岩溶区地表水体惰性有机碳研究

岩溶作用所产生的岩溶碳汇对全球碳循环有着重要的影响。岩溶水生生物通过CO₂富集机制（CCM）固定岩溶水中的HCO₃^-,将其转化为有机碳。惰性有机碳（RDOC）为水生生物和微生物不能利用和降解的溶解性有机碳。RDOC长时间滞留水体,形成稳定碳汇。多次培养实验发现可以用原位微生物法对岩溶区地表水中的RDOC进行检测。以桂林漓江为对象,研究由外源水补给并流经岩溶峰林平原区的岩溶地表水中的RDOC及其相关因子,结果显示：1）漓江水中Ca²⁺,HCO₃^-浓度从上游到下游逐渐升高,表明外源水进入岩溶区,发生了岩溶作用。漓江水的C/N为6.29~10.50,表明水中有机碳的来源为外源水和水生生物作用。受岩溶作用和水生生物光合作用双重影响,δ¹³C-DIC值从上游到下游逐渐偏正,水生生物优先利用无机碳中的¹²C使得δ¹³C-POC从上游到下游逐渐偏负。C/N与δ¹³C-DIC、δ¹³C-POC的变化以及相关性体现了岩溶地表水体中无机环境和有机环境相关联;2）岩溶区地表水中检测出RDOC且浓度远大于非岩溶区,RDOC浓度的时空变化与水生生物利用岩溶作用所产生的HCO₃^-有关。漓江地表水中DOC、BDOC、RDOC浓度与HCO₃^-浓度变化趋势一致,从上游到下游逐渐升高,下游L6（岩溶区）RDOC浓度为上游L1（非岩溶区）的3倍,在季节上表现出秋季>冬季>夏季>春季,RDOC的含量平均占水体中DOC含量的78%左右,体现了岩溶作用强度和水生生物活动对岩溶地表水中RDOC的影响;3）结合流量数据计算RDOC通量：桂林水文站RDOC的通量为0.75×10⁷ kg/a,阳朔水文站的RDOC通量为1.3×10⁷ kg/a,是桂林水文站断面的1.7倍。

     

吉林省西部沙化土地持续农业体系建立的实践

吉林省沙化土地的８７．９％分布在吉林省西部白城、松原半干旱地区，统属科尔沁和松嫩沙地，面积９２１６．５ｋｍ２，占吉林省西部总面积的１９．６％。８年（１９８６年～１９９３年）实践证明：针对沙地环境特点建立的“乔、灌、草”、“果、药、杂”、“田、林、草”为主体的三种持续农业体系效果明显。     

The atmospheric circulation patterns influencing the frequency of spring sand-dust storms in the Tarim Basin

Using NCEP/NCAR reanalysis data and the sand-storm frequency data fi＇om 37 weather stations in the Tarim Basin for the period 1961-2009, the relationship between the frequency of spring sandstorms in the Tafim Basin and the associated atmospheric circu- lation pattems is analyzed in this study. We found significantly negative correlations between sandstorm frequency and the 500-hPa geopotential height over the Paris Basin and midwestem Mongolia, while there were positive correlations over the Ural River region. The rising of the 500-hPa geopotential height in midwestem Mongolia and its falling over the Ural region corre- spond to a weakening of the large-scale wave patterns in the Eurasian region, which directly causes the frequency of the sand-dust storms in the Tarim Basin to decline. Also, the abrupt decline in the spring sandstorm frequency in the Tarim Basin observed in the last half-century is associated with profound changes in the atmospheric circulation in these key regions. At the interannual scale, the strengthened cyclonic atmospheric circulation patterns in the western part of Mongolia and the anticyclonic patterns over the East European plains at 500-hPa geopotential height, are responsible for frequent sandstorm occurrences in the Tarim Basin.     

