Triplophysa rosa sp nov.: a new blind loach from China

A new blind loach of Triplophysa Rendahl 1933 was collected from a subterranean pool in a cave at Wulong County, Chongqing City, China, in November 2002. The new species, named Triplophysa rosa sp. nov., can be distinguished from its congeners by the following unique characters: eyes vestigial; 9 branched dorsal-fin rays; 12 branched pectoral-fin rays; 7 branched pelvic-fin rays; 6 branched anal-fin rays; 7 + 7 branched caudal-fin rays; distal margin of dorsal-fin concave; tip of pelvic-fin surpasses vertical level of anus; caudal-fin deeply forked; whole body scaleless and colourless. (c) 2005 The Fisheries Society of the British Isles.

The Hypogean fishes of China

China has 92 described species of hypogean (cave and artesian) fishes. That is nearly one third of all the described hypogean fish species (299), more than any other country. Of all Chinese hypogean fishes 56 species show troglomorphisms, i.e., adaptation

Distinct Evolutionary Patterns Between Two Duplicated Color Vision Genes Within Cyprinid Fishes

We investigated the molecular evolution of duplicated color vision genes (LWS-1 and SWS2) within cyprinid fish, focusing on the most cavefish-rich genus-Sinocyclocheilus. Maximum likelihood-based codon substitution approaches were used to analyze the evolution of vision genes. We found that the duplicated color vision genes had unequal evolutionary rates, which may lead to a related function divergence. Divergence of LWS-1 was strongly influenced by positive selection causing an accelerated rate of substitution in the proportion of pocket-forming residues. The SWS2 pigment experienced divergent selection between lineages, and no positively selected site was found. A duplicate copy of LWS-1 of some cyprinine species had become a pseudogene, but all SWS2 sequences remained intact in the regions examined in the cyprinid fishes examined in this study. The pseudogenization events did not occur randomly in the two copies of LWS-1 within Sinocyclocheilus species. Some cave species of Sinocyclocheilus with numerous morphological specializations that seem to be highly adapted for caves, retain both intact copies of color vision genes in their genome. We found some novel amino acid substitutions at key sites, which might represent interesting target sites for future mutagenesis experiments. Our data add to the increasing evidence that duplicate genes experience lower selective constraints and in some cases positive selection following gene duplication. Some of these observations are unexpected and may provide insights into the effect of caves on the evolution of color vision genes in fishes.

Relaxed purifying selection of rhodopsin gene within a Chinese endemic cavefish genus Sinocyclocheilus (Pisces: Cypriniformes)

The cyprinid fish genus Sinocyclocheilus, as the most cavefish rich genus, includes many species showing striking adaptation to caves and convergent reduction or even loss of eyes and pigmentation. RH1 is responsible for dim vision. In order to explore the evolution of RH1 gene in this genus, we sequenced the complete gene from 28 individuals of 16 representative species of Sinocyclocheilus, with cave and surface species included. Phylogenetic analyses supported the monophyly of Sinocyclocheilus and polyphyly of the cave species. Codon models implemented in PAML were used to infer the evolution of RH1. We found that Sinocyclocheilus had a significantly higher evolutionary rate for amino acids than other cyprinid fishes compared, which might be the result of relaxation of purifying selection and could be ascribed to cave habit of this genus. In contrast to previous hypotheses, both cave and surface lineages exhibited a similar rate of molecular evolution, so the RH1 of cave species may still be functional, although these species were highly adapted to cave environment. Two amino acid substitutions (D83G and E122V) that were not reported before were found, which may be useful for site-directed mutagenesis in the future.

Bayesian mixed models and divergence time estimation of Chinese cavefishes (Cyprinidae : Sinocyclocheilus)

The genus Sinocyclocheilus is distributed in Yun-Gui Plateau and its surrounding region only, within more than 10 cave species showing different degrees of degeneration of eyes and pigmentation with wonderful adaptations. To present, published morphological and molecular phylogenetic hypotheses of Sinocyclocheilus from prior works are very different and the relationships within the genus are still far from clear. We obtained the sequences of cytochrome b (cyt b) and NADH dehydrogenase subunit 4 (ND4) of 34 species within Sinocyclocheilus, which represent the most dense taxon sampling to date. We performed Bayesian mixed models analyses with this data set. Under this phylogenetic framework, we estimated the divergence times of recovered clades using different methods under relaxed molecular clock. Our phyloegentic results supported the monophyly of Sinocyclocheilus and showed that this genus could be subdivided into 6 major clades. In addition, an earlier finding demonstrating the polyphyletic of cave species and the most basal position of S. jii was corroborated. Relaxed divergence-time estimation suggested that Sinocyclocheilus originated at the late Miocene, about 11 million years ago (Ma), which is older than what have been assumed.

