ESTURINE WETLAND SEDIMENT COLUMN SAMPLING APPARATUS AND METHOD

Description

CROSS-REFERENCE TO RELATED APPLICATION

This patent application claims the benefit and priority of Chinese Patent Application No. 202411570538.6 filed with the China National Intellectual Property Administration on Nov. 5, 2024, the disclosure of which is incorporated by reference herein in its entirety as part of the present application.

TECHNICAL FIELD

The present disclosure belongs to the technical field of wetland sample collection, and specifically relates to an estuarine wetland sediment column sampling apparatus and method.

BACKGROUND

Estuarine wetlands are transitional zones where rivers, oceans and land meet, with active sedimentation/erosion processes, and are typical fragile ecosystems and ecological hotspots of great concern to the international community. The dense estuaries and significant differences in ecological characteristics of wetlands in the eastern part of China play an important role in maintaining biodiversity, improving water quality and sequestering carbon, and are important barriers to national ecological security. However, there are ecological problems such as water-sand anomalies and degradation of native vegetation, which seriously affect the regional sustainable development based on coordinated ecology, resources and socio-economic. It is of great theoretical significance to study the evolution process and degradation mechanism of important estuarine wetlands in the eastern part of China. However, the complex and varied topography and geomorphology, the active water and salt movement process and the high habitat heterogeneity of estuarine wetlands pose a great challenge to the collection of sediment column samples from the estuarine wetlands.

At present, there are two main problems in the commonly used wetland sediment column sampling: firstly, it is mostly applied to marsh and lake wetlands with shallow water levels or static water surfaces, and it is difficult to collect sediment column samples effectively in rushing-current estuarine wetlands due to its inability to be fixed; secondly, a common gravity sampler, with an inside diameter of 58 mm or 84 mm, has a small sampling volume. Due to the high habitat heterogeneity of estuarine wetlands, it is difficult for most sediment column sampling apparatuses to collect sediment column samples with a diameter of 90 mm-100 mm and a length of 1.7 m-2 m within a water depth of 0 m-7.7 m. A column sampler track system is difficult to be promoted due to the high price because it needs to be equipped with a specialized research vessel for operation.

Thus, there is a need to develop an inexpensive sampling apparatus suitable for estuarine wetlands and capable of collecting sediment column samples with a diameter of 90 mm-100 mm and a length of 1.7 m-2 m within a water depth of 0 m-7.7 m, for smoothly collecting sediment column samples from the estuarine wetlands. Moreover, the sampling apparatus is required to collect sediment column samples having the expected length and diameter in a controlled manner to meet the experimental requirements.

SUMMARY

In order to solve the technical problem of collecting sediment column samples in a rushing-current estuarine wetland in a convenient and economical manner at a water depth of 6 m-7.7 m below a water surface and smoothly, easily, intelligently and controllably sampling estuarine wetland sediments, the present disclosure provides an estuarine wetland sediment column sampling apparatus and method, which enables smooth collection of estuarine wetland sediment samples and significantly improves the integrity of collected samples. The apparatus achieves fast sampling within a short time during use, is detachable and assemblable, is easy to carry, and is low in manufacturing cost, which is conducive to the widespread popularization and use. The technical solution of the present disclosure is as follows:

An estuarine wetland sediment column sampling apparatus includes a controller, a drill and a stabilizing frame; where the stabilizing frame includes traction components, a drill lifting passage and a base; the traction components include first linear structures, a second linear structure, and a first ring-shaped structure on a top of the drill lifting passage, a second ring-shaped structure on the base, and a third ring-shaped structure on a top of the drill; the first linear structures pass through the first ring-shaped structure on the top of the drill lifting passage and the second ring-shaped structure on the base in sequence and is secured to the base; the drill lifting passage is arranged above the base and capable of passing through the base; the second linear structure tows the drill to lift and fall in the drill lifting passage; counterweight components are arranged on the base; the controller is connected to the drill; the controller is provided with a computer-readable storage medium, on which a computer program is stored, the computer program, when executed by a processor, implementing a method of calculation for a drilling depth Y of the drill; the method of calculation is carried out in accordance with a following Equation I:

Y = 1.0091 X ⁢ 1 + 0 . 8 ⁢ 31 ⁢ X ⁢ 2 - 0.001 X ⁢ 3 - 0.001 X ⁢ 4 + 0 . 0 ⁢ 7 ⁢ 6 Equation ⁢ I

• • where in Equation I, Y is a dimensionless value of the drilling depth with dimension of meters, X1 is a dimensionless value of a water depth during sampling with dimension of meters, X2 is a dimensionless value of a preset length of a sediment column sample with dimension of meters, X3 is a dimensionless value of a weight of the counterweight components with dimension of kilograms, and X4 is a dimensionless value of a preset diameter of the sediment column sample with dimension of millimeters.

