Deep-sea mining plume metal concentration continuous monitoring device and method

Abstract

The invention provides a deep-sea mining plume metal concentration continuous monitoring device and method, and belongs to the technical field of variable measurement methods, the adopted continuous monitoring device comprises a shell and a rotary table, and a plurality of fixing grooves are formed in the rotary table in the circumferential direction; the DGT passive sampling unit is assembled in the fixing groove, and the driving mechanism is used for driving the turntable to rotate around a shaft; the continuous monitoring method comprises the following steps: step 1, controlling the driving mechanism to drive the turntable to rotate; 2, recycling the continuous monitoring device; 3, taking out an adsorption layer of the DGT passive sampling unit; 4, measuring the concentration of metal ions in the eluent; and 5, calculating the mass of the metal ions accumulated in the adsorption layer of each DGT passive sampling unit. According to the method, the equipment and operation cost is reduced, meanwhile, manual intervention is reduced, the sample pollution risk is avoided, the technical method capable of accurately calculating the metal ion concentration in the plume is provided, and the accuracy and reliability of monitoring data are ensured.

Description

Technical Field

[0001] The present invention relates to a method for measuring metal concentration, and in particular to a device and method for continuously monitoring the metal concentration of deep-sea mining plumes. Background Art

[0002] As deep-sea mining activities increase, the plumes generated by the mining process may have long-term impacts on the marine ecosystem. The plumes contain large amounts of suspended particles and metal ions. If these metal ions are concentrated in high concentrations, they can be toxic to marine life and seriously affect the ecosystem.

[0003] Currently, methods for monitoring metal ions in deep-sea plumes primarily fall into two categories: in situ water sampling and laboratory analysis, and passive sampling using Diffusive Gradients in Thin Films (DGT). Traditional in situ water sampling relies on deep-sea samplers to collect water samples at a target depth. The samples are then brought back to the laboratory for quantitative analysis using instruments such as ICP-MS (inductively coupled plasma mass spectrometry) or AAS (atomic absorption spectrometry). While these methods offer high sensitivity and accuracy, they suffer from significant drawbacks: First, they cannot achieve long-term continuous monitoring and can only obtain concentrations at specific points in time. Second, the numerous transfer steps involved in water sample collection, recovery, and analysis make them susceptible to contamination or compositional changes, compromising the reliability of analytical results. Third, the high operational costs make them unsuitable for use in extreme sea conditions. To overcome these challenges, passive sampling technology, DGT, has recently been introduced for deep-sea environmental monitoring. DGT utilizes adsorption and diffusion layers to achieve time-accumulated acquisition of dissolved metal ions, offering advantages such as high selectivity and minimal background interference. However, existing DGT devices are typically only capable of one-time, short-term sampling. Repeated deployment is required for multiple sampling runs, increasing both the complexity of the equipment and the risk of offshore operations. Furthermore, traditional DGTs cannot automatically control exposure duration, requiring manual recording of sampling times, further limiting their breadth and timeliness in deep-sea plume monitoring. Summary of the Invention

[0004] In order to solve the technical problem that the metal concentration of deep-sea mining plumes cannot be continuously monitored in the existing deep-sea mining process, the present invention proposes a method for continuously monitoring the metal concentration of deep-sea mining plumes, which can solve the above problem.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions: A device for continuously monitoring metal concentration in deep-sea mining plumes, comprising: A housing is formed with a receiving space therein, and a sampling port is provided through the bottom of the housing; a turntable disposed in the housing and tightly fitted with the bottom of the housing, the turntable being provided with a plurality of fixing grooves along a circumferential direction, the fixing grooves having notches opening toward the bottom of the housing; A plurality of DGT passive sampling units are provided, each comprising an adsorption layer, a diffusion layer, and a filter membrane arranged from the inside out. The DGT passive sampling unit is assembled in the fixed groove, and the filter membrane of the DGT passive sampling unit is oriented in the same direction as the groove opening. The driving mechanism is used to drive the turntable to rotate around the axis so that one of the slots is aligned with the sampling port as a collection slot. The filter membrane of the DGT passive sampling unit located in the collection slot is in contact with the external seawater to accumulate and collect metal ions in the seawater.

