Comprehensive analysis of the impact of climatic changes on Chinese terrestrial net primary productivity

Recent climatic changes have affected terrestrial net primary productivity (NPP). This paper presents an investigation of the impact of climatic changes on Chinese terrestrial vegetation NPP by analyzing 18 years’ (1982 to 1999) climatic data and satellite observations of vegetation activity. Results indicate that climatic changes in China have eased some critical climatic constraint on plant growth. (1) From 1982 to 1999, modeled NPP increased by 1.42%·a-1 in water-limited regions of Northwest China, 1.46%·a-1 in temperature-limited regions of Northeast China and Tibet Plateau, and 0.99%·a-1 in radia- tion-limited regions of South China and East China. (2) NPP increased by 24.2%, i.e. 0.76 petagram of carbon (Pg C) over 18 years in China. Changes in climate (with constant vegetation) directly contrib- uted nearly 11.5% (0.36 Pg C). Changes in vegetation (with constant climate) contributed 12.4% (0.40 Pg C), possibly as a result of climate-vegetation feedbacks, changes in land use, and growth stimula- tion from other mechanisms. (3) Globally, NPP declined during all three major El Ni-o events (1982 to 1983, 1987 to 1988, and 1997 to 1998) between 1982 and 2000, but Chinese vegetation productivity re- sponded differently to them because of the monsoon dynamics. In the first three events (1982 to 1983, 1987 to 1988, and 1992), Chinese vegetation NPP declined, while in the later two events (1993, 1997 to 1998) increasing obviously.     

1982—1999年我国植被净第一性生产力及其时空变化

基于地理信息系统和卫星遥感技术,利用植被、气候和土壤等地面空间数据,应用CASA模型估算了1982—1999（除1994）年间我国植被年净第一性生产量及其时空变化。结果表明：18年间我国植被净第一性生产量呈增加趋势,平均增加速率为0.024PgC·a^-1,其均值为1.8PgC,其中高寒植被、常绿阔叶林和常绿针叶林的增加速度最快;降水是限制我国植被净第一性生产力的主要因子。     

Palaeoenvironmental changes from pollen record in deep sea core PC-1 from northern Okinawa Trough, East China Sea during the past 24 ka

A pollen record of core PC-1 from the northern Okinawa Trough, East China Sea （ECS）, provides information on vegetation and climate changes since 24 cal. kaBP. A total of 103 samples were palynologically analyzed at 8 cm intervals with a time resolution of 230 a. Four pollen zones are recognized： zone Ⅰ （812-715 cm, 24.2-21.1 cah kaBP）, zone Ⅱ （715-451 cm, 21.1-15.2 cah kaBP）, zone Ⅲ （451-251 cm, 15.2-0.8 cah kaBP）, zone Ⅳ （251-0 cm, 10.8-0.3 cal. kaBP）, corresponding to Late MIS 3, Last Glacial Maximum （LGM）, deglaciation and Holocene, respectively. The LGM is characterized by the dominance of herbs, mainly Artemisia, and high pollen influx, implying an open vegetation on the ex- posed continental shelf and a cool and dry climate. The deglaciation is a climate warming stage with Pinus percentage increased and Artemisia percentage decreased and a rapid sea-level rise. The Holocene is characterized by predominance of tree pollen with rapid increase in Castanea-Castanopsis indicating the development of mixed evergreen and deciduous broad-leaved forest and a warm, humid climate. Low pollen influx during the Holocene probably implies submergence of the continental shelf and retreat of the pollen source area. The vegetation indicated by pollen assemblage found in this upper zone is consistent with the present vegetation found in Kyushu, Japan. Originating from the humid mountain area of North Luzon of the Philippines, Tasmania and New Zealand, Phyllocladus with sporadic occurrence throughout PC-1 core probably suggests the influence of Palaeo-Kuroshio Current or intense summer monsoon. The observed changes in Pinus and Herbs percentage indicate fluctuations of the sea level, and high Pinus percentage corresponds to high sea level. Spectrum analysis of the pollen percentage record reveals many millennial-scale periodicities, such as periodicities of 6.8, 3.8, 2.2, 1.6 ka.     

