Device for measuring the amount of microplastics settling and resuspension in shallow lakes and its application

Abstract

The present invention relates to the measurement of microplastics in lakes, and in particular to a device for measuring the sedimentation and resuspension of microplastics in shallow lakes and its application. The device comprises a bracket, a first frame, a second frame, a water microplastics trap and an atmospheric microplastics trap; the bracket comprises a vertical rod and a first support and a second support arranged on the upper part of the vertical rod; the first support is located below the second support; the first frame is suspended on the first support; the water microplastics trap is an open-top container, which is fixed in the first frame; the second frame is fixed on the second support; the atmospheric microplastics trap is an open-top container, which is fixed in the second frame. The device has a simple structure and is easy to operate, and can simultaneously obtain the total sedimentation of microplastics in lakes, the atmospheric sedimentation of microplastics and the resuspension of microplastics.

Description

Technical Field

[0001] The invention relates to lake microplastic measurement, and in particular to a device for measuring the sedimentation and resuspension amount of microplastics in shallow lakes and applications thereof. Background Art

[0002] Microplastics refer to plastic particles smaller than 5 mm in the environment. The density of most microplastics is between 0.8 and 1.4 kg / m 3 range. Due to its many uses and wide sources, it is widely distributed in surface water environments such as lakes, reservoirs and rivers, and is a new type of pollutant that has attracted much attention in recent years. Generally speaking, microplastics with higher density will be enriched in sediments under the action of gravity after entering the water system. However, due to their relatively low mass, microplastics in sediments are easily disturbed by hydrodynamic forces and returned to the overlying water body, causing secondary pollution. Especially in shallow lakes, the sedimentary materials at the bottom are easily resuspended due to wind and waves. Therefore, sedimentation-resuspension is the main migration process of microplastics in shallow lakes. At present, there are few studies on the migration process of microplastics in shallow lakes, especially the lack of equipment to accurately quantify the sedimentation-resuspension process of microplastics in lakes. Summary of the invention

[0003] In order to quantify the sedimentation-resuspended process of microplastics in shallow lakes, a microplastic sedimentation-resuspended measuring device was invented. The device has a simple structure and is easy to operate. It can simultaneously obtain the atmospheric sedimentation of microplastics, the total sedimentation of microplastics in lakes, and the resuspended amount of microplastics.

[0004] On the one hand, the present invention provides a device for measuring the sedimentation and resuspension of microplastics in shallow lakes, characterized in that it comprises a bracket, a first frame 1, a second frame 2, a water microplastics capturer 3 and an atmospheric microplastics capturer 4;

[0005] The bracket includes a vertical rod 5 for inserting into the bottom mud, and a first support member 6 and a second support member 7 arranged on the upper part of the vertical rod 5; the first support member 6 is located below the second support member 7;

[0006] The first frame 1 is suspended on the first support member 6; the water body microplastic capture device 3 is an open-top container, which is fixed in the first frame 1;

[0007] The second frame 2 is fixed on the second support member 7; the atmospheric microplastics capturer 4 is an open-top container, which is fixed in the second frame 2;

[0008] During measurement, the first frame 1 and the water microplastic capturer 3 therein are completely immersed in water; the second frame 2 and the atmospheric microplastic capturer 4 therein are located above the water surface; the top openings of the water microplastic capturer 3 and the atmospheric microplastic capturer 4 are kept horizontal.

[0009] The device for measuring the sedimentation and resuspension of microplastics in shallow lakes provided by the present invention can simultaneously measure the total sedimentation and resuspension of microplastics in shallow lakes through a simple and ingenious structural design. The total sedimentation of microplastics in lakes includes three parts, namely, the resuspension of microplastics, the aggregation sedimentation of microplastics, and the atmospheric sedimentation of microplastics (e.g. Figure 1 As shown). Among them, the total amount of microplastics deposited in the lake can be directly obtained by measuring the amount of microplastics collected in the water microplastics trap, the amount of microplastics deposited in the atmosphere can be directly obtained by measuring the amount of microplastics collected in the atmospheric microplastics trap, and the amount of microplastics aggregated and deposited can be calculated based on the concentration of suspended particles in the lake, flow rate and other parameters. For example, the calculation of microplastics aggregated and deposited (flux) can refer to the method described in the document "Ellen Besseling, Joris TKQuik, Muzhi Sun, et al. Fate of nano-and microplastic in freshwater systems: A modeling study [J]. Environmentpollution. 2017, 220 (01): 540-548". Therefore, the amount of microplastics re-suspended can be obtained by subtracting the amount of microplastics atmospheric deposition and microplastics aggregated and deposited from the total amount of microplastics deposited in the lake.