A bottom cylinder having a through hole is arranged on the base; a middle ring is arranged in a middle position of the stabilizing frame corresponding to the bottom cylinder; an upper ring is arranged on an upper position of the stabilizing frame corresponding to the middle ring; the through hole of the bottom cylinder, a hollow circular hole of the middle ring, and a hollow circular hole of the upper ring are in positional correspondence in a vertical direction and form the drill lifting passage;

• • and preferably, the controller is connected to the drill by wiring.

The hollow circular hole of the upper ring and the hollow circular hole of the middle ring both have a bore diameter greater than a width of a widest part of the drill; and the through hole of the bottom cylinder has a bore diameter greater than an outside diameter of a sampling tube of the drill.

Several support columns are arranged upwardly on a top surface of the bottom cylinder; bottom ends of the several support columns are uniformly distributed along a circumference of the bottom cylinder; and the several support columns pass through the middle ring, top ends of the several support columns are connected to a bottom surface of the upper ring.

The base further includes several connecting bars that uniformly extend axially outwardly from a side wall of the bottom cylinder; and outer sides of the several connecting bars are connected to a base rim.

The base rim is selected from a rectangular structure or a hexagonal structure;

• • preferably, a number of the several support columns ranges from 6 to 12;
  • preferably, a number of the several connecting bars is 6;
  • preferably, the several connecting bars are cuboid in shape;
  • preferably, counterweight blocks are respectively arranged on top surfaces of three connecting bars, that are spaced apart, of the several connecting bars;
  • preferably, inclined braces are respectively arranged on top surfaces of another three connecting bars, that are spaced apart, of the several connecting bars; bottom ends of the inclined braces are connected to the connecting bars and top ends of the inclined braces are connected to the support columns;
  • and preferably, the three connecting bars provided with the counterweight blocks do not overlap with the other three connecting bars provided with the inclined braces.

Three angle irons with circular holes are uniformly arranged on a circumference of a bottom surface of the upper ring in an outward direction; distances from centers of the circular holes in the three angle irons to a center of the hollow circular hole of the upper ring are equal;

• • preferably, upright lifting eyes are respectively arranged on top surfaces of three connecting bars of the several connecting bars provided with the counterweight blocks; distances from the lifting eyes to a center of the bottom cylinder are equal;
  • preferably, a hoist ring is arranged on the top of the drill;
  • preferably, the circular holes in the angle irons, the lifting eyes of the connecting bars, and the hoist ring on the top of the drill are ring-shaped structures;
  • preferably, the hoist ring on the top of the drill is connected to a hoist via the second linear structure;
  • and preferably, the first linear structures and the second linear structure are both steel wire ropes.

The drill is an electroacoustic sampling drill;

• • preferably, gravity rings are arranged on a lower portion of the drill; and a sampling tube is connected to a lower portion of the gravity rings.

An estuarine wetland sediment column sampling test method, including: performing sediment column sampling in an estuarine wetland by using an estuarine wetland sediment column sampling apparatus.

Arranging the estuarine wetland sediment column sampling apparatus on a surface layer of sediments in the estuarine wetland; inputting the weight of the counterweight components, the water depth during sampling, the preset length of the sediment column sample and the preset diameter of the sediment column sample to the controller; and starting the estuarine wetland sediment column sampling apparatus for operation.

The present disclosure achieves the following beneficial effects.

The estuarine wetland sediment column sampling apparatus and method of the present disclosure solves the problem that sediment column sampling in an estuarine environment with complex current cannot be achieved using only drills. Besides, by constructing a metal fixing frame, an electroacoustic sediment sampling drill is disposed in the apparatus and accordingly is less prone to drifting along with water. Moreover, the counterweights are added to ensure that the entire frame is perpendicular to the sampling drill, so that sediment samples can be collected intactly. The whole sampling process, from lowering the apparatus to withdrawing the apparatus, can be completed in 10 minutes, which needs short time and is fast, avoiding the disadvantages such as long sampling time of an original column sampler track system for estuarine wetlands.

