Simulation device and method for sediment-water body phosphorus distribution balance of shallow lake

Abstract

The invention belongs to the technical field of water environment protection research, and discloses a shallow lake sediment-water body phosphorus distribution balance simulation device and method, and the device comprises a cylinder container, an equivalent water depth adjusting water tank, a water circulation assembly, a hydrodynamic force disturbance assembly and a water body mixing assembly; the cylinder container and the equivalent water depth adjusting water tank are arranged side by side; the hydrodynamic disturbance assembly is arranged above the cylinder container; the water body mixing assembly is positioned above the equivalent water depth adjusting water tank; the cylinder container is communicated with the equivalent water depth adjusting water tank through the water circulation assembly; the method can be used for researching the response relation of the phosphorus equilibrium concentration of the water body to independent or collaborative change of three elements, namely the biological available phosphorus concentration of the columnar sediment, the sediment-water interface disturbance intensity and the water depth, and the research result is used for supporting the endogenous phosphorus load management of the shallow lake under the double constraints of the phosphorus concentration target of the water body and the physical condition of the lake.

Description

Technical Field

[0001] The present invention relates to the technical field of water environmental protection research, and particularly relates to a simulation device and method for the phosphorus distribution balance of "sediment-water body" in shallow lakes. Background Art

[0002] The release flux of phosphorus in the sediment of shallow lakes, that is, the internal phosphorus load, is the main phosphorus source for the increase in water body phosphorus concentration and algal proliferation in summer. Currently, there are many devices for simulating the release flux of internal phosphorus in lakes, which mainly consider the release flux or release potential of phosphorus in sediments under various environmental conditions such as interface disturbance, water temperature, and dissolved oxygen, but cannot simulate the response relationship of the equilibrium phosphorus concentration in the water body to the change of internal phosphorus load under actual lake conditions, and cannot be used to quantitatively evaluate the influence effect of internal phosphorus load on the phosphorus concentration in the actual lake water body.

[0003] The equilibrium phosphorus concentration in the water body of shallow lakes is the final equilibrium result of various biogeochemical processes between sediment and water body, and it is mainly affected by three aspects: external phosphorus load, hydrodynamic force, and water depth. The external phosphorus load determines the bioavailable concentration of phosphorus in the sediment. The higher the bioavailable phosphorus concentration in the sediment, the greater the internal phosphorus load and the higher the phosphorus concentration in the water body. The stronger the disturbance of the hydrodynamic force on the sediment-water interface, the greater the internal phosphorus load and the higher the phosphorus concentration in the water body. Under the same internal phosphorus load, the shallower the lake, the smaller the environmental capacity, and the greater the influence of the concentration effect on the phosphorus concentration in the water body, and the higher the phosphorus concentration in the water body, and vice versa. Therefore, the "sediment-water body" phosphorus distribution balance simulation experimental device must be able to simulate the dynamic changes of these three aspects in order to establish the "sediment-water body" phosphorus distribution balance relationship.

[0004] Although the existing indoor simulation experimental devices and methods can explore the regulatory effects of different sediment bioavailable phosphorus concentrations and interface disturbance intensities on the phosphorus release flux, it is difficult to effectively simulate the influence of the dynamic change of water depth in actual shallow lakes on the "sediment-water body" phosphorus distribution balance. In the conventional columnar sediment simulation experiment, the overlying water column usually only has a fixed water depth of dozens of centimeters, while the actual water depth of shallow lakes in the natural state often shows continuous fluctuations in the range of 0-10 meters, which makes the simulation system based on a static water column difficult to truly reflect the characteristics of material exchange at the sediment-water interface under different water depth conditions of actual lakes. At the same time, the existing methods are also difficult to accurately reflect the combined influence of the interaction between water depth change and hydrodynamic conditions on the phosphorus migration and distribution process. In addition, for the research on the "sediment-water body" phosphorus distribution balance, there is currently a lack of an experimental method system that can effectively integrate the combined effects of multiple environmental factors, resulting in the inability of the existing indoor simulation technology to solve the problem of the "sediment-water body" phosphorus distribution balance relationship in shallow lakes under the combined action of water depth and hydrodynamic force. Summary of the Invention

[0005] The object of the present invention is to provide a simulation device and method for the phosphorus distribution balance of "sediment - water body" in shallow lakes, so as to solve the problem in the prior art that the indoor simulation technology cannot solve the problem of the phosphorus distribution balance relationship of "sediment - water body" in shallow lakes under the individual change or the combined action of two factors, namely water depth and hydrodynamic force.

