Microplastic sampling equipment and sampling methods, microplastic mass flux monitoring methods

Abstract

The present application relates to a microplastic sampling device and a sampling method, and a microplastic mass flux monitoring method. The sampler includes a water inlet unit, a filter unit, a replacement mechanism, and a collection mechanism. The filter unit includes a filter screen cover, one end of the filter screen cover is open, and the other end is closed. The open end of the filter screen cover is connected to the water inlet unit, and the filter screen cover is used to retain microplastics in filtered water. The replacement mechanism is arranged on the side of the filter screen cover close to the water inlet unit. The collection mechanism is connected to the closed end of the filter screen cover. The water inlet unit is used to pump water into the filter screen cover, and the microplastics in the water are retained in the filter screen cover, and the filtered water is directly discharged from the mesh of the filter screen cover. When replacing the filter screen cover, the collection mechanism collects the filter screen cover in a saturated state, and the replacement mechanism provides the filter screen cover in an unused state, thereby realizing the direct replacement of the filter screen cover, and further improving the sustainable use of the microplastic sampling device.

Description

Technical Field

[0001] The present application relates to the technical field of water quality monitoring, and in particular to microplastic sampling equipment and sampling methods, and microplastic mass flux monitoring methods. Background Art

[0002] Microplastics generally refer to plastic particles with a diameter of less than 5 mm. Measuring microplastic pollution in rivers helps to measure river quality.

[0003] In the relevant technologies, most plastic pollutant sampling methods rely mainly on manual operations, such as using nets to drag the surface or directly sampling from rivers. These methods are affected by many factors such as the experience of the sampling personnel, weather conditions, and river flow rate, so the results often have large deviations. In addition, the sampling methods in the relevant technologies are often based on the results of a single sampling, and are inferred through certain statistical methods and models. However, due to changes in factors such as river flow and weather conditions, a single sampling is difficult to represent the actual situation over a long period of time or over a large area.

[0004] However, when using net sampling, only single-point sampling can be achieved, and continuous sampling at multiple points cannot be achieved. In addition, the sampling method is difficult to represent the actual situation over a long period of time or over a large area, resulting in low accuracy in the detection results of microplastic mass flux in rivers. Summary of the invention

[0005] Based on this, it is necessary to provide a microplastic sampling equipment and sampling method, and a microplastic mass flux monitoring method to address the problem of low accuracy of river mass flux detection results.

[0006] A microplastic mass flux sampling device, the microplastic sampling device comprising a sampler, the sampler comprising:

[0007] Water inlet unit;

[0008] The filter unit comprises a filter screen cover, one end of the filter screen cover is open and the other end is closed, the open end of the filter screen cover is connected to the water inlet unit, the water inlet unit is used to suck water into the filter screen cover, and the filter screen cover is used to intercept microplastics in the water;

[0009] a replacement mechanism, disposed on a side of the filter screen cover close to the water inlet unit, for providing the filter screen cover in an unused state so that the filter screen cover in an unused state is connected to the water inlet unit; and

[0010] The collecting mechanism is connected to the closed end of the filter screen cover and is used for collecting the filter screen cover in a saturated state.

[0011] In one embodiment, the unused filter screen cover and the saturated filter screen cover are respectively connected to a portion of the filter screen cover, and the unused filter screen cover and the saturated filter screen cover are respectively located at two ends of the filter screen cover;

[0012] The replacement mechanism includes a filter box, which is mounted outside the water outlet of the water inlet unit. The unused filter cover is located in the filter box. A filter cover outlet is provided at one end of the filter box close to the collecting mechanism, and the saturated filter cover is wound around the collecting mechanism.

[0013] In one embodiment, the sampler includes a bracket, one end of which is connected to the water inlet unit or the replacement mechanism, and the other end of which is connected to the collection mechanism, and the bracket is used to support the filter screen cover.

[0014] In one embodiment, the collecting mechanism comprises a strapping machine, which is arranged at an exit position of the replacing mechanism and outside the filter screen cover.

[0015] In one embodiment, the microplastic sampling device includes at least a first pressure sensor and a second pressure sensor. The first pressure sensor is located outside the sampler and is used to detect the water depth of the sampler. The second pressure sensor is located inside the filter screen cover and is used to detect the pressure inside the filter screen cover.