黄土丘陵沟壑区山坡道路防蚀措施初步研究

山坡道路连接农田、果园 ,对山区经济发展有重要作用。黄土高原山坡道路存在严重的水土流失 ,侵蚀方式主要有沟蚀、泻溜、崩塌、陷穴、悬沟侵蚀与滑坡等。山坡道路网应按照小流域综合治理规划合理布置 ,其主要防护措施 :①修筑梯田 ,防止坡面径流冲刷道路 ;②将路面整修成拱形以分散径流 ;③在道路内侧修蓄水窑窖 ,拦蓄径流 ;④路面及边坡栽植草灌 ,防止雨水冲刷

碳酸盐岩缝洞型储层地球物理响应特征及预测方法研究

Proven by the petroleum exploration activities, the karsts-fissure reservoir in carbonate rocks is significant to find out the large scale oil & gas field. They are made up of the four reservoir types: karsts-cave, karsts-crack, crack-cave and fracture-pore-cave. Each reservoir space and each reservoir bed has different features of reservoir heterogeneity and small scale of pore-crack-cave. The fracture-cave reservoir in carbonate rocks is characteristic by multi-types and long oiliness well. The reservoir shape is controlled by the irregular pore-crack-cave. The development level of fracture and karst-cave is the key element of hydrocarbon enriching, high productivity and stable production. However, most of Carbonate formation are buried deeply and the signal-ration-noise of seismic reflection are very low. It is reason why the fracture-cave reservoir are difficult to be predicted effectively. In terms of surveyed and studied lots of the former research outcome, The author applied the methods of synthetical reservoir geophysical prediction from two ways including macrosopic and microcomic technics in terms of the reservoir-cap condition, geophysics and geology feature and difficulty of prediction in carbonate rocks. It is guiden by the new ideas of stratigraphy, sedimentology, sedimentography, reservoir geology and karst geology. The geophysics technology is key technics. In aspects of macroscopic studies, starting off the three efficiencies of controlling the reservoir distribution including sedimental facies, karst and fracture, by means of comprehensive utilization of geology, geophysics, boring well and well log, the study of reservoir features and karst inside story are developed in terms of data of individual well and multiple well. Through establishing the carbonate deposition model, karstic model and fracture model, the macro-distribution laws of carbonatite are carried out by the study of coherence analysis, seismic reflection feature analysis and palaeotectonics analysis. In aspects of microcosmic studies, starting off analysis in reservoir geophysical response feature of fracture and karst-cave model according to guidance of the macroscopic geological model in carbonate reservoir, the methods of the carbonate reservoir prediction are developed by comprehensively utilization of seismic multi-attribution intersection analysis, seismic inversion restricted by log, seismic discontinuity analysis, seimic spectrum attenuation gradient, moniliform reflection feature analysis and multiparameter karst reservoir appraisement.Through application of carbonate reservoir synthetical geophysics prediction, the author r successfully develops the beneficial reservoir distribution province in Ordovician of Katake block 1in middle Tarim basin. The fracture-cave reservoir distributions are delineated. The prospect direction and favorable aims are demonstrated. There are a set of carbonate reservoir prediction methods in middle Tarim basin. It is the favorable basic technique in predicting reservoir of the Ordovician carbonate in middle Tarim. Proven by exploration drilling, the favorable region of moniliform reflection fracture and pore-cave and cave-fracture in lower-middle Ordovician are coincidence with the region of hydrocarbon show. It’s indicated that the reservoir prediction methods described in the study of Ordovician carbonate formation are feasible practicably.

