DE102004053111B3 - Sampling device for the simultaneous collection of pore water from adjacent aquatic sediment areas and use thereof - Google Patents

Abstract

It is known to use a sampling device with miniaturized filter tubes with hydrophilic microporous plastic tubes on the receiving side for the simultaneous extraction of pore water samples from different saturated sediment areas for the purpose of geochemical and biogeochemical investigations of the sediment-water transition zone. However, this sampling device destroys the sediment surface during insertion and does not measure under the current environmental conditions but on land. The sampling device (PNG) according to the invention therefore has a blade-like housing (SG) which can easily be inserted into the sediment area (SB), in the narrow end face (SSS) of which a number of samplers (PN) are arranged vertically one above the other. These can be inserted manually or by way of a motor (also automatically) operable traversing device (VE) individually or collectively horizontally in the adjacent superimposed sediment areas (SB) and also withdrawn, whereby the process of pore water production can be repeated several times at different times. Thus, high-resolution vertical parameter profiles in the undisturbed sediment area (SB) can be recorded. Advantageously, above this sediment area (SB) in one application, a benthic chamber (BK) may be provided for measuring mass transfer across the sediment-water interface.

Description

The The invention relates to a sampling device for the simultaneous collection of Pore water from adjacent aquatic sediment areas with several, in a housing arranged in a row miniaturized samplers with a hydrophilic microporous Plastic hose on the receiving side for the pore water with a support rail and on the submission page for the pore water with a suction device and a storage device connected, and on an application of it.

One such sampling device serves the simultaneous extraction of pore water samples from aquatic Sediments for the purpose of geochemical and biogeochemical investigations the sediment-water transition zone. Processes in the sediments and in the soil water produce gradients, z. B. in geochemical concentrations, in pore water. Especially the degradation of organic matter and the release of minerals a gradient in the pore water. Often, pore water is made from sediments sampled ex-situ, with a sediment core, for example, aboard a Ship or landed and the sediment divided into sub-samples becomes. These are then squeezed out with pressure or centrifuged, to gain the pore water. This can be a change pore water chemistry due to temperature, pressure and undesirable oxidation and contamination processes.

Increasingly, therefore, in situ systems are used to sample the sediment in its natural environment. From the publication I: "The ROLAI ² Dander: a benthic lander for the study of exchange across the sediment-water interface" by FL Says et al. (Deep Sea Research, Vol. 38, No. 5, pp. 505 -529, 1991), the so-called "whole core squeezing" is known, in which a free-falling support system for devices for testing the seabed ("lander") is deposited on the sediment, thereby enclosing a sediment core in a sample tube. The sediment is then squeezed out by pressure from above and below. The pore water escapes through openings in the sample tube into collection vessels. The disadvantage here is the very complicated and expensive application of the sampler. In addition, the sediment can be sampled only once, because the sediment composite is destroyed during sampling. Since the sediment is compacted during extrusion and thus passed during the sampling of the openings in the sample tube over, it is difficult to assign the sampling locations a defined horizon (sediment depth). Furthermore, the so-called "peeper" method is known from publication II: "An in situ sampler for close interval pore water studies" by RH Hesslein (Limnology and Oceanography 21 (6), Nov. 1976, pp. 912-914) , This method works on the principle of diffusion. The sampling device consists of a body with many chambers that are filled with distilled water and covered by a membrane. The sampling device is installed in the sediment, after which a balance between aqueous humor and pore water is established by diffusion. After adjustment of the equilibrium, the sampling device is retrieved and the pore water in the chambers analyzed. The disadvantage of this method is that the sampling device must remain in the sediment for a very long time in order to sample the sediment. Furthermore, only a single sampling can take place so that short-term parameter changes in the sediment can not be detected. Furthermore, there is a risk that the balance has not yet adjusted when removing the sampling device. A third in-situ method is disclosed in Publication III: "A new device for in-situ pore-water sampling" by A. Bertolin et al. (Marine Chemistry 49 (1995) 233-239) with a suction sampler. This is a sampling device, which consists of a blade-like housing having in its narrow end face in their size predetermined, usually protected by filter or gauze openings, is sucked through by the application of negative pressure pore water located behind the openings reservoir. A disadvantage of this method is the very high adaptation time of the sampling device in the sediment of about 2 weeks before sampling of the sediment can be carried out and the pore water is sucked in over relatively large areas, so that only a poor vertical resolution can be achieved. Finally, the amount of pore water that can be aspirated is very limited if it is not contaminated from other horizons in the sedim should be taken. It is also particularly disadvantageous in all three in-situ sampling devices that they destroy the sediment surface upon penetration into the sediment. Thus arise undesirable artificial mixing zones, also z. For example, a so-called "benthic chamber" is not used at the same time: it is a bottomless cylindrical chamber that is placed on the sediment, and changes in the concentrations in the volume of water incubated in the chamber provide information about the sediment exchange. By rotating the lid of the benthic chamber or a stirrer below the chamber lid, a three-dimensional flow can be created inside the chamber that also flows through areas of the sediment Have an influence on the transport of dissolved and particulate matter on the seabed. The benthic chamber is a suitable means of experimental study of such transport operations.