Discovery of a large area of ice-wedge networks in Ordos： Implications for the southern boundary of permafrost in the north of China as well as for the environment in the latest 20 kaBP

Deep sea deposits, ice cores and loess deposits have been used extensively and successfully, to study global climatic changes. Since permafrost is a consequence of cold climates, indicators of permafrost can also be used to reconstruct ancient climates in certain areas during certain periods. The recent discovery of large areas of ice wedge networks, and determination of their ages, have enabled us to locate the southern boundary of the permafrost that ex-isted in China about 20 thousand years…     

用直接接触式膜蒸馏浓缩中药提取液

对直接接触式膜蒸馏浓缩中药提取液进行了研究,分析了浓缩过程跨膜通量下降的原因,并考察了药液温度和流速对跨膜通量的影响。结果表明:由提取液中固体颗粒等污染物造成的膜污染以及膜表面处水蒸汽压下降是浓缩过程跨膜通量下降的主要原因。在浓缩倍数较低(1.0～4.0)的范围内,通量下降主要是由膜污染造成的;在浓缩倍数较高（4.0～16.0）的范围内,膜表面处水蒸汽下降也显示其影响。药液温度从46℃升高到60℃,通量从13.88kg/(m²·h)升高到30.82kg/(m²·h)。药液流速从0.074m/s升高到0.130m/s,通量从24.14kg/(m²·h)升高到31.22kg/(m²·h)。     

Characterization of MASDs of surface soils in north China and its influence on estimating dust emission

Inordertoquantitivelyevaluateeffectsofdustaerosolonradiativeforcing[1],andtounderstandtheprocessofatmosphericchemistryandbiogeochemistry[2,3],modelingthedustemissionfluxisakindoffundamentalwork.TheDPMmodel[4—6]isidealforpredictingdustemission[7—10]becauseitconsiderseffectsofsurfacefea-tures(MASDofsurfacesoil,roughnesslengthandsoilmoisture,etc)andsandblastingprocess.Italsoprovidesanexplicitphysicalmechanismthatisvalidatedbywindtunnelandfieldexperiments[7—10].Themeandiameterofsurfacesoilsi…     

基于CASA模型的广西植被NPP季节变化研究

植被净初级生产力（Net Primary Productivity，NPP）是判定陆地生态系统碳汇/源的关键要素，不仅直接代表了自然环境条件下植被群落的生产能力，还体现了陆地生态系统的质量水平。本文基于陆地生态系统碳汇模型（CASA模型），利用2019年中分辨率成像光谱仪（MODIS）归一化植被指数（NDVI）数据和其他气象数据，对月、季节、年尺度上的广西植被NPP的空间变化进行估算，分析其时空变化特征，并探讨不同植被类型、气象因子和地形地貌对其的影响。结果表明：2019年广西整体区域的植被NPP平均值为880.56 g C·m^-2·a^-1，植被NPP空间分布呈内陆中心向四周递增、东北部向西南部递增的特点。月植被NPP在时间序列上总体呈现正弦曲线的变化特征，1-8月的植被NPP呈上升趋势，在8月达到峰值，而且9月仍然维持较高值；之后至12月，植被NPP逐步下降。广西植被NPP的季节变化明显，冬季的植被NPP整体最低，区域差异性不突出；夏季的植被NPP整体最高，区域差异性突出。常绿阔叶和混交林分布面积广且其光能利用率较大，对广西植被NPP贡献较大。从月尺度上来看，月植被NPP与月累计降水量主要呈负相关关系，与月平均气温主要呈正相关关系；月平均气温与月植被NPP的偏相关性比月累计降水显著，月平均气温是广西月植被NPP的主要影响因子。在中海拔地区（700-1 300 m），植被NPP并不受喀斯特地质环境背景的影响，喀斯特地区和非喀斯特地区植被NPP相差不大且随着海拔高度的上升趋于稳定。在全球变化背景下，分析广西植被NPP的时空演变规律及其与环境要素之间的关系，可为广西生态环境监测与管理、生物多样性保护、生态服务评估等提供科学参考。     