[0010] In the device of the present invention, the first frame is used to carry, accommodate and / or fix the water microplastic capturer, so that the water microplastic capturer remains vertical and the top opening of the water microplastic capturer remains horizontal. The device may include one or more first frames, and one or more water microplastic capturers may be fixed in the first frame. The first frame is a frame-type container made of frame bars by welding or other suitable connection methods. The frame bars at the bottom are arranged to support the water microplastic capturer, and the frame bars on the side are arranged to enclose the water microplastic capturer. The top may have no frame bars (open) or may have frame bars. The top frame bars preferably do not block the top opening of the water microplastic capturer. The size of the first frame can be determined according to the size of the water microplastic capturer and the number of water microplastic capturers that need to be accommodated. After the water microplastic capturer is loaded into the first frame, the water microplastic capturer is fixed to the frame bars of the first frame by suitable fixings (such as a tight hoop or a strap) to prevent the water microplastic capturer from shaking or tilting. The first frame is suspended on the first support member by a suitable suspension component (such as a stainless steel rope), and the depth at which the water body microplastic trap sinks into the water body can be adjusted by adjusting the length of the suspension component (such as a stainless steel rope).

[0011] In the device of the present invention, the second frame is used to carry, accommodate and / or fix the atmospheric microplastic capturer, so that the atmospheric microplastic capturer remains vertical and the top opening of the atmospheric microplastic capturer remains horizontal. The device may include one or more second frames, and one or more atmospheric microplastic capturers may be fixed in the second frame. The second frame is a frame-type container made of frame bars by welding or other suitable connection methods. The frame bars at the bottom are arranged to support the atmospheric microplastic capturer, and the frame bars on the sides are arranged to enclose the atmospheric microplastic capturer. The top may be without frame bars (open) or with frame bars. The top frame bars preferably do not block the top opening of the atmospheric microplastic capturer. The size of the second frame can be determined according to the size of the atmospheric microplastic capturer and the number of atmospheric microplastic capturers that need to be accommodated. The size of the second frame can be larger than that of the atmospheric microplastics trap. After the atmospheric microplastics trap is loaded into the second frame, the atmospheric microplastics trap is fixed to the frame bar of the second frame by suitable fixings (such as a tight hoop or a strap) to prevent the atmospheric microplastics trap from shaking or tilting. The size of the second frame can also exactly match the size of the atmospheric microplastics trap, so that after the atmospheric microplastics trap is placed in the second frame, it can always remain upright even without using fixings, thereby keeping the top opening horizontal. The second frame is fixed to the second support member by fixings (such as bolts and nuts).

[0012] In some embodiments of the present invention, the installation and use methods of the device are as follows: first, fix the first support member and the second support member on the upper part of the vertical rod, and then insert the bottom end of the vertical rod into the bottom mud of the lake, so that the assembled bracket is stably erected in the water area of ​​the lake to be tested, at this time, the first support member is located above the water surface, on the water surface, or under the water surface for easy operation, and the second support member is located above the water surface. During the fixing process of the bracket, it is possible to disturb the microplastics in the lake bottom mud, causing the microplastics to re-suspend and affect the test accuracy. In order to ensure the accuracy of the measurement, after the bracket is fixed for 24 hours, the water body microplastic capturer and the atmospheric microplastic capturer are installed on the bracket. The installation method of the water body microplastic capturer is: fix the water body microplastic capturer in the first frame, and then hang the first frame on the first support member by a stainless steel rope; slowly sink the first frame and the water body microplastic capturer inside it completely into the water and set it at a predetermined water body depth, so that the top opening of the water body microplastic capturer remains horizontal. The installation method of the atmospheric microplastics trap is as follows: fix the atmospheric microplastics trap in the second frame, and then fix the second frame on the second support member so that the top opening of the atmospheric microplastics trap remains horizontal. Start collecting, the microplastics in the water body naturally fall into the water body microplastics trap, and the microplastics in the atmosphere naturally fall into the atmospheric microplastics trap. After collecting for a period of time, the water body microplastics trap and the atmospheric microplastics trap are retrieved in sequence or all at once as needed, and the amount of microplastics collected in the water body microplastics trap and the atmospheric microplastics trap is measured respectively. The amount of microplastics collected in the water body microplastics trap is the total sedimentation of microplastics in the lake; the amount of microplastics collected in the atmospheric microplastics trap is the atmospheric sedimentation of microplastics; the total sedimentation of microplastics in the lake minus the atmospheric sedimentation of microplastics and then minus the aggregated sedimentation of microplastics in the lake is the re-suspension amount of microplastics in the lake.