Tracking Solar Active Region Outflow Plasma from Its Source to the Near-Earth Environment

Seeking to establish whether active-region upflow material contributes to the slow solar wind, we examine in detail the plasma upflows from Active Region (AR) 10978, which crossed the Sun’s disc in the interval 8 to 16 December 2007 during Carrington rotation (CR) 2064. In previous work, using data from the Hinode/EUV Imaging Spectrometer, upflow velocity evolution was extensively studied as the region crossed the disc, while a linear force-free-field magnetic extrapolation was used to confirm aspects of the velocity evolution and to establish the presence of quasi-separatrix layers at the upflow source areas. The plasma properties, temperature, density, and first ionisation potential bias [FIP-bias] were measured with the spectrometer during the disc passage of the active region. Global potential-field source-surface (PFSS) models showed that AR 10978 was completely covered by the closed field of a helmet streamer that is part of the streamer belt. Therefore it is not clear how any of the upflowing AR-associated plasma could reach the source surface at 2.5 R_⊙ and contribute to the slow solar wind. However, a detailed examination of solar-wind in-situ data obtained by the Advanced Composition Explorer (ACE) spacecraft at the L₁ point shows that increases in O⁷⁺/O⁶⁺, C⁶⁺/C⁵⁺, and Fe/O – a FIP-bias proxy – are present before the heliospheric current-sheet crossing. These increases, along with an accompanying reduction in proton velocity and an increase in density are characteristic of both AR and slow-solar-wind plasma. Finally, we describe a two-step reconnection process by which some of the upflowing plasma from the AR might reach the heliosphere.     

The evolution of the z distribution of normal neutron stars in the Galaxy

Under the two initial 1‐D one parameter velocity distribution forms (one is normal, the other is exponential), the z direction scale height evolution of normal neutron stars in the Galaxy is studied by numerical simulation. We do statistics for the cases at different time segments, also do statistics for the cumulative cases made of each time segment. The results show in the cumulative cases the evolution curves of the scale heights are smoother than in the each time segment, i.e., the cumulation improve the signal‐to‐noise ratio. Certainly the evolution cases are different at different Galactic disk locations, which also have very large difference from the average cases in the whole disk. In the initial stages of z evolution of normal neutron stars, after the beginning transient states, the cumulative scale heights increase linearly with time, and the cumulative scale height increasing rates have linear relationship with the initial velocity distribution parameters, which have larger fluctuation in the vicinity of the Sun than in the whole disk. We utilize the linear relationship of the cumulative scale height increasing rates vs. the initial velocity distribution parameters in the vicinity of the Sun to make comparison with the observation near the Sun. The results show if there is no magnetic decay, then the deserved initial velocity parameters are obvious lower than the present well known results from some authors; whereas if introducing magnetic decay, for the 1‐D normal case we can make consistence among concerning results using magnetic decay time values which are supported by some authors, while for the 1‐D exponential case the results show the lackness of young pulsar samples in the larger z in the vicinity of the Sun (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

关于对龙居镇宅基用地情况的调查

农村居民点用地是非农业建设用地的重要组成部分,加强农村居民点用地管理,对稳定耕地面积,实现耕地总量动态平衡有着十分重要的意义。为了更全面地了解农村宅基用地的现状、存在的问题,寻求解决问题的途径,龙居镇国土资源所对全镇有代表性的8个村庄的农村宅基用地问题进行了调研。     

Rapid exhumation of basement rocks along the northern margin of the North China craton in the early Jurassic: evidence from the Xiabancheng Basin,Yanshan Tectonic Belt