[0016] In one embodiment, the microplastic sampling equipment also includes a hull and a line-retracting and -releasing mechanism disposed on the hull, a cable is wound around the line-retracting and -releasing mechanism, and the sampler is connected to the hull via the cable.

[0017] A microplastic sampling method, wherein the sampler is connected to the hull via a cable, and the sampling method comprises the following steps:

[0018] S1. Select the target section of the river and divide the target section into i layers along the depth direction, where i is a positive integer;

[0019] S2, driving the boat to the first side bank of the target section of the river, lowering the sampler to the first target depth through the cable, and turning on the sampler, and moving the sampler from the first side bank of the river to the second side bank along the target section through the boat;

[0020] S3, lowering the sampler to the target depth of layer 2 by using the cable, and driving the sampler along the target section from the second side bank of the river to the first side bank by using the hull;

[0021] S4, lowering the sampler to the target depth of layer 3 by using the cable, and moving the sampler from the first bank of the river to the second bank along the target section by using the hull;

[0022] S5. Repeat steps S3 and S4, and increase the number of target depth layers in sequence, until the acquisition of the i-th target depth layer is completed.

[0023] In one embodiment, the microplastic sampling device includes a bundling machine. After each layer of sampling at the target depth is completed, the open end of the filter mesh cover in a saturated state is tightened by the bundling mechanism, the collecting mechanism collects the filter mesh cover in a saturated state, and the replacement mechanism provides an unused filter mesh cover.

[0024] In one embodiment, the microplastic sampling device includes at least a first pressure sensor and a second pressure sensor, wherein the first pressure sensor is located outside the sampler and the second pressure sensor is located inside the filter screen;

[0025] When the pressure of the second pressure sensor is greater than or equal to 3 times the pressure of the first pressure sensor, the hull stops running, the water inlet unit is closed, the collecting mechanism collects the saturated filter mesh cover, the replacement mechanism provides the unused filter mesh cover, and then the hull and the water inlet unit are started simultaneously.

[0026] In one embodiment, a river is sampled by the microplastic sampling method described in any one of claims 7 to 9 to obtain microplastic samples at each target depth;

[0027] By formula Calculate the mass of plastic per unit volume of water sample at each target depth, where m i is the mass of the i-th plastic particle in a layer of water sample, and v is the volume of the water sample;

[0028] By formula Calculate the plastic mass flux of the target section, where K is the plastic mass flux of the section, MV is the product of the plastic mass per unit volume of water in a layer of water sample and the average flow velocity of the corresponding layer of water, surface is the river surface, and bed is the riverbed.

[0029] The above-mentioned microplastic sampling equipment and sampling method, and microplastic mass flux monitoring method, when actually used, can place the sampler in a river, and the water inlet unit is used to pump water into the filter screen cover, and the microplastics in the water are retained in the filter screen cover, and the filtered water is directly discharged from the mesh of the filter screen cover, thereby realizing real-time and continuous sampling of microplastics. The open end of the filter screen cover is connected to the replacement mechanism, and the closed end of the filter screen cover is connected to the collection mechanism. When the filter screen cover is used for a long time, microplastics easily clog the mesh on the filter screen cover, making it difficult for water to be discharged. At this time, the filter screen cover has reached a saturated state and needs to be replaced again. When replacing, the collection mechanism can collect the filter screen cover in a saturated state, and the filter screen cover in an unused state is provided by the replacement mechanism, so that the filter screen cover can be directly replaced, further improving the sustainable use of the microplastic sampling equipment. That is, the microplastic sampling equipment of the present application can realize continuous sampling in the river and improve the accuracy of sampling. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 Schematic diagram of the structure of a microplastic sampling device in one embodiment.

[0031] Figure 2 Schematic diagram of the structure of a sampler in one embodiment.

[0032] Figure 3 Schematic diagram of the cross-sectional structure of a river in one embodiment.

[0033] Figure numerals: 10, sampler; 20, hull; 30, cable; 40, line-retracting and -releasing mechanism; 50, antenna; 60, flow meter; 100, water inlet unit; 110, water pump; 120, water inlet pipe; 130, water inlet grille; 200, filter screen; 300, replacement mechanism; 310, filter screen outlet; 400, collecting mechanism; 500, strapping machine; 600, first pressure sensor; 700, bracket; 800, second pressure sensor; 210, first side shore; 220, second side shore; 230, first layer target depth; 240, second layer target depth; 250, i-th layer target depth. DETAILED DESCRIPTION

[0034] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present application, so the present application is not limited by the specific embodiments disclosed below.

