A seabed microplastic sampling device and method

Abstract

The present application relates to the technical field of microplastic sampling device, and discloses a seabed microplastic sampling device and method, which comprises a multi-point sampling cylinder, which is symmetrically arranged on the two sides of a central connecting framework, and each multi-point sampling cylinder is sequentially provided with a surface layer sampling mechanism, a middle layer sampling mechanism and a deep layer sampling mechanism along the axial direction, wherein the multi-point sampling cylinders are symmetrically arranged on the two sides of the central connecting framework, the multi-point sampling cylinders on the two sides synchronously perform the same sampling action at the same sampling point, and two groups of independent samples are respectively collected, which are used for mutual comparison.The design can effectively eliminate the accidental error caused by single sampling, provide parallel samples for subsequent laboratory analysis, and significantly improve the reliability and statistical significance of data.

Description

Technical Field

[0001] This invention relates to the field of microplastic sampling device technology, specifically to a seabed microplastic sampling device and method. Background Technology

[0002] With the increasing severity of marine plastic pollution, microplastics, as a new type of pollutant with a particle size of less than 5 millimeters, have become a major focus of global marine environmental research. After entering the ocean, microplastics gradually settle under physical, chemical, and biological processes, eventually accumulating in large quantities in seabed sediments. Studies have shown that the abundance of microplastics in seabed sediments is much higher than in surface seawater, making seabed sediments a significant sink for microplastics. Accurately obtaining data on the occurrence of microplastics in seabed sediments is of fundamental importance for assessing their ecological risks, revealing migration patterns, and formulating control strategies.

[0003] Currently, sampling for seabed microplastics mainly relies on traditional sediment sampling equipment such as box samplers, multi-tube samplers, and grab samplers. These devices have several limitations in practical applications: First, most samplers are designed for single-point sampling, acquiring only one set of samples per deployment, lacking parallel controls, making it difficult to effectively eliminate the influence of random errors on the analysis results, and resulting in insufficient data reliability; second, limited by the number and structure of sampling tubes, existing equipment can usually only collect sediments from the surface or a single depth, making it difficult to simultaneously acquire samples from different layers in a single deployment, thus failing to meet the needs of microplastic vertical distribution research.

[0004] Therefore, there is an urgent need to provide a seabed microplastic sampling device that can achieve multi-point synchronous control sampling, multi-level vertical profile synchronous acquisition, and minimal disturbance to the seabed microplastic layer, in order to solve the problems of poor data reliability, low sampling efficiency, and easy sample distortion caused by existing sampling equipment. Summary of the Invention

[0005] The purpose of this invention is to provide a seabed microplastic sampling device to solve the problems mentioned in the background art.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a seabed microplastic sampling device, comprising:

[0007] The multi-point sampling tubes are arranged in a mirror-symmetrical manner on both sides of the central connecting frame. Each multi-point sampling tube contains a surface sampling mechanism, a middle sampling mechanism, and a deep sampling mechanism arranged sequentially along the axial direction. The surface sampling mechanism, the middle sampling mechanism, and the deep sampling mechanism are used to collect seabed surface sediment, middle sediment, and deep sediment samples, respectively. The multi-point sampling tubes on both sides are arranged in a mirror-symmetrical manner to collect two sets of samples simultaneously at the same sampling point for mutual control.

[0008] The central connecting frame is fixedly connected between the two multi-point sampling tubes to maintain a fixed relative distance between the two multi-point sampling tubes. The central connecting frame is also equipped with a flow guiding and deceleration mechanism to slow down the sinking speed during the sinking process of the device.

[0009] An adaptive counterweight mechanism is movably mounted on the central connecting frame. The adaptive counterweight mechanism dynamically adjusts the overall counterweight of the device in response to the device's status information.

[0010] A sensor array is mounted on the central connecting frame or the multi-point sampling tube. The sensor array includes a depth sensor, an attitude sensor, and an altimeter. The depth sensor is used to detect the water depth where the device is located, the attitude sensor is used to detect the tilt angle of the device, and the altimeter is used to detect the height of the device from the seabed.

[0011] According to the above technical solution, the multi-point sampling tube has a hollow cylindrical structure. The surface sampling mechanism is located at the center of the multi-point sampling tube and is driven to extend and retract by a first electric telescopic cylinder. The middle-layer sampling mechanism and the deep-layer sampling mechanism are evenly distributed around the periphery of the surface sampling mechanism along the circumference, and the middle-layer sampling mechanism and the deep-layer sampling mechanism are alternately arranged in the circumference. The middle-layer sampling mechanism and the deep-layer sampling mechanism are driven to extend and retract by a second electric telescopic cylinder, respectively.

[0012] According to the above technical solution, the surface sampling mechanism includes:

[0013] The first electric telescopic cylinder is fixedly installed in the center of the multi-point sampling tube;

[0014] The central telescopic cylinder has a hollow cylindrical structure and is installed through the center of the multi-point sampling cylinder. One end of the central telescopic cylinder is fixedly installed on the telescopic end of the first electric telescopic cylinder, and the other end of the central telescopic cylinder is provided with multiple first sampling ports in the circumferential direction.

[0015] The first suction assembly is disposed inside the central telescopic cylinder. The first suction assembly consists of a third electric telescopic cylinder and a first piston. The third electric telescopic cylinder is fixedly installed inside the central telescopic cylinder, and the first piston is fixedly installed at the telescopic end of the third electric telescopic cylinder. The side wall of the first piston is in sliding sealing cooperation with the inner wall of the central telescopic cylinder.

[0016] According to the above technical solution, the middle-layer sampling mechanism and the deep-layer sampling mechanism have the same structure, both including:

[0017] The second electric telescopic cylinder is fixedly installed at the inner edge of the multi-point sampling tube;

[0018] The edge telescopic cylinder has a hollow cylindrical structure. One end of the edge telescopic cylinder is cone-shaped. The edge telescopic cylinder is disposed through the edge of the multi-point sampling cylinder. One end of the edge telescopic cylinder is fixedly installed on the telescopic end of the second electric telescopic cylinder. The other end of the edge telescopic cylinder has multiple second sampling ports circumferentially opened on its side wall.

[0019] The second suction assembly is disposed inside the edge telescopic cylinder. The second suction assembly consists of a fourth electric telescopic cylinder and a second piston. The fourth electric telescopic cylinder is fixedly installed inside the edge telescopic cylinder, and the second piston is fixedly installed at the telescopic end of the fourth electric telescopic cylinder. The side wall of the second piston is in sliding sealing cooperation with the inner wall of the edge telescopic cylinder.

[0020] According to the above technical solution, the central connecting frame includes:

[0021] An I-beam connecting beam is horizontally positioned between two multi-point sampling tubes. The I-beam connecting beam consists of a central crossbeam and horizontal connecting beams located at both ends of the central crossbeam. The ends of the horizontal connecting beams are respectively fixedly installed on the side walls of the corresponding multi-point sampling tubes.

[0022] The bottom support is fixedly installed below the I-beam connecting beam. The bottom support consists of a vertical support rod and a bottom buffer. The bottom buffer is located directly below the I-beam connecting beam. The vertical support rod is mirror-symmetrically arranged between the central crossbeam and the bottom buffer.

