Deficiency of available phosphorus (P) in soil limits wheat production and creates a need to develop P-deficiency-tolerant cultivars. Plant roots, important organs for absorbing nutrients and ...synthesizing growth regulators, are good candidates for P-efficiency screening. In this study, we evaluated five root traits under hydroponic culture conditions either with (AP) or without (NP) applied P in a recombinant inbred line population (H461/CM107) of Triticum aestivum L. at the seedling stage. Four significant quantitative trait loci (QTL) were detected, on chromosomes 1D, 2D, 3D, and 7D in NP-treated plants, explaining up to 13.0%, 11.0%, 14.4%, and 12.8% of the phenotypic variance, respectively. Among these QTL, Qrt.sicau-3D and Qrt.sicau-7D showed pleiotropic and additive effects. All QTL were found to be novel. The diversity array technology markers flanking the QTL were converted to simple sequence repeat markers that can be deployed in future genetic studies of P deficiency. These QTL lead to an increase in root biomass and respond to P-deficiency stress; these characteristics are crucial to improve root traits for breeding or further investigation of the gene(s) involved in P-deficiency tolerance.
Synthetic hexaploid wheat (SHW) possesses numerous genes for resistance to stress, including phosphorus (P) deficiency. Root diameter (RDM) plays an important role in P-deficiency tolerance, but ...information related to SHW is still limited. Thus, the objective of this study was to investigate the genetic architecture of RDM in SHW under P-deficient conditions. To this end, we measured the RDM of 138 F
9
recombinant inbred lines derived from an F
2
population of a synthetic hexaploid wheat line (SHW-L1) and a common wheat line (Chuanmai32) under two P conditions, P sufficiency (PS) and P deficiency (PD), and mapped quantitative trait loci (QTL) for RDM using an enriched high-density genetic map, containing 120,370 single nucleotide polymorphisms, 733 diversity arrays technology markers, and 119 simple sequence repeats. We identified seven RDM QTL for P-deficiency tolerance that individually explained 11–14.7% of the phenotypic variation. Five putative candidate genes involved in root composition, energy supply, and defense response were predicted. Overall, our results provided essential information for cloning genes related to P-deficiency tolerance in common wheat that might help in breeding P-deficiency-tolerant wheat cultivars.
Difference and uncertainty of the aerosol radiative effects were quantified using the Santa Barbara DISORT Atmospheric Radiative Transfer model and multiple aerosol observation data sets from ...urban‐forest transition region. The secondary transformed carbonaceous aerosol components and biogenic secondary organic aerosol (BSOA) tracers have dominated over all other components (with a higher concentration in wet season) in terms of its impact on the aerosol radiative forcing (ARF). The averaged organic carbon (OC) and BSOA tracers increased from 13.3 ± 4.99 μg/m3, 29.5 ± 10.7 ng m−3 to 17.3 ± 4.47 μg/m3, 78.7 ± 43.7 ng m−3 in the dry and wet seasons, respectively. The corresponding root mean square errors of single scattering albedo and radiative forcing at the top of the atmosphere have increased by 8.4% and 16.9%. From the dry season to the wet season, the drastically aerosol composition and types variations caused the aerosol radiation effect reverse from cooling to heating. The increase in carbonaceous aerosols and BSOA transformed by forests in the wet season weakened the cooling effects. Driven by multiple factors, such as meteorological conditions, emission sources, and the mixed state of particulate matters, the transport patterns of air masses exhibit completely opposite effects to the ARF. Affected by the source location, wet deposition rate and components residence time, the uncertainty of ARF caused by long‐distance transport of aerosols is 68% higher than that of local aerosol situations under the condition of similar aerosol composition distributions. At similar transport distances, stronger aerosol secondary transformation increases the uncertainty of ARF by 20%.
Plain Language Summary
Aerosol components have their ubiquitous nature and ability to mix with other aerosol types and affected by transport and deposition, increasing a bias in the estimation of aerosol radiative forcing. In this study, we demonstrated this potential impact from a measurement‐based perspective in a typical transition region in East China with abundant biogenic secondary organic aerosol emissions and quantified the uncertainty of the aerosol radiative forcing (ARF) caused by variations in aerosol composition. Different aerosol components will lead to the reversal of aerosol radiation effects in different seasons, and the increase in the proportion of secondary transformed aerosols will cause large uncertainty in ARF. Driven by multiple factors, aerosol transport distance also has a significant effect on uncertainties of ARF.