[0013] In some embodiments of the present invention, the first support member 6 is a first cross bar vertically fixed to the vertical bar 5; the first frame 1 is suspended at both ends of the first cross bar. The first cross bar can be in the shape of a sheet, a stick, a rod or other suitable shapes. The first cross bar and the vertical bar are welded or detachably connected (for example, connected by a right-angle fastener). The distance between the far end of the first cross bar (the end away from the vertical bar) and the vertical bar can ensure that after the first frame is hung on the first cross bar, the first frame and the water microplastic capture device inside it remain vertical, and the top opening of the water microplastic capture device remains horizontal.

[0014] In some embodiments of the present invention, the second support member 7 is a second crossbar vertically fixed to the vertical rod 5. The second crossbar can be in a sheet, rod or other suitable shape. The second crossbar is welded or detachably connected to the vertical rod (for example, connected by a right-angle fastener).

[0015] In some embodiments of the present invention, trays are fixedly provided at both ends of the second crossbar, and the bottom of the second frame 2 is fixed on the trays. The bottom of the second frame is fixed to the tray by bolts and nuts or other suitable means. The tray is preferably made of stainless steel. The size of the tray is greater than, equal to or less than the size of the bottom of the second frame, whichever is greater, equal to or smaller than the size of the bottom of the second frame, so as to stably support the second frame.

[0016] In some embodiments of the present invention, the top opening of the water microplastic trap 3 is covered with a filter 8 with a pore size of 5-10 mm. The filter can effectively prevent large zooplankton in the water from entering the water microplastic trap and affecting the test accuracy, and does not affect the free entry of microplastics in the water into the water microplastic trap.

[0017] The atmospheric microplastics trap and the water microplastics trap can be made of ordinary glass, or other suitable materials, such as stainless steel. The atmospheric microplastics trap and the water microplastics trap can be cylinders with an open top, or other suitable shapes with an open top, such as a cuboid or a cube. In some embodiments of the present invention, the water microplastics trap 3 and / or the atmospheric microplastics trap 4 are cylindrical glass bottles.

[0018] In the device of the present invention, all components must be made of non-plastic materials. In some embodiments of the present invention, the first frame 1, the second frame 2, the vertical rod 5, the first support member 6, the second support member 7 and / or the filter screen 8 are made of stainless steel.

[0019] In some embodiments of the present invention, a weight 9 is hung at the bottom of the first frame 1 to keep the top opening of the water microplastic trap 3 horizontal in the water. The weight can further stabilize the first frame, so that the first frame and the water microplastic trap inside it are in a vertical state, thereby keeping the top opening of the water microplastic trap horizontal.

[0020] In some embodiments of the present invention, the vertical rod 5 has a sharp bottom end, which is conducive to the vertical rod being inserted into the bottom mud of the lake to be tested.

[0021] In some embodiments of the present invention, stainless steel hoops are provided on the first frame 1 and the second frame 2, respectively, and the water microplastics trap 3 and the atmosphere microplastics trap 4 are fixed in the first frame 1 and the second frame 2, respectively, by the stainless steel hoops. The diameter of the stainless steel hoop is slightly larger than the diameter of the water microplastics trap or the atmosphere microplastics trap. The stainless steel hoop is put on the upper, middle and / or lower part of the water microplastics trap or the atmosphere microplastics trap, and the side frame strips of the first frame 1 or the second frame 2 are put on at the same time. The stainless steel hoop is tightened by the bolts and nuts on the stainless steel hoop, and the water microplastics trap and the atmosphere microplastics trap are fixed in the first frame 1 and the second frame 2, respectively, so as to keep the traps upright.