[0006] The object of the present invention can be achieved by the following technical solutions: A simulation device for the phosphorus distribution balance of "sediment - water body" in shallow lakes includes a columnar container, an equivalent water depth adjustment water tank, a water circulation component, a hydrodynamic disturbance component, and a water body mixing component; a water level scale line is provided on the columnar container; the columnar container and the equivalent water depth adjustment water tank are arranged side by side; the hydrodynamic disturbance component is arranged above the columnar container; the water body mixing component is located above the equivalent water depth adjustment water tank; the columnar container and the equivalent water depth adjustment water tank are interconnected through the water circulation component.

[0007] Preferably, an equivalent water depth scale is provided on the equivalent water depth adjustment water tank; Among them, the equivalent water depth = the added water volume of the water depth adjustment water tank / the cross - sectional area of the water column overlying the sediment, and the equivalent water depth is adjusted by changing the added water volume.

[0008] Preferably, the water circulation component includes a first peristaltic pump; a first connecting pump pipe is connected to the first peristaltic pump, and one end of the first connecting pump pipe extends into the water column overlying the sediment inside the columnar container, and the other end extends into the equivalent water depth adjustment water tank; the water circulation component further includes a second peristaltic pump; a second connecting pump pipe is connected to the second peristaltic pump, and one end of the second connecting pump pipe extends into the equivalent water depth adjustment water tank, and the other end extends into the water column overlying the sediment inside the columnar container.

[0009] Preferably, the first peristaltic pump pumps the fluid in the columnar container into the equivalent water depth adjustment water tank; the second peristaltic pump pumps the fluid in the equivalent water depth adjustment water tank into the columnar container.

[0010] Preferably, the hydrodynamic disturbance component includes a first support iron stand, which is located beside the columnar container and presents an L - shaped structure, and its upper part is directly above the columnar container; a first speed - regulating motor is fixedly arranged on the upper part of the first support iron stand; the output end of the first speed - regulating motor is connected to a first transmission shaft, and the lower end of the first transmission shaft extends into the columnar container; a first propeller is fixedly connected to the lower end of the first transmission shaft.

[0011] Preferably, the water mixing assembly includes a second supporting iron frame, which is located beside the equivalent water depth regulating water tank and has an L-shaped structure, with its upper part located directly above the equivalent water depth regulating water tank; a second speed regulating motor is fixedly arranged on the upper part of the second supporting iron frame; a second speed regulating motor is connected to the output end of the second speed regulating motor, and the lower end of the second transmission shaft extends into the interior of the equivalent water depth regulating water tank; a second propeller is fixedly connected to the lower end of the second transmission shaft; and a second propeller is fixedly connected to the lower end of the second propeller.

[0012] A method for simulating the phosphorus distribution balance of "sediment-water body" in a shallow lake, simulating the effect of water depth change on the phosphorus distribution balance of "sediment-water body", comprising the following steps: A100: First, load the columnar sediment sample collected in situ into the column container (from bottom to top, columnar sediment, sediment-water interface and overlying water column), then add artificial lake water to the overlying water column of the column container to the water level mark, and leave it for 5-7 days to form a stable sediment-water interface; A200: Add artificial lake water to the equivalent water depth adjustment tank to reach the equivalent water depth of the target lake, and mark the dynamic water surface line of the tank with a marker next to the equivalent water depth scale; A300: Start the second speed regulating motor and adjust the speed. The second propeller disturbs the water in the equivalent water depth regulating water tank to be in a completely mixed state. A400: Start the first peristaltic pump and the second peristaltic pump at the same time, and adjust the speed of the two peristaltic pumps to balance the inflow and outflow of the first connecting pump pipe and the second connecting pump pipe, so that the phosphorus in the water body in the sediment-water interface and the equivalent water depth adjustment tank is exchanged; A500: Start the first speed regulating motor 14 and adjust its speed to change the speed of the first propeller 12 to achieve the required hydrodynamic disturbance intensity and keep the whole device running stably. After the phosphorus distribution of "sediment-water body" reaches equilibrium, take samples from the water tank to analyze the concentrations of total phosphorus (TP) and active dissolved phosphorus (SRP) in the water body; A600: In step A200, add different volumes of artificial lake water to change the equivalent water depth of the lake, repeat steps A300 to A500, and analyze the response relationship of the "sediment-water body" phosphorus distribution balance to the change of water depth alone.

