影响C₄草本植物C/N比值变化的因素与土壤有机C积累的关系   总被引：6，自引：1，他引：6       下载免费PDF全文

朴河春  朱建明  余登利  冉景丞 《第四纪研究》2004,24(6):621-629

文章对采自贵州从低海拔的东部到高海拔的西部且大致平行的石灰岩和砂岩两地带均生长的3种C₄草本植物,即巴茅(Miscanthusfloridulus)、白茅(Imperatacylindrica)和类芦(Neyraudiareynaudiana),以及相对应的土壤表层样品,进行了营养元素和C同位素组成分析;研究营养元素含量随着海拔的不同而出现的变化趋势,以及这些元素之间的相互协变作用,尤其是Ca和N之间的相互协变作用对植物的N含量、C/N比值和^δ13C值的影响,以了解植物的C/N比值(指示植物残留物质量的一种标志)与土壤有机C积累的关系。研究结果表明,植物的N含量和^δ13C值具有随海拔的上升而显著增大趋势,而植物的C/N比值在砂岩地区虽有减小的趋势,在石灰岩地带则没有。对所研究的C4草本植物来说,在土壤pH值为5.8的中性条件下显示出Ca的最大吸收,因此,Ca与其他营养元素之间的协变模式在两种土壤类型中表现出相反的倾向,并存在土壤交换性Ca的边界浓度:当土壤可交换性Ca的含量为2.24mg/g,相应土壤的pH值在5.8以下时,随着土壤可交换性Ca浓度的增大,植物的N含量上升,而植物的C/N比值会显著降低;当Ca在边界浓度以上时,随着土壤可交换性Ca浓度的增大,植物的N含量下降,而植物的C/N比值有增加的趋势。由此可见,植物残留物的N含量和C/N比值受Ca元素含量的相  相似文献   

Methane-rich fluid inclusions in skarn near the giant REE–Nb–Fe deposit at Bayan Obo, Northern China     

Hong-Rui Fan  Yi-Han Xie  Kai-Yi Wang  Simon A. Wilde 《Ore Geology Reviews》2004,25(3-4):301-309

We report fluid inclusion data for skarn, formed at the contact between Hercynian granitoids and dolomite of the Proterozoic Bayan Obo Group, in the vicinity of Bayan Obo REE–Nb–Fe deposit, Inner Mongolia, China. Three types of fluid inclusions are identified: two-phase CH₄-rich, three-phase liquid–vapour–solid and two-phase aqueous inclusions. Using microthermometry and laser Raman microprobe analysis to calculate isochores for CH₄-bearing inclusions, we estimate fluid trapping conditions at T=280 to 344 °C and P<1 to 2.3 kbar. Such conditions are compatible with formation of CH₄ inclusions as a result of reaction between graphite in the country rocks (black slate sequence) and fluids derived from magma. The lack of carbonaceous material in the inclusions supports the hypothesis that CH₄ was generated during fluid migration rather than by in situ reaction. In contrast to the skarn, and despite the fact that similar graphite-bearing slates are found in the host rocks, no CH₄-bearing inclusions have been so far reported from Bayan Obo REE ores. We therefore conclude that the skarn-forming fluids in the contact aureole of the Hercynian granitoids were not involved at any stage in the formation of the Bayan Obo deposit.  相似文献   

洛川黄土剖面中矿物固定态铵的分布   总被引：1，自引：2，他引：1  

饶文波  李晓彪  高振敏  罗泰义 《中国沙漠》2004,24(6):685-688

对洛川黄土中的固定铵进行了初步分析。结果表明,在所测定的黄土古土壤层中,固定铵态氮含量在130-1之间变化。黄土中的固定铵态氮含量明显低于古土壤。13万a以来洛川黄土剖面中固定铵的分布呈～210现三次大的低高值的振荡特征,即末次间冰期S1古土壤中固定铵态氮含量最高,其次为冰后期的S0古土壤层,末次冰期形成的马兰黄土中固定铵态氮含量最低;在马兰黄土中同样体现出三次小的低高值的波动特征。黄土与μm组分的分布具有相似性,这些特征反映了洛川黄土中固定铵态氮的含量变化与气互层的古土壤中固定态铵的分布与黄土高原区气候的冷暖变化有较好的一致性,并且13万a以来洛川黄土剖面中固定铵的分布与磁化率和<2候条件有紧密的联系,揭示了黄土中固定铵的变化在一定程度上能指示黄土高原区古气候的演变。  相似文献   

