 0.15–2.8 ng m−3, respectively, which was 38.8% and 29.7% lower than 2016. In coal banning area, BTH and other parts of North China, the reduction of the weight concentration of PM2.5 in 2017 accounted for 41.4%, 26.8% and 31.8% of the total reduction, respectively, so was the As in 39%, 26.3% and 34.6%, indicating that setting up a coal banning area scientifically in limited areas can produce remarkable regional benefit.
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•Coal banning area brought remarkable environmental benefit to the whole north China.•Fine days in the autumn and winter of BTH increased from 43% in 2016 to 74% in 2017.•Impact of PM2.5 in coal banning area (BTH) reduced by 94.2 (60.9) μg m−3 in 2017.•The impact of coal banning area on PM2.5 in North China decreased by 48.3% in 2017.
Fusarium crown rot (FCR) is a fungal disease and severely decreases wheat production worldwide. Tibetan semiwild wheat, Yunnan hulled wheat, Xinjiang rice wheat, and Sichuan white wheat are four ...subspecies landraces endemic to western China and have rich genetic diversity in response to biotic and abiotic stresses. Here, a natural population, including 209 wheat accessions of four subspecies, was evaluated for FCR resistance. he genome-wide association study was performed using the wheat 55K single-nucleotide polymorphisms (SNPs). The results showed that the disease index (DI) ranged from 16.88 to 85.00, while six accessions showed moderate to high resistance (DI ≤ 30). Genome-wide association analysis identified 10 stable loci for FCR resistance on chromosomes 1B, 2A (5), 5A, 7A, 7B, and 7D. Four major loci-
,
,
, and
-explained 6.01 to 14.48, 9.76 to 13.11, 8.19 to 10.29, and 5.76 to 12.21% phenotypic variation, respectively. Quantitative trait loci (QTL) pyramiding analysis of these four major loci revealed that accessions with four resistance haplotypes could significantly decrease FCR severity by 9.35 to 31.61% compared with those without or with one to three resistance haplotypes. One kompetitive allele-specific PCR (KASP) marker each was successfully developed for
and
. The KASP marker of
was used to genotype in an F
recombinant inbred line population. The result showed that the lines carrying the resistance allele reduced FCR severity by 17.78%, demonstrating the importance of
in resistance breeding programs. Our findings provide valuable QTL and breeder-friendly PCR-based markers for applications in FCR resistance breeding programs. Our study also proved that gene pyramiding of major loci could enhance FCR resistance.
The high-resolution dynamic, thermal and material structures of sea-land breeze circulation (SLB) were observed at the coastal of Ningbo, East China Sea from November 2019 to May 2020, with wind ...profile lidar, microwave radiometer and particulate matter lidar. The results show that SLB occurs more frequently in spring (22 days) than in winter (18 days). The horizontal wind speed is generally less than 8 m·s−1, and the vertical wind speed is less than 0.17 m·s−1. The maximum U wind component is 3.2 m·s−1 and 2.4 m·s−1 in spring and winter, respectively. The U wind component and its gradient show that the circulation heights of sea breeze in winter and spring are 1.3 km and 1.8 km, respectively. The heights of land breeze (LB) in winter and spring are 0.65 km and 1.1 km, respectively. The horizontal wind speed shows that the prevailing heights of sea breeze (SB) in winter and spring are 0.9 km and 1.3 km, respectively. The prevailing heights of LB in winter and spring are 0.4 km and 0.7 km, respectively. The boundary layer height during SB is about 1.1 km, and the residual layer height during LB is about 0.6 km at night. The development of SLB in winter is obviously different from that in spring, the transition process is about 2 h shorter than that in spring. With the rapid change of wind speed and direction, the turbulent kinetic energy reaches 3.5m2·s−2 on about 1.0–1.2 km in the circulation. The maximum of TKE in spring is higher than that in winter. The changes of temperature and absolute humidity are similar in winter and spring. Particulate matter was confined within the boundary layer of SLB, much lower than the circulation height. When the SB speed increases, the PM10 concentration decreases. PM10 has a zonal distribution at 400 m in spring.
