黄河三角洲典型潮汐湿地碳、氮、磷生物地球化学特征   总被引：4，自引：0，他引：4  

曹磊  宋金明  李学刚  袁华茂  李宁  段丽琴  王启栋 《海洋科学》2015,39(1):84-93

选择位于黄河三角洲的广饶潮汐湿地为研究对象,对比了在不同的植被覆盖和水文条件下潮汐湿地土壤碳、氮、磷元素的垂直分布及生态化学计量学特征。结果表明,在芦苇(Phragmites australis)覆盖下的GRA2区域沉积物总有机碳(TOC)和总氮(TN)含量明显高于碱蓬(Suaeda salsa)覆盖下的GRA1区域。GRA1柱样TOC含量均值为1.798 mg/g,而GRA2柱样则为3.109 mg/g。GRA1柱样的TN含量范围在0.108~0.213 mg/g,均值为0.165 mg/g,而GRA2柱样TN含量范围则为0.307~0.473 mg/g,均值为0.353 mg/g。总体上,总磷(TP)含量的变化水平相对于TOC和TN来说较大,其垂直变异系数较高。而与TOC和TN相反的是,GRA2柱样中TP含量均值为0.298 mg/g,低于GRA1的0.388 mg/g,这可能跟GRA2区域芦苇的生长比碱蓬需要吸收更多的P元素有一定关系。研究区域沉积物C、N、P元素生态化学计量学比值普遍较低。相对较高的C/N值,较低的C/P值和N/P则显示黄河三角洲潮汐湿地的生物地球化学过程可能更多地受营养元素N和P等的限制,而前者可能是主要限制因素。本研究可为滨海湿地对全球碳和氮的储存提供基础数据,为滨海湿地可持续发展的管理和保护提供科学依据。  相似文献   

BDS/GNSS精密单点定位性能分析     

孙大伟  艾孝军  贾小林  陈尔东 《大地测量与地球动力学》2022,42(11):1111-1116

首先采用国际上通用的德国地学中心（GFZ）与武汉大学（WHU）精密产品,对GNSS精密卫星轨道和精密钟差产品精度进行初步评估;然后基于WHU精密轨道和钟差产品对18个分布于东半球的MGEX地面站进行多系统定位测试,同时也对BDS的B1I/B3I与B1C/B2a两组新、旧频点的精密单点定位性能进行对比分析。结果表明：1）四大导航系统（GPS、GLONASS、BDS、Galileo）的卫星轨道产品精度均在cm级,精密钟差内符合精度均优于0.1 ns,北斗三号（BDS-3）卫星钟精度相比北斗二号（BDS-2）有显著提升。2）亚太地区BDS的定位精度优于其他3个系统;在其他地区,GPS定位精度最优（与Galileo基本相当）,优于BDS和GLONASS的定位结果。3）BDS PPP平均收敛时间静态模式约为50.33 min、动态模式约为77.83 min,收敛速度略低于GPS、Galileo,优于GLONASS。4）B1C/B2a与B1I/B3I双频消电离层组合PPP定位性能基本相当。  相似文献   

四川盆地三叠系飞仙关组气藏储层成岩作用研究拾零   总被引：33，自引：0，他引：33  

王一刚  文应初  洪海涛  夏茂龙  何颋婷  宋蜀筠 《沉积学报》2007,25(6):831-839

近年来在四川盆地三叠系飞仙关组鲕粒白云岩储层中发现的高含硫天然气三级储量已近1×1012 m3。鲕粒白云岩储层集中分布在含蒸发岩的层序中,储层中有残余石膏、硬石膏及它们的模孔、方解石铸模（假象）等,表明白云石化流体与蒸发海水有关。白云石化由层间古暴露面向下增强的成岩层序说明这种白云石化是成岩早期发生的,并可能有大气降水与蒸发海水混合的影响。白云岩样品各结构组分氧、碳同位素微区测试数据差别显著,这说明采用岩石混合样做研究白云石化成因的地球化学分析可能导致误解。飞仙关组的白云岩中多数保存了原岩结构幻影、结构残余或原岩的全部结构说明白云石化过程是等体积交代。白云岩储层中的孔隙是各种溶蚀孔而非白云石化等摩尔交代的体积收缩孔。飞仙关组高含硫气藏储层中沥青和溶蚀孔的关系表明深埋晚期溶蚀孔最发育。在溶液中碳酸的电离常数大大高于氢硫酸,飞仙关组高含硫气藏天然气组分中的CO2相对于H2S的质量亏损和储层中有富轻碳的高温方解石充填晚期溶孔、裂缝表明储层中的晚期溶解作用是由硫酸盐热还原过程（TSR）中生成的CO2引起的。  相似文献   

