A New Plankton Sampler for Coral Reefs   总被引：1，自引：0，他引：1  

Klaus  Rutzler  Joan D.  Ferraris Ronald J.  Larson 《Marine Ecology》1980,1(1):65-71

Abstract. A new self-contained Horizontal Plankton Sampler (HOPLASA) collects near-reef plankton that is not captured by conventional net tows and emergence traps. An electrical motor-propeller assembly inside a large acrylic cylinder drives water past an in-line flowmeter and through a rigidly attached plankton net. When positioned in the coral reef environment this sampling gear filters known quantities of bottom water. Larvae and developmental stages of many invertebrates and some fishes that never migrate to upper water layers but constitute an important fraction of the food chain are captured. Larvae of sponges, corals, and gorgonians, the most important animal reef builders, are obtained live and undamaged and can be cultured in the laboratory for identification after metamorphosis.  相似文献   

The incidence and nature of bedload transport during flood flows in coarse-grained alluvial channels     

Ian Reid  Lynne E Frostick  John T Layman 《地球表面变化过程与地形》1985,10(1):33-44

A continuous record reveals that the incidence of bedload in a coarse-grained river channel changes from flood to flood. Long periods of inactivity encourage the channel bed to consolidate sufficiently so that bedload is largely confined to the recession limb of the next flood-wave. But when floods follow each other closely, the bed material is comparatively loose and offers less resistance to entrainment. In this case, substantial amounts of bedload are generated on the rising limb. This is confirmed by values of bed shear stress or stream power at the threshold of initial motion which can be up to five times the overall mean in the case of isolated floods or those which are the first of the season. This produces a complicated relationship between flow parameters and bedload and explains some of the difficulties in establishing bedload rating curves for coarse-grained channels. Besides this, the threshold of initial motion is shown to occur at levels of bed shear stress three times those at the thresholds of final motion. This adds further confusion to attempts at developing predictive bedload equations and clearly indicates at least one reason why equations currently in use are unsatisfactory. Bedload is shown to be characterized by a series of pulses with a mean periodicity of 1.7 hours. In the absence of migrating bedforms, it is speculated that this well-documented pattern reflects the passage of kinematic waves of particles in a slow-moving traction carpet. The general pattern of bedload, including pulsations, is shown to occur more or less synchronously at different points across the stream channel.  相似文献   

一种新型浅层井CO2监测系统的研发   总被引：2，自引：0，他引：2  

刘学浩  李琦  方志明  刘桂臻  宋然然  汪海滨  李小春 《岩土力学》2015,36(3):898-904

碳捕集、利用与封存（CCUS）能够有效降低传统能源产业CO2排放量,缓解气候变化。地层中CO2泄漏,作为潜在风险之一,可能改变浅层地下水水质,影响地表动植物生长,甚至危及周围人群安全。为监测CO2是否泄漏至地表并评估泄漏对浅层地下水的影响,进行浅层地下水连续取样十分必要,为此开发了一种新型浅层井CO2监测系统。详细介绍了该系统的构成、工作原理、技术难点应对措施和操作步骤。该系统基于U形管原理：渗入井筒的地下水通过单向阀进入U形管内,而后采用氮气对U形管的一端加压,U形管的另一端得到样品。该系统能连续对地下不同层位（层位数根据实际需求确定）进行取样,为封存现场环境风险预警系统提供组成数据。  相似文献   

A new method of snowmelt sampling for water stable isotopes   总被引：1，自引：0，他引：1       下载免费PDF全文

D. Penna  M. Ahmad  S. J. Birks  L. Bouchaou  M. Brenčič  S. Butt  L. Holko  G. Jeelani  D. E. Martínez  G. Melikadze  J. B. Shanley  S. A. Sokratov  T. Stadnyk  A. Sugimoto  P. Vreča 《水文研究》2014,28(22):5637-5644

We modified a passive capillary sampler (PCS) to collect snowmelt water for isotopic analysis. Past applications of PCSs have been to sample soil water, but the novel aspect of this study was the placement of the PCSs at the ground‐snowpack interface to collect snowmelt. We deployed arrays of PCSs at 11 sites in ten partner countries on five continents representing a range of climate and snow cover worldwide. The PCS reliably collected snowmelt at all sites and caused negligible evaporative fractionation effects in the samples. PCS is low‐cost, easy to install, and collects a representative integrated snowmelt sample throughout the melt season or at the melt event scale. Unlike snow cores, the PCS collects the water that would actually infiltrate the soil; thus, its isotopic composition is appropriate to use for tracing snowmelt water through the hydrologic cycle. The purpose of this Briefing is to show the potential advantages of PCSs and recommend guidelines for constructing and installing them based on our preliminary results from two snowmelt seasons. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

Testing a new sampler for measuring plot soil loss          下载免费PDF全文

Francesco G. Carollo  Costanza Di Stefano  Vito Ferro  Vincenzo Pampalone  Francesco Sanzone 《地球表面变化过程与地形》2016,41(7):867-874

In order to measure soil loss in equipped plots the estimate of the weight of solid material intercepted at their lower end is required. At the experimental area of Sparacia, Sicily, the runoff produced by an erosive event is collected within storage tanks with a capacity of about 1 m³. In this paper, the use of a new sampler is proposed to measure easily the weight of solid material eroded from an experimental plot and collected into a storage tank. The sampler is a cylinder having a closing valve at the bottom. Two different series of runs were carried out both to test the reliability of the sampler and to establish a sampling procedure, respectively. An analysis of various sampling configurations usable in the field differentiated by the number and location of sampling verticals in the tank cross‐section was finally carried out. The results of the present investigation are that the concentration measurement by the sampler was more accurate than that obtained by other methods involving a collection tank, agitation and sampling of the suspension. This sampler is cheap and usable in combination with a quick field sampling procedure which is particularly advisable when the number of plots equipped at an experimental area is large. The sampler was tested using a clay soil contained within cylinders and a cubic tank, but it appeared also to be usable with coarser sediment than clay and in combination with tanks having a different shape. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

