A simulation method for the dynamic processes of microplastic sedimentation and suspension in a lake water-sediment system

Abstract

This invention relates to the field of aquatic environment technology, and in particular to a method for simulating the dynamic processes of microplastic sedimentation and suspension in a lake water-sediment system. An indoor simulation system is constructed, with sedimentation and suspension simulation tanks continuously fed with water via peristaltic pumps to simulate dynamic water flow. Sediments are introduced into the sedimentation and suspension simulation tanks to simulate the real lake water environment, i.e., the in-situ environment of water and sediments, with different water flow rates input to simulate the real water flow environment. Sediment and overlying water are collected at multiple time periods to analyze the abundance of microplastic particles, thereby obtaining corresponding experimental data. It is evident that this simulation method does not require the on-site installation of corresponding devices, reducing the difficulty of the simulation experiment, saving time and effort, and lowering detection costs. Furthermore, by introducing sediments into each simulation tank to simulate the actual lake water-sediment system, the gap between the simulation experiment and reality is narrowed, improving the accuracy of the obtained experimental data.

Description

Technical Field

[0001] This invention relates to the field of water environment technology, and in particular to a method for simulating the dynamic processes of microplastic sedimentation and suspension in lake water-sediment systems. Background Technology

[0002] The rapid increase in microplastic pollution in aquatic environments has drawn significant attention and presented new challenges to water pollution control, particularly the sedimentation and suspension processes of microplastics in lake water-sediment systems. Microplastics not only migrate and diffuse within water bodies but also settle into sediments, while microplastics in sediments can also be suspended in the water. Furthermore, lake water is not static; the inflow and outflow of microplastics is a dynamic process, making the sedimentation and suspension of microplastics equally dynamic.

[0003] For example, the Chinese invention CN113310859A discloses a device for measuring the sedimentation and resuspension of microplastics in shallow lakes and its application. Before the experiment, the support is fixed in the lake. The fixing method is as follows: the bottom end of the vertical rod is inserted vertically downwards into the lakebed sediment, the insertion depth being sufficient to ensure the stability of the support; after insertion into the sediment, the vertical rod is kept vertical, and the first and second supports are kept horizontal; the second support is located above the water surface; the first support can be located above, above, or below the water surface in an easily accessible position, preferably above the water surface. It is evident that this type of measuring device needs to be deployed in the field for observation (i.e., in-situ observation). Due to the high degree of uncontrollability associated with in-situ observation, the observation is difficult to conduct, time-consuming, labor-intensive, and costly.

[0004] In addition, the indoor simulation device for measuring the movement rate of microplastics in water, as disclosed in Chinese invention CN111896437A, although the device can detect different movement states of microplastics, including settling rate, initial movement rate and migration rate, does not involve the exchange of microplastics in lake sediments and water bodies, which makes the simulation experiment have a large gap with the actual situation and results in inaccurate experimental data.

[0005] Therefore, a new technical solution needs to be researched to address the above problems. Summary of the Invention

[0006] In view of this, the present invention addresses the deficiencies of the existing technology, and its main objective is to provide a simulation method for the dynamic process of microplastic sedimentation and suspension in lake water-sediment systems. This method effectively solves the technical problems of high experimental costs and inaccurate experimental data obtained from current lake hydrodynamic disturbances in detecting the sedimentation and suspension process of microplastics in water-sediment systems.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A method for simulating the dynamic processes of microplastic sedimentation and suspension in a lake water-sediment system includes the following steps:

[0009] An indoor simulation system is constructed, including a sedimentation simulation module, which provides a sedimentation simulation pool and a first water tank, the first water tank supplying water to the sedimentation simulation pool via a peristaltic pump; and a suspension simulation module, which provides a suspension simulation pool and a second water tank, the second water tank supplying water to the suspension simulation pool via a peristaltic pump.

[0010] Water is continuously fed into the sedimentation simulation tank and the suspension simulation tank. When the water in the sedimentation simulation tank and the suspension simulation tank reaches a certain height, it can overflow to simulate dynamic water flow.

[0011] Provide sediment and introduce it into sedimentation simulation tanks and suspension simulation tanks;

[0012] Microplastic particles are provided and added to the first tank of the input water body in the sedimentation simulation pool; they are then added to the suspension simulation pool and mixed with the sediment in the suspension simulation pool.

