Micro-plastic motion trail prediction method and device and medium

Abstract

The invention provides a micro-plastic motion trail prediction method and device and a medium. The method comprises the steps that the type of micro-plastic particles to be measured is obtained; the types of the micro-plastic particles to be measured are input into the trained river micro-plastic particle migration trajectory prediction model, a prediction result is obtained, and the obtaining process of the trained river micro-plastic particle migration trajectory prediction model at least comprises the following steps that motion rules of different types of micro-plastic particles are obtained; on the basis of the movement rules of the different types of micro-plastic particles, a particle tracking method is adopted, and the movement tracks of the different types of micro-plastic particles in the water body are obtained. According to the method, the model is trained by comprehensively considering the characteristics of different types of micro-plastics and the actual movement rules of the micro-plastics in the water body, so that the prediction result can better fit the actual situation.

Description

Technical Field

[0001] The present invention relates to the technical field of microplastic particle migration, and specifically provides a method, device and medium for predicting the movement trajectory of microplastics. Background Art

[0002] As a new type of persistent pollutant, microplastic particles have become one of the hot topics of global academic circles in recent years. Due to the small particle size and low density of microplastic particles, they are easily migrated and transformed under the action of external forces such as strong winds, rivers, ocean currents, and tides. Studies have found that in the marine system, microplastic particles are spread all over the world due to the movement of ocean currents. Microplastic particles of different abundances and particle sizes have been detected in remote areas such as coastlines of various continents, Antarctic islands and the Arctic. They are also common in freshwater waters such as rivers and lakes, and even in organisms such as plankton, fish and birds, as well as in table salt, tap water and bottled mineral water. Microplastic particles have been detected. The source of microplastic particles in the environment is closely related to human lifestyle. Among them, sewage treatment plants are an important way for microplastic particles to enter the environment. Due to differences in sewage sources and treatment processes, there are certain differences in the removal effect of microplastic particles and the concentration of tailwater discharge of different sewage treatment plants. Although the emission concentration of microplastic particles in sewage treatment plants is low, the amount of microplastic particles released by their huge daily treatment scale cannot be ignored.

[0003] Most current research focuses on marine microplastic particle pollution, and research on the migration mechanism of microplastic particles in terrestrial freshwater environments is relatively rare. The movement trajectory and driving factors of microplastic particles in freshwater environments are quite different from those in marine environments. For example, the water flow pattern is more complex and the movement state transitions of microplastic particles are more frequent. In addition, the freshwater environment is closely related to human survival and development, and should be the focus of microplastic particle pollution prevention and control. At the same time, due to the extremely complex composition of microplastic particles, the physical and chemical properties of different types of microplastic particles vary greatly, and the migration and transformation laws in the water environment are also very different, which poses a huge challenge to the prevention and control of microplastic particle pollution.

[0004] Therefore, the field needs a new microplastic movement trajectory prediction solution to solve the above problems. Summary of the invention

[0005] In order to overcome the above-mentioned defects, the present invention is proposed to provide a solution or at least partially solve the problem of being unable to accurately and effectively predict the movement trajectory of microplastics.

[0006] In the first aspect, the present invention provides a method for predicting the movement trajectory of microplastics, comprising: obtaining the type of microplastic particles to be tested; inputting the type of microplastic particles to be tested into a trained river microplastic particle migration trajectory prediction model to obtain a prediction result, wherein the acquisition process of the trained river microplastic particle migration trajectory prediction model includes at least the following steps: obtaining the movement laws of different types of microplastic particles; using a particle tracking method based on the movement laws of different types of microplastic particles to obtain the movement trajectories of different types of microplastic particles in the water body.

[0007] In one technical solution of the above-mentioned microplastic motion trajectory prediction method, a particle tracking method is used based on the motion laws of different types of microplastic particles to obtain the motion trajectories of different types of microplastic particles in the water body, and the process includes at least the following steps: selecting a suitable time step, and for each time step, using the particle displacement formula to calculate the horizontal and vertical displacements based on the type of microplastics and the motion laws of the microplastic particles; based on the calculated horizontal and vertical displacements, updating the position of the microplastic particles after each time step; as the time step continues to advance, repeating the above-mentioned displacement calculation and position update process to obtain multiple position points, connecting all the position points in chronological order in sequence to obtain the complete motion trajectory of the microplastic particles in the water body.