[0023] The bottom buffer consists of a first rubber pad with a straight groove and a second rubber pad symmetrically arranged on the side wall of the first rubber pad. The first rubber pad is located directly below the I-beam connecting beam, and the second rubber pads are respectively arranged below the multi-point sampling cylinder.

[0024] According to the above technical solution, the flow guiding and deceleration mechanism includes:

[0025] Swirl blades are arranged in a linear array on the surface of the horizontal connecting beam along the length of the horizontal connecting beam;

[0026] A flow stabilizing hole is formed through the horizontal connecting beam, and each flow stabilizing hole is respectively disposed between two adjacent swirl blades;

[0027] Electromagnets are evenly distributed at the lower end of the horizontal connecting beam;

[0028] A magnetic suction plate is attached to the lower end of the horizontal connecting beam to block the swirl vane and the flow stabilizing hole.

[0029] A connecting rope is provided on the side wall of the horizontal connecting beam. One end of the connecting rope is fixedly connected to the horizontal connecting beam, and the other end of the connecting rope is fixedly connected to the magnetic suction plate, for recycling after the magnetic suction plate is detached.

[0030] According to the above technical solution, the adaptive counterweight mechanism includes:

[0031] The adaptive counterweight box has a hollow cavity inside. The adaptive counterweight box is symmetrically fixed with lifting sliding blocks, which are slidably installed on the corresponding vertical support rods. The adaptive counterweight box has a top flow port and a bottom flow port at the center of the top and bottom, respectively.

[0032] Displacement limiting blocks are fixedly installed at the top and bottom of each of the vertical support rods to limit the sliding stroke of the adaptive counterweight box along the vertical support rods;

[0033] A central control mechanism is located in the center of the adaptive counterweight box to control the opening and closing of the top and bottom flow ports.

[0034] According to the above technical solution, the central switching mechanism includes:

[0035] A hollow waterproof cylinder is located in the center of the self-adaptive counterweight box. Side wing fixing rods are fixedly installed on both sides of the hollow waterproof cylinder, and the ends of the side wing fixing rods are fixedly installed on the inner wall of the self-adaptive counterweight box.

[0036] The vertical moving part is installed through the hollow waterproof cylinder. The vertical moving part consists of a plurality of vertical moving rods evenly distributed around the circumference and circular plates fixedly installed at the ends of each of the vertical moving rods.

[0037] A piston rod, one end of which is fixedly mounted on the corresponding circular plate, and a conical piston head fixedly mounted on the end of the piston rod. The top flow port and the bottom flow port are both inverted conical orifices adapted to the conical piston head. The conical piston head is movably disposed above the corresponding top flow port and bottom flow port, respectively, for sealing or opening the corresponding flow ports.

[0038] The fifth electric telescopic cylinder is fixedly installed inside the hollow waterproof cylinder. A movable plate is fixedly installed at the output end of the fifth electric telescopic cylinder. The side wall of the movable plate is fixedly connected to each of the vertical movable rods through a diverging rod.

[0039] According to the above technical solution, a delayed release mechanism is further provided between the circular plate at the bottom and the corresponding piston rod, the delayed release mechanism comprising:

[0040] A delayed release cylinder is fixedly installed on the circular plate located at the bottom. The interior of the delayed release cylinder is hollow, and one end of the piston rod located at the bottom extends into the interior of the delayed release cylinder.

[0041] A limiting plate is fixedly installed at the end of the piston rod, and the limiting plate is slidably disposed inside the delayed release cylinder;

[0042] A telescopic spring is disposed inside the delayed release cylinder. One end of the telescopic spring abuts against the limiting plate, and the other end of the telescopic spring abuts against the inner wall of the delayed release cylinder.

[0043] A sampling method for a seabed microplastic sampling device includes the following steps:

[0044] S1. Device lowering and attitude monitoring

[0045] The seabed microplastic sampling device is hoisted from the mother ship to the target sea area. The sensor group monitors the sinking depth, tilt angle and height above the seabed of the device in real time, and transmits the collected status information to the control system.

[0046] S2, Bottom Contact Buffer

[0047] When the altimeter detects that the device is approaching the seabed, the flow guiding and deceleration mechanism guides and decelerates the surrounding water flow to reduce the sinking speed of the device; after the device touches the bottom, the bottom buffer provides initial cushioning and support for the device.

[0048] S3, Adaptive Weight Loading and Attitude Stabilization

[0049] After the device touches the bottom, the control system drives the fifth electric telescopic cylinder to operate. Under the action of the delayed release mechanism, the top flow port opens first, and seawater enters the adaptive counterweight box from the top. The bottom flow port remains closed to avoid generating eddies at the bottom that disturb the microplastic layer. After the delay is completed, the bottom flow port opens, and seawater smoothly fills the adaptive counterweight box. The control system then drives the fifth electric telescopic cylinder to reverse its action, simultaneously sealing and closing the top and bottom flow ports, increasing the device's weight, and making the device stable on the seabed.

[0050] S4, Surface Sampling

[0051] The first electric telescopic cylinder drives the central telescopic cylinder to extend, so that the central telescopic cylinder is inserted into the seabed surface sediments. The third electric telescopic cylinder drives the first piston to slide along the inner wall of the central telescopic cylinder and draw surface sediment samples through the first sampling port.

[0052] S5, Mid-layer Sampling

[0053] The second electric telescopic cylinder of the middle layer sampling mechanism drives the corresponding edge telescopic cylinder to extend, so that the edge telescopic cylinder is inserted into the middle layer sediments on the seabed. The corresponding fourth electric telescopic cylinder drives the second piston to slide along the inner wall of the edge telescopic cylinder and draws the middle layer sediment sample through the corresponding second sampling port.

[0054] S6, Deep Sampling

[0055] The second electric telescopic cylinder of the deep sampling mechanism drives the corresponding edge telescopic cylinder to extend, so that the edge telescopic cylinder is inserted into the deep seabed sediment. The corresponding fourth electric telescopic cylinder drives the second piston to slide along the inner wall of the edge telescopic cylinder, and draws deep sediment samples through the corresponding second sampling port.

[0056] S7, Sample Recovery

[0057] Each sampling unit retracts sequentially into the multi-point sampling tube, and the seabed microplastic sampling device is retrieved to the mother ship. Surface sediment samples, mid-layer sediment samples, and deep sediment samples are then taken out and preserved.

[0058] Compared with the prior art, the beneficial effects achieved by the present invention are:

[0059] (1) Mirror-symmetric multi-point sampling, high data reliability

[0060] This invention employs a mirror-symmetrical arrangement of multi-point sampling tubes on both sides of a central connecting frame. The two tubes simultaneously perform identical sampling actions at the same sampling point, collecting two independent sets of samples for mutual comparison. This design effectively eliminates random errors that may arise from single sampling, providing parallel samples for subsequent laboratory analysis, significantly improving data reliability and statistical significance, and solving the problem of traditional single-point sampling's inability to perform on-site parallel comparisons.

[0061] (2) A single deployment can achieve complete vertical profile acquisition, greatly improving work efficiency.