[0013] The simulation of the impact of the coordinated changes in water depth and hydrodynamics on the phosphorus distribution balance between sediments and water bodies includes the following steps: B100: First, load the columnar sediment sample collected in situ into the column container (from bottom to top, columnar sediment, sediment-water interface and overlying water column), then add artificial lake water to the overlying water column of the column container to the water level mark, and leave it for 5-7 days to form a stable sediment-water interface; B200: Add artificial lake water to the equivalent water depth adjustment tank to reach the equivalent water depth of the target lake, and mark the dynamic water surface line of the tank with a marker pen beside the equivalent water depth scale; B300: Start the second speed regulating motor and adjust its speed. The disturbing effect of the second propeller makes the water body in the equivalent water depth adjustment tank in a fully mixed state; B400: Start the first peristaltic pump and the second peristaltic pump simultaneously, and adjust the speeds of the two peristaltic pumps so that the water inflow and outflow of the first connecting pump pipe and the second connecting pump pipe reach balance, enabling the exchange of phosphorus between the sediment-water interface and the water body in the equivalent water depth adjustment tank; B500: Start the first speed regulating motor and adjust its speed to change the speed of the first propeller, thereby forming different hydrodynamic disturbance intensities, and keep the whole set of devices running continuously and stably. After the phosphorus distribution between "sediment-water body" reaches balance, sample the water body in the tank to analyze the concentrations of total phosphorus (TP) and soluble reactive phosphorus (SRP) in the water body, and analyze the quantitative response relationship between the phosphorus distribution balance of "sediment-water body" and the hydrodynamic disturbance intensity at a certain lake water depth condition; B600: Add different volumes of artificial lake water in step B200 to change the equivalent water depth of the lake, and repeat steps B300 and B500 to analyze the response relationship between the phosphorus distribution balance of "sediment-water body" and the separate change of hydrodynamic disturbance intensity and the change of hydrodynamic disturbance intensity in coordination with water depth.

[0014] Preferably, replace the columnar sediment samples in different lakes or different regions of the same lake to simulate the influence of sediment bioavailable phosphorus concentration on the phosphorus distribution balance of "sediment-water body".

[0015] Advantages of the present invention: The present invention can be used to study the response relationship of the equilibrium concentration of water body phosphorus to the separate or coordinated changes of three factors, namely, the bioavailable phosphorus concentration of columnar sediment, the disturbance intensity of the sediment-water interface, and the water depth. The research results are used to support the management of endogenous phosphorus load in shallow lakes under the dual constraints of water body phosphorus concentration target and lake physical conditions. In addition, the water column depth of the traditional columnar simulation device is usually limited within a range of dozens of centimeters and cannot simulate the actual lake water depth and its changes. Moreover, the technical operation of the present invention is simple and the analysis method is reliable, and it is expected to be widely applied in the management of endogenous phosphorus load in shallow lakes. Description of the drawings

[0016] The present invention will be further described below with reference to the drawings.

[0017] Figure 1 is the overall structural schematic diagram of the present invention; Figure 2 is the plan view of the overall structure in the present invention; Figure 3It is the experimental data graph of Experiment 1 in the present invention; Figure 4 It is the experimental data graph of Experiment 2 in the present invention; Figure 5 It is the experimental data graph of Experiment 3 in the present invention; In the figure: 1. Columnar sediment; 2. Sediment-water interface; 3. Column container; 4. Water level scale line; 5. Equivalent water depth adjustment water tank; 6. Equivalent water depth scale; 7. Dynamic water surface line of the water tank; 8. First peristaltic pump; 9. First connecting pump pipe; 10. Second peristaltic pump; 11. Second connecting pump pipe; 12. First propeller; 13. First transmission shaft; 14. First speed regulating motor; 15. First supporting iron stand; 16. Second propeller; 17. Second transmission shaft; 18. Second speed regulating motor; 19. Second supporting iron stand. Detailed implementation manners

[0018] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0019] Please refer to Figure 1 - Figure 2 As shown, a simulation device for the phosphorus distribution balance of "sediment-water body" in a shallow lake includes a column container 3, an equivalent water depth adjustment water tank 5, a water circulation component, a hydrodynamic disturbance component, and a water body mixing component; a water level scale line 4 is provided on the column container 3.

[0020] The column container 3 and the equivalent water depth adjustment water tank 5 are arranged side by side; the hydrodynamic disturbance component is arranged above the column container 3; the water body mixing component is located above the equivalent water depth adjustment water tank 5; the column container 3 and the equivalent water depth adjustment water tank 5 are interconnected through the water circulation component.

[0021] The column container 3 is used to collect in-situ sediment samples.

[0022] The equivalent water depth adjustment water tank 5 is used to simulate the dilution or concentration effect of the change in the water depth of the shallow lake on the internal phosphorus load. The material of the equivalent water depth adjustment water tank 5 is plexiglass; an equivalent water depth scale 6 is provided on the equivalent water depth adjustment water tank 5; the equivalent water depth adjustment water tank 5 is connected to the connecting pipeline of the water circulation component, and the equivalent water depth = the added water volume of the water depth adjustment water tank / the cross-sectional area of the water column overlying the sediment. The equivalent water depth can be adjusted by changing the added water volume (the equivalent water depth is marked by the water level scale line 4, that is, the water level height position).