束鹿凹陷泥灰岩储层综合评价与加砂压裂技术研究与应用

Luo Ning ( Mineralogy, Petrology, Deposit Mineralogy) Directed by Fu Liyun With the increase of the level of exploration and development, North China field, as one of the maturing fields in the east, has gradually turned their prospecting targets to frontiers such as deep zones, lithologic hydrocarbon reservoirs, low permeable layers, special lithostromes, etc, which propose new challenges to mating technique of exploration engineering. In it, the special lithostrome of clay carbonate in Shu-Lu cave in Middle Flank exploration area locates in Es_3 generating rock. The area distribution is large, formation thickness is over 100 meters, the oil accumulation condition is excellent, prognostic reserves is over 80,000,000 tons, but how to effectively stimulate the special low permeable and fractured reservoir has become the bottle neck problem of stimulation and stable yields. In this thesis, through comprehensive evaluation and analysis of lithology, lithomechanics, hydrocarbon reservoir characteristics, the characteristics of fluid flow through porous medium and the stimulation measures in the past, we acquire new cognition of clay carbonate reservoirs, in addition, the research and application of first hydraulic fracturing has gained positive effect and formed commensurable comprehensive reservoir evaluation technique and mating engineering technique of hydraulic fracturing. The main cognitions and achievements are as follows: 1.Study of geological information such as lithololy analysis and nuclear magnetic logging, etc, indicates that clay carbonate formation of Shu-Lu cave is anisotropic, low permeable with high shale content, whose accumulation space gives priority to microcracks. 2.The analysis of lithomechanics of clay carbonate indicates that the hardness is moderate, Young’s modulus is between that of sandstone and limestone, clay carbonate presents plastic property and its breakdown pressure is high because of the deep buried depth. 3.The analysis of the drillstem test curves indicates that the flow and build-up pressure curve of clay carbonate of Shu-Lu cave mainly has three types: formation contamination block-up type, low permeable type, formation energy accumulation slowness type; the reservoir characteristics presents double porosity media, radial compounding, uniform flow vertical fracture, isotropy, moniliform reservoir type. The target well Jingu 3 belongs to moniliform reservoir type. 4.Through recognition and re-evaluation of the treatment effect and technologic limitations of acidizing, acid fracturing and gelled acidizing in the past, based on the sufficient survey and study of hydraulic fracturing home and abroad, combined with comprehensive formation study of target well, we launched the study of the optimization of hydraulic fracturing technique, forming the principal clue and commensurable mating technology aimed at clay carbonate formation, whose targets are preventing leak off, preventing sand bridge, preventing embedment, controlling fracture height, forming long fracture. 5. Recognition of stimulation effect evaluation.

北京石花洞滴水沉积的季节变化及影响因素

Because of the high resolution, stalagmite laminae can play an important role in the paleoclimate reconstructions. However, few investigations for the formation mechanisms of stalagmite lamilae have been done. Based on two-year observation on calcite growth rate at the drip sites, three-year monitoring of hydrodynamics, physics and chemistry of drip waters at different drip sites and the surrounding environments inside and outside the Beijing Shihua Cave, the seasonal variations of calcite growth rate are revealed and the results can be concluded as follows: 1. The drip waters inside the Cave are mostly sourced from the summer rain, and its minimal response-time to the atmospheric precipitation is less than one day. There are three types of response relationships between the precipitation and the drip rate variations: rapid response type, time-lag response type and stable response type. For rapid response type, the drip discharge is recharged through the flow routes along intensive fractures and interconnectivities; for time-lag response type, the drip discharge is recharged by double-porosity system composed of a high conductivity, low storage capability conduit network and a low-conductivity high-storage capability rock matrix under variable boundary conditions; for stable response type, the drip discharge is mainly recharged by seepage flow and base flow. 2. The observation shows that, inside the Cave, the growth rate of calcite is generally lower in rainy seasons and higher in dry seasons. During the rainy seasons, the drip water is characterized by a lower pH value, higher [Ca2+], [Mg2+], [SO42-] and electrical conductivity (EC) values. According to the calculations of saturation index of calcite (SIc), pCO2 of the drip water, as well as the synthetical analysis of other possible factors, the calcite growth rate is found to be principally influenced by the drip water saturation index of calcite (SIc). And the drip rate and pCO2 in the drip water and in the cave air play the secondly important roles in this process. The recharge mode of heavy rainfall events in the rainy seasons should probably be the main driving force that controls the physicochemical properties and calcite sediment of the drip waters. The abrupt decrease of sedimentary rate and the sharp peak of DOC in drip water in the rainy season probably forms the thin opaque (luminescent under ultraviolet radiation) layers observed in the stalagmites, whereas the relatively higher sedimentary rate in the dry seasons may be responsible for the thicker bright layers. The investigation elucidated here preliminarily reveals the formation mechanism of the stalagmite laminae in Beijing Shihua Cave.