Out the publication IV of the University of Bremen "Pore water sampling with Rhizon sampler "by M. Kölling (available on the internet at http://www.geochemie.uni-bremen.de/koelling/rhizon_p.html) As of 20.10.2004) is the collection of pore water use of miniaturized samplers with a hydrophilic microporous plastic tube, the on the recording side for the pore water with a support rail and on the issue page for the pore water is connected to a suction device known. The so-called "Rhizon Soil Moisture Sampler" is around a miniaturized filter tube with a microporous Polymer tube on the receiving side and a vacuum resistant PVC hose on the delivery side, which represents an artificial root and developed for the collection of soil moisture in unsaturated soil zones became (compare prospectus P2.30 of the company Eijkelkamp "Soil Moisture Sampling "pp. 183-186, available on the Internet at http://www.waterland.com.cn/PDF/P2-30e.pdf, Stand 20.10.2004 and Prospectus Doc.No.1190 "Techlnfo Ben Meadows Company Rhizon Soil Moisture Sampler ", 2002 Lab Safety Supply Inc.). In the publication IV of the University of Bremen The described sampler is in a sampling device for simultaneous collection of pore water from adjacent aquatic sediment areas ex-situ sampling of marine saturated sediment. Thus, the known filter tubes are misused in some way. The sediment to be sampled is previously obtained in a tubular housing, which is then brought ashore and closed with a lid. In the housing wall are longitudinal axes parallel a series of small holes arranged through it the supported ones Plastic hoses introduced into the sediment can be. The samplers are thus arranged in a row and each one Pore water sample, either over a connected vacuum tube or about one Injection syringe as a suction device in a tube as a storage device can be assigned to a sediment area. If This sediment area is vertical or horizontal in the water bottom extends is the publication IV, however, can not be deduced. A disadvantage of this known sampling device of which the present invention as the closest State of the art is, on the one hand, in principle, the ex-situ extraction the pore water samples. Furthermore, the introduction of the leads tubular housing in the sediment area to be sampled to a massive disturbance of the natural Conditions. In particular, by the ex-situ measurement process and the destruction of the sediment surface also no measurements accompanying the sampling, for example with a benthic chamber.

The Task for The present invention is therefore to be seen in a miniaturized sampling device Samplers of the type described above, generic type so that on the one hand an in-situ sampling of the aquatic sediment carried out can be. This should be additional vertically high resolution be. On the other hand, this sampling without disturbing the sediment surface carried out so that accompanying investigations are carried out there can. The inventive solution for this Task is to refer to the main claim. Advantageous developments of the sampling device according to the invention in the subclaims are shown below and in connection with the invention explained in more detail. A advantageous application of the sampling device according to the invention results according to the application claim in-situ interaction with one on a waterbed settled benthic chamber, these being at such a distance to the sampling device is discontinued. that the sampler in the sediment area below the benthic chamber are extendable and the sediment surface within the benthic chamber undisturbed remains.

