UV-VUV excited luminescence of SrBPO5 : Sm phosphor prepared in air

The high-resolution luminescent spectrum of divalent samarium excited by 355 nm UV light at 77 K, the VUV excitation spectra, the VUV excited emission spectra and EXAFS at Sm-L-3 edge were reported for samarium doped strontium borophosphate, SrBPO5:Sm prepared by solid state reaction in air at high temperature. The high-resolution luminescent spectrum showed that the divalent samarium ions occupied the C-2upsilon lattice sites. The VUV excitation spectra indicated that the sample exhibited absorption bands with the maxima at 129 and 148 nm, respectively. The performance of EXAFS at Sm-L3 absorption edge suggested that the samarium ions were nine-coordinated and the mean distances of bond Sm-O were 2.38 Angstrom.

Preparation of divalent rare earth ions in air by aliovalent substitution and spectroscopic properties of Ln(2+)

When alkaline earth ions in borates, phosphates or borophosphates [SrB4O7, SrB6O10, BaB8O13, MBPO5 (M=Ca,Sr)] are substituted partially and aliovalently by trivalent rare earth ions such as Sm3+, Eu3+, these rare earth ions can be reduced to divalent state by the produced negative charge vacancy V-M". The matrices must have appropriate structure containing a rigid three-dimensional network of tetragonal AO(4) groups (A=B,P). These groups can surround and isolate the produced divalent RE2+ ions from the reaction with oxygen. Therefore, this reduction reaction can be carried out even in air at high temperature. The produced divalent rare earth ions can be detected by luminescence and XANES methods and their spectroscopic properties are discussed.

Preparation of borates doped with divalent rare earth ions (RE2+) in air and spectroscopy of divalent rare earth ions (RE2+ = Sm, Eu, Tm, Yb)

The spectroscopic feature of divalent Sm2+, Eu2+, Tm2+ and Yb2+ is discussed in this paper. Especially the spectroscopic properties of some berates containing tetrahedral BO4 group such as SrB4O7, SrB6O10 and BaB8O13 doped with these divalent ions are reported. When the divalent alkaline earth ion in these berates is replaced partially by the above trivalent rare earth ion, the charge carried in the produced defects can be used as reductant to reduce the doped rare earth ion into divalent state at high temperature even in air. Therefore, a convenient and safe method is provided to prepared phosphors doped with these divalent rare earths.

Luminescence of RE2+ (RE = Sm, Yb) in barium octoborate

The reduction process from trivalent to divalent state for Sm3+ and Yb3+ ions in barium berates (BaB8O13) prepared in air was observed. The luminescence properties of these divalent rare-earth ions were studied. Yb2+ shows an f-d broad emission band, due to the 4f(14) --> 4f(13)5d transition, while the Sm2+ ion shows an f --> f transition. From the spectra of Yb2+, and using the D-5(0) --> F-7(0) transition of Sm2+ as a structural probe, two crystallographic sites were found to be available for the cations in the host. Vibronic transitions of Sm2+ were observed at low temperature. BaB8O13 was found to be a good host for reducing the trivalent rare-earth ions to divalent state and to exhibit interesting spectroscopic properties,

The reduction of RE3+ in SrB6O10 prepared in air and the luminescence of SrB6O10 : RE2+ (RE=Eu, Sm, Tm)

The reduction of RE3+ to RE2+ (RE=Eu, Sm and Tm) in SrB6O10 prepared in air by high-temperature solid state reaction was observed. The luminescent properties of Eu2+ and Tm2+ show f-d transition and Sm2+ shows f-f transition at room temperature. Three crystallographic sites for Sm2+ in matrix are available. Vibronic transition of D-5(0)-F-7(0) of Sm2+ was studied. The coupled phonon energy about 108 cm(-1), was determined: from the vibronic transition. Due to the thermal population from D-5(0) level, (D1-FJ)-D-5-F-7 (J=0, 1, 2) transitions of Sm2+ were observed at room temperature. A charge compensation mechanism is proposed as a possible explanation.

Luminescence properties of Sm2+ in barium octaborates (BaB8O13 : Sm2+)

The luminescence of Sm2+ in BaB8O13 are studied as a function of temperature. At 10 K, several crystallographic sites for Sm2+ ions with inversion symmetry are possible and D-5(0) --> F-7(1) transition show predominant intensities, whereas above 50 K two crystallographic sites without inversion symmetry are clearly observed for Sm2+ in BaB8O13 and the D-5(0) --> F-7(0) transition show strongest intensity. The vibronic transitions and the non-radiative transitions of Sm2+ are studied and a coupled-phonon energy about 50 cm(-1) is obtained. The thermal effects on the line shift, emission intensities, half-width and lifetime of the D-5(0) --> F-7(0) transition are also studied. The decay curves at different temperatures are all in single exponential and are temperature-independent with lifetime around 3.5 ms. (C) 1999 Elsevier Science B.V. All rights reserved.

