北极阿拉斯加巴罗地区Elson泻湖的沉积古环境研究

Ｅｌｓｏｎ泻湖长６０ｃｍ的钻孔岩芯沉积构造、结构、颗粒性状分布等分析表明，该岩芯经历三期差别明显的沉积期，各期沉积动力环境不同。下段搬运介质单一，搬运动力较强，沉积环境相对稳定；上段搬运动力明显减弱，多源介质混合掺杂作用明显，沉积环境稳定性较差；中段为过渡期，各性状介于上、下段之间。     

晚更新世以来布兰斯菲尔德海峡冰－海沉积特征

综合分析和研究了采自布兰斯菲尔德海峡主体海槽中ＰＣ１０孔（７５３ｃｍ长）的全部室内外资料：岩芯、粒度特征、矿物组分、生物尸体群和年代学等，指出了整个岩芯柱代表了区内１１２．５ｋａ以来冰－海环境的沉积。沉积作用包括生物硅质沉积，火山碎屑沉积和浊流沉积等。其中生物硅质沉积作用，不论在高水位／间冰期或低水位／冰期均占主导地位，不同的是低水位／冰期沉积物中陆源碎屑物含量低且矿物成分和岩屑成分较单一，而高水位／间冰期则相反，且前者沉积速率低于后一时期，这一沉积特点与中低纬度情况有所不同     

福建中亚热带天然阔叶林与人工林对比评价Ⅰ.水土资源的保持与维护

相同立地和伐前林分、年龄相近的天然阔叶林与人工杉木森对比评价结果表明：天然阔叶林地上部分有较持水量和０ｃｍ～４０ｃｍ土壤蓄水量均大于人工杉木林;天然阔叶林０ｃｍ～２０ｃｍ土壤有机质含量高于人工杉木林;全氮、全磷含量高于人工杉木林,天然阔叶林涵养水源功能及维护土壤肥力功能显著优于人工杉木林。     

泰国暖颂钾盐矿床粗粒岩盐沉积特征及其成因研究

老挝－泰国呵叻高原钾盐矿床储量大、品位高、易开发,粗粒岩盐在该钾盐矿床中普遍发育,其对水成盐转化、水体掺杂过程、钾盐富集演化等沉积环境具有重要的指示作用,然而,关于其成因至今仍未有详细报道。利用岩石学、显微岩相学和沉积学方法对呵叻高原西南部暖颂县钾盐矿床钻孔岩芯第一沉积旋回粗粒岩盐的成因进行了研究,得到如下结论:(1)粗粒岩盐主要有 3种成因,浅水环境中蒸发浓缩阶段原生生长,浅水环境中干盐湖阶段胶结生长,埋藏环境中孔隙卤水重结晶生长;(2)根据粗粒岩盐的成因、沉积规律和钻孔岩性特征可将马哈萨拉堪组下盐层沉积演化划为 5个沉积阶段:岩盐沉积稳定阶段、岩盐沉积过渡阶段、光卤石沉积初期阶段、光卤石沉积稳定阶段和次生岩盐沉积阶段;(3)研究区钾盐矿床整体的沉积环境为浅水。粗粒岩盐在矿层中的赋存特征、成因以及与其它岩相的组合特征共同表明了钾盐在沉积过程受到了不同程度的淡水稀释和埋藏后的改造作用。     

北威尔士北美云杉林土壤水运动规律的研究

本文论述了北威尔士北美云杉林〔Ｐｉｃｅａｓｉｔｃｈｅｎｓｉｓ（Ｂｏｎｇ）Ｃａｒｒ〕土壤非饱和水在土壤剖面上的垂直和水平方向的时空变化过程及规律。结果表明，表层至１０ｃｍ深和３５～５０ｃｍ深的土壤层内非饱和水含量始终高于１０～２０ｃｍ和２０～３５ｃｍ深两层的非饱和水含量。土壤非饱和水有从上向下和从下向上补给中间层的规律。受水势梯度的影响，犁沟内非饱和水可以侧向补给相邻畦埂的土壤。在监测期，土壤中没有饱和水和过饱和水运动过程出现     