[0006] In some embodiments, one or more fixing rings are provided on the outer surface of the housing.

[0007] In some embodiments, a fixing ring is respectively provided on the upper surface and the lower surface of the shell.

[0008] In some embodiments, the fixing ring is made of titanium alloy.

[0009] In some embodiments, the turntable is a circular disc.

[0010] In some embodiments, the shell is made of corrosion-resistant and pressure-resistant material.

[0011] In some embodiments, the housing is further provided with: A main control and power supply unit, which is used to control the operation of the driving mechanism and provide power to the driving mechanism; Data recording module, which is used to record the start and end time of exposure sampling of each DGT passive sampling unit; USB communication interface, used for communicating with the outside world.

[0012] The present invention also proposes a method for continuous monitoring of metal concentration in deep-sea mining plumes. The method is based on the aforementioned device for continuous monitoring of metal concentration in deep-sea mining plumes. The method comprises: Step 1: Control the drive mechanism to drive the turntable to rotate according to the set exposure time t, and each rotation angle makes the next adjacent slot align with the sampling port, and record the start and end time of exposure sampling of each DGT passive sampling unit; Step 2: After all DGT passive sampling units have completed cumulative collection, the continuous monitoring device is recovered, the DGT passive sampling unit is removed from the fixed tank, and the filter membrane surface is rinsed with distilled water to remove attachments; Step 3: Take out the adsorption layer of the DGT passive sampling unit, place it in a clean sample tube, add HNO3 solution, and soak it for 24 hours to elute the adsorbed metal ions; Step 4: Determine the metal ion concentration C in the eluate e ; Step 5: Calculate the metal ion mass M accumulated in the adsorption layer of each DGT passive sampling unit: ; Among them, V HNO3 is the volume of HNO3 solution, V gel is the volume of the adsorption layer, f e is the elution factor; Step 6: Calculate the average concentration C during the sampling time interval of the DGT passive sampling unit based on the metal ion mass M, diffusion coefficient D, effective exposure area A, and exposure time t: ; Where Δg is the total thickness of the diffusion layer and the filter membrane.

[0013] In some embodiments, in step 4, the metal ion concentration C in the eluent is determined using a mass spectrometer ICP-MS or an atomic absorption spectrometer AAS. e .

[0014] In some embodiments, the elution factor fe in step five is 0.8.

[0015] Compared with the prior art, the advantages and positive effects of the present invention are as follows: the method for continuous monitoring of metal concentration in deep-sea mining plumes of the present invention is achieved by arranging a turntable in the outer shell, and a plurality of fixed slots are opened on the turntable along the circumferential direction. A DGT passive sampling unit can be arranged in each fixed slot, and at most one DGT passive sampling unit's filter membrane is aligned with the sampling port at the bottom of the outer shell at a time, and then the filter membrane of the DGT passive sampling unit contacts the seawater to achieve passive sampling. The driving mechanism switches the DGT passive sampling unit for sampling by driving the turntable to rotate, thereby achieving long-term and stable monitoring of plume metal concentration in the complex environment of the deep sea. This solution reduces equipment and operating costs, while reducing manual intervention, avoiding the risk of sample contamination, and providing a technical method that can accurately calculate the concentration of metal ions in the plume, ensuring the accuracy and reliability of the monitoring data.