STUDIES ON THE REACTION AND STRUCTURE OF THE COMPLEXES OF ALKALINE-EARTH METAL WITH CHLOROPHOSPHONAZO-DBC

In this paper, the reaction and structure of the complexes of alkaline earth metal (Ca, Sr, Ba) with 2-(4'-chloro-2'-phosphonazo)-7-(2', 6'-dibromo-4'-chlorophenylazo 1, 8-dihydroxy-3, 6-naphthalene disulfonic acid (Chlorophosphonazo-DBC) have been studied. This ligand has eight forms under different acidity. The protonation reactions take place at [H+] > 0.36 mol.dm-3. The ligand begins dissociations at pH > 0.5. Two protons are released in the complexes formation reactions(Me2+ + 2HI half-arrow-pointing-left and half-arrow-pointing-right MeL2 + 2H+). The stability constants of the complexes of Calcium, Strontium and Barium have been determined by Yoe-Jone method, Majumder-Chakrabartty method and calculation method. The order of the stability of complexes is as follows: Sr > Ba > Ca. The structure of the complexes have also been studied by infrared spectroscopy, Laser Raman spectroscopy, NMR, and EPR. The results show that these groups of N = N, PO3H2 and OH are active groups in the complex reactions. The structure of the complexes of Strontium, Barium and Calcium with chlorophosphonazo-DBC are represented and the reaction and the complex bonds are discussed in this paper.

ISOTOPIC CHARACTERISTICS AND AGE DATING OF THE PUMICE IN OKINAWA TROUGH

The data on the isotope compositions of rubidium, strontium and oxygen in the pumice of Okinawa Trough are reported for the first time. The ages of the pumice were successfully dated with the method of U-series disequilibrium. Then, the material source, crystallization evolution of magma and activity cycles of volcanos are explored. Isotopic data show that pumice magma was originally from the mantle, but had undergone a full crystallization differentiation and had been contaminated to a fair extent by crust-derived materials before the magma was erupted out of the sea floor. According to the dating results available so far, the earliest volcanic eruption in Okinawa Trough occurred about 70,000 a ago and the latest eruption was about 10,000 a B.P. During this period, there were three volcanic eruption cycles which were respectively corresponding to the middle Late Pleistocene, the late Late Pleistocene and the Early Holocene.

中国北方表沙无机碳储量及次生碳酸盐固碳潜力研究

This paper selected the Taklamakan Desert and the Badain Jaran Desert as the research areas, tested the carbonate content of surface-sand samples of dunes using Eijkelkamp carbonate goniophotometer, and analyzed the spatial-distribution characteristics of carbonate and estimated the carbonate-stock and secondary carbonate-stock in 1m depth of surface sand in the Taklamakan Desert and the Badain Jaran Desert. In addition, the paper test XRD, SEM, TDA, stable carbon isotope and radioactive strontium isotope of lacustrine deposits in the Taklamakan Desert and carbonates, such as kunkar, root canal, lacustrine deposits, sinter and calcrete, in the Badain Jaran Desert. Resting on the achievements by our predecessors, it analyzed the mineral-composition differences of the carbonates, calculated the contents of secondary carbonate and, furthermore, evaluated their potential of sequestration of CO2 in the atmosphere. The overall goal of this study was to increase our understanding of soil carbonate in the context of carbon sequestration in the arid region in China. That is, to advance our understanding about whether or not secondary carbonate in desert is a sink for atmospheric CO2. The following viewpoints were obtained: 1 Carbonate contents of surface-sand samples decend from the south to the north of the Taklamakan Desert. The minimum lies in the south and the maxmum in the mid. Carbonate content of surface-sand of megadunes in the Badain Jaran Desert has low value generally in the dune-crest and the base of slope, and large value in the mid. The average of Carbonate contents of all sorts of collected samples in the same area of the Taklamakan Desert has small diffetences. The average is about 9%. 2 Using carbonate contents as key parameters, calculate the carbon-stock of carbonates in 1m depth of surface sand in the Taklamakan Desert and the Badain Jaran Deser.They are 1.13Pg and 0.19 Pg respectively. There are 0.53Pg and 0.088Pg carbon-stock of secondary-carbonates in 1m depth of surface sand in the Taklamakan Desert and the Badain Jaran Desert. 3 Through testing data from XRD （X-ray diffraction）and TAD ( Thermal Analysis Data), the most significant conclusion derived from is that the main mineral ingredient is calcite in different carbonate substances in arid regions, From the SEM(Scanning electron microscopy ) images, can obtains the information about the micro environment of different carbonate forms in which they can grow. 4 Selected gas by termal cracking and traditional phosphoric acid method, their δ13C show that δ13C is a good parameter to indicate the micro environment in which different secondary carbonate forms. From the δ13C of the same type samples, if the redeposit degree is hard, theδ13C is light, the redeposit degree is weak, the δ13C is heave. and the δ13C of the different type samples, δ13C is mainly controlled by the micro environment in which secondary formed. if the procedure is characterized by redeposit and dissolve of marine facies carbonate, δ13C is heavy, it is characterized by CO2 which produced by plant respiration,δ13C is light. 5 From the δ13C of lacustrine deposit in the different grain size, there exsit certain differences in their micro environment and secondary degree among different grain size in the same grade. 6 The secondary carbonate content of lacustrine deposits in Taklimakan Desert is 47.26%. And those of root canal, sinter, calcrete, kunkar, lacustrine deposit and surface sand in Badain Jaran Desert are 91.74%, 78.46%, 76.26%, 87.87%, 85.37%and 46.49%, respectively. Of different grain size samples, the secondary carbonate contents of coarse fraction (20-63μm), sub-coarse fraction (5-20μm) and fine fraction (<5μm) are 80.10%, 47.2%and 50.07%, respectively. 7 There is no obvious relevance betweenδ13C of secondary carbonate and the content of secondary carbonate,theδ13C of secondary carbonate mainly reflects the parameters of secondary process, the content of secondary carbonate reflects difference of secondary degree.. 8 Silicates potentially supply 3.4 pencent calcium source during forming process of lacustrine deposits in Taklimakan Desert. If calcium source is mainly supplied by goundwater, it can be calculated that about 5.18 %, 6.13%, 5.68%, 5.64 % and 6.82% silicates supply calcium source respectively for root canal, kunkar, lacustrine deposit, calcrete and sinter, during the forming process of different kinds of carbonates in Badain Jaran Desert.

