Coastal Massachusetts pond development: edaphic,climatic, and sea level impacts since deglaciation     

Marjorie Green Winkler  Patricia R. Sanford 《Journal of Paleolimnology》1995,14(3):311-336

Kettle ponds in the Cape Cod National Seashore in southeastern Massachusetts differ in their evolution due to depth of the original ice block, the clay content of outwash in their drainage basins, and their siting in relation to geomorphic changes caused by sea-level rise, barrier beach formation, and saltmarsh development. Stratigraphic records of microfossil, carbon isotope, and sediment changes also document late-glacial and Holocene climatic changes.The ponds are separated into 3 groups, each of which follow different development scenarios. Group I ponds date from the late-glacial. They formed in clay-rich outwash, have perched aquifers and continuous lake sediment deposition. The earliest pollen and macrofossil assemblages in Group I pond sediments suggest tundra and spruce-willow parklands before 12 000 yr B.P., boreal forest between 12 000 and 10 500 yr B.P., bog/heath initiation and expansion during the Younger Dryas between 11 000 and 10 000 yr B.P., northern conifer forest between 10 500 and 9500 yr B.P., and establishment of the Cape oak and pitch pine barrens vegetation after 9500 yr B.P. Sedimentation rate changes suggest lowered freshwater levels between 9000 and 5000 yr B.P. caused by decreased precipitation on the Atlantic Coastal Plain. Lake sediment deposition began in the middle Holocene in Group II ponds which formed in clay-poor outwash. These ponds date from about 6000-5000 yr B.P. In these ponds sediment deposition began as sea level rose and the freshwater lens intersected the dry basins. The basal radiocarbon dates of these ponds and stable carbon isotope analyses of the pond sediments suggest a sea-level curve for Cape Cod Bay. Holocene topographic changes in upland and the landscape surrounding the ponds is reconstructed for this coastal area.Group III ponds in the late Holocene landscape of the Provincelands dunes originated as interdunal bogs about 1000 yr B.P. and became ponds more recently as water-levels increased. Peat formation in the Provincelands reflects climatic changes evident on both sides of the Atlantic region.This is the 8th in a series of papers published in this special AMQUA issue. These papers were presented at the 1994 meeting of the American Quaternary Association held 19–22 June, 1994, at the University of Minnesota, Minneapolis, Minnesota, USA. Dr Linda C. K. Shane served as guest editor for these papers.  相似文献   

Seismo-tectonic divisions of strong earthquakes with M_s≥7.0 and their tectonic geomorphology along Xianshuihe-Xiaojiang fault zone     

张世民  谢富仁 《地震学报(英文版)》2001,(1)

IntroductionXianshuihe-Xiaojiang fault zone is an important active fault zone and a strong earthquake belt in the southeastern margin of Qinghai-Tibet Plateau (Figure 1). Since 814 AD a total of 14 earthquakes with M ( 7, including one of magnitude 8.0, took place there. This large-scale fault zone runs from north to south, includes the northwesterly Xianshuihe fault, the near-NS An(ninghe fault, NNW Zemuhe fault, and near-NS Xiaojiang fault. It forms the east boundary of Sichuan-Yunn…  相似文献   

Seismo-tectonic divisions of strong earthquakes with M _S≥7.0 and their tectonic geomorphology along Xianshuihe-Xiaojiang fault zone     

Zhang Shi-min  Xie Fu-ren 《地震学报(英文版)》2001,14(1):38-48

Seismo-tectonic areas of historical strong earthquakes with M _S≥7 along Xianshuihe-Xiaojiang fault zone are divided, and their individual fault-pattern and tectonic geomorphology are analyzed. Those strong-earthquake areas are located in some special parts of the fault zone, where the major branch-faults of the fault zone form left stepping, parallel, and fork-like patterns. In the strong-earthquake areas structurally complicated basins are developed, such as pull-apart basins in fork-like area, in double stepping area, and in stepping and fork-like areas. Foundation item: Chinese Joint Seismological Science Foundation (9507424). Contribution No. 2001A003, Institute of Crustal Dynamics, China Seismological Bureau.  相似文献   

郴州华塘煤矿采空区地面塌陷的影响因素及防治措施探讨   总被引：1，自引：0，他引：1  

李守贤  陈荣华  申俊 《地质灾害与环境保护》2007,18(3):19-22

郴州华塘煤矿采空区地面塌陷的影响因素是采矿方法、煤层特征(厚度、产状和埋深)、顶板岩石力学性质、地表水和地下水综合作用的结果.采矿方法的改进和煤柱的留设与保护是防治塌陷的主要措施,监测工作是不可缺少的重要手段.  相似文献   

基于BGM的不同繁殖长度对集合预报的影响          下载免费PDF全文

于永锋  张立凤 《应用气象学报》2007,18(1):86-93

利用T63L9全球谱模式和NCEP/NCAR再分析资料, 对BGM方法中增长模的繁殖长度对集合预报效果的影响进行研究。结果表明:与控制预报相比, 不同繁殖长度的集合预报都能使预报效果得到一定程度的改进, 特别是第4天预报以后, 改进程度随预报时效而稳步提高。三组不同繁殖长度的集合预报对控制预报的改进存在差别, 分析结果表明:繁殖长度为2 d的集合预报明显效果最差, 而繁殖3 d和4 d的集合预报差别并不明显。对集合Talagrand分布以及离散度的初步分析表明, 繁殖长度取为3 d似乎最为合理。  相似文献   