The estuarine wetland sediment column sampling apparatus and method of the present disclosure breaks the limitation that fast and convenient sampling can only be carried out in marsh and lake wetlands with shallow water levels or static water surfaces, and realizes the collection of sediment column samples in an estuarine wetland environment with rushing current and high habitat heterogeneity. The estuarine wetland sampling apparatus of the present disclosure is low in manufacturing cost, has great significance in realizing low-cost, fast and convenient collection of estuarine wetland sediment column samples, and has been practically applied in the Yangtze River Estuary, the Pearl River Estuary and the Liaohe River Estuary, which is suitable for promotion in the whole country.

As verified by sampling practice, the sampling apparatus of the present disclosure automatically calculates and controls the drilling depth of the drill according to the preset length and diameter of the sediment column sample, the water depth during sampling, and the weight of the counterweights to enable the length of the collected sediment column sample to be consistent with a preset value. Therefore, the sampling apparatus of the present disclosure can efficiently and accurately control the length of the sediment column sample collected for an experiment by presetting and calculating.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic structural diagram of an estuarine wetland sediment column sampling apparatus according to one embodiment of the present disclosure;

FIG. 2 is a schematic structural diagram of a stabilizing frame of an estuarine wetland sediment column sampling apparatus according to another embodiment of the present disclosure; and

FIG. 3 is a schematic structural diagram of a drill of an estuarine wetland sediment column sampling apparatus according to one embodiment of the present disclosure.

List of reference signs in the figures: 1 stabilizing frame (outer frame), 2 controller (internal instrument), 3 ring-shaped structure on top of drill (upper fixed disk, upper ring), 4 ring-shaped structure on top of drill lifting passage (middle fixed disk, middle ring), 5 second linear structure, 6 ring-shaped structure of base (bottom fixed ring), 7 base (bottom regular-hexagonal base), 8 first linear structure (support column, stainless steel cylinder), 9 inclined brace (stainless steel support), 10 angle iron with circular hole, 11 positioning hole, 12 base rim (rim cuboid), 13 connecting bar (connecting cuboid), 14 bottom cylinder (central ring), 15 lifting eye, 16 counterweight component (counterweight block, cylindrical counterweight), 17 drill (electroacoustic sampling drill), 18 gravity ring, 19 hoist ring, 20 sampling tube, and 21 drill lifting passage.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The detailed description of the present disclosure will be further specifically described below in conjunction with specific embodiments and the accompanying drawings, but does not thereby limit the scope of protection of the present disclosure.

Embodiments in Group 1: Estuarine Wetland Sediment Column Sampling Apparatus of the Present Disclosure

According to the embodiments in this group, provided is an estuarine wetland sediment column sampling apparatus. All the embodiments in this group have the following features. The estuarine wetland sediment column sampling apparatus includes a controller 2, a drill 17 and a stabilizing frame 1. The stabilizing frame 1 includes traction components, a drill lifting passage 21 and a base 7. The traction components include first linear structures 8, a second linear structure 5, and ring-shaped structures 4, 6, 3 arranged on the top of the drill lifting passage 21, the base, and the top of the drill 17, respectively. The first linear structures 8 pass through the ring-shaped structure 4 on the top of the drill lifting passage and the ring-shaped structure 6 on the base in sequence and is secured to the base 7. The drill lifting passage 21 is arranged above the base 7 and capable of passing through the base 7. The second linear structure 5 tows the drill 17 to lift and fall in the drill lifting passage 21. Counterweight components 16 are arranged on the base 7. The controller 2 is connected to the drill 17. The controller 2 is provided with a computer-readable storage medium, on which a computer program is stored, the computer program, when executed by a processor, implementing a method of calculation for a drilling depth Y of the drill 17; the method of calculation is carried out in accordance with a following Equation I:

Y = 1.0091 X ⁢ 1 + 0 . 8 ⁢ 31 ⁢ X ⁢ 2 - 0.001 X ⁢ 3 - 0.001 X ⁢ 4 + 0 . 0 ⁢ 7 ⁢ 6 Equation ⁢ I

In Equation I, Y is a dimensionless value of the drilling depth with dimension of meters, X1 is a dimensionless value of a water depth during sampling with dimension of meters, X2 is a dimensionless value of a preset length of a sediment column sample with dimension of meters, X3 is a dimensionless value of a weight of the counterweight components with dimension of kilograms, and X4 is a dimensionless value of a preset diameter of the sediment column sample with dimension of millimeters.