[0008] In one technical solution of the above-mentioned microplastic motion trajectory prediction method, the process of using the particle displacement formula to calculate the horizontal and vertical displacements based on the type of microplastics and the movement laws of the microplastic particles includes: obtaining the horizontal migration speed and vertical sedimentation speed of different types of microplastic particles in the water body based on the movement laws of different types of microplastic particles; obtaining the horizontal and vertical displacements of the microplastic particles based on the horizontal migration speed and vertical sedimentation speed of different types of microplastic particles in the water body.

[0009] In a technical solution of the above-mentioned microplastic motion trajectory prediction method, the process of obtaining the horizontal and vertical displacements of the microplastic particles based on the horizontal migration speed and vertical sedimentation speed of different types of microplastic particles in the water body includes: substituting the horizontal migration speed and vertical sedimentation speed of different types of microplastic particles in the water body into the particle displacement formula to obtain the horizontal and vertical displacements of the microplastic particles; the method includes at least the following steps to obtain the particle displacement formula: considering the microplastic particles as the comprehensive result of horizontal and vertical movement, establishing Lag range particle tracking model; in the horizontal direction, the particle migration velocity in the water flow and the horizontal component of the random velocity caused by the turbulent effect are combined, and based on the turbulence theory, the random velocity part is expressed as a form related to the horizontal turbulent diffusion coefficient and the time step. At the same time, the deterministic horizontal migration velocity is considered to derive the horizontal displacement equation; in the vertical direction, the sedimentation rate of microplastics and the vertical random velocity caused by the turbulent effect are considered, and it is expressed as a form related to the vertical turbulent diffusion coefficient and the time step. Combined with the turbulent diffusion coefficient expression, the vertical displacement equation is derived.

[0010] In one technical solution of the above-mentioned microplastic motion trajectory prediction method, based on the motion laws of different types of microplastic particles, the process of obtaining the horizontal migration speed and vertical sedimentation speed of different types of microplastic particles in the water body includes: obtaining the flow velocity of different types of microplastic particles at different depths in the water body; analyzing the driving force in the horizontal direction and the vertical force on different types of microplastic particles in the water body, and obtaining the motion equations of different types of microplastic particles in the water body; substituting the obtained flow velocity at different depths into the corresponding motion equations of different types of microplastic particles in the water body, and calculating the horizontal migration speed and vertical sedimentation speed of each type of microplastic particles in the water body.

[0011] In one technical solution of the above-mentioned microplastic movement trajectory prediction method, the process of obtaining the flow velocity of different types of microplastic particles at different depths in the water body includes: obtaining the position and movement state of different types of microplastic particles in the water body; adopting layered processing for the flow velocity at different depths, and obtaining the flow velocity of different types of microplastic particles at different depths based on the one-dimensional hydrodynamic model of the river.

[0012] In one technical solution of the above-mentioned microplastic movement trajectory prediction method, the process of obtaining the flow velocity of different types of microplastic particles at different depths based on the one-dimensional hydrodynamic model of the river includes: obtaining relevant data of the water body, the relevant data including: cross-sectional average flow velocity, friction flow velocity, and water body depth; based on the relevant data of the water body and the current depth of the microplastic particles in the water body, calculating the flow velocity of each type of microplastic particles at different depths.

[0013] In a second aspect, an electronic device includes a processor and a storage device, the storage device is suitable for storing multiple program codes, and the program codes are suitable for being loaded and run by the processor to execute the microplastic motion trajectory prediction method of any one of the technical solutions of the above-mentioned microplastic motion trajectory prediction method.

[0014] In a third aspect, the present invention provides a computer-readable storage medium storing a plurality of program codes, wherein the program codes are suitable for being loaded and run by a processor to execute a method for predicting the motion trajectory of microplastics according to any one of the technical solutions of the above-mentioned method for predicting the motion trajectory of microplastics.