[0062] This invention integrates surface sampling, mid-layer sampling, and deep-layer sampling mechanisms sequentially along the axial direction within each multi-point sampling tube. A single deployment of the device can simultaneously acquire sediment samples from the surface, mid-layer, and deep seabed layers, eliminating the need for repeated deployments. Furthermore, the mid-layer and deep-layer sampling mechanisms are alternately arranged circumferentially, each possessing an independent edge telescopic tube and driven independently by its own second electric telescopic cylinder. The two sampling layers operate without interference, and the sampling depth is precisely controllable, significantly improving the time efficiency and sample acquisition integrity of deep-sea sampling operations.

[0063] (3) Triple buffer protection effectively avoids impact damage to the seabed microplastic layer.

[0064] This invention constructs a triple-buffering protection mechanism throughout the entire process from sinking to bottom contact: the first layer is a flow-guiding and deceleration mechanism, which actively reduces the sinking speed by increasing water flow resistance through swirl vanes and balancing water pressure differences through flow-stabilizing orifices as the device approaches the seabed; the second layer is a bottom buffer component, where the first and second rubber pads absorb impact energy through elastic deformation upon bottom contact; the third layer is pre-filled air in an adaptive counterweight box, which absorbs part of the impact kinetic energy. The synergistic effect of these three buffers effectively avoids severe impacts and disturbances to the microplastic layer on the seabed surface, ensuring the in-situ representativeness of the samples.

[0065] (4) Water injection increases weight and stabilizes the bottom, ensuring reliable execution of the sampling action.

[0066] This invention increases the overall weight of the device by filling an adaptive counterweight box with water, thus stabilizing the device on the seabed. The added counterweight provides sufficient downforce and reaction force to support the subsequent insertion of the surface, mid-layer, and deep-layer sampling mechanisms, ensuring that the central and edge telescopic cylinders can be smoothly inserted into sediment layers at different depths and complete the suction sampling. This design is particularly suitable for seabed environments with bottom currents or hard sediments, effectively preventing device displacement or capsizing during sampling.

[0067] (5) Delayed counterweight loading to eliminate bottom disturbance

[0068] This invention incorporates a delayed release mechanism within the adaptive counterweight system. During the counterweight loading process after the device bottoms out, the top flow port is opened preferentially, while the bottom flow port opens with a delay. Seawater enters the adaptive counterweight box only from the top, while the bottom flow port remains closed due to the delayed release mechanism. This completely prevents eddies or jets from being generated at the bottom, thus avoiding any scouring or disturbance to the microplastic layer on the seabed surface. Once the water pressure inside the box has reached equilibrium, the bottom flow port opens again, allowing the seawater to fill smoothly, achieving zero-disturbance counterweight loading of the seabed microplastic layer. Attached Figure Description

[0069] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0070] Figure 1 This is a first perspective view of the present invention;

[0071] Figure 2 This is a second perspective view of the present invention;

[0072] Figure 3 This is a third perspective view of the present invention;

[0073] Figure 4 This is a fourth perspective schematic diagram of the present invention;

[0074] Figure 5 This is a first partial three-dimensional schematic diagram of the present invention;

[0075] Figure 6 This is a second partial perspective view of the present invention;

[0076] Figure 7 This is a third partial perspective view of the present invention;

[0077] Figure 8 This is a fourth partial perspective view of the present invention;

[0078] Figure 9 This is a fifth partial perspective view of the present invention;

[0079] Figure 10 This is the present invention. Figure 5 A magnified view of a portion of point A in the middle;

[0080] Figure 11 This is the present invention. Figure 9 A magnified view of a portion of point B in the middle;

[0081] In the diagram: 1-Multi-point sampling cylinder, 2-Surface sampling mechanism, 21-First electric telescopic cylinder, 22-Central telescopic cylinder, 221-First sampling port, 23-First suction assembly, 231-Third electric telescopic cylinder, 232-First piston, 3-Middle layer sampling mechanism, 31-Second electric telescopic cylinder, 32-Edge telescopic cylinder, 321-Second sampling port, 33-Second suction assembly, 331-Fourth electric telescopic cylinder, 332-Second piston, 4-Deep sampling mechanism, 5-Central connecting frame, 51-I-beam connecting beam, 511-Central crossbeam, 512-Horizontal connecting beam, 52-Bottom support, 521-Vertical support rod, 522-Bottom buffer, 5221-First rubber pad, 5222-Second rubber pad, 53-Guiding and deceleration mechanism, 531-Swirl vane 532-Flow stabilizing hole, 533-Electromagnet, 534-Magnetic suction plate, 535-Connecting rope, 6-Adaptive counterweight mechanism, 61-Adaptive counterweight box, 611-Top flow port, 612-Bottom flow port, 62-Lifting sliding block, 63-Displacement limiting block, 64-Central on / off mechanism, 641-Hollow waterproof cylinder, 642-Side wing fixing rod, 643-Vertical moving part, 6431-Vertical moving rod, 6432-Circular plate, 644-Piston rod, 645-Conical piston head, 646-Fifth electric telescopic cylinder, 647-Moving plate, 648-Diffusion rod, 65-Delayed release mechanism, 651-Delayed release cylinder, 652-Limiting plate, 653-Telescopic spring, 7-Sensor group, 71-Depth sensor, 72-Attitude sensor, 73-Altimeter. Detailed Implementation

[0082] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0083] Please see Figure 1-11 The present invention provides a technical solution: a seabed microplastic sampling device, comprising:

[0084] Multi-point sampling tubes 1 are arranged in a mirror-symmetrical manner on both sides of the central connecting frame 5. Each multi-point sampling tube 1 has a surface sampling mechanism 2, a middle sampling mechanism 3, and a deep sampling mechanism 4 arranged sequentially along the axial direction. The surface sampling mechanism 2, the middle sampling mechanism 3, and the deep sampling mechanism 4 are used to collect seabed surface sediment, middle sediment, and deep sediment samples, respectively. The multi-point sampling tubes 1 on both sides are arranged in a mirror-symmetrical manner to collect two sets of samples at the same sampling point simultaneously for mutual control.

[0085] The central connecting frame 5 is fixedly connected between the two multi-point sampling tubes 1 to maintain a fixed relative distance between the two multi-point sampling tubes 1. The central connecting frame 5 is also provided with a flow guiding and deceleration mechanism 53 to slow down the sinking speed during the sinking process of the device.

[0086] An adaptive counterweight mechanism 6 is movably mounted on the central connecting frame 5. The adaptive counterweight mechanism 6 dynamically adjusts the overall counterweight of the device in response to the device's status information.

[0087] Sensor group 7 is disposed on the central connecting frame 5 or the multi-point sampling tube 1. Sensor group 7 includes a depth sensor 71, an attitude sensor 72 and an altimeter 73. The depth sensor 71 is used to detect the water depth where the device is located, the attitude sensor 72 is used to detect the tilt angle of the device, and the altimeter 73 is used to detect the height of the device from the seabed.