[0022] The application of any of the above-mentioned devices in measuring the sedimentation and resuspension amount of microplastics in shallow lakes also falls within the protection scope of the present invention.

[0023] On the other hand, the present invention also provides a method for measuring the sedimentation and resuspension of microplastics in shallow lakes, characterized in that: using any of the above-mentioned devices, the measurement is carried out according to the following method:

[0024] Insert the vertical rod 5 of the bracket vertically downward into the bottom mud of the lake;

[0025] Fix the water microplastics trap 3 in the first frame 1, hang the first frame 1 on the first support 6 with a stainless steel rope, slowly sink the first frame 1 and the water microplastics trap 3 inside it into the water, so that the opening of the water microplastics trap 3 faces upward and remains horizontal; at the same time, fix the atmospheric microplastics trap 4 in the second frame 2, and then fix the second frame 2 on the second support 7, so that the opening of the atmospheric microplastics trap 4 faces upward and remains horizontal;

[0026] The water microplastic capturer 3 and the atmospheric microplastic capturer 4 are retrieved, and the amount of microplastics collected in the two capturers is measured respectively; the amount of microplastics in the water microplastic capturer 3 is the total sedimentation of microplastics in the lake. The total sedimentation is subtracted from the amount of microplastics in the atmospheric microplastic capturer 4 and then subtracted from the aggregation and sedimentation of microplastics in the lake to obtain the re-suspended amount of microplastics in the lake.

[0027] In summary, the device for measuring the sedimentation and resuspension amount of microplastics in shallow lakes of the present invention has the advantages of simple structure, simple production and low cost. It can simultaneously measure the total sedimentation and resuspension amount of microplastics in shallow lakes, and accurately quantify the sedimentation-resuspension process of microplastics in lakes, which is of great significance for understanding the migration law of microplastics in lakes, and is also the key to constructing a microplastic migration model.

[0028] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

[0029] As used in the present invention, the term "microplastic trap" refers to a container with an open top, which can be a cylindrical, rectangular or cube-shaped structure, and is made of materials such as glass or stainless steel. The "microplastic trap" is used to receive microplastics in the environment, such as microplastics in the atmosphere or in water.

[0030] As used in the present invention, the term "frame" refers to a frame-type container made of frame bars by welding or other suitable connection methods, wherein the frame bars at the bottom are arranged to hold the target object, and the frame bars at the side are arranged to surround the target object. The frame bars used to make the "frame" are made of a material with high strength, such as stainless steel. The shape and size of the "frame" are designed according to actual needs.

[0031] As used in the present invention, the term "vertical rod" refers to a rod-shaped component used for longitudinal support. The term "crossbar" refers to a rod-shaped or similarly shaped component arranged transversely relative to the vertical rod. "Horizontal" and "vertical" both refer to the orientation of the device when in use. The "vertical rod" and "crossbar" are made of high-strength materials (such as stainless steel). BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The following is a schematic diagram of an apparatus in an exemplary embodiment of the present invention, which is only used to explain and illustrate the present invention and is not used to limit the scope of the present invention.

[0033] Figure 1 .Schematic diagram of the migration process of microplastics in shallow lakes; the total amount of microplastics deposited in lakes = the amount of microplastics re-suspended in lakes + the amount of microplastics atmospheric deposited in lakes + the amount of microplastics aggregated and deposited in lakes.

[0034] Figure 2 .Schematic diagram of the structure of a device for measuring the sedimentation and resuspension amount of microplastics in shallow lakes in an exemplary embodiment of the present invention.

[0035] Figure 3 .Schematic diagram of the structure of a device for measuring the sedimentation and resuspension amount of microplastics in shallow lakes in another exemplary embodiment of the present invention.

[0036] Figure 4 .Schematic diagram of a water microplastic trap in an exemplary embodiment of the present invention (showing a filter).

