Comparison of two gravity coring devices for sedimentation rate measurement by 210Pb dating techniques

Marine sediment cores were collected in Puget Sound using a 7.6 cm diameter corer and a 15 × 15 cm square cross-section corer. The cores were dated by the ²¹⁰Pb method and sedimentation rates and depth of sediment mixed layers were compared. The results show that both the sedimentation rates and the depth of sediment mixed layers obtained from small diameter corer are 2–3 times smaller than the corresponding values obtained from large cross-section corer. A cross-calibration of coring techniques seems necessary to correlate the sedimentation rates obtained using different devices.     

A pedal corer for the quantitative sampling of sediments and benthic organisms in submerged areas accessible on foot

This paper presents a new device to collect quantitative samples of sediment and benthic organisms. The device is specially designed for sampling with the advantages of box-corer or Eckman dredges in submerged areas that are accessible on foot. The pedal corer is a simple, lightweight, user-friendly device that does not disturb the sediment structure and provides easy access to the sample contained inside the core. With this device, sampling in shallow water zones that are constantly submerged is made easy and sampling time is extended in intertidal zones. Handling editor: J. Saros     

The propagation and dispersal of misinformation in ecology: Is there a relationship between citation accuracy and journal impact factor?

The biological and physico-chemical structure of near bottom habitats located under densely growing submerged vegetation, and their significance in the functioning of whole aquatic ecosystems, are very little known due to difficulties in sampling. Corer-type samplers, believed to be the best in littoral studies, do not work properly in such places, because their tube opening is easily clogged by plant shoots, acting as a stopper. In order to overcome this problem, an alteration to the shape of the tube ending is proposed. This can be done by its trimming at an accurate angle, or by fitting (permanently or interchangeably) a metal collar made of stainless steel to its end, so that the ending would resemble the shape of a needle. The modification can be applied to virtually all corer samplers. It was found to be efficient while sampling sediment cores for the purposes of both hydrobiological and paleolimnological studies on heavily overgrown macrophyte-dominated water ecosystems.     

The tom-tom corer: a new design of the Kajak corer for use in meiofauna sampling

A new corer, the tom-tom, is a modification of the basic Kajak design. New modifications increase the efficiency of the corer in soft muds and increase the stability of the corer during ascent and descent. A stepped release trigger mechanism allows the corer to trip easily in even the softest muds, and a Phleger “bomb’ weight adds stability to the device. The corer can be deployed in a slow, controlled descent from small as well as large boats to reduce bow-wave. Four cores (4.50 cm inner diameter) are taken simultaneously in a fixed spatial pattern. Limited comparative sampling revealed that the tom-tom collected more meiofauna than a Van Veen grab and attained numbers statistically indistinguishable from diver-collected cores (only small sample sizes were available however). The corer will be most efficient in sediments without an extremely well-developed, suspendable layer, and most practical for smaller vessels in environments where diver collected cores are precluded by depth, strong currents or poor visibility. Although used in meiofauna collection, the corer should be appropriate for any sampling needs requiring a relatively undisturbed core.     

Changes in microphytobenthos fluorescence over a tidal cycle: implications for sampling designs

The breakdown rate of leaf litter buried inside river sediments (i.e., in the hyporheic zone) remains poorly known. The burial of large bags (15 × 15 cm) used in the benthic layer generates disturbances of the vertical connectivity with surface water, and thus affects the breakdown rate. We performed field and laboratory experiments to test the suitability of two leaf litter containers: small litter bags (5 × 4 cm) and perforated stainless steel cylinders (6 cm long, 1.6 cm in diameter), both introduced inside sediments using mobile mini-piezometers (1 m long, 1.7 cm or 3 cm in diameter). We compared the two containers for (i) the hydrological exchanges toward leaf litter, (ii) the impact of a benthic shredder on leaf breakdown, and (iii) the response of leaf litter breakdown to changes in sediment characteristics. The two methods give similar patterns of breakdown rates with stream sediment characteristics, but the use of perforated stainless steel cylinders provides an artificial empty volume in which invertebrates can over degrade leaf litter. Small plastic bags do not alter physico-chemical conditions around leaf litter and give lower values of breakdown rates in the hyporheic zone.     

A comparison of lead and zinc sediment profiles from cores taken by diver and a gravity corer

The zinc and lead concentrations were compared in several pairs of sediment cores obtained with a modified K-B corer and by Scuba diver from Coon Lake, Canada. A slow approach to and penetration of the sediments (ca. 0.1 m s^-1) was employed for both coring devices. The modified K-B corer gave similar lead and zinc profiles to the diver cores. The divers observed that the K-B corer caused no disturbance of the surface sediment layers as it approached and entered the sediments. These results suggest that the K-B corer is suitable for use in lake studies requiring short, undisturbed cores from fine-grained sediments.     