东北四海龙湾玛珥湖啊1500年来长链烯酮不饱和度温标与古水温重建

The alkenone unsaturation paleothermometer is an important proxy to reconstruct water temperature, and is widely applied to reconstructing sea surface temperature in most oceanographic settings. Recent research indicates that long chain alkenone is preserved in lacustrine sediments, and the alkenone unsaturation has good relationship with mean annual temperature in studied lakes. Thus, the alkenone unsaturation could be used as a temperature proxy to reconstruct temperature in limnic systems. In this study, we analyzed long chain alkenone from the varved sediments in Lake Sihailongwan, northeastern China. Based on the counting varves, we established time scale during the past 1500 years. The distribution pattern in the sediment is similar with the previous study in lacustrine environment. The ratio of C37:4 methyl ketone to the sum of C37 alkenones is high. Based on the published temperature- alkenone unsaturation equation, we reconstructed the mean air temperature and July water temperature during the past 1500 years. Three major cold periods are in AD560-950, AD 1540-1600 and AD1800-1920. Three major warm periods are AD450-550, AD 950-1400 and AD 1600-1800. The Medieval Warm Period was a significant warm periods. However, the traditional “Little Ice Age” was not a persistent cold period, and interrupted by relative longer warm period. The temperature variations in this study show a general similar pattern with the summer temperature reconstruction from Shihua Cave and the winter temperature from historical documents. The temperature variations from long chain alknone record show a good agreement with solar activity (10Be data from ice core and sunspot number from tree rings). It may suggest that solar activity is most important forcing in the studied area.

塔里木盆地奥陶系不整合面岩溶作用特征与油气储层研究

Based on the principle and methods of carbonate sedimentology and reservoir geology, and guided by the theories of carbonate reservoir geology, the palaeokarst of Ordovician carbonate rocks in Tarim Basin has been comprehensively studied with multiple methods from different branches of geology. It is indicated that the features and distribution of palaeokarstification have developed in Ordovician carbonates. The controlling of karstification to Ordovician carbonate reservoirs has been discussed. Regional distribution of carbonate reservoirs controlled by karstification has been predicted within this basin. The main consents and conclusions of the this dissertation is as follows: Nine key indicators to the recognition of palaeokarst are proposed in terms of careful observation upon the well cores, lithological and geochemical analyses, and drilling and logging responses to the karst caves and fractures. The time and environment of cave filling are documented from careful research of lithofacies, mineralogy, and geochemistry of the physical and chemical fillings within karst caves. The caves in Ordovician carbonates were filled in Early Carboniferous in Lunnan area. The muddy filling in upper caves was deposited under subaerial fresh-water setting, while the muddy filling in lower caves was formed in the mixed water body of fresh-water and dominated sea water. Although most chemical fillings are suggested being precipated in the burial diagenetic environment after karstification but mineralogic and geochemical characteristics of some chemical fillings indicates they formed in meteoric environment during the karstification. It is obvious that the palaeokarst has been zoned in vertical profile. It can be divided into four units from top to bottom: surface karst, vadose karst, phreatic and tranquil flow zones. Between two types of limestone karst and dolostone karst are firstly differentiated in Tarim Basin, based on the comparison of features of each karst zone in limestone and dolostone regions. In Tabei area, the lowest depth of karstification is approximately 300 m below the Upper Ordovician unconformity interface, while the bottom depth of karstification in Tazhong area ranges commonly from 300 to 400 m, in rare cases may be up to 750 m below the upper Ordovician unconformity interface. In Lunnan and Tazhong areas, the palaeokarst morphology and the surface hydrosystem are firstly reconstructed based on the top of carboniferous "Shuangfeng limestone bed (Double-Peaks limestone)" as basal. According to the palaeomorphologic feature, karst topography can be divided into three units: karst upland, karst slope, and karst valley. Vadose zone was well developed in karst upland, and it can be found in a quite depth. Both vadose and phreatic zones were well developed in karst slope and upstream valley. In downstream valley, the karstification is not strong, the vadose and phreatic zones are thin in thickness. In Tazhong and Yingmaili areas, karstification is also developed in relict carbonate palaeo-hills which existed as isolated blocks admits clastic strata.

