监理在第二次全国土地调查中的作用     

冀耀宇  唐立哲  常美 《测绘与空间地理信息》2011,34(3):226-227,230

着重论述了第二次全国土地调查工作中项目监理的职责、质量保障措施及实施.通过论述说明第二次全国土地调查工作引入项目监理机制的必要性和作用.  相似文献   

Chemosynthetic trophic support for the benthic community at an intertidal cold seep site at Mocha Island off central Chile     

Javier Sellanes  Germán Zapata-Hernández  Silvio Pantoja  Gerdhard L. Jessen 《Estuarine, Coastal and Shelf Science》2011

We analyzed C and N stable isotope ratios of benthic fauna and their potential food sources at an intertidal methane seep site and a control site without emanation at Mocha Island (central Chile). The objective was to trace the origin of the main food sources used by the local heterotrophic fauna, based on the hypothesis that chemosynthetic production could be partially fueling the local food web at the seep site. Food sources sampled at both sites included macroalgae, particulate organic matter and bacteria-like filaments found growing over the red algae Gelidium lingulatum within the areas of active methane release.  相似文献   

Origin of resources and trophic pathways in a large SW Atlantic estuary: An evaluation using stable isotopes     

Florencia Botto  Esteban Gaitán  Hermes Mianzan  Marcelo Acha  Diego Giberto  Agustín Schiariti  Oscar Iribarne 《Estuarine, Coastal and Shelf Science》2011

The Río de la Plata (34° 36′ S, 55° 58′ W; Argentina and Uruguay) estuary, one of the most important South American estuarine environments, is characterized by weak seasonal freshwater discharge, low tidal amplitude (<1 m), a wide and permanent connection to the sea, and a salt-wedge regime. Using stable isotope analysis, we explored the relative importance of the different sources of primary production in the food web. Our results show that phytoplankton and macrodetritus from terrestrial salt and freshwater marshes both contribute to the food web of the Río de la Plata estuary. On the basis of the sampled species, we identified four trophic levels. The clam Mactra isabelleana, the calanoid copepod Acartia tonsa, and the opossum shrimp Neomysis americana are the primary consumers. The rays Atlantoraja castelnaui and Squatina guggenheim and the shark Galeorhinus galeus are the top predators. The Río de la Plata food web shows an important input of nutrients derived from phytoplankton. Rays, sharks, and predatory gastropods reveal an important contribution of C4 plants (likely Spartina spp.). However, production derived from C3 plants is also important for some species. The fishes Brazilian menhaden, Brevoortia aurea; the stripped weakfish Cynoscion guatucupa; and the whitemouth croaker, Micropogonias furnieri, showed differences in their isotopic signatures as juveniles and adults, indicating different food sources, and they were therefore treated as different components of the food web. Our data suggest that detritus from salt and freshwater marshes is reaching the Río de la Plata estuary and can be an important allocthonous source of energy to this environment.  相似文献   

Feeding strategies of deep-sea sub-Arctic macrofauna of the Faroe-Shetland Channel: Combining natural stable isotopes and enrichment techniques     

E. Gontikaki  D.J. MayorB.E. Narayanaswamy  U. Witte 《Deep Sea Research Part I: Oceanographic Research Papers》2011,58(2):160-172

The response of a sub-arctic, deep-sea macrofaunal community to a simulated food sedimentation event was studied by means of a stable isotope “pulse-chase” experiment. A food pulse was simulated by adding 500 mg C m⁻² of ¹³C-labelled diatoms, Chaetoceros radicans, to sediment cores retrieved from 1080 m in the Faroe-Shetland Channel. Carbon uptake by specific macrofaunal groups was quantified after 3 and 6 days of incubation. The carbon uptake of the dominant taxon (Polychaeta) was quantified at the genus-, and where possible, species-level, representing a data resolution that is rare in deep-sea tracer studies. The macrofaunal community reacted rapidly to the diatom addition, with 47% and 70% of the animals illustrating ¹³C-enrichment after 3 and 6 days, respectively. Approximately 95% of C uptake was located in the upper 2 cm due to the particularly shallow vertical distribution of the macrofaunal community and the nonexistent tracer subduction by burrowing species. Polychaetes of the families Ampharetidae and Cirratulidae were among the most heavily labelled with above background enrichment reaching 1300‰. Approximately 0.8 and 2.0 mg C m⁻² were processed by the macrofauna after 3 and 6 days, representing 0.2% and 0.4% of the added carbon, respectively. It was not possible to differentiate sub-surface deposit-feeding polychaetes from predator/scavenger- and omnivorous polychaetes using their natural ??¹⁵N signatures. However, the combination of natural abundance ??¹⁵N data and ¹³C-labelling experiments proved to be useful for elucidating trophic relations in deep-sea food webs. This study confirms that macrofauna play an active role in the short-term carbon cycling at bathyal depths even at sub-zero temperatures and highlights the need for detailed knowledge of the community structure in understanding carbon processing patterns and early diagenesis of organic matter in marine sediments.  相似文献   