[0015] The above one or more technical solutions of the present invention have at least one or more of the following beneficial effects:

[0016] In the technical solution for implementing the present invention, the present invention provides a method for predicting the movement trajectory of microplastics, including: obtaining the type of microplastic particles to be tested; inputting the type of microplastic particles to be tested into a trained river microplastic particle migration trajectory prediction model to obtain a prediction result, wherein the acquisition process of the trained river microplastic particle migration trajectory prediction model includes at least the following steps: obtaining the movement laws of different types of microplastic particles; using a particle tracking method based on the movement laws of different types of microplastic particles to obtain the movement trajectories of different types of microplastic particles in the water body. Compared with the prior art, the beneficial effect of the microplastic movement trajectory prediction method provided by the present invention is: the method trains the model by comprehensively considering the characteristics of different types of microplastics and their actual movement laws in the water body, so that the prediction results can be more in line with the actual situation. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The disclosure of the present invention will become more easily understood with reference to the accompanying drawings. It will be readily understood by those skilled in the art that these drawings are only for illustrative purposes and are not intended to limit the scope of protection of the present invention. In addition, similar numbers in the drawings represent similar components, wherein:

[0018] Figure 1 1 is a schematic flow chart of the main steps of a method for predicting the movement trajectory of microplastics according to an embodiment of the present invention;

[0019] Figure 2 It is a flow chart of obtaining the horizontal migration speed and vertical sedimentation speed of different types of microplastic particles in water based on the movement laws of different types of microplastic particles according to an embodiment of the present invention. DETAILED DESCRIPTION

[0020] Some embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only used to explain the technical principles of the present invention and are not intended to limit the protection scope of the present invention.

[0021] Embodiment 1

[0022] See attached Figure 1 , Figure 1 FIG. 1 is a schematic flow chart of the main steps of a method for predicting the movement trajectory of microplastics according to an embodiment of the present invention. Figure 1 As shown, the method for predicting the movement trajectory of microplastics in the embodiment of the present invention mainly includes the following steps S1-S2.

[0023] Step S1, obtaining the type of microplastic particles to be tested;

[0024] In this embodiment, the movement states of different types of microplastic particles in water bodies can be divided into types such as drifting matter, suspended matter, and bed load.

[0025] Step S2, input the type of microplastic particles to be tested into the trained river microplastic particle migration trajectory prediction model to obtain a prediction result, wherein the acquisition process of the trained river microplastic particle migration trajectory prediction model includes at least the following steps: obtaining the motion laws of different types of microplastic particles; using particle tracking method based on the motion laws of different types of microplastic particles to obtain the motion trajectories of different types of microplastic particles in the water body.

[0026] In this embodiment, the special properties and movement mechanisms of different types of particles are taken into account. By using the particle tracking method based on the movement laws of different types of microplastic particles, a more realistic model of the movement trajectory of microplastic particles in water can be constructed. For example, for suspended microplastics, the particle tracking method can be used to consider their suspension and sedimentation processes at different water depths and flow velocities. By continuously tracking in time and space, the real movement trajectory can be obtained, thereby providing a more accurate data basis for subsequent prediction models.

[0027] In one embodiment, step S2, using a particle tracking method based on the movement laws of different types of microplastic particles to obtain the movement trajectories of different types of microplastic particles in the water body, comprises at least the following steps:

[0028] Step S21, select a suitable time step, for each time step, based on the type of microplastics, the movement law of microplastic particles, use the particle displacement formula to calculate the displacement in the horizontal and vertical directions. In this embodiment, the particle displacement formula is used to calculate the displacement in the horizontal and vertical directions respectively according to the specific type of microplastic particles and their corresponding movement law. For example, in the horizontal direction, the movement of the drift material may be mainly affected by the surface velocity of the water flow and the wind, and its horizontal displacement calculation may involve parameters such as the surface velocity of the water flow, the wind speed, and the angle between the wind direction and the water flow direction; the horizontal displacement of the suspended material may be closely related to the water flow velocity at its depth; the horizontal displacement of the bed material may be related to factors such as the velocity at the bottom of the river and its own critical starting velocity. In the vertical direction, the vertical displacement of drift sediment may be different from other types due to factors such as buoyancy and lifting force; the vertical displacement of suspended sediment will be affected by its own sedimentation velocity, which is related to its particle size, density and other factors; the calculation method of vertical displacement of bed sediment before and after sinking to the bottom of the water is also different, which may be related to factors such as the bottom flow velocity of the water body and its own critical resuspension velocity. By substituting these parameters related to the type and movement law of microplastics into the corresponding particle displacement formula, the horizontal and vertical displacement of microplastic particles in each time step can be calculated.

