Effect of Ocean Climate Changes on the Korean Stock of Pacific Saury, <Emphasis Type="Italic">Cololabis saira</Emphasis> (BREVOORT)     

Chang?Ik?ZhangEmail author  Yeong?Gong 《Journal of Oceanography》2005,61(2):313-325

Atmospheric, hydrographic and fishery biological factors indicated that the abnormal northward shift in the distribution of Pacific saury might be the result of a strong flux of warm water into the Japan/East Sea in the late 1970s. Recruitment failure of saury in the late 1970s was attributed to the limitation of the productive area for primary production caused by oligotrophic warm water, and to mismatch of the time of the spring outburst with the earlier arrival of saury to the feeding ground. Comparison of monthly upper mixed layer depth (MLD) and critical depth supported the possibility of the mismatch phenomenon. However, an appropriate management scheme should be implemented to prevent recruitment overfishing for the stock when any sign of ocean climate changes is detected.  相似文献   

Facies architecture of the mixed carbonate/siliciclastic inner continental shelf of west-central Florida: implications for Holocene barrier development   总被引：2，自引：0，他引：2  

Gregg R. Brooks  Larry J. Doyle  Beau C. Suthard  Stan D. Locker  Albert C. Hine   《Marine Geology》2003,200(1-4):325-349

Sediment vibracores and surface samples were collected from the mixed carbonate/siliciclastic inner shelf of west–central Florida in an effort to determine the three-dimensional facies architecture and Holocene geologic development of the coastal barrier-island and adjacent shallow marine environments. The unconsolidated sediment veneer is thin (generally <3 m), with a patchy distribution. Nine facies are identified representing Miocene platform deposits (limestone gravel and blue–green clay facies), Pleistocene restricted marine deposits (lime mud facies), and Holocene back-barrier (organic muddy sand, olive-gray mud, and muddy sand facies) and open marine (well-sorted quartz sand, shelly sand, and black sand facies) deposits. Holocene back-barrier facies are separated from overlying open marine facies by a ravinement surface formed during the late Holocene rise in sea level. Facies associations are naturally divided into four discrete types. The pattern of distribution and ages of facies suggest that barrier islands developed approximately 8200 yr BP and in excess of 20 km seaward of the present coastline in the north, and more recently and nearer to their present position in the south. No barrier-island development prior to approximately 8200 yr BP is indicated. Initiation of barrier-island development is most likely due to a slowing in the Holocene sea-level rise ca. 8000 yr BP, coupled with the intersection of the coast with quartz sand deposits formed during Pleistocene sea-level highstands. This study is an example of a mixed carbonate/siliciclastic shallow marine depositional system that is tightly constrained in both time and sea-level position. It provides a useful analog for the study of other, similar depositional systems in both the modern and ancient rock record.  相似文献   

Determining species composition in mixed-species marks: an example from the New Zealand hoki (Macruronus novaezelandiae) fishery     

O'Driscoll  Richard L 《ICES Journal of Marine Science》2003,60(3):609-616

  相似文献   

分潮波模型多资料数值计算方法研究　Ⅲ.混合边值方法     

孙文心  潘文波 《中国海洋大学学报(自然科学版)》1996,(2)

将岸边划分为点、线两种类型边界，并相应给以观测潮位和法向流为零的不同边界条件，建立了ArakawaE网格中的分潮波方程的一种适定的数值计算方法，并对渤海四大分潮进行了试算。结果证明该方法在目前已知的这一类研究系列中是最为理想的方法。  相似文献   

Stratigraphic framework of sediment-starved sand ridges on a mixed siliciclastic/carbonate inner shelf; west-central Florida   总被引：1，自引：0，他引：1  

J. H. Edwards  S. E. Harrison  S. D. Locker  A. C. Hine  D. C. Twichell   《Marine Geology》2003,200(1-4):195-217

Seismic reflection profiles and vibracores have revealed that an inner shelf, sand-ridge field has developed over the past few thousand years situated on an elevated, broad bedrock terrace. This terrace extends seaward of a major headland associated with the modern barrier-island coastline of west-central Florida. The overall geologic setting is a low-energy, sediment-starved, mixed siliciclastic/carbonate inner continental shelf supporting a thin sedimentary veneer. This veneer is arranged in a series of subparallel, shore-oblique, and to a minor extent, shore-parallel sand ridges. Seven major facies are present beneath the ridges, including a basal Neogene limestone gravel facies and a blue-green clay facies indicative of dominantly authigenic sedimentation. A major sequence boundary separates these older units from Holocene age, organic-rich mud facies (marsh), which grades upward into a muddy sand facies (lagoon or shallow open shelf/seagrass meadows). Cores reveal that the muddy shelf facies is either in sharp contact or grades upward into a shelly sand facies (ravinement or sudden termination of seagrass meadows). The shelly sand facies grades upward to a mixed siliciclastic/carbonate facies, which forms the sand ridges themselves. This mixed siliciclastic/carbonate facies differs from the sediment on the beach and shoreface, suggesting insignificant sediment exchange between the offshore ridges and the modern coastline. Additionally, the lack of early Holocene, pre-ridge facies in the troughs between the ridges suggests that the ridges themselves do not migrate laterally extensively. Radiocarbon dating has indicated that these sand ridges can form relatively quickly (1.3 ka) on relatively low-energy inner shelves once open-marine conditions are available, and that frequent, high-energy, storm-dominated conditions are not necessarily required. We suggest that the two inner shelf depositional models presented (open-shelf vs. migrating barrier-island) may have co-existed spatially and/or temporally to explain the distribution of facies and vertical facies contacts.  相似文献   