In some embodiments, there is no direct relationship between the water depth during sampling and the length of the collected sample, and it is generally accepted that the greater the water depth, the more difficult it is to obtain samples with the same length as compared to shallow waters.

In some embodiments, a bottom cylinder 14 having a through hole is arranged on the base 7; a middle ring 4 is arranged in a middle position of the stabilizing frame corresponding to the bottom cylinder 14; an upper ring 3 is arranged on an upper position of the stabilizing frame corresponding to the middle ring 4; the through hole of the bottom cylinder, a hollow circular hole of the middle ring 4, and a hollow circular hole of the upper ring 3 are in positional correspondence in a vertical direction and form the drill lifting passage 21.

The ring-shaped structure 4 (middle fixed disk, middle ring) on the top of the drill lifting passage refers to two disks arranged in the middle. The disks are provided with screw holes, so that the upper and lower disks can be secured by means of screws.

In a specific embodiment, the hollow circular hole of the upper ring 3 and the hollow circular hole of the middle ring 4 both have a bore diameter greater than a width of a widest part of the drill; and the through hole of the bottom cylinder 14 has a bore diameter greater than an outside diameter of a sampling tube of the drill 17.

In some embodiments, several support columns 8 are arranged upwardly on a top surface of the bottom cylinder 14; bottom ends of the several support columns 8 are uniformly distributed along a circumference of the bottom cylinder 14; and the several support columns 8 pass through the middle ring 4, top ends of the several support columns are connected to a bottom surface of the upper ring 3.

In a further embodiment, the base 7 is further provided with several connecting bars 13 that uniformly extend axially outwardly from a side wall of the bottom cylinder 14; and outer sides of the several connecting bars 13 are connected to a base rim 12.

In a preferred embodiment, one end of the connecting bar 13 is connected to the bottom cylinder 14 and the other end of the connecting bar is connected to the base rim 12.

In a specific embodiment, the base rim 12 is selected from a rectangular structure or a hexagonal structure.

In some embodiments, in other wetlands such as lake or coastal wetlands where the water current is not as turbulent as the water current in an estuarine wetland, the base rim 12 may be constructed in a rectangular structure, such as a square or rectangular structure, which can accomplish the sample collection; and in the rushing-current wetland such as the estuarine wetland, a more stable hexagonal base structure may be used.

Preferably, the number of the several support columns 8 is 6-12.

Preferably, the number of the connecting bars 13 is 6.

Preferably, the connecting bars 13 are cuboid in shape.

Preferably, counterweight blocks are respectively arranged on top surfaces of three connecting bars 13 that are spaced apart.

Preferably, inclined braces 9 are respectively arranged on top surfaces of another three connecting bars 13 that are spaced apart; bottom ends of the inclined braces 9 are connected to the connecting bars 13 and top ends of the inclined braces are connected to the support columns 8.

Preferably, the three connecting bars 13 provided with the counterweight blocks do not overlap with the other three connecting bars 13 provided with the inclined braces 9.

In some embodiments, three angle irons 10 with circular holes are uniformly arranged on a circumference of the bottom surface of the upper ring 3 in an outward direction; distances from the centers of the circular holes in the three angle irons to the center of the hollow circular hole of the upper ring are equal.

Preferably, upright lifting eyes 15 are respectively arranged on the top surfaces of the three connecting bars 13 provided with the counterweight blocks 16; and distances from the lifting eyes 15 to the center of the bottom cylinder 14 are equal.

One of functions of the stabilizing frame formed by the base 7, the drill lifting passage 21, the support columns 8, the connecting bars 13, the counterweight blocks 16 and the like is to stabilize a drill instrument by means of the counterweights and a symmetrical structure adapted to the drill instrument to prevent the drill instrument falling down in the rushing current. However, the smooth collection of samples in the rushing current is mainly related to the following factors: (1) a stable hexagonal base structure, which is less prone to tilt or asymmetry, is also one of the important factors to ensure vertical stability of the drill instrument; (2) the height of the stabilizing frame is also critical to ensure the smooth collection of samples: a sediment column sample of 2 m needs to be collected; if the stabilizing frame is too short, it will not be able to collect continuous samples at the desired depth; if the stabilizing frame is too long, firstly, the height of a boom is required to be high enough and the apparatus cannot be lifted in the case of the boom being too short, and secondarily, the lower end of the sampling tube cannot be jammed at the edge of the positioning hole and will be shifted; therefore, the well matching between the height of the stabilizing frame and the length of a built-in device is also the key to the smooth collection of the samples; (3) the entire apparatus has a weight controlled at 155 kg, which can withstand a rushing current of a complex estuarine environment and can ensure the apparatus being vertical; and it can also ensure that the weight before and after sampling is not too heavy, avoiding situations in which the boom cannot lift or is difficult to transport. Reasonable control of the weight of the apparatus is a key factor in meeting the requirements of collecting samples in the rushing current and facilitating the actual operation.