[0016] Other features and advantages of the present invention will become more apparent after reading the detailed description of the embodiments of the present invention in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 12 is a schematic structural diagram of an embodiment of a method for continuous monitoring of metal concentration in a deep-sea mining plume proposed by the present invention; Figure 2 yes Figure 1 Schematic side view of Figure 3 yes Figure 1 Schematic diagram of the internal structure; Figure 4 yes Figure 1 Schematic diagram of the internal local structure; Figure 5 This is a graph showing a continuous monitoring curve of metal concentration in a deep-sea mining plume according to an embodiment of the method for continuous monitoring of metal concentration in a deep-sea mining plume proposed by the present invention; Figure 6 Schematic diagram of a DGT passive sampling unit in an embodiment of the method for continuous monitoring of metal concentration in deep-sea mining plumes proposed by the present invention; In the figure: 11, housing; 110, sampling port; 111, upper fixing ring; 112, lower fixing ring; 12, turntable; 120, fixing slot; 121, driven disk; 122, driving disk; 123, rotating shaft; 13, DGT passive sampling unit; 15, power supply unit; 16, fixed base. DETAILED DESCRIPTION

[0018] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0019] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0020] It should be noted that, in the description of the present invention, the terms "upper", "lower", "left", "right", "vertical", "horizontal", "inside", "outside" and the like indicating directions or positional relationships are based on the directions or positional relationships shown in the accompanying drawings. This is merely for the convenience of description and does not indicate or imply that the device or element must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it cannot be understood as a limitation on 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. In the description of the present invention, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined.

[0021] In the present invention, unless otherwise expressly specified or limited, the terms "mounted," "connected," "connect," "fixed," etc. should be understood broadly. For example, they may refer to fixed connection, detachable connection, or integration; mechanical connection or electrical connection; direct connection or indirect connection through an intermediate medium; internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0022] Example 1, see Figure 1-Figure 4 As shown, this embodiment proposes a deep-sea mining plume metal concentration continuous monitoring device. The continuous monitoring method is implemented using the deep-sea mining plume metal concentration continuous monitoring device. The continuous monitoring device includes a shell 11, a turntable 12, a DGT passive sampling unit 13 and a driving mechanism. A accommodating space is formed inside the shell 11, and a sampling port 110 is opened at the bottom of the shell 11 and passes through the inside and outside of the shell 11.

[0023] The turntable 12 is disposed in the housing 11 and fits tightly against the bottom of the housing 11 . A plurality of fixing slots 120 are formed on the turntable 12 along a circumferential direction. The fixing slots 120 have slots opening toward the bottom of the housing.

[0024] The DGT passive sampling unit 13 has multiple components, including an adsorption layer, a diffusion layer, and a filter membrane arranged from the inside to the outside. The DGT passive sampling unit 13 is assembled in the fixed groove 120, and the filter membrane of the DGT passive sampling unit is oriented in the same direction as the groove. At most one filter membrane of the DGT passive sampling unit is aligned with the sampling port 110 at the bottom of the shell at a time, and then the filter membrane of the DGT passive sampling unit 13 contacts the seawater to realize passive sampling.

[0025] The driving mechanism is used to drive the turntable 12 to rotate, so that the slot of one of the fixed slots 120 and the sampling port 110 serve as the collection slot, and the filter membrane of the DGT passive sampling unit located in the collection slot contacts the external seawater to accumulate and collect metal ions in the seawater.

[0026] The method for continuous monitoring of metal concentration in deep-sea mining plumes of this embodiment is achieved by disposing a turntable within a housing with a plurality of fixed slots formed circumferentially thereon. A DGT passive sampling unit can be disposed in each fixed slot, and at most one DGT passive sampling unit's filter membrane is aligned with the sampling port at the bottom of the housing at a time, so that the filter membrane of the DGT passive sampling unit contacts the seawater to achieve passive sampling. The drive mechanism drives the turntable to rotate, switching the DGT passive sampling unit for sampling, thereby enabling long-term and stable monitoring of plume metal concentrations in complex deep-sea environments. This solution reduces equipment and operating costs, while also reducing manual intervention and avoiding the risk of sample contamination. It also provides a technical method for accurately calculating metal ion concentrations in plumes, ensuring the accuracy and reliability of monitoring data.

