Improved soil characteristics in the deeper plough layer can increase grain yield of winter wheat

In the North China Plain(NCP), soil deterioration threatens winter wheat(Triticum aestivum L.) production. Although rotary tillage or plowing tillage are two methods commonly used in this region, research characterizing the effects of mixed tillage on soil characteristics and wheat yield has been limited. A fixed-site field trial was carried out during 2011–2016 to examine the impacts of three tillage practices(5-year rotary tillage with maize straw removal(RT);5-year rotary tillage with maize straw return(RS);and annual RS and with a deep plowing interval of 2 years(RS/DS)) on soil characteristics and root distribution in the plough layer. Straw return significantly decreased soil bulk density, increased soil organic carbon(SOC) storage and SOC content, macro-aggregate proportion(R_(0.25)) and its stability in the plough layer. The RS/DS treatment significantly increased the SOC content, total nitrogen(TN), and root length density(RLD) in the 10–40 cm layer, and enhanced the proportion of RLD in the 20–30 and 30–40 cm layers. In the 20–30 and 30–40 cm layers, an increase in SOC and TN could lead to higher grain production than commensurate increases in the surface layer, resulting in a sustainable increase in grain yield from the RS/DS treatment. Thus, the RS/DS treatment could lead to high productivity of winter wheat by improving soil characteristics and root distribution at the deeper plough layer in the NCP.

THE CHARACTERISTICS OF 500 hPa GEOPOTENTIAL AND SST FIELD OF EXTREMELY SEVERE COLD MONTHS IN SOUTH CHINA WINTER

The region of south China is sometimes subject to major climatic catastrophes in winter. To have a clear understanding, the time in which extremely severe cold months occur in the south China wintertime over the past 45 years are determined and characteristics of the 500-hPa geopotential fields and SST fields are studied for the simultaneous and preceding 6-month periods. Similarity exists in the 500-hPa geopotential fields between each current severely cold month, with the geopotential pattern of being high in the north, but low in the south, of Asian-Pacific region and meridional circulation developing. The work presents anomalies of the months with significant differences in the 500-hPa geopotential field of the previous periods. The SSTA is continuous in the distribution from each extremely severe cold winter month back to the 6 months leading up to it for the region of south China while the SST pattern is of El Ni?o in January and the preceding 1 ~ 6 months for equatorial eastern Pacific but of La Ni?a in February and December. It is concluded that the prediction of severely cold winter months are possible with the use of the geopotential field at 500 hPa and the SST fields for the months ahead of the target time.

Variability and Variation Characteristics of Climate in Northern Winter Wheat Zone during 1961-2004

[Objective] The research aimed to study the variability and variation characteristics of climate in northern winter wheat zone during 1961-2004.[Method] Based on the meteorological data (temperature,precipitation and sunshine) of 55 meteorological stations in northern winter wheat zone during 1961-2004 and the yield data of winter wheat,by using the linear regression,correlated coefficient and climatic tendency rate,the spatial and temporal evolution characteristics of agricultural climatic resources (sunshine hours,temperature and precipitation) in northern winter wheat zone were analyzed.[Result] The annual average temperature,precipitation and sunshine hours in northern winter wheat zone during 1961-2004 all presented certain zonal distribution in the space.The precipitation and temperature gradually decreased from south to north.The sunshine hours gradually increased from south to north.The annual average temperature overall presented rise trend in northern winter wheat zone in 44 years,but the rise rate had difference in the different areas.The rise of annual average temperature in the high-latitude zone was more obvious than that in the low-latitude zone.The annual rainfall overall presented decrease trend,and the tendency rate of annual precipitation had significant difference in the different areas.The decrease rates of rainfalls in the central and western areas were bigger than that in other areas.The annual sunshine hours overall presented decline trend.In most areas,the tendency rate of annual sunshine hours was negative.But there was certain difference in the different areas.The zones where the decrease amplitude was smaller scattered in the west,and included central Shaanxi,south of Shanxi and some areas in southeast of Shandong.The decrease amplitudes were bigger in south of Henan,northwest of Shandong and south of Hebei.[Conclusion] The research provided theoretical basis for understanding the historical evolution of climate in northern winter wheat zone.