[0035] In the description of the present application, it should be understood that if the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. appear, the orientation or position relationship indicated by these terms is based on the orientation or position relationship shown in the accompanying drawings, which is only for the convenience of describing the present application and simplifying the description, and does 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 a limitation on the present application.

[0036] In addition, if the terms "first" or "second" appear, these terms are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of this application, if the term "plurality" appears, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0037] In this application, unless otherwise clearly specified and limited, if the terms "installed", "connected", "connected", "fixed" and the like appear, these terms should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integrated connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to the specific circumstances.

[0038] In the present application, unless otherwise clearly specified and limited, if there is a description that a first feature is "above" or "below" a second feature, etc., or similar descriptions appear, it may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. Moreover, the first feature being "above", "above" and "above" the second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. The first feature being "below", "below" and "below" the second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0039] It should be noted that if an element is referred to as being "fixed to" or "disposed on" another element, it may be directly on the other element or there may be a central element. If an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. If any, the terms "vertical", "horizontal", "upper", "lower", "left", "right" and similar expressions used in this application are for illustrative purposes only and do not represent the only implementation method.

[0040] See also Figure 1 and Figure 2 , a microplastic mass flux sampling device provided by an embodiment of the present application, the sampler 10 includes a water inlet unit 100, a filter unit, a replacement mechanism 300 and a collection mechanism 400. The filter unit includes a filter screen cover 200, one end of the filter screen cover 200 is open and the other end is closed, the open end of the filter screen cover 200 is connected to the water inlet unit 100, the water inlet unit 100 is used to suck water into the filter screen cover 200, and the filter screen cover 200 is used to retain microplastics in the filtered water. The replacement mechanism 300 is arranged on the side of the filter screen cover 200 close to the water inlet unit 100, and is used to provide the filter screen cover 200 in an unused state, so that the filter screen cover 200 in an unused state is connected to the water inlet unit 100. The collection mechanism 400 is connected to the closed end of the filter screen cover 200, and is used to collect the filter screen cover 200 in a saturated state.

[0041] The water inlet unit 100 includes a water pump 110 and a water inlet pipe 120 connected to the water pump 110, and one end of the filter screen cover 200 is sealed and connected to the water inlet pipe 120. A water inlet grille 130 is provided at the inlet end of the water inlet unit 100, and a check valve is provided in the water inlet pipe 120 to prevent water from flowing back. The filter screen cover 200 is an annular cover body, one end of which is open for connection with the water inlet unit 100, and the other end is closed to intercept microplastics.

[0042] In actual use, the sampler can be placed in a river, and the water inlet unit 100 is used to pump the water pump 110 into the filter screen cover 200, so that the microplastics in the water are retained in the filter screen cover 200, and the filtered water is directly discharged from the mesh of the filter screen cover 200, thereby realizing real-time and continuous sampling of microplastics. The open end of the filter screen cover 200 is connected to the replacement mechanism 300, and the closed end of the filter screen cover 200 is connected to the collection mechanism 400. When the filter screen cover 200 is used for a long time, microplastics are easy to block the mesh of the filter screen cover 200, making it difficult to discharge water. At this time, the filter screen cover 200 is a saturated filter screen cover 200, and the filter screen cover 200 needs to be replaced. When replacing, the collection mechanism 400 can collect the filter screen cover 200 in a saturated state, and the filter screen cover 200 in an unused state is provided through the replacement mechanism 300, thereby realizing the direct replacement of the filter screen cover 200, further improving the sustainable use of the microplastic sampling device. That is, the microplastic sampling device of the present application can achieve continuous sampling in rivers and improve the accuracy of sampling.

[0043] In some embodiments, the unused filter screen cover 200 and the saturated filter screen cover 200 are respectively connected to a portion of the filter screen cover 200, and the unused filter screen cover 200 and the saturated filter screen cover 200 are respectively located at both ends of the filter screen cover 200. The replacement mechanism 300 includes a filter screen box, which is sleeved outside the water outlet of the water inlet unit 100, and the unused filter screen cover 200 is located in the filter screen box. The filter screen box is provided with a filter screen cover outlet 310 at one end close to the collection mechanism 400, and the saturated filter screen cover 200 is used to be wound on the collection mechanism 400.