[0023] The water cycle component is mainly used to simulate the endogenous phosphorus load flux at the sediment-water interface 2 and the phosphorus exchange in the lake water body, so as to achieve the phosphorus distribution equilibrium state of "sediment-water body". The water cycle component includes a first peristaltic pump 8; a first connecting pump pipe 9 is connected to the first peristaltic pump 8. One end of the first connecting pump pipe 9 extends into the overlying water column inside the columnar container 3, and the other end extends into the equivalent water depth adjustment water tank 5. The fluid flow direction is: from the columnar container 3 to the equivalent water depth adjustment water tank 5; the water cycle component further includes a second peristaltic pump 10; a second connecting pump pipe 11 is connected to the second peristaltic pump 10. One end of the second connecting pump pipe 11 extends into the equivalent water depth adjustment water tank 5, and the other end extends into the overlying water column inside the columnar container 3. The fluid flow direction is: from the equivalent water depth adjustment water tank 5 to the columnar container 3.

[0024] The hydrodynamic disturbance component is used to simulate the influence of the hydrodynamic force of a shallow lake on the endogenous phosphorus load at the sediment-water interface 2. The hydrodynamic disturbance component includes a first support iron stand 15, which is located beside the columnar container 3 and presents an L-shaped structure, and its upper part is directly above the columnar container 3; a first speed-regulating motor 14 is fixedly arranged on the upper part of the first support iron stand 15; the output end of the first speed-regulating motor 14 is connected to a first transmission shaft 13, and the lower end of the first transmission shaft 13 extends into the columnar container 3; a first propeller 12 is fixedly connected to the lower end of the first transmission shaft 13, and the first propeller 12 is used to disturb the sediment sample inside the columnar container 3.

[0025] The water body mixing component is used to simulate the complete mixing state of the water body in a shallow lake. The water body mixing component includes a second support iron stand 19, which is located beside the equivalent water depth adjustment water tank 5 and presents an L-shaped structure, and its upper part is directly above the equivalent water depth adjustment water tank 5; a second speed-regulating motor 18 is fixedly arranged on the upper part of the second support iron stand 19; the output end of the second speed-regulating motor 18 is connected to a second transmission shaft 17, and the lower end of the second transmission shaft 17 extends into the equivalent water depth adjustment water tank 5; a second propeller 16 is fixedly connected to the lower end of the second transmission shaft 17; a second propeller 16 is fixedly connected to the lower end of the second propeller 16, and the second propeller 16 is used to quickly mix the substances inside the water tank.

[0026] A simulation experiment device for the phosphorus distribution balance of "sediment-water body" in a shallow lake, and an experimental and experimental result analysis method matched with it, including two experimental methods, as follows: Simulating the influence of water depth change on the phosphorus distribution balance of "sediment-water body", including the following steps: A100: First, load a sample of columnar sediment 1 collected in situ (from bottom to top are columnar sediment 1, sediment-water interface 2, and overlying water column) inside the cylindrical container 3. Then, add artificial lake water to the overlying water column of the cylindrical container 3 up to the water level scale line 4, and let it stand for 5 - 7 days to form a stable sediment-water interface 2.

[0027] A200: Add artificial lake water to the equivalent water depth adjustment water tank 5 to reach the equivalent water depth of the target lake, and mark the dynamic water surface line 7 of the water tank with a marker pen next to the equivalent water depth scale 6.

[0028] A300: Start the second speed control motor 18 and adjust its speed. The disturbing action of the second propeller 16 makes the water body in the equivalent water depth adjustment water tank 5 in a fully mixed state.

[0029] A400: At the same time, start the first peristaltic pump 8 and the second peristaltic pump 10, and adjust the speeds of the two peristaltic pumps so that the water inflow and outflow of the first connecting pump pipe 9 and the second connecting pump pipe 11 reach balance, enabling the exchange of phosphorus between the sediment-water interface 2 and the water body in the equivalent water depth adjustment water tank 5.

[0030] A500: Start the first speed control motor 14 and adjust its speed to change the speed of the first propeller 12 to reach the required hydrodynamic disturbance intensity, and keep the whole set of devices running continuously and stably. After the phosphorus distribution in the "sediment-water body" reaches balance, take samples from the water tank to analyze the concentrations of total phosphorus (TP) and soluble reactive phosphorus (SRP) in the water body.

[0031] A600: Add different volumes of artificial lake water in step A200 to change the equivalent water depth of the lake, and repeat steps A300 to A500 to analyze the response relationship of the phosphorus distribution balance in the "sediment-water body" to the independent change of water depth.