长江口潮滩有机质稳定碳同位素时空分布与来源分析

通过测定长江口潮滩悬浮颗粒有机质和表层沉积有机质在枯水季节 (2006年2月 )和洪水季节 (2006年8月 )的稳定碳同位素值,对有机质潜在来源及局部岸段改造作用进行了分析。结果显示,悬浮颗粒有机质稳定碳同位素值在2月明显低于8月,变化范围分别在-25.8‰~-23.4‰和-25.1‰~-22.9‰,主要是受径流量枯洪季变化和浮游生物生长季节变化两种因素的叠加作用。表层沉积有机质2月和8月的稳定碳同位素分别为-25.0‰~-20.4‰和-24.7‰~-19.5‰,季节变化不明显,主要来自悬浮颗粒物的沉降。除受大背景环境因素影响,局部环境对潮滩有机质也有一定的改造作用,污水、支流河水的输入对悬浮颗粒有机质碳同位素有一定的影响,埋藏的潮滩植物和底栖微藻则对沉积有机质有部分贡献。     

察尔汗盐湖首采区上盐层中光卤石分布

本文根据１９８７、１９９１和１９９２年１２０个钻孔剖面岩性资料得出，察尔汗盐湖首采区及其附近地区上岩层中光卤石主要分布在首采区范围内，首采区外的东部、北部和东南部亦有少量分布．其分布井段一般为埋深３～１０ｍ．光卤石主要分布在中细粒致密（或松散）和含粉砂中粗粒松散石盐层中，多呈散状或似层状分布；在碎屑层中亦有少量光卤石分布．并对光卤石成因和沉积演化进行了初步讨论．     

毛乌素沙区风沙土机械组成及含水率的季节变化

以定位观测资料为基础,对毛乌素沙区０～１００ｃｍ层内流动风沙土、天然油蒿和臭柏灌丛及沙柳和樟子松人工林下风沙土的含水率和机械组成进行了研究。结果表明,整个生长季节流动风沙土的含水率较稳定,年平均值在３．０％左右;油蒿、臭柏、沙泖和樟子松下的固定、半固定风沙土含水率变化较大,年平均值为１％～２％。风沙土含水率主要受降雨、植物蒸腾和土面蒸发的影响,其垂直分布可分为０～１０ｃｍ的干沙层和１０～１００ｃｍ的活跃层;季节变化表现为４～６月和９～１１月的失水期、７～８月的降水补给期、翌年４月以前的冻结滞水期。     

异龙湖湖泊沉积对流域人类活动的响应

通过对异龙湖短钻岩芯沉积物粒度、碳酸盐以及有机质含量等环境代用指标研究,结合文献资料和当地气象数据并参考实验室其他项目组137Cs-210Pb方法建立的年代标尺,讨论了异龙湖流域1880年以来的环境变化和人类活动对湖泊沉积环境的影响。结果表明:岩芯35~25 cm段(1880—1936年)碳酸盐含量、中值粒径均值较高,表明这一时期为暖湿气候,TOC含量处于低值且平缓,证实人类活动对周围环境影响较小,湖泊环境变化的影响因素以自然因素为主;至25~15 cm段(1936—1996年)碳酸盐含量明显下降,有机质含量快速增加,指示湖泊沉积环境受人类活动影响强烈,碳酸根离子等其他化合物含量、反应条件、过程及碳酸盐沉淀保存条件发生改变,在此种情况下,指标已不能指示湖泊环境变化;岩芯15~0 cm段(1996—2013年)沉积物粘土含量升高,砂含量降低,应与异龙湖流域防护林工程有关,这一时期的指标特征表明人类活动强度较之前有所减弱,并且开始有意识地恢复流域生态。     