Key Points
The aerosol properties and radiative effects show greatly seasonal differences over urban‐forest transition region in East China
The differences of the aerosol components and secondary species transformation lead to obviously aerosol radiative forcing (ARF) uncertainties
Driven by meteorological conditions, emission source and the persistent state of particulate matter, aerosol transport distance has a significant effect on uncertainties of ARF
The implementation of emission reduction measures during the Olympics provided a valuable opportunity to study regional photochemical pollution over northern China. In this study, the ...fifth-generation Pennsylvania State University/National Centre for Atmospheric Research Mesoscale Model and Community Multiscale Air Quality model system was applied to conduct two sets of modelling analyses of the period from July 20 to September 20, 2008, to illustrate the influences of emission reduction measures on regional photochemical pollution over northern China during the Beijing Olympics. The results indicated that the implementation of emission control measures decreased the concentrations of ozone (O3) precursors, namely nitrogen oxide (NOx) and volatile organic compounds (VOCs), throughout the boundary layer. The concentrations of these compounds were reduced by 45% in the central urban area of Beijing at the ground level. Although the average O3 concentration in the central urban area increased by more than 8ppbv, the total oxidant concentration decreased significantly by more than 5ppbv. Greater O3 concentrations mainly occurred during periods with weak photochemical reactions. During periods of strong photochemical production, the O3 concentration decreased significantly due to a weakening vertical circulation between the lower and upper boundary layer. Consequently, the number of days when the O3 concentration exceeded 100ppbv decreased by 25% in Beijing. The emission control measures altered the sensitivity of the regional O3 production. The coordinated control region of NOx and VOCs expanded, and the control region of VOCs decreased in size. The reduction of non-point-source emissions, such as fugitive VOCs and vehicles, was more useful for controlling regional photochemical pollution over northern China.
•Emission reductions had a nonlinear effect on O3.•O3 decreased during the day and increased at night.•O3 exceedances decreased by 25% in Beijing during the Olympics.•Reductions in non-point emissions were more useful for controlling O3 exceedances.
The simultaneous observation and analysis of atmospheric fine particles (PM.sub.2.5) on a regional scale is an important approach to develop control strategies for haze pollution. In this study, ...samples of filtered PM.sub.2.5 were collected simultaneously at three urban sites (Beijing, Tianjin, and Shijiazhuang) and at a regional background site (Xinglong) in the Beijing-Tianjin-Hebei (BTH) region from June 2014 to April 2015. The PM.sub.2.5 at the four sites was mainly comprised of organic matter, secondary inorganic ions, and mineral dust. Positive matrix factorization (PMF) demonstrated that, on an annual basis, secondary inorganic aerosol was the largest PM.sub.2.5 source in this region, accounting for 29.2-40.5 % of the PM.sub.2.5 mass at the urban sites; the second-largest PM.sub.2.5 source was motor vehicle exhaust, particularly in Beijing (24.9 %), whereas coal combustion was also a large source in Tianjin (12.4 %) and Shijiazhuang (15.5 %), with particular dominance in winter. Secondary inorganic aerosol plays a vital role in the haze process, with the exception of the spring haze in Shijiazhuang and Tianjin, for which the dust source was crucial. In addition to secondary transformations, local direct emissions (coal combustion and motor vehicle exhaust) significantly contribute to the winter haze at the urban sites. Moreover, with the aggravation of haze pollution, the OC â EC mass ratio of PM.sub.2.5 decreased considerably and the nitrate-rich secondary aerosol increased during all four seasons in Beijing, both of which indicate that local motor vehicle emissions significantly contribute to the severe haze episodes in Beijing. To assess the impacts of regional transport on haze pollution, the PMF results were further processed with backward-trajectory cluster analysis, revealing that haze pollution usually occurred when air masses originating from polluted industrial regions in the south prevailed and is characterized by high PM.sub.2.5 loadings with considerable contributions from secondary aerosols. This study suggests that control strategies to mitigate haze pollution in the BTH region should focus on the reduction of gaseous precursor emissions from fossil fuel combustion (motor vehicle emissions in Beijing and coal combustion in Tianjin, Hebei, and nearby provinces).