石笋微层序列的断代和信号研究

Based on chronological and climatologic analysis of many young stalagmites in Shihua Cave at Beijing and Water Cave in Benxi, Liaoning Province, this dissertation aims to discuss some key points on quantitative reconstruction of high resolution climate change from micro bands time series in young stalagmites. On chronological aspect of micro bands time series in young stalagmite, the uppermost micro bands were testified formed in the sampling year or the year before sampling from long term and in situ experiment in Shihua Cave at Beijing. Have been observed detailed under microscope, the micro bands were counted and compared with high resolution TIMS-230Th or ICP-MS U series dating, the results show that the micro bands are annual bands. The microscopic characteristics of annual bands in North China is as follows after studying lots of young stalagmites: the interface appears to be carved, and there is a light line adjacent to it, which moves back and forth slightly when adjusting the microscope slide. The cross dating of annual bands from different stalagmites is experimented in this thesis. On climatologically aspect of micro bands times series in young stalagmites, one significant problem is that the deposition trend resulting from the variation of the stalagmite shape. Various deposition trends have been discussed and corrected before climatologically analysis of micro bands series. And the whole year in situ observation and analysis of dripping water in Shihua Cave provide us new evidence for climate information reserved in stalagmites micro bands. The stalagmites in the same cave may contain different climate information due to the micro hydrological condition. The annual bands of young stalagmites collected from North China can be used to reconstruct past climate changes quantitatively. The warm season temperature (May, June, July, August) is reconstructed using two annual bands time series from Shihua Cave, Beijing, which corresponds to the warm/cool periods very well in Chinese history documents. The precipitation record of past 500 years is reconstructed using two stalagmite annual bands series from Shihua Cave, which is consistent to the dryness/wetness records derived from historical documents too.

工程地质三维可视化技术及其工程应用研究

Study of 3D visualization technology of engineering geology and its application to engineering is a cross subject which includes geosciences, computer, software and information technology. Being an important part of the secondary theme of National Basic Research Program of China (973 Program) whose name is Study of Multi-Scale Structure and Occurrence Environment of Complicated Geological Engineering Mass(No.2002CB412701), the dissertation involves the studies of key problems of 3D geological modeling, integrated applications of multi-format geological data, effective modeling methods of complex approximately layered geological mass as well as applications of 3D virtual reality information management technology.The main research findings are listed below:Integrated application method of multi-format geological data is proposed,which has solved the integrated application of drill holes, engineering geology plandrawings, sectional drawings and cutting drawings as well as exploratory trenchsketch. Its application can provide as more as possible fundamental data for 3Dgeological modeling.A 3D surface construction method combined Laplace interpolation points withoriginal points is proposed, so the deformation of 3D model and the crossing error ofupper and lower surface of model resulted from lack of data when constructing alaminated stratum can be eliminated.3D modeling method of approximately layered geological mass is proposed,which has solved the problems of general modeling method based on the sections or points and faces when constructing terrain and concordant strata.The 3D geological model of VII dam site of Xiangjiaba hydropower stationhas been constructed. The applications of 3D geological model to the auto-plotting ofsectional drawing and the converting of numerical analysis model are also discussed.3D virtual reality information integrated platform is developed, whose mostimportant character is that it is a software platform having the functions of 3D virtualreality flying and multi-format data management simultaneously. Therefore, theplatform can load different 3D model so as to satisfy the different engineeringdemands.The relics of Aigong Cave of Longyou Stone Caves are recovered. Thereinforcement plans of 1# and 2# cave in phoenix hill also be expressed. The intuitiveexpression provided decision makers and designers a very good environment.The basic framework and specific functions of 3D geological informationsystem are proposed.The main research findings in the dissertation have been successfully applied to some important engineering such as Xiangjiaba hydropower station, a military airport and Longyou Stone Caves etc.