连环湖他拉红泡重金属和营养元素的沉积记录

通过对连环湖他拉红泡柱状沉积岩芯TE中重金属元素、有机质(OM)、总氮(TN)、C/N及总磷(TP)等多指标综合分析,研究了重金属与营养元素的含量变化特征及可能的影响因素,并采用聚类分析方法判别重金属元素的可能污染来源.结果表明,岩芯深部18.5~12.5 cm,大部分元素含量波动幅度较小,C/N值在20左右波动,较稳定,元素属自然状态下的沉积;岩芯中部12.5~5.5 cm,Li、Mn、Ni、Fe、Zn、OM和TP含量呈现减小趋势,经参考元素校正后初步证实受干旱气候的影响,C/N值波动较大,均值高于第一阶段,Mn、Ni和Cu经校正后含量基本未发生变化,仍为自然状态下的沉积,而Fe、Pb、Cr和Zn校正后含量呈增大趋势,推测受到人类活动污染排放的影响;岩芯上部5.5~1.5 cm,重金属和营养元素含量均缓慢增加,C/N值有所减小,重金属元素含量高值接近自然沉积时的含量值,表明重金属污染程度较轻,尚未对湖泊水体及生物达到毒害作用,而营养元素含量高值远大于自然沉积时的含量值,说明湖泊富营养化程度明显加重,已对水体及生物构成危害,应作为治理水污染工作的重点.     

Surface textures of quartz grains from a core at the Prydz Bay,Antarctica

ＳｕｒｆａｃｅｔｅｘｔｕｒｅｓｏｆｑｕａｒｔｚｇｒａｉｎｓｆｒｏｍａｏｒｅａｔｔｈｅＰｒｙｄｚＢａｙ，ＡｎｔａｒｃｔｉｃａTX＠王祥珍＠吴时国＠李传荣＠陈虹勋＠罗又郎ＳｕｒｆａｃｅｔｅｘｔｕｒｅｓｏｆｑｕａｒｔｚｇｒａｉｎｓｆｒｏｍａｃｏｒｅａｔｔｈｅＰｒｙ...     

长江口潮滩有机质来源的C、N稳定同位素示踪

依据长江河口潮滩自然环境特征和受人文活动影响的差异性,沿长江河口南岸潮滩选取了12个典型的监测站位,并分别于洪水季节 (7月份) 和枯水季节 (2月份) 在各监测站位进行了表层 (0~2 cm) 沉积物样品的采集。对表层沉积物有机质中稳定碳、氮同位素进行分析与测试发现,7月份稳定碳同位素值普遍低于2月份的稳定碳同位素值,其变化范围分别为 -29.8‰ ~ -23.7‰和-27.3‰ ~ -25.6‰;7月份和2月份稳定氮同位素分别为1.0‰ ~ 5.5‰和1.7‰~ 7.8‰。研究区域内,稳定碳、氮同位素的地区分布和季节变化特征揭示,有机质中的稳定碳、氮同位素组成不仅受陆源和海源有机质输入量之间消长变化的影响,同时一系列的生物地球化学过程、人为有机质的输入和沉积物粒度与叶绿素对碳、氮同位素组成均存在不同程度的改造作用。此外,利用稳定碳同位素质量平衡混合模型,还对陆源有机质输入量的贡献率进行了初步定量估算。     

南极普里兹湾柱样中石英颗粒的表面结构

本文统计分析了南极普里兹湾陆坡区一个柱样（ＮＰ９５１）１３个层位的石英颗粒的形态和表面结构。石英表面呈现出强烈的冰川运动和较弱的化学溶蚀－沉淀作用留下的表面特征，表明该沉积物主要是处于低能海洋环境中的冰碛物。石英颗粒因化学溶蚀－沉淀作用形成的组合表面特征的定量统计结果与矿物的Ｘ射线衍射和微体古生物的分析结果相对应，能较好地解释该海区经历的沉积环境和古气候变化。     

库姆塔格沙漠东南缘BL剖面粒度记录的全新世快速气候事件

地质历史过程中全新世时期是一个温暖湿润的间冰期气候过程,中间出现过多次变冷或变干的快速气候事件。BL剖面位于库姆塔格沙漠东南缘,是一典型的风成砂黄土沉积地层,沉积厚度约350 cm。通过沉积地层光释光测年和沉积物粒度变化分析,结果显示：（1）BL剖面沉积的年代始于8.3 ka,处在全新世早期;（2）区域干旱气候条件下,反映冬季风的代用指标则以粗端组分含量为主,BL剖面沉积物平均粒度受到颗粒粗端的影响较大,对比3个不同粗颗粒组分含量所指示的古气候变化,选用>110 μm的沉积物颗粒组分含量作为冬季风研究的替代性指标,具有较好的指示意义;（3）剖面粒度对全新世中晚期的6次气候快速变化过程均有不同程度的记录,其特点是对全球性冷事件敏感性较强,对干旱事件响应较弱。对库姆塔格沙漠地区全新世气候过程的研究,可为极端干旱区域气候对全球气候变化过程的响应提供一定借鉴。     