塔里木盆地柯坪-巴楚露头区白云岩成岩作用机理研究

Through field outcrop dolomite observation, laboratory petrography (macroscopy, microscopy, cathodeluminescence and scan electronic microscopy), geochemistry (carbon-oxygen-strontium isotopes and trace elements) and fluid inclusion microthermometry study in Keping-Bachu area of Tarim Basin, it can be inferred that there are existing eight dolomite texture types within four evolution phases in Keping-Bachu area of Tarim Basin. The paragenesis of different dolomite texture types and associated minerals in Keping-Bachu area has been established. The carbon and oxygen isotopes of saddle dolomites and matrix dolomites overlap greatly. The Strontium isotopes results of Keping-Bachu outcrop area show that the strontium isotopes differentiation of the matrix and saddle dolomites is not obvious, the reason of which is that there is thousands of Cambrian-Ordovician dolomite strata below the stratum bearing the saddle dolomite. In the process of the heat flow upward migration, the isotopes of the heat interacts with the host rock, which leads to the similarity betwwen the strontium of the saddle dolomite and matrix dolomite. The strontium isotope of the saddle dolomite is not very radiogenic. the six types samples within four phases in the study area show Eu negatively. Comparing to the other types of samples, the δEu of saddle dolomite is relatively high falling into the range of 0.510-0.874, which shows that the saddle dolomite forms in the hydrothermal setting and is affected by the hydrothermal activity to some extend.The Lan/Ybn of saddle dolomite is high up to 15.726, which means that the HREE is very rich. It belongs to the typical hydrothermal genesis model. The δCe of saddle dolomite is positive anomaly, which is the result of high effect from the land source debris. The homogeneous temperature of the saddle dolomite falls into two ranges 110-120℃ and 125-160℃, after pressure correction, they are 141-152℃，157.5-196℃, the salinity of the saddle dolomite can reach to 20-25%. With the comparing with the burial history, the Th of the saddle dolomite is high than the ambient strata temperature, these data show that the saddle dolomite is of hydrothermal origin. The evolution trend of different dolomite and associated minerals is from matrix dolomite, dolomite cementation, saddle dolomite, quartz to calcite. Alonging with this evolution trend, the temperature of the diagenetic flow initiated from 80-100℃, after rising to 135-160℃, then gradually declined. Finally, a structurally-controlled dolomitization model is established in Keping-Bachu area of Tarim Basin.

河北寿王坟铜矿成矿定年及同位素地球化学特征

Samples from carbonate wall-rocks, skarn, ore of skarn type, later calcite vein, and ore of porphyry type in Shouwangfen copper deposit district were collected. Systematic study was carried out on carbon, oxygen, rubidium, strontium and sulfur isotope compositions of carbonates and sulfides in these samples. The first Isochron dating by the Rb-Sr isotopes in chalcopyrite of ore sub-sample was done as well. The following conclusions were obtained. The age (113.6±4.3Ma), obtained by Rb-Sr isotope isochron dating of chalcopyrite and pyrite from sub-sample of skarn ores, probably represents the true mineralization age of skarn ores. That demonstrates the genetic relationship between granodiorite in Shouwangfen complex and skarn copper ores. On the other hand, the Rb-Sr isochron age (73±15Ma) of chalcopyrite from porphyry ores is a little incredible because of bad synthesizing evaluation. But combined with other age data of igneous rocks, it implies the possibility of hydrothermal mineralization in connection with magma activity during the fourth period of Yanshanian in Hebei Province, even in the whole northern edge of Huabei continental block. Together from structure analysis of sulfide sub-samples, from pretreating preccedure of Rb-Sr isotope isochron and its' valuating, we found out that Rb-Sr isotope isochron of sulfide sub-samples is influenced by the crystal structure of sulfides. That is, sulfide ores with very big crystals are not suitable for sub-sample isochron. Carbon, oxygen, sulfur and strontium compositions, of different minerals in these two kinds of ores, imply that the ore-forming hydrothermal fluids were probably derived from magma deep under the crust. The calcite ~(87)Sr/~(86)Sr ratios from the porphyry are consistent to the initial 87Sr/86Sr ratio of the Rb-Sr isochron of chalcopyrite and pyrite in the skarn ore, indicating that these two kinds of ores have the same source characteristic, although the porphyry deposit was formed probably 40 million years later than the skarn one according to our dating results. Skarn and skarn ores are usually considered as interaction product between carbonate wall-rocks and magmatic fluids, but the carbon of the sedimentary carbonate seems not involved in the skarn ores. Considering the connection of magmatic processes and hydrothermal ore formation in the Shouwangfen district, particularly, the spatial distribution of skarn-type and porphyry-type ores, it is possible that the Shouwangfen ore district corresponds to a hydrothermal ore-forming system, which was promoted by high-intruding magmatic rocks. Systematic stable isotopic research can help to reveal the upper part of this hydrothermal ore-forming system, which mainly related to heated and circulating meteoric water, and the lower part principally related to ascending magmatic fluids. Both skarn and porphyry ore-bodies are formed by up-intruding magmatic fluids (even more deep mantle-derived fluids).