[0044] It should be noted that when the mesh holes on the filter screen 200 are blocked by microplastics so that the pressure inside the screen is more than three times the pressure outside the screen, the filter screen 200 is regarded as a filter screen 200 in a saturated state.

[0045] In this embodiment, the filter screen cover 200 can be divided into a filter screen cover 200 section in an unused state, a filter screen cover 200 section in a used state, and a filter screen cover 200 section in a saturated state, which are connected in sequence. The filter screen cover 200 in an unused state is located in the filter screen box, and the filter screen cover 200 in a saturated state is used to be wound on the collection mechanism 400. When the filter screen cover 200 in the used state reaches the saturated state, the collection mechanism 400 is turned on, and the collection mechanism 400 rotates to wind the filter screen cover 200 in the saturated state into the collection mechanism 400, and at the same time pulls the filter screen cover 200 in the unused state to the water outlet of the water inlet unit 100, so as to continuously sample microplastics.

[0046] In some other embodiments, the unused filter screen cover 200 and the saturated filter screen cover 200 are two types of filter screen covers 200. A plurality of filter screen covers 200 are arranged in the filter screen box. When the unused filter screen cover 200 becomes the saturated filter screen cover 200 after use, the collection mechanism 400 collects the filter screen cover 200, and the filter screen box provides a new filter screen cover 200.

[0047] In some embodiments, the collection mechanism includes a winding shaft, which can be started, stopped, and operated at will through a control module or 5G remote control. The filter cover in a saturated state is pulled out of the filter box, passes through the bracket 700, and is then wound and collected by the winding shaft.

[0048] In some embodiments, the filter screen cover outlet 310 is an annular structure. In actual use, the long cylindrical filter screen covers 200 with pore sizes of 25 μm and 64 μm can be folded and placed in the filter screen box. The filter screen cover outlet 310 is provided with a rubber sealing ring, and the filter screen cover 200 can be pulled out of the rubber sealing ring.

[0049] Further, a fastening mechanism is provided in the filter box to realize the clamping of the filter cover 200 to prevent the filter cover 200 from being pulled out at will. Alternatively, the filter cover outlet 310 can be closed, and after closing, the filter cover 200 cannot be pulled out from the filter cover outlet 310.

[0050] In some embodiments, the sampler includes a bracket 700 , one end of the bracket 700 is connected to the water inlet unit 100 or the replacement mechanism 300 , and the other end is connected to the collection mechanism 400 . The bracket 700 is used to support the filter screen cover 200 .

[0051] In this embodiment, the bracket 700 includes a frame and a center rod disposed in the frame, the frame is located outside the filter screen cover 200, and the center rod is disposed along the length direction of the filter screen cover 200 and is located inside the filter screen cover 200. The diameter of the filter screen cover 200 is smaller than the bracket 700. The frame is used to support and protect the filter screen cover 200 externally, and the center rod is used to support the filter screen cover 200 internally to prevent the side walls of the filter screen cover 200 from being bonded together.

[0052] In some embodiments, the collection mechanism 400 includes a strapping machine 500 , which is disposed at an exit position of the replacement mechanism 300 and outside the filter screen cover 200 .

[0053] Specifically, the strapping machine 500 is disposed between the filter screen box and the bracket 700 . When sampling is completed, the strapping machine 500 is used to tighten the open end of the filter screen cover 200 from outside the filter screen cover 200 , so as to retain the microplastic sample in the closed filter screen cover 200 .

[0054] In some embodiments, the microplastic sampling device includes a first pressure sensor 600 and a second pressure sensor 800. The first pressure sensor 600 is located outside the sampler and is used to detect the water depth of the sampler. The water depth measurement accuracy is not less than 0.2m. The second pressure sensor 800 is located inside the filter screen cover 200 and is used to detect the pressure inside the filter screen cover 200. The first pressure sensor 600 and the second pressure sensor 800 are connected to the hull through a cable, and the water pressure signals detected by the first pressure sensor 600 and the second pressure sensor 800 are transmitted to the unmanned ship through the signal line in the cable.