[0013] During the sedimentation and suspension simulations, multiple time periods were set, and sediments and overlying water samples were taken in each time period to analyze the abundance of microplastic particles.

[0014] The beneficial effects of the simulation method for the dynamic process of microplastic sedimentation and suspension in a lake water-sediment system provided in this application are as follows: Compared with the prior art, by constructing an indoor simulation system, the sedimentation simulation tank and the suspension simulation tank continuously input water through peristaltic pumps and can overflow to simulate dynamic water flow; sediments are introduced into the sedimentation simulation tank and the suspension simulation tank to simulate the real lake water environment, that is, the in-situ environment of water and sediments, and different water flow rates are introduced to simulate the real water flow environment; water containing microplastic particles is introduced into the sedimentation simulation tank, and microplastic particles are mixed into the sediments in the suspension simulation tank; sediments and overlying water are collected at multiple time periods to analyze their microplastic particle abundance, thereby obtaining corresponding experimental data; it can be seen that this simulation method does not require the on-site deployment of corresponding devices, which reduces the difficulty of simulation experiments, saves time and effort, and reduces detection costs; at the same time, since sediments are introduced into each simulation tank to simulate the actual lake water-sediment system, it is beneficial to narrow the gap between the simulation experiment and the real situation, thereby improving the accuracy of the obtained experimental data.

[0015] As a preferred option: during the sedimentation simulation process, a sediment with a thickness of 10 cm is introduced into the sedimentation simulation tank, 15 L of water is injected and left to stand for several hours. After standing, the first water tank continuously inputs water into the sedimentation simulation tank through a peristaltic pump.

[0016] As a preferred option: after the microplastic particles are put into the first water tank, the microplastic particles are evenly dispersed in the water in the first water tank. The water containing microplastic particles in the first water tank is introduced from the water surface of the sedimentation simulation pool at a position of 1 cm and discharged through overflow.

[0017] As a preferred approach: during the suspension simulation process, a 10 cm thick layer of sediment is introduced into the suspension simulation tank; microplastic particles are added to the sediment in multiple batches and stirred evenly; then 15 L of water is injected and the mixture is left to stand for 24 hours.

[0018] As a preferred option: when the second water tank inputs water into the suspended simulation pool, it is input from 1 cm above the surface of the sediment and the water is discharged through overflow.

[0019] As a preferred option, the microplastic particles are blue polyamide particles, yellow polyethylene terephthalate particles, and red polystyrene particles. The size range of the blue polyamide particles, yellow polyethylene terephthalate particles, and red polystyrene particles is 200 μm to 2000 μm, and all of them have obvious pores and breakage marks on their surfaces.

[0020] As a preferred embodiment, the sediment contains clay, fine silt, coarse silt, fine sand, medium sand, and coarse sand, wherein the clay is less than 4 μm, the fine silt is 4 to 16 μm, the coarse silt is 16 to 63 μm, the fine sand is 63 to 200 μm, the medium sand is 200 to 500 μm, and the coarse sand is 500 to 2000 μm.

[0021] As a preferred approach: In the sedimentation simulation, the sedimentation simulation tank has a first sedimentation tank, a second sedimentation tank, a third sedimentation tank, and a fourth sedimentation tank. The water flow rate input to the first sedimentation tank is controlled by a peristaltic pump to be 500 ml / min, the water flow rate to the second sedimentation tank is 1000 ml / min, the water flow rate to the third sedimentation tank is 1500 ml / min, and the water flow rate to the fourth sedimentation tank is 2000 ml / min. Sediments of 0-2 cm and overlying water are collected in each sedimentation simulation tank at 0 min, 10 min, 30 min, 60 min, 120 min, 180 min, and 240 min, respectively.

[0022] As a preferred embodiment: In the suspension simulation, the suspension simulation tank has a first suspension tank, a second suspension tank, a third suspension tank, and a fourth suspension tank. The water flow rate input to the first suspension tank is controlled by a peristaltic pump to be 1000 ml / min, the water flow rate to the second suspension tank is 2000 ml / min, the water flow rate to the third suspension tank is 4000 ml / min, and the water flow rate to the fourth suspension tank is 8000 ml / min. Sediments of 0-2 cm and overlying water are collected in each sedimentation simulation tank at 0 min, 10 min, 30 min, 60 min, 120 min, 180 min, and 240 min, respectively.

