Passive groundwater stratification sampling device driven by pressure difference, sampling system and method

Abstract

The pressure difference-driven passive groundwater stratified sampling device, sampling system and method of the present invention belong to the field of site pollution investigation and risk assessment. A stratified barrier is set between the samplers, and a water hole and a breathing valve matched with the water hole are provided on the stratified barrier. In the process of vertically lowering the sampler and the stratified barrier into the well pipe device, the breathing valve can be opened under the action of hydraulic force to ensure that the sampler and the stratified barrier can be smoothly installed to the designated position in the monitoring well. After the installation is completed, the breathing valve is closed under the action of gravity, and the water hole is effectively blocked, which can effectively block the upper and lower connection of the groundwater in the monitoring well during the sampling process, ensuring the realization of accurate fixed-depth stratified sampling. The entire sampling process does not cause disturbance to the groundwater in the monitoring well, and the sample detection results can better characterize the pollution status of the site groundwater under natural conditions. The sampling device and the sampling system have low development costs and simple operation, which can make up for the defects of current sampling technology and devices.

Description

Technical Field

[0001] The present invention belongs to the field of site pollution investigation and risk assessment, and specifically relates to a pressure difference driven passive groundwater stratification sampling device, a sampling system and a method. Background Art

[0002] Historically, many chemical and coking enterprises in my country that are involved in the production, processing, transportation and storage of organic chemical products may cause soil and groundwater pollution in local areas of the factory due to leakage in the transmission pipelines and storage tanks. Now many similar polluting enterprises in my country are gradually shut down and relocated, and the land in the factory area has gradually changed from the original industrial land to residential, commercial and public facilities land to meet the demand for construction land in the process of urbanization. In order to ensure the environmental safety of such plots in the future when they are redeveloped as residential and other construction land, the state explicitly requires that before the land of such enterprises is redeveloped as residential and other construction land, it is necessary to sample the soil and groundwater on the site, identify the spatial distribution of pollution, and conduct risk assessment in combination with specific land use planning.

[0003] At present, the investigation of groundwater pollution is mainly carried out by building groundwater monitoring wells, collecting groundwater samples and sending them to the laboratory for pollutant testing to determine the degree of pollution. Traditional groundwater sampling usually requires the use of a submersible pump or an extraction pump to pump groundwater to the ground and then transfer it to a dedicated groundwater sampling bottle. This type of sampling technology will cause a certain degree of disturbance to the groundwater samples during the sampling process. For volatile pollutants, the disturbance during the sampling process usually leads to a low concentration of pollutants detected.

[0004] To overcome this defect, technicians have developed low-flow sampling technology and supporting equipment, such as low-flow well-washing sampling technology represented by airbag pumps, submersible pumps and peristaltic pumps. However, due to the limitations of the lift or suction range of the sampling equipment, these technologies cannot collect representative samples in sites with deep groundwater. For sites with thicker water layers (greater than 3 m), in order to find out the vertical distribution of pollutants in the aquifer, when using traditional or low-flow well-washing sampling technology to collect groundwater samples, it is necessary to set up a group of wells at the same sampling point, resulting in increased drilling and well construction costs. At the same time, in order to avoid cross-contamination, after completing the sample collection of a monitoring well using this technology, the sampling pump and pipeline need to be cleaned on-site, resulting in low on-site sampling efficiency.

[0005] In addition, the passive sampling bag sampling technology based on the principle of gradient diffusion of pollutant concentration is suitable for the collection of undisturbed groundwater samples at any groundwater depth. However, this technology is currently mainly suitable for the collection of groundwater samples contaminated by some volatile organic compounds. Moreover, in the same groundwater monitoring well, due to the lack of supporting devices to block the mixing of groundwater at different depths in the well pipe, this technology is also difficult to achieve stratified sampling in the same groundwater monitoring well. Summary of the invention

[0006] The purpose of the present invention is to provide a pressure difference driven passive groundwater stratified sampling device, sampling system and method to solve the technical problems that low-flow sampling technology needs to set up a group of wells when collecting samples in a site with a water layer thickness greater than 3m, resulting in high drilling and well construction costs and low sampling efficiency; passive sampling bag sampling technology is only suitable for the collection of some volatile organic compound contaminated groundwater samples, and it is difficult to achieve stratified sampling in the same groundwater monitoring well.

