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1.
H. E. Wright Jr. 《Journal of Paleolimnology》1991,6(1):37-49
This commentary is intended as a practical guide for the non-motorized use of piston corers to obtain undisturbed sections of lake sediments. Good recovery is essential for accurate reconstruction of environmental and limnological history. Emphasis is placed on the square-rod piston corer, which is widely used for acquisition of sediment cores in meter-long sections from lakes as much as 30 m deep. Coring platforms for open water can be easily prepared on pairs of boats or canoes or (in water depth up to 15 m) even a single small rubber raft, but firm anchoring is essenial to maintain the vertical position of the casing and to assure re-entry into a single hole. Incomplete recovery on individual drives is not a result of sediment compaction but rather the build-up of friction on the tube interior, by which the core forms a plug that prevents further recovery.Short cores of soft sediment for the study of recent changes in lakes are also best acquired with a piston corer, for a gravity corer without a piston may be subject to the same type of plug formation. In cases in which the structure of the sediment must be preserved (e.g. annual laminations), freezing the sediment in place with a dry-ice solution is the best procedure. 相似文献
2.
Unconsolidated, flocculent sediments that are frequently resuspended by wind action are found in many shallow-water lakes. Collecting sediment/water interface cores in such lakes for paleolimnological study may be problematic because it is difficult to determine the depth to the water/sediment interface. Accurately determining this water depth is necessary to guarantee that a piston corer does not penetrate the sediments prior to the drive and to maximize the core length. A simple instrument constructed with inexpensive, readily available components is described. This infrared floc detector (IFD) is used to sense the increased optical density of unconsolidated sediments as the detector is lowered into a lake. The IFD, in effect, yields a precise as well as an accurate measure of water depth. The depth to the water/sediment interface can be measured with an accuracy of approximately 1 cm, provided surface waters are relatively calm. 相似文献
3.
J. F. Boyle 《Journal of Paleolimnology》1995,13(1):85-87
A simple and reliable corer closure mechanism is described, which has three principal advantages over published designs for similar automatic gravity corers. First, it allows the use of large diameter tubes (at least 80 mm internal diameter), reducing core shortening effects. Second, it allows free passage of water during descent minimising bow wave effects. Third, it is compact enough for convenient use through seasonal ice cover. 相似文献
4.
A rod-less piston corer for lake sediments; an improved, rope-operated percussion corer 总被引：2，自引：0，他引：2
A lightweight, percussion corer, suitable for use in remote lakes of moderate depth, is described. The operation of the corer and suggestions for securing and transporting long sediment cores are presented. In particular, the design and use of a recovery pot, which allows the retrieval of undisturbed cores from sediments of unknown depth, is detailed. 相似文献
5.
A wide variety of scientific disciplines require representative samples of benthic sediment. As a result, a large range of sampling devices have been developed, each best suited to a particular set of conditions. However, all sediment sampling devices have inherent design problems that affect the degree to which samples represent the intact sediment. These issues are summarised, and a new corer design (the LOG corer) is presented and discussed. The LOG corer is a remotely-operated light-weight gravity corer suitable for obtaining relatively undisturbed short sediment cores in soft lacustrine sediments. 相似文献
6.
Freezing of sediment in situ at the lake bottom using a freeze corer has become an important method for taking samples of
soft sediments aimed for detailed stratigraphic analyses. Over the past decades a variety of freeze corers have been designed,
from very simple metal tubes filled with dry ice that are dropped into the sediment to high-tech samplers using electric pumps,
hydraulics and liquid nitrogen. The freeze corer described here is a compromise of getting good samples without a too complicated
technique. It is designed for coring from lake ice, using a steel wire with a stopper on the ice to keep the corer in fixed
position during freezing. It consists of a thermos connected to a thin freeze wedge (width 15 cm, length 100 cm, max thickness
6 cm). The dry ice is kept in the thermos until the freeze wedge has been lowered into the sediment to avoid water freezing
on the wedge during descent through the water column; a wet steel-wedge surface disturbs the sediment stratigraphy less than
a wedge on which rapid freezing occurs. The dry ice is kept in the thermos by a trapdoor that is opened by a messenger. When
the trapdoor is opened the dry ice begins to drop into the wedge, which is filled with ethanol. This process continues concurrently
with the consumption of ice in the wedge until the thermos is empty. Using 6–8 kg of dry ice and 4 l of ethanol (95%), a 3-cm-thick
and up to 80-cm-long crust of frozen sediment is obtained in 20–25 min on each side of the wedge. The crust is easily detached
intact from the wedge using a small volume of hot water, poured inside the wedge. 相似文献
7.