[0023] As a preferred option, the following steps are also included:

[0024] Extraction of microplastic particles from overlying water:

[0025] Take 300ml of the overlying water and add 150ml of hydrogen peroxide (H2O2) solution in 2-3 portions, and let it stand at room temperature for 48 hours;

[0026] Shake the solution periodically every 2-3 hours until it becomes clear and transparent;

[0027] The above solution was filtered through a vacuum filter to transfer the microplastic particles to a glass fiber filter membrane. The glass fiber filter membrane was then stored in a filter membrane storage box and dried in an oven at 40°C for 48 hours.

[0028] Extraction of microplastic particles from sediments:

[0029] Weigh a 1000ml beaker, then collect the sediment, put it into the beaker, and weigh it again.

[0030] Add a substance with a density of 1.5-1.6 g / cm³ 3 500 ml of zinc chloride solution (ZnCl2) was added and stirred thoroughly for 30 minutes using a multi-stage magnetic stirrer, and then allowed to stand for 24 hours to separate the microplastic particles in the sediment and allow them to float on the water surface.

[0031] After repeating the above separation steps, add 200-300ml of hydrogen peroxide for further digestion, and use a vacuum filtration device for vacuum filtration to transfer the microplastic particles to the glass fiber filter membrane. Store the glass fiber filter membrane in a filter membrane storage box and dry it in an oven at 40℃ for 48 hours.

[0032] After extracting microplastics from the overlying water and sediments onto a glass fiber filter membrane, the glass fiber filter membrane obtained in the above steps is placed on an inverted fluorescence microscope to identify microplastic particles, and the size and number of microplastic particles are recorded. Attached Figure Description

[0033] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0034] Figure 1 This is a schematic diagram of a simulation method for the dynamic process of microplastic sedimentation and suspension in a lake water-sediment system provided in an embodiment of this application;

[0035] Figure 2 yes Figure 1 The diagram shown is a structural schematic of the sedimentation simulation tank.

[0036] Figure 3 yes Figure 1 The diagram shown is a structural schematic of the suspension simulation pool.

[0037] Figure 4 yes Figure 1 The diagram shows the operation of the first water tank inputting water into the sedimentation simulation pool.

[0038] Figure 5 yes Figure 1 The diagram shown illustrates the operation of the second water tank inputting water into the suspension simulation pool.

[0039] Figure 6 Here is a composition table of the sediments (Table 1).

[0040] The following are the labeling elements in the figure:

[0041] 10. Settling simulation module; 11. Settling simulation tank; 1101. Second inlet; 1102. Second outlet; 111. First settling tank; 112. Second settling tank; 113. Third settling tank; 114. Fourth settling tank; 12. First water tank; 121. First outlet; 13. Pneumatic mixer; 14. Air compressor;

[0042] 20. Suspension simulation module; 21. Suspension simulation tank; 2101. Third inlet; 2102. Third outlet; 211. First suspension tank; 212. Second suspension tank; 213. Third suspension tank; 214. Fourth suspension tank; 22. Second water tank;

[0043] 30. Sediment; 40. Microplastic particles; 51. First peristaltic pump; 52. Second peristaltic pump. Detailed Implementation

[0044] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of this application.

[0045] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as being "connected to" another component, it can be directly connected to or indirectly connected to that other component.

[0046] It should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0047] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0048] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0049] Before providing a detailed explanation of the embodiments of this application, the application scenarios of the embodiments of this application will be described first.

[0050] In existing technologies, the prevention and source identification of microplastic pollution in lakes typically utilizes in-situ water source testing or indoor simulations to provide data that reveals the suspension and sedimentation processes of microplastics in lakes. In-situ observation requires the installation of corresponding devices at the lake location. However, installing these devices in the field to collect data is not only difficult, but also inherently uncontrollable, making it impractical and costly. Indoor simulations currently only detect different movement states of microplastics, including sedimentation rate, initial migration rate, and migration rate. These simulations do not address the exchange of microplastics between lake water and sediment, particularly the suspension and sedimentation mechanisms of microplastics in the lake water-sediment system.

[0051] This application provides a simulation method for the dynamic process of microplastic sedimentation and suspension in a lake water-sediment system. The aim is to more realistically simulate the migration and diffusion process of microplastics in the lake water environment, reveal the sedimentation and suspension mechanism of microplastics in the lake water-sediment system, and provide a reference for the prevention and control of microplastic pollution and source identification.