广东四会古森林地下生态系统¹⁴ C地层年代学研究^*   总被引：1，自引：1，他引：0  

丁平  沈承德  易维熙  刘克新  丁杏芳  付东坡 《第四纪研究》2007,27(4):492-498

运用AMS-¹⁴ C定年技术,研究了被埋藏水松古木的发育和死亡时间以及土壤剖面中总有机碳的¹⁴ C表观年龄和细根的¹⁴ C年龄。结果表明:该地区的水松古木开始发育和死亡的时间大致为4~3kaB.P. 。根据土壤有机碳¹⁴ C的表观年龄,该土壤剖面的¹⁴ C年代地层可以分为3层,分别为:1)表层,2634±32~3305±29aB.P. ; 2)腐殖层,3305±29~3813±31aB.P. ; 3)基底,3813±31~4544±33aB.P. 。基底、腐殖土层和表层的沉积速率分别为0.55mm/a, 4.33mm/a和0.26mm/a。 细根的¹⁴ C年龄变化范围为2290±29~3542±28aB.P. ,较同层位的土壤有机碳的年龄年轻。腐殖层土壤中有机碳含量高达33 ％ ~46 ％ ,大多数有机碳仍处于未分解状态。该地区自4~3kaB.P.以来,环境演化可能经历了由陆到沼泽再到被水淹没最后又变成陆地的过程,植被从以水松为优势种的森林群落演化成当前以常绿阔叶林为主的森林生态群落,气候和海平面变化、地质构造运动和人类活动是这种环境演化的主要驱动因子。  相似文献   

The marine 14C age of the Vedde Ash Bed along the west coast of Norway     

Stein Bondevik  Jan Mangerud  Steinar Gulliksen 《第四纪科学杂志》2001,16(1):3-7

Articulated molluscs, sea urchins and barnacle fragments close to the Vedde Ash Bed in a shallow marine deposit on the west coast of Norway have been ¹⁴C dated. The weighted mean of four dates from a sediment slice 8 cm thick centred on the Vedde Ash Bed is 10920 ± 24 ¹⁴C yr BP. The most accurate ¹⁴C age of the Vedde Ash from terrestrial plant macrofossils is 10310 ± 50 yr BP. The difference is the ¹⁴C reservoir age for coastal water at the west coast of Norway during the mid‐Younger Dryas and equals 610 ± 55 yr. This is 230 yr older than the reservoir age for the Bølling/Allerød and for the present day in this area. The result supports earlier conclusions of a higher reservoir age for the Younger Dryas in the North Atlantic and Nordic Seas, although our reservoir age of 610 ± 55 yr is a few hundred years younger. This suggests that the ¹⁴C reservoir age at Vedde Ash time may increase from coastal water towards the open North Atlantic and Nordic Seas. Copyright © 2001 John Wiley & Sons, Ltd.  相似文献   

Fluvial incision and channel downcutting as a response to Late‐glacial and Early Holocene climate change: the lower reach of the River Meuse (Maas), The Netherlands     

L. A. Tebbens  A. Veldkamp  W. Westerhoff  S. B. Kroonenberg 《第四纪科学杂志》1999,14(1):59-75

Detailed fieldwork and new extensive ¹⁴C dating of residual channel infillings provide data for the reconstruction of the Late‐glacial channel downcutting and incision history of the Venlo–Boxmeer lower reach of the River Meuse (= Maas) in the southern Netherlands. Within a period of 500–1300 yr after Late‐glacial climatic amelioration, the Meuse responded to increased discharges and decreased sediment supply by adjusting the width/depth ratio of its channels. Two main phases of channel downcutting are followed by two main phases of floodplain lowering and narrowing, indicating net floodplain degradation by the fluvial system as a non‐linear response to Late‐glacial and Early Holocene climate change. Some 1300 yr after initial late‐glacial warming, channels downcut rapidly during the Early Bølling (13.3–12.5 kyr BP) and adopted a high‐sinuosity meandering style. Channel downcutting paused around 11.9 kyr BP, possibly in response to rising groundwater levels and/or the Older Dryas cooling event. Between 11.9 and 11.3 kyr BP a new floodplain was formed. Then, lateral erosion took place and initiated a first phase of 2.6 m floodplain lowering during the Late Allerød. Gradual climate deterioration during the Allerød progressively broke up soils and vegetation cover, from 11.3 to 10.9 kyr BP. The Meuse gradually adjusted to an increased ratio of sediment supply over transport capacity through higher width/depth ratios. Main channels became shallower and adopted a low‐sinuosity pattern, finally culminating in a braided river system during the Younger Dryas. The final Holocene warming resulted, within 500 yr, in renewed rapid channel downcutting by a single low‐sinuosity channel during the Early Preboreal, followed by a second phase of 1.8–2.8 m floodplain lowering. Copyright © 1999 John Wiley & Sons, Ltd.  相似文献   

A Synoptic Snapshot of the East Cape Eddy （ECE）     

LIU Wei  and LIU Qinyu Physical Oceanography Laboratory & Ocean-Atmosphere Interaction  Climate Laboratory  Ocean University of China  Qingdao  P. R. China 《中国海洋大学学报(英文版)》2005,4(1):8-13

