Crustal evolution in the silicate planets

This paper reviews recent discoveries from space missions to the Moon, Mercury, Mars, and Venus, and their implications for planetary development. It appears that all these planets have undergone similar sequences of crustal evolution, the chief difference among them being how far each has evolved. All have apparently undergone a first differentiation in which a global crust was formed. This crust was partly disrupted by heavy impact bombardment some 4·10⁹ years ago. A second differentiation, resulting in basalt eruptions, followed. The Moon and Mercury essentially stopped evolving at this point; Mars and Venus continued to a stage of incipient plate tectonics, with crustal fracturing and vulcanism. Terrestrial Precambrian geologic evidence is consistent with a similar but further-advanced evolutionary sequence for the Earth as well, and the theory is proposed that terrestrial continents are the greatly altered and redifferentiated remnants of an originally global igneous crust of intermediate composition. The ocean basins of today are the multi-cyle descendants of mare-like basins localized by a late heavy bombardment about 4·10⁹ years ago analogous to that which formed the lunar mare basins and similar basins on other planets.     

黄海硅的分布与收支研究

基于2012年在黄海的综合调查,对黄海水体和沉积物中溶解硅和生物硅的含量和分布及主要影响因素进行了分析,并结合历史数据建立了黄海硅收支与循环的模型.结果表明,黄海水体溶解硅和生物硅在秋季均高于春季,生物硅占活性硅的22%,陆源输入、初级生产和底界面扩散对硅的含量和分布的影响较为突出.收支表明,底界面扩散是黄海水体溶解硅的主要来源,占外部输入的48%,其次是东海的输入,占32%,河流贡献为9%,地下水贡献为6%,地表径流(非河流部分)贡献为3%,渤海贡献为1.5%,大气仅贡献0.5%;黄海水体溶解硅的支出主要是通过生物的吸收与随后的沉积埋藏和向东海的输出,其比例分别为72%和27%,黄海向渤海输出比例仅为1.0%;黄海沉积物是水体溶解硅的源,同时黄海体系还具有潜在汇的特性;黄海硅的净埋藏量约为55×109mol/a,占当年生物硅总量的7.2%,高于全球海洋的平均比值(3%),是外部输入硅总量的47%.本研究量化了黄海硅循环的主要过程,初步揭示了硅的源-汇特征以及陆地输入对近海硅收支与循环的影响.     

大气硫循环中的自然硫释放研究

基于当前可获得的与该课题相关资料 ,综述了陆地生态系统对全球硫总量的贡献。第 1部分阐述了已熟知的自然硫源——海洋硫循环的了解。第 2部分给出了陆地硫循环的基本情况及各化学组分和源的相对重要性。第 3部分给出以前报导的各硫源的几种主要含硫气体的通量值 ,通过比较推导出对应各环境的代表性硫通量值。最后的第 4部分作为总结讨论了克服早先自然生态系统硫循环研究测定中的各种局限的方向并提出建议。     

Die Kleinen Planeten

The orbits of 1900 minor planets have been accurately established. The results of a statistical survey of the numerous faint asteroids are available. Special types of orbital motion are revealed in a comparison of the range of variation of heliocentric distance for minor and major planets. New methods are provided for determining asteroid diameters. The resulting low mean density of Ceres is comparable to the densities of some types of carbonaceous chondrites. Measurements of reflectivity as a function of wavelength allow another comparison of asteroids and meteorites. The evolutionary process that led to the present population of minor planets is probably different for objects on regular and unusual orbits.     