[0052] Please refer to the following: Figures 1 to 6 The present application provides a method for simulating the dynamic process of microplastic sedimentation and suspension in a lake water-sediment system.

[0053] A method for simulating the dynamic processes of microplastic sedimentation and suspension in a lake water-sediment system includes the following steps:

[0054] An indoor simulation system is constructed, which includes a sedimentation simulation module 10 and a suspension simulation module 20. The sedimentation simulation module 10 provides a sedimentation simulation pool 11 and a first water tank 12, and the first water tank 12 supplies water to the sedimentation simulation pool 11 through a peristaltic pump. The suspension simulation module 20 provides a suspension simulation pool 21 and a second water tank 22, and the second water tank 22 supplies water to the suspension simulation pool 21 through a peristaltic pump.

[0055] Water is continuously input into the sedimentation simulation tank 11 and the suspension simulation tank 21. After the water in the sedimentation simulation tank 11 and the suspension simulation tank 21 reaches a certain height, it can overflow to simulate dynamic water flow.

[0056] Provide sediment 30 and put the sediment into sedimentation simulation tank 11 and suspension simulation tank 21;

[0057] Microplastic particles 40 are provided and added to the first water tank 12 into the sedimentation simulation tank 11; they are also added to the suspension simulation tank 21 and mixed with the sediment 30 in the suspension simulation tank 21.

[0058] During the sedimentation and suspension simulations, multiple time periods were set, and sediment samples (30%) and overlying water samples (40%) were taken in each time period to analyze the abundance of microplastic particles (40).

[0059] Specifically, by constructing an indoor simulation system, sedimentation simulation tank 11 and suspension simulation tank 21 continuously input water through peristaltic pumps and can overflow to simulate dynamic water flow; sediment 30 is introduced into sedimentation simulation tank 11 and suspension simulation tank 21 to simulate the real lake environment, i.e., the in-situ water-sediment environment; water containing microplastic particles 40 is introduced into sedimentation simulation tank 11, and microplastic particles 40 are mixed into the sediment in suspension simulation tank 21; sediment and overlying water are sampled at multiple time periods to analyze the abundance of microplastic particles 40, thereby obtaining corresponding experimental data; it can be seen that this simulation method does not require the on-site deployment of corresponding devices, reducing the difficulty of simulation experiments, saving time and effort, and reducing detection costs; at the same time, since sediment is introduced into each simulation tank to simulate the actual lake environment, reflecting the symbiotic system of water and sediment, it is beneficial to narrow the gap between the simulation experiment and the real situation, thereby improving the accuracy of the obtained experimental data.

[0060] It should be noted that regarding the addition of microplastic particles 40: In the sedimentation simulation module, microplastic particles 40 are added to the first water tank 12 and input into the sedimentation simulation pool 11 along with the water in the first water tank 12. That is to say, the water and sediment in the sedimentation simulation pool 11 do not contain microplastic particles 40 in the initial state. In the suspension simulation module, microplastic particles 40 are mixed in the sediment 30. That is to say, in the initial state, only the sediment 30 in the suspension simulation pool 21 contains microplastic particles 40. Through the flushing of water flow, the microplastic particles 40 in the sediment 30 will be suspended to the water body above the suspension simulation pool 21.

[0061] In some embodiments of this application, during the sedimentation simulation process, a 10 cm thick layer of sediment 30 is added to the sedimentation simulation tank 11, followed by the injection of 15 L of water and allowed to stand for several hours. After standing, the first water tank 12 continuously feeds water into the sedimentation simulation tank 11 via a peristaltic pump. After microplastic particles 40 are added to the first water tank 12, they are evenly dispersed in the water within the first water tank 12. The water containing microplastic particles 40 in the first water tank 12 is introduced from a position 1 cm above the water surface of the sedimentation simulation tank 11 and discharged via overflow.

[0062] Continuing from the above, during the suspension simulation process, a 10 cm thick layer of sediment 30 is added to the suspension simulation tank 21. Microplastic particles 40 are added to the sediment 30 in multiple batches and stirred thoroughly. Then, 15 L of water is added and the mixture is allowed to stand for 24 hours. When the second water tank 22 inputs water into the suspension simulation tank 21, it is introduced from 1 cm above the surface of the sediment 30 and the water is discharged through overflow. The addition of 15 L of water to the sedimentation simulation tank 11 and the suspension simulation tank 21 after the sediment 30 is added and allowed to stand is to more realistically simulate the state of the sediment 30 in a lake.