[0088] Specifically, the multi-point sampling cylinder 1 has a hollow cylindrical structure. The surface sampling mechanism 2 is located at the center of the multi-point sampling cylinder 1 and is driven to extend and retract by the first electric telescopic cylinder 21. The middle sampling mechanism 3 and the deep sampling mechanism 4 are evenly distributed around the periphery of the surface sampling mechanism 2 in the circumferential direction, and the middle sampling mechanism 3 and the deep sampling mechanism 4 are alternately arranged in the circumferential direction. The middle sampling mechanism 3 and the deep sampling mechanism 4 are driven to extend and retract by the second electric telescopic cylinder 31, respectively.

[0089] Specifically, the surface sampling mechanism 2 includes:

[0090] The first electric telescopic cylinder 21 is fixedly installed in the center of the multi-point sampling tube 1;

[0091] The central telescopic cylinder 22 has a hollow cylindrical structure. The central telescopic cylinder 22 is disposed in the center of the multi-point sampling cylinder 1. One end of the central telescopic cylinder 22 is fixedly installed on the telescopic end of the first electric telescopic cylinder 21. The other end of the central telescopic cylinder 22 is provided with a plurality of first sampling ports 221 in the circumferential direction.

[0092] The first suction assembly 23 is disposed inside the central telescopic cylinder 22. The first suction assembly 23 consists of a third electric telescopic cylinder 231 and a first piston 232. The third electric telescopic cylinder 231 is fixedly installed inside the central telescopic cylinder 22, and the first piston 232 is fixedly installed at the telescopic end of the third electric telescopic cylinder 231. The side wall of the first piston 232 is slidably sealed with the inner wall of the central telescopic cylinder 22.

[0093] Specifically, the middle-layer sampling mechanism 3 and the deep-layer sampling mechanism 4 have the same structure, both including:

[0094] The second electric telescopic cylinder 31 is fixedly installed at the inner edge of the multi-point sampling cylinder 1;

[0095] The edge telescopic cylinder 32 has a hollow cylindrical structure. One end of the edge telescopic cylinder 32 is cone-shaped. The edge telescopic cylinder 32 is disposed through the edge of the multi-point sampling cylinder 1. One end of the edge telescopic cylinder 32 is fixedly installed on the telescopic end of the second electric telescopic cylinder 31. The other end of the edge telescopic cylinder 32 has a plurality of second sampling ports 321 circumferentially opened on the side wall.

[0096] The second suction assembly 33 is disposed inside the edge telescopic cylinder 32. The second suction assembly 33 consists of a fourth electric telescopic cylinder 331 and a second piston 332. The fourth electric telescopic cylinder 331 is fixedly installed inside the edge telescopic cylinder 32, and the second piston 332 is fixedly installed at the telescopic end of the fourth electric telescopic cylinder 331. The side wall of the second piston 332 is slidably sealed with the inner wall of the edge telescopic cylinder 32.

[0097] Specifically, the central connecting frame 5 includes:

[0098] An I-beam connecting beam 51 is horizontally positioned between two multi-point sampling tubes 1. The I-beam connecting beam 51 consists of a central crossbeam 511 and horizontal connecting beams 512 located at both ends of the central crossbeam 511. The ends of the horizontal connecting beams 512 are respectively fixedly installed on the side walls of the corresponding multi-point sampling tubes 1.

[0099] The bottom support 52 is fixedly installed below the I-beam connecting beam 51. The bottom support 52 consists of a vertical support rod 521 and a bottom buffer 522. The bottom buffer 522 is located directly below the I-beam connecting beam 51. The vertical support rod 521 is mirror-symmetrically arranged between the central crossbeam 511 and the bottom buffer 522.

[0100] The bottom buffer 522 is composed of a first rubber pad 5221 with a straight groove and a second rubber pad 5222 symmetrically arranged on the side wall of the first rubber pad 5221. The first rubber pad 5221 is located directly below the I-beam connecting beam 51, and the second rubber pads 5222 are respectively arranged below the multi-point sampling cylinder 1.

[0101] Specifically, the flow guiding and deceleration mechanism 53 includes:

[0102] Swirl blades 531 are arranged in a linear array on the surface of the horizontal connecting beam 512 along the length direction of the horizontal connecting beam 512;

[0103] A flow stabilizing hole 532 is formed through the horizontal connecting beam 512, and each flow stabilizing hole 532 is respectively disposed between two adjacent swirl blades 531;

[0104] Electromagnets 533 are evenly distributed at the lower end of the horizontal connecting beam 512;

[0105] The magnetic suction plate 534 is attached to the lower end of the horizontal connecting beam 512 and is used to shield the swirl vane 531 and the flow stabilizing hole 532.

[0106] A connecting rope 535 is provided on the side wall of the horizontal connecting beam 512. One end of the connecting rope 535 is fixedly connected to the horizontal connecting beam 512, and the other end of the connecting rope 535 is fixedly connected to the magnetic suction plate 534 for recycling after the magnetic suction plate 534 is detached.

[0107] Specifically, the adaptive counterweight mechanism 6 includes:

[0108] The adaptive counterweight box 61 has a hollow cavity inside. The adaptive counterweight box 61 is symmetrically fixedly installed with lifting sliding blocks 62. The lifting sliding blocks 62 are slidably installed on the corresponding vertical support rods 521. The adaptive counterweight box 61 has a top flow port 611 and a bottom flow port 612 respectively opened at the center of the top and bottom.

[0109] Displacement limiting blocks 63 are fixedly installed at the top and bottom of each of the vertical support rods 521, respectively, to limit the sliding stroke of the adaptive counterweight box 61 along the vertical support rods 521;

[0110] The central switching mechanism 64 is located in the center of the adaptive counterweight box 61 and is used to control the opening and closing of the top flow port 611 and the bottom flow port 612.

[0111] Specifically, the central switching mechanism 64 includes:

[0112] A hollow waterproof cylinder 641 is located in the center of the self-adaptive counterweight box 61. Side wing fixing rods 642 are fixedly installed on both sides of the hollow waterproof cylinder 641, and the ends of the side wing fixing rods 642 are fixedly installed on the inner wall of the self-adaptive counterweight box 61.

[0113] The vertical moving part 643 is disposed inside the hollow waterproof cylinder 641. The vertical moving part 643 is composed of a plurality of circumferentially distributed vertical moving rods 6431 and circular plates 6432 respectively fixedly installed at the ends of each of the vertical moving rods 6431.

[0114] A piston rod 644, one end of which is fixedly mounted on the corresponding circular plate 6432, and a conical piston head 645 is fixedly mounted on the end of the piston rod 644. The top flow port 611 and the bottom flow port 612 are both inverted conical orifices adapted to the conical piston head 645. The conical piston head 645 is movably disposed above the corresponding top flow port 611 and bottom flow port 612, respectively, for sealing or opening the corresponding flow ports.

[0115] The fifth electric telescopic cylinder 646 is fixedly installed inside the hollow waterproof cylinder 641. A movable plate 647 is fixedly installed at the output end of the fifth electric telescopic cylinder 646. The side wall of the movable plate 647 is fixedly connected to each of the vertical movable rods 6431 through a diverging rod 648.

[0116] Specifically, a delayed release mechanism 65 is further provided between the circular plate 6432 at the bottom and the corresponding piston rod 644, the delayed release mechanism 65 including:

[0117] The delayed release cylinder 651 is fixedly installed on the circular plate 6432 located at the bottom. The interior of the delayed release cylinder 651 is hollow, and one end of the piston rod 644 located at the bottom extends into the interior of the delayed release cylinder 651.