[0032] Simulating the influence of the coordinated change of water depth and hydrodynamic force on the phosphorus distribution balance in the "sediment-water body" includes the following steps: B100: First, load a sample of columnar sediment 1 collected in situ (from bottom to top are columnar sediment 1, sediment-water interface 2, and overlying water column) inside the cylindrical container 3. Then, add artificial lake water to the overlying water column of the cylindrical container 3 up to the water level scale line 4, and let it stand for 5 - 7 days to form a stable sediment-water interface 2.

[0033] B200: Add artificial lake water to the equivalent water depth adjustment water tank 5 to reach the equivalent water depth of the target lake, and mark the dynamic water surface line 7 of the water tank with a marker pen next to the equivalent water depth scale 6.

[0034] B300: Start the second speed control motor 18 and adjust its speed. The disturbing action of the second propeller 16 makes the water body in the equivalent water depth adjustment water tank 5 in a fully mixed state.

[0035] B400: Start the first peristaltic pump 8 and the second peristaltic pump 10 simultaneously, and adjust the rotational speeds of the two peristaltic pumps so that the water inflow and outflow of the first connecting pump tube 9 and the second connecting pump tube 11 reach equilibrium, enabling the exchange of phosphorus in the water body between the sediment-water interface 2 and the equivalent water depth adjustment water tank 5.

[0036] B500: Start the first speed-regulating motor 14 and adjust its rotational speed to change the rotational speed of the first propeller 12, thereby forming different hydrodynamic disturbance intensities, and maintaining the continuous and stable operation of the entire device. After the "sediment-water body" phosphorus distribution reaches equilibrium, take samples from the water tank to analyze the concentrations of total phosphorus (TP) and soluble reactive phosphorus (SRP) in the water body, and analyze the quantitative response relationship between the "sediment-water body" phosphorus distribution equilibrium and the hydrodynamic disturbance intensity at the sediment-water interface 2 under certain lake water depth conditions.

[0037] B600: Add different volumes of artificial lake water in step B200 to change the equivalent water depth of the lake, repeat step B300 and step B500, and analyze the response relationships of the "sediment-water body" phosphorus distribution equilibrium to the individual change of the hydrodynamic disturbance intensity and the change of the water depth in cooperation with the hydrodynamic disturbance intensity.

[0038] It should be noted here that: the chemical components of the artificial lake water are similar to those of natural lake water. By replacing the columnar samples of different lakes or different regions of the same lake, the influence of the sediment bioavailable phosphorus concentration on the "sediment-water body" phosphorus distribution equilibrium is simulated.

[0039] The simulation experimental device and method provided by the present invention can be used to study the response relationships of the equilibrium concentration of water body phosphorus to the individual or cooperative changes of three factors, namely, the bioavailable phosphorus concentration of columnar sediment 1, the disturbance intensity at the sediment-water interface 2, and the water depth. The research results are used to support the management of the internal phosphorus load in shallow lakes under the dual constraints of the water body phosphorus concentration target and the lake physical conditions. The depth of the overlying water column of the traditional columnar simulation device is usually limited within a range of dozens of centimeters and cannot simulate the actual lake water depth and its changes. In addition, the technical operation of the present invention is simple and the analysis method is reliable, and it is expected to be widely applied in the management of the internal phosphorus load in shallow lakes.

[0040] When the simulation experimental device provided by the present invention is actually working, the following methods can be used to replace variables to study the influence of the bioavailable phosphorus concentration on the "sediment-water body" phosphorus distribution equilibrium in shallow lakes: I. When the simulation experimental device provided by the present invention is actually working, different lake sediment samples or sediment samples from different regions of the same lake may have different bioavailable phosphorus concentrations. Therefore, the influence of the bioavailable phosphorus concentration on the "sediment-water body" phosphorus distribution equilibrium in shallow lakes can be studied by replacing the columnar sediment 1 samples.

[0041] Second, when the simulation experiment device provided by the present invention is actually working, the in-situ columnar sediment 1 sample collected is directly used as the columnar sediment 1 in the column container 3, maintaining the in-situ state of the columnar sediment 1 sample. For example: In a certain shallow lake, a columnar sediment sampler is used to collect a columnar sediment sample with a depth of 10 cm and a diameter of 10 cm for simulation experiment research.

[0042] Third, when the simulation experiment device provided by the present invention is actually working, the water depth is changed by adjusting the water addition volume of the equivalent water depth adjustment water tank 5 to simulate the influence of water depth on the phosphorus distribution balance of the "sediment-water body" in the shallow lake. The equivalent water depth can be arbitrarily adjusted within the water depth range of the shallow lake (generally, the water depth of the shallow lake is below 10 m) according to the volume of the water tank. For example: The equivalent water depth adjustment water tank 5 is made of transparent organic glass, with specifications of length × width × height of 60 cm × 35 cm × 40 cm, and the volume V is 105000 cm 3 , and its maximum adjustable water depth is H = V / S = 1070 cm = 10.7 m.