[0063] Please refer to the following: Figure 6Sediment 30 contained clay, fine silt, coarse silt, fine sand, medium sand, and coarse sand. Clay particles were less than 4 μm, fine silt particles were 4–16 μm, coarse silt particles were 16–63 μm, fine sand particles were 63–200 μm, medium sand particles were 200–500 μm, and coarse sand particles were 500–2000 μm. Since sediment properties may affect the suspension and settling process of microplastics, five sediment samples were selected before the experiment, and their water content, bulk density, pH, organic matter, and particle size were measured (see Table 1). During the experiment, these samples were simply placed into the corresponding simulation pools.

[0064] It should be noted that sediment water content refers to the ratio (%) of the mass of water in the sediment to the mass of the dry sediment, while sediment bulk density refers to the ratio (g / cm3) of the mass of the dried sediment to the volume of the sample. Therefore, sediment water content and bulk density are measured by comparing the weight of the sediment in the aluminum box before and after drying. Simultaneously, the organic matter content of the sediment was calculated according to the standard for soil organic matter determination (NY / T 1121.6-2006), and the pH value of the sediment was measured using a pH meter (STARTER3100 OHAUS, China). Sediment particle size was determined using a laser particle size analyzer (Master Sizer 2000, UK).

[0065] In some embodiments of this application, the microplastic particles 40 are blue polyamide particles, yellow polyethylene terephthalate (PET) particles, and red polystyrene particles. The size range of the blue polyamide particles, yellow PET particles, and red polystyrene particles is 200 μm to 2000 μm, and all have obvious pores and breakage marks on their surfaces. The blue polyamide particles, yellow PET particles, and red polystyrene particles used in the experiment were analyzed by a micro-infrared spectroscopy instrument (Nicolet IN10, USA), and their polymer matching degree was all higher than 90%. The size range of the blue polyamide particles, yellow PET particles, and red polystyrene particles is 200–2000 μm, and their microscopic morphology is similar to that of microplastic particles 40 in lake sediments and water bodies, with obvious pores and breakage marks on their surfaces, making the simulation experiment closer to actual conditions. By using blue polyamide particles, yellow polyethylene terephthalate particles, and red polystyrene particles, the entire motion can be visualized, and different types of microplastics can be distinguished, making subsequent microplastic identification more accurate.

[0066] Please refer to the following: Figures 1 to 5In some other embodiments of this application, the sedimentation simulation tank 11 has a first sedimentation tank 111, a second sedimentation tank 112, a third sedimentation tank 113 and a fourth sedimentation tank 114. The water flow rate input to the first sedimentation tank 111 is controlled by a peristaltic pump to be 500 ml / min, the water flow rate of the second sedimentation tank 112 is 1000 ml / min, the water flow rate of the third sedimentation tank 113 is 1500 ml / min and the water flow rate of the fourth sedimentation tank 114 is 2000 ml / min.

[0067] Continuing from the previous section, in this sedimentation simulation, water is fed into the first sedimentation tank 111 through pipe No. 15, into the second sedimentation tank 112 through pipe No. 36, into the third sedimentation tank 113 through pipe No. 73, and into the fourth sedimentation tank 114 through pipe No. 82. The peristaltic pump used is defined as the first peristaltic pump 51 (WT600F, China), which controls the flow rate of water entering the sedimentation tanks. Sediment 30 (0–2 cm) and overlying water in each sedimentation simulation tank 11 are collected at 0 min, 10 min, 30 min, 60 min, 120 min, 180 min, and 240 min to analyze the abundance of microplastic particles 40.

[0068] Please refer to the following: Figures 1 to 5 In some other embodiments of this application, the suspension simulation tank 21 has a first suspension tank 211, a second suspension tank 212, a third suspension tank 213 and a fourth suspension tank 214. The water flow rate input to the first suspension tank 211 is controlled by a peristaltic pump to be 1000 ml / min, the water flow rate of the second suspension tank 212 is 2000 ml / min, the water flow rate of the third suspension tank 213 is 4000 ml / min and the water flow rate of the fourth suspension tank 214 is 8000 ml / min.