[0027] To protect the DGT passive sampling unit from seawater intrusion during non-sampling periods and prevent background adsorption during unspecified time periods, which could affect data accuracy, an O-ring seal is placed around each fixed slot. When the turntable is in the non-sampling position, the DGT unit forms a static pressure seal with the inner wall of the housing through the O-ring. This system ensures that each DGT unit maintains a stable, watertight seal as the turntable rotates to the next sampling unit after each DGT unit is exposed.

[0028] In some embodiments, the outer surface of the housing 11 is provided with one or more fixing rings for connecting an anchor line.

[0029] In some embodiments, a fixing ring is provided on the upper surface and the lower surface of the shell 11, namely an upper fixing ring 111 and a lower fixing ring 112. The upper fixing ring 111 is located at the top of the shell and is used to connect the anchor line. The lower fixing ring 112 is located at the bottom of the shell to ensure that the monitoring device is firmly fixed in the deep sea environment.

[0030] In some embodiments, housing 11 is a rectangular parallelepiped structure, constructed from high-strength, corrosion-resistant materials to withstand the high pressures and low temperatures of the deep sea. Housing 11 employs a sealed design with a sealing ring to prevent seawater from seeping into the device, ensuring the long-term stable operation of the internal electronic components and mechanical structure.

[0031] The sampling port 110 is provided at the bottom of the housing 11 and communicates with the interior of the housing 11, ensuring that the DGT sampling unit can fully contact the external water. The bottom of the housing 11 can be made of high-strength material to ensure the structural stability of the device in deep-sea environments.

[0032] In some embodiments, the fixing ring is made of titanium alloy material, which has high strength and corrosion resistance and can withstand deep-sea high pressure and strong water flow impact.

[0033] In some embodiments, the turntable 12 is a circular disk. A plurality of DGT passive sampling units 13 are equidistantly mounted in fixed slots 120 on the turntable 12 to ensure that the turntable 12 remains stable during rotation.

[0034] In order to improve the sealing performance between the turntable 12 and the housing 11 and facilitate the setting of the driving mechanism, in some embodiments, the turntable 12 includes a driven disk 121 and a driving disk 122, and the fixing groove 120 is opened near the edge of the driven disk 121, and the multiple fixing grooves 120 are arranged around the edge of the driven disk 121.

[0035] The driven disk 121 is made of high-strength, corrosion-resistant materials to ensure long-term stable operation in deep-sea environments. The DGT passive sampling unit 13 is used to accumulate metal ions in the plume and is the core sampling component of the equipment. The equipment is usually equipped with 12 passive sampling units, which can be adjusted according to needs. The driving disk 122 is fixedly installed at the center position of the upper surface of the driven disk 121. The driving disk 122 is the core mechanical component of the equipment. The driving disk 122 can drive the driven disk 121 to rotate, exposing multiple DGT passive sampling units 13 in turn. The driving disk 122 is made of high-strength, corrosion-resistant materials to ensure long-term stable operation in deep-sea environments.

[0036] The driving mechanism is fixedly installed at the center of the driving disk 122 . The driving mechanism can be implemented by a rotary motor. The driving mechanism is controlled by the main control and power supply unit 15 .

[0037] like Figure 3 As shown, the main control and power supply unit 15 is supported in the housing 11 via a fixed base 16 .

[0038] The DGT passive sampling unit 13 includes an adsorption layer, a diffusion layer, and a filter membrane, arranged sequentially from the inside out. A drive mechanism rotates the driven disk 121, aligning one of its slots with the sampling port 110 as the collection slot. The sampling port 110 and the filter membrane of the DGT passive sampling unit 13 located in the collection slot are in a vertically connected position. During operation, the sampling port 110 and the filter membrane of one of the DGT passive sampling units 13 in the driven disk 121 align with the sampling port 110, allowing the DGT membrane to contact seawater and accumulate metal ions. The remaining unexposed DGT passive sampling units remain sealed and cannot contact seawater.