矾山杂岩体成因及其与磷（铁）矿的成矿关系

The Fanshan complex consists of layered potassic ultramafic-syenite intrusions. The Fanshan apatite (-magnetite) deposit occurs in the Fanshan complex, and is an important style of phosphorus deposit in China. The Fanshan complex consists of three (First- to Third-) Phases of intrusion, and then the dikes. The First-Phase Intrusive contains ten typical layered rocks: clinopyroxenite, biotite clinopyroxenite, coarse-grained biotite clinopyroxenite, pegmatitic orthoclase-biotite clinopyroxenite, variegated orthoclase clinopyroxenite, interstitial orthoclase clinopyroxenite, biotite rock, biotite-apatite rock, biotite rock and magnetite-apatite rock. This layered intrusive consists of nine rhythmic units. Each rhythmic unit essentially comprises a pair of layers: clinopyroxenite at the bottom and biotite clinopyroxenite at the top. The apatite (-magnetite) deposit is situated near the top of rhythmic Unit no. 6 of the First-Phase Intrusive. The Second-Phase Intrusive contains three typical rocks: coarse-grained orthoclase clinopyroxenite, . coarse-grained salite syenite and schorlomite-salite syenite. The Third-Phase Intrusive includes pseudo-trachytic salite syenite, porphyritic augite syenite, fine-grained orthoclase clinopyroxenite and fine-grained salite syenite. The origin of the Fanshan complex is always paid attention to it in China. Because most layered igneous intrusion in the world not only have important deposit in it, but also carry many useful information for studying the formation of the intrusion and the evolvement of magma. Two sketch maps were drawn through orebodies along no. 25 cross-cut on 425 mL and no. 1 cross-cut on 491 mL in the Fanshan mine. Through this mapping, a small-scaled rhythmic layering (called sub-rhythmic layering in the present study) was newly found at the top of the rhythmic Unit no. 6. The concept of sub-rhythmic layering is defined in this article. The sub-rhythmic layering is recognized throughout this apatite-rich part, except for magnetite-apatite rock. Presence of the layered magnetite-apatite rock is one of the characteristics of the Fanshan apatite (-magnetite) deposit. Thus, from this layer downwards six units of sub-rhythmic layering are recognized in the present study. Each unit consists of biotite clinopyroxenite (or biotite rock and biotite-apatite rock) layer at the bottom and apatite rock layer at the top. To study this feature in detail is an important work for understanding the origin of the Fanshan complex and apatite (-magnetite) deposit. The origin of the Fanshan complex and the relation of the formation of the apatite(-magnetite)deposit will be interpreted by the study of sub-rhythmic layering on the basis of previous research works. The magma formed the Fanshan complex was rich in K2O, early crystallized pyroxene, and after this phase more biotite crystallized, but no amphibole appeared. This indicated that the activity of H2O in the magma was low. Major element compositions of biotite and clinopyroxene (on thin sections) in the sub-rhythmic layering were analyzed using electron microprobe analyzer. The analytical results indicate Mg/(Mg+Fe*+Mn) atomic ratios (Fe*, total iron) of these two minerals rhythmically changed in sub-rhythmic layering. The trends of Mg/(Mg+Fe*+Mn) atomic ratio (Fe*, total iron) of biotite and clinopyroxene indicate that the magma evolved markedly from relatively magnesian bottom layer to less magnesian top layer in each sub-rhythmic unit. A general trend through the sub-rhythmic layering sequence is both minerals becoming relatively magnesian upwards. The formation temperatures for sub-rhythmic layering yield values between 600 and 800 ℃, were calculated using the ratio of Mg/(Mg+Fe+Mn) in the salite and biotite assemblage. The equilibrium pressures in the rhythmic layers calculated using the contents of Al in the salite were plotted in the section map, shown a concave curve. This indicates that the magma formed the First-Phase Intrusive crystallized by two vis-a-vis ways, from its bottom and top to its centre, and the magnetite-apatite rock was crytallized in the latest stage. The values of equilibrium pressures in the sub-rhythmic layering were 3.6-6.8(xlO8) Pa with calculated using the contents of Al in the salite. The characteristics of geochemistry in various intrusive rocks and the rocks or apatite of sub-rhythmic layers indicated that the Fanshan complex formed by the comagmatic crystallization. The contents of immiscible elements and REEs of apatite rock at the top of one sub-rhythmic unit are more than biotite clinopyroxenite at the bottom. The contents of immiscible elements and REEs of apatite of biotite clinopyroxenite at the bottom of one sub-rhythmic unit are higher than apatite rock at the top. The curves of rocks (or apatite) in the upper sub-rhythmic units are between two curves of the below sub-rhythmic unit in the primitive mantle-normalized trace element abundance spider diagram and the primitive mantle-normalized REE pattern. The trend for the contents of immiscible elements and REEs inclines to the same contents from the bottom to the top in sub-rhythmic layering. These characteristics of geochemistry of rocks or apatites from sub-rhythmic layering indicate that the latter sub-rhythmic unit was produced by the residual magma after crystallization of the previous sub-rhythmic unit. The characteristics of petrology, petrochemistry, geochemistry in the Fanshan complex and sub-rhythmic layers and the trends of Mg/(Mg+Fe+Mn) atomic ratio of biotite and clinopyroxene in sub-rhytmic layering rejected the hypotheses, such as magma immiscibility, ravitational settling and multiple and pulse supplement of magma. The hypothesis of differentiation by crystallization lacks of evidences of field and excludes by this study. On the base of the trends of formation temperatures and pressures, the characteristics of petrology, petrochemistry, geochemistry for the Fanshan complex and the characteristics of geochemistry for the rocks (or apatites), the trends of Mg/(Mg+Fe+Mn) atomic ratio of biotite and clinopyroxene in sub-rhytmic layering, and the data of oxygen, hydrogen, strontium and neodymium isotopes, this study suggests that the magma formed the Fanshan complex was formed by low degree partial melting of mantle at a low activity of H2O, and went through the differentiation at the depth of mantle, then multiply intruded and crystallized. The rhythmic layers of the First-Phase Intrusive formed by the magma fractional crystallized in two vis-a-vis ways, from the bottom and top to the centre in-situ fractional crystallization. The apatite (-magnetite) deposit of the Fanshan complex occurs in sub-rhythmic layering sequence. The the origin of the sub-rhythmic layering is substantially the origin of the Fanshan apatite (-magnetite) deposit. The magma formed the rhythmic layers of First-Phase Intrusive was rich in H2O, F and P at the later stage of its in-situ fractional crystallization. The Fanshan apatite (-magnetite) deposit was formed by this residual magma in-situ fractional crystallization. The magnetite-apatite rock was crystallized by two vis-a-vis ways at the latest stage in-situ fractional crystallization in the rhythmic layers. The result was light apatite layer below heavy the magnetite-apatite layer, formed an "inversion" phenomenon.