[0069] Continuing from the previous section, in this suspension simulation, the second water tank 22 inputs water into the first suspension pool 211 through pipe No. 15, the second water tank 22 inputs water into the second suspension pool 212 through pipe No. 36, the second water tank 22 inputs water into the third suspension pool 213 through pipe No. 73, and the second water tank 22 inputs water into the fourth suspension pool 214 through pipe No. 82. Two peristaltic pumps are used, defined as the first peristaltic pump 51 (WT600F, China) and the second peristaltic pump 52 (YZ35, China). The first peristaltic pump 51 is used when the input water volume to the suspension pool is 1000ml and 2000ml, while the second peristaltic pump 52 is used for the other two groups. Sediment 30 (0–2cm) and overlying water in each suspension simulation pool 21 are collected at 0 min, 10 min, 30 min, 60 min, 120 min, 180 min, and 240 min to analyze the abundance of microplastic particles 40.

[0070] It should be noted that among the aforementioned water pipes, pipe No. 15 has an inner diameter of 5mm, pipe No. 36 has an inner diameter of 9mm, pipe No. 73 has an inner diameter of 10mm, and pipe No. 82 has an inner diameter of 13mm. All water pipes are transparent silicone flexible tubes, which have good wear resistance and will not be worn out in a short period of time. Meanwhile, the first water tank 12 and the second water tank 22 are both made of stainless steel. The dimensions of the first water tank are 1000mm×1000mm×1000mm, and the dimensions of the second water tank are 1000mm×500mm×500mm. The sedimentation simulation tank 11 and the suspension simulation tank 21 are both made of transparent plexiglass with a thickness of 8mm, which is beneficial for observing changes in the internal water environment during suspension and sedimentation experiments. The water used in the first water tank 12 and the second water tank 22 comes from a waterworks and does not contain obvious microplastic particles 40, which helps improve the accuracy of analyzing the number of microplastic particles 40.

[0071] Please refer to the following: Figures 1 to 3 In some embodiments of this application, a pneumatic mixer 13 is installed in the first water tank 12. The agitator 13 is located at the center of the first water tank 12. The pneumatic mixer 13 is driven by an air compressor 14 to agitate the microplastic particles 40 in the first water tank 12, so that the microplastic particles 40 can be evenly dispersed in the water in the first water tank 12. A first water outlet 121 is provided on the side of the first water tank 12 and the second water tank 22. The first water outlet 121 is located at half the height of the entire water tank.

[0072] A second inlet 1101 is provided on one side of the sedimentation simulation tank 11, and a second outlet 1102 is provided on the opposite side of the sedimentation simulation tank 11. The second inlet 1101 and the second outlet 1102 are located at the same height. The height of the sedimentation simulation tank 11 is 350 mm, and the second inlet 1101 is located 300 mm from the bottom of the sedimentation simulation tank 11. By setting the second inlet 1101 and the second outlet 1102 at the same height and opposite to each other, a real lake water flow environment can be simulated. Preferably, the second inlet 1101 and the second outlet 1102 are circular, and the centers of the second inlet 1101 and the second outlet 1102 are located on the same axis.

[0073] Continuing from the above, a third inlet 2101 is provided on one side of the suspension simulation tank 21, and a third outlet 2102 is provided on the other side of the suspension simulation tank 21. The height of the third inlet 2101 is lower than the height of the third outlet 2102. The height of the suspension simulation tank 21 is 350mm. The third inlet 2101 is located 110mm from the bottom of the suspension simulation tank 21, and the third outlet 2102 is located 300mm from the bottom of the suspension simulation tank 21. This structure allows water to enter through the lower-level third inlet 2101, flushing the sediment at the bottom of the suspension simulation tank 21 to simulate the actual lake environment and improve the accuracy of microplastic abundance data analysis.

[0074] In this embodiment of the application, microplastic particles 40 are extracted from the overlying water:

[0075] Take 300ml of the overlying water and add 150ml of hydrogen peroxide (H2O2) solution in 2-3 portions, and let it stand at room temperature for 48 hours;

[0076] Shake the solution periodically every 2-3 hours until it becomes clear and transparent;

[0077] The above solution was filtered through a vacuum filter to transfer the microplastic particles 40 to the glass fiber filter membrane. The glass fiber filter membrane was stored in a filter membrane storage box and dried in an oven at 40°C for 48 hours.