Continuous Multi‐probe Measurements in Fastflowing Waters Using a Hydrographic Slot     

Bernhard Karrasch  Michael Herzog 《洁净——土壤、空气、水》2005,33(2):165-169

Taking continuous spatiotemporal in situ measurements with multi‐probes in fast‐flowing waters/rivers can be problematic because the sensors may be damaged by high shear forces and flotsam. To protect the multi‐probe and to enable easy access for the maintenance and calibration of the sensors, a special multi‐probe holder fixed in a hydrographic slot was developed. The validation of the probe system revealed a “memory effect” at short time scales (< 10 s) within sharp gradients caused by the overflow container of the multi‐probe rack keeping the sensors submerged in the sample water. Continuously recorded data (conductivity, temperature, pH, oxygen concentration and saturation, as well as in vivo fluorescence of chlorophyll‐a) from a research cruise on board the RV ALBIS along the river Elbe (river km 309) and entering the river Saale are presented. This river stretch upstream of the city of Magdeburg to the mouth of the Saale tributary was found to have a complex physicochemical character, which is attributable to the long mixing process of water from the river Saale and the river Elbe.  相似文献   

Sorption of carbon dioxide–methane mixtures     

Grayna Ceglarska-Stefa&#x;ska  Katarzyna Zar&#x;bska 《International Journal of Coal Geology》2005,62(4):211-222

The paper reports the results of experiments concerning the sorption/desorption processes, observed under laboratory conditions, in two types of coal extracted from operational coal-mines in Poland, using CH₄ and CO₂ to observe their relative inter-reaction with the coal samples when introduced in varying proportions and conditions. Numerous studies concerning the sorption/desorption phenomena have described the operational mechanisms and the relationship of mine gases to the organically-created coal-body in mines. The differences in the behaviour of certain gases is twofold: firstly the essentially different characteristics of CO₂ and CH₄, and secondly the structure of the coal-bed itself: its degree of metamorphism and content of macerals. From the results yielded, it was observed that the divergence of the isotherms of sorption of CH₄ and other gases in comparison with the isotherms of sorption of CO₂ and a CO₂/CH₄ mixture differed and that the curve on the sorption isotherm was more clearly distinct after the introduction of CO₂ molecules to the system: coal with a higher degree of metamorphism—CH₄, which is closely related to the rigidity of the structure according to the level of metamorphism. Since coals with higher carbon content exhibit lower molecular bonding than low-carbonised coals, the characteristic feature of the bonds in the first case is their mobility. Knowledge of the physical and chemical properties of hard coals, as well as their interaction with mining gases, is of great use in solving problems concerned with the extraction of methane from mines or its storage in goafs.  相似文献   

Environmental significance of C/C and O/O ratios of modern land-snail shells from the southern great plains of North America     

Meena Balakrishnan  James L. Theler  Don G. Wyckoff 《Quaternary Research》2005,63(1):15-30

¹³C/¹²C and ¹⁸O/¹⁶O ratios of aragonite shells of modern land snails from the southern Great Plains of North America were measured for samples from twelve localities in a narrow east-west corridor that extended from the Flint Hills in North Central Oklahoma to the foothills of the Sangre de Cristo Mountains in Northern New Mexico, USA. Across the study area, shell δ¹⁸O values (PDB scale) ranged from −4.1‰ to 1.2‰, while δ¹³C values ranged from −13.2‰ to 0.0‰. δ¹⁸O values of the shell aragonite were predicted with a published, steady state, evaporative flux balance model. The predicted values differed (with one exception) by less than 1‰ from locality averages of measured δ¹⁸O values. This similarity suggests that relative humidity at the time of snail activity is an important control on the δ¹⁸O values of the aragonite and emphasizes the seasonal nature of the climatic information preserved in the shells. Correlated δ¹³C values of coexisting Vallonia and Gastrocopta suggest similar feeding habits and imply that these genera can provide information on variations in southern Great Plains plant ecology. Although there is considerable scatter, multispecies, transect average δ¹³C values of the modern aragonite shells are related to variations in the type of photosynthesis (i.e., C₃, C₄) in the local plant communities. The results of this study emphasize the desirability of obtaining isotope ratios representing averages of many shells in a locale to reduce possible biases associated with local variations among individuals, species, etc., and thus better represent the “neighborhood” scale temporal and/or spatial environmental variations of interest in studies of modern and ancient systems.  相似文献   