[0037] Figure numerals: 1-first frame, 2-second frame, 3-water microplastic trap, 4-atmospheric microplastic trap, 5-vertical rod, 6-first support member, 7-second support member, 8-filter screen, 9-weight. DETAILED DESCRIPTION

[0038] The present invention will be further described below in conjunction with the accompanying drawings.

[0039] like Figure 2 As shown, the present invention provides a device for measuring the sedimentation and resuspension of microplastics in shallow lakes, characterized in that it includes a bracket, a first frame 1, a second frame 2, a water microplastic capturer 3 and an atmospheric microplastic capturer 4; the bracket includes a vertical rod 5 for inserting into the bottom mud and a first support member 6 and a second support member 7 arranged on the upper part of the vertical rod 5; the first support member 6 is located below the second support member 7; the first frame 1 is suspended on the first support member 6; the water microplastic capturer 3 is a top-open container, which is fixed in the first frame 1; the second frame 2 is fixed on the second support member 7; the atmospheric microplastic capturer 4 is a top-open container, which is fixed in the second frame 2; during measurement, the first frame 1 and the water microplastic capturer 3 therein are completely immersed in water; the second frame 2 and the atmospheric microplastic capturer 4 therein are located above the water surface; the top openings of the water microplastic capturer 3 and the atmospheric microplastic capturer 4 are kept horizontal.

[0040] In some embodiments, the first support member 6 is a first crossbar vertically fixed to the vertical rod 5; the first frame 1 is suspended at both ends of the first crossbar. In some embodiments, the first crossbar is perpendicular to the vertical rod 5 and welded to the vertical rod 5. In other embodiments, the first crossbar is vertically fixed to the vertical rod 5 by a fixing member. In some embodiments, the fixing member is a right-angle fastener.

[0041] In some other embodiments, the first support member 6 is a hanging ring or a hook. In other embodiments, the first support member 6 is other parts suitable for hanging objects, and the shape is not limited.

[0042] In some embodiments, the second support member 7 is a second cross bar vertically fixed to the vertical bar 5. In some embodiments, the second cross bar is perpendicular to the vertical bar 5 and welded to the vertical bar 5. In other embodiments, the second cross bar is vertically fixed to the vertical bar 5 by a fixing member. In some embodiments, the fixing member is a right-angle fastener.

[0043] In some embodiments, two upper and lower second cross bars are fixed to the vertical bar 5; the frame bar on the upper side of the second frame 2 is fixed to the upper second cross bar, and the frame bar on the lower side is fixed to the lower second cross bar, thereby fixing the second frame 2. In some embodiments, the frame bar of the second frame 2 is fixed to the second cross bar by bolts and nuts.

[0044] In some embodiments, trays are fixedly provided at both ends of the second crossbar, and the bottom of the second frame 2 is fixed on the trays. In some embodiments, the second frame 2 is fixed to the trays by bolts and nuts. In some embodiments, the trays are made of stainless steel. In some embodiments, the trays are welded to the second crossbar.

[0045] In some embodiments, the top opening of the water microplastic capture device 3 is covered with a filter screen 8 (such as Figure 4 In some embodiments, the pore size of the filter screen 8 is 5-10 mm. In some embodiments, the pore size of the filter screen 8 is 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm.

[0046] In some embodiments, the water microplastics trap 3 and / or the atmospheric microplastics trap 4 are made of glass. In other embodiments, the water microplastics trap 3 and / or the atmospheric microplastics trap 4 are made of stainless steel.

[0047] In some embodiments, the water microplastics trap 3 and / or the atmospheric microplastics trap 4 is a cylinder with an open top. In other embodiments, the water microplastics trap 3 and / or the atmospheric microplastics trap 4 is a rectangular parallelepiped, a cube or other suitable shapes with an open top.

[0048] In some embodiments, the water microplastic capture container 3 and / or the atmospheric microplastic capture container 4 is a cylindrical glass bottle with an open top.

[0049] In some embodiments, the ratio of the height to the diameter of the water microplastic capture device 3 and / or the atmospheric microplastic capture device 4 is 5:1.

[0050] In some embodiments, the first frame 1, the second frame 2, the vertical rod 5, the first support member 6, the second support member 7 and / or the filter screen 8 are made of stainless steel. In some embodiments, the first support member 6 and the second support member 7 are made of iron frames.