[0078] Extraction of microplastic particles from sediments: 40

[0079] Weigh a 1000ml beaker, then collect the sediment (30) and put it into the beaker and weigh it again;

[0080] Add a substance with a density of 1.5-1.6 g / cm³ 3 500 ml of zinc chloride solution (ZnCl2) was added and stirred thoroughly for 30 min using a multi-stage magnetic stirrer, and then allowed to stand for 24 hours to allow 40% of the microplastic particles in the sediment to separate and float on the water surface.

[0081] After repeating the above separation steps, add 200-300ml of hydrogen peroxide for further digestion, and use a vacuum filtration device for vacuum filtration to transfer the microplastic particles to the glass fiber filter membrane. Store the glass fiber filter membrane in a filter membrane storage box and dry it in an oven at 40°C for 48 hours.

[0082] Glass fiber membranes obtained from the extraction of microplastics from the overlying water and sediments were placed on an inverted fluorescence microscope to identify microplastic particles 40 and record their size and number. This study aimed to reveal the sedimentation and suspension mechanisms of microplastics in the lake water-sediment system and provide a reference for the prevention and control of microplastic pollution and source identification.

[0083] The above are merely preferred embodiments of the present invention, and only specifically describe the technical principles of the present invention. These descriptions are only for explaining the principles of the present invention and should not be construed as limiting the scope of protection of the present invention in any way. Based on this explanation, any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention, as well as other specific embodiments of the present invention that can be conceived by those skilled in the art without creative effort, should be included within the scope of protection of the present invention.

Claims

1. A method for simulating the settling and suspension dynamic processes of microplastics in a lake water-sediment system, characterized in that: Includes the following steps: An indoor simulation system is constructed, including a sedimentation simulation module (10), which provides a sedimentation simulation pool (11) and a first water tank (12), wherein the first water tank (12) inputs water into the sedimentation simulation pool (11) via a peristaltic pump; and a suspension simulation module (20), which provides a suspension simulation pool (21) and a second water tank (22), wherein the second water tank (22) inputs water into the suspension simulation pool (21) via a peristaltic pump; Water is continuously input into the sedimentation simulation tank (11) and the suspension simulation tank (21). After the water in the sedimentation simulation tank (11) and the suspension simulation tank (21) reaches a certain height, it can overflow to simulate dynamic water flow. Provide sediment (30) and put the sediment into a settling simulation tank (11) and a suspension simulation tank (21); Microplastic particles (40) are provided and put into the first water tank (12) of the sedimentation simulation pool (11); they are put into the suspension simulation pool (21) and mixed with the sediment (30) in the suspension simulation pool (21); During the sedimentation and suspension simulations, multiple time periods were set, and sediments (30) and overlying water were collected in each time period to analyze the abundance of microplastic particles (40). Among them, a second inlet (1101) is provided on one side of the sedimentation simulation tank (11), and a second outlet (1102) is provided on the opposite side of the sedimentation simulation tank (11). The second inlet (1101) and the second outlet (1102) are located at the same height. A third inlet (2101) is provided on one side of the suspension simulation tank (21), and a third outlet (2102) is provided on the other side of the suspension simulation tank (21). The height of the third inlet (2101) is lower than the height of the third outlet (2102). In the sedimentation simulation, the sedimentation simulation pool (11) has a first sedimentation pool (111), a second sedimentation pool (112), a third sedimentation pool (113) and a fourth sedimentation pool (114). The water flow rate input to the first sedimentation pool (111) is controlled by a peristaltic pump to be 500 ml / min, the water flow rate of the second sedimentation pool (112) is 1000 ml / min, the water flow rate of the third sedimentation pool (113) is 1500 ml / min and the water flow rate of the fourth sedimentation pool (114) is 2000 ml / min. 0-2 cm sediment (30) and overlying water are collected in each sedimentation simulation pool (11) at 0 min, 10 min, 30 min, 60 min, 120 min, 180 min and 240 min respectively. In the suspension simulation, the suspension simulation pool (21) has a first suspension pool (211), a second suspension pool (212), a third suspension pool (213) and a fourth suspension pool (214). The water flow rate input to the first suspension pool (211) is controlled by a peristaltic pump to be 1000 ml / min, the water flow rate of the second suspension pool (212) is 2000 ml / min, the water flow rate of the third suspension pool (213) is 4000 ml / min, and the water flow rate of the fourth suspension pool (214) is 8000 ml / min. 0-2 cm sediment (30) and overlying water are collected in each sedimentation simulation pool (21) at 0 min, 10 min, 30 min, 60 min, 120 min, 180 min and 240 min respectively. There are two peristaltic pumps, defined as a first peristaltic pump (51) and a second peristaltic pump (52). The first peristaltic pump (51) is used when the water input to the suspension tank is 1000ml and 2000ml, and the second peristaltic pump (52) is used for the other two groups.