自然生态系统中厌氧氨氧化和反硝化耦合反应研究进展

厌氧氨氧化和反硝化反应是氮循环系统的两个关键环节,它们对平衡整个生态系统氮的收支、改善水体氮的污染、减少温室气体的排放均具有重要意义.在阐述厌氧氨氧化和反硝化生物反应及微生物学机理的基础上,着重综述了二者在水生和陆地两个生态系统中的耦合反应:①探讨了厌氧氨氧化和反硝化反应在不同环境背景下发生的介质及N₂的产生速率和贡献比率,发现水生生态系统中厌氧氨氧化对N₂产生的贡献率相对陆地生态系统占有较大比重.②分析了调控厌氧氨氧化和反硝化反应的细菌群落和功能基因,反应系统占主导的微生物种类随环境发生变化,其中厌氧氨氧化菌Candidatus brocadia作为主导细菌出现频率较高.③二者耦合过程中的影响因素包括环境因素与底物因素.其中,环境因素中厌氧氨氧化与反硝化耦合的最适pH为6.7~8.3,且溶解氧含量过高时也会对耦合反应产生抑制作用;在底物环境中,有机物含量或C/N过高会促进反硝化作用,但同时也会抑制厌氧氨氧化的发生.建议以后能够加大对于厌氧氨氧化和反硝化耦合反应全球尺度的研究,特别是对于陆地生态系统,还应加深对厌氧氨氧化反应速率与反硝化反应速率之间关系的理论与应用研究;同时,在实际应用中,需要在确定厌氧氨氧化菌和反硝化菌最佳生长基础上,建立耦合体系理论预测数学模型,量化两类功能性微生物的耦合效果.      

巴丹吉林沙漠腹地夏季不同天气条件下陆-湖面辐射收支与能量分配特征对比

论文以巴丹吉林沙漠腹地陆面和湖面能量平衡系统的定位观测数据为基础,对比分析了夏季不同天气条件下两种典型下垫面的辐射收支和能量分配之异同,评价了典型晴天的辐射收支与能量分配对季节平均气候态的代表性。结果显示,按“晴天-多云-阴天-降水”的顺序,陆面与湖面的总辐射、反射短波辐射和净辐射之日均值呈逐渐减小趋势,大气逆辐射则逐渐增大。湖面长波辐射亦随这一天气变化顺序逐渐增大,暗示地下水携带的热量和局地平流作用对湖水表面温度皆有影响。非降水天气时,陆面感热通量占净辐射的主要部分。云和降水皆会直接影响陆面的能量分配,感热通量一般随云量的增加而减小,潜热通量则逐渐增大。湖面典型晴天的午后存在逆温现象,然降水天气时,湖面空气温度降低较快,破坏了湖面上空的逆温层,即感热通量皆为正值。湖面的潜热通量主要决定于风速,故其对天气变化响应不明显。在地下水携带的热量和局地平流共同作用下,湖面的感热通量和潜热通量之和大于湖面的净辐射。不同天气下陆面和湖面的波文比差异较大。陆面典型晴天的辐射收支和能量分配与季节平均气候态相差不大,湖面的典型晴天则不具有季节平均气候态的代表性。     

黄河源区草场近地面能量收支研究

基于玛多县环境梯度监测系统2009 年11 月至2010 年10 月观测数据,利用组合法计算黄河源区近地面的感热通量和潜热通量,进而分析近地面能量收支状况。结果表明：黄河源区年总辐射能量较高,达6.73×10⁹ J/m²,受积雪影响,反射率可超过0.5;在寒冷季节地面吸收的60%以上短波能量以辐射形式传给大气,而夏季则不到50%;地面全年吸收能量的80.5%以潜热形式支出,向地下深层传递的能量较少,仅占1.9%;不同月份的地表能量收支项差异较大,特别是寒冷季节。     