喀斯特地区森林生态系统物质循环的锶同位素地球化学研究

钙是地壳中最丰富的碱土金属元素，同时也是所有植物生长所需要的常量营养元素。越来越多的证据表明Ca是影响森林生态系统结构和功能的重要因素。贵州地处典型喀斯特地区，也是我国酸雨重灾区之一。酸沉降可以导致土壤中盐基离子的流失并释放出具有植物毒性的元素，对森林生态系统造成破坏。在酸化土壤上，Ca的流失可以直接或间接地影响森林的生产力。在受到酸沉降影响的森林生态系统，Ca、Mg、K等植物生长所必须的常量营养元素将从土壤可交换态离子库中淋失。大气输入与岩石风化是森林生态系统K、Ca、Mg等碱基离子的主要来源，了解二者的输入比率及转化是研究森林流域内物质循环过程的关键。为了评估森林健康状况和酸沉降对森林生态系统的影响，识别并区分植物营养物质的不同来源是非常有必要的。 喀斯特地区森林生态系统是物质、能量交换复杂且快速的开放系统。本论文应用Sr同位素示踪方法研究了酸沉降对贵州省喀斯特地区森林小流域营养离子循环的影响。选择了一处典型的森林小流域，把“岩石－土壤－地表水－大气沉降－植物”作为一个完整的系统考虑，系统采集了大气降水、穿冠水、地表水、植被、土壤、岩石样品。利用化学质量平衡、锶同位素地球化学等研究手段，探讨了喀斯特森林小流域水循环过程中营养元素和锶同位素组成的时空变化，评判了酸沉降对土壤－植被系统中营养元素与锶同位素组成的影响，定量计算了大气沉降与土壤风化分别对森林植被营养物质来源的贡献率，并进行了微生物对矿物差异风化作用锶同位素示踪的探索性研究，揭示了喀斯特背景下森林生态系统营养物质来源、分布以及迁移转化规律，为喀斯特地区森林生态环境质量评价及其环境保护提供科学依据。主要结论如下： 1．龙里森林小流域降雨的pH显示改区属于受酸雨危害地区。从大气降水到地表水的转化过程中，水溶液中主要离子的浓度发生了较大的变化。在酸雨影响下，雨水对林冠主要表现为营养阳离子的淋失作用，阴离子除NO3-被叶片吸收外总体上也是表现为淋失作用。龙里森林小流域水溶液的锶同位素比值组成总体上受灰岩风化端元控制，水体的87Sr/86Sr的比值变化范围为0.70716～0.71051。大气降水、穿冠水、地表水等不同类型水溶液的锶同位素比值组成变化反映了水循环过程中水溶液与周围环境进行离子交换。 2．土壤中可交换态离子、碳酸盐岩结合态离子和全样的锶同位素组成之间在同一剖面存在较大的变化，且在土壤剖面垂向上也存在着较大的变化。黄壤剖面中不同赋存形式离子的锶同位素组成之间的变化较之石灰土剖面更为明显。可交换态离子的锶同位素比值变化特征可以很好地说明雨水对土壤的影响程度。黄壤剖面土壤可交换态离子的锶同位素比值在土壤剖面形成的垂向分布梯度，反映了雨水对土壤的影响可以达到130 cm深度。 3．喀斯特地区黄壤上生长的植物具有高钙含量的特征，营养元素含量具Ca > K > Mg特点。研究区植物Ca、K、Sr的平均含量均高出报道的陆生植物的平均含量, 但比贵州地区同样以灰岩为母质发育而来的石灰土上生长的植物低。石灰土上植物体内（包括皮、叶、根、茎）的Ca含量比黄壤上植物体内的高，而Sr、Ba、Mn含量则比黄壤上植物体内的低；阔叶树的营养元素含量一般大于针叶树的。 4．不同植物种所吸收的营养元素来源存在差异。基于锶同位素组成的端元模式计算结果表明，苔藓和石松吸收的营养阳离子主要来自大气沉降，苔藓可以达到 88.66%，石松则为77.28%。除了苔藓、石松外，喀斯特地区黄壤上植物生长所需的58.88%～85.64%的Ca、Mg来自土壤风化所产生的可交换态阳离子，大气输入部分所占份额相对较小。 5．土壤中可交换态离子的锶同位素比值是植物体的锶同位素组成的主要影响因素。植物叶片、韧皮、根等不同器官的87Sr/86Sr比值之间存在较大变化，并且树根的87Sr/86Sr比值随着土壤深度加大在垂向上产生变化，反映了植物器官对不同来源营养元素的利用效率存在差异。同样生长在龙里石灰土样地上的马尾松和光皮桦在树根的锶同位素垂向变化上有较大差别，这可能与其植物生理生态特性有关。老叶与新叶之间87Sr/86Sr比值则没有变化。 6．利用Sr同位素示踪方法能较好地区分混合体系中Ca2+等离子由不同矿物风化所释放的比例，进而定量分析微生物对矿物的差异风化作用。在磷灰石和方解石组成的混合体系中，随着微生物培养时间的延长，培养基上清液的87Sr/86Sr比值随时间变化，这反映出方解石与磷灰石两种矿物的微生物风化释放离子对培养液中Ca2+来源的相对贡献率发生改变。基于锶同位素组成的端元模式计算结果表明，黑曲霉组培养液中的Ca2+先由方解石风化所贡献，随后黑曲霉对方解石的风化作用减弱，此时，溶液中Ca2+主要来自磷灰石的风化；而青霉组培养液中的Ca2+先来自磷灰石的风化，随后来自方解石的风化。