If the base of this stabilizing frame is changed to a base in other shapes such as square or rectangle, the number of support columns is increased or decreased, and the weight of the counterweight blocks is ensured, the collection of samples can still be successfully achieved in lake wetlands and other coastal wetlands where the water current is not as turbulent as that of estuarine wetlands. However, it is recommended that a more stable hexagonal base structure be used in a rushing-current environment such as estuarine wetlands.

The collection of samples within a water depth of 0 m-7.7 m by means of the sampling apparatus according to one embodiment of the present disclosure is the problem that can be solved by the apparatus of the present disclosure and is the limit of deep-sea sampling.

The sampling apparatus of the present disclosure enables the sample collection within a water depth of 0 m-7.7 m. The sampling within the water depth of 0 m-7.7 m is mainly implemented by overcoming the following difficulties: (1) the entire apparatus is able to be lowered vertically, enter the water, and collect intact and continuous samples in an estuarine wetland environment with rushing current; (2) the height of the apparatus is reasonably designed such that the apparatus can be lifted and lowered fully by the boom, ensuring the collection of sediment samples at a depth of 2 m.

The drill instrument is moved up and down inside the stabilizing frame. The apparatus is provided with the gravity rings and the positioning hole, and the diameter of the gravity ring is slightly smaller than the diameter of the frame, which ensures that the drill instrument will not shift too much to move out of the stabilizing frame when moved up and down during working of the drill instrument. The positioning hole strengthens the fixation, and the lower end of the sampling tube can be jammed at the edge of the positioning hole to prevent the drill instrument or its sampling tube from shifting to the outside of the stabilizing frame due to the vibration when the drill instrument is moved up and down.

Preferably, a hoist ring 19 is arranged on the top of the drill 17.

Preferably, the circular holes in the angle irons 10, the lifting eyes 15 of the connecting bars, and the hoist ring 19 on the top of the drill are the ring-shaped structures.

Preferably, the hoist ring 19 on the top of the drill is connected to a hoist (not shown) via the second linear structure 5.

Preferably, the first linear structures 8 and the second linear structure 5 are both steel wire ropes.

The first linear structures 8 and the second linear structure 5 are respectively configured for lifting the entire sampling apparatus that includes the stabilizing frame 1 and the drill 17 and placing the sampling apparatus in a suitable sampling position by means of the hoist.

In a specific embodiment, the drill 17 is an electroacoustic sampling drill.

Preferably, gravity rings 18 are arranged on a lower portion of the drill 17; and a sampling tube 20 is connected to a lower portion of the gravity rings 18.

Embodiments in Group 2: Estuarine Wetland Sediment Column Sampling Test Method of the Present Disclosure

According to the embodiments in this group, provided is an estuarine wetland sediment column sampling test method of the present disclosure. All of the embodiments in this group have the following features: the estuarine wetland sediment column sampling apparatus according to any one of the embodiments in Group 1 is used for performing sediment column sampling in an estuarine wetland.

In a specific embodiment, the estuarine wetland sediment column sampling apparatus is arranged on a surface layer of sediments in the wetland, the weight of counterweights, the water depth during sampling, and the preset length and preset diameter of the sediment column sample are input to the controller, and the estuarine wetland sediment column sampling apparatus is started for operation.