岩溶洞穴系统溶解有机碳的时空演化及其环境意义

洞穴次生沉积物(尤其是石笋)所包含的古环境、古气候信息是当今研究的热点，但它所包含的环境气候信息对外界的响应灵敏度如何，这是最为关注的问题。石笋的微层厚度变化及荧光强度变化是来自洞穴上覆土壤中的有机碳沉积产生的，这些有机碳是由雨季早期冲刷进入洞穴形成的微层，微层厚度变化及荧光强度变化包含了环境(植被)、气候(温度和降水量)信息，它们可作为环境、气候替代指标使用，但需要进行现代环境、气候的校正，以往研究仅从某个侧面进行研究，系统研究有机碳在岩溶洞穴系统的演化过程较少。本论文通过对四个洞穴系统(凉风洞、七星洞、将军洞和犀牛洞)的溶解有机碳及其荧光系统的研究，探讨了溶解有机碳及其荧光的演化及其对环境气候的响应，根据分析论述，得出如下几点认识： 1． 通过对四个岩溶洞穴系统中DOC浓度月际、季节、年际变化研究，洞穴滴水在春季及夏初具有较大的DOC浓度，而在秋季变化最小、浓度也是最低的。滴水点出现DOC峰值的时间不一致，有的在春季、有的则在夏初，一方面反映降水时间的提前或推迟，另一方面也反映了水在洞穴顶板内的运移途径的长短等过程。个别滴水点能在不同时间出现不同的DOC浓度峰值，可能反映了滴水点对降水的响应灵敏，或不同的径流途径在时间上的提前或推迟，水动力条件的不同造成滴水补给源运移路径的差异应该是产生滴水点DOC浓度具有多个峰值的原因。由于洞穴次生沉积物在DOC的参与下形成，季节性的DOC高浓度产生较厚微层，但对降水敏感的滴水点可能产生了不同厚度的微层，不仅具有季节性微层，可能还能产生降水模式的微层。 2． 洞穴系统中溶解有机碳和荧光的空间变化分析上，得出溶解有机碳浓度在各个洞穴系统中纵向和横向上是有变化的。在滴水中滴水点间DOC浓度也有空间变化，而洞穴之间变化差异不明显，可能与土壤有机碳进入洞穴的运移途径有关；在土壤水中溶解有机碳浓度空间变化能反映了土壤有机碳的来源，即表层50cm以上的土壤层是输入土壤的有机碳主要来源。 3． 根据三维荧光光谱，四个岩溶洞穴系统的DOC的荧光类型可分为三个范围，即类富里酸、类蛋白和紫外类富里酸、类腐殖酸、类蛋白的混合荧光类型。在其它洞穴滴水的研究中未发现类腐殖酸类型的荧光峰，四个洞穴系统滴水中也不具有该类型荧光峰。在与植被类型的联系上反映出森林植被下的荧光波长变化较小，而土壤覆盖较连续的荧光强度较稳定。 4． 荧光波长的变化，反映了输入滴水中有机碳物质类型的差异，即有机碳在空间分布上的不均匀性和植被差异导致荧光波长的变化。从土壤水到洞穴滴水，溶解有机碳与荧光强度具有很好的线性相关性，表明洞穴滴水溶解有机碳是土壤有机碳运移至滴水中；土壤有机碳运移过程沿运移途径产生一系列变化，滴水DOC浓度低于土壤溶解有机碳一个数量级。土壤水DOC在将军洞的荧光强度除受外界因素影响，还受到内滤效应导致DOC浓度与荧光的强度线性关系不明显。在溶解有机碳和荧光的空间变化关系上，应联系表层环境对它们的影响，对它们充分认识才能得出合理的空间变化推论。 5． 荧光强度在洞穴滴水的变化趋势，一方面反映表层环境的变化，另一方面可能因水动力条件的不同，产生荧光性物质滤除效应，在DOC浓度变化较小的将军洞表现得最突出。在季节性水流输入的凉风洞和犀牛洞、和有滴水长期输入的七星洞和将军洞塘水，前三个洞穴塘水溶解有机碳及其荧光强度都明显高于滴水的，而后一洞穴塘水的低于滴水的，可能洞内蒸发作用对后者影响小，这样洞穴次生沉积除以表层环境的影响，其洞内环境的变化也可能是影响它的一个因素，但相对于表层环境变化，洞内的变化是微小的。 6． 从四个洞穴系统DOC变化来看，DOC浓度变化对植被类型变化不是很灵敏。从原生性喀斯特森林→灌丛草坡→灌草丛→刺丛草坡的岩溶洞穴系统，虽然土壤水DOC浓度变化较大，反映了输入土壤的及土壤中有机碳的分解难易程度，但在洞穴滴水中DOC浓度变化不是很明显，都显示相近的浓度水平。由于输入土壤的有机碳更新周期长，在水运移过程中受不同时间段降解的有机碳溶解，且来源不同的有机碳混合程度不同，导致不能很好地反映当年输入的有机碳的含量变化，应该是造成洞穴滴水DOC浓度不能很好区分植被类型的原因。 7． DOC浓度变化响应于降水量，也响应于气温。春夏季，当降水量达到一定雨量值(如有效降水量)时，入渗的雨水使表层有机物质溶入土壤水中，土壤水下渗到洞穴滴水中后，滴水DOC浓度较大，荧光强度也较大。降水对DOC浓度有稀释作用，是造成部分月份DOC浓度下降的原因。在7月份以前洞穴滴水DOC就已达到最大浓度，在8～10月份因气温高、降水量偏少，可能对微生物有抑制作用，造成其分解有机碳活动减弱，导致DOC浓度变化差异小。这反映了洞穴滴水DOC浓度与气候关系比较密切，进一步证实利用洞穴次生沉积物微层的厚度变化来反映气候变化是可行的，至少可以作为一个辅助指标来运用。 8． DOC及其荧光受多种因素影响，我们分析了pH、HCO3-、SIC、PPCO2、洞穴盖层厚度和岩石的溶解对它们的影响。分析表明洞穴盖层厚度和Ca2+、Mg2+离子浓度变化对它们的影响较大，pH变化范围小，认为它对DOC及其荧光的影响较小；HCO3-、SIC和PPCO2与DOC和荧光强度分别具有一些较好的线性关系(置信度=90%)，但总的趋势是线性关系不显著，这表明了HCO3-、SIC和PPCO2与DOC和荧光强度联系不明显，指出它们只是影响DOC及其荧光强度的一个次要因素，并不是主要因素。洞穴盖层厚度影响洞穴滴水DOC及其荧光，表明在应用洞穴次生沉积物记录指标反演洞穴环境变化的研究过程中，对于次生沉积物形成点的发生在洞穴顶板内的水文地化学过程应该有一个清晰的了解，才有可能获取完整、正确的信息。