The sampling device according to the invention has a series of vertically arranged in a support device in a cutting-like housing sampler in the form of miniaturized filter tubes of the type described above. The support means is arranged in a housing that tapers in a wedge shape downwards. With this cutting-like design, the housing can easily penetrate vertically into the sediment without causing major damage to the sediment surface. Once the enclosure has reached its vertical penetration depth, typically located in the upper several decimeters of the sediment layer, the individual samplers, which are vertically stacked in the sediment and thus allow a high resolution vertical profile measurement in the sediment, can be activated. For this purpose, they are horizontally inserted from a narrow end face of the blade-like housing with their supported receiving sides in the lying next to the housing sediment area. The sampling is therefore not in the area of the housing, but in an undisturbed neighboring area. This is not significantly disturbed by the very small diameter of the extended sampler. Sampling does not require a long service life. Immediately after inserting the housing into the sediment, sampling can begin. It can be made a multiple sampling in the same sediment area by respective activation of the suction at predetermined intervals. The pulled pore water samples can be mixed or stored separately in the sampling device in appropriate storage devices. The repeated activation can also be carried out by repeated retraction and extension of the sampler, so that the time-observable conditions in the sediment can be adjusted completely undisturbed by the samplers.

In summary can be seen with the sampling device Pore water samples from different horizons in the upper decimetres of a undisturbed water sediment be recovered under in situ conditions. This will be a vertical high-resolution Sampling of pore water in the sediment allows one or more times at certain intervals can be made in order to investigate temporal changes. The so with the sampling device available pore water profiles can provide new insights into transport and reaction processes in the sediment and at the sediment-water interface. To the Exchange through this interface In addition, in an application of the claimed Sampling a benthic chamber in situ. So far it has not been possible to sample the pore water directly under such a chamber. By the lateral extension of the sampler from the blade-like casing of the sampling device however, this will be possible because the sediment surface immediately above the sampler is not through the sampling device destroyed becomes. Thereby can further investigations were carried out become. Thus, the sampling unit combines high functionality accordingly the theoretical requirements for high-quality pore water sampling by anoxic sampling, a small dead volume in the device and by the fact that the pore water through the sampler, which as miniaturized filter tubes with a microporous Plastic tube for pore water absorption are formed, already is collected in filtered form, with a high field fitness due to the low disturbance of the sediment to be sampled.

building block of the in-situ sampling device the samplers are in the form of rhizons. Rhizones are commercial available Soil moisture sampler. They usually exist on the recording side for the Pore water in one piece hydrophilic microporous Polymer hose, with a support rail, usually a support wire made of stainless steel or plastic, glued. The delivery side is connected with a PVC hose, through which by means of negative pressure a pore water sample can be sucked into a storage device. In this case, the bearing device can be formed in the simplest case as a tube it can be, but it can also multi-chamber storage containers be used. The important thing is the clear assignment of each separate storage container to the appropriate sampler for a correct profile profile create the respective measured variable to be able to. The suction device may, for example, be manual actuated Hypodermic syringes or a motor driven peristaltic pump act. Each sampler can be operated separately Assigned suction or a common suction for all Sampler be provided. It is both a manual operation of the Suction device as well as a motor and beyond an automated operation the suction device possible.

The samplers are installed in a carrying device such that, after the blade-like casing has been pressed into the sediment, they can be moved mechanically horizontally into the sediment. Two variants can be distinguished: each sampler is stored separately and can also be pushed separately into the sediment or all samplers are stored in a common support device and are pushed together into the sediment. In the first case, the support means for each sampler on a support member and for each support member, a separately operable Verfahrelement is provided in the traversing device. In this case, each support member may be formed as a tube which is fixedly connected to the support means and receives the sampler in the retracted state. The tubes thus act as protective tubes for the samplers in the retracted state. The samplers are mounted in angle rails so that they can be moved out of the front end of the tubes by moving the angle rails as part of the movement elements. For retracting and retracting each traversing element may have a bidirectional cable. This may, for example, be a type of "fishing line" attached to the angle rail of each sampler by means of two holes at the front and rear end of a tube The sampler can be pushed into or pulled out of the sediment, whereby each sampler can be operated separately, but all of the sampler's pulleys can also be run on a common support pole so that they - like a puppet guide - can be actuated simultaneously.