According to a specific embodiment of the present disclosure, provided is a sediment column sampling apparatus suitable for use in an estuarine wetland, which includes an outer frame 1 for securing instruments, and an internal instrument 2. The outer frame 1 consists of four layers, including an upper fixed disk 3, middle fixed disks 4 and 5, a bottom fixed ring 6 and a bottom regular-hexagonal base 7, which are connected to twelve stainless steel cylinders 8 in the middle and three stainless steel supports 9 to form an integral frame. The upper fixed disk 3 has three angle irons 10 with circular through holes for steel wire ropes to pass through. The bottom fixed ring 6 has a positioning hole 11 in the middle for the sampling tube to pass through. The regular-hexagonal base 7 consists of a rim formed of six cuboids 12, six bottom cuboids 13 connected to a central ring 14, three lifting eyes 15 and three cylindrical counterweights 16. The rim cuboids 12, the bottom connecting cuboids 13 and the central ring 14 are welded integrally, and the cuboids 13 are connected to the bottom fixed ring 6. The three lifting eyes 15 are secured to the bottom connecting cuboids 13 and configured for hooking three steel wire ropes that pass through the circular holes of the angle irons 10. The cylindrical counterweights 16 are connected to the regular-hexagonal base 7 by means of set screws. The internal instrument 2 includes an electroacoustic sampling drill 17, gravity rings 18 (solid cylinders, which serve to increase the counterweight), a hoist ring 19 and a sampling tube 20 (the hoist ring is an original component of the drill; the gravity rings and the sampling tube are added, and are necessary components of the drill for sampling). The hoist ring 19 is configured for hooking a steel wire rope. The four steel wire ropes mentioned above may be secured to a boom or a lifting hook with a pulley, and are used for lifting the apparatus after sampling.

The central ring 14 and the bottom fixed ring 6 in FIG. 2 are not the same component. The two components are made to facilitate detachment and transport.

During sample collection, the sediment column sampling apparatus is lowered slowly via the boom. Due to the total weight of 155 kg, the apparatus can withstand the impact of the current in the complex estuarine environment and can be kept vertical. When the apparatus is lowered to the surface layer of sediments such as bottom sludge, the outer frame 1 is stationary to play a role in securing, and the inner instrument 2 continues to be lowered, thereby obtaining sediment samples continuously by means of electroacoustic vibrations. After the samples are obtained, the boom is slowly lifted and moved to level ground, the sample tube 20 is then disassembled, followed by removing of the sediment sample.

The entire apparatus has a height of 3 m. The upper fixed disk 3, the middle fixed disks 4 and 5, and the bottom fixed ring 6 all have a diameter of 60 cm. The stainless steel cylinders 8 each have a diameter of 42 mm and a height of 1.5 m. Each of the rim cuboids 12 of the bottom regular-hexagonal base 7 has a length of 87 cm, a width of 100 mm, and a height of 80 mm. The bottom connecting cuboids 13 each have a length of 45 cm, a width of 100 mm, and a height of 80 mm. The positioning hole 11 has a diameter of 110 mm. The central ring 14 has an outside diameter of 60 cm, a width of 100 mm and a height of 80 mm. The cylindrical counterweights 16 each have a diameter of 150 mm, a height of 350 mm and a weight of 25 kg. The gravity rings 18 are made of stainless steel and each have an outside diameter of 400 mm, an inside diameter of 330 mm, a height of 50 mm, and a weight of 20 kg. The apparatus can be used in a water area at a water depth within 50 m and has a sampling diameter of 90 mm-100 mm and a sampling length of 2 m.

A most specific embodiment of the present disclosure provides an estuarine wetland sediment column sampling apparatus having the following features: materials required: stainless steel disks each having a thickness of 2 cm and an outside diameter of 60 cm; stainless steel disks each having a thickness of 2 cm, an outside diameter of 60 cm, and an inside diameter of 110 mm; stainless steel cylinders each having a diameter of 42 mm and a height of 1.5 m; stainless steel supports each having a length of 1.7 m; stainless steel cuboids each having a length of 87 cm, a width of 100 mm and a height of 80 mm; stainless steel cuboids each having a length of 45 cm, a width of 100 mm and a height of 80 mm; a stainless steel ring having an outside diameter of 60 cm, a width of 100 mm and a height of 80 mm; stainless steel cylindrical counterweights each having a diameter of 150 mm, a height of 350 mm and a weight of 25 kg; an electroacoustic sampling drill; and a sampling tube having a length of 2 m and a diameter of 90 mm-100 mm.

Steps of manufacturing and sampling methods are as follows.

1. Manufacturing of the regular-hexagonal base: Six stainless steel cuboids with a length of 87 cm, six stainless steel cuboids with a length of 45 cm, and the stainless steel ring with an outside diameter of 60 cm, a width of 100 mm, and a height of 80 mm are welded together to form the bottom regular-hexagonal base of the sediment column sampling fixture.