Analysis of the Winter Cloud-to-Ground Lightning Activity and Its Synoptic Background in China during 2010-20

Cloud-to-ground(CG)lightning data and the ECMWF ERA-Interim reanalysis dataset are analyzed to gain insight into the spatiotemporal distribution and synoptic background of winter-season CG flashes between December 2010 and February 2020 in China.We identify three Winter Lightning Frequent Areas(WLAs):the southwest side of the Yunnan-Guizhou Plateau(WLA1),the east side of the Yunnan-Guizhou Plateau(WLA2),and the Poyang Lake Plain(WLA3).The CG lightning flashes most frequently occur at local midnight and have a monthly peak in February.The CG lightning in WLA1 is mostly generated in non-frontal weather;however,the lightning in WLA2 and WLA3 mostly occurs in frontal systems.The frontal circulation situation is divided into four typical types:transversal trough after high pressure,low vortex,confrontational convergence,and asymptotic convergence.In all typical weather patterns,the lightning occurs downstream of a 500 hPa trough and is accompanied by a southwesterly low-level jet.The convective parameters of winter thunderstorms differ greatly from those of summer thunderstorms.The maximum convective available potential energy(MCAPE)and K-index(KI)are more useful metrics than convective available potential energy(CAPE)and Showalter index(SI)during winter.This study further deepens the understanding of the distribution characteristics of winter CG lightning in China,which motivates further research to improve the ability of winter thunderstorm prediction.

Transport Patterns and Potential Sources of Atmospheric Pollution during the ⅩⅩⅣ Olympic Winter Games Period

The attainment of suitable ambient air quality standards is a matter of great concern for successfully hosting the ⅩⅩⅣ Olympic Winter Games(OWG). Transport patterns and potential sources of pollutants in Zhangjiakou(ZJK) were investigated using pollutant monitoring datasets and a dispersion model. The PM_(2.5) concentration during February in ZJK has increased slightly(28%) from 2018 to 2021, mostly owing to the shift of main potential source regions of west-central Inner Mongolia and Mongolian areas(2015–18) to the North China Plain and northern Shanxi Province(NCPS) after 2018.Using CO as an indicator, the relative contributions of the different regions to the receptor site(ZJK) were evaluated based on the source-receptor-relationship method(SRR) and an emission inventory. We found that the relative contribution of pollutants from NCPS increased from 33% to 68% during 2019–21. Central Inner Mongolia(CIM) also has an important impact on ZJK under unfavorable weather conditions. This study demonstrated that the effect of pollution control measures in the NCPS and CIM should be strengthened to ensure that the air quality meets the standard during the ⅩⅩⅣ OWG.

VARIATION OF PRECIPITATION DURING WINTER AS A CAUSE OF SUSTAINED DROUGHT IN GUANGDONG DURING THE PAST 50 YEARS

The variation characteristics of precipitation during the winter(between October and the following March,to be referred to as just"the winter"hereafter) in Guangdong province during the past 50 years(from 1957 to 2006) and the relationship with Pacific SST are studied using the methods of Empirical Orthogonal Function(EOF) analysis,wavelet analysis,and correlation analysis.The results show that The Guangdong precipitation during the winter exhibits quasi-periodic significant oscillations of 40 years and 2 years;rainfall is less from the end of the 1950s to the start of the 1970s and from the end of the 1990s to the present than from the mid 1970s to the mid 1990s.The frequency of sustained drought is more than sustained flooding during the winter.The Guangdong precipitation during this time period is in significantly positive correlation to the equatorial central and eastern Pacific SST,but in a significantly negative correlation with the western and northern Pacific SST east of the Philippine Sea.61.5% of the sustained drought occurred in the phase of negative anomalies of the Nio3.4 index and 38.5% in the phase of positive ones.A composite analysis of atmospheric circulation is performed for the positive and negative phases of the Nio3.4 region associated with the sustained drought.The results showed that a weak polar vortex,a strong trough in Europe and a ridge near Balkhash Lake,active cold air and consistent northerly wind anomalies controlling Guangdong at low levels,an inactive westerly low disturbance in the low-mid latitude of the Asian continent,and a weak southern branch westerly trough,are all mutual causes for the sustained drought.