273.15K下LiCl-Li2B4O7-H2O体系热力学性质的等压研究   总被引：2，自引：0，他引：2       下载免费PDF全文

杨吉民  姚燕  张爱云  宋彭生 《盐湖研究》2005,13(1):19-24

用等压法研究了273 15K下LiCl-Li2B4O7-H2O体系中纯盐水溶液(离子强度范围为LiCl0 2046～2 5055mol·kg-1,Li2B4O70 1295～0 3700mol·kg-1)以及混合盐水溶液(离子强度范围为0 0931～2 4911mol·kg-1)渗透系数和水活度;计算了LiCl-Li2B4O7-H2O体系的饱和蒸汽压,获得饱和蒸汽压、渗透系数随离子强度的变化规律。用实验数据以最小二乘法求取了LiCl和Li2B4O7纯盐参数及体系的混合盐参数,拟合的标准偏差分别为0 0077和0 026。用该模型计算的渗透系数值与实验结果取得合理的一致。同时研究结果与273 15K下LiCl-Li2SO4-H2O体系的渗透系数随离子强度变化的规律作了比较。本研究对完善低温下含锂、硼盐湖卤水体系的热力学模型和盐湖资源的综合开发利用具有重要意义。  相似文献   

浓硫酸钠水溶液中的离子对          下载免费PDF全文

刘元会  房春晖 《盐湖研究》2005,13(4):42-46

不同浓度的Na2SO4水溶液的拉曼光谱显示了SO42-的四个拉曼活性带:980 cm-1处的SO42-的对称伸缩振动模式v1带,1 106 cm-1处的反对称伸缩振动模式v3带,448 cm-1处的变形振动模式v2带和617 cm-1处的变形振动模式v4带。482 cm-1处的肩膀峰是由于NaSO4-离子对的形成对448 cm-1的v2带的影响而形成的SO42-的一个新的振动峰。浓Na2SO4水溶液中,水共享离子对[Na+.H2O.SO42-]-是主要的离子对物种。随着Na2SO4水溶液浓度的增加,Na+和SO42-的相互作用增强,NaSO4-离子对所占的摩尔分数增加。  相似文献   

Urban stormwater thermal gene expression models for protection of sensitive receiving streams          下载免费PDF全文

A.M.A. Sattar  B. Gharabaghi  F. Sabouri  A.M. Thompson 《水文研究》2017,31(13):2330-2348

Thermal impact of typical high‐density residential, industrial, and commercial land uses is a major concern for the health of aquatic life in urban watersheds, especially in smaller, cold, and cool‐water streams. This is the first study of its kind that provides simple easy‐to‐use equations, developed using gene expression programming (GEP) that can guide the assessment and the design of urban stormwater management systems to protect thermally sensitive receiving streams. We developed 3 GEP models using data collected during 3 years (2009–2011) from 4 urban catchments; the first GEP model predicts event mean temperature at the inlet of the pond; the second model predicts the stormwater temperature at the outlet of the pond; and the third model predicts the temperature of the stormwater after flowing through a cooling trench and before discharging to the receiving stream. The new models have high correlation coefficients of 0.90–0.94 and low prediction uncertainty of less than 4% of the median value of the predicted runoff temperatures. Sensitivity analysis shows that climatic factors have the highest influence on the thermal enrichment followed by the catchment characteristics and the key design variables of the stormwater pond and the cooling trench. The general method presented here is easily transferable to other regions of the world (but not necessarily the exact equations developed here); also through sensitivity and parametric analysis, we gained insight on the key factors and their relative importance in modelling thermal enrichment of urban stromwater runoff.  相似文献   

Pix4Dmapper在无人机航摄应急救灾项目中的应用研究   总被引：2，自引：0，他引：2  

汪雅婕 《测绘与空间地理信息》2016,(9):202-203

无人机由于其独特的航摄优势,在灾害应急处理等特殊事件中,发挥着越来越重要的作用。本文结合一次山体滑坡救灾项目,阐述了使用Pix4Dmapper软件对无人机航摄数据进行快速处理,并获取正射影像图和数字表面模型的方法,通过数据分析和评估,证明了此方法的可行性和有效性。  相似文献