2. Manufacturing of cylinders: Top ends and bottom ends of six stainless steel cylinders each having a diameter of 42 mm and a height of 1.5 m are respectively welded to the stainless steel disks each having a thickness of 2 cm and an outside diameter of 60 cm to form an upper cylinder of the apparatus. Top ends of other six stainless steel cylinders each having a diameter of 42 mm and a height of 1.5 m are welded to the stainless steel disk with a thickness of 2 cm and an outside diameter of 60 cm, while bottom ends of the other six stainless steel cylinders are welded to the stainless steel disk with a thickness of 2 cm, an outside diameter of 60 cm and an inside diameter of 110 mm, to form a lower cylinder of the apparatus.

3. Assembling of the apparatus: The lower cylinder is secured to the regular-hexagonal base, and three stainless steel supports are connected between the lower cylinder and the regular-hexagonal base, thereby playing a role in reinforcement. Three stainless steel cylindrical counterweights are mounted on the regular-hexagonal base. The upper cylinder and the lower cylinder are fixedly connected together.

The electroacoustic sampling drill is placed into the assembled cylinder apparatus through the stainless steel disk on the top, the gravity rings are sleeved on the periphery of the drill, and the sampling tube is mounted on the bottom of the drill. Three steel wire ropes pass through the circular holes of the angle irons at the top of the cylinder apparatus, and hook three lifting eyes on the regular-hexagonal base. The hoist ring at the top of the electroacoustic sampling drill is hooked with a steel wire rope. The four steel wire ropes are secured to the boom hook.

4. Sampling method: During sampling, the sediment column sampling apparatus is lowered slowly by the boom. When the apparatus is lowered to the surface layer of sediments such as bottom sludge, the outer frame 1 is stationary to play a role in securing and the inner instrument 2 continues to be lowered, thereby obtaining sediment samples continuously by means of electroacoustic vibrations. The apparatus is stopped lowering when the sampling tube is fully immersed by vibrations. At this time, the boom is lifted slowly, the inner instrument 2 is first lifted into the outer frame 1, and then the inner instrument 2 and the outer frame 1 are lifted out of the water surface together and moved to the level ground, followed by detaching the sampling tube and removing the sediment sample. In some other embodiments, the sampling method includes that the estuarine wetland sediment column sampling apparatus is arranged on a surface layer of sediments in the wetland, the weight of counterweights (balanced and measured in advance), the water depth during sampling (measured by the ship's own water depth sounder), and the preset length of the sediment column sample are input to the controller, and the estuarine wetland sediment column sampling apparatus is started for operation.

Experimental Examples: Verification of Accuracy of Controllable Sampling by the Sampling Apparatus of the Present Disclosure

Seventeen sediment column samples with a length of 1.0 m-1.7 m and a diameter of 90 mm-100 mm within a water depth of 0.1-7.7 m were collected in the Liaohe River Estuary, the Yellow River Estuary, the Yangtze River Estuary, and the Pearl River Estuary, respectively, by using the sampling apparatus according to a specific embodiment of the present disclosure. The sampling apparatus was placed on the sediment surface below the water depth, followed by presetting, before the operation, the length of the expected sample to be collected, obtaining data of water depth by means of the ship's own water depth sounder, and measuring weight data of the counterweights balanced in advance. The three data values were processed dimensionlessly and then input to the controller, and the controller calculated and controlled the drilling depth of the drill such that the drill works to collect the sediment column sample. The length and diameter of the collected sediment column samples were then measured to obtain measured values. The specific comparison is shown in Table 1 below:

The preset values and the measured values of the length and diameter in Table 1 above are entered into SPSS for significance analysis of difference, respectively, where the p-value between the preset values and the measured values is less than 0.05 and the difference is insignificant, which is sufficient to show that the sampling apparatus of the present disclosure has high accuracy in controllability of the length of the collected samples.

The words such as “upper”, “lower”, “left”, “right”, “front”, “back” used herein to describe orientations are for the convenience of illustration based on orientations shown in the figures in the accompanying drawings, and in the actual apparatus, these orientations may be different due to the way the apparatus is placed.

It will be clear that above embodiments of the present disclosure are merely examples given for the purpose of clearly illustrating the present disclosure and are not intended to limiting the embodiments of the present disclosure. For those of ordinary skill in the art, other variations or changes in different forms may be made on the basis of the above description. It is not possible to exhaust all of the embodiments herein. Any obvious changes or variations derived from the technical solutions of the present disclosure are still within the scope of protection of the present disclosure.