Distribution Characteristics of Winter Continuous Extreme Low Temperature in China

[Objective] The research aimed to study the distribution characteristics of winter continuous extreme low temperature in China. [Method] Based on the daily minimum temperature data in winter during 1961-2008 in 195 observatories, the continuous extreme low temperature event (cold night) which happened in winter in China and the distribution characteristics of accumulated temperature anomaly in 48 years were analyzed by using the actual probability distribution threshold method. [Result] Besides in Northeast China, Northwest China and Qinghai-Tibet Plateau where the geographical position was northerly, and the altitude was high, the long-time (above 5 d) extreme low temperature event was also easy to happen in the south of Yangtze River, especially in Guizhou, Guangxi, Hunan and so on. The continuous extreme low temperature event in the middle and lower reaches of Yellow River was the least. Started from the metaphase of the 1980s, the frequency trend of continuous extreme low temperature event decreased. But in 1992, 2000 and 2007, the low temperature event which continued above 7 d was more than the average. The accumulated cold in January in 48 years was the strongest. The second one was in February, and the smallest was in December. The accumulated cold in Northeast China and the north of Inner Mongolia was the biggest in December and January. The accumulated cold in the north of Xinjiang was the biggest in February. In the whole winter, the accumulated cold in Qinghai-Tibet Plateau was the smallest. The chilling injury was easier to happen in Guizhou, Guangxi and Hunan than other south areas in December and February. The occurrence probability of chilling injury in most areas of Szechwan Basin, Yunnan and Qinling Mountains in central China was smaller than that in other areas. [Conclusion] The research provided the reference basis for analyzing the influence of chilling injury on the agriculture in China.

Variation Characteristics of Winter Temperature in Jinan in Recent 60 Years

[Objective] The research aimed to study the variation characteristics of winter temperature in Jinan in recent 60 years.[Method] Based on winter monthly average,maximum and minimum temperatures in the ground observation station of Jinan during 1951-2010,by using linear trend,5-year moving average and anomaly,the variation characteristics of winter average,maximum and minimum temperatures in Jinan in recent 60 years were analyzed.The historical evolution trend and decadal variation characteristics were discussed.[Result] Winter average,maximum and minimum temperatures in Jinan in recent 60 years all presented slow fluctuation rise trend.The rise trend was obvious.Especially the increase amplitude of minimum temperature was the maximum.It illustrated that the variation of minimum temperature was more sensitive than that of maximum temperature,and the climatic warming in winter was mainly from the contribution of minimum temperature rise.Seen from the decadal variation,cold winter mainly appeared before the 1970s.Then,it presented obvious decrease trend.Conversely,warm winter presented increase trend after the 1970s.Warm winter phenomenon slowed after 2000.Winter temperature presented stepped warming trend during 1950s-1990s.Winter average temperature presented jumped warming trend when entered into the 1990s.The temperature presented downward trend when entered into the 21st century.But winter temperature still presented rise trend as a whole.The population growth in Jinan made that urbanization process accelerated,and urban heat island effect aggravated.It was one of important factors for climate warming in Jinan.[Conclusion] The research provided theoretical basis for understanding the long-term variation trend of climate in Jinan area,and if it was consistent with the background of global climatic warming.