[0118] A limiting plate 652 is fixedly installed at the end of the piston rod 644, and the limiting plate 652 is slidably disposed inside the delayed release cylinder 651;

[0119] A telescopic spring 653 is disposed inside the delayed release cylinder 651. One end of the telescopic spring 653 abuts against the limiting plate 652, and the other end of the telescopic spring 653 abuts against the inner wall of the delayed release cylinder 651.

[0120] A sampling method for a seabed microplastic sampling device includes the following steps:

[0121] S1. Device lowering and attitude monitoring

[0122] The seabed microplastic sampling device is hoisted from the mother ship to the target sea area. The sensor group 7 monitors the sinking depth, tilt angle and height above the seabed of the device in real time, and transmits the collected status information to the control system.

[0123] S2, Bottom Contact Buffer

[0124] When the altimeter 73 detects that the device is approaching the seabed, the flow guiding and deceleration mechanism 53 guides and decelerates the surrounding water flow to reduce the sinking speed of the device; after the device touches the bottom, the bottom buffer 522 provides initial cushioning and support for the device.

[0125] S3, Adaptive Weight Loading and Attitude Stabilization

[0126] After the device touches the bottom, the control system drives the fifth electric telescopic cylinder 646 to operate. Under the action of the delayed release mechanism 65, the top flow port 611 opens first, and seawater enters the adaptive counterweight box 61 from the top. The bottom flow port 612 remains closed to avoid generating eddies at the bottom that disturb the microplastic layer. After the delay is completed, the bottom flow port 612 opens, and seawater smoothly fills the adaptive counterweight box 61. The control system then drives the fifth electric telescopic cylinder 646 to reverse its action, simultaneously sealing the top flow port 611 and the bottom flow port 612, increasing the device's weight and making the device stable on the seabed.

[0127] S4, Surface Sampling

[0128] The first electric telescopic cylinder 21 drives the central telescopic cylinder 22 to extend, so that the central telescopic cylinder 22 is inserted into the seabed surface sediments. The third electric telescopic cylinder 231 drives the first piston 232 to slide along the inner wall of the central telescopic cylinder 22 and draw surface sediment samples through the first sampling port 221.

[0129] S5, Mid-layer Sampling

[0130] The second electric telescopic cylinder 31 of the middle layer sampling mechanism 3 drives the corresponding edge telescopic cylinder 32 to extend, so that the edge telescopic cylinder 32 is inserted into the middle layer sediment of the seabed. The corresponding fourth electric telescopic cylinder 331 drives the second piston 332 to slide along the inner wall of the edge telescopic cylinder 32, and draws the middle layer sediment sample through the corresponding second sampling port 321.

[0131] S6, Deep Sampling

[0132] The second electric telescopic cylinder 31 of the deep sampling mechanism 4 drives the corresponding edge telescopic cylinder 32 to extend, so that the edge telescopic cylinder 32 is inserted into the deep seabed sediments. The corresponding fourth electric telescopic cylinder 331 drives the second piston 332 to slide along the inner wall of the edge telescopic cylinder 32, and draws deep sediment samples through the corresponding second sampling port 321.

[0133] S7, Sample Recovery

[0134] Each sampling unit retracts sequentially into the multi-point sampling tube 1, and the seabed microplastic sampling device is retrieved to the mother ship. Surface sediment samples, mid-layer sediment samples, and deep sediment samples are then taken out and preserved.

[0135] This device is an unmanned operating equipment specifically designed for seabed microplastic sampling. Its core design concept is to achieve high-fidelity, high-reliability, and high-data-comparability seabed sediment sample acquisition through multi-point synchronous sampling, multi-level vertical profile acquisition, mirror control experimental design, and active impact buffering and adaptive attitude adjustment.

[0136] The device has a mirror-symmetrical layout, with the central connecting frame 5 as the center of symmetry, and multi-point sampling tubes 1 set on both sides. Each multi-point sampling tube 1 integrates a three-layer sampling mechanism, which can obtain sediment samples from the surface, middle and deep layers in a single deployment. Simultaneous sampling on both sides can serve as a control for each other.

[0137] The detailed working process of this device is as follows:

[0138] S1: Device lowering and attitude monitoring

[0139] The seabed microplastic sampling device was lowered from the mother ship to the target area. After entering the water, the device slowly sank under its own weight.

[0140] During this process, sensor group 7 works continuously: depth sensor 71 detects the water depth of the device in real time, attitude sensor 72 detects the tilt angle of the device in real time, and altimeter 73 detects the height of the device from the seabed in real time. This device can also integrate other sensors in this technical field for monitoring or to realize other auxiliary functions. All status information collected by the sensors is transmitted to the control system in real time.

[0141] At this time, the electromagnet 533 of the flow guiding and deceleration mechanism 53 is energized, and the magnetic suction plate 534 is attracted to the lower end of the horizontal connecting beam 512, which blocks the swirl vane plate 531 and the flow stabilizing hole 532. The deceleration effect of the flow guiding and deceleration mechanism 53 has not yet been exerted, and the device sinks at a relatively fast speed.

[0142] S2: Bottom-out cushioning

[0143] When the altimeter 73 detects that the device is approaching the seabed to the preset trigger depth, the control system issues a command, the electromagnet 533 is de-energized and demagnetized, and the magnetic plate 534 detaches from the lower end of the horizontal connecting beam 512 under its own weight and the action of water flow, exposing the vortex blade 531 and the flow stabilizing hole 532. The connecting rope 535 connects the detached magnetic plate 534 to the side wall of the horizontal connecting beam 512.

[0144] The flow-guiding and deceleration mechanism 53 begins to function as a deceleration device: the swirl vane 531 forces the surrounding water flow to change direction, increasing water flow resistance, consuming the kinetic energy of the device's descent, and reducing the device's descent speed; the flow-stabilizing orifice 532 balances the water pressure difference on both sides of the swirl vane 531, making the device's descent process more stable. The flow-stabilizing orifice 532 preferably adopts a cylindrical straight hole design. The straight hole processing technology is mature, and it can be formed in one step using a standard drill bit, which is low in cost and high in efficiency. At the same time, the flow resistance characteristics of the straight hole are stable, making it easy to accurately control the device's descent speed by adjusting parameters such as the orifice diameter and number.

[0145] The device continues to descend until it touches the bottom. Upon contact, the bottom buffer 522 first contacts the seabed. The first rubber pad 5221, located directly below the I-beam connecting beam 51, primarily bears the impact force in the central area. The second rubber pads 5222 are positioned below the multi-point sampling tubes 1, bearing the impact force in the sampling tube areas on both sides. The bottom buffer 522 absorbs the impact energy through the elastic deformation of the rubber material, providing initial cushioning and support for the device.