[0043] Fourth, when the simulation experiment device provided by the present invention is actually working, the rotation speed of the first propeller 12 is changed by adjusting the first speed regulating motor 14, thereby changing the hydraulic disturbance intensity of the sediment-water interface 2 to simulate its influence on the "sediment-water body phosphorus" distribution balance. For example: The hydraulic disturbance intensity is represented by the flow velocity gradient G value, which reflects the degree of water flow turbulence and the magnitude of shear force. In the above example of the columnar sediment 1 sample, when the depth of the water level scale line 4 of the column container 3 from the sediment-water interface 2 is maintained at 10 cm, the G value changes in the range of 0 - 50 s -1 , which can cause a series of different states of the sediment-water interface 2, such as no disturbance, disturbance but the surface sediment does not suspend, the surface sediment slightly suspends, and the surface sediment violently suspends.

[0044] It should be noted here that: The G value refers to the change rate of the water flow velocity in the direction perpendicular to the water flow direction per unit time, and the unit is s -1 .

[0045] Fifth, when the simulation experiment device provided by the present invention is actually working, the rotation speed of the second propeller 16 is changed by adjusting the second speed regulating motor 18 to quickly mix the substances in the water tank evenly, thereby simulating the mixing state of the water body in the shallow lake. For example: When the G value is adjusted > 50 s -1 , the water body in the water tank can be violently mixed and the goal of no sedimentation of suspended substances can be achieved.

[0046] VI. When the simulation experiment device provided by the present invention is actually working, the first peristaltic pump 8 and the second peristaltic pump 10 maintain the same rotation speed. When the first connecting pump tube 9 and the second connecting pump tube 11 have the same specifications, the water inflow and outflow rates of the sediment equivalent water depth adjustment water tank 5 are equal, simulating the phosphorus exchange between the sediment-water interface 2 and the lake water body.

[0047] Experiment 1, hydrodynamic disturbance intensity experiment: Collect a columnar sediment sample 1 from a certain shallow lake. The cross-sectional diameter of the columnar sediment 1 is 10 cm, and the equivalent water depth of the lake is fixed at 0.5 m. Set 5 groups of hydrodynamic disturbance intensities within the range of G value from 0 to 50 s -1 to enable multiple state changes of the sediment-water interface 2 from static (undisturbed) to the state where the sediment-water interface 2 is eroded and suspended by water power. After reaching the equilibrium state within 48 hours, analyze the changes in the concentrations of soluble reactive phosphorus (SRP) and total phosphorus (TP) in the water body of the equivalent water depth adjustment water tank 5.

[0048] The equilibrium concentration of phosphorus in the simulated lake water body (equivalent water depth adjustment water tank 5) is as Figure 3 shown.

[0049] It can be seen from Figure 3 that the equilibrium concentrations of SRP and TP increase with the increase in the hydrodynamic disturbance intensity of the sediment-water interface 2. The equilibrium concentration of TP increases from 0.05 mg / L when G value = 0 s -1 to 0.62 mg / L when G value = 47 s -1 . Among them, the equilibrium concentration of SRP increases from 0.05 mg / L when G value = 0 s -1 to 0.58 mg / L when G value = 47 s -1 . The increase in the equilibrium concentration of TP is mainly contributed by SRP.

[0050] To sum up, the above embodiments of the present invention simulate the law of the equilibrium concentration of water body phosphorus and its change with the disturbance intensity under the condition of fixed lake water depth, and can be used to quantitatively analyze the influence effect of the hydrodynamic disturbance intensity of the sediment-water interface 2 in a shallow lake on the equilibrium concentration of water body phosphorus, and can be applied to the scenario simulation of various disturbance intensities of the sediment-water interface 2 in a specific shallow lake.

[0051] Experiment 2, water depth change experiment: Collect a columnar sediment sample 1 from a certain shallow lake. The cross-sectional diameter of the columnar sediment 1 is 10 cm, and the G value is fixed at 20 s -1 (the sediment-water interface 2 is disturbed but there is no sediment suspension). Set 7 groups of water depth gradients within the range of 0.1 - 8 m water depth. After reaching the equilibrium state within 48 hours, analyze the change in the concentration of soluble reactive phosphorus (SRP) in the water body of the equivalent water depth adjustment water tank 5.

[0052] The phosphorus equilibrium concentration of the simulated lake water body (equivalent water depth adjustment water tank 5) is as follows Figure 4 shown.