中国南北方泥盆纪腕足化石碳、氧、锶同位素研究

海相碳酸盐岩C、O、Sr 同位素研究是地球化学重要的示踪手段之一。它可以为认识地质历史时期的气候变化，海水原始碳、氧、锶同位素组成，陆地和海洋生物盛衰的长期变化特征，以及碳、氧等元素的外生循环等一些重大的基础学科问题提供重要的依据。研究表明：腕足化石因具有较强抵抗成岩后生作用能力、分布广泛、便于操作等原因被认为是较为理想的研究样品之一。 本论文对来自中国南、北方泥盆纪不同沉积单元腕足化石碳、氧、锶同位素组成进行测试，探讨中国南、北方不同沉积单元腕足化石碳、氧、锶同位素差异。从地球化学角度对我国泥盆纪海平面变化，海洋生物盛衰、陆地风化强度以及构造运动研究进行诠释。 中国泥盆系沉积类型齐全，从南到北，分布着不同构造单元条件下沉积而成的地层。华南泥盆系属地台型稳定沉积类型，四川龙门山地区泥盆系形成于冒地槽构造单元中，而中国北方泥盆系为优地槽活动构造单元的产物。三类构造单元的地壳活动和火山活动不同，生活在其中的腕足壳体碳、氧、锶同位素组成是否存在差异？不同构造单元的海平面变化、海洋生物盛衰以及陆地风化强度是否不同。 研究中通过上述不同沉积单元腕足化石碳、氧、锶同位素组成详细研究，得出以下几点认识： 1) 在腕足化石保存鉴定过程中：微体结构实验显示南、北方剖面腕足化石壳体结构保存完整，有着明显的纤维层和棱柱层结构，但北方剖面腕足化石微裂隙较多，有着不少后期物质充填。在阴极灯照射下，南方剖面腕足化石基本不发光，仅因少量裂隙中后期物质充填有着微弱发光现象存在。北方剖面腕足化石基本上都有着轻微发光现象，尤其内蒙古地区腕足化石。微量元素Fe、Mn、Sr 含量及其Mn/Sr 值表明南、北方剖面腕足化石绝大多数符合腕足保存完好的标准。表明：南方剖面腕足化石保存完好，可以用于的碳、氧、锶同位素组成研究。北方剖面腕足化石保存程度较差，其同位素信息可能遭受成岩蚀变作用的影响，特别是容易遭受蚀变影响的氧同位素组成。 2) 成岩后生作用总是导致碳酸盐岩全岩样品中碳、氧、锶同位素组成发生变化，无法保存原始的同位素信息。腕足化石同碳酸盐岩全岩碳、氧、锶同位素对比表明：碳酸盐岩全岩样品中碳、氧同位素组成都低于腕足化石样品中同位素组成，锶同位素组成正好相反，但在不涉及定量化研究的前提下，碳、锶同位素基本上可以代表着地质历史时期碳、锶同位素变化趋势。也即是说可以利用碳酸盐岩全岩样品进行碳、锶同位素演化趋势研究。至于碳酸盐岩全岩样品中氧同位素组成，低于腕足化石氧同位素组成达 -2‰～-3‰。在目前常用于氧同位素古温度的研究中差异太大。因此，建议不要利用碳酸盐岩全岩样品中氧同位素组成进行古温度研究。 3) 碳同位素组成变化可以指示有机碳的埋藏情况。中国南、北方剖面腕足化石碳同位素研究表明：腕足化石中碳同位素组成基本上在 -2‰ ～ 4‰之间变化，北方剖面较低，南方剖面较高。其碳同位素Locfit 演化对比显示：北方剖面碳同位素演化同华南以及四川龙门山剖面中碳同位素演化有着许多相似之处，表明北方海域有机碳埋藏情况同南方海域有机碳埋藏情形基本一致。分析表明：四川龙门山以及华南剖面泥盆纪时期有着三次有机碳高速埋藏时期，可能受海平面变化以及与之有关的生物繁盛状况共同控制。