2. The method according to claim 1, wherein: During the sedimentation simulation process, a sediment (30) with a thickness of 10 cm was added to the sedimentation simulation tank (11), 15 L of water was injected and left to stand for several hours. After standing, the first water tank (12) continuously input water into the sedimentation simulation tank (11) through a peristaltic pump.

3. The method according to claim 2, wherein: After the microplastic particles (40) are put into the first water tank (12), the microplastic particles (40) are evenly dispersed in the water in the first water tank (12). The water containing the microplastic particles (40) in the first water tank (12) is input from the water surface of the sedimentation simulation pool (11) at a position of 1 cm and discharged through overflow.

4. The method for simulating the dynamic process of microplastic sedimentation and suspension in a lake water-sediment system according to claim 1, characterized in that: During the suspension simulation process, a 10 cm thick sediment (30) was added to the suspension simulation pool (21); microplastic particles (40) were added to the sediment (30) in multiple batches and stirred evenly, and then 15 L of water was injected and left to stand for 24 hours.

5. The method for simulating the dynamic process of microplastic sedimentation and suspension in a lake water-sediment system according to claim 4, characterized in that: When the second water tank (22) inputs water into the suspension simulation pool (21), it is input from 1 cm above the surface of the sediment (30) and the water is discharged through overflow.

6. The method for simulating the dynamic process of microplastic sedimentation and suspension in a lake water-sediment system according to claim 1, characterized in that: The microplastic particles (40) are blue polyamide particles, yellow polyethylene terephthalate particles and red polystyrene particles. The size range of the blue polyamide particles, yellow polyethylene terephthalate particles and red polystyrene particles is 200 μm to 2000 μm, and all of them have obvious small pores and broken traces on their surfaces.

7. The method for simulating the dynamic process of microplastic sedimentation and suspension in a lake water-sediment system according to claim 1, characterized in that: The sediment (30) contains clay, fine silt, coarse silt, fine sand, medium sand and coarse sand, wherein the clay is less than 4 μm, the fine silt is 4 to 16 μm, the coarse silt is 16 to 63 μm, the fine sand is 63 to 200 μm, the medium sand is 200 to 500 μm and the coarse sand is 500 to 2000 μm.

8. A method for simulating the dynamic processes of microplastic sedimentation and suspension in a lake water-sediment system according to any one of claims 1 to 7, characterized in that: It also includes the following steps: Extraction of microplastic particles (40) from overlying water: Take 300ml of the supernatant water, add 150ml of hydrogen peroxide solution in 2-3 portions, and let stand at room temperature for 48 hours; Shake the solution periodically every 2-3 hours until it becomes clear and transparent; The above solution was filtered through a vacuum filter to transfer the microplastic particles (40) to the glass fiber filter membrane. The glass fiber filter membrane was stored in a filter membrane storage box and dried in an oven at 40°C for 48 hours. Extraction of microplastic particles (40) from sediments: Weigh a 1000ml beaker, then collect the sediment (30) and put it into the beaker and weigh it again; A 500 ml zinc chloride solution with a density of 1.5-1.6 g / cm 3 was added, and after being fully stirred for 30 min using a multi-union magnetic stirrer, it was left to stand for 24 hours, so that the microplastic particles in the sediment were separated and floated on the water surface; After repeating the above steps, add 200-300ml of hydrogen peroxide for further digestion, and use a vacuum filtration device for vacuum filtration to transfer the microplastic particles to the glass fiber filter membrane. Store the glass fiber filter membrane in a filter membrane storage box and dry it in an oven at 40℃ for 48 hours. After extracting microplastics from the overlying water and sediments onto a glass fiber filter membrane, the obtained glass fiber filter membrane was placed on an inverted fluorescence microscope to identify microplastic particles, and the size and number of microplastic particles (40) were recorded.

Images