[0053] As Figure 4 can be seen, the SRP equilibrium concentration gradually decreases with the increase of water depth, decreasing from 0.15 mg / L at a water depth of 0.1 m to 0.03 mg / L at a water depth of 8 m, reflecting the dilution effect of the increase in water depth on the equilibrium phosphorus concentration in the water body. However, when the water depth increases by 80 times, the SRP equilibrium concentration in the water body decreases by 5 times, which reflects the buffering effect of the sediment on the decrease of the phosphorus concentration in the water body, that is, as the phosphorus concentration in the water body decreases, more sediment phosphorus is distributed into the water body, compensating for part of the decrease in the phosphorus concentration in the water body.

[0054] Experiment 3: Experiment on the change of water depth in coordination with the intensity of hydrodynamic disturbance: Collect a columnar sediment sample 1 from a shallow lake. The cross-sectional diameter of the columnar sediment 1 is 10 cm (the same as in Experiment 2). Change the G value from 20 s -1 to 10 s -1 (the sediment-water interface 2 is disturbed but no sediment is suspended). Set 7 groups of water depth gradients in the water depth range of 0.1 - 8 m. After reaching the equilibrium state within 48 hours, analyze the change of the dissolved reactive phosphorus (SRP) concentration in the water body of the equivalent water depth adjustment water tank 5, and compare it with the results of Experiment 2 when the G value is 20 s -1 to analyze the influence of the water depth in coordination with the intensity of hydrodynamic disturbance on the SRP equilibrium concentration.

[0055] The comparison results of the phosphorus equilibrium concentration of the simulated lake water body (equivalent water depth adjustment water tank 5) between Experiment 3 and Experiment 2 are as follows Figure 5 shown.

[0056] As Figure 5 can be seen, when the G value changes from 20 s -1 to 10 s -1 , the SRP equilibrium concentration also gradually decreases with the increase of water depth, decreasing from 0.057 mg / L at a water depth of 0.1 m to 0.009 mg / L at a water depth of 8 m, reflecting the dilution effect of the increase in water depth on the equilibrium phosphorus concentration in the water body. However, when the water depth increases by 80 times, the SRP equilibrium concentration in the water body decreases by 6 times, which also reflects the buffering effect of the sediment on the decrease of the phosphorus concentration in the water body. When the G value is 20 s -1 , the SRP equilibrium concentration is about 3.5 times that when the G value is 10 s -1 . The results of this experiment reflect the influence of the change of water depth in coordination with hydrodynamic on the phosphorus distribution balance of "sediment-water body".

[0057] In summary, the above embodiments of the present invention simulate the phosphorus equilibrium concentration in the water body of lakes with various water depths and its variation law with water depth under fixed and changed hydrodynamic disturbance intensities at the sediment-water interface 2, and can be used to quantitatively analyze the influence of water depth and hydrodynamic changes on the phosphorus equilibrium concentration in the water body of shallow lake groups. The research results can be used to guide the classified management of endogenous phosphorus loads in lakes with different water depths.

[0058] As can be seen from Experiment 1, Experiment 2, and Experiment 3, the present invention can simulate the influence of the hydrodynamic disturbance intensity at the sediment-water interface 2, the individual change of water depth, or the combined change of both on the phosphorus equilibrium concentration in the water body. In addition, experiments can also be carried out with column samples from different lakes to study the influence of the bioavailable phosphorus concentration in the sediment on the phosphorus equilibrium concentration in the water body. Therefore, the experimental results can be used to support the management of endogenous phosphorus loads in shallow lakes under the dual constraints of the phosphorus concentration target in the water body and the physical conditions of the lakes.

[0059] It should be noted that in this article, terms such as "including", "comprising", or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article, or device including a series of elements not only includes those elements but also includes other elements not explicitly listed, or further includes elements inherent to such a process, method, article, or device.

[0060] Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention.

Claims

1. A simulation device for the phosphorus distribution balance of "sediment-water body" in shallow lakes, characterized in that: It includes a cylindrical container (3), an equivalent water depth adjustment water tank (5), a water circulation component, a hydrodynamic disturbance component, and a water body mixing component; The hydrodynamic disturbance component is arranged above the cylindrical container (3) and is used to simulate the influence of the hydrodynamic force of a shallow lake on the internal phosphorus load of the sediment-water interface (2); The water body mixing component is located above the equivalent water depth adjustment water tank (5) and is used to simulate the complete mixing state of the water body in a shallow lake; The cylindrical container (3) and the equivalent water depth adjustment water tank (5) are interconnected through the water circulation component.