[0055] Specifically, the second pressure sensor 800 can be fixed on the central rod of the bracket 700 , or connected to the water inlet pipe 120 .

[0056] In some embodiments, the microplastic sampling device also includes a hull 20 and a line-retracting and -releasing mechanism 40 disposed on the hull 20 , a cable 30 is wound around the line-retracting and -releasing mechanism 40 , and the sampler is connected to the hull 20 via the cable 30 .

[0057] The hull 20 may be an unmanned boat, on which a velocity meter 60 is provided, which is used to measure the water velocity, wherein the velocity meter 60 may be an acoustic Doppler current profiler (ADCP), which can measure the velocity of the river cross section in different regions, with a resolution of no more than 1m and an error rate of no more than 10%; at the same time, the riverbed contour at the river cross section can be mapped, with a resolution of no more than 1m. When the unmanned boat is not sampling, it can be docked in the cabin on the shore, which can reduce manual operation and save the work of transporting the unmanned boat to the site every time sampling is performed. A control module is provided in the cabin, and the unmanned boat and the sampler are started by the control module.

[0058] The retractable cable mechanism 40 includes a winch and a motor. The cable is wound around the winch. The starter is used to drive the winch to rotate to achieve the retractable cable. The sampler is suspended on the unmanned boat through the cable, and the sampler can be lowered to any depth through the retractable cable mechanism 40. The length of the cable is greater than the water depth of the river to be measured. The cable includes a load-bearing line, a signal line and a power line. The water pump is powered by the power line in the cable and controlled by the signal line, which can be controlled by the control module.

[0059] Specifically, the unmanned boat can withstand water flow rates of more than 6 kilometers per hour and can carry more than 5kg of counterweight. The unmanned boat is equipped with an antenna, which can travel along any route in the river through a control module or 5G remote control, and can hover at any position. The unmanned boat is equipped with a cabin fixed to the shore. When the unmanned boat is not working, it docks in the cabin, which can charge the unmanned boat; the cabin is equipped with surveillance cameras and loudspeakers. The unmanned boat control system accesses the river navigation information.

[0060] This application uses an unmanned boat to drive the sampler to move, and the unmanned boat can cruise in a programmed automated or 5G remote control manner. It can travel along any route and speed, and can hover at any position. Traveling means going to the location where sampling is required, and hovering means sampling. In this way, sampling at different horizontal positions in the river section can be achieved, which can solve the problem of uneven distribution of microplastics at different horizontal positions in the river section. It can reduce manual operations and improve detection efficiency and accuracy.

[0061] See also Figure 3 An embodiment of the present application provides a microplastic sampling method, wherein a sampler is connected to a hull 20 via a cable 30, and the sampling method comprises the following steps:

[0062] S1. Select the target section of the river and divide the target section into i layers along the depth direction, where i is a positive integer;

[0063] S2, driving the boat 20 to the first side bank 210 of the target section of the river, lowering the sampler to the first layer target depth 230 through the cable 30, and turning on the sampler, and moving the sampler from the first side bank 210 to the second side bank 220 along the target section through the boat 20;

[0064] S3, lowering the sampler to the target depth of layer 2 by means of the cable 30, and moving the sampler from the second bank 220 of the river to the first bank 210 along the target section by means of the hull 20;

[0065] S4, lowering the sampler to the target depth of layer 3 by means of the cable 30, and moving the sampler from the first bank 210 of the river to the second bank 220 along the target section by means of the hull 20;

[0066] S5. Repeat steps S3 and S4, and increase the number of target depth layers in sequence, until the acquisition of the i-th target depth of 250 is completed.

[0067] In this embodiment, taking the example of dividing the river into four layers along the depth direction, when sampling, first select any section of the river, and then lower the sampler to the first target depth 230 in the river through the cable 30, wherein the first target depth 230 is 0.1m above the water surface, and then drive the sampler from the first side bank 210 of the river to the second side bank 220 through the hull 20; then lower the sampler to the second target depth 240 through the cable 30, and drive the sampler from the second side bank 220 of the river to the first side bank 210 through the hull 20; continue to lower the sampler to the third target depth through the cable 30, and drive the sampler from the first side bank 210 of the river to the second side bank 220 through the hull 20; then lower the sampler to the fourth target depth through the cable 30, and drive the sampler from the second side bank 220 of the river to the first side bank 210 through the hull 20. The depths of the first target depth 230, the second target depth 240, the third target depth and the fourth target depth increase in sequence. Specifically, the distance between two adjacent target depths is a fixed value, which is convenient for increasing the uniformity of the sampling results. For example, the distance between two adjacent target depths is 1m. The sampling route of the sampler is S-shaped, which can ensure continuous and non-repetitive sampling of the sampler and increase the uniformity of the sampling results.