Simulation study of China’s net primary production

Spatial and temporal distribution of vegetation net primary production （NPP） in China was studied using three light-use efficiency models （CASA, GLOPEM and GEOLUE） and two mechanistic ecological process models （CEVSA, GEOPRO）. Based on spatial and temporal analysis （e.g. monthly, seasonally and annually） of simulated results from ecological process mechanism models of CASA, GLOPEM and CEVSA, the following conclusions could be made： （1） during the last 20 years, NPP change in China followed closely the seasonal change of climate affected by monsoon with an overall trend of increasing; （2） simulated average seasonal NPP was： 0.571±0.2 GtC in spring, 1.573±0.4 GtC in summer, 0.6±0.2 GtC in autumn, and 0.12±0.1 GtC in winter. Average annual NPP in China was 2.864±1 GtC. All the five models were able to simulate seasonal and spatial features of biomass for different ecological types in China. This paper provides a baseline for China＇s total biomass production. It also offers a means of estimating the NPP change due to afforestation, reforestation, conservation and other human activities and could aid people in using for-mentioned carbon sinks to fulfill China＇s commitment of reducing greenhouse gases.     

Vegetation evolution and millennial-scale climatic fluctuations since Last Glacial Maximum in pollen record from northern South China Sea

A large number of paleoclimate records reveal subMilankovitch climatic fluctuations on the millennial-scalesuperimposing on the Earth orbital cycles[1], such as theHeinrich ice draft events in the Atlantic (each intervalabout 7000–10000 a)[2,3], the Dansgaard/Oeschger (D-O)events (millennial-scale) in Greenland Ice Cores and theBond cycle composed of a Heinrcih event after severalD-O events[4]. At present, most recent work on millennial-scale climatic fluctuations focuses on the high lat…     

临汾盆地陶寺遗址附近全新世黄土剖面的环境指标分析

在对临汾盆地陶寺遗址北城墙外全新世黄土剖面粒度、磁化率、Rb/Sr值和CaCO₃含量等气候指标进行分析的基础上, 结合光释光测年结果和考古学资料, 探讨该剖面记录的环境信息及其与文化发展的相互关系。研究发现: 全新世早期(10.5~9.6 kaBP), 东亚冬季风较弱, 风化成壤作用增强, 气候由凉干转向暖湿; 全新世早中期(9.6~4.9 kaBP), 风化成壤作用最强, 气候最为暖湿; 全新世中后期(4.9~2.5 kaBP), 风化成壤作用较之前有所下降, 气候较之前温干, 但较现今暖湿; 全新世晚期(2.5 kaBP)以来, 东亚冬季风增强, 风化成壤作用较弱, 气候较为凉干。暖湿气候期与文化的繁荣发展时期有较好的对应关系, 凉干气候期植被的退化可能受气候和人类活动共同作用的影响。     

Inverse correlation between ancient winter and summer monsoons in East Asia？

There is a scientific debate on the relationship between ancient winter and summer monsoons in East Asia. Some scholars think that East Asian winter and summer monsoons are anti-correlated, and others think not. For this reason, this study is motivated to assess their linkage from the paleoclimate simulation perspective, through analyzing the Last Glacial Maximum （LGM） and mid-Holocene （MH） climate simulated by CCSM3 model. Compared to the present climate, the Aleutian low is found to be deepened and the East Asian winter monsoon （EAWM） is stronger during the LGM winter. The Pacific high in summer is noticed to be weakened and the East Asian summer monsoon （EASM） is weaker at the LGM. During the MH, the Aleutian low and the Asian high in winter are intensified, and the Asian low and the Pacific high in summer are enhanced, indicating that the EAWM and EASM are both stronger than today. Therefore, the EAWM is not always negatively correlated to the EASM. Their relationship may be different at different geological stages. It can be obtained at least from the numerical simulation results that the EAWM and the EASM is negatively correlated during the cooling period, while positively correlated during the warming period.     