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•The prevailing sea breeze was 6.1 m·s−1 at 1.3 km height in spring and7.5 m·s−1 at 0.9 km height in winter.•The prevailing land breeze was 5.3 m·s−1 at 0.7 km height in spring and 6.6 m·s−1 at 0.4 km height in winter.•The maximum TKE reached 3.5 m2·s−2 at about 1–1.2 km height during the prevailing sea breeze.•The sea breeze was warmer than the land breeze for 4.3 K in spring and 3.7 K in winter at the same height in average.
Stripe rust is a destructive disease that affects plant growth and substantially reduces wheat yields globally. An economically and environmentally friendly way to control this disease is to use ...resistant cultivars. 'N2496' is a synthetic hexaploid wheat derivative that exhibits high resistance and could serve as a source of resistance for breeding programs. We developed three recombinant inbred lines (RILs) populations by crossing 'N2496' with common wheat cultivars 'CN16', 'CM107', and 'MM37'. Stripe rust responses were evaluated in all three populations using a mixture of current predominant Chinese
f. sp.
races. A stripe rust resistance quantitative trait locus (QTL) in the 'N2496'/'CN16' RIL population was mapped on chromosome arm 6BL at 519.35 to 526.55 Mb using bulked segregant RNA sequencing. The population was genotyped using simple sequence repeats and kompetitive allele-specific polymerase (KASP) markers. The QTL
was localized to a 1.19-cM interval flanked by markers
and
. The genetic effect of
was validated in the 'N2496' × 'CM107' and 'N2496' × 'MM37' RILs populations and explained up to 63.16% of the phenotypic variation. RNA sequencing and quantitative real-time polymerase chain reaction identified two differentially expressed candidate genes in the physical interval of
.
The concentration of secondary organic aerosol (SOA) is underestimated in
current model studies. Recent research suggests that the reactive uptake of
dicarbonyls contributes to the production of SOA, ...although few models have
included this pathway. Glyoxal, an important representative component of
dicarbonyls in models, is significantly underestimated. We therefore
incorporated the reactive uptake of dicarbonyls into the regional air
quality modeling system RAMS-CMAQ (the Regional Atmospheric Modeling
System-Community Multiscale Air Quality) to evaluate the contribution of
dicarbonyls to SOA, and we then assess the impact of the underestimation of
glyoxal on the production of SOA in China during two time periods: 3 June to
11 July 2014 (episode 1) and 14 October to 14 November 2014 (episode 2).
When the reactive uptake process was added, the modeled mean concentration
of SOA in episode 1 increased by 3.65 µg m−3, which explained
34.8 % of the unaccounted-for source of SOA. Meanwhile the increase in the
concentration of SOA in episode 2 was 1.82 µg m−3 as a result of
the lower liquid water content and the lower amount of dicarbonyls produced
from biogenic precursors in the fall. On this basis, when the glyoxal
simulation was improved, the modeled mean dicarbonyl-derived SOA
(AAQ)
increased by more than a factor of 2 in both episodes relative to case 1.
AAQ in episode 1 contributed, on average, 60.6 % of the total
concentration of SOA and the increase in this contribution represented
69.1 % of the unaccounted-for concentration of SOA, whereas the mean AAQ in
episode 2 accounted for 64.5 % of total concentration of SOA. Based on the
results, the mean AAQ over China was generally higher in the east than in
the west during the two episodes. The highest value (10–15 µg m−3)
of episode 1 appeared in the areas around the lower reaches of the Yellow
River, whereas the highest value of 5–10 µg m−3 in episode 2 was
concentrated over regions from south of the lower reaches of the Yellow
River to the south of Guangzhou Province as well as the Sichuan Basin. The
contribution of AAQ to the concentration of SOA in episode 1 varied from
10 %
to 90 % throughout China, with the highest contributions (70 %–90 %) in
the coastal regions and offshore along the East China Sea to the South China
Sea and in the southwestern regions. The fraction of AAQ to SOA in
episode 2 was in the range of 10 %–80 % over China, with the fraction up to
80 % in a small portion of northeastern China.
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