[0068] Dividing the target section into i layers along the depth direction and sampling in each layer separately by the sampler can solve the problem of uneven distribution of microplastics at different depths in the river.

[0069] It should be noted that the total number of target depths is related to the depth of the river and the distance between two adjacent target depths, and can be changed according to actual conditions.

[0070] In some embodiments, the microplastic sampling device includes a strapping machine 500. After each layer of sampling at a target depth is completed, the open end of the filter screen cover 200 in a saturated state is tightened by the strapping machine 500, the collecting mechanism 400 collects the filter screen cover 200 in a saturated state, and the replacement mechanism 300 provides the filter screen cover 200 in an unused state.

[0071] In some embodiments, the microplastic sampling device includes at least a first pressure sensor and a second pressure sensor 800, wherein the first pressure sensor is located outside the sampler, and the second pressure sensor 800 is located inside the filter screen cover 200. When the pressure of the second pressure sensor 800 is more than three times the pressure of the first pressure sensor, the hull 20 stops running, the water inlet unit 100 is closed, the collection mechanism 400 collects the saturated filter screen cover 200, the replacement mechanism 300 provides the unused filter screen cover 200, and finally the hull 20 and the water inlet unit 100 are started at the same time.

[0072] When sampling, the staff first remotely checks the navigation information, selects a safe period, and uses surveillance cameras to confirm that no ships are passing. The remote control device then starts sampling. The sampling steps are as follows:

[0073] The control module is started by 5G remote control, and the control module controls the unmanned boat to sail out of the cabin and locate on one side of the shore of the target section;

[0074] The control module controls the rotation of the retractable cable mechanism to adjust the cable length and lower the sampler to 0.1m below the water surface; the water pump in the sampler is started by 5G remote control, and the unmanned boat travels at a speed of 0.1m / s-0.2m / s perpendicular to the water flow. During the driving process, the water pump sucks river water into the sampler at a rate of 5L / min-20L / min. The river water is filtered through the filter cover and returns to the river channel from the gap between the brackets. Solid suspended matter in the river water, including microplastics, that is larger than the filter mesh aperture (25 μm or 64 μm) remains in the mesh;

[0075] After the unmanned boat reaches the other side of the river, it stops and turns off the water pump. After the water pump is turned off, the control module controls the tying machine to start and close the open end of the filter screen cover; the control module controls the rotation of the reel shaft of the collection module to pull the closed part to the reel shaft and stop. In this way, the filter screen cover between the two closed positions is separated into an independent space, and the collected samples are retained in it. Repeating this process can achieve automatic underwater screen replacement. During driving, if the water pressure in the filter screen cover reaches more than 3 times the depth of the sampler (the filter screen is clogged), stop driving in advance and turn off the water pump to change the screen. After changing the screen, continue driving and turn on the water pump to continue sampling. After reaching the other side of the river, stop driving again and turn off the water pump to change the screen;

[0076] After collecting water samples at a depth of 0.1m and changing the net, the control module controls the retractable cable mechanism to rotate to adjust the cable length and lower the sampler to 1m below the water surface. Then repeat the above process, increasing by 1m each time, and perform scanning sampling layer by layer until the riverbed is reached, completing scanning sampling of the entire river section;

[0077] The unmanned boat starts the ADCP and cruises back and forth along the surface of the river section to measure the flow velocity of each layer of the river. Alternatively, when sampling at different target water depths, the ADCP can be started at the same time to measure the flow velocity of each layer of the river.

[0078] The filter net wrapped around the reel was brought back to the laboratory for sample processing and analysis to obtain the mass concentration of microplastics in the river (g / L). Combined with the flow velocity in each layer, the mass flux of microplastics in the river was calculated using the formula: mass flux = mass concentration × water flow velocity.