喀斯特洞穴系统中稳定同位素地球化学特征及其环境意义

洞穴次生化学沉积物作为探索区域性、全球性气候变化规律和环境变迁史最重要的“信息库”之一，取得了不少有价值的研究成果。但同时，随着高分辨、短时间尺度气候-环境变化记录研究的开展与数据的进一步积累，也发现此类研究目前存在着一些问题与局限性。事实上，洞穴次生化学沉积物环境替代指标的形成经历了一系列复杂的过程，包含的影响因数相对较多。总的来说，其形成过程从大气降雨开始，穿越土壤层、洞穴盖板层到洞穴内滴水中CO2逸出、过饱和的CaCO3结晶和水中携带的不溶物沉淀。其中在不同的气候与环境条件下水与各层（如土壤层、表层喀斯特和潜水带等）中媒介之间发生的物理化学过程决定了环境替代指标的真实涵义。但目前有关这些替代指标的形成过程及其影响因子、适用性等方面的研究工作相当薄弱，尽管包括本文作者所在课题组在内的一些学者已认识到这一工作的重要性，零星做了一点工作，但还无法形成系统的认识。 在我国西南部，缺少类似我国北方的巨厚黄土堆积，但岩溶发育，且连片分布，其面积居世界首位（东亚喀斯特片区的中心）。因此，在该地区气候环境变迁史研究中，环境记录“档案”——洞穴次生化学沉积物在该方面所起的作用具有与北方黄土一样的重要意义。该研究为利用洞穴次生化学沉积物的地球化学特征恢复古生态环境意义的研究奠定坚实的理论基础。基于此，我们选择我国西南喀斯特发育最为典型的贵州作为研究区域，通过对分布于境内不同地方100多个洞穴进行实地考察和综合评判之后，筛选出一个系列的4个喀斯特洞穴作为研究对象，分别选取一定数量采样点进行采样。在前人研究的基础上，更加深入系统地对该4个洞穴系统中的稳定同位素（碳和氧同位素）进行研究。 分别系统地采集了4个洞穴系统中的大气、植物、土壤、土壤空气、土壤水、基岩、泉水、洞穴滴水、洞穴空气、塘水、潭水和滴水对应的洞穴次生化学沉积物等，现场测试pH值、电导率（Cond.）和气温（T）等，室内分别测试了稳定同位素和其他相关指标（如各种离子浓度等），以期开展不同生态环境条件下正在形成的洞穴次生化学沉积物及其对应的洞穴滴水的地球化学特征的比较研究，揭示它们对气候环境变化的响应机制，即稳定同位素等洞穴次生化学沉积物环境替代指标的现代形成过程以及各种影响因子。 本研究主要取得以下几点认识： 1. 虽然缺乏同气候、等海拔和生物量在10~90 t/hm2之间的植被序列洞穴的对比，以及对土壤有机质和土壤微生物活性等的相关试验研究，但根据分析仍可获知，洞穴化学次生沉积物的碳同位素的生物量效应是由植物碳同位素及土壤CO2微生物分馏作用机制共同制约。也就是说，洞穴沉积物碳同位素信号所反映的信息包括植被碳同位素组成及其生物量所控制的土壤性质（如微生物等），并不一定指示地表植被的C3/C4比例变化，甚至也不一定指示乔、灌、草的比例，当然也不仅仅是植被覆盖变化的简单体现。总之，生物量效应在横向上是存在的，它至少部分控制着洞穴化学次生沉积物碳同位素的变化，在对石笋等碳同位素的高分辨率解译过程中是不容忽视的。其机理可能是，生物量的大小控制土壤性质（营养和含水量等），进而激发或抑制土壤微生物群落的生长和发育，从而影响土壤有机质的分解过程最终导致次生沉积物δ13C值的变化。 