A new sampler for extracting undisturbed surface peat cores for growth pot experiments

The sampler extracts uncompressed cores of 13·3 cm in diameter, up to 70 cm long, from the surface layers of peat. It has two close-fitting concentric cylindrical tubes, the outer one acting as a cutter and the inner one as a collector. As the outer tube is introduced by rotation into the peat, the cut core is collected in the inner tube which is maintained in a fixed position during the rotation phase and then pushed down stepwise. This limits friction between the peat core and the wall of the corer and prevents compression or distortion of the peat. These problems are also reduced by means of three skew cutters allowing the peat to be supported during the slicing action. Air can penetrate between the tubes to the lower end of the core, suppressing any suction effect during withdrawal. The sampler has been tested and has worked satisfactorily in many different peat types.     

Detecting intra-site patterns with systematic sampling strategies. Archaeobotanical grid sampling of the lakeshore settlement Bad Buchau-Torwiesen II, southwest Germany

At the late Neolithic site Torwiesen II (3283 and 3279 cal. b.c.) a systematic sampling programme was carried out, covering the entire settlement area. Plastic tubes, 10 cm in diameter and 20–30 cm long were used for sampling, in which one sample per square metre was taken. For each plant species in every analysed sample the concentration, in remains per litre of sediment, was calculated and plotted with AutoCAD. Every plot shows the quantitative distribution of a taxon on the site and indicates a special pattern that may reflect economic conditions or even social differences within the settlement. With the plots, areas of special activity inside and outside the houses were detected: zones of crop processing, cooking areas and rubbish deposits. The socio-economic structure of the settlement with unspecialised farmers, crop specialists and gatherers is indicated by the content of crops and edible wild plants inside the houses. On the basis of the systematic sampling programme it could be shown that Torwiesen II was not a consistent community, but much more a structured one.     

Water level fluctuations in Lake Baringo,Kenya, during the 19th and 20th centuries: Evidence from lake sediments

This article presents a fossil diatom-based, semi-quantitative reconstruction of water level fluctuations for Lake Baringo over the past 200 years as a consequence of climatic variations. A 285 cm long sediment core sample was collected using a Rod-Operated Single-drive Stationary Piston corer. Lake level was inferred using indices based on the proportion of planktonic to benthic diatom taxa (P/B ratio). The sediment archive presented distinct zones dominated by planktonic and benthic diatom flora. An initial transgression in the early 19th century was characterised as a shallow water environment dominated by planktonic Aulacoseira spp. This was a response to extreme drought during the late 18th to early 19th century. Mid-19th century was defined by a high lake stand. The late 19th to early 20th centuries experienced low water level following the widely documented aridity at the time. The mid-20th century was marked by a spectacular rise in water level that coincided with remarkably wet years during the early 1960s and late 1970s. The first decade of the 21st century witnessed widespread changes in water level. The proxy records show that lake ramping and drawdown over the years follow approximately 50-year climatic cycles.     

A floatable,benthic corer for use with scuba

A diver-operated corer to sample benthic macroinvertebrates is described. Removable drive-handles allow the 9-cm (ID) barrel to be driven into substrates too firm to be sampled by line-held or conventional diver-operated corers. The sampler is emptied underwater using compressed air and its buoyancy can be controlled by filling a rubber inner tube.This study was supported by the Pennsylvania Power and Light Company     

Automatic Sampling and Analysis of Organics and Biomolecules by Capillary Action-Supported Contactless Atmospheric Pressure Ionization Mass Spectrometry

Contactless atmospheric pressure ionization (C-API) method has been recently developed for mass spectrometric analysis. A tapered capillary is used as both the sampling tube and spray emitter in C-API. No electric contact is required on the capillary tip during C-API mass spectrometric analysis. The simple design of the ionization method enables the automation of the C-API sampling system. In this study, we propose an automatic C-API sampling system consisting of a capillary (∼1 cm), an aluminium sample holder, and a movable XY stage for the mass spectrometric analysis of organics and biomolecules. The aluminium sample holder is controlled by the movable XY stage. The outlet of the C-API capillary is placed in front of the orifice of a mass spectrometer, whereas the sample well on the sample holder is moved underneath the capillary inlet. The sample droplet on the well can be readily infused into the C-API capillary through capillary action. When the sample solution reaches the capillary outlet, the sample spray is readily formed in the proximity of the mass spectrometer applied with a high electric field. The gas phase ions generated from the spray can be readily monitored by the mass spectrometer. We demonstrate that six samples can be analyzed in sequence within 3.5 min using this automatic C-API MS setup. Furthermore, the well containing the rinsing solvent is alternately arranged between the sample wells. Therefore, the C-API capillary could be readily flushed between runs. No carryover problems are observed during the analyses. The sample volume required for the C-API MS analysis is minimal, with less than 1 nL of the sample solution being sufficient for analysis. The feasibility of using this setup for quantitative analysis is also demonstrated.     