Late Quaternary glacial－marine sedimentation in the Bransfield Strait off northeast Antarctic Peninsula

（段威武）（钟和贤）（李扬）ＬａｔｅＱｕａｔｅｒｎａｒｙｇｌａｃｉａｌ－ｍａｒｉｎｅｓｅｄｉｍｅｎｔａｔｉｏｎｉｎｔｈｅＢｒａｎｓｆｉｅｌｄＳｔｒａｉｔｏｆｆｎｏｒｔｈｅａｓｔＡｎｔａｒｃｔｉｃＰｅｎｉｎｓｕｌａ￥ＤｕａｎＷｅｉｗｕ；ＺｈｏｎｇＨｅｘ...     

Geochemical effects of rapid sedimentation in aquatic systems: minimal diagenesis and the preservation of historical metal signatures

Rapid sedimentation exerts a pronounced influence on early sedimentary diagenesis in that there is insufficient time for a sediment particle to equilibrate in any one sediment layer before that layer may be displaced vertically by another layer. These sedimentation patterns are common in surface-water reservoirs whose sedimentation rates (1-10 cm yr^-1) are several orders of magnitude greater than those for natural lakes (0.01-0.5 cm yr^-1).Two examples of the effects of rapid sedimentation on geochemical metal signatures are presented here. Interstitial-water data (Fe) from two sites in the Cheyenne River Embayment of Lake Oahe on the Missouri River illustrate the effects of changing sedimentation rates on dissolved species. Rapid burial during high-flow yrs appears to limit early sedimentary diagenesis to aerobic respiration. Solid-phase metal data (Pb) from a site in Pueblo Reservoir on the upper Arkansas River in Colorado appear to record historical releases by flooding of abandoned mine sites upstream in Leadville, Colorado. Interstitial-water ammonia and ferrous Fe data indicate that at least one interval at depth in the sediment where solid metal concentrations peak is a zone of minimal diagenesis.The principal diagenetic reactions that occur in these sediments are aerobic respiration and the reduction of Mn and Fe oxides. Under slower sedimentation conditions, there is sufficient time for particulate organic matter to decompose and create a diagenetic environment where metal oxides may not be stable. The quasi-steady-state interstitial Fe profiles from Tidal Potomac River sediments are an example of such a situation. This occurs primarily because the residence time of particles in the surficial sediment column is long enough to allow benthic organisms and bacteria to perform their metabolic functions. When faster sedimentation prevails, there is less time for these metabolic reactions to occur since the organisms do not occupy a sediment layer for any length of time. Also, the quantity and quality of the organic matter input to the sediment layer is important in that reservoirs often receive more terrestrial organic matter than natural lakes and this terrestrial organic matter is generally more refractory than autochthonous aquatic organic matter.     

巴丹吉林沙漠晚更新世沉积物矿物学特征及其指示意义

巴丹吉林沙漠是研究亚洲内陆干旱化等古环境问题的重要窗口。以沙漠东南缘巴润宝日陶勒盖剖面为研究对象,通过详细的薄片矿物学、X射线衍射半定量及粒度等方法指标,综合分析沉积物的结构成熟度和成分成熟度等矿物学特征,恢复该地区在晚更新世沉积环境变化。结果表明：（1） 66.8 ka之前沉积的矿物碎屑分选性好、磨圆较好,稳定矿物含量高;66.8 ka之后,矿物分选性差、磨圆差,稳定矿物含量均下降,粘土矿物增加。（2） 66.8 ka之前沉积物以中砂为主,66.8 ka之后以细砂为主。研究表明巴丹吉林沙漠东南缘66.8 ka前后存在一次沉积环境突变,由风沙沉积转变为湖相沉积,可能代表了一次典型的东亚夏季风增强事件,推测与低纬西太平洋温度升高相关。对于巴丹吉林沙漠东南缘沉积物矿物学的相关认知有助于理解沙漠中沉积环境的转换过程及其驱动因子,并为重建沙漠千年尺度的古环境与古气候演变提供数据参考。     