[0039] When the DGT passive sampling unit 13 in the collection slot meets the exposure time t, the drive mechanism drives the turntable 12 to rotate, and the new clean DGT passive sampling unit will rotate to the sampling port 110 position, come into contact with the seawater, and begin to accumulate metal ions, while the previously exposed DGT membrane is sealed and sampling stops. Repeat the above steps until all DGT passive sampling units have completed sampling. This solution can achieve long-term continuous sampling and monitoring of metal ions, and is fully automated, avoiding the frequent throwing and collecting of sampling devices by manpower.

[0040] The DGT diffusion gradient film is a passive sampling technology particularly suitable for measuring dissolved metals and other substances in water. The DGT device has two core layers: a diffusion layer and an adsorption layer. The diffusion layer consists of a hydrogel that allows metal ions to diffuse, while the film blocks other impurities. The adsorption layer contains chemicals that bind to metal ions, capturing and immobilizing them.

[0041] like Figure 6 As shown, when the DGT passive sampling unit is placed in water, metal ions in the water, such as iron, manganese, and nickel, enter the DGT diffusion layer and diffuse through the hydrogel and filter membrane layers. The diffusion rate depends on the concentration difference in the water. This is like forming a concentration gradient in the water, with metal ions diffusing from areas with high concentrations in the water to areas with low concentrations in the DGT passive sampling unit. After the metal ions pass through the diffusion layer, they are captured by the chemicals in the adsorption layer and accumulate in the adsorption layer. The DGT passive sampling unit is like a sponge, capable of absorbing metal ions in the water. The amount of water absorbed by the sponge is proportional to the concentration of the metal ions in the water and the time. The longer the time, the more metal ions the sponge absorbs.

[0042] This embodiment is equipped with 12 DGT passive sampling units, and the exposure time of each DGT unit can be set independently. The rotating shaft 123 connects the drive disk 122 and the rotary motor. The motor is controlled by the main control system and rotates at preset time intervals. After each rotation, a new sampling unit is exposed to the external water body and begins to accumulate metal ions. The rotary design can expose each sampling unit in turn, ensuring that the changes in metal concentration in the plume at different time periods are captured during long-term monitoring.

[0043] After deploying the deep-sea mining plume metal concentration continuous monitoring device for a period of time, the device is recovered. In the laboratory, chemical solutions can be used to dissolve the metal ions on the adsorption layer and measure the concentration of these metals.

[0044] In some embodiments, the housing is further provided with: A main control and power supply unit, which is used to control the operation of the drive mechanism and provide power to the drive mechanism; Data recording module, which is used to record the start and end time of exposure sampling of each DGT passive sampling unit; USB communication interface, used for communicating with the outside world.

[0045] Example 2: This example proposes a method for continuous monitoring of metal concentration in deep-sea mining plumes. The method is based on the device for continuous monitoring of metal concentration in deep-sea mining plumes described in Example 1. The continuous monitoring method includes: Step 1: Control the driving mechanism to drive the turntable to rotate according to the set exposure time t, and each rotation angle makes the next adjacent slot align with the sampling port, thereby switching the DGT passive sampling unit for sampling and recording the start and end time of exposure sampling of each DGT passive sampling unit.

[0046] Step 2: After all DGT passive sampling units have completed cumulative collection, the continuous monitoring device is recovered, the DGT passive sampling unit is taken out from the fixed tank, and the filter membrane surface is rinsed with distilled water to remove attachments.

[0047] Step 3: Take out the adsorption layer of the DGT passive sampling unit, place it in a clean sample tube, add HNO3 solution, and soak it for 24 hours to elute the adsorbed metal ions.

[0048] Step 4: Determine the metal ion concentration C in the eluate e .

[0049] Step 5: Calculate the metal ion mass M accumulated in the adsorption layer of each DGT passive sampling unit: .

[0050] Among them, V HNO3 is the volume of HNO3 solution, V gel is the volume of the adsorption layer, f e is the elution factor.