Shortening of surface sediment cores during sampling

Coring in recent lake sediments is most easily performed using lightweight open barrel gravity corers. The cores will in most cases have the fine lamination intact and they may thus be interpreted as representative of the sediment in situ.Parallel cores taken by means of other techniques have shown that cores taken with open barrel gravity corers become shorter than the distance of penetration in the sediment. This investigation shows that the shortening depends both on the corer diameter and on its velocity during the penetration. Experiments also show that soft layers become more reduced in thickness than stiffer ones. This may lead to misinterpretation of sedimentation rate during special periods. Seasonally occurring sediment fractions may be diluted or concentrated during the coring.     

A simple apparatus for sampling epiphytic communities associated with emergent macrophytes

The apparatus allows the sampling of both algal and animal components of the epiphyton. It consists of a perspex tube, 100 cm long with an internal diameter of 4 cm, and of an epiphytic sieve. The latter is made of two 2.5 cm cross-sections of perspex tubing with a piece of circular mesh glued between them. While sampling, a randomly chosen shoot is isolated from the ambient water by means of the tube, cut at the bottom sediment and removed together with epiphyton. The water, taken together with the shoot is then removed using the epiphytic sieve, joined with the tube under the water surface. The detached organisms, associated with the stem and those scraped from the stem with a stiff brush afterwards, concentrate on the mesh.     

Relationship of species composition of tropical seagrass meadows to multiple physical environmental factors

The purpose of this study was to examine the relationship between species composition of tropical seagrasses and various physical environmental factors: depth, sediment thickness and silt–clay content in the sediments. We investigated species composition and abundance of seagrasses as well as the physical environmental factors for six transects around Ishigaki Island, southwest Japan. Eight species occurred in the quadrat census. The occurrence frequencies ranged from 66.8% (Thalassia hemprichii) to 4.5% (Enhalus acoroides). Both canonical correspondence analysis (CCA) and cluster analysis elucidated that depth was mainly responsible for the distributions of species and assemblage type. Monte Carlo permutation for partial CCA revealed that 37.5% of the variance was explained by depth, 10.3% by sediment thickness and 4.6% by silt–clay content in the sediment. Twenty-six sites were categorized into four assemblage types by a cluster analysis using the leaf area index (LAI; the ratio of total leaf area to bottom area) as a measure of species abundance. Type I was dominated by T. hemprichii and Cymodocea rotundata, Type II by C. serrulata, Type III by E. acoroides, and Type IV by Halodule pinifolia and Halophila ovalis. Type I occurred mostly in the intertidal zone (91.3±30.5 cm below MSL, mean sea level), Type II in the subtidal zone (179.1±75.0 cm below MSL) and Type IV in both shallow sites (between 47.8 and 75.6 cm below MSL) and in those with low silt–clay contents (between 2.0 and 3.8%).     

Sterilization of various diameter dead-ended tubes

Effect of tube diameter on steam-in-place sterilization of dead-ended tubes was studied by examining temperature profiles and rates of kill of Bacillus stearothermophilus spores. Time required for sterilization was determined for 9.4-cm-long tubes with various inside diameters from 0.4 to 1.7 cm. Sterilization time increased with decreasing tube diameter. Experimentally measured kill kinetics in 1.7-cm tubes were in agreement with those predicted if measured temperatures represented saturated steam. A 12-log spore reduction was achieved in 1.7-cm diameter vertical and horizontal tubes in less than 63 minutes. For smaller diameter tubes, entrapped air remained after 2 hours and rates of kill were very dependent on position within the tube, tube diameter, and tube orientation with respect to the gravitational vector. Times to achieve a 1-log drop in spore population in the smaller tubes were as much as 10 times greater than those expected if measured temperatures represented saturated steam. Sterilization was not achieved throughout the 0.4-cm tubes. Recommendations are made for including steam bleeders or using prevaccum cycles for these smaller diameter tubes. (c) 1993 John Wiley & Sons, Inc.     