地下水不稳定混合抽水的模型及模拟方法   总被引：2，自引：0，他引：2  

陈崇希 《地球学报》1996,17(Z1):222-228

本文指出在混合井抽水量已知的情况下,不能预先分配各层的分流量,只能从刻画混合抽水的模型运转中获取。提出“窜流”是混合井孔的最基本特征,建立了符合混合抽水机理的渗流-管流耦合模型.文中提出“折算（层流）渗透系数K1”的概念及其表达式,解决了管流与渗流耦合的困难,并提出了混合井井流的模拟方法。  相似文献   

对混合土液塑限试验的讨论     

刘福臣  孙玉琢  王启田 《岩土工程技术》2007,21(3):122-122,133

土的液塑限试验是土工试验常见试验之一。含有一定数量粗粒组的混合土,用0.5 mm以下粒径范围的土作液塑限试验,得到的液塑限偏低,由此土的分类定名不符合实际。建议用0.075 mm以下粒径范围的土做液塑限试验。  相似文献   

地下水中元素存在形式分析及其在水质评价中应用   总被引：1，自引：0，他引：1  

刘心彪 《地下水》2007,29(3):17-19

针对目前国内水质常规分析特点和水质评价的现状,运用热力学原理和质量守恒定律,结合实例,确定了地下水中元素以配位化合物的存在形式,并对各种配位化合物的组分进行了计算,这对水质评价有重要的价值,特别对一些有毒元素的评价更有实际意义.  相似文献   

CO_2 flux evaluation over the evergreen coniferous and broad-leaved mixed forest in Dinghushan, China     

《中国科学D辑(英文版)》2006,(Z2)

The Dinghushan flux observation site, as one of the four forest sites of ChinaFLUX, aims to acquire long-term measurements of CO2 flux over a typical southern subtropical evergreen coniferous and broad-leaved mixed forest ecosystem using the open path eddy covariance method. Based on two years of data from 2003 to 2004, the characteristics of temporal variation in CO2 flux and its response to environmental factors in the forest ecosystem are analyzed. Provided two-dimensional coordinate rotation, WPL correction and quality control, poor energy-balance and underestimation of ecosystem respiration during nighttime implied that there could be a CO2 leak during the nighttime at the site. Using daytime (PAR > 1.0μmol-1·m-2·s-1) flux data during windy conditions (u* > 0.2 m·s-1), monthly ecosystem respiration (Reco) was derived through the Michaelis-Menten equation modeling the relationship between net ecosystem CO2 exchange (NEE) and photosynthetically active radiation (PAR). Exponential function was employed to describe the relationship between Reco and soil temperature at 5 cm depth (Ts05), then Reco of both daytime and nighttime was calculated respectively by the function. The major results are: (i) Derived from the Michaelis-Menten equation, the apparent quantum yield (α) was 0.0027±0.0011 mgCO2·μmol-1 photons, and the maximum photosynthetic assimilation rate (Amax) was 1.102±0.288 mgCO2·m-2·s-1. Indistinctive seasonal variation of o or Amax was consistent with weak seasonal dynamics of leaf area index (LAI) in such a lower subtropical evergreen mixed forest. (ii) Monthly accumulated Reco was estimated as 95.3±21.1 gC·m-2 mon-1, accounting for about 68% of the gross primary product (GPP). Monthly accumulated NEE was estimated as -43.2±29.6 gC·m-2·mon-1. The forest ecosystem acted as carbon sink all year round without any seasonal carbon efflux period. Annual NEE of 2003 and 2004 was estimated as -563.0 and -441.2 gC·m-2·a-1 respectively, accounting for about 32% of GPP.  相似文献   

DISTRIBUTIONS AND VARIATIONS OF SURFACE OZONE IN CHANGSHU, YANGTZE DELTA REGION^*          下载免费PDF全文

YAN Peng  WANG Mulin  CHENG Hongbing  ZHOU Xiuji 《Acta Meteorologica Sinica》2003,17(2):205-217

Through one and half year continuous in-situ measurements,the distributions and variations of surface ozone and its precursors at a typical mixed agricultural and metropolitan area-Changshu,Yangtze Delta region,were studied.The preliminary analysis on the concentration levels and variations of surface ozone indicated the obvious seasonal and diurnal cycles during the experiment.The hourly averaged concentrations of surface ozone were high,in about 17% of total valid hours the surface ozone concentration exceeded 50 ppb,and in 22 days the hourly averaged ozone concentration was greater than 100 ppb.There were about 40% of the days in that the daily maximum 8-hour ozone concentration was greater than 50 ppb.The days with daily maximum 8-hour ozone concentration greater than 80 ppb were about 33 days that accounted for about 8% of the observational days.The variations of 5-day moving averaged ozone concentrations depended both on the weather conditions and on the changes of ozone in background atmosphere.Photochemical process had the significant impacts on ozone productions.  相似文献