A Synthetic Study of the Position Difference of the Southern Branch Trough of the Qinghai-Tibet Plateau Based on Objective Identification

The southern branch trough (SBT) mainly appears in the winter half year (November to May of the following year), using the 4 times daily NCEP/NCAR re-analysis data nearly 41 years (1979-2019) to analyze the differences of the SBT distribution of spatial location, frequency in winter and spring, then selects the “eastern type” and “western type” of the 10 most typical SBT, using simplified vertical vorticity tendency equation, using simplified vertical vorticity tendency equation to diagnosis of the SBT in power, heat, water vapor and wave energy in different positions. The results show that: 1) The location of the SBT is more eastward in winter, and more westward in spring. 2) The diagnosis results of the vorticity equation show that the vorticity of the southern branch of the “western type” is mainly contributed by advection term;the vorticity of the “eastern type” south branch is mainly contributed by the non-adiabatic heating term. 3) The SBT of the “eastern type” has more obvious vorticity advection than the southern branch of the “western type”, and the dynamic action is stronger. The “western type” SBT has stronger Q1, specific humidity advection and water vapor flux than the “eastern type” SBT, which is greatly affected by thermal action and water vapor. When the “eastern type” and “western type” SBT occur, the T-N wave activity flux appears obvious abnormal energy fluctuation propagation.

Spatio-Temporal Characteristics of Winter Cold Events in China from 1960 to 2020

Under the background of global warming, extreme cold events occur frequently. It is important to enhance the understanding of cold air patterns for forecasting cold air and reducing cold air-induced meteorological disasters. The study used the daily minimum temperatures from the National Climate Centre to classify the cold events affecting China into five different grades and the characteristics of different intensity cold events in China during the winter from 1960 to 2020 were analyzed. The results showed that there is little difference in the distribution of the frequency of general cold events from north to south, with duration longer in the north than in the south and an increase in frequency in the north in the last 60 years. The frequency of strong cold events is more in the north of China than in the south of China, and the duration is longer in the south than in the north China, with the frequency decreasing in most parts of the country. In addition to latitude, cold events frequency is closely linked to topography, with basins surrounded by high mountains being difficult to be affected by cold events, especially extreme cold events. In terms of month distribution, December was subject to the highest frequency of cold events and the longest duration of a single cold events process.

Effects of variation in food resources on foraging habitat use by wintering Hooded Cranes(Grus monacha)

Background:The ideal habitat use of waterbirds can be considered to be fixed,but current habitat use depends on environmental conditions,especially those of food characteristics,considered crucial to their use of habitats.Understanding how waterbirds respond to variation in food availability at degraded wetland sites and change their habitat use patterns over spatial and temporal scales should direct future conservation planning.The objectives of this study were to identify these spatial-temporal foraging habitat use patterns of Hooded Cranes(Grus monacha)and their relationship with food characteristics in the severely degraded wetlands of the Shengjin and Caizi lakes along with the Yangtze River floodplain.Methods:We investigated the changes in food characteristics,relative abundance and density of Hooded Cranes in various habitat types across three winter periods from November 2012 to April 2013.We examined the effect of these winter periods and habitat types on the pattern of use by the cranes and explored the relationship between these patterns and food characteristics using linear regression.Results:The food characteristics and habitat use clearly changed over spatial-temporal scales.In the early and mid-winter periods,the most abundant,accessible and frequented food resources were found in paddy fields,while in the late period the more abundant food were available in meadows,which then replaced the paddy fields.There were fewer effects of winter periods,habitat types and their interactions on habitat use patterns except for the effect of habitat types on the relative abundance,determined as a function of food abundance,but independent of food depth and sediment permeability.Conclusions:In response to the degradation and loss of lake wetlands,the cranes shifted their habitat use patterns by making tradeoffs between food abundance and accessibility over spatial-temporal scales that facilitated their survival in the mosaic of these lake wetlands.