[0051] In some embodiments, the first frame 1 and / or the second frame 2 is a stainless steel frame welded from stainless steel bars, and the stainless steel bars at the bottom are arranged to support the water microplastic trap 3 or the atmospheric microplastic trap 4. In some embodiments, the stainless steel frame is a rectangular parallelepiped, and its bottom and top surfaces are square, and its height is greater than the side lengths of the bottom and top surfaces.

[0052] In some embodiments, the height of the water microplastic capturer 3 is greater than the height of the first frame 1. In some embodiments, the height of the atmospheric microplastic capturer 4 is greater than the height of the second frame 2.

[0053] In some embodiments, a weight 9 is suspended at the bottom of the first frame 1 to keep the top opening of the water body microplastic trap 3 horizontal in the water. In some embodiments, the weight of the weight is about 2 kg.

[0054] In some embodiments, the vertical rod 5 has a sharp bottom end.

[0055] In some embodiments, stainless steel hoops are respectively provided on the first frame 1 and the second frame 2, and the water microplastic capturer 3 and the atmospheric microplastic capturer 4 are respectively fixed in the first frame 1 and the second frame 2 through the stainless steel hoops.

[0056] In other embodiments, the water body microplastic capturer 3 and the atmospheric microplastic capturer 4 are fixed in the first frame 1 and the second frame 2 respectively by other fixing components (for example, straps).

[0057] In some embodiments, the device of the present invention includes two first frames 1, one second frame 2, a first support member 6, and a second support member 7; two water microplastic capturers 3 are fixed in each first frame 1, and two atmospheric microplastic capturers 4 are fixed in each second frame 2; the first support member 6 is a first cross bar, and the first frame 1 is suspended at both ends of the first cross bar by stainless steel ropes; the second frame 2 is fixed to the second support member 7 by bolts and nuts.

[0058] In some embodiments, the device of the present invention includes two first frames 1, two second frames 1, a first support member 6 and a second support member 7; two water microplastic capturers 3 are fixed in each first frame 1, and two atmospheric microplastic capturers 4 are fixed in each second frame 2; the first support member 6 is a first cross bar, and the first frame 1 is suspended at both ends of the first cross bar by stainless steel ropes; the second support member 7 is a second cross bar, and the second frame 2 is fixed to both ends of the second cross bar by bolts and nuts.

[0059] The present invention also provides a method for measuring the sedimentation and resuspension of microplastics in shallow lakes, using any of the above-mentioned devices to perform measurements according to the following method:

[0060] Insert the vertical rod 5 of the bracket vertically downward into the bottom mud of the lake;

[0061] Fix the water microplastics trap 3 in the first frame 1, hang the first frame 1 on the first support 6 with a stainless steel rope, slowly sink the first frame 1 and the water microplastics trap 3 inside it into the water, so that the opening of the water microplastics trap 3 faces upward and remains horizontal; at the same time, fix the atmospheric microplastics trap 4 in the second frame 2, and then fix the second frame 2 on the second support 7, so that the opening of the atmospheric microplastics trap 4 faces upward and remains horizontal;

[0062] The water microplastic capturer 3 and the atmospheric microplastic capturer 4 are retrieved, and the amount of microplastics collected in the two capturers is measured respectively; the amount of microplastics in the water microplastic capturer 3 is the total sedimentation of microplastics in the lake. The total sedimentation is subtracted from the amount of microplastics in the atmospheric microplastic capturer 4 and then subtracted from the aggregation and sedimentation of microplastics in the lake to obtain the re-suspended amount of microplastics in the lake.

[0063] In some embodiments of the present invention, the following method is used to make the device of the present invention and measure the amount of microplastic sedimentation and resuspension in shallow lakes:

[0064] Required Materials

[0065] 8 cylindrical glass containers with a diameter-to-height ratio of 1:5 (to meet the design requirements of the capture device), 4 stainless steel frames, stainless steel rods (2-5 meters, determined according to the water depth of the lake), stainless steel ropes, iron frames, etc.