[0051] Step 6: Calculate the average concentration C during the sampling time interval of the DGT passive sampling unit based on the metal ion mass M, diffusion coefficient D, effective exposure area A, and exposure time t: .

[0052] Where Δg is the total thickness of the diffusion layer and the filter membrane.

[0053] The diffusion coefficient D is a known parameter obtained in advance.

[0054] In some embodiments, in step 4, the metal ion concentration C in the eluent is determined using a mass spectrometer ICP-MS or an atomic absorption spectrometer AAS. e .

[0055] In some embodiments, the elution factor fe in step 5 is 0.8.

[0056] In this embodiment, the concentration of metals in water can be calculated based on the exposure time of the deep-sea mining plume metal concentration continuous monitoring device, the diffusion rate of metals and other information, thereby realizing continuous monitoring of the metal concentration of deep-sea mining plumes.

[0057] The method for continuous monitoring of metal concentration in deep-sea mining plumes of this embodiment further includes the following steps: Equipment preparation: Store the DGT passive sampling unit 13 in a sealed clean plastic bag containing a small amount of 0.01M NaNO3 solution to keep it moist. Before deployment, check whether the DGT passive sampling unit 13 is in a moist state and add a small amount of NaNO3 solution if necessary.

[0058] Install the DGT passive sampling units 13 into the fixed slots of the driven disk 121 one by one, with the positive filter membrane of each DGT passive sampling unit 13 facing outward to prevent the filter membrane from contacting any contaminants. Check that the drive disk 122 and the rotating shaft 123 are operating properly to ensure that the DGT passive sampling units 13 can be switched smoothly.

[0059] Connect the main control and power supply unit to a computer via USB. Set the exposure time t and sampling frequency for the DGT passive sampling unit 13. The main control system supports programmable control to ensure that each sampling unit is exposed according to the preset time. Start the device and check whether the main control system is operating normally.

[0060] Equipment Installation: The device is deployed in a deep-sea mining area using a mooring line or a seabed support. Upper and lower retaining rings 111 and 112 on the housing 11 secure the device to the anchor, ensuring stability in deep-sea environments. The sampling port 110 faces downward to prevent particulate matter from settling on the surface of the sampling unit.

[0061] Device startup: After the device is started, the main control and power supply unit controls the drive disk 122 to rotate at a preset time interval, exposing each DGT passive sampling unit 13 in turn; each DGT passive sampling unit 13 begins to accumulate metal ions in the plume during the exposure period.

[0062] Equipment recycling: After sampling, the device was recovered from the deep-sea environment; the DGT passive sampling unit 13 was immediately taken out, and the filter membrane surface was rinsed with distilled water to remove attachments; the DGT passive sampling unit 13 was sealed in a clean plastic bag, marked with the sampling time and location, and stored in a refrigerator at 4°C, awaiting laboratory analysis.

[0063] Laboratory analysis: Remove the adsorption layer of the DGT passive sampling unit 13, place it in a clean sample tube, add 1 ml of 1M HNO3 solution, and soak for 24 hours to elute the adsorbed metal ions; use a mass spectrometer ICP-MS or an atomic absorption spectrometer AAS to measure the metal ion concentration C in the eluate. e .

[0064] Cumulative mass calculation: The average concentration C in the sampling time interval of each DGT passive sampling unit is calculated according to steps 5 and 6. Since the sampling time interval of each DGT passive sampling unit is continuous, continuous monitoring of the metal concentration of deep-sea mining plumes can be achieved.

[0065] like Figure 5 As shown in the figure, the dissolved copper concentration in a certain offshore waters showed a fluctuating upward trend throughout the monitoring period, with the highest value occurring on the 19th (4.0 µg / L) and the lowest value occurring on the 7th (2.1 µg / L).

[0066] Of course, the above description is not a limitation of the present invention, and the present invention is not limited to the above examples. Changes, modifications, additions or substitutions made by ordinary technicians in this technical field within the essential scope of the present invention should also fall within the scope of protection of the present invention.