1Introduction The East Australian Current(EAC)partially sepa-rates from the coast of Australia(Godfrey et al.,1980)and subsequently flows eastward along the Tas-man Front(TF)(Warren,1970).When the east-ward flow reaches the northernmost point of New Zealand,it turns southeastward and becomes the East Auckland Current(EAUC).The flow that goesround the East Cape is named the Ease Cape Current(ECC).The ECC separates from North Island and proceeds eastward to the north of the Chatha…  相似文献   

陕西华阴兴乐坊遗址家养动物的饲养模式及对先民肉食资源的贡献     

胡耀武  张昕煜  王婷婷  杨岐黄  胡松梅 《第四纪研究》2020,(2):399-406

通过动物骨的稳定同位素(C、N)分析,揭示家养动物的饲养模式及对先民肉食资源的贡献,是动物考古研究的重要组成之一.关中地区,是庙底沟文化(约5500年前)的主要核心分布区域之一.目前,对该地区和该时间段内家养动物的饲养模式及对先民肉食资源的贡献,尚缺乏足够的认识.为此,本文对陕西兴乐坊遗址出土动物与人骨开展了C、N稳定同位素分析,并对其中4个猪骨进行AMS-14C测年.同位素数据结果显示:野生动物(獐、青羊、梅花鹿)栖息于C3类的植被环境,家养动物(猪、狗)和人,则主要以C4类为食.3个猪个体的年代为5449~5300 cal.B.P.,而1个猪个体年代偏晚(4089~3985 cal.B.P.),其同位素数据也异于其他个体.结合该遗址的植物考古资料(粟和黍具有高的出土概率),认为:家养动物(猪和狗)饲喂了大量以粟类作物的副产品或者人类的残羹冷炙(粪便).根据食物链从生产者至消费者的同位素分馏效应(δ13 C值约富集1‰,δ15N值约富集3‰~5‰),比较了先民与野生动物以及家养动物的同位素数据,发现先民与猪的δ13 C和 δ15N值的差异最小(0.2‰和1.9‰),这反映了先民的肉食资源应主要源于家猪.家猪的饲养和管理,为庙底沟文化的快速发展奠定了深厚的物质和经济基础.此外,1例梅花鹿角具有偏正的δ13C值(-13.2‰),暗示发达的粟作农业还为先民尝试驯养其他野生动物(如鹿)提供了可能.  相似文献   

柴北缘大煤沟侏罗系泥质岩有机元素及碳同位素特征与古气候环境分析     

李温帅  张小莉  冯乔  焦科  陈琰  邹开真  崔涵 《高校地质学报》2020,26(6):704-711

柴北缘大煤沟地区侏罗系记录了西北地区古环境演化的重要信息。文章通过对大煤沟剖面进行有机地球化学分析,尝试恢复大煤沟地区侏罗系的环境演化。分析认为,H/C比与C/N比、δ ¹³Ｃ呈现良好的负相关性。早侏罗世：C/N比和δ ¹³Ｃ整体逐渐减小,H/C比逐渐变大;中侏罗世：C/N比和δ ¹³Ｃ在前期保持稳定,后期急剧负偏,而H/C比则反之;晚侏罗世：C/N比和δ ¹³Ｃ基本保持低值不变,H/C比稳定在高值区间。早—中侏罗世有机元素C/N比多大于15,表明有机质来源主要以 陆生高等植物为主。大煤沟剖面古气候表现为两个旋回,在早侏罗世小煤沟组时期古气候特征为温湿—干热,自中侏罗世晚期古气候开始从温湿向干热演化。  相似文献   

Standing stocks and production rates of phytoplankton and abundance of bacteria in the Seto Inland Sea, Japan     

Kuninao Tada  Koji Monaka  Masakazu Morishita  Toshiya Hashimoto 《Journal of Oceanography》1998,54(4):285-295

Standing stocks and production rates of phytoplankton and abundance of bacteria were investigated at 39 stations in the Seto Inland Sea, Japan during four crulses in October 1993, January, April and June 1994. Primary productivity was measured by the¹³C tracer method. Photosynthetic rate varied from 0.41 to 32.1 μgC/1/h with an average value of 4.67 μgC/l/h. Annual primary production was estimated to be 218 gC/m²/year. Annual primary production in this study was 1.8 times as high as the values which were previously reported at same area. The reason for the disagreement between our primary production value and previous values is not thought to be due to the difference of methods used for measuring primary production or the different Chl.a concentrations but to the method of estimating the primary production in the euphotic zone from thein vitro measurements. The distribution of bacterial cells in surface seawater was examined during the same cruises. Bacterial cell density ranged from 0.32 to 3.4×10⁶ cells/ml. The density was relatively high in the eutrophic regions of Hiroshima Bay and Osaka Bay In addition, a high density of bacteria was also observed in an area within Suo Nada where Chl.a was relatively low. The disparity between Chla and bacterial density in Suo Nada suggests that bacterial abundance can be controlled by the availability of substrates other than phytoplankton exudate.  相似文献