[0029] Step S22, based on the calculated horizontal and vertical displacements, the position of the microplastic particles after each time step is updated. In the present embodiment, because the displacement describes the change in the position of the particle over a period of time, the position of the particle at the end of the previous time step is vector-added with the horizontal displacement and vertical displacement calculated by the current time step, and the new position of the particle at the end of the current time step can be obtained. In this way, the position of the particle is continuously updated according to the displacement calculated each time, and the movement path of the particle in the water body can be gradually tracked.

[0030] Step S23: As the time step continues to advance, the above displacement calculation and position update process is repeated to obtain multiple position points, and all position points are connected in chronological order to obtain the complete movement trajectory of the microplastic particles in the water body.

[0031] In one embodiment, step S21, based on the type of microplastics and the movement law of microplastic particles, the process of using the particle displacement formula to calculate the displacement in the horizontal direction and the vertical direction includes:

[0032] Step S211, based on the movement laws of different types of microplastic particles, obtain the migration speed of different types of microplastic particles in the water body in the horizontal direction and the sedimentation speed in the vertical direction. In this embodiment, different types of microplastic particles (such as drift, suspended matter, and bed load) have their own unique movement laws in the water body. These laws are determined by a combination of factors, including the physical properties of the microplastic particles themselves (such as density, shape, particle size, etc.) and the force of the water environment on the particles (such as water flow drag, buoyancy, gravity, wind drag, etc.).

[0033] Step S212: obtaining the horizontal and vertical displacements of microplastic particles based on the horizontal migration speed and vertical sedimentation speed of different types of microplastic particles in the water body.

[0034] In one embodiment, the process of obtaining the horizontal and vertical displacements of microplastic particles based on the horizontal migration speed and vertical sedimentation speed of different types of microplastic particles in water includes: substituting the horizontal migration speed and vertical sedimentation speed of different types of microplastic particles in water into the particle displacement formula to obtain the horizontal and vertical displacements of the microplastic particles;

[0035] The method at least includes the following steps to obtain the particle displacement formula: the microplastic particles are regarded as the comprehensive result of horizontal and vertical motion, and a Lagrange particle tracking model is established; in the horizontal direction, the particle migration velocity in the water flow and the horizontal component of the random velocity caused by the turbulent effect are combined, and the random velocity part is expressed as a form related to the horizontal turbulent diffusion coefficient and the time step based on the turbulence theory, and the deterministic horizontal migration velocity is considered at the same time, so as to derive the horizontal displacement equation; in the vertical direction, the deterministic motion part of the microplastic sedimentation rate and the vertical random velocity caused by the turbulent effect are considered, and they are expressed as a form related to the vertical turbulent diffusion coefficient and the time step, and then the vertical displacement equation is derived by combining the turbulent diffusion coefficient expression obtained by experience or theory.

[0036] In this embodiment, the Lagrange particle tracking model:

[0037]

[0038] x t+1 =x t +Δt[U(x,t)+U′(x,t)]

[0039] Where: x is the particle coordinate; U is the particle migration speed in the water flow; U′ is the random speed caused by the turbulence effect; t is the time information; x t+1 、x tare the horizontal coordinates of the particle at time t+1 and time t respectively; Δt is the time step.

[0040] The particle displacement equation is derived:

[0041]

[0042] Where: V is the horizontal velocity vector of the microplastic particle, m / s; R is a vector composed of independent random components with zero mean and unit variance, representing random motion (R x is the component along the x direction, R x ∈[-1, 1]; R z is the component along the z direction); z is the distance from the water surface to the location of the microplastics; Z t+1 , Z t are the vertical coordinates of the particles at time t+1 and t, respectively; v is the sedimentation rate of microplastics, m / s; D v is the vertical turbulent diffusion coefficient.

[0043] Alternatively, in an alternative manner, the specific manner of obtaining the horizontal and vertical displacements of microplastic particles based on the horizontal migration speed and vertical sedimentation speed of different types of microplastic particles in water bodies can also be: Horizontal direction: If it is known that the horizontal migration speed V(t) of microplastic particles is a function of time t, then the displacement can be obtained by integrating the speed function over the time interval [t1, t2]. That is, horizontal displacement The integration method can also be used for the vertical sedimentation velocity v(t). In addition, the forward difference method can also be used. When the horizontal migration velocity V(t0), V(t1), V(t2), ... of microplastic particles at a series of discrete time points t0, t1, t2, ... is known, the forward difference can be used to approximate the displacement. For the time step Δt, at the time point t i to i+1 The horizontal displacement is approximately ΔX i ≈V(t i )Δt. Vertical direction: Similarly, for the vertical settling velocity v(t), the vertical displacement is approximately ΔZ i ≈v(t i )Δt.