Land–sea breeze (LSB) is an atmospheric mesoscale circulation that occurs in the vicinity of the coast and is caused by uneven heating resulting from the difference in specific heat capacity between ...the sea and land surfaces. The circulation structure of LSB was quantitatively investigated with a Doppler wind lidar Windcube100s on the west coast of the Yellow Sea for the first time. The time of observation was 31 August to 28 September 2018. It was found that the height of LSB development was 700 m to 1300 m. The duration of conversion of LSB was between 6 h and 8 h. The biggest average horizontal sea-breeze wind speed at 425 m was 5.6 m s−1, and at 375 m it was 4.5 m s−1. During the conversion process from sea breeze to land breeze, the maximum wind shear exponent was 2.84 at 1300 m altitude. During the conversion process from land breeze to sea breeze, the maximum wind shear exponent was 1.28 at 700 m altitude. The differences in wind shear exponents between sea-breeze and land-breeze systems were between 0.2 and 3.6 at the same altitude. The maximum value of the wind shear exponent can reflect the height of LSB development.
摘要
陆海风是由于海陆表面之间的比热容不同而导致的昼夜热量分布差异, 从而在海岸附近引发的大气中尺度循环系统.本文利用多普勒风激光雷达Windcube100s首次对黄海西海岸的海陆风的循环结构进行了观测研究.在2018年8月31日至9月28日观测期间发现, 海陆风发展高度一般在700 m至1300 m.海陆风转化持续的时间为6小时至8小时.在425m高度, 海风水平风速出现最大值, 平均为 5.6 m s−1.陆风最大水平风速出现在370 m, 约为4.5 m s−1.最大风切变指数在1300m处, 为2.84;在陆风向海风转换过程中, 最大风切变指数在700m处, 为1.28.在同一高度上, 风切变指数在海风盛行和陆风盛行时的差值范围为0.2–3.6, 风切变能反映出海陆风的发展高度.
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Based on a shipboard observation conducted in winter 2018, we reported the aerosol chemical properties and their differences in offshore and remote oceans over the Western Pacific Ocean (WPO). It's ...found that the chemical compositions over the WPO have significant spatial heterogeneity due to the influences of regional transport of anthropogenic aerosols and long‐path transport of dust aerosols. The average concentration of water soluble ions during the whole sampling period followed Cl− > OC > Na+ > SO42− ${{\text{SO}}_{4}}^{2-}$ > NO3− ${{\text{NO}}_{3}}^{-}$ > Ca2+ > Mg2+ > EC > K+ > NH4+ ${{\text{NH}}_{4}}^{+}$. Crustal elements of Ca (980.41 ng/m3), Na (971.55 ng/m3), and Al (781.16 ng/m3) were uniformly distributed in offshore area, but high proportion of Na elements dominated in remote regions. The total concentration of heavy metals including Zn, Cu, Cr, Pb and others originating from anthropogenic sources were 208 ng/m3 along the coastal region, about 10 times higher than that of 20.2 ng/m3 in the offshore and remote seas. For the reconstructed components, we found an increase of sea‐salt aerosol ranged from 3% to 72%, and a decrease of black carbon, organic matter and secondary inorganic salts, indicating a transformation from anthropogenic influence to marine environment. The rapidly increased secondary organic matter during dust event revealed that the transport of dust serves as catalysts to promote multi‐phase reactions. Cl− photochemical reaction rate in offshore area was mainly affected by sulfate from anthropogenic emissions, with an average chlorine loss rate of 18%, whereas it was inverse Cl− excess in the remote oceans.
Plain Language Summary
The Institute of Oceanography, Chinese Academy of Sciences, organized a shipboard scientific observation over the Western Pacific Ocean (WPO) in winter 2018 to explore the chemical compositions of marine aerosols. The results showed that the chemical compositions over the WPO have significant spatial heterogeneity due to the different pollutants from various sources. Anthropogenic elements such as SO42− ${{\text{SO}}_{4}}^{2-}$, NO3− ${{\text{NO}}_{3}}^{-}$, and OC dominated in offshore waters, whereas the sea salt components of Na and Cl took a high proportion in remote oceans. In addition, dust aerosol originating from the North Africa also affected the WPO regions by long‐distance transport. The photochemical reaction rate of Cl− in offshore area was mainly affected by sulfate concentration from anthropogenic emissions, with an overall chlorine loss rate of 18%, but it exhibited an inversely Cl− excess phenomenon in the remote oceans.