[0066] Preparation method

[0067] 1. Make a bracket: Use a stainless steel rod as a vertical rod, and preferably make the bottom of the vertical rod into a sharp structure so that it is easier to insert into the bottom mud of the lake to be tested. Use an iron frame as a support member, and fix it vertically on the upper part of the vertical rod by welding or by a fixing member (such as a right-angle fastener). The iron frame at the bottom is the first support member, and the iron frame at the top is the second support member.

[0068] 2. Put the cylindrical glass container into the stainless steel frame, use the stainless steel hoop to cover the upper, middle and / or lower part of the cylindrical glass container, and at the same time cover the side frame bars of the stainless steel frame, and then tighten the stainless steel hoop with the bolts and nuts on the stainless steel hoop to firmly fix the cylindrical glass container in the stainless steel frame. Two glass containers are placed in each stainless steel frame, and the bottle mouth of the glass container is kept horizontal. Two of the stainless steel frames are the first frame, and the glass containers in the first frame are used as water microplastics capturers. The other two stainless steel frames are the second frame, and the glass containers in the second frame are used as atmospheric microplastics capturers.

[0069] It is preferred to cover the mouth of the microplastic trap with a stainless steel mesh with a hole diameter of about 1 cm to prevent large zooplankton from entering the trap and affecting the test accuracy. It is preferred to hang a weight of about 2 kg under the first frame to ensure that the first frame can remain horizontal in the water and the microplastic trap can remain vertical. Tie a strong stainless steel rope on the top of the first frame, and adjust the length of the stainless steel rope according to the experimental needs to set the microplastic trap at different depths in the water.

[0070] Experimental methods

[0071] 1. Fix the bracket: Fix the bracket in the lake before the test. The fixing method is: insert the bottom end of the vertical rod vertically downward into the bottom mud of the lake, and the insertion depth is based on the stability of the bracket; after inserting into the bottom mud, keep the vertical rod vertical, and keep the first support and the second support horizontal; the second support is located above the water surface; the first support can be located above the water surface, on the water surface or under the water surface where it is easy to operate, preferably above the water surface.

[0072] 2. Installation: When inserting the vertical rod into the bottom mud, it is easy to disturb the lake sediment and cause the microplastics to re-suspend. To avoid affecting the test accuracy, after 24 hours, the first frame equipped with the water microplastics capture device is hung on both ends of the first support member through a strong stainless steel rope (or stainless steel iron cable), with one first frame hung on one end. Holding the stainless steel rope, slowly sink the first frame and the water microplastics capture device inside it into the water so that the water microplastics capture device is completely immersed in the water. By adjusting the length of the stainless steel rope, the water microplastics capture device is set at the water depth required for the experiment; at the same time, the second frame equipped with the atmospheric microplastics capture device is fixed to the second support member through fixings (bolts and nuts, etc.).

[0073] 3. Collection: Microplastics in the atmosphere fall into the atmospheric microplastics capture device, and microplastics in the water fall into the water microplastics capture device. Set the collection time of microplastics as needed.

[0074] 4. Measurement: Take back the atmospheric microplastic trap and the water microplastic trap in turn or all at once as needed and send them back to the laboratory to detect the abundance of microplastics in the water microplastic trap and the atmospheric microplastic trap respectively, so as to know the total amount of microplastics deposited in the water and the amount of microplastics deposited in the atmosphere, and calculate the amount of microplastics aggregated and deposited in the lake. Then, the amount of microplastics re-suspended in the lake can be obtained by subtracting the amount of microplastics deposited in the atmosphere and the amount of microplastics aggregated and deposited in the lake from the total amount of microplastics deposited in the water. Among them, the abundance of microplastics can be detected by referring to the method described in the literature Su L, Xue YG, Li LY, et al. Microplastics in Taihu Lake, China [J]. Environment Pollution, 2016, 216, 711-719. The amount of microplastic aggregation and sedimentation can be calculated by referring to the method described in the literature "Ellen Besseling, Joris TKQuik, Muzhi Sun, et al. Fate of nano-and microplastic in freshwater systems: A modeling study [J]. Environment pollution. 2017, 220(01): 540-548".

[0075] During the entire experimental process mentioned above, efforts should be made to avoid disturbing the lake bottom sediments, which would cause the microplastics to re-suspension and affect the accuracy of the experiment.