[0146] Upon contact with the seabed, the bottom buffer 522, through the elastic deformation of its rubber material, converts the kinetic energy of the device's descent into elastic potential energy, effectively absorbing the impact energy and providing initial cushioning and support. This buffering mechanism not only protects the structural safety of the device itself, but more importantly, it prevents the main body of the device from directly colliding rigidly with the seabed, thus preventing violent disturbance and impact damage to the surface sediments and protecting the in-situ state of the microplastic-rich surface sediment layer. This provides a favorable prerequisite for the subsequent accurate sampling by the surface sampling mechanism 2, the middle sampling mechanism 3, and the deep sampling mechanism 4, ensuring the representativeness of the samples and the reliability of the data.

[0147] S3: Adaptive weight loading and attitude stabilization

[0148] When the device is not deployed, the interior of the adaptive counterweight box 61 is a closed hollow cavity filled with air. During the entire descent of the device, the air inside the adaptive counterweight box 61 is sealed inside the cavity, forming a buffer layer similar to an "air cushion," which further reduces the impact and disturbance of the device on the seabed microplastic layer, forming a double buffer protection with the elastic buffer of the bottom buffer component 522.

[0149] After the device touches the bottom and is initially cushioned and supported by the bottom buffer 522, the attitude sensor 72 transmits the device's tilt angle information to the control system in real time. Once the control system determines that the device has landed stably, it issues a command to initiate the adaptive counterweight loading process.

[0150] Phase 1 – Top Circulation Port 611 Opened First:

[0151] The control system drives the fifth electric telescopic cylinder 646 to move, and the fifth electric telescopic cylinder 646 drives the vertical moving part 643 to move as a whole through the moving plate 647 and the diverging rod 648.

[0152] Due to the action of the delayed release mechanism 65, the top conical piston head 645 first separates from the top flow port 611, opening the top flow port 611; at the same time, the bottom conical piston head 645 remains sealed to the bottom flow port 612 under the action of the extension spring 653 of the delayed release mechanism 65, and the bottom flow port 612 has not yet been opened.

[0153] At this time, seawater enters the adaptive counterweight box 61 only through the top flow port 611. Air inside the adaptive counterweight box 61 is discharged outwards through the top flow port 611 as the seawater enters. Since the bottom flow port 612 is closed, seawater enters only from the top, preventing the generation of eddies or jets at the bottom of the device, thus avoiding erosion and disturbance to the microplastic layer on the seabed surface.

[0154] Phase Two – Delayed Opening of Bottom Circulation Port 612:

[0155] When the seawater in the adaptive counterweight box 61 is injected to the preset amount, the delay action of the delayed release mechanism 65 is completed, the compression of the telescopic spring 653 reaches the threshold, and the bottom conical piston head 645 is further driven by the fifth electric telescopic cylinder 646 to separate from the bottom flow port 612, and the bottom flow port 612 is opened.

[0156] At this point, the air inside the adaptive counterweight box 61 has been largely expelled, and the water pressure inside and outside the box is approaching equilibrium. Opening the bottom flow port 612 will not generate violent jets or eddies. Seawater enters the adaptive counterweight box 61 smoothly through both the top flow port 611 and the bottom flow port 612, completing the final water filling.

[0157] Phase Three – Enclosure and Counterweight Locking:

[0158] Once the adaptive counterweight box 61 is filled with seawater to the preset level, the control system drives the fifth electric telescopic cylinder 646 to reverse its direction. This, via the vertical moving part 643, causes the conical piston head 645 to simultaneously seal and close the top flow port 611 and the bottom flow port 612. At this point, the adaptive counterweight box 61 is filled with seawater, and the overall weight of the device increases significantly.

[0159] The added counterweight makes the device more stable on the seabed, providing sufficient downforce and stability for the subsequent insertion and suction sampling operations of the surface sampling mechanism 2, the middle sampling mechanism 3 and the deep sampling mechanism 4, ensuring that each telescopic cylinder can be smoothly inserted into the sediment and complete accurate sampling.

[0160] S4: Surface sampling

[0161] Once the device is stable, stratified sampling begins.

[0162] The control system issues a command, the first electric telescopic cylinder 21 extends, and drives the central telescopic cylinder 22 to extend the multi-point sampling cylinder 1 axially downward, so that the end of the central telescopic cylinder 22, that is, the end with the first sampling port 221, is inserted into the seabed surface sediment.

[0163] Subsequently, the third electric telescopic cylinder 231 retracts, causing the first piston 232 to slide upwards along the inner wall of the central telescopic cylinder 22. The side wall of the first piston 232 slides and seals against the inner wall of the central telescopic cylinder 22, creating a negative pressure inside the central telescopic cylinder 22. Under the action of negative pressure, the surface sediment sample is drawn into the central telescopic cylinder 22 through the first sampling port 221.

[0164] Once the preset amount is drawn in, the third electric telescopic cylinder 231 stops operating. The first electric telescopic cylinder 21 retracts, pulling the central telescopic cylinder 22 back into the multi-point sampling cylinder 1.

[0165] At the same time, the multi-point sampling tube 1 on the other side simultaneously performs the exact same surface sampling action to obtain a second set of surface sediment samples.

[0166] S5: Mid-layer sampling

[0167] The control system issues a command, and the second electric telescopic cylinders 31 of each mid-layer sampling mechanism 3 extend synchronously, driving the corresponding edge telescopic cylinders 32 to extend the multi-point sampling cylinder 1 axially downwards, so that the end of each edge telescopic cylinder 32, that is, the end with the second sampling port 321, is inserted into the mid-layer sediment of the seabed. The pointed conical end design of the edge telescopic cylinder 32 facilitates smooth insertion into the sediment.

[0168] Subsequently, the fourth electric telescopic cylinders 331 of each intermediate layer sampling mechanism 3 retract synchronously, driving the corresponding second pistons 332 to slide upward along the inner wall of the edge telescopic cylinder 32. The side wall of the second piston 332 slides and seals with the inner wall of the edge telescopic cylinder 32, creating a negative pressure inside the edge telescopic cylinder 32. Under the action of negative pressure, the intermediate layer sediment sample is drawn into the edge telescopic cylinder 32 through the corresponding second sampling port 321.

[0169] Once the preset amount is drawn in, the fourth electric telescopic cylinder 331 stops operating, and the second electric telescopic cylinder 31 retracts, retracting the corresponding edge telescopic cylinder 32 back into the multi-point sampling cylinder 1.

[0170] At the same time, the middle sampling mechanism 3 of the multi-point sampling tube 1 on the other side performs the exact same middle sampling action.

[0171] S6: Deep Sampling

[0172] The second electric telescopic cylinder 31 of each deep sampling mechanism 4 extends synchronously, driving the corresponding edge telescopic cylinder 32 to extend the multi-point sampling cylinder 1 axially downward, so that the end of each edge telescopic cylinder 32, that is, the end with the second sampling port 321, is inserted into the deep seabed sediment.

[0173] Subsequently, the fourth electric telescopic cylinders 331 of each deep sampling mechanism 4 retract synchronously, driving the corresponding second pistons 332 to slide upward along the inner wall of the edge telescopic cylinder 32, creating a negative pressure inside the edge telescopic cylinder 32. Under the action of negative pressure, the deep sediment samples are drawn into the edge telescopic cylinder 32 through the corresponding second sampling port 321.