基于WebServices的空间信息应用集成解决方案研究     

邬群勇  王钦敏 《地球信息科学学报》2011,13(2):219-225

 在对应用集成及其发展分析的基础上,将Web Services技术运用到空间信息应用集成,提出和建立了面向服务的空间信息应用集成框架,包括Web应用层、服务集成层、服务层和UDDI等4个组成部分。通过该框架,可以实现空间信息集成、服务集成和应用集成。论文解决了空间信息应用集成框架中的2个关键问题:(1)提出了分别从数据层次和业务层次对原有系统集成的解决方案,在数据层次上,提出了基于XML/GML的空间数据封装和基于Web服务接口的空间数据封装策略;在业务层次上,提出根据系统的功能模块和业务逻辑分别进行封装的策略;(2)提出了空间信息Web服务链接和服务组合的串联、并联和混联模式,通过三种模式服务链的设计,可以实现多个服务的链接和组合,从而完成空间信息以及应用集成。  相似文献   

电磁成像正演仿真与传感器参数优化设计   总被引：1，自引：0，他引：1       下载免费PDF全文

王滨涛  吴锡令  王晓星 《地球物理学报》2009,52(12):3142-3146

应用有限元方法对电磁层析成像测量进行正演模拟,计算不同测量组合下各种典型流型的电势实部和虚部分布,考察电极个数、电极张角以及电极厚度对模拟测量响应的影响,并采用神经网络方法对传感器各结构参数进行优化设计.研究结果表明,介质分布对电势影响起主要作用,其中虚部分布特征更加明显;传感器各参数中电极数目对测量值影响较大,电极张角和电极厚度有一定影响.  相似文献   

Seasonal variation of microzooplankton (20–200 μm) and its possible implications on the vertical carbon flux in the western Bay of Bengal     

R. Jyothibabu  N.V. Madhu  P.A. Maheswaran  K.V. Jayalakshmy  K.K.C. Nair  C.T. Achuthankutty 《Continental Shelf Research》2008

Stratification (throughout the year) and low solar radiation (during monsoon periods) have caused low chlorophyll a and primary production (seasonal average 13–18 mg m⁻² and 242–265 mg C m⁻² d⁻¹, respectively) in the western Bay of Bengal (BoB). The microzooplankton (MZP) community of BoB was numerically dominated by heterotrophic dinoflagellates (HDS) followed by ciliates (CTS). The highest MZP abundance (average 665±226×10⁴ m⁻²), biomass (average 260±145 mg C m⁻²) and species diversity (Shannon weaver index 2.8±0.42 for CTS and 2.6±0.35 for HDS) have occurred during the spring intermonsoon (SIM). This might be due to high abundance of smaller phytoplankton in the western BoB during SIM as a consequence of intense stratification and nitrate limitation (nitracline at 60 m depth). The strong stratification during SIM was biologically evidenced by intense blooms of Trichodesmium erythraeum and frequent Synechococcus–HDS associations. The high abundance of smaller phytoplankton favors microbial food webs where photosynthetic carbon is channeled to higher trophic levels through MZP. This causes less efficient transfer of primary organic carbon to higher trophic levels than through the traditional food web. The microbial food web dominant in the western BoB during SIM might be responsible for the lowest mesozooplankton biomass observed (average 223 mg C m⁻²). The long residence time of the organic carbon in the surface waters due to the active herbivorous pathways of the microbial food web could be a causative factor for the low vertical flux of biogenic carbon during SIM.  相似文献   

In situ heavy metals (copper, lead and cadmium) in different plankton compartments and suspended particulate matter in two coupled Mediterranean coastal ecosystems (Toulon Bay, France)     

Rossi N  Jamet JL 《Marine pollution bulletin》2008,56(11):1862-1870

We monitored the concentrations of copper, lead and cadmium in seawater, in suspended particulate matter (SPM) and in bacteria, phyto- and zooplankton communities separated from abiogenic particles, over a one year cycle in two coupled Mediterranean coastal ecosystems (Little Bay (LiB) and Large Bay (LaB)). Metals were present in seawater in the order Cu > Pb > Cd in both bays and showed important variations within the same month than among months. In LiB, their concentrations were between 0.62 and 2.82 μg Cu l⁻¹, 0.16 and 19 μg Pb l⁻¹ and 0.007 and 0.14 μg Cd l⁻¹, respectively, whereas in LaB, they were between 0.23 and 2.11 μg Cu l⁻¹, 0.09 and 0.76 μg Pb l⁻¹ and not detected and 0.65 μg Cd l⁻¹. SPM play an important role on metal adsorption, especially for copper. Bioaccumulation factors showed that bacteria and phytoplankton accumulate metals whereas zooplankton tends to biodiminish them in the plankton food web.  相似文献   

Local dynamical equivalence of certain food webs     

Thilo Gross  Ulrike Feudel 《Ocean Dynamics》2009,59(2):417-427

An important challenge in theoretical ecology is to find good coarse-grained representations of complex food webs. Here, we use the approach of generalized modeling to show that it may be possible to formulate a coarse-graining algorithm that conserves the local dynamics of the model exactly. We show examples of food webs with a different number of species that have exactly identical local bifurcation diagrams. Based on these observations, we formulate a conjecture governing which populations of complex food webs can be grouped together into a single variable without changing the local dynamics. As an illustration, we use this conjecture to show that chaotic regions generically exist in the parameter space of a class of food webs with more than three trophic levels. While our conjecture is at present only applicable to relatively special cases, we believe that its applicability could be greatly extended if a more sophisticated mapping of parameters were used in the model reduction.  相似文献   

潍坊潍河大桥水上钻探平台设计     

刘宗林 《地质与勘探》2000,36(3):95-95

介绍了潍坊潍河大桥水上钻探平台的设计、使用和效果  相似文献