[0076] The words "upper", "lower", "left", "right", "front", "back", etc. used in this article to describe the directions are for the convenience of explanation and are based on the directions shown in the drawings. In actual devices, these directions may be different due to the placement of the device.

[0077] Obviously, the above embodiments of the present invention are merely examples for clearly explaining the present invention, and are not intended to limit the implementation methods of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is impossible to list all the implementation methods here. Any obvious changes or modifications derived from the technical solution of the present invention are still within the protection scope of the present invention.

Claims

1. A device for measuring the sedimentation and resuspension of microplastics in shallow lakes, characterized by: It comprises a bracket, a first frame (1), a second frame (2), a water microplastics trap (3) and an atmospheric microplastics trap (4); The support comprises a vertical rod (5) for inserting into the bottom mud, and a first support member (6) and a second support member (7) arranged on the upper part of the vertical rod (5); the first support member (6) is located below the second support member (7); The first frame (1) is suspended on the first support member (6); the water body microplastic capture device (3) is an open-top container, which is fixed in the first frame (1); The second frame (2) is fixed on the second support member (7); the atmospheric microplastics capture device (4) is an open-top container, which is fixed in the second frame (2); The top opening of the water body microplastic trap (3) is covered with a filter (8) with a pore size of 5-10 mm; The water body microplastics trap (3) and the atmospheric microplastics trap (4) are cylindrical glass bottles; During measurement, the first frame (1) and the water microplastics trap (3) therein are completely immersed in water; the second frame (2) and the atmospheric microplastics trap (4) therein are located above the water surface; and the top openings of the water microplastics trap (3) and the atmospheric microplastics trap (4) are kept horizontal.

2. The device according to claim 1, characterized in that: The first support member (6) is a first cross bar vertically fixed on the vertical rod (5), and the first frame (1) is suspended at both ends of the first cross bar; and / or the second support member (7) is a second cross bar vertically fixed on the vertical rod (5).

3. The device according to claim 2, characterized in that: Trays are fixedly provided at both ends of the second crossbar, and the bottom of the second frame (2) is fixed on the trays.

4. The device according to claim 1, characterized in that: The first frame (1), the second frame (2), the vertical rod (5), the first support member (6), the second support member (7) and / or the filter screen (8) are made of stainless steel material.

5. The device according to claim 1, characterized in that: A weight (9) is hung at the bottom of the first frame (1) to keep the top opening of the water body microplastic trap (3) level in the water; and the vertical rod (5) has a sharp bottom end.

6. The device according to claim 1, characterized in that: The first frame (1) and the second frame (2) are respectively provided with stainless steel hoops, and the water body microplastics capture device (3) and the atmosphere microplastics capture device (4) are respectively fixed in the first frame (1) and the second frame (2) via the stainless steel hoops.

7. Application of the device described in any one of claims 1 to 6 in measuring the amount of microplastic sedimentation and resuspension in shallow lakes.

8. A method for measuring the amount of microplastics settled and resuspended in shallow lakes, characterized in that: Using the device described in any one of claims 1 to 6, the measurement is performed according to the following method: Insert the vertical rod (5) of the support vertically downward into the bottom mud of the lake; The water microplastics trap (3) is fixed in the first frame (1), the first frame (1) is suspended on the first support (6) with a stainless steel rope, and the first frame (1) and the water microplastics trap (3) therein are slowly and completely submerged in water, so that the opening of the water microplastics trap (3) faces upward and remains horizontal; at the same time, the atmosphere microplastics trap (4) is fixed in the second frame (2), and then the second frame (2) is fixed on the second support (7), so that the opening of the atmosphere microplastics trap (4) faces upward and remains horizontal; The water microplastics trap (3) and the atmospheric microplastics trap (4) were retrieved, and the amount of microplastics collected in the two traps was measured respectively; The amount of microplastics in the water microplastics capture device (3) is the total amount of microplastics deposited in the lake. The total amount of microplastics is subtracted from the amount of microplastics in the atmospheric microplastics capture device (4) and then from the amount of microplastics aggregated and deposited in the lake to obtain the amount of microplastics re-suspended in the lake.

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