[0174] Once the preset amount is drawn in, the fourth electric telescopic cylinder 331 stops operating, and the second electric telescopic cylinder 31 retracts, retracting the corresponding edge telescopic cylinder 32 back into the multi-point sampling cylinder 1.

[0175] At the same time, the deep sampling mechanism 4 of the multi-point sampling tube 1 on the other side performs the exact same deep sampling action.

[0176] S7: Sample Recovery

[0177] After the surface sampling mechanism 2, the middle sampling mechanism 3, and the deep sampling mechanism 4 are completely retracted into the multi-point sampling tube 1, the mother ship will retrieve the seabed microplastic sampling device to the deck.

[0178] During the recovery process, the connecting rope 535 will bring back the previously detached magnetic plate 534, preventing the magnetic plate 534 from being left on the seabed and causing secondary pollution.

[0179] After the device is recovered to the mother ship, sediment samples from each layer are retrieved from the central telescopic cylinder 22 and each edge telescopic cylinder 32. Each multi-point sampling cylinder 1 can obtain three sets of samples from the surface, middle, and deep layers. The two multi-point sampling cylinders 1 on both sides obtain a total of six sets of samples, with at least two sets each from the surface, middle, and deep layers, serving as controls. All samples are sealed and preserved, with information such as sampling point, layer, and time marked for subsequent laboratory analysis.

[0180] It should be noted that a camera and other existing sensor components can be integrated into the bottom of this device to further expand its functionality and provide visualization and multi-parameter environmental monitoring support for the sampling process. During sampling, the central and peripheral telescopic cylinders primarily use negative pressure suction to draw sediment samples into the cylinders, preserving the main sediment within each cylinder. Even if some sediment is lost during retrieval, it does not affect the integrity and representativeness of the main sample. To further improve sample preservation integrity, push-type switch covers can be installed at each sampling port to seal the port after sampling, achieving airtight sample preservation. Furthermore, particle filters can be integrated into each sampling port to filter larger particles, preventing interference with subsequent microplastic analysis. The aforementioned camera, push-type switch covers, and particle filters are common technical means in this field, and those skilled in the art can select and configure them according to actual needs; further details are omitted here.

[0181] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0182] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A seabed microplastic sampling device, characterized in that, include: Multi-point sampling tubes (1) are arranged in a mirror symmetrical manner on both sides of the central connecting frame (5). Each multi-point sampling tube (1) is arranged in sequence along the axial direction with a surface sampling mechanism (2), a middle sampling mechanism (3) and a deep sampling mechanism (4). The surface sampling mechanism (2), the middle sampling mechanism (3) and the deep sampling mechanism (4) are used to collect seabed surface sediment, middle sediment and deep sediment samples respectively. The multi-point sampling tubes (1) on both sides are arranged in a mirror symmetrical manner to collect two sets of samples at the same sampling point for mutual control. The central connecting frame (5) is fixedly connected between the two multi-point sampling tubes (1) to keep the relative distance between the two multi-point sampling tubes (1) fixed. The central connecting frame (5) is also provided with a flow guiding and deceleration mechanism (53) to slow down the sinking speed during the sinking process of the device. An adaptive counterweight mechanism (6) is movably mounted on the central connecting frame (5). The adaptive counterweight mechanism (6) responds to the status information of the device and dynamically adjusts the overall counterweight of the device. The sensor group (7) is set on the central connecting frame (5) or the multi-point sampling tube (1). The sensor group (7) includes a depth sensor (71), an attitude sensor (72) and an altimeter (73). The depth sensor (71) is used to detect the water depth where the device is located. The attitude sensor (72) is used to detect the tilt angle of the device. The altimeter (73) is used to detect the height of the device from the seabed.

2. The seabed microplastic sampling device according to claim 1, characterized in that, The multi-point sampling cylinder (1) has a hollow cylindrical structure. The surface sampling mechanism (2) is located in the center of the multi-point sampling cylinder (1) and is driven to extend and retract by the first electric telescopic cylinder (21). The middle sampling mechanism (3) and the deep sampling mechanism (4) are evenly distributed around the surface sampling mechanism (2) in the circumferential direction. The middle sampling mechanism (3) and the deep sampling mechanism (4) are alternately arranged in the circumferential direction. The middle sampling mechanism (3) and the deep sampling mechanism (4) are driven to extend and retract by the second electric telescopic cylinder (31) respectively.

3. The seabed microplastic sampling device according to claim 2, characterized in that, The surface sampling mechanism (2) includes: The first electric telescopic cylinder (21) is fixedly installed in the center of the multi-point sampling tube (1); The central telescopic cylinder (22) has a hollow cylindrical structure. The central telescopic cylinder (22) is installed through the center of the multi-point sampling cylinder (1). One end of the central telescopic cylinder (22) is fixedly installed on the telescopic end of the first electric telescopic cylinder (21). The other end of the central telescopic cylinder (22) is circumferentially provided with multiple first sampling ports (221). The first suction assembly (23) is disposed inside the central telescopic cylinder (22). The first suction assembly (23) consists of a third electric telescopic cylinder (231) and a first piston (232). The third electric telescopic cylinder (231) is fixedly installed inside the central telescopic cylinder (22). The first piston (232) is fixedly installed at the telescopic end of the third electric telescopic cylinder (231), and the side wall of the first piston (232) slides and seals with the inner wall of the central telescopic cylinder (22).

4. The seabed microplastic sampling device according to claim 3, characterized in that, The middle-layer sampling mechanism (3) and the deep-layer sampling mechanism (4) have the same structure, both including: The second electric telescopic cylinder (31) is fixedly installed at the inner edge of the multi-point sampling tube (1); The edge telescopic cylinder (32) has a hollow cylindrical structure. One end of the edge telescopic cylinder (32) is cone-shaped. The edge telescopic cylinder (32) is disposed through the edge of the multi-point sampling cylinder (1). One end of the edge telescopic cylinder (32) is fixedly installed on the telescopic end of the second electric telescopic cylinder (31). The other end of the edge telescopic cylinder (32) has multiple second sampling ports (321) circumferentially opened on the side wall. The second suction assembly (33) is disposed inside the edge telescopic cylinder (32). The second suction assembly (33) consists of a fourth electric telescopic cylinder (331) and a second piston (332). The fourth electric telescopic cylinder (331) is fixedly installed inside the edge telescopic cylinder (32), and the second piston (332) is fixedly installed at the telescopic end of the fourth electric telescopic cylinder (331). The side wall of the second piston (332) is slidably sealed with the inner wall of the edge telescopic cylinder (32).

5. The seabed microplastic sampling device according to claim 4, characterized in that, The central connecting frame (5) includes: An I-beam connecting beam (51) is horizontally positioned between two multi-point sampling tubes (1). The I-beam connecting beam (51) consists of a central crossbeam (511) and horizontal connecting beams (512) located at both ends of the central crossbeam (511). The ends of the horizontal connecting beams (512) are fixedly installed on the side walls of the corresponding multi-point sampling tubes (1). The bottom support (52) is fixedly installed below the I-beam connecting beam (51). The bottom support (52) consists of a vertical support rod (521) and a bottom buffer (522). The bottom buffer (522) is located directly below the I-beam connecting beam (51). The vertical support rod (521) is mirror-symmetrically arranged between the central crossbeam (511) and the bottom buffer (522). The bottom buffer (522) consists of a first rubber pad (5221) with a straight groove and a second rubber pad (5222) symmetrically arranged on the side wall of the first rubber pad (5221). The first rubber pad (5221) is located directly below the I-beam connecting beam (51), and the second rubber pad (5222) is respectively arranged below the multi-point sampling tube (1).