自然滩地型湖滨带陆向辐射带宽度界定研究

自然滩地型湖滨带是湖滨带修复的基本参照类型.自然滩地型湖滨带的陆向辐射带是其重要组成部分,是由湖泊最高水位线向陆域延伸一定范围的区域.陆向辐射带有水陆生态交错带的复杂性、过渡性,致使其宽度难以界定.为了探索自然滩地型湖滨带陆向辐射带宽度的界定方法,以太湖、长潭水库和下渚湖为例,基于对湖滨带空间结构特征的理解,以湿生草本植物的重要值计算平方欧氏距离（SED）,采用移动分割窗技术（MSWT）,界定上述湖泊自然滩地型湖滨带陆向辐射带宽度,并对影响宽度的因素进行分析.结果表明:太湖、长潭水库、下渚湖自然滩地型湖滨带陆向辐射带宽度分别为15~19、19~31、17~21 m.对陆向辐射带宽度与土壤理化性质、植物群落多样性进行相关性分析及冗余分析表明,自然滩地型湖滨带陆向辐射带宽度与土壤营养盐含量无明显相关性,与湖滨带坡度呈显著负相关（P < 0.01）,与土壤含水率呈显著正相关（P < 0.05）.研究显示:移动分割窗技术可用于界定自然滩地型湖滨带陆向辐射带宽度;土壤含水率是影响自然滩地型湖滨带陆向辐射带宽度的主要因素,陆向辐射带坡度通过影响土壤含水率,进而影响湿生草本植物分布,是自然滩地型陆向辐射带宽度的次要影响因素.      

Thermal based functional evaluation of urban park vegetation

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光合有效辐射总量及其散射辐射比例变化对 森林GPP影响的模拟

研究利用基于冠层辐射传输与植物生理过程的MAESTRA模型,结合中国东部鼎湖山、千烟洲及长白山3个典型森林生态系统的CO₂通量观测数据,对光合有效辐射(Photosynthetically Active Radiation, PAR)总量及其散射辐射比例变化影响下生态系统总初级生产力(Gross Primary Productivity,GPP)的变化进行了模拟与敏感性分析,从而探讨这两者的变化对森林生态系统GPP的综合影响。研究结果表明:PAR总量变化对GPP的影响程度由PAR总量变化幅度以及GPP对PAR总量变化的敏感程度所决定,较低的PAR总量与较高的温度条件下GPP对PAR总量变化较敏感;散射辐射比例增大可以提高森林冠层对入射PAR的吸收和利用效率,其对GPP的影响程度由散射辐射量的变化以及散射辐射与直射辐射在吸收与利用效率上的差别所决定,较高温度与叶面积条件下该差别较大;PAR总量与散射辐射比例共同变化对GPP的综合影响取决于上述两个过程的抵消结果,入射PAR较强时两者抵消作用通常更明显,在全年总量上,散射辐射比例变化对GPP的影响能抵消PAR总量变化影响的1/3~1/2。     

Fate of BHC in the terrestrial ecosystem

The fate of BHC in the terrestrial ecosystem was investigated under both laboratory and field conditions. The uptake, accumulation and degradation of BHC in earthworms and corn plants were studied. Earthworms could absorb and accumulate BHC residues from soil. Statistically, significant correlation existed between the amounts of BHC in soil and in earthworms. Different species of earthworms appeared to concentrate BHC in their bodies to different extents. In a terrestrial ecosystem, the uptake, accumulation of BHC residues by soil animals and plants had an effect on each other.     

中国农业植被净初级生产力模拟(I)——模型的建立与灵敏度分析

以业已建成的稻麦作物净初级生产力模型为基本框架,建立了一个具有普适性的中国农业植被净初级生产力模型(CropC-)。CropC-的模拟对象为占我国农作物总播种面积2/3的水稻、小麦、玉米、棉花、油菜和大豆。该模型包括2个主要功能模块:光合作用和呼吸作用;土壤-作物系统氮素运移。前者综合考虑了环境因子和氮素的影响,后者包括了作物氮素吸收、土壤氮矿化和化肥氮释放。灵敏度分析表明,在输入参数变化±10%时,CropC-对6个主要输入参数响应的敏感性依次为温度>光合有效辐射>大气CO2浓度>土壤全氮含量>施氮量>降水。模型分析表明,气候变暖将降低作物净初级生产力。     