[0007] In order to solve the above technical problems, the present invention provides a pressure difference driven passive groundwater stratification sampling device, comprising:

[0008] The samplers are arranged vertically and spaced apart, the samplers are hollow structures and have pores on their side walls for pollutants to penetrate into the samplers, and the bottom of the samplers is provided with a sampling port;

[0009] A layered barrier is connected between adjacent samplers, the layered barrier comprises a barrier diaphragm, a water hole extending vertically therethrough is provided on the barrier diaphragm, and a breathing valve cooperating with the water hole is connected to the barrier diaphragm above the water hole;

[0010] The air guide pipe is connected to all the samplers and the layered barrier in sequence, and the air guide pipe is provided with a one-way valve for controlling the flow direction from bottom to top.

[0011] Preferably, the sampler includes a cylindrical sampler body and sealing covers connected to the top and bottom of the sampler body. The sampler body is made of micron-grade porous rigid polyethylene, a sampling port is provided on the bottom sealing cover, and the top and bottom sealing covers are correspondingly provided with first air duct interfaces that cooperate with the air duct.

[0012] Preferably, an exhaust port is also provided on the sealing cover at the top, and the exhaust port, the air duct and the first air duct interface at the top are connected via a three-way joint.

[0013] Preferably, a second air duct interface cooperating with the air duct is provided on the barrier membrane.

[0014] Preferably, the sampler and the layered barrier are connected by a fixed rope.

[0015] Preferably, a lead sinker is connected to the bottom end of the bottommost sampler.

[0016] In addition, the present invention also provides a pressure differential driven passive groundwater stratified sampling system, comprising the pressure differential driven passive groundwater stratified sampling device as described above, and further comprising:

[0017] A well pipe device is vertically arranged along the center of the wellbore, including a solid pipe and a screen pipe connected vertically at intervals, and the topmost part is the solid pipe, the top and bottom of the well pipe device are respectively connected to a well cover and a pipe plug, the well cover is provided with a seal, the pressure difference driven passive groundwater stratification sampling device is arranged in the well pipe device, and the topmost sampler is connected to the well cover by a fixed rope, and the sampler and the stratification barrier are respectively arranged in the screen pipe and the solid pipe;

[0018] The filter material and barrier device are arranged between the outer wall of the well pipe device and the wellbore wall, and include filter material and barrier layers. The filter material and barrier layers are arranged at intervals from bottom to top and the topmost layer is the barrier layer. The filter material is arranged between the outer wall of the screen tube and the wellbore wall. The top and bottom of the filter material both extend beyond the screen tube. The filter material and barrier device also include a sealing layer, which is arranged between the outer wall of the well pipe device and the wellbore wall at the top of the topmost barrier layer.

[0019] Preferably, the filter material is quartz sand, the barrier layer is bentonite slurry, and the sealing layer is cement slurry.

[0020] Preferably, the top and bottom of the filter material both extend beyond the screen tube by at least 0.3 m.

[0021] In addition, the present invention also provides a method for sampling using the passive groundwater stratification sampling system driven by the pressure difference as described above, comprising the following steps:

[0022] Step 1: determine the groundwater sampling and testing points and drill wells;

[0023] Step 2: vertically install the well pipe device in the wellbore, ensuring that the well pipe device is located in the center of the wellbore;

[0024] Step 3: Fill filter material and barrier device between the outer wall of the well pipe device and the wellbore wall, fill filter material and barrier layer from bottom to top, and the top is the barrier layer, to ensure that the filter material is filled between the outer wall of the screen tube and the wellbore wall;

[0025] Step 4: When the top barrier layer is 0.3-0.5m above the ground, stop loading the barrier layer, and then pour the sealing layer between the outer wall of the well pipe device and the wellbore wall at the top of the barrier layer until the sealing layer is 0.2-0.3m above the ground;