6. The seabed microplastic sampling device according to claim 5, characterized in that, The flow guiding and deceleration mechanism (53) includes: Swirl blades (531) are arranged in a linear array on the surface of the horizontal connecting beam (512) along the length direction of the horizontal connecting beam (512); A flow stabilizing hole (532) is provided through the horizontal connecting beam (512), and each flow stabilizing hole (532) is respectively provided between two adjacent swirl blades (531); Electromagnets (533) are evenly distributed at the lower end of the horizontal connecting beam (512); A magnetic suction plate (534) is attached to the lower end of the horizontal connecting beam (512) to shield the swirl vane (531) and the flow stabilizing hole (532). A connecting rope (535) is provided on the side wall of the horizontal connecting beam (512). One end of the connecting rope (535) is fixedly connected to the horizontal connecting beam (512), and the other end of the connecting rope (535) is fixedly connected to the magnetic plate (534) for recycling after the magnetic plate (534) is detached.

7. The seabed microplastic sampling device according to claim 6, characterized in that, The adaptive counterweight mechanism (6) includes: The adaptive counterweight box (61) has a hollow cavity inside. The adaptive counterweight box (61) is symmetrically fixed with lifting sliding blocks (62). The lifting sliding blocks (62) are slidably installed on the corresponding vertical support rod (521). The adaptive counterweight box (61) has a top flow port (611) and a bottom flow port (612) at the top center and bottom center, respectively. Displacement limiting blocks (63) are fixedly installed on the top and bottom of each of the vertical support rods (521) to limit the sliding stroke of the adaptive counterweight box (61) along the vertical support rod (521); The central switching mechanism (64) is located in the center of the adaptive counterweight box (61) and is used to control the opening and closing of the top flow port (611) and the bottom flow port (612).

8. The seabed microplastic sampling device according to claim 7, characterized in that, The central switching mechanism (64) includes: A hollow waterproof cylinder (641) is located in the center of the adaptive counterweight box (61). Side wing fixing rods (642) are fixedly installed on both sides of the hollow waterproof cylinder (641), and the ends of the side wing fixing rods (642) are fixedly installed on the inner wall of the adaptive counterweight box (61). The vertical moving part (643) is disposed inside the hollow waterproof cylinder (641). The vertical moving part (643) consists of a plurality of circumferentially distributed vertical moving rods (6431) and circular plates (6432) respectively fixedly installed at the ends of each vertical moving rod (6431). A piston rod (644) is fixedly mounted at one end on the corresponding circular plate (6432). A conical piston head (645) is fixedly mounted at the end of the piston rod (644). The top flow port (611) and the bottom flow port (612) are both inverted conical orifices adapted to the conical piston head (645). The conical piston head (645) is movably disposed above the corresponding top flow port (611) and the bottom flow port (612) for sealing or opening the corresponding flow ports. The fifth electric telescopic cylinder (646) is fixedly installed inside the hollow waterproof cylinder (641). A movable plate (647) is fixedly installed at the output end of the fifth electric telescopic cylinder (646). The side wall of the movable plate (647) is fixedly connected to each of the vertical movable rods (6431) through a diverging rod (648).

9. The seabed microplastic sampling device according to claim 8, characterized in that, A delayed release mechanism (65) is further provided between the circular plate (6432) at the bottom and the corresponding piston rod (644), the delayed release mechanism (65) comprising: The delayed release cylinder (651) is fixedly installed on the circular plate (6432) located at the bottom. The interior of the delayed release cylinder (651) is hollow, and one end of the piston rod (644) located at the bottom extends into the interior of the delayed release cylinder (651). A limiting plate (652) is fixedly installed at the end of the piston rod (644), and the limiting plate (652) is slidably disposed inside the delayed release cylinder (651); A telescopic spring (653) is disposed inside the delayed release cylinder (651). One end of the telescopic spring (653) abuts against the limiting plate (652), and the other end of the telescopic spring (653) abuts against the inner wall of the delayed release cylinder (651).

10. The sampling method of the seabed microplastic sampling device according to claim 9, characterized in that, Includes the following steps: S1. Device lowering and attitude monitoring The seabed microplastic sampling device is hoisted from the mother ship to the target sea area. The sensor group (7) monitors the sinking depth, tilt angle and height from the seabed of the device in real time and transmits the collected status information to the control system. S2, Bottom Contact Buffer When the altimeter (73) detects that the device is approaching the seabed, the flow guiding and deceleration mechanism (53) guides and decelerates the surrounding water flow to reduce the sinking speed of the device; after the device touches the bottom, the bottom buffer (522) provides initial buffer support for the device. S3, Adaptive Weight Loading and Attitude Stabilization After the device touches the bottom, the control system drives the fifth electric telescopic cylinder (646) to operate. Under the action of the delayed release mechanism (65), the top flow port (611) opens first, and seawater enters the adaptive counterweight box (61) from the top. The bottom flow port (612) remains closed to avoid generating eddy currents at the bottom that disturb the microplastic layer. After the delay is completed, the bottom flow port (612) opens, and seawater smoothly fills the adaptive counterweight box (61). The control system drives the fifth electric telescopic cylinder (646) to operate in the opposite direction, sealing the top flow port (611) and the bottom flow port (612) at the same time, increasing the weight of the device and making the device sit stably on the seabed. S4, Surface Sampling The first electric telescopic cylinder (21) drives the central telescopic cylinder (22) to extend, so that the central telescopic cylinder (22) is inserted into the seabed surface sediment. The third electric telescopic cylinder (231) drives the first piston (232) to slide along the inner wall of the central telescopic cylinder (22) and draw surface sediment samples through the first sampling port (221). S5, Mid-layer Sampling The second electric telescopic cylinder (31) of the middle layer sampling mechanism (3) drives the corresponding edge telescopic cylinder (32) to extend, so that the edge telescopic cylinder (32) is inserted into the middle layer sediment of the seabed, and the corresponding fourth electric telescopic cylinder (331) drives the second piston (332) to slide along the inner wall of the edge telescopic cylinder (32) and draw the middle layer sediment sample through the corresponding second sampling port (321); S6, Deep Sampling The second electric telescopic cylinder (31) of the deep sampling mechanism (4) drives the corresponding edge telescopic cylinder (32) to extend, so that the edge telescopic cylinder (32) is inserted into the deep seabed sediments. The corresponding fourth electric telescopic cylinder (331) drives the second piston (332) to slide along the inner wall of the edge telescopic cylinder (32) and draw deep sediment samples through the corresponding second sampling port (321). S7, Sample Recovery Each sampling unit retracts into the multi-point sampling tube (1) in sequence, and the seabed microplastic sampling device is retrieved to the mother ship. Surface sediment samples, middle sediment samples and deep sediment samples are taken out and preserved.

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