中国农业植被净初级生产力模拟(I)——模型的建立与灵敏度分析

以业已建成的稻麦作物净初级生产力模型为基本框架,建立了一个具有普适性的中国农业植被净初级生产力模型(CropC-)。CropC-的模拟对象为占我国农作物总播种面积2/3的水稻、小麦、玉米、棉花、油菜和大豆。该模型包括2个主要功能模块:光合作用和呼吸作用;土壤-作物系统氮素运移。前者综合考虑了环境因子和氮素的影响,后者包括了作物氮素吸收、土壤氮矿化和化肥氮释放。灵敏度分析表明,在输入参数变化±10%时,CropC-对6个主要输入参数响应的敏感性依次为温度>光合有效辐射>大气CO2浓度>土壤全氮含量>施氮量>降水。模型分析表明,气候变暖将降低作物净初级生产力。     

气溶胶直接辐射效应对全球陆地生态系统碳循环的影响

论文利用通用陆面模式CLM4.0-CN对全球陆地生态系统生物地球化学循环过程进行模拟,分析气溶胶直接辐射效应对全球陆地生态系统碳循环的影响。结果表明：气溶胶直接辐射效应使2007年全球陆地生态系统平均总初级生产力（GPP）、净初级生产力（NPP）、异养呼吸（R_H）、自养呼吸（R_A）以及净生态系统生产力（R_eco）都呈现出增加的态势。具体的变化特征则随着地区不同而表现出极大的差异,在非洲中西部、中国中东部、美国东南部和欧洲中南部地区GPP增加,在南美洲亚马逊地区及东南亚等地区GPP减少。NPP和R_A与GPP的分布基本一致。分析发现,气溶胶直接辐射效应导致陆地生态系统碳循环发生变化有如下两方面原因： 1）散射施肥效应,即植被阴生叶可以吸收的散射辐射（光合有效辐射）增加使其光合速率增加;2）辐射变化导致温度和湿度条件发生变化,从而改变植物生物物理和化学过程速率。     

天然日光辐照下河口区CDOM的光化学降解

2005年5月初和5月末,对经0.2μm滤膜过滤的九龙江口低盐度水样进行了2次每天6h、为期1周的天然日光辐照实验,研究有色溶解有机物(CDOM)的荧光与吸收性质的光化学降解特征.结果表明, CDOM的类腐殖质荧光(λEx/λEm = 350/450nm)、类色氨酸荧光(λEx/λEm = 225/350nm)以及吸收系数在初夏短期日光辐照下均发生明显的光化学降解,其降解过程符合一级动力学方程,相应计算出类腐殖质和类色氨酸荧光以及吸收系数a(280)的半衰期分别为3.5～5.1 d、3.0～4.5 d及6.3 d.吸收损失光谱研究表明,对CDOM光降解起主要作用的是太阳辐射的紫外波段.照射42h后,类腐殖质荧光的损失(70%)远高于吸收系数a(280)的损失(约40%),表明CDOM荧光团比发色团更易被光漂白,但两者之间仍保持良好的正相关性.与对照组相比, CDOM经日光辐照后其A250/A350比值增大,表明光化学降解可使其平均分子粒径变小.结果表明, CDOM在入海后可通过光降解作用在近海海域发生转化及清除,光降解是陆源 CDOM 入海后的一个重要归宿.     

Growth and nutrient accumulation of Phragmites australis in relation to water level variation and nutrient loadings in a shallow lake

Shallow lake eutrophication is a global environmental issue. This study investigated the effects of water level variation and nutrient loadings on the growth and nutrient accumulation of Phragmites australis (reed) by field samplings in Baiyangdian Lake, the largest shallow lake of northern China. The field samplings were conducted in two sites of different nutrient loadings during the whole growth period of reeds, and three types of zones with different water depths were chosen for each site, including the terrestrial zone with water level below the ground, the ecotone zone with the water level varying from belowground to aboveground, and the submerged zone with water level above the ground. The result showed that reed growth was more limited by water level variation than nutrient loadings. The average stem lengths and diameters in terrestrial zones were about 26.3%-27.5% and 7.2%-12.0% higher than those in submerged zones, respectively. Similarly, the terrestrial status increased the aboveground biomass of reeds by 36.6%-51.8% compared with the submerged status. Both the nutrient concentrations and storages in the aboveground reeds were mainly influenced by the nutrient loadings in surface water and sediment rather than the water level variation of the reed growth environment, and the nutrient storages reached their maxima in late August or early September. It was observed that the maximum nitrogen storage occurred in the terrestrial zone with higher nutrient loadings, with the value of 74.5 g/m 2 . This study suggested that water level variation and nutrient loadings should be considered when using reeds to control and remediate eutrophication of shallow lakes.     