in the second case of joint storage, the support device is fixed connected to all samplers, with the sampler forward with their receiving sides protrude from the support, and movable trained. Also in this embodiment can be used as a drive a bidirectional cable can be used. This then attacks on front and rear end of the support device and can through Activation of the respective rope extend and retract the carrying device. A motor and above In addition, an automated adjustment with separate or common Drive is also possible without further ado.

embodiment

A Embodiment of the sampling device according to the invention will to their further understanding explained in more detail with reference to the schematic figures. It shows the

1A the sampling device in lateral cross section,

1B the sampling device in front view,

2 a sampler of the prior art in detail and

3 a recorded with the sampling device measurement diagram for two measurements.

The 1A shows in side cross-section a sampling device PNG for the simultaneous collection of pore water PW from adjacent aquatic sedimentary areas SB when used on a sea water bottom. The sampling device PNG has a largely closed housing SG, by the downwardly wedge-shaped tapered, cutting-like formation a largely vertical and stabilized penetration of the sampling device PNG in the sediment area SB due to the inherent importance of the PNG sampling device is easily possible. In the 1B is in the front view of the sampling device PNG the blade-like design of the housing SG clearly visible. In the housing SG six samplers PN in a support device TE are each arranged horizontally in a narrow end face SSS. Due to the vertical arrangement of the samplers PN one above the other, a vertical measurement profile of predetermined parameters in the sediment area SB can be recorded. For this purpose, the samplers PN with their receiving side ANS in the region of the narrow end face SSS from the blade-like housing SG in the sediment areas SB are horizontally extended and retracted.

I'm in the 1A illustrated embodiment, each sampler PN is slidably mounted in a separate tube RO as a support member TEL, which is fixedly connected to the support means TE. Shown are the extended into the sediment areas SB, supported by support rails SS receiving sides ANS the sampler PN. For this purpose, a traversing device VE is provided, which is constructed from a number of individual traversing elements VEL corresponding to the number of tubes. In the selected exemplary embodiment, each traversing element VEL consists of a manually or motor-driven (also automatically) driven bidirectional cable BSZ, which is fastened at the front and rear end with an angle rail fixedly connected to the sampler PN. By activating the respective end of the cable BSZ, the sampler PN is pushed together with the angle rail out of the protective tube RO as a support element TEL, so that its receiving side ANS penetrates into the sediment areas SB, or pulled back into the tube RO.

In another, in the 1A not shown embodiment, all sampler PN are firmly connected to the support device TE. This may be, for example, a simple perforated plate and a central support bar. All samplers PN project beyond the carrying device TE with their receiving sides ANS. By moving the entire support device TE, the receiving sides ANS of the samplers PN can be moved into the sediment areas SB and out of these again. The traversing device VE can turn manually or by motor (also automatically), for example via a single bidirectional cable BSZ, which acts on the support TE, are operated.

Furthermore, in the 1A next to the sampling device PNG a benthic chamber BK shown, which is parked on the waterbed GB. Due to its ground clearance, it penetrates into the sediment area SB. By means of a stirrer RUH, a circulating flow can be generated in the benthic chamber BK, which has an influence on the exchange processes in the sediment area SB. These can be detected by means of the PNG sampling device by sampling the PN by their lateral extension the sediment area SB below the benthic chamber BK, without thereby destroying the body of water GB in the benthic chamber BK and the exchange processes are influenced at the interface water / sediment , In addition, water samples WP for comparison measurements can be obtained in the benthic chamber BK via harbors SA.