Kurt A. Haberyan 《Journal of Paleolimnology》2001,26(2):219-223
Materials for constructing a simple piston corer are available at most well-stocked hardware stores, primarily using galvanized fence post for the barrel, and pipe for the drive rod and head. These are assembled with a modicum of machinist skills. In the field, this VolksCorer operates like similar corers; it is limited to relatively shallow water (about 10–15 m) and is poorly suited for down-the-hole coring, but it requires few specialized tools. Likewise, materials to construct the VolksExtruder are widely available; this extruder, although simple, allows very precise extrusion control. The very low cost of the corer and extruder (less than US$50 each) make them suitable for investigators operating with low budgets without sacrificing sample quality. 相似文献
8.
A new hammer-driven freeze corer 总被引：1，自引：0，他引：1
Brenda M. Miskimmin P. Jefferson Curtis David W. Schindler Nestor Lafaut 《Journal of Paleolimnology》1996,15(3):265-269
A shortcoming of freeze corers has been the inability to collect long cores in stiff sediments. We describe a hammerdriven freeze corer that collects undisturbed sediment cores up to 1.3 m in length in stiff or soft lake sediments. The corer was tested in prairie, montane and alpine lakes of western Canada. For these stiff sediments, conventional (gravity-only) freeze coring methods collected cores ranging from 25–59 cm compared with 100–124 cm for our hammer-driven device. The maximum length of cores could exceed 1.3 m if a longer core barrel was constructed. 相似文献
9.
A freeze corer was developed specifically for the sampling of unconsolidated surface sediments by in-situ freezing. The new device which is presented here is designed to be used to a water depth of up to 1000 meters and was successfully tested at a depth of 200 m. The corer consists of a high pressure resistant housing with a vacuum insulated jacket for the ethanol which can be chilled by separate cooling agents, adjustable stabilizing legs, an electrical pump and a freezing wedge of 100 cm length. The freeze coring can be performed from a platform or a boat by using only a single cable to pull it up or to lower it. All other equipment is inside of the resistant housing. The core sample can easily be cut into two distinct slabs by use of the freeze-protectors on the small sides of the freeze wedge. 相似文献
10.
Ian R. Patmore Carl D. Sayer Ben Goldsmith Thomas A. Davidson Ruth Rawcliffe Jorge Salgado 《Journal of Paleolimnology》2014,51(1):79-86
We present a design for a large diameter piston corer, deployed from a raft that is suitable for use in shallow lakes. The piston corer, known as Big Ben, consists of a core tube, a piston on a rope and a corer head, to which rods are attached to drive the tube into the sediment. A core catcher, which aids the support of the core tube when full of sediment, has been incorporated into the design. To extrude the sediment, a framework has been designed to keep the core tube upright and stationary and a modified bottle jack is used to push the piston upwards during the extrusion process. The practical operation of the Big Ben coring system from setting up a coring platform to collecting and safely extruding a core is detailed. Finally we summarise recent experiences of deploying the corer and highlight its potential uses in the developing field of multi-proxy palaeolimnology. 相似文献
11.
Parachute-assisted gravity sediment corer (Algonquin Corer) 总被引：1，自引：0，他引：1
Details are outlined for the construction and use of an easily constructed and inexpensive parachute-assisted, gravity-driven, sediment coring device. This corer has been named the Algonquin corer since it was designed, tested and constructed at École Secondaire Algonquin, North Bay, Ontario. This corer utilizes an underwater parachute to effectively control and stabilize its descent, and a driving mechanism (hammer) to increase the penetration of the corer. Other innovative features are its corrective mercury and magnetic switches, which allow the user to precisely monitor both the position of the driving mechanism and the corer's angle of sediment penetration. These optional features may be constructed for use with this particular corer or constructed separately to enhance existing coring devices. Details of these features are provided and their functions outlined. The versatile features, cost-effectiveness and ease of construction of the Algonquin corer make it an effective and practical tool for conducting sediment analysis studies at all levels. It is also well suited for the instruction of coring techniques and paleolimnological methods at both the university and high school level. 相似文献
12.