[0044] Of course, the process of obtaining the horizontal and vertical displacement of microplastic particles based on the horizontal migration speed and vertical sedimentation speed of different types of microplastic particles in water is not limited to the above-mentioned situations. No matter what the situation is, as long as the horizontal and vertical displacement of microplastic particles can be obtained, it will be sufficient.

[0045] In one embodiment, Figure 2As shown, step S211, based on the movement laws of different types of microplastic particles, the process of obtaining the horizontal migration speed and vertical sedimentation speed of different types of microplastic particles in the water body includes:

[0046] Step S2111, obtain the flow velocity of different types of microplastic particles at different depths in the water body; In this embodiment, when studying the movement of microplastic particles in the water body, the water body flow velocity is a key factor. Because the movement of microplastic particles is greatly affected by the water flow, the flow velocity at different depths is different, which will cause the movement state of microplastic particles in the horizontal and vertical directions to be different. For example, on the surface of the water body, the flow velocity may be large, and as the depth increases, the flow velocity usually decreases gradually. For different types of microplastic particles (such as drift, suspended matter, and bed load), their position distribution in the water body is different, and the flow velocity effect they are subjected to is also different. The flow velocity at different depths can be obtained by combining field measurement and theoretical calculation. Field measurement can use a flow meter, which is placed at different depths of the water body to directly measure the water flow velocity at the position. At the same time, the flow velocity at different depths can also be calculated by a theoretical model based on hydraulic principles and known boundary conditions of rivers or water bodies (such as riverbed shape, slope, flow, etc.).

[0047] Step S2112: Analyze the driving force in the horizontal direction and the vertical force on different types of microplastic particles in the water body to obtain the motion equations of different types of microplastic particles in the water body.

[0048] In this embodiment, in the horizontal direction, the movement of the drifting material is mainly affected by the surface velocity of the water flow and the wind drag, so the horizontal migration speed may be a function of the surface velocity of the water flow and factors such as wind speed and wind direction. For example, the formula for its horizontal migration speed is V f =k1u0+c w ·u w cosθ, where: V f is the drift rate, m / s; u0 is the surface velocity of the water flow, m / s; u w is the wind speed on the water surface; c w is the wind drift coefficient; θ is the angle between wind direction and water flow direction; k1 is the drift coefficient.

[0049] The horizontal movement of suspended sediment mainly depends on the drag force of water flow. Its horizontal migration speed is usually positively correlated with the water flow velocity u(z) at its depth, which can be expressed by the formula V m =k2u(z) to calculate. Where: V m is the migration rate of suspended matter particles, m / s; k2 is the suspension coefficient; u(z) is the water flow velocity at depth Z, m / s.

[0050] The bedload particles at the bottom of natural rivers generally move in the form of rolling, sliding, jumping, etc., such as silt, pebbles, etc. The movement state of microplastics at the bottom of the river is related to the flow velocity at the bottom of the river. The fitting of the horizontal velocity formula of bedload was based on the calculation formula of Shamov's sediment movement rate, and the bedload microplastic movement rate formula was obtained as follows: V p is the displacement rate, m / s; h is the water depth, m; u s is the critical starting flow rate, m / s; d s is the equivalent particle size, mm.

[0051] According to the hydraulic experiment, the calculation formula of the critical starting velocity and critical resuspension velocity of microplastic particles is fitted:

[0052]

[0053] Where: u s is the critical starting flow velocity, m / s; u r , is the critical resuspension velocity, m / s; ρ s is the density of microplastics, kg / m 3 ; ρ0 is the density of water, kg / m 3 ; The meanings of other symbols are the same as before.

[0054] In the vertical direction, the vertical movement of microplastics mainly considers the effects of vertical forces on microplastics, namely gravity, buoyancy, lifting force and vertical turbulence. The gravity of the drifting material is less than the combined force of buoyancy and lifting force, so assuming that the vertical displacement is mainly affected by turbulence, the sedimentation rate v f =0.