旋风分离式集沙仪在风洞内集沙效率的试验研究   总被引：4，自引：2，他引：2  

赵满全  付丽宏  王金莲  冬梅 《中国沙漠》2009,29(6):1009-1014

为了改变旋风分离式集沙仪本体直径、入口截面宽度、锥体段高度的主要结构参数,在实验室风蚀风洞内分别进行了性能试验,测试了集沙仪的性能参数并进行了分析。结果表明,改变其中一个结构参数的水平,集沙仪平均沙尘收集率在80%~90%之间,而且参数水平的变化对于各粒径范围的土样的沙尘收集率影响程度不同。通过分析可得:在各风速下,对于各种粒径的土样,本体直径由50 mm改变为40 mm时沙尘收集率降低;入口截面宽度由10 mm变为8 mm时沙尘收集率提高约2%~3%;锥体段高度由100 mm改变为125 mm时沙尘收集率提高约3%~4%。对于不同粒径的土样,当分别以本体直径为50 mm、入口截面宽度为8 mm、锥体段高度为125 mm时,集沙仪的平均沙尘收集率提高2%~4%。  相似文献   

天然气水合物保真取心装置内部密封技术分析     

张凌  蒋国盛  宁伏龙  涂运中  吴翔  窦斌 《现代地质》2009,23(6):1147-1152

摘要：在海底天然气水合物地层钻探中,利用压力岩心取样器(PCS)获取保压岩心对于后续相关的处理和分析非常重要。首先回顾了国内保压保温取心器相关研究现状,然后从PCS取样腔内部球阀和O型圈等密封结构的特点分析了其内部上、下两部分的密封技术。在综合分析国内两种取样器密封结构特点的基础上,结合岩心现场处理与分析的特点,对PCS与上述两种取样器的密封技术进行了探讨,为取样器的密封设计、岩心现场压力和温度的保持以及保压岩心的保真转移提出了几点建议。  相似文献   

Benefits of design modifications to the Birkbeck bedload sampler illustrated by flash‐floods in an ephemeral gravel‐bed channel     

Nathaniel Bergman  Jonathan B. Laronne  Ian Reid 《地球表面变化过程与地形》2007,32(2):317-328

The benefits of three simple modifications to the design of a Birkbeck bedload slot‐sampling system that has been continuously operating in Nahal Eshtemoa, Israel, since the early 1990s are demonstrated. The modifications include the deployment of a removable slot cover which delays the accumulation of sediment, so allowing sampling at late stages of a flood and, in conjunction with other samplers, extending the period of sampling during a flood wave; inclusion of a slot the size of which is adjustable so that that the probability of sampling the largest clast sizes in transit as bedload can be increased post‐installation, once knowledge is gained about the bedload grain‐size distribution; and a sampler side‐wall door that allows stratification and textural changes within the accumulated bedload to be identified, so promoting intelligent sampling of the deposit for grain‐size determination. Results from seven flash‐floods are presented and discussed, with recommendations for bedload monitoring, particularly in rivers where sediment flux is high and dynamic sediment records are inevitably short because of instrumental limitations. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   

Mark4格式器升级为Mark5B采样器的方法及步骤     

杨文军 《云南天文台台刊》2012,(1):26-33

近年来世界VLBI（Very Large Baseline Interferometry）终端技术发展迅速,主流的记录终端已发展到Mark5B记录系统,Mark5C也正在研制和测试阶段。为了适应未来高速率、海量数据以及数字基带转换器观测的要求,需要将现有的Mark5A升级到Mark5B或Mark5B＋,相应地需要将Mark4格式器升级为MarkB采样器。主要描述了相关设备的原理以及Mark4格式器升级的步骤。  相似文献   

Measurement of shipwreck-derived waterborne trace metals using DGT samplers     

T Dempsey  A Hartland  C McSweeney  CN Battershill 《新西兰海洋与淡水研究杂志》2016,50(1):115-130

ABSTRACT

A contemporary approach to the assessment of metal pollutants in aquatic environments has been to measure contaminant concentrations in biological indicator species (mussels, oysters). However, for environments in which such indicator species do not occur naturally and cannot be deployed, alternative approaches for monitoring trace-metal pollution are required. Three years after the 2011 grounding of the MV Rena, diffusive gradients in thin films (DGT) samplers were deployed at Otaiti (the offshore reef where the Rena grounded) to assess levels of waterborne trace-metal contamination. Although the probability of detecting waterborne contaminants within a dynamic open ocean reef environment would seem low, due to mixing and dilution, our analyses confirmed the presence of copper (≤0.43 vs ≤0.27?nmol?kg^?1), iron (≤6.3 vs ≤4.2?nmol?kg^?1), aluminium (≤8.9 vs ≤1.3?nmol?kg^?1), zinc (≤2.8 vs ≤2.0?nmol?kg^?1) and manganese (≤0.11 vs ≤0.09?nmol?kg^?1) at elevated concentrations in the Rena debris field relative to reference sites. The results demonstrate the utility of DGTs as a tool for measuring waterborne contaminants and suggest further research is required to characterise the contaminant plume and determine what effect it might have on the recovery of Otaiti's impacted biological communities.  相似文献