室外大池马氏珠母贝育苗试验     

何水养  陈明耀  黄卓华 《广东海洋大学学报》1990,(1)

本试验利用一个室外露天水容量为187立方米的水泥池进行马氏珠母贝人工育苗,一次育出贝苗5065万只,平均每立方米水体收贝苗27.08万只。室外大池育苗具有耗饵量少,节约人力,培育的幼虫和贝苗生长快和产苗量大等优点,能够迅速提高贝苗总产量,解决目前存在的贝苗(?)足的困难,值得提倡推广。  相似文献   

生物膜“细菌-藻类”协同系统改良淡水池塘养殖水质与沉积物的效果研究     

江兴龙  邓来富 《海洋与湖沼》2015,46(3):603-610

采用池塘中设置生物膜净水栅对比实验的方法,在8口土池开展生物膜"细菌-藻类"协同系统改良池塘养殖水质与沉积物的效果、对苗种培育效果的影响及其相关机理等的研究。结果表明,在142d的养殖期间,处理组比对照组节水减排达65.1%,具有极显著差异(P0.01);处理组水质的p H、总氮和亚硝酸盐氮分别极显著低于对照组3.7%、31.3%和38.7%(P0.01),氨氮、总磷、活性磷和硫化物分别显著低于对照组25.6%、41.6%、37.8%和27.9%(P0.05);弧菌数和藻类密度极显著低于对照组63.1%和51.3%,硅藻相对密度极显著高于对照组93.7%;细菌总数显著高于对照组50.8%,蓝藻相对密度显著低于对照组16.6%;处理组的藻类生物均匀度指数显著高于对照组8.9%;生物膜上的细菌总数高达1.30×109 CFU/g,而弧菌数为零;处理组池塘沉积物的氧化还原电位显著高于对照组30.5%,硫化物浓度显著低于对照组47.0%;草鱼苗种起捕规格、成活率、产量和生长速度分别显著高于对照组24.6%、4.3%、29.8%和28.6%,饲料系数极显著低于对照组15.6%,处理组每公顷池塘培育草鱼大规格鱼种可增加净利润约1.92万元。  相似文献   

黄鳍东方鲀人工育苗技术及胚胎、仔稚幼鱼发育特征研究     

钟建兴  刘波  郑惠东  李雷斌  钟晨辉 《海洋科学》2015,39(7):43-51

为开展黄鳍东方鲀(Fugu xanthopterus)批量全人工育苗、胚胎及仔稚幼鱼发育特征研究, 作者使用地欧酮(DOM)、促黄体释放激素类似物(LRH)及绒毛膜促性腺激素(HCG)对性成熟黄鳍东方鲀进行人工催产。结果表明黄鳍东方鲀亲鱼效应时间为39～60h, 获产率为55.0%～92.5%; 卵受精率为35.5%～84.7%, 3 年产卵7 400 g; 受精卵在海水水温17.0～23.2℃、盐度21～30、pH8.0～8.2 人工条件下孵化, 孵化率为33.6%～91.7%, 孵出仔鱼499 万尾; 2005 年、2006 年经前期培育, 共培育出黄鳍东方鲀后期仔鱼394.5 万尾, 成活率为68.2%～94.3%; 室内水泥池后期培育出平均全长2.6 cm±0.2 cm 幼鱼3100 尾, 成活率为15.5%; 池塘生态培育出平均全长3.7 cm±0.5 cm 幼鱼53.3 万尾, 成活率为11.2%～13.8%。黄鳍东方鲀受精卵为沉性黏性卵, 近椭球形, 乳白色, 卵膜厚且不透明, 卵径0.9～1.0mm,在海水水温18.2～22.2℃条件下, 3 h 分裂为2 细胞; 3 h 20 min 4 细胞; 3 h 45 min 8 细胞; 10 h 10 min 多细胞; 17 h 30 min 囊胚出现; 28 h 原肠期; 57 h 15 min 胚体形成期; 69 h 20 min 心跳出现; 130 h 50 min出膜期; 144 h 孵出仔鱼。初孵仔鱼全长2.2～2.4 mm, 体圆而粗短, 尾部细长、透明; 孵出后第20 天, 胸鳍、臀鳍、背鳍基本形成, 进入稚鱼期; 孵出后第45 天, 上下颌门齿发达, 各鳍发育完整, 小刺基本形成, 进入幼鱼期。  相似文献   

海黍子(Sargassum muticum)池塘养殖及对氮磷去除效果的研究     

王翔宇  王志刚  吴海一 《海洋湖沼通报》2015,(1):91-95

初步研究了在海参养殖池塘中,不同养殖方式下,大型海藻海黍子(Sargassum muticum)的生长特性及对水体中氨氮和活性磷的去除作用。2012年3~5月,在山东莱州试验养殖海黍子60d,结果发现其长度最大从43.8cm增长到81.3cm,增长85.6%,日增长率(SGR)在14℃时最大,达到5.0%;每绳的平均质量从0.74kg增到2.59kg,增长3.5倍,SGR在12℃时最大,达4.3%;水体氨氮平均下降了25.9%,活性磷下降了37.5%。实验证明海黍子能在适合的池塘中养殖,并且能有效的去除水体中的氨氮和活性磷,是有效的近海生境修复大型工具种海藻。  相似文献   

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张华  蒋海昆  姚宏  周斌  郭培兰  阎春恒  文翔 《大地测量与地球动力学》2014,34(4):88-91

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