土壤碳淋溶流失研究进展

土壤碳的淋溶流失是指在水的作用下土壤中的碳沿着水文路径转移到水环境的过程。尽管这些流失量有限,却对陆地碳平衡核算具有重要影响。本文在总结了土壤碳淋溶流失研究的重要性、近年来相关领域取得的进展的基础上,指出已有研究的不足有:对土壤无机碳(SIC)的淋溶流失研究薄弱、缺乏野外实地观测、对土地利用变化影响土壤碳淋溶流失的过程与机制认识不足等。今后除了加强以上几个方面的研究外,还要综合利用同位素示踪和在线仪器观测等各种手段,开展"陆地-水生系统连续体"内多界面碳交换的综合研究。     

Surface albedo measurements at 53°N latitude

Albedo is a fundamental parameter in the energy budget equations used to estimate environmental quantities affected by solar radiation. Air pollution models require surface albedo values as an input to determine the magnitude of photochemical reaction rate constants. Eight years of albedo measurements in a northern, continental climate yield average monthly surface albedo values ranging from 0.17 in summer to 0.69 in winter. The pattern of variation throughout the day over a snow surface differs from that over a grass surface. Surface albedo makes a major contribution to the photochemical rate constants in the snow-covered winter months.     

Adaptation policies to increase terrestrial ecosystem resilience: potential utility of a multicriteria approach

Climate change is rapidly undermining terrestrial ecosystem resilience and capacity to continue providing their services to the benefit of humanity and nature. Because of the importance of terrestrial ecosystems to human well-being and supporting services, decision makers throughout the world are busy creating policy responses that secure multiple development and conservation objectives— including that of supporting terrestrial ecosystem resilience in the context of climate change. This article aims to advance analyses on climate policy evaluation and planning in the area of terrestrial ecosystem resilience by discussing adaptation policy options within the ecology-economy-social nexus. The paper evaluates these decisions in the realm of terrestrial ecosystem resilience and evaluates the utility of a set of criteria, indicators, and assessment methods, proposed by a new conceptual multi-criteria framework for pro-development climate policy and planning developed by the United Nations Environment Programme. Potential applications of a multicriteria approach to climate policy vis-à-vis terrestrial ecosystems are then explored through two hypothetical case study examples. The paper closes with a brief discussion of the utility of the multi-criteria approach in the context of other climate policy evaluation approaches, considers lessons learned as a result efforts to evaluate climate policy in the realm of terrestrial ecosystems, and reiterates the role of ecosystem resilience in creating sound policies and actions that support the integration of climate change and development goals.     

中国东部典型森林生态系统蒸散及其组分变异规律研究

森林蒸散包括植被蒸腾、土壤蒸发、冠层截留蒸发三个组分,在陆地生态系统水分循环及能量流动研究中占有重要地位。论文基于Priestley-Taylor Jet Propulsion Laboratory Model （PT-JPL）模型,估算温带针阔混交林、人工常绿针叶林、亚热带常绿阔叶林三个典型森林生态系统2003-2008年蒸散（组分）;在模拟结果基础上揭示了蒸散（组分）的季节变异规律及主控因子。结果表明：①PT-JPL模型在中国东部森林生态系统蒸散及其组分估算中具有较高的稳定性和可靠性;②蒸散（组分）季节变化特征明显,不同森林生态系统类型变化规律差异较小,但主控因子存在较大差异：温带针阔混交林蒸散和植被蒸腾季节变异主要由净辐射和增强植被指数（EVI）共同控制,而亚热带人工常绿针叶林和亚热带常绿阔叶林主要受净辐射影响;EVI和饱和水汽压差（VPD）是土壤蒸发季节变异的主控因子,截留蒸发的季节变化则主要受VPD影响。