[0026] Step 5: According to the designed sampling depth, connect the sampler and the layered barrier from top to bottom, and close all sampling ports;

[0027] Step 6: After the layered barrier and the one-way valve are connected through the air guide tube, the air guide tube is connected to the sampler from top to bottom, and the top of the air guide tube is connected to the manhole cover;

[0028] Step 7: Place the pressure-differential-driven passive groundwater stratification sampling device connected to the well cover vertically into the well pipe device, fix the well cover to the solid pipe at the top of the well pipe device, open the seal on the well cover, and record the installation completion time;

[0029] Step 8: 15 days after installation, close the seal on the manhole cover, open the manhole cover, and lift the sampler and layer barrier to the ground;

[0030] Step 9. Open the sampling port at the bottom of the sampler and transfer the sample to a special sample bottle. The sampling is completed.

[0031] Compared with the prior art, the present invention has the following characteristics and beneficial effects:

[0032] (1) The present invention sets a layered barrier between the samplers. Since the layered barrier is provided with a water hole and a breathing valve cooperating with the water hole, when the sampler and the layered barrier are vertically lowered into the well pipe device, the breathing valve can be opened under the action of hydraulic pressure, ensuring that the sampler and the layered barrier can be smoothly installed at the designated position in the monitoring well. After the installation is completed, the breathing valve is closed under the action of gravity, and the water hole is effectively blocked, which can effectively block the upper and lower connection of groundwater in the monitoring well during the sampling process, ensuring the realization of accurate fixed-depth layered sampling.

[0033] (2) The present invention can utilize the water pressure of groundwater in the well pipe device under natural flow field conditions to press the groundwater sample at the sampling position into the sampler through the micropores on the side wall of the sampler. The entire sampling process does not cause disturbance to the groundwater in the monitoring well. The sample detection results can better characterize the pollution status of the groundwater on the site under natural conditions, avoiding the defect of too low concentration of pollutants detected in the sample due to disturbance in the traditional sampling process. Since the groundwater sample is pressed into the passive sampler by water pressure, there is no need to rely on the suction effect of the pump like the traditional groundwater sampling technology, avoiding the defect of dust raised by the pump or too low suction range under special hydrogeological conditions and the inability to collect groundwater samples.

[0034] (3) The pressure difference driven passive groundwater stratified sampling device and sampling system of the present invention have low development cost and simple operation, and can make up for the defects of current sampling technology and devices. It is of great significance to improve the current groundwater sampling technology system and support groundwater pollution investigation in contaminated sites in my country. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 Schematic diagram of the elevation structure of a passive groundwater stratification sampling device driven by pressure difference.

[0036] Figure 2 This is a schematic diagram of the main structure of the sampler.

[0037] Figure 3Schematic diagram of the sampler's top view.

[0038] Figure 4 This is a schematic diagram of the main structure of the layered barrier.

[0039] Figure 5 Schematic diagram of the top view of the layered barrier.

[0040] Figure 6 This is a schematic diagram of the main structure of the passive groundwater stratified sampling system driven by pressure difference.

[0041] Figure 7 Schematic diagram of the top view of the passive groundwater stratified sampling system driven by pressure difference.

[0042] Figure 8 It is a schematic diagram of the main structure of the manhole cover.

[0043] Fig. 9 This is a schematic diagram of the structure of a manhole cover from a top view.

[0044] The accompanying drawings are marked with: 1-sampler, 11-sampling port, 12-sampler body, 13-sealing cover, 14-first air duct interface, 15-exhaust port, 2-layered barrier, 21-barrier diaphragm, 22-water hole, 23-breathing valve, 24-second air duct interface, 3-air duct, 4-fixing rope, 5-check valve, 6-lead sinker, 7-well pipe device, 71-real pipe, 72-screen pipe, 73-pipe plug, 74-well cover, 75-seal, 8-filter material and barrier device, 81-filter material, 82-barrier layer, 83-cement slurry. DETAILED DESCRIPTION

[0045] In order to make the technical means, innovative features, objectives and effects achieved by the present invention easy to understand, the present invention is further described below.