REMOBILIZATION AND ACCUMULATION OF IODINE IN MARINE SEDIMENTS, WESTERN ANTARCTIC OCEAN

Remobilization and accumulation mechanisms of iodine in marine sediments, which are divided into several geochemical environment, are studied. The result shows that iodine is characteristically rich in organic fractions of the sediments on the bottom of bay and pelagic sediments. However, it may be associated with oxyhydroxide and adsorptive phase in a highter percentage at the continental shelf and hemipelagic sediments. The environmental characteristics of remobilization of iodine in surficial sediments are similar to that of iron, that is, it is remobilized on anoxic conditions and converted into solid phases when it is in oxic environments, though the iodine does not act as the electron acceptor. The processes of adsorption and oxidation are responsible for the value of I_t/C_(org) in excess of that of planktonic materials other than the organic fraction in surficial sediments. It is a comprehensive effect of organism decomposition, oxyhydroxide reduction, particulate adsorption and pore water diffu     

Lacustrine Sedimentary Organic Matter Records of Late Quaternary Paleoclimates

Identification of the sources of organic matter in sedimentary records provides important paleolimnologic information. As the types and abundances of plant life in and around lakes change, the composition and amount of organic matter delivered to lake sediments changes. Despite the extensive early diagenetic losses of organic matter in general and of some of its important biomarker compounds in particular, bulk identifiers of organic matter sources appear to undergo minimal alteration after sedimentation. Age-related changes in the elemental, isotopic, and petrographic compositions of bulk sedimentary organic matter therefore preserve evidence of past environmental changes.We review different bulk organic matter proxies of climate change in tropical and temperate sedimentary records ranging in age from 10-500 ka. Times of wetter climate result in enhanced algal productivity in lakes as a consequence of greater wash-in of soil nutrients, and these periods are recorded as elevated Rock-Eval hydrogen indices, lowered organic C/N ratios, less negative organic 13C values, and increased organic carbon mass accumulation rates. Lowering of lake water levels, which typically depresses algal productivity, can also cause an apparent increase in organic carbon mass accumulation rates through suspension of sediments from lake margins and redeposition in deeper basins. Alternations between C3 and C4 watershed plants accompany climate changes such as glacial/interglacial transitions and wet/dry cycles, and these changes in land-plant types are evident in 13C values of organic matter in lake sediments. Changes in climate-driven hydrologic balances of lakes are recorded in D values of sedimentary organic matter. Visual microscopic examination of organic matter detritus is particularly useful in identifying changes in bulk organic matter delivery to lake sediments and therefore is important as an indicator of climate changes.     

Organic geochemical record of environmental changes in Lake Dianchi,China

In order to investigate the natural ecosystem of Lake Dianchi and to assess its anthropogenic impacts, a stratigraphic study of bulk and molecular compositions of organic matter was conducted using a 63-cm long sediment core. The results show that two apparent environmental changes occurred during the evolution of Lake Dianchi: (1) the first change occurred in the 43–63 cm sediment depth, and was revealed by the amount and the composition of organic matter in the stage. Natural changes were possibly major factors responsible for triggering the environmental change, but the influence of human activities could not be excluded. Subsequently, the lake entered into a relatively stable and oligotrophic stage, which maintained until 20-cm sediment depth. (2) Eutrophication started in the upper 20 cm depth. Human activities became a major factor influencing environmental changes in this stage. Vertical profiles of various organic geochemical variables in the upper 20-cm sediments show evidence that primary productivity of the lake increased progressively and that the lake started eutrophic. Especially in the uppermost 10 cm, notable excursions to less negative δ¹³C_org and δ¹⁵N_total and high TOC concentrations have recorded an abrupt change in the lacustrine environment, suggesting that the lake entered a hypereutrophic stage. In addition, enhancement of αβ-hopanes reflects the contribution of fossil fuels to the lake sediments.