[0055] Vertical settling velocity v of suspended matter m The sedimentation rate formula is related to the particle size, shape and density of the microplastics themselves, and is fitted through experiments:

[0056]

[0057] Where: v m is the sedimentation rate of suspended microplastics, m / s; t s is the sedimentation time, s.

[0058] The process of bed load from entering the water body to sinking to the bottom is the same as that of suspended load. When the bed load sinks to the bottom of the water, the calculation of the vertical position depends on the relationship between the bottom flow velocity of the water body and the critical starting flow velocity and the critical resuspension flow velocity. Based on the above description, the bottom flow velocity formula of bed load microplastics is derived:

[0059] v p =A1u s -A2u r

[0060]

[0061] Where: v p is the sedimentation rate of microplastics in bed load, m / s; u is the bottom flow velocity of the water body, m / s; other symbols have the same meanings as before.

[0062] Microplastics of different densities have different turbulence levels at different locations. According to the results of hydraulic experiment, the drift particle R z The range is set to [-0.5, 0.5], and the suspended particles R z The range is set to [-1, 1], and the load particles R z The range is set to [-0.1, 0.1].

[0063] Step S2113: Substitute the obtained flow velocities at different depths into the corresponding motion equations of different types of microplastic particles in the water body, and calculate the horizontal migration velocity and vertical sedimentation velocity of each type of microplastic particles in the water body.

[0064] In one embodiment, step S2111, the process of obtaining the flow velocity of different types of microplastic particles at different depths in the water body includes:

[0065] Obtain the location and movement status of different types of microplastic particles in water bodies;

[0066] The flow velocities at different depths are processed in layers, and the flow velocities of different types of microplastic particles at different depths are obtained based on the one-dimensional hydrodynamic model of the river.

[0067] In this embodiment, the position of the microplastic particles in the water body is crucial to determine the flow rate impact on it. The flow rate at different positions (such as the surface, middle or bottom of the water body) is different, and different types of microplastic particles (drift, suspended matter, and bedload) have different distribution tendencies in the water body. For example, drift is usually located near the surface of the water body, suspended matter is suspended within a certain depth range of the water body, and bedload is mainly at the bottom of the water body. The motion state of the microplastic particles (such as horizontal movement speed, vertical sedimentation or ascent speed, etc.) will also affect its perception of the flow rate. If a microplastic particle is moving horizontally at a fast speed, it passes through more water areas of different depths per unit time, so the comprehensive impact of the flow rate at different depths on it needs to consider its motion state to accurately measure. Moreover, the motion state may also be interrelated with the force situation of the particle, such as a suspended matter with a faster vertical sedimentation speed, when it passes through different depths during the descent, the water flow resistance (related to the flow rate) and the combined force of its own gravity will change its motion state, and its motion state will also react to the measurement and understanding of the flow rate.

[0068] In addition, the flow velocity in the water body usually changes in the vertical direction, showing a certain distribution pattern from the surface to the bottom of the water body. In the vertical direction, microplastics in different motion states are located in different positions: drifting matter moves on the surface of the water body; suspended matter moves between the surface and the bottom of the water body; bedload rolls or remains stationary at the bottom of the water body, and the change in motion state will only occur when the flow velocity reaches the critical speed. The flow velocity is different at different depths, so the flow velocity at different depths is treated in layers.

[0069] Alternatively, in an alternative approach, the specific method for obtaining the flow velocity of different types of microplastic particles at different depths can also be: Two-dimensional hydrodynamic model of the river: The two-dimensional hydrodynamic model takes into account the changes in water flow on a plane (usually the horizontal xy plane), including not only the flow velocity along the mainstream direction of the river, but also the lateral flow velocity changes. This model can more accurately describe the water flow conditions in complex terrains such as river bends and estuaries. By stratifying the water body in the vertical direction, combining boundary conditions (such as riverbank shape, bottom topography, inflow and outflow conditions, etc.) and fluid mechanics equations (such as shallow water equations), the flow velocity distribution at different depths can be simulated.

[0070] Alternatively, in an alternative approach, the specific method for obtaining the flow velocity of different types of microplastic particles at different depths can also be: Logarithmic flow velocity distribution formula: In a relatively stable water environment such as open channel flow, the logarithmic flow velocity distribution formula It is a commonly used method to estimate the flow velocity at different depths. Where u(z) is the flow velocity at depth, u* is the friction velocity, κ is the Karman constant (usually about 0.4), and is the roughness height.