[0079] An embodiment of the present application provides a method for monitoring microplastic mass flux, comprising the following steps:

[0080] The river was sampled using microplastic sampling equipment and in accordance with the microplastic sampling method to obtain microplastic samples at each target depth;

[0081] By formula Calculate the mass of plastic per unit volume of water sample at each target depth, where m i is the mass of the i-th plastic particle in a layer of water sample, and v is the volume of the water sample;

[0082] By formula Calculate the plastic mass flux of the target section, where K is the plastic mass flux of the section, MV is the product of the plastic mass per unit volume of water in a layer of water sample and the average flow velocity of the corresponding layer of water, surface is the river surface, and bed is the riverbed.

[0083] In this embodiment, a two-dimensional coordinate system is established with water depth as the horizontal coordinate, and the product of the plastic mass per unit volume of water in each layer of water sample and the average flow velocity of the corresponding layer of water as the vertical coordinate. The adjacent sampling points are connected by straight lines to obtain a curve F(MV). The area of ​​the area enclosed by the curve and the water depth axis can be calculated to obtain the instantaneous mass flux of plastic in the section. A two-dimensional coordinate system is established with time as the horizontal coordinate, and the number of plastic particles passing through the section per unit time and the plastic mass flux are used as the vertical coordinate. The adjacent sampling points are connected by straight lines to obtain a curve F(K). The area of ​​the area enclosed by the curve and the time axis can be calculated to obtain the total number and mass of plastic passing through each hydrological period or the whole year.

[0084] By continuously sampling the S-shaped path at the same section of the water flow to be tested, the sampling accuracy is high. The plastic mass flux is calculated by the product of the plastic mass per unit volume of the water sample and the average flow rate. Compared with the method of determining the number of microplastics in the water flow to be tested in the related art, the present application includes the volume size of microplastic particles in the calculation range, which can more accurately reflect the degree of microplastic pollution in the water flow to be tested.

[0085] In some embodiments, the specific steps of determining the mass of the microplastic sample include:

[0086] Conduct microscopic examination of individual microplastic particles in the sample and measure the volume of each microplastic particle;

[0087] Determine the polymer type of the sample and multiply the density and volume of different types of polymers to obtain the mass of each microplastic particle;

[0088] Add up all the microplastic particles in the samples at the same sampling point to get the total mass of the samples at the corresponding sampling point.

[0089] Specifically, the filter screen after sampling is brought back to the laboratory and backwashed with pure water into a glass sample bottle. Then, according to the microplastic water sample treatment method, the plastic is extracted onto the filter membrane through the process of digestion → flotation → filtration. The samples are examined under a stereo microscope, and the color and shape of each plastic particle (film, fragments, pieces, fibers, microbeads, etc.) are recorded. After measuring its size and calculating the volume of a single plastic particle, Raman spectroscopy is used to determine the polymer type of the sample. The density of different types of polymers is combined and multiplied by the volume to obtain the plastic mass. For larger plastic particles, an ultra-microbalance is used for direct weighing.

[0090] In some embodiments, the sampling period is set according to the flow of the water flow to be measured in different hydrological periods, and the sampling period is positively correlated with the flow of the water flow to be measured in different hydrological periods. For example, the hydrological period, normal water period and dry season of each river are sampled once a month; the sampling is intensified during the flood season, once a week; and the sampling is intensified during the first flood peak of each year, once a day.

[0091] In some embodiments, the total plastic mass of the whole year can be obtained by integrating the plastic mass flux of each hydrological period throughout the year. The specific calculation formula is: Among them, Kphase is the total mass of plastic passing through each hydrological period, Kyear is the total mass of plastic passing through throughout the year, F(K) is the time change curve obtained by connecting the mass of plastic passing through adjacent samples, start is the starting point of the hydrological period or the whole year, and end is the end point of the hydrological period or the whole year.

[0092] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0093] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be construed as limiting the scope of the patent application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent application shall be subject to the attached claims.