Key Points
The compositions of aerosol presented a significant change from anthropogenic source to marine sea salt from coast to remote oceans
Dust from North Africa acted as catalyst to promote the intensive formation of secondary organic aerosols in equatorial area
There was a significant chlorine loss in the offshore coast, and a pronounced chlorine excess in remote seas
Currently, modeling studies tend to significantly underestimate observed space-based glyoxal (CHOCHO) vertical column densities (VCDs), implying the existence of missing sources of glyoxal. Several ...recent studies suggest that the emissions of aromatic compounds and molar yields of glyoxal in the chemical mechanisms may both be underestimated, which can affect the simulated glyoxal concentrations. In this study, the influences of these two factors on glyoxal amounts over China were investigated using the RAMS-CMAQ modeling system for January and July 2014. Four sensitivity simulations were performed, and the results were compared to satellite observations. These results demonstrated significant impacts on glyoxal concentrations from these two factors. In case 1, where the emissions of aromatic compounds were increased three-fold, improvements to glyoxal VCDs were seen in high anthropogenic emissions regions. In case 2, where molar yields of glyoxal from isoprene were increased five-fold, the resulted concentrations in July were 3–5-fold higher, achieving closer agreement between the modeled and measured glyoxal VCDs. The combined changes from both cases 1 and 2 were applied in case 3, and the model succeeded in further reducing the underestimations of glyoxal VCDs. However, the results over most of the regions with pronounced anthropogenic emissions were still underestimated. So the molar yields of glyoxal from anthropogenic precursors were considered in case 4. With these additional mole yield changes (a two-fold increase), the improved concentrations agreed better with the measurements in regions of the lower reaches of the Yangtze River and Yellow River in January but not in July.
There are underestimations in the modeled glyoxal vertical column densities. The impacts of several potential factors on glyoxal simulations over China have been investigated in January and July, including aromatic compound emissions (a, b, e, f, g, h), yields of glyoxal from isoprene (c, d, e, f, g, h) and yields of glyoxal from anthropogenic precursors (g, h). Display omitted
Air pollution has become a top environmental concern in China. In the present study, 9 years of PM sub(10) and PM sub(2.5) data from an urban monitoring station in Beijing was analyzed relative to ...other gaseous pollutants and several meteorological parameters. The levels and characteristics of particulate matters as well as the sources and factors affecting them were provided in the present study. During the 9-year observation period, PM sub(10) and PM sub(2.5) showed high levels, with annual mean values of 138.5 plus or minus 92.9 and 72.3 plus or minus 54.4 mu g/m super(3), respectively. Slight decreasing trends of annual mean PM sub(10) and PM sub(2.5) were observed; autumn was the main season that contributed to the decrease in annual mean PM sub(10) and PM sub(2.5). Higher values for both PM fractions were generally observed in the spring and summer months, respectively, whereas lower values were found in the summer and spring months, respectively. Pronounced diurnal variations were found for PM sub(10) and PM sub(2.5), which both displayed a bimodal pattern with peaks between 7:00 and 8:00 a.m. as well as 7:00 and 11:00 p.m.; a minimum generally appeared at approximately noon. The seasonal and diurnal variations in particulate concentration are mostly dominated by the seasonal and diurnal variability of boundary layer and source emissions. A principal components analysis revealed that both the traffic-related emissions and combustion sources were major contributions to the particles; their contributions ranged between 35.5-75.1 %. Furthermore, a directional analysis shows a stronger association between particles and the southerly winds, the PM derived from sources south of Beijing, most likely secondary PM, significantly affects concentrations at the sampling site. To improve air quality in Beijing, mitigation measures including phasing out high energy-consuming industries and prioritize the use of clean energy sources should be designed to reduce emissions from both local and regional sources.
The concentration, composition, and variability of nonmethane hydrocarbons (NMHCs) and carbon monoxide (CO) were characterized in a suburban region of south-central China. Weekly samples were ...collected in 2007 in the Changsha suburban area and analyzed with a three-stage preconcentration method coupled with GC–MS. A time series of NMHC measurements showed seasonal variation, with a higher level occurring in winter and a lower level in summer. Toluene was the most abundant species with an average concentration of 2.51
±
1.87 ppbv, followed by benzene (2.04
±
1.30 pptv). According to the level of identified NMHCs, vehicular exhaust appears to be the main source of NMHCs in Changsha. Among alkanes, the highest level is propane with a concentration of 1.31
±
0.71 ppbv, it indicated an extensive use and leakage of liquefied petroleum gas (LPG) in Changsha. The concentrations of NMHCs were influenced by the wind direction; a high level of NMHCs was carried by winds from southern China. Significant biogenic isoprene emissions were observed, with good correlation between isoprene level and temperature. Finally, when the typical individual NMHC species and CO in the morning and afternoon were compared, the shorter lifetime of NMHC species relative to CO could explain the poorer correlation observed in the afternoon.
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