The PN samplers used are miniaturized filter tubes, so-called "Rhizon soil moisture samplers", cf. 2 , These are commercially available, but are not intended for use on the PNG sampling device to unsaturated, but saturated with water soils. According to the 2 from the prior art, there is a sampler PN on its receiving side ANS for the pore water PW from a hydrophilic microporous plastic tube KS (polymer tube, for example, length 5 cm or 10 cm, diameter 2.2 mm, pore size 0.2 microns), with a support rail SS is stabilized. This may be a stiffening wire made of metal or plastic. On the delivery side ABS for the pore water PW, the sampler has a PVC hose PVCS, via which it is connected, for example, via a connector VB with an injection syringe IS as a suction device ASV with integrated storage device LV. Silicone connecting hoses VSS can be used to connect extension hoses VLS to the PVC hose PVCS.

In the 3 By way of example, two chloride profiles (chloride in mmol / l over the sediment depth in cm) and two silicate profiles (silica in μmol / l above the sediment depth in cm) are shown, which can be compared with the site - modified sampling device PNG at the same point in a sediment area SB of a waterbody GB the times A and B have been sampled. Significantly, the time-dependent changes in the curves can be seen, which suggest appropriate exchange processes.

A, B

timings

SECTION

discharge side

ANS

Up side

ASV

suction

BK

benthic chamber

BSZ

bidirectional cable

GB

sea bed

IS

syringe

KS

Plastic tube

LV

bearing device

PN

samplers

PNG

Sampling device

PVCS

PVC tubing

PW

pore water

RO

tube

RUH

stirrer

SA

hunt

SB

sedimentary area

SG

casing

SS

support rail

SSS

front

TE

support means

TEL

supporting member

VB

Interconnects

VE

traversing

VEL

Verfahrelemente

VLS

extension hose

VSS

connecting hose

WP

water sample

Claims (10)

Sampling device for the simultaneous collection of pore water from adjacent aquatic sediment areas with a plurality of miniaturized samplers arranged in a housing with a hydrophilic microporous plastic tube on the receiving side for the pore water with a support rail and on the discharge side for the pore water with a suction device and a Storage device is connected, characterized in that the samplers (PN) vertically above one another in a support device (TE) in a blade-like housing (SG) with a vertical narrow end face (SSS) and are connected to a traversing device (VE), in which the Sampler (PN) with their receiving side (ANS) in the narrow end face (SSS) from the blade-like housing (SG) in the sediment areas (SB) are horizontally extended and retracted stored. Sampling device according to claim 1, characterized in that the carrying device (TE) for each sampler (PN) has a supporting element (TEL) and for each Support element (TEL) a separately operable movement element (VEL) is provided in the traversing device (VE). Sampling device according to claim 2, characterized in that each support element (TEL) as a tube (RO) is formed, which firmly connected to the support device (TE) is and takes up the sampler (PN) in the retracted state, and each traversing element (VE) one fixed to the sampler (PN) connected angle rail and a bidirectional cable (BSZ) having. Sampling device according to claim 1, characterized in that the carrying device (TE) firmly connected to all samplers (PN) and traversable is trained Sampling device according to one of the claims 1 to 4, characterized in that the displacement device (VE) or each traversing element (VEL) a bidirectional cable (BSZ) having. Sampling device according to one of claims 1 to 5, characterized in that the support rail (SS) of the sampler (PN) as a support wire made of stainless steel or plastic. Sampling device according to one of the claims 1 to 6, characterized in that the suction device (ASV) for each Sampler (PN) a separately actuated suction element (IS) having. Sampling device according to one of the claims 1 to 6, characterized in that the suction device (ASV) is assigned to all samplers (PN) together. Sampling device according to one of the claims 1 to 8, characterized in that the sampler (PN) as Rhizon soil moisture sampler are formed. Application of a sampling device for simultaneous collection pore water from adjacent aquatic sediment areas with several, in a housing arranged in a row miniaturized samplers with a hydrophilic microporous Plastic hose on the receiving side for the pore water with a support rail and on the submission page for the pore water with a suction device and a storage device is connected, in particular according to one of claims 1 to 9, characterized in that an in-situ use next to a settled on a waterbed (GB) Benthic chamber (BK) with such a distance is done to that the samplers (PN) in the sediment area (SB) below the Benthic chamber (BK) are extendable.