[0046] The embodiments described herein are specific embodiments of the present invention, which are used to illustrate the concept of the present invention, are illustrative and exemplary, and should not be construed as limiting the embodiments of the present invention and the scope of the present invention. In addition to the embodiments described herein, those skilled in the art can also adopt other obvious technical solutions based on the claims and the contents disclosed in the specification of this application, including technical solutions that adopt any obvious replacement and modification of the embodiments described herein.

[0047] In the description of the present invention, it should be noted that the terms "upper", "lower", "inner", "outer", "front end", "rear end", "two ends", "one end", "the other end" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0048] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "provided with", "connected", etc. should be understood in a broad sense. For example, "connected" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0049] like Figure 1 As shown, a pressure difference driven passive groundwater stratified sampling device comprises a sampler 1, a stratified barrier 2 and an air guide tube 3.

[0050] The samplers 1 are arranged at intervals along the vertical direction. The sampler 1 is a hollow structure and has pores on its side walls for pollutants to penetrate into the sampler 1. A sampling port 11 is provided at the bottom of the sampler 1. The layered barrier 2 is connected between adjacent samplers 1. The layered barrier 2 and the sampler 1 are preferably connected by a fixing rope 4. The layered barrier 2 includes a barrier diaphragm 21, and a water hole 22 that passes through the barrier diaphragm 21 is provided. A breathing valve 23 that cooperates with the water hole 22 is connected to the barrier diaphragm 21 above the water hole 22. The air duct 3 connects all the samplers 1 and the layered barrier 2 in sequence, and a one-way valve 5 that controls the flow direction from bottom to top is provided on the air duct 3. The bottom end of the air duct 3 is connected to the exhaust port 15 on the sealing cover 13 at the top of the bottom sampler 1 and the first air duct interface 14 through a three-way pipe.

[0051] like Figure 2 and 3As shown, the sampler 1 includes a cylindrical sampler body 12 and a sealing cover 13 connected to the top and bottom of the sampler body 12. The sealing cover 13 and the sampler body 12 can be threaded, plug-in or other detachable connections, preferably threaded. The sampler body 12 is made of micron-level porous hard polyethylene. Groundwater and pollutants such as volatile organic compounds, semi-volatile organic compounds, and heavy metals dissolved in groundwater can enter the sampler body 12 through the micron-level pores in the side wall of the sampler body 12 under the action of groundwater pressure. The entire sampling process does not cause disturbance to the groundwater in the monitoring well, and the sample detection results can better characterize the pollution status of the groundwater on the site under natural conditions.

[0052] The bottom sealing cover 13 is provided with a sampling port 11. An airtight quick connector is threadedly connected at the sampling port 11, a section of Teflon tube is connected to the end of the airtight quick connector, and an airtight valve is connected to the end of the Teflon tube. The top and bottom sealing covers 13 are correspondingly provided with a first air duct interface 14 that cooperates with the air duct 3. The top sealing cover 13 is also provided with an exhaust port 15, and the exhaust port 15, the air duct 3 and the first air duct interface 14 at the top are connected through a three-way connector. The first air duct interface 14 and the exhaust port 15 are both threadedly connected with an airtight quick connector. In order to facilitate the connection between the fixing rope 4 and the sealing cover 13, the present invention is connected to the sealing cover 13 with a horseshoe connector by bolts, and a rubber gasket is provided between the horseshoe connector and the sealing cover 13. In addition, in order to ensure that the pressure difference driven passive groundwater stratification sampling device can maintain balance when lowered, a lead sinker 6 is connected to the bottom end of the sampler 1 at the bottom.

[0053] like Figure 4 and 5 As shown, the barrier diaphragm 21 is provided with a second airway interface 24 that cooperates with the airway 3. An airtight quick connector is threadedly connected at the second airway interface 24. A breathing valve 23 is bolted to the barrier diaphragm 21. In order to facilitate the connection between the fixing rope 4 and the barrier diaphragm 21, the present invention is connected to the barrier diaphragm 21 with a horseshoe connector by bolts, and similarly, a rubber gasket is provided between the horseshoe connector and the barrier diaphragm 21.