Claims

1. A microplastic sampling device, characterized in that: The microplastic sampling device comprises a sampler, and the sampler comprises: Water inlet unit; A filter unit, comprising a filter screen, one end of the filter screen is open and the other end is closed, the open end of the filter screen is connected to the water inlet unit, the water inlet unit is used to suck water into the filter screen, and the filter screen is used to intercept microplastics in the water; a replacement mechanism, disposed on a side of the filter screen cover close to the water inlet unit, for providing the filter screen cover in an unused state, so that the filter screen cover in an unused state is connected to the water inlet unit; and A collecting mechanism connected to the closed end of the filter screen cover and used to collect the filter screen cover in a saturated state; Wherein, the filter screen cover in an unused state and the filter screen cover in a saturated state are respectively a part of the filter screen cover, and the filter screen cover in an unused state and the filter screen cover in a saturated state are respectively located at two ends of the filter screen cover; The replacement mechanism includes a filter box, which is mounted outside the water outlet of the water inlet unit. The unused filter cover is located in the filter box. A filter cover outlet is provided at one end of the filter box close to the collecting mechanism, and the saturated filter cover is wound around the collecting mechanism.

2. The microplastic sampling device according to claim 1, characterized in that: The sampler comprises a bracket, one end of which is connected to the water inlet unit or the replacement mechanism, and the other end of which is connected to the collection mechanism, and the bracket is used to support the filter screen cover.

3. The microplastic sampling device according to claim 1, characterized in that: The collecting mechanism comprises a bundling machine, which is arranged at the exit position of the replacing mechanism and outside the filter screen cover.

4. The microplastic sampling device according to claim 1, characterized in that: The microplastic sampling equipment includes at least a first pressure sensor and a second pressure sensor. The first pressure sensor is located outside the sampler and is used to detect the water depth of the sampler. The second pressure sensor is located inside the filter screen and is used to detect the pressure inside the filter screen.

5. The microplastic sampling device according to claim 1, characterized in that: The microplastic sampling device also includes a hull and a line-retracting and -releasing mechanism arranged on the hull, a cable is wound around the line-retracting and -releasing mechanism, and the sampler is connected to the hull via the cable.

6. A method for sampling microplastics using the microplastic sampling device according to any one of claims 1 to 5, characterized in that: The sampler is connected to the hull via a cable, and the sampling method comprises the following steps: S1. Select the target section of the river and divide the target section into i layers along the depth direction, where i is a positive integer; S2, driving the boat to the first side bank of the target section of the river, lowering the sampler to the first target depth through the cable, and turning on the sampler, and moving the sampler from the first side bank of the river to the second side bank along the target section through the boat; S3, lowering the sampler to the target depth of layer 2 by using the cable, and driving the sampler along the target section from the second side bank of the river to the first side bank by using the hull; S4, lowering the sampler to the target depth of layer 3 by using the cable, and driving the sampler from the first bank of the river to the second bank along the target section by using the hull; S5. Repeat steps S3 and S4, and increase the number of target depth layers in sequence, until the acquisition of the i-th target depth layer is completed.

7. The microplastic sampling method according to claim 6, characterized in that: The microplastic sampling equipment includes a bundling machine. After each layer of sampling at the target depth is completed, the open end of the filter mesh cover in a saturated state is tied tightly by the bundling mechanism, the collecting mechanism collects the filter mesh cover in a saturated state, and the replacement mechanism provides an unused filter mesh cover.

8. The microplastic sampling method according to claim 6, characterized in that: The microplastic sampling device comprises at least a first pressure sensor and a second pressure sensor, wherein the first pressure sensor is located outside the sampler and the second pressure sensor is located inside the filter screen; When the pressure of the second pressure sensor is greater than or equal to 3 times the pressure of the first pressure sensor, the hull stops running, the water inlet unit is closed, the collecting mechanism collects the saturated filter mesh cover, the replacement mechanism provides the unused filter mesh cover, and then the hull and the water inlet unit are started simultaneously.

9. A method for monitoring microplastic mass flux, characterized in that: The steps include: Sampling the river by the microplastic sampling method described in any one of claims 6 to 8 to obtain microplastic samples at each target depth; By formula Calculate the mass of plastic per unit volume of water sample at each target depth, where m i is the mass of the i-th plastic particle in a layer of water sample, and v is the volume of the water sample; By formula Calculate the plastic mass flux of the target section, where K is the plastic mass flux of the section, MV is the product of the plastic mass per unit volume of water in a layer of water sample and the average flow velocity of the corresponding layer of water, surface is the river surface, and bed is the riverbed.

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