Within-lake variability of subfossil chironomid assemblages in shallow Norwegian lakes 总被引：3，自引：5，他引：3
Oliver Heiri 《Journal of Paleolimnology》2004,32(1):67-84
Subfossil chironomids in the surface sediments of five small and shallow Norwegian lakes were studied to determine the within-lake variability of fossil assemblages, changes in chironomid assemblages with respect to water depth, and the representativeness of single samples for the entire chironomid fauna of a lake. In each of the lakes studied, six short sediment cores in the deepest part of the lake basin and two littoral to deep-water transects of seven cores each were obtained using a gravity corer, and chironomid assemblages in the uppermost centimetre of sediment were analysed. In three of the five lakes, chironomid concentrations were highest in the deepest parts of the lake basins. In the remaining two lakes, concentrations were either very variable or, in a lake with clear indications of anoxia in the bottom waters, highest at intermediate water depth. Chironomid assemblages tended to be dominated by the same taxa within a lake basin. However, in each of the lakes studied there was a clear and statistically significant shift in chironomid assemblages with respect to water depth. The organic content of the sediments was statistically significant in explaining the variance in the chironomid assemblages only in lakes where organic matter content was closely related to water depth. Only a few chironomid taxa were restricted to the shallowest parts of the lake basins, whereas a number of chironomids were found exclusively in deep-water sediments. Chironomid head capsules of running water taxa and simuliid remains were generally found in sediments close to lake tributaries and in the deepest parts of the lake basins. Although any individual sample contained only a part of the total subfossil chironomid fauna (21–63% of the total taxa per lake), chironomids dominant in any section of the study lakes were found in most of the transect and mid-lake samples. 相似文献
13.
R. J. Flower D. T. Monteith A. W. Mackay J. M. Chambers P. G. Appleby 《Journal of Paleolimnology》1995,14(2):101-111
The Baikal sediment box corer represents an innovation in design of the closing mechanism and involves a single, thin, and flexible stainless steel blade rather than closing jaws. With this light-weight box corer only a relatively small cross-sectional area is offered to the sediment, allowing easier penetration. The closure blade is propelled smoothly across the base of the box in a downwardly convex path by a set of constant force springs. Depending on choice of blade-release mechanisms, the corer can either be triggered immediately as the support cable slackens, after a delay of a few seconds, or immediately upon retrieval. The box corer has been used successfully to sample poorly consolidated sediments in freshwater lakes over a depth range of 8 to 1624 m. Cores of deep-water surficial sediment from Lake Baikal were tested for representativity and replicability by profiling natural and artificial radioisotopes and lithostratigraphic features. 相似文献
14.
We present a design for a piston corer that can take a sediment core up to 1 m long, with an undisturbed sediment–water interface.
The coring device possesses a tripod unit and a core-tube unit, the latter comprised of a core tube, a piston with a wire,
a drive weight in which the core tube is mounted and a steel rod. The tripod stands on the sediment surface during coring,
stabilizing the system and serving as an anchor point for the piston wire. A ball clamp, the critical component of the design,
is mounted on top of the tripod. The steel rod runs through the ball clamp and at its lower end, holds the drive weight and
the core tube. The ball clamp allows the core tube to slide downward, while the piston is held in a fixed vertical position
by the wire connected to the tripod. When the corer is lifted, however, the ball clamp locks. This makes it possible to operate
the corer with a single cable, because the piston is not subject to any lifting force when the corer is retrieved. The piston
remains in position in the core tube even if the collected sediment core is very short. The piston corer can be deployed from
a raft or a boat. 相似文献
15.
Mel A. Reasoner 《Journal of Paleolimnology》1993,8(3):273-281
This paper describes improvements for an inexpensive, lightweight percussion core sampling system and presents examples of recovered core. The system has proven most effective in remote settings where the weight of a coring system may be a constraint. Cores of up to 5.5 m in length have been recovered and the system has functioned successfully in water depths to 200 m. The system weighs approximately 25 kg and costs less than $450.00 (US).The percussion corer is designed for operation from a stable ice-pack surface. The core barrel assembly is lowered through the water column and driven into sediment with a weighted driver. A secondary line is used to raise and drop the driver. The driver is guided to the core barrel assembly by the main line. Cores are retrieved by a simple pulley system anchored to the ice pack. 相似文献
16.