至于北方剖面碳同位素组成相对较低，一方面可能由于腕足化石保存方面的原因，在成岩蚀变作用影响下北方剖面腕足碳同位素组成较低。另一方面，北方地区较多的火山活动，释放大量含有较多12C 的CO2，融入海水发生同位素交换，导致北方地区碳同位素组成较低。 4) 由于北方剖面存在遭受成岩蚀变作用影响的可能，北方剖面腕足化石壳体氧同位素平均组成(-11.75‰ ~ -21.13‰)明显低于四川龙门山剖面(-5.14‰ ~-7.20‰)、华南剖面(-4.35‰ ~ -10.31‰)氧同位素平均组成，无法对水岩反应控制海洋中氧同位素组成给出肯定的答案。但腕足化石保存完好的四川龙门山剖面和华南剖面氧同位素组成(氧同位素素组成埃姆斯阶为-7.20‰、-7.58‰；吉维特阶-5.62‰、-4.60‰；氟拉斯阶-5.18‰、-4.35‰)显示：优地槽沉积单元的龙门山海域同稳定地台沉积单元的华南海域氧同位素一致，甚至较低，表明水岩反应根本无法控制海洋中氧同位素组成。 5) 四川龙门山剖面下泥盆统埃姆斯阶氧同位素组成为 -9.9‰～-4.5‰，明显低于世界上其他地区同时期腕足化石的氧同位素组成，其差异达 -3‰~-4‰。微量元素Fe、Mn 的演化趋势以及氧同位素演化趋势显示：龙门山海域在埃姆斯阶时期同广阔海域之间海水交流不畅通，其氧同位素组成受淡水河流注入的影响。根据氧同位素古温度计估算(假定古海水δ18O 值为 -3‰SMOW)，姆斯阶时期温度高达52℃，远远超过生物所能生存的极限，印证龙门山海域埃姆斯阶氧同位素组成受淡水河流注入的影响。艾菲尔阶～氟拉斯阶，龙门山海域的温度为21℃ ～33℃，表明龙门山海域为典型的低纬地区热带气候。 6) 早泥盆纪时期，锶同位素比值较高，显示风化作用较为强烈；可能是由于加里东造山作用的影响，大量陆地的暴露，促进风化作用的进行。其后，锶同位素组成逐渐降低指示风化作用变弱。锶同位素降低可能由于海底扩展运动造成幔源锶的增加，同时引起海平面上升，引起陆地风化面积的减少，导致风化作用的减弱。幔源锶增加和陆源锶的减少，造成锶同位素比值的不断下降。早泥盆世晚期－中泥盆世，锶同位素组成显示风化作用(强度较低)和构造运动稳定。可能原因为在海平面较高时海侵－海退幅度较小，幔源锶和陆源锶之间达到均衡。中泥盆世后期，锶同位素组成显示：风化作用程度较强。可能由于该时期温度的缓慢上升，导致风化作用加强，陆源锶输入增多引起的。 7) 不同沉积单元腕足化石碳、氧、锶同位素对比表明：局部的区域环境对碳、氧、锶同位素有影响。在考虑利用不同剖面进行地质历史时期某时段碳、氧、锶同位素数据叠加构建完整同位素演化曲线时；对于碳同位素，相同沉积单元条件下，辨别出长时间变化和局部影响时可以应用于同位素演化曲线的构建。而不同沉积单元的碳同位素组成存在差异，不能应用于碳同位素曲线的构建。不同沉积单元氧同位素组成存在较大差异，相同沉积单元的氧同位素组成同样也存在较大差别，表明局部环境对氧同位素组成影响较大，氧同位素曲线的构建最好避免多个剖面的叠加。锶同位素比值，不同沉积单元在长期演化趋势上基本一致，在排除局部环境因素的影响下可以进行多剖面锶同位素演化曲线的构建。