[0054] like Figure 6 and 7 As shown, a pressure difference driven passive groundwater stratified sampling system includes the above-mentioned pressure difference driven passive groundwater stratified sampling device, and also includes a well pipe device 7 and a filter material and barrier device 8.

[0055] The well pipe device 7 is vertically arranged along the center of the wellbore, including a solid pipe 71 and a screen pipe 72 connected vertically at intervals, and the top is the solid pipe 71. The solid pipe 71 and the screen pipe 72 can be connected by threaded connection, plug-in or other detachable methods. The top and bottom of the well pipe device 7 are respectively connected with a well cover 74 and a pipe plug 73. The pressure difference driven passive groundwater stratification sampling device is arranged in the well pipe device 7, and the top sampler 1 is connected to the well cover 74 by a fixed rope 4, and the sampler 1 and the stratification barrier 2 are respectively arranged in the screen pipe 72 and the solid pipe 71. The well cover 74 is fixed to the top of the well pipe device 7, that is, the top of the top solid pipe 71, in a socket-type manner. The pipe plug 73 and the bottom screen pipe 72 can be connected by threaded connection, plug-in or other detachable methods.

[0056] The filter material and barrier device 8 is arranged between the outer wall of the well pipe device 7 and the wellbore wall, and includes a filter material 81 and a barrier layer 82. The filter material 81 and the barrier layer 82 are arranged at intervals from bottom to top, and the topmost layer is the barrier layer 82. The filter material 81 is arranged between the outer wall of the screen tube 72 and the wellbore wall, and the top and bottom of the filter material 81 both exceed the screen tube 72. The top and bottom of the filter material 81 are preferably at least 0.3m beyond the screen tube 72 to ensure that the screen tube 72 is completely exposed to the aquifer from which the sample is to be collected. The filter material and barrier device 8 also includes a sealing layer 83, which is arranged between the outer wall of the well pipe device 7 and the wellbore wall at the top of the topmost barrier layer 82. The filter material 81 is preferably quartz sand, and the barrier layer 82 is preferably bentonite slurry. The sealing layer 83 is preferably cement slurry.

[0057] like Figure 8 and 9 As shown, the manhole cover 74 includes a cover plate and a cylindrical side wall, and a seal 75 is provided on the cover plate. An airtight quick connector is threadedly connected to the seal 75, a section of polytetrafluoroethylene tube is connected to the top of the airtight quick connector, an airtight valve is connected to the end of the polytetrafluoroethylene tube, and the bottom end of the airtight quick connector is connected to the air guide tube 3. In order to facilitate the connection between the manhole cover 74 and the fixing rope 4, the present invention has a horseshoe connector connected to the bottom of the cover plate by bolts, and a rubber gasket is provided between the horseshoe connector and the cover plate.

[0058] The method for sampling using the passive groundwater stratification sampling system driven by the pressure difference comprises the following steps:

[0059] Step 1: Based on the distribution of pollution facilities on site, historical monitoring data, on-site pollution traces and other information, screen and determine the groundwater sampling and testing points, use a drilling rig to drill wells at the determined groundwater sampling and monitoring points, and follow up with casing throughout the drilling process to prevent the side wall of the wellbore from collapsing.

[0060] Step 2: vertically install the well pipe device 7 in the wellbore, ensuring that the well pipe device 7 is located in the center of the wellbore.

[0061] Step three, fill the filter material and barrier device 8 between the outer wall of the well pipe device 7 and the wellbore wall, and fill the filter material 81 and the barrier layer 82 from bottom to top, and the barrier layer 82 is at the top to ensure that the filter material 81 is filled between the outer wall of the screen tube 72 and the wellbore wall. The filter material 81 is clean quartz sand, and the barrier layer 82 is bentonite mud. During the on-site filling process, clean quartz sand can be filled directly from the ground along the gap using a funnel. The bentonite mud needs to be adjusted into a mud state on the ground, and then transported directly to the filling depth through a pipeline using a mud pump. The bentonite mud is filled from bottom to top using the delivery pressure of the mud pump to ensure the integrity of the barrier layer 82.