Foliar K application delays leaf senescence of winter rapeseed(Brassica napus L.) under waterlogging

To better understand waterlogging effect on leaf senescence in winter rapseed (Brassica napus L.) during flowering stage, experiments were designed to explore foliar K application influences on adverse effects of waterlogging stress. Winter rapeseed was sprayed with K after waterlogging at initial flowering stage. Results indicated that waterlogging significantly decreased leaf net photosynthetic rate (Pn), stomatal conductance (Gs), intercellular CO2 concentration (Ci) and transpiration rate (Tr). It also declined maximum quantum yield of PS II (Fv/Fm), quantum yield of electron transport (ΦPS II) and photochemical quenching (qP), but increased leaf non-photochemical quenching (NPQ) and minimal fluorescence (Fo). Interestingly, exogenous application of K significantly alleviated waterlogging-induced photosynthesis inhibition. Foliar K application increased RuBisCO activation, chlorophyll and soluble protein contents, while significantly decreased MDA content under waterlogging stress. Moreover, K supplementation improved accumulation of K+, Ca2+, Mg2+, N, Zn2+, Mn2+, Fe2+ in leaves. In general, foliar K application is effective inalleviating deleterious effects of waterlogging stress and delays leaf senescence of winter rapeseed.

National Protection Zone for Rapeseed Production and Industrial Cluster of Rape in Hubei Province

Hubei Province is the main winter rapeseed producing area in China,and has the national advantage and characteristic industrial cluster of rape.The protection zone for the production of important agricultural products of rapeseed in Hubei Province also ranks first as that in Hunan Province.This paper studied the winter rape industry,the important agricultural product production protection zone of rapeseed,the provincial double-low high-quality rape protection zone and the industrial cluster of rape in Jianghan Plain in Hubei Province,and analyzed the main problems existing in the development of rapeseed production protection zone and industrial cluster of rape.Finally,it came up with strategies including promoting national rape varieties,overcoming the problem of rape"agricultural chip",promoting the"rice+rape"rotation model,and strengthening the protection of intellectual property rights of brand marks.

Production Performance of Different Varieties of Oat A vena sativa) in Winter Dry Land of Hunan

The phenological phase, plant height, filler number, nutritional composition, yield and stem/leaf ratio of three oat （Arena sativa） varieties （lines） in winter dry land of Hunan were studied. The result shows that the three oat varieties were greatly different in plant height, nutritional composition, yield and stem/leaf ratio. Baiyan 7 had the best performance, with the plant height, tiller number and fresh yield of 101.67cm, 7.6 tiller/plant and 70.15 t/hm2 respectively ; the crude protein content of dry matter of Baiyan 7 was 32.63% ; the leaf weight per tiller of Baiyan 7 accounted for 31.6% of single tiller weight, while those of Baiyan 8 and Baiyan 2 accounted for 31.3% and 29.2%, respectively. The single tiller weight of oat could be estimated/calculated by the model/formula Y = 0.043 7X - 2.89 （ R2 = 0.913 4, P 〈 0.01 ）, where Y is the single tiller weight （ g ） and X is the plant height （cm）. Comprehensive analysis showed that Baiyan 7 had higher yields and stem/leaf ratio. Thus, Baiyan 7 is more suitable for planting as a winter-spring forage in the winter dry land of Hunan.