Sediment Core Extrusion Method at Millimeter Resolution Using a Calibrated,Threaded-rod

Aquatic sediment core subsampling is commonly performed at cm or half-cm resolution. Depending on the sedimentation rate and depositional environment, this resolution provides records at the annual to decadal scale, at best. An extrusion method, using a calibrated, threaded-rod is presented here, which allows for millimeter-scale subsampling of aquatic sediment cores of varying diameters. Millimeter scale subsampling allows for sub-annual to monthly analysis of the sedimentary record, an order of magnitude higher than typical sampling schemes. The extruder consists of a 2 m aluminum frame and base, two core tube clamps, a threaded-rod, and a 1 m piston. The sediment core is placed above the piston and clamped to the frame. An acrylic sampling collar is affixed to the upper 5 cm of the core tube and provides a platform from which to extract sub-samples. The piston is rotated around the threaded-rod at calibrated intervals and gently pushes the sediment out the top of the core tube. The sediment is then isolated into the sampling collar and placed into an appropriate sampling vessel (e.g., jar or bag). This method also preserves the unconsolidated samples (i.e., high pore water content) at the surface, providing a consistent sampling volume. This mm scale extrusion method was applied to cores collected in the northern Gulf of Mexico following the Deepwater Horizon submarine oil release. Evidence suggests that it is necessary to sample at the mm scale to fully characterize events that occur on the monthly time-scale for continental slope sediments.     

用Minirhizotrons观测柠条根系生长动态

 Minirhizotrons是一种非破坏性、定点直接观察和研究植物根系的新方法。该文介绍了用Minirhizotrons测定植物根系的方法,并同根钻取原状土样法进行了比较;探讨了根系生长动态同土壤含水量间的关系。试验于2004年植物生长季在沙坡头沙漠试验研究站的水分平衡观测场的人工柠条(Caragana korshinskii)林进行,结果表明：Minirhizotrons 管埋入土壤后需要10个月时间允许柠条根系在其周围定居,其观测图片中的根系代表了管子周围2.6 mm土层的根系。柠条根系生长动态和土壤水分变化相关,含水量的升高导致根系的大量繁殖,而根系吸水及蒸发散又导致含水量的减少;在2004年植物生长季,土壤水分和根系的这种相互作用出现了两次,但根系生长高峰比土壤含水量高峰滞后20 d左右。     

Compact optical microfluidic uric acid analysis system

We designed, fabricated and tested a novel compact fluorescence analysis system for quantification of uric acid (UA) in clinical samples at the point-of-care. To perform an analysis, diluted saliva, urine or blood samples are simply placed in a disposable thin-film sample holder using a dropper. A new enzyme immobilization technique was developed to retain within the sample holder two enzymes and a molecule, which transforms into a fluorescer in amounts depending on the UA concentration. The small instrument (7.5 cm × 5 cm × 5 cm) into which the sample holder is placed for analysis contains an LED, a narrow-band filter and an amplified photodiode. The analysis time is 30s, and the dynamic range of the system is 4-400 μM of UA. The calibration curve for transparent saliva and urine was made using solutions of UA. The calibration curve for opaque blood was obtained with spiked samples of blood. The three different types of clinical samples were collected from three subjects and simply diluted before their measurements. Analysis with our instrument yielded UA concentrations within the expected concentration ranges. Development of instruments based on the current laboratory prototype is expected to result in products for clinical trials and point-of-care.     

Soil seed banks in Pinus ponderosa forests in Arizona: Clues to site history and restoration potential

Question: How does the relationship between the viable soil seed bank species composition and the above‐ground vegetation in northern Arizona Pinus ponderosa forests differ under varying historical land use disturbances (low, intermediate, high)? Is above‐ground vegetation correlated to the viable soil seed bank immediately following soil disturbance from restoration thinning treatments? Location: Northern Arizona, USA. Methods: Soil seed bank samples were taken along replicated transects and collected with a 5‐cm diameter bulk density hammer. Samples included a 5 ‐cm diameter O‐horizon sample (at varying depths) plus the underlying mineral soil to a depth of 5 cm. The seedling emergent method was used to quantify seed bank species composition and density. The herbaceous and shrub plant community was quantified along the same transects using the point intercept method. Results: Early‐successional or ruderal species were common in the soil seed bank at all three disturbance sites. Non‐native species, notably Verbascum thapsus, were more numerous (up to 940 seeds/m²) under high disturbance with overgrazing and logging, and less common or absent under low disturbance. Most viable seeds were found in the O‐horizon and the upper 5 cm of mineral soil; there was little correlation between species in the soil seed bank and the above‐ground vegetation. Conclusions: We recommend that restoration plans be geared toward minimizing activities, such as severe soil disturbance, that may promote the spread of non‐native invasive species, and that manual seeding be explored as an option to restore plant species diversity and abundance.     

Meiofauna of silty sediments in the coastal area of the North Adriatic,with special reference to sampling methods

At five coastal silty sediment stations ranging in depth from 8 to 30 m, the abundance and composition of meiofauna were investigated. Three methods of sampling were used, i.e. Pfleger corer, Van Veen grab and SCUBA divers. Four samples per station were taken. The mean density of total meiofauna was 660 ± 109 ind. 10 cm². The main meiofauna group was Nematoda, the second abundant was Copepoda, and third was Kinorhyncha. Statistical tests showed significant differences in meiofaunal abundance between corer and grab samples, and between corer and divers samples.Differences in meiofauna abundance between stations were found.