[0062] Step 4: When the top barrier layer 82 is 0.3-0.5 m above the ground, stop loading the barrier layer 82, and then pour the sealing layer 83 between the outer wall of the well pipe device 7 and the wellbore wall at the top of the barrier layer 82 until the sealing layer 83 is 0.2-0.3 m above the ground.

[0063] Step 5: According to the designed sampling depth, the sampler 1 and the layered barrier 2 are connected from top to bottom at intervals, and the airtight valves on all sampling ports 11 are closed. In the process of connecting the sampler 1 and the layered barrier 2, from top to bottom, after one end of the fixing rope 4 connecting the top sampler 1 is connected and fixed to the sampler 1, the other end is connected and fixed to the horseshoe connector at the bottom of the manhole cover 74. From top to bottom, the lower end of the bottom sampler 1 is connected to the plumb bob 6 through the fixing rope 4.

[0064] Step six, after the layered barrier 2 and the one-way valve 5 are connected through the air pipe 3, the air pipe 3 is then connected to the sampler 1 from top to bottom, and the top of the air pipe 3 is connected to the airtight valve at the sealing port 75 of the manhole cover 74.

[0065] Step 7: Place the pressure-differential driven passive groundwater stratification sampling device connected to the top of the manhole cover 74 vertically into the well pipe device 7, fix the manhole cover 74 to the solid pipe 71 at the top of the well pipe device 7, open the airtight valve at the sealing port 75 on the manhole cover 74, and record the installation completion time.

[0066] Step 8: 15 days after the installation is completed, close the airtight valve at the sealing port 75 on the manhole cover 74, open the manhole cover 74, lift the fixing rope 4, and lift the sampler 1 and the layered barrier 2 to the ground.

[0067] Step 9: Open the airtight valve at the sampling port 11 at the bottom of the sampler 1, transfer the sample to a special sample bottle, and the sampling is completed. Place the sample bottle containing the groundwater sample in a sample insulation box, and transport it to the laboratory for pollutant concentration analysis and detection using the corresponding standard method.

[0068] The above embodiments are merely descriptions of preferred implementation modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A passive groundwater stratification sampling device driven by pressure difference, characterized in that include: The samplers (1) are arranged vertically at intervals, the samplers (1) are hollow structures and have pores on their side walls for pollutants to penetrate into the samplers (1), and the bottoms of the samplers (1) are provided with sampling ports (11); A layered barrier (2) is connected between adjacent samplers (1), the layered barrier (2) comprising a barrier diaphragm (21), the barrier diaphragm (21) being provided with a water hole (22) extending vertically therethrough, and a breathing valve (23) cooperating with the water hole (22) being connected to the barrier diaphragm (21) above the water hole (22); An air guide tube (3) is connected to all the samplers (1) and the layered barrier (2) in sequence, and a one-way valve (5) is provided on the air guide tube (3) to control the flow direction from bottom to top; The sampler (1) comprises a cylindrical sampler body (12) and a sealing cover (13) connected to the top and bottom of the sampler body (12); The barrier membrane (21) is provided with a second airway pipe interface (24) that cooperates with the airway pipe (3); The sampler (1) and the layered barrier (2) are connected via a fixing rope (4).

2. The pressure difference driven passive groundwater stratification sampling device according to claim 1, characterized in that: The sampler body (12) is made of micron-grade porous hard polyethylene, a sampling port (11) is provided on the bottom sealing cover (13), and first airway pipe interfaces (14) that cooperate with the airway pipe (3) are correspondingly provided on the top and bottom sealing covers (13).

3. The pressure-differential driven passive groundwater stratification sampling device according to claim 1, characterized in that: The sealing cover (13) at the top is also provided with an exhaust port (15), and the exhaust port (15), the air guide pipe (3) and the first air guide pipe interface (14) at the top are connected via a three-way joint.