[0071] Alternatively, in an alternative approach, the specific method for obtaining the flow velocity of different types of microplastic particles at different depths can also be: for some small, regularly shaped water channels, such as irrigation channels, small drainage channels, etc., the flow velocity of different types of microplastic particles at different depths can be calculated using the Xie Cai formula based on parameters such as the hydraulic radius R and the slope S of the channel. (where V is the average velocity and C is the Schertz coefficient) to estimate the flow velocity. By assuming a layered channel and combining the change in the hydraulic radius in the vertical direction, the flow velocity at different depths can be further estimated. However, this method has limited applicability to complex natural water bodies (such as rivers and lakes).

[0072] Of course, the situations in which the flow velocity of the same type of microplastic particles at different depths is obtained are not limited to the situations listed above. No matter what the situation is, as long as the flow velocity of different types of microplastic particles at different depths can be obtained, it will be sufficient.

[0073] In one embodiment, the process of obtaining the flow velocity of different types of microplastic particles at different depths based on a one-dimensional hydrodynamic model of a river includes: obtaining relevant data of the water body, the relevant data including: average cross-sectional flow velocity, friction flow velocity, and water body depth; based on the relevant data of the water body and the current depth of the microplastic particles in the water body, calculating the flow velocity of each type of microplastic particles at different depths.

[0074] In this embodiment, the flow velocity u(z) at different depths Z is obtained by using a one-dimensional hydrodynamic model of the river:

[0075]

[0076] Where: u(z) is the velocity at the point with depth z, m / s; u0 is the average velocity of the cross section, m / s; u * is the friction velocity, m / s; g is the acceleration due to gravity; J is the hydraulic gradient; k is the Karman constant.

[0077] Mass conservation equation and momentum balance equation:

[0078]

[0079] Where: x, t is the spatial coordinate and time coordinate respectively; B is the river width, m; q is the lateral inflow; Q is the cross-sectional flow, m 3 / s; A is the cross-sectional area of ​​water flow, m 2 ; u is the vertical distribution velocity, m / s; C is the Xie Cai coefficient, g is the acceleration due to gravity, m 2 / s; h is the water depth, m; R is the hydraulic radius.

[0080] Embodiment 2

[0081] The present invention also provides an electronic device. In an embodiment of a device according to the present invention, the device includes a processor and a storage device, the storage device can be configured to store a program for executing the microplastic motion trajectory prediction method of the above method embodiment, and the processor can be configured to execute the program in the storage device, which includes but is not limited to the program for executing the microplastic motion trajectory prediction method of the above method embodiment. For ease of explanation, only the parts related to the embodiment of the present invention are shown. For specific technical details not disclosed, please refer to the method part of the embodiment of the present invention. The control device can be a control device device formed by various electronic devices.

[0082] Embodiment 3

[0083] The present invention also provides a computer-readable storage medium. In a computer-readable storage medium embodiment according to the present invention, the computer-readable storage medium can be configured to store a program for executing the microplastic motion trajectory prediction method of the above-mentioned method embodiment, and the program can be loaded and run by the processor to implement the above-mentioned microplastic motion trajectory prediction method. For ease of explanation, only the parts related to the embodiment of the present invention are shown. For specific technical details not disclosed, please refer to the method part of the embodiment of the present invention. The computer-readable storage medium can be a storage device formed by various electronic devices. Optionally, the computer-readable storage medium in the embodiment of the present invention is a non-temporary computer-readable storage medium.

[0084] So far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it is easy for those skilled in the art to understand that the protection scope of the present invention is obviously not limited to these specific embodiments. Without departing from the principle of the present invention, those skilled in the art can make equivalent changes or substitutions to the original technical features, and the technical solutions after these changes or substitutions will fall within the protection scope of the present invention.

Claims

1. A method for predicting the movement trajectory of microplastics, characterized in that: include: Obtain the type of microplastic particles to be tested; The type of the microplastic particles to be tested is input into a trained river microplastic particle migration trajectory prediction model to obtain a prediction result, wherein the process of obtaining the trained river microplastic particle migration trajectory prediction model includes at least the following steps: obtaining the motion patterns of different types of microplastic particles; using a particle tracking method based on the motion patterns of different types of microplastic particles to obtain the motion trajectories of different types of microplastic particles in the water body.