长白山阔叶红松林净初级生产力对气候变化的响应: 基于BIOME-BGC模型的分析

为了分析气候变化和大气CO₂浓度增加对长白山阔叶红松林净初级生产力(NPP)的影响, 运用本地参数化后的BIOME-BGC模型进行模拟, 并以实测NPP和增强型植被指数(EVI)进行验证。模拟结果表明, 长白山阔叶红松林NPP均值为611.71 gC/(m²•a), 1960-2011年年际间的波动范围是473.28~703.44 gC/(m²•a)。模拟结果与基于样地实测的NPP (均值为594.66 gC/(m²•a))相似; 同时, BIOME-BGC模型模拟的NPP年际间变化趋势与EVI的波动趋势相似, 二者间存在显著的相关关系, 表明模型能较好地模拟生产力的时间动态。模拟表明, 红松的NPP与降水关系更为密切, 而阔叶树NPP与温度、降水都呈显著的正相关。模型预测, 在未来CO₂浓度加倍和温度、降水同时增加的场景下, 长白山阔叶红松林NPP将显著增加, 其中阔叶树和红松的NPP将分别增加27.87%和23.96%。单独增加温度(2℃)或单独增加降水(12%)都能促进阔叶树和红松NPP的增加, 其中降水的作用弱于温度的作用, 而单独CO₂浓度的倍增对阔叶树和红松的NPP没有明显的影响。     

陆地生态系统生产力模型研究进展

目的 通过净初级生产力(NPP)模型研究回顾,为全球陆地碳循环和全球变化等研究提供方法参考.方法 把生产力模型大致归为3类,分别阐述其研究进展.结果 气候相关模型通过对气候因子与植物干物质生产的相关性分析来估算植被的净初级生产力;生物地球化学循环模型以气候、土壤条件和植被类型为输入变量,主要模拟破、水和营养物质的循环;基于遥感资料的模型基于植被指数与冠层吸收的光合有效辐射部分之间的关系得到吸收光合有效辐射,进而建立大尺度的卫星观测与生物生产力的关系.结论 无论应用哪种生产力模型,都受到较多条件的限制,因此,目前应用模型计算净初级生产力仍存在一些不足之处.     

戊二醛交联PVA/PAN复合膜渗透汽化性能的实验研究

研究了戊二醛交联时间对PVA/PAN复合膜分离性能的影响,并用于乙醇水溶液的分离。结果表明,交联处理存在着最优时间。对应于最优交联时间的膜,当料液中乙醇质量分数(wE)为96.2%,料液温度(t)为70℃时,渗透通量(J_t)为337(g·m^-2·h^-1),分离因数(α_W/E)为389.7。进一步考察了料液质量分数为30%～98.3%,料液温度为50～78℃时,交联膜的分离性能。     

Methane emissions from terrestrial plants over China and their effects on methane concentrations in lower troposphere

Methane (CH₄) is the most important greenhouse gas and reactive trace gas in the atmosphere. Recently, it has been reported that terrestrial plants can emit CH₄ under aerobic conditions, which may call for reevaluation of the inventory of CH₄ emissions in China. In this paper, those emissions over China and their effects on CH₄ concentrations in lower troposphere were investigated. Firstly, based on the work of Keppler et al., the aerobic plant CH₄ emission model (PLANTCH4) for China was established. And by using the database of normalized difference vegetation index (NDVI) derived from NOAA/AVHRR, the distribution of net primary productivity (NPP) over China was simulated, and thereby, for the first time, the amount and distribution of the newly identified source in China were estimated. Secondly, with the aid of the three-dimensional atmospheric chemistry model system (MM5-CALGRID), the effects of the emissions were studied. The results show that the annual aerobic plant CH4 emissions over China amount to 11.83 Tg, i.e. nearly 24% of Chinese total CH₄ emissions. And the major fraction (about 43%) comes from forests. When those emissions are considered in modeling, computed countrywide mean surface concentration of CH₄ is 29.9% higher than without them, with a maximum increase of 69.61 μg·m⁻³ in the south of Yunnan Province. In conclusion, to study CH₄ emissions from terrestrial plants over China may have important implications for correctly estimating the contribution of China to global CH₄ budget, and may call for a reconsideration of the role of CH₄ in global and regional environment and climate change. Supported by National High-Tech Research & Development Program of China (Grant No. 2006AA06A307), National Basic Research Program of China (Grant Nos. 2006CB403706 and 2006CB403703), and the Program for New Century Excellent Talents in University, and Nanjing University Talent Development Foundation     