赣江流域水化学特征与流域风化过程——主成分及锶同位素地球化学研究

对河流地球化学特征的研究可以获得有关流域化学风化以及化学元素在地球表生系统生物地球化学循环的相关信息。同时，流域风化作用是全球长期碳旋回及与其有关的环境效应的一个重要组成部分。我国学者对大流域的碳酸盐岩地区进行了大量研究，但硅酸盐地区的研究相对薄弱，研究指出：中国河流水的离子组成主要受碳酸盐风化作用和蒸发岩溶蚀作用的影响，受铝硅酸盐风化作用的影响不如前两者明显。硅酸盐岩的风化产物在一定程度上控制着地表水系的地球化学组成，因而对硅酸盐岩区河流的地球化学组成变化的研究，有助于我们了解硅酸盐岩地区的化学风化作用与水文地球化学特征的关系，以及控制河流水体地球化学组成变化的多种因素。赣江是长江的主要支流，在江西省国民经济、生态环境保护和社会生活中占有重要的地位。尤为重要的是，赣江流域广泛分布有硅酸岩岩石和土壤，是世界上硅酸岩连片分布的典型地区之一。由赣江水体和悬浮物携带输送的各类物质组分经鄱阳湖输入长江是全球元素地球化学循环的重要组成部分，对全球环境变化研究有重要意义。 本论文利用赣江流域物理化学参数、化学质量平衡和同位素地球化学研究手段，重点讨论赣江流域的水化学特征、主要离子来源，并探讨主要的化学风化反应。定量计算了流域化学风化侵蚀速率及其对大气CO2消耗的影响，探讨了河流水化学特征与人为活动、气候、地形、岩性等因素之间的关系。得出如下主要结论和几点新认识。 赣江流域河流受控于中亚热带湿润季风气候条件下，碳酸盐硅酸盐化学风化和人为活动的共同影响，以快速的碳酸盐和典型硅酸盐的化学风化共同侵蚀作用区别于其他地区河流。枯水期和丰水期样品中，阳离子中Na+和Ca+含量最高，其次是Mg2+，K+含量最低；阴离子中，Cl-，HCO3-占主导地位，SO42-次之，NO3-含量最低；溶解性硅的含量变化范围不大。赣江流域河水的化学组成反映了硅酸盐岩化学风化作用对河水化学组成控制的典型特征。 受赣江流域气候、岩性、地形和人为活动的影响，枯水期丰水期离子成分主要来源于岩石/土壤的化学风化。碳酸盐岩矿物风化与硅酸盐岩矿物相比是普遍而快速的，所以赣江流域风化很大程度上会受碳酸盐所支配。此外，人为输入影响与赣江流域发达的农业、工业生产产生污染相一致。 赣江流域HCO3-与Ca2+、HCO3-与Mg2+、SO42-与Mg2+、Na+与Cl-均存在明显的相关关系。Na+与SO42-、HCO3-与Si、Na+与Si、K+与Si不存在相关性或相关性不明显。赣江流域样品Si/(Na*+K)比值范围低，表明风化作用在表生环境中进行，风化作用中主要是富含阳离子的次生矿物。Si浓度受生物影响很小，主要是岩性的作用。 除了岩石风化溶解作用，赣江流域盆地区域降水量将直接影响地表径流和河流流量。河流流量对各主要离子浓度的影响顺序为HCO3->Ca2+>Mg2+>SO42- >Na+>Cl-，起到稀释作用。所以赣江流域河水特征受岩性和气候条件的共同作用。 赣江流域高的锶同位素比值（87Sr/86Sr）表明了赣江流域Sr来源的硅酸岩风化典型特征，丰水期河流溶解态Sr浓度有所下降。锶同位素为大气降水和岩石风化的混合型，并且辨别出两个碳酸盐硅酸盐是最主要的岩石风化溶解端元组分。 利用SPSS统计软件，对9个离子组分作为变量进行主成分分析（PCA）和因子分析，解析出主要影响因素。分析统计结果表明两类岩石和人为输入对河水溶解质的贡献率分别是：碳酸盐最大，其次是硅酸盐，人为活动输入最小。并定量的计算出碳酸盐、硅酸盐、大气CO2和人类活动对于赣江溶质组成的相对贡献率。根据径流量和流域面积，计算得到每年赣江流域岩石风化作用的大气CO2消耗分别为枯水期520.2×103mol/km2和丰水期383.4×103mol/km2，较强烈的碳酸盐风化溶解和明显的硅酸盐风化特征导致了赣江流域岩石风化作用的CO2消耗率高于世界平均水平。扣除大气CO2和人类活动输入的贡献后，估算得到赣江流域的年均化学风化率为30.3t/km2•a，在影响河流化学风化的众多因素中，地质和气候因素起着主导作用。赣江流域对于全球的大气CO2源汇效应是明显的汇项。