Early Mesozoic Basins in the Yanshan Fold–Thrust Belt (YFTB), located along the northern margin of the North China Craton (NCC), record significant intraplate deformation of unknown age. In this article, we present evidence for the rapid exhumation of high‐grade basement rocks along the northern margin of the NCC in the Early Mesozoic. U–Pb geochronology of detrital zircons constrains the maximum depositional ages of syntectonic sedimentary units that formed during the unroofing of basement rocks and plutons in the Xiabancheng Basin. In the Early Mesozoic, the Xiabancheng Basin recorded a dramatic transformation in depositional environments, related to a significant change in the regional tectonic setting. In this study, the tectonic evolution of the YFTB is established from paleocurrent data and U–Pb zircon ages of sandstone and granitic gravels of the Xingshikou Formation, Xiabancheng Basin. The paleocurrent direction of meandering fluvial facies in the Triassic Liujiagou and Ermaying Formations are from east to west. In contrast, the overlying Xingshikou Formation consists of alluvial fan facies with paleocurrent directions from north‐northwest to south‐southeast. The lower and middle segments of the Xingshikou Formation record rapid exhumation of basement rocks along the northern margin of the NCC. U‐Pb ages of detrital zircons within the Xingshikou Formation are characterized by three major U–Pb age groups: 2.2–2.5 Ga, 1.7–1.8 Ga and 193–356 Ma. From 193 Ma to 356 Ma, a subsidiary peak occurs at 198 ± 5 Ma, constraining the sedimentation age of the Xingshikou Formation to the Early Jurassic. Zircon from the Wangtufang pluton in the northern portion of the Xiabancheng Basin yields U–Pb ages of 191 ± 1 Ma and 207 ± 1 Ma. Within error, these crystallization ages are identical to detrital zircon ages of 206 ± 1 Ma and 206 ± 2 Ma obtained for granitic gravel clasts in the Xingshikou Formation. Thus, the Wangtufang pluton and surrounding basement rocks must have experienced rapid uplift and exhumation during the Early Jurassic. The onset of exhumation along the northern margin of the NCC occurred at ca. 198–180 Ma.     

沙漠下垫面地面温度及能量收支的BATS模式参数化改进

利用陆面过程模式BATS,引入地表发射率及两种大气发射率参数化方案,同时引入不同的地表粗糙度参数化方案,对比各种参数化方案对沙漠下垫面地面温度及能量收支的模拟状况。结果表明：采用Van Bavel等发展的地表发射率及Chung等发展的大气发射率方案可以明显改进地面温度及向上长波辐射的模拟,Chung等方案在夜间与正午的模拟效果更好,减小了1 ℃左右的地面温度模拟偏差,减小了10 W·m^-2左右的向上长波辐射模拟偏差。晴天地面温度及向上长波辐射的模拟结果优于阴天。利用Zhang等发展的裸土粗糙度参数化方案也会提高模式对地表感热通量模拟的准确性。     

The fronts of the Huanghai cold water mass (HCWM) induced by tidal mixing

Since Simpson and Hunter proposed in 1971 the idea that shallow water fronts were induced by tidal mixing, many authors have investigated the tide induced shallow water fronts in various areas. It was generally assumed that a critical value of the stratified parameterK=log₁₀(H/U ³) may be used to identify the location of these fronts. Here, H means the depth of sea waler. U denotes the characteristic velocity of tidal current. and the critical value ofK is generally laken as 1.8–2.0. In this paper. Simpson-Hunter’s stratified parameterK was calculated by using quasi-maximum current velocity (which consists of the six main tidal constituents. i.e.M ₂.S ₂,O ₁.K ₁.M ₄,MS₄) in the H ranghai Sea (Yellow Sea) and in the northern Donghai Sea (East China Sea) as well. Caleulated results show that the areas of the Subei (the northern part of Jiangsu) Shoal. the area off the mouth area of the Changjiang (the Yangtze) River, along the coast of Shandong Peninsula. and along the western coast of Korea, the tidal mixing is strong. Calculations also show that along the whole boundary of the HCWM and also along the western boundary of the cyclonic eddy in the northern Donghai Sea, i.e. along the fronts, the value ofK is found to be very close to the eritical value 1.8. It is also to be noied that at these locations, the temperature of the surface water is very low. These clearly show that shallow water fronts in the Huanghai Sea and in the northern Donghai Sea as well, are induced by tidal mixing. Contribution No. 1241 from Institute of Oceanology, Academia Sinica. This paper was published in Chinese in theOcean. et Limn. Sinica 16(6): 451–459, 1985.