2. The method according to claim 1, characterized in that Based on the movement laws of different types of microplastic particles, the particle tracking method is used to obtain the movement trajectories of different types of microplastic particles in the water body, which includes at least the following steps: Select an appropriate time step, and for each time step, use the particle displacement formula to calculate the horizontal and vertical displacements based on the type of microplastics and the movement law of microplastic particles; Based on the calculated horizontal and vertical displacements, the position of the microplastic particles is updated after each time step; As the time step continues to advance, the above displacement calculation and position update process is repeated to obtain multiple position points. All position points are connected in chronological order to obtain the complete movement trajectory of microplastic particles in the water body.

3. The method according to claim 2, characterized in that Based on the type of microplastics and the movement law of microplastic particles, the process of using the particle displacement formula to calculate the horizontal and vertical displacements includes: Based on the movement patterns of different types of microplastic particles, the horizontal migration speed and vertical sedimentation speed of different types of microplastic particles in water bodies are obtained; Based on the horizontal migration velocity and vertical sedimentation velocity of different types of microplastic particles in the water body, the horizontal and vertical displacements of the microplastic particles are obtained.

4. According to the method of claim 3, the process of obtaining the horizontal and vertical displacements of the microplastic particles based on the horizontal migration speed and vertical sedimentation speed of different types of microplastic particles in the water body comprises: Substitute the horizontal migration velocity and vertical sedimentation velocity of different types of microplastic particles in the water into the particle displacement formula to obtain the horizontal and vertical displacements of the microplastic particles; The method at least includes the following steps to obtain the particle displacement formula: the microplastic particles are regarded as the comprehensive result of horizontal and vertical motion, and a Lagrange particle tracking model is established; in the horizontal direction, the particle migration velocity in the water flow and the horizontal component of the random velocity caused by the turbulent effect are combined, and based on the turbulence theory, the random velocity part is expressed as a form related to the horizontal turbulent diffusion coefficient and the time step, and the deterministic horizontal migration velocity is considered at the same time, so as to derive the horizontal displacement equation; in the vertical direction, the sedimentation rate of the microplastics and the vertical random velocity caused by the turbulent effect are considered, and they are expressed as a form related to the vertical turbulent diffusion coefficient and the time step, and then combined with the turbulent diffusion coefficient expression, the vertical displacement equation is derived.

5. The method according to claim 3, characterized in that: Based on the movement laws of different types of microplastic particles, the process of obtaining the horizontal migration speed and vertical sedimentation speed of different types of microplastic particles in water bodies includes: Obtain the flow rate of different types of microplastic particles at different depths in the water column; Analyze the horizontal driving force and vertical force on different types of microplastic particles in water, and obtain the motion equations of different types of microplastic particles in water; The flow velocities obtained at different depths are substituted into the corresponding motion equations of different types of microplastic particles in the water body, and the horizontal migration velocity and vertical sedimentation velocity of each type of microplastic particles in the water body are calculated.

6. The method according to claim 5, characterized in that The process of obtaining the flow rate of different types of microplastic particles at different depths in the water column includes: Obtain the location and movement status of different types of microplastic particles in water bodies; The flow velocities at different depths are processed in layers, and the flow velocities of different types of microplastic particles at different depths are obtained based on the one-dimensional hydrodynamic model of the river.

7. The method according to claim 6, characterized in that The process of obtaining the flow velocity of different types of microplastic particles at different depths based on the one-dimensional hydrodynamic model of the river includes: Acquire relevant data of the water body, wherein the relevant data includes: average flow velocity of the cross section, friction flow velocity, and water body depth; Based on the relevant data of the water body and the current depth of the microplastic particles in the water body, the flow rate of each type of microplastic particles at different depths is calculated.

8. An electronic device comprising a processor and a storage device, the storage device being suitable for storing a plurality of program codes, characterized in that: The program code is suitable for being loaded and run by a processor to execute the microplastic movement trajectory prediction method according to any one of claims 1 to 7.

9. A computer-readable storage medium storing a plurality of program codes, characterized in that: The program code is suitable for being loaded and run by a processor to execute the microplastic movement trajectory prediction method according to any one of claims 1 to 7.

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