2. 贵州喀斯特地区δ13CSOC与源植物的δ13C差值最大达8‰以上，其主要受土壤水热条件、质地和pH值控制。由此可见，δ13CSOC动态总体上反映了植被破坏历史。不过由于未进行具体年限测定，植被受破坏的具体时间未知。因此，今后除了需对SOC含量等问题进行系统的研究外，14C定年以及喀斯特地区更多土壤剖面等的工作也有待进一步开展。 3. 洞穴水在下渗过程中普遍发生了混合作用，致使从上（地表）到下（洞穴）δ13CDIC值变化幅度变小。除了QXD和JJD中δ13CDIC值偏重的滴水外，基岩对滴水碳同位素组成的影响都相对较小，而各洞穴中滴水（沉积物）等碳同位素组成与洞穴上覆植被等有关，是生态环境的真实记录。LFD中各种洞穴水δ13CDIC值之间基本上都达到或接近同位素平衡，且与洞穴系统的生态环境有很好的相关关系（非常显著的时间变化）；QXD和JJD之间的洞穴水（除土壤水外）δ13CDIC动态极为相似，即同一洞穴同期不同滴水点滴水δ13CDIC存在很大差异，可能与上覆土壤受到严重破坏导致基岩贡献率相对较高有关，而其中的几个滴水与相应沉积物的同位素不平衡可能是沉积速率太慢或沉积间断所致；XND尽管土壤水与JJD的有相似的特征，但其洞穴滴水平均δ13CDIC之间基本一致且与相应沉积物接近同位素平衡。因此，4个洞穴中，LFD可能是最为适合进行高分辨率和短时间尺度（如季节甚至月份）研究的洞穴。另外，对于文中出现的滴水（上）δ13CDIC偏重于滴水（下）的现象以及土壤中水气平衡的影响因素等还有待今后进一步研究。 4. 研究的4个洞穴系统大气降雨尽管主要受东亚季风控制，但来源不完全一致，还不同程度地受西南夏季风等影响。LFD和QXD受东亚季风影响程度相对高于XND和JJD，西南季风的影响程度恰好相反。 5. 尽管地表蒸发作用对表层（10cm以上）土壤水δ18O有一定的控制作用，但是较深（如10cm以下）土壤水基本不受影响；同位素示踪结果显示，土壤水和洞穴滴水对大气降水均有响应，但响应时间不一，可能与上覆物质（植被、土壤和基岩等）结构构造等控制的水文学特征和有效大气降水量等有关；喀斯特土壤的高度异质性导致土壤水运移机制的不同，从而影响混合作用的过程，最终导致洞穴系统同期土壤水δ18O存在一定差异；雨水在下渗过程中的不同来源水混合作用，是不同类型水δ18O时间上变化幅度不同的主要原因；同一洞穴不同滴水δ18O之间的差异可能与水文学特征不同有关；水化学性质（如SIC）控制沉积物的沉积过程从而影响同位素平衡。 由此可见，利用研究的4个洞穴系统中洞穴次生化学沉积物中氧同位素恢复和重建古降水量的高分辨率短时间变化是可行的。但我们也应注意到，在利用洞穴次生化学沉积物恢复和重建古降水量之前有必要寻找合适的方法（如利用Hendy法则等）判断是否达到同位素平衡。不是所有点沉积物都真实地记录着滴水（大气降水）同位素信号的，尤其在QXD和JJD中，一半左右的滴水点沉积物没有达到同位素平衡。这些均显示出在高分辨率短时间尺度古气候研究中，了解沉积物的形成过程对于准确解译洞穴过去环境变化具有重要意义。