4. The pressure-differential driven passive groundwater stratification sampling device according to claim 1, characterized in that: The bottom end of the bottommost sampler (1) is connected with a lead sinker (6).

5. A pressure difference driven passive groundwater stratification sampling system, characterized in that: A passive groundwater stratification sampling device driven by pressure difference according to any one of claims 1 to 4, further comprising: A well pipe device (7) is vertically arranged along the center of the wellbore, comprising a solid pipe (71) and a screen pipe (72) connected vertically at intervals, and the topmost portion is the solid pipe (71). The top and bottom portions of the well pipe device (7) are respectively connected to a well cover (74) and a pipe plug (73), and the well cover (74) is provided with a seal (75). The pressure difference-driven passive groundwater stratified sampling device is arranged in the well pipe device (7), and the topmost sampler (1) is connected to the well cover (74) via a fixing rope (4). The sampler (1) and the stratified barrier (2) are respectively arranged in the screen pipe (72) and the solid pipe (71); The filter material and barrier device (8) is arranged between the outer wall of the well pipe device (7) and the wellbore wall, and comprises a filter material (81) and a barrier layer (82). The filter material (81) and the barrier layer (82) are arranged at intervals from bottom to top, and the topmost layer is the barrier layer (82). The filter material (81) is arranged between the outer wall of the screen tube (72) and the wellbore wall, and the top and bottom of the filter material (81) both extend beyond the screen tube (72). The filter material and barrier device (8) further comprises a sealing layer (83), and the sealing layer (83) is arranged between the outer wall of the well pipe device (7) and the wellbore wall at the top of the topmost barrier layer (82).

6. The pressure difference driven passive groundwater stratification sampling system according to claim 5, characterized in that: The filter material (81) is quartz sand, the barrier layer (82) is bentonite slurry, and the sealing layer (83) is cement slurry.

7. The pressure difference driven passive groundwater stratification sampling system according to claim 5, characterized in that: The top and bottom of the filter material (81) both extend beyond the screen tube (72) by at least 0.3 m.

8. A method for sampling using the pressure difference driven passive groundwater stratification sampling system as claimed in any one of claims 5 to 7, characterized in that The following steps are involved: Step 1: determine the groundwater sampling and testing points and drill wells; Step 2: vertically install the well pipe device (7) in the wellbore, ensuring that the well pipe device (7) is located at the center of the wellbore; Step 3: Fill filter material and barrier device (8) between the outer wall of the well pipe device (7) and the wellbore wall, and fill filter material (81) and barrier layer (82) from bottom to top, with the barrier layer (82) at the top, to ensure that the filter material (81) is filled between the outer wall of the screen tube (72) and the wellbore wall; Step 4: When the top barrier layer (82) is 0.3-0.5 m above the ground, stop loading the barrier layer (82), and then pour the sealing layer (83) between the outer wall of the well pipe device (7) and the wellbore wall on the top of the barrier layer (82), until the sealing layer (83) is 0.2-0.3 m above the ground; Step 5: According to the designed sampling depth, the sampler (1) and the layered barrier (2) are connected from top to bottom in intervals, and all sampling ports (11) are closed; Step 6: After the layer barrier (2) and the one-way valve (5) are connected through the air guide tube (3), the air guide tube (3) is connected to the sampler (1) from top to bottom, and the top of the air guide tube (3) is connected to the manhole cover (74); Step 7: vertically place the pressure difference driven passive groundwater stratification sampling device connected to the well cover (74) at the top into the well pipe device (7), fix the well cover (74) to the solid pipe (71) at the top of the well pipe device (7), open the seal (75) on the well cover (74), and record the installation completion time; Step 8: 15 days after the installation is completed, close the seal (75) on the manhole cover (74), open the manhole cover (74), and lift the sampler (1) and the layer barrier (2) to the ground; Step 9: Open the sampling port (11) at the bottom of the sampler (1) and transfer the sample into a dedicated sample bottle. Sampling is now complete.

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