The input／removal rates of size-fractionated ^210Po in the Jiulongjiang estuary and its implications

O, S, Se, Te and Po are the elements of the VIB.210Po (T1/2=138.4 d, Ea=5.3044 MeV) has strong affinities to particles, especially particulate organic matter (POM), thus 210Po in seawater can be transported into the sediment by scavenging and removal, and the disequilibria between 210Po and 210Pb become a methodological base for the study of the particle dynamic processes in marine envi-ronments with the time scale of years to a centenary. The concentration, inventory and geochemical be…     

^210Pbex depth distribution in soil and calibration models for assessment of soil erosion rates from ^210Pbex measurements

Throughout the past decade, the potential for using nuclear weapon-produced 137Cs ( half-life 30.2 a) fallout to quantify soil erosion rates on both cultivated and uncul- tivated lands for medium-term timescales (≈ 40 a) has been successfully demonstrated in a wide range of envi- ronments in different regions of the world[1—6]. Because in difficulties of distinguishing Chernobyl-derived compo- nent from total 137Cs input in many parts of Europe, and in measuring low activity samples of…     

苏干湖沉积物纹层计年和^210Pb，^137Cs测年对比

通过对西北干旱区苏干湖表层沉积物的年纹层计数定年和^210Pb,^137Cs测年结果对比发现：均^137Cs测年结果在8．5cm出现最高蓄积峰,对应1963年世界核爆高峰期,但在同一层位^210Pb测年结果则是1972年,存在较大的偏差．年纹层沉积速率达0．31cm／a,而根据CRS模式建立的^210Pb沉积速率为0．30cm／a．年纹层反映的沉积速率和^210Pb测年结果基本一致,互相验证了两者测年的可靠性．^137Cs测年则存在蓄积峰向上迁移的现象,在西北干旱区湖泊使用^137Cs测年过程中需引起注意．     

厦门地区^7Be和^210Pb的大气沉降通量

^7Be和^210Pb是大气中天然存在的放射性核素．本文测定了2001年8月至2002年8月间厦门地区^7Be和^210Pb大气沉降通量，平均值分别为1．90和0.41Bq m^-2d^-1．对^7Be和^210Pb的沉降特征及其影响因素进行了探讨，表明降雨是影响沉降通量的主要因素，两个核素的沉降通量之间存在较好线性相关性．     

^7Be and ^210pb radioactivity and implications on sources of surface ozone at Mt. Waliguan

Beryllium-7 (^7Be) and lead-210 (^210Pb) radioactivity in aerosols collected, from October 2002 to January 2004 at Mt. Waliguan, by the Global Atmospheric Watch (GAW) Station, Qinghai Province is presented. The data were analyzed together with simultaneously measured surface ozone concentrations. We found that short time variations of ^7Be and ^210Pb were linked to alternations of synoptic weather around the Mt. Waliguan region. ^210Pb showed the lowest concentration in summer while ^7Be showed no obvious seasonal changes. Relatively high ^7Be and ^210Pb radioactivity was observed at Mt. Waliguan when compared with the observations at other mountain sites in other parts of the world. Surface ozone and ^7Be showed a consistent seasonal variation. Surface ozone correlated fairly well with ^7Be/^210Pb ratio. This suggested that vertical transport from higher altitudes of the atmosphere has predominant effects on the budget of surface ozone at Mt. Waliguan.     

放射性^210Pb方法的地理学应用实例

利用岩芯放射性￣（２１０）Ｐｂ的实验数值推算潮滩的沉积率，沉积率数值与潮滩淤长的真实速率一致。￣（２１０）ｐｂ方法是推算近１００ａ内沉积物堆积速率的有效方法。     

Isotopic composition of organic carbon and elemental carbon in PM2.5 in Hangzhou, China

In order to identify the sources of organic carbon (OC) and elemental carbon (EC) in airborne PM2.5 in Hangzhou, OC and EC were oxidized to CO2 offline in two thermal steps, and their carbon isotope compositions were measured by mass spectrometer. Results showed that the average δ13COC values were -52.8‰, -48.1‰, -50.0‰ and -52.5‰ in spring, summer, autumn, and winter, respectively, and the annual average value was -50.9‰ (-85.0‰ to -35.6‰), whereas δ13CEC values were -26.4‰, -26.9‰, -26.7‰ and -25.9‰ in the four seasons, and its annual value was -26.5‰ (-30.5‰ to -23.8‰). Large differences were found between isotope compositions of the two types of carbon. δ13COC values were much smaller than those of δ13CEC, and varied in a large range, and the ratios in both spring and winter were the smallest. δ13CEC varied in a small range, and its mean values in four seasons were nearly the same. This suggests that the carbon isotope compositions of OC and EC in PM2.5 can provide useful information in distinguishing their sources.     