不同带宽与行距配置对垄作冬小麦农艺性状、品质及水分利用的影响

为筛选出适宜强筋冬小麦高效的垄作栽培模式,在大田试验条件下,研究常规条播(TCK)、垄作2条带宽幅播种(T2)、垄作常规条播的3条带(T3)及垄作常规条播4条带(T4)不同结构配置处理方式对冬小麦群体分蘖、茎秆特性、光合特性、品质和水分利用效率等方面的影响。结果表明:在冬小麦整个生育时期T4处理下的分蘖数量显著低于其他处理,成熟期时T2处理的冬小麦群体数量显著高于其他处理。4种处理下的叶面积指数随着生育进程的推进呈先升高后降低的单峰曲线波动,在孕穗期出现峰值。在花后7,14,21d,以及TCK处理下的光合作用参数显著低于T2、T3处理,但显著高于T4处理。垄作栽培有助于降低冬小麦株高、重心高度、节间长度,均显著低于TCK处理。随着垄台上冬小麦行距的减少,冬小麦的株高、重心高度、节间长度逐渐升高,三者均表现为T2<T3<T4。T2与TCK、T3、T4处理相比较,其籽粒产量分别提高3.0%、1.5%和14.0%,水分利用效率分别提4.2%、0.6%和10.1%。综上所述,T2是有利于强筋小麦稳产保质节水抗倒的较优栽培方式。

寒地城市老幼群体不同季节住区户外活动特征及其影响因素研究

住区是承载老幼群体户外活动的主要场所,寒地城市特殊气候条件下的季节变化对老幼群体的活动特征影响显著,本文根据其影响因素提出满足老幼群体全季节活动需求的共享型户外活动空间营造策略。利用实地调研与问卷结合的方式对哈尔滨市6个样本住区452组老幼群体进行调查,研究不同季节老幼群体住区户外活动的时间与空间分布特征,并通过多元回归分析的方法分别提取不同季节下老幼群体活动频率、活动时长和活动类型的影响因素。基于研究结果,从优化目标、优化机制、环境营造三方面提出寒地住区户外活动空间的优化策略。

江苏省冬小麦需水量时空变化特征及气候影响因素分析

为实现江苏省冬小麦科学灌溉、提高农业用水效率,明晰江苏省冬小麦需水量及气候影响因素的时空变化特征,为全省冬小麦灌溉管理及农业水资源高效利用提供科技支撑,基于江苏省共计12个地区2013-2022年冬小麦季相关气象资料,通过Penman-Montieth法计算近十年来江苏省冬小麦需水量,并利用Pearson相关分析法对近十年江苏省冬小麦需水量时空变化特征、需水特性以及气象影响因素进行了分析。近十年间江苏省年平均气温、日平均湿度、地表温度、降水量、蒸发量、平均日照时数均呈总体上升趋势,太阳总辐射量呈减小趋势。近十年来江苏省冬小麦本田期的需水量平均值为451.82~692.50 mm,年际变化范围在540.19~646.70 mm,不同年份间呈现减小的趋势,空间上则呈现由西北向东南递减的趋势。江苏省大部分地区冬小麦需水强度最小值出现在1月,5-6月抽穗期与灌浆期需水强度最大。江苏省冬小麦全生育期需水量与年均降雨量、日均湿度之间存在负相关关系,与年均水面蒸发量、年均日照时数、年平均气温间存在正相关关系,这其中以日均湿度、年均水面蒸发量、年均气温对冬小麦需水量的影响最为明显。并且,近十年冬小麦全生育期需水量的总体下降趋势可能是由于其与日均湿度明显更高的负相关性所导致。总之,近十年来江苏省冬小麦需水量逐年有下降趋势,且由西北向东南递减,此外全省日均湿度、年均水面蒸发量、年均气温是近年来冬小麦需水量变化的主要影响因素。