We describe an improved piston corer, the Mk II, for sampling soft sediments for ancient DNA analysis. The original Mk I model,
designed to minimize contamination and successfully used in New Zealand, was subsequently deployed on Easter Island where
three problems arose. Two of these problems related to sediment and water entering the core barrel and contaminating samples.
The other difficulty was that plant material accumulated ahead of the piston and blocked the corer aperture. Design improvements
were made to the prototype model and eliminated these problems. 相似文献
17.
Paleohydrologists sometimes use macrofossils of aquatic vascular plants as one of several independent lines of evidence to infer changes in past lake-levels. Typically, this usage relies on an assumption that the seeds of aquatic species are not dispersed far from the source plants. The water depth over the coring site at the time the seeds were deposited is inferred from the water depth at which the species generally grows today. We determined the water depths at which particular plant-remain types are deposited, and tested whether they can be used successfully as proxy evidence for lake level. The results should aid the interpretation of fossil seeds in paleohydrological studies. A total of 189 surface sediment samples from 13 lakes in Maine and Massachusetts were examined for plant remains, and vegetation was surveyed in the immediate vicinity of each sediment sampling-site. The seeds of some taxa were found in sediment from water-depth ranges much broader than those in which living plants occur. However, in combination, even plant-remain types with broad depth ranges can be used effectively to reconstruct water depth. Presence of plant-remain types can be used to infer water depth regardless of abundance. Test samples indicate that inferring water depth from plant remains works well for shallow, alkaline lakes in New England. 相似文献
18.
Dirk Veerschuren 《Journal of Paleolimnology》2000,24(3):361-365
A new freeze corer is described that is specifically designed for operation in warm tropical lakes. It combines the standard wedge-shaped freeze-on container with a 20-liter thermos from which pellets of solid CO2 descend into the wedge to replace those that have sublimated. This extends the duration of effective freezing from ~20 to ~45 min, sufficient to form an adequate thickness of frozen crust in warm (> 22 °C) lakes and prevent its premature melting during retrieval through the water column. The instrument contains no electrical components, which simplifies construction, operation, and maintenance. The front and back surfaces of the freeze wedge are fitted length-wise with serrated ridges to facilitate removal of the crust as four rectangular sediment slabs. The feasibility of freeze coring studies in tropical regions is mainly determined by the local availability of a large-volume dry ice producer. 相似文献
19.
Gravity corers have been in use for a long time and in many different configurations. There are, however, reasons for improvements
since new manufacturing materials have become available, and demands for accurate coring and sub-sampling in both research
and environmental monitoring have increased. The HTH-coring equipment, which has been tested for >10 years by several users,
is a further development of the Kajak-corer concept and has some unique features which are described here. To avoid contamination
in pollution studies, the equipment is made of stainless steel and plastic (polyoxymethylene and polyethylene), and the use
of these materials also makes the equipment more durable. The extruding device is the main improvement over previous versions.
It consists of a piston that seals perfectly to the core tube wall, a threaded rod that can be mounted on a foot plate, and
an extruder head with a stationary upper-half and a rotatable lower-half that is screwed along the rod. One 360°-turn gives
a 5-mm thick sediment increment that is scraped off using the sectioning tray. Sub-sampling is quick and accurate and can
be performed by one person. The equipment is constructed to allow coring and sub-sampling both in summer and winter. 相似文献
20.
Jens Mingram Jörg F. W. Negendank Achim Brauer Dieter Berger Andreas Hendrich Michael Köhler Hartmut Usinger 《Journal of Paleolimnology》2007,37(4):517-528
We present a unique, versatile piston corer for recovering continuous lake and bog sediment sequences with superior accuracy
and quality. The main components of the system and their function are described, with special focus on measures for obtaining
long, continuous lake sediment sections up to a current maximum length of 95 m. Examples of lake sediment profiles obtained
with this system from different climatic zones are presented. 相似文献