试析19世纪末20世纪初我国学校化学教育

19世纪末 20世纪初,随着西学东进,化学即已传入我国,为我国化学教育开辟了新纪元.了解和研究这一历史阶段化学教育的发展,对我国化学教育体系的发展和完善有着重要的意义.就 19世纪末 20世纪初我国学校化学教育的发展脉络进行了梳理与简要分析.     

Comparison of the carbon isotope composition of total organic carbon and long-chain n-alkanes from surface soils in eastern China and their significance

Surface soil samples collected over a high spatial resolution in eastern China were analyzed for carbon isotope composition(δ 13C) of total organic carbon(TOC) and higher plant-derived long-chain n-alkanes,with the latter reported as weighted mean values.The two sets of δ 13C values are significantly correlated and show similar trends in spatial variation.The spatial distribution of δ 13C shows less negative values in the mid-latitudes between 31°N and 40°N and more negative ones at higher and lower latitudes.This is consistent with previously reported carbon isotope data from surface soil phytoliths in the same region and suggests that the mid-latitude area provides relatively favorable growing conditions for C4 plants.Furthermore,δ 13C values of both TOC and long-chain n-alkanes from 12 surface soil samples collected from a small grassland in north China displayed similar carbon isotope values and the difference between paired δ 13C of a soil samples remains relatively constant.Our data demonstrate that in eastern China,soil δ 13C composition of both TOC and long-chain n-alkanes is effective indicators of C3/C4 ratios of the prevailing vegetation.This work suggests that -22‰ and -32‰ are good estimated end members for the weighted mean δ 13C values of long-chain n-alkanes(C27,C29 and C31 n-alkanes) from soils under dominant C4 or C3 vegetation,allowing us to reconstruct paleovegetation trends.     

基于C/S环境的远程数据访问技术

本文探讨了基于Ｃ／Ｓ环境的ＶＦＰ远程数据访问技术,结合实例给出了ＶＦＰ的实现方式     

珠江三角洲全新统横栏组淤泥沉积中的有机碳、总氮和碳氮比值记录

对广州番禺区ZK5孔中全新统横栏组淤泥沉积进行了总有机碳，总氮含量和碳氮比值分析。根据其变化可划分2个不同的沉积环境阶段，阶段Ⅰ（15.8-9.0m)的总有机碳含量变化幅度较大，总氮含量很低，碳氮比值较高。表明其有机质以陆源为主，有机质生产力明显受气候的控制，阶段Ⅱ（9-1.4m)总有机碳和总氮含量上升，变化较小，而碳氮比值下降，表明其主要受海洋的影响，有机质主要来源于原地浮游生物。     

土壤中碳酸钙和有机碳测定的一种新方法

利用阿曼苏丹国的一千多个土壤样品,对土壤中碳酸钙和有机碳测定的实验方法进行了研究。发现实际碳酸钙的含量可由“亚稳态”时碳酸钙含量乘以适当的因子代替,从而大大提高了工作效率。而利用有机碳/全氮(C/N)的特殊规律,则可建立一个确定“有机碳”实验中所需土壤样品量的新方法。     

长江水下三角洲YD0901孔记录的全新世以来的古环境信息

分析长江水下三角洲YD 0901孔的粒度、TOC(总有机碳)和TN(总氮),建立全新世以来高分辨率年代地层图(平均分辨率为20a).结果显示,\"中全新世大暖期\"(距今7ka～6ka)水下三角洲加速营造,同时闽浙泥质区开始缓慢形成.TOC和TN测试数据表明:在距今2.7ka左右,YD0901孔的TN含量逐渐增加,说明流域人类活动逐渐加剧;而TOC由于部分的成岩作用,含量并未明显增加.通过沉积相分析,得到最大海侵面的深度,为准确估算冰后期最大海侵以来水下三角洲沉积总量提供了可靠依据.     

粤东五华河悬浮颗粒有机质的组成及输出通量

河流碳输出过程构成全球碳循环的一个重要环节。基于一个完整水文年的月周期性采样分析,讨论了五华河径流中悬浮颗粒有机质(POM)的性质及其来源,估算了流域有机质的输出通量。结果表明:五华河径流中颗粒有机碳(POC)和颗粒有机氮(PON)的平均含量分别为0.77 mg/L和0.12 mg/L,其中汛期含量高于枯水期;五华河河流总悬浮颗粒物(TSS)、POC、PON含量以及河流颗粒有机质C/N比与流量的关系揭示五华河径流中POM主要源自流域土壤有机质的侵蚀,而且在迁移过程中受到水体微生物的分解;五华河流域POC和PON年输出通量分别为430 kg/(km2·a)和70 kg/(km2·a),其中汛期POC和PON输出量分别占全年输出总量的74.23%和76.17%。