不同秸秆还田技术模式对冬小麦强弱势粒灌浆特性的影响

为揭示砂姜黑土区不同秸秆还田技术模式对冬小麦籽粒灌浆进程的影响,该研究基于农业农村部华东地区作物栽培科学观测站15a的长期定位试验,设置单季小麦秸秆全量粉碎覆盖还田(T1)、小麦秸秆全量粉碎覆盖还田+玉米秸秆全量粉碎翻埋还田(T2)、单季玉米秸秆全量粉碎翻埋还田(T3)和小麦玉米秸秆全年不还田(CK)4种不同秸秆还田技术模式,采用Richards方程模拟冬小麦籽粒灌浆过程,研究不同秸秆还田技术模式对冬小麦强弱势粒灌浆特征参数的调控效应。结果表明:1)相较于秸秆不还田,秸秆还田处理能提升冬小麦强、弱势粒的籽粒体积、千粒质量和产量,T1、T2、T3处理下强势粒千粒质量和籽粒产量较CK分别显著提升11.02%、10.63%、13.75%和16.28%、14.29%、13.94%,弱势粒千粒质量和籽粒产量较CK分别显著提升9.73%、6.64%、7.57%和19.24%、23.25%、11.50%。Richards方程能极显著模拟不同秸秆还田技术模式下冬小麦籽粒灌浆过程,拟合方程决定系数(R^(2))均在0.997以上。2)对冬小麦强势粒,秸秆还田可延长小麦强势粒灌浆时间,主要通过缩短灌浆渐增期持续时间和提高其灌浆速率,延长灌浆缓增期的持续时间来提升强势粒千粒质量。其中T1、T3处理下冬小麦强势粒灌浆持续时间较CK分别延长2.137 d和4.443 d,T1、T2处理下强势粒单粒最大灌浆速率较CK分别显著提高了7.81%和12.26%。3)对冬小麦弱势粒,T1处理下弱势粒灌浆持续时间较CK延长1.477 d,T1、T2、T3弱势粒单粒最大灌浆速率较CK分别显著提升16.46%、22.69%和17.13%。该研究表明秸秆全量还田可提升砂姜黑土区冬小麦籽粒库容和籽粒灌浆速率,最终增加粒质量。研究可为砂姜黑土区秸秆资源的高效利用提供理论指导和技术支撑。

《复》卦与冬至节气:天地人融通的文化蕴涵

在古代天文历法发展史上,冬至是最早被测定的时间节点之一,具有重要的标志性意义。《周易》的《复》卦,从象数模式到义理蕴涵,都与冬至节点形成了密切的联系。历代学者都对此展开阐释发挥,其中具有天地人融通的丰富文化蕴涵,包括“七日来复”所含藏的天道运行规律,“复其见天地之心乎”所引申出的人性、修养论的哲思,“先王以至日闭关”延伸出的制度文化。通过《复》卦与冬至节气关联性的论析,可以认识到易学与天文学存在密切关系,并已积淀为极具特色的文化传统,具有独特的文化价值和深刻的启发意义。

Pollution levels, composition characteristics and sources of atmospheric PM2.5 in a rural area of the North China Plain during winter

The pollution levels,composition characteristics and sources of atmospheric PM2.5 were investigated based on field measurement at a rural site in the North China Plain(NCP) from pre-heating period to heating period in winter of 2017.The hourly average concentrations of PM2.5 frequently exceeded 150 μg/m3 and even achieved 400 μg/m3,indicating that the PM2.5pollution was still very serious despite the implementation of stricter control measures in the rural area.Compared with the pre-heating period,the mean concentrations of organic carbon(OG),element carbon(EC) and chlorine ion(Cl-) during the heating period increased by 20.8%,36.6% and 38.8%,accompanying with increments of their proportions in PM2.5from 37.5%,9.8% and 5.5% to 42.9%,12.7% and 7.2%,respectively.The significant increase of both their concentrations and proportions during the heating period was mainly ascribed to the residential coal combustion.The proportions of sulfate,nitrate and ammonium respectively increased from 9.9%,10.9% and 9.0% in nighttime to 13.8%,16.2% and 11.1% in daytime,implying that the daytime photochemical reactions made remarkable contributions to the secondary inorganic aerosols.The simulation results from WRF-Chem revealed that the emission of residential coal combustion in the rural area was underestimated by the current emission inventory.Six sources identified by positive matrix factorization(PMF) based on the measurement were residential coal combustion,secondary formation of inorganic aerosols,biomass burning,vehicle emission and raising dust,contributing to atmospheric PM2.5 of 40.5%,21.2%,16.4%,10.8%,8.6% and 2.5%,respectively.