Claims

1. A device for continuous monitoring of metal concentration in deep-sea mining plumes, characterized in that ,include: A housing is formed with a receiving space therein, and a sampling port is provided through the bottom of the housing; a turntable disposed in the housing and tightly fitted with the bottom of the housing, the turntable being provided with a plurality of fixing grooves along a circumferential direction, the fixing grooves having notches opening toward the bottom of the housing; A plurality of DGT passive sampling units are provided, each comprising an adsorption layer, a diffusion layer, and a filter membrane arranged from the inside out. The DGT passive sampling unit is assembled in the fixed groove, and the filter membrane of the DGT passive sampling unit is oriented in the same direction as the groove opening. The driving mechanism is used to drive the turntable to rotate around the axis so that one of the slots is aligned with the sampling port as a collection slot. The filter membrane of the DGT passive sampling unit located in the collection slot is in contact with the external seawater to accumulate and collect metal ions in the seawater.

2. The deep-sea mining plume metal concentration continuous monitoring device according to claim 1 is characterized in that , one or more fixing rings are provided on the outer surface of the shell.

3. The deep-sea mining plume metal concentration continuous monitoring device according to claim 2 is characterized in that , a fixing ring is respectively provided on the upper surface and the lower surface of the shell.

4. The deep-sea mining plume metal concentration continuous monitoring device according to claim 2 is characterized in that ,The fixing ring is made of titanium alloy.

5. The deep-sea mining plume metal concentration continuous monitoring device according to claim 1 is characterized in that , the turntable is a circular disc.

6. The deep-sea mining plume metal concentration continuous monitoring device according to claim 1 is characterized in that ,The shell is made of corrosion-resistant and pressure-resistant materials.

7. The deep-sea mining plume metal concentration continuous monitoring device according to any one of claims 1 to 6, characterized in that , the housing is further provided with: A main control and power supply unit, which is used to control the operation of the driving mechanism and provide power to the driving mechanism; Data recording module, which is used to record the start and end time of exposure sampling of each DGT passive sampling unit; USB communication interface, used for communicating with the outside world.

8. A method for continuous monitoring of metal concentration in deep-sea mining plumes, characterized in that The continuous monitoring method is implemented based on the deep-sea mining plume metal concentration continuous monitoring device according to any one of claims 1 to 7, and the continuous monitoring method comprises: Step 1: Control the drive mechanism to drive the turntable to rotate according to the set exposure time t, and each rotation angle makes the next adjacent slot align with the sampling port, and record the start and end time of exposure sampling of each DGT passive sampling unit; Step 2: After all DGT passive sampling units have completed cumulative collection, the continuous monitoring device is recovered, the DGT passive sampling unit is removed from the fixed tank, and the filter membrane surface is rinsed with distilled water to remove attachments; Step 3: Take out the adsorption layer of the DGT passive sampling unit, place it in a clean sample tube, add HNO3 solution, and soak it for 24 hours to elute the adsorbed metal ions; Step 4: Determine the metal ion concentration C in the eluate e ; Step 5: Calculate the metal ion mass M accumulated in the adsorption layer of each DGT passive sampling unit: ； Among them, V HNO3 is the volume of HNO3 solution, V gel is the volume of the adsorption layer, f e is the elution factor; Step 6: Calculate the average concentration C during the sampling time interval of the DGT passive sampling unit based on the metal ion mass M, diffusion coefficient D, effective exposure area A, and exposure time t: ； Where Δg is the total thickness of the diffusion layer and the filter membrane.

9. The method for continuous monitoring of metal concentration in deep-sea mining plumes according to claim 8, characterized in that In step 4, the metal ion concentration C in the eluent is determined using a mass spectrometer ICP-MS or an atomic absorption spectrometer AAS. e .

10. The method for continuous monitoring of metal concentration in deep-sea mining plumes according to claim 8, characterized in that , the elution factor fe in step five is 0.8.

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