Sm(Ⅲ)-HP配合物与DNA的作用机制

 应用紫外-可见光谱法和荧光光谱法并以中性红(NR)作光谱探针研究了Sm(Ⅲ)HP配合物与DNA的作用机制。研究表明,血卟啉(HP)与Sm(Ⅲ)的配合比n_Sm(Ⅲ)∶n_HP = 1∶ 1,Sm(Ⅲ)HP配合物与DNA的结合比n_Sm(Ⅲ)HP ∶ n_DNA = 1∶ 1,Sm(Ⅲ)HP配合物与DNA的结合常数K^θ_30℃ = 1.67×10⁴  L/mol。该过程为熵所驱动,其Δ _r H_m为4.86×10⁴ J/mol,Δ_r S_m为195.61 J/(mol·K),30 ℃时Δ_r G_m为－1.06×10⁴ J/mol。Scatchard法和探针法研究表明,Sm(Ⅲ)HP与DNA之间的结合方式主要是沟区作用。     

Preliminary study on LGM climate simulation and the diagnosis for East Asia

LGM climate study is a hot topic in international fields on global changes. Climate simulation in this study applies both common designs of 21 kaBP boundary conditions from the Paleoclimate Modeling Intercomparison Project (PMIP), including insolation, glaciation, sea surface temperature and atmospheric CO₂ concentration, and land surface conditions from Eurasia continent by compilation of geological evidence. The simulation outputs are in agreement with climate spatial patterns reconstructed by observation records. Sensitive experiment on land surface conditions shows that changes in vegetation would make significant impacts on temperature and precipitation. Particularly in the Tibetan Plateau, this change would increase in differences of winter and summer temperature, precipitation and P-E.     

Imprint of solar activity on Nanjing stalagmite annual layer thickness sequence during the Last Glacial Maximum

PREVIOUS STUDIES ON ANNUAL GROWTH LAMINAE IN STA-LAGMITES SUGGESTED THAT IT IS A USEFUL PROXY TO INVESTI-GATE ANNUALLY HIGH-RESOLUTION CLIMATES[1―4].THE VARIA-TION OF ANNUAL LAMINAE THICKNESS HAS BEEN EXPLAINED AS REFLECTING SEASONAL CHANGES EITHER IN DR…     

Evidence of a humid mid-Holocene in the western part of Chinese Loess Plateau

Field works show that the wetland/swamp layers were distributed ubiquitously in the western part of the Chinese Loess Plateau. Universality of the wetland/swampy layer and the consistency of the age reveal that the layer was developed under the humid climatic condition. Dated between 9 and 3.8 kaBP, the wetland/swampy layer is full of aquatic mollusks and has the highest tree and shrub pollen,indicating a humid mid-Holocene. Variations of grain size suggest that winter monsoon weakened during 9-3.8 kaBP while climate change to humid and vegetation cover increased from 9 kaBP onward. After 5.9 kaBP, the humidity declined gradually. In 3.8 kaBP, summer monsoon sharply retreated, and the climate changed to dry.     

Preliminary reconstruction of spatial precipitation patterns and atmospheric circulations in China during the late Quaternary

Quantitative estimates of the precipitation on different lake sites at the three time phases, i.e. 30, 18, and 6 kaBP by using the combined hydrological and energy budget model, make it possible to reconstruct the large changes in spatial precipitation patterns since the late Quaternary. The results have shown that, very strong precipitation occurred in western China at 30 kaBP, suggesting extremely enhanced summer Indian monsoon. Precipitation was high in southwestern China at 18 kaBP, especially the southern part of southwestern China, due to the southward shift of the westerlies and a low pressure cell occurred over northern India. The precipitation at 6 kaBP shows the complicated patterns for different regions of China, suggesting different climate dynamics. The comparison of the independent lake level/ area-based reconstruction of precipitation and the palaeo-climate simulations is an effective way for the validation ofeach method to reconstruct the palaeo-precipitation quantitatively, and for understanding the dynamic mechanisms of climatic change.