2. The simulation device for the phosphorus distribution balance of "sediment-water body" in a shallow lake according to claim 1, wherein: An equivalent water depth scale (6) is provided on the equivalent water depth adjustment water tank (5); A water level scale line (4) is provided on the cylindrical container (3); the cylindrical container (3) and the equivalent water depth adjustment water tank (5) are arranged side by side; Among them, the equivalent water depth = the volume of water added to the equivalent water depth adjustment water tank / the cross-sectional area of the water column overlying the sediment, and the equivalent water depth is adjusted by changing the volume of added water.

3. The simulation device for phosphorus distribution balance of "sediment - water body" in a shallow lake according to claim 1, wherein: One end of a first connecting pump pipe (9) is connected to the first peristaltic pump (8) of the water circulation component, and one end of this first connecting pump pipe (9) extends into the water column covering the inside of the cylindrical container (3), and the other end extends into the inside of the equivalent water depth adjustment water tank (5); One end of a second connecting pump pipe (11) is connected to the second peristaltic pump (10) of the water circulation component, and one end of this second connecting pump pipe (11) extends into the inside of the equivalent water depth adjustment water tank (5), and the other end extends into the water column covering the inside of the cylindrical container (3).

4. A simulation device for the phosphorus distribution balance of "sediment-water body" in a shallow lake according to claim 3, characterized in that: The first peristaltic pump (8) pumps the fluid in the cylindrical container (3) into the equivalent water depth adjustment water tank (5); the second peristaltic pump (10) pumps the fluid in the equivalent water depth adjustment water tank (5) into the cylindrical container (3).

5. A simulation device for the phosphorus distribution balance of "sediment - water body" in a shallow lake according to claim 1, characterized in that: The first support iron stand (15) of the hydrodynamic disturbance component is located beside the cylindrical container (3) and presents an L-shaped structure, and its upper part is directly above the cylindrical container (3); A first speed-regulating motor (14) is fixedly arranged on the upper part of the first support iron stand (15); the output end of the first speed-regulating motor (14) is connected to a first transmission shaft (13), and the lower end of this first transmission shaft (13) extends into the inside of the cylindrical container (3); a first propeller (12) is fixedly connected to the lower end of the first transmission shaft (13).

6. A simulation device for the phosphorus distribution balance of "sediment-water body" in a shallow lake according to claim 1, characterized in that: The second support iron stand (19) of the water body mixing component is located beside the equivalent water depth adjustment water tank (5) and presents an L-shaped structure, and its upper part is directly above the equivalent water depth adjustment water tank (5); A second speed-regulating motor (18) is fixedly arranged on the upper part of the second support iron stand (19); the output end of the second speed-regulating motor (18) is connected to a second transmission shaft (17), and the lower end of this second transmission shaft (17) extends into the inside of the equivalent water depth adjustment water tank (5); a second propeller (16) is fixedly connected to the lower end of the second transmission shaft (17); a second propeller (16) is fixedly connected to the lower end of the second propeller (16).

7. A simulation method for the phosphorus distribution balance of "sediment-water body" in a shallow lake, applicable to the simulation device for the phosphorus distribution balance of "sediment-water body" in a shallow lake described in any one of claims 1-6, characterized in that: This simulation method is used to simulate the influence of water depth change on the phosphorus distribution balance of "sediment-water body".

8. A simulation method for the phosphorus distribution balance of "sediment-water body" in shallow lakes according to claim 7, characterized in that: This method includes the following steps: A100: First, load a sample of columnar sediment (1) collected in situ inside the columnar container (3). Then, add artificial lake water to the overlying water column of the columnar container (3) up to the water level scale line (4), and let it stand for 5 - 7 days to form a stable sediment - water interface (2). A200: Add artificial lake water to the equivalent water depth adjustment water tank (5) to reach the equivalent water depth of the target lake. Mark the dynamic water surface line (7) of the water tank with a marker pen next to the equivalent water depth scale (6). A300: Start the second speed - regulating motor (18) and adjust its speed. The disturbing effect of the second propeller (16) makes the water body in the equivalent water depth adjustment water tank (5) in a fully mixed state. A400: At the same time, start the first peristaltic pump (8) and the second peristaltic pump (10), and adjust the speeds of the two peristaltic pumps so that the water inflow and outflow of the first connecting pump tube (9) and the second connecting pump tube (11) reach balance, enabling the exchange of phosphorus between the sediment - water interface (2) and the water body in the equivalent water depth adjustment water tank (5). A500: Start the first speed - regulating motor (14) and adjust its speed to change the speed of the first propeller (12), so that it operates at the required hydrodynamic disturbance intensity. A600: Let the device operate stably for two days to achieve the balance of "sediment - water body" phosphorus exchange. Collect water samples from the equivalent water depth adjustment water tank (5) and analyze their total phosphorus and active dissolved phosphorus concentrations. A700: In step A200, add different volumes of artificial lake water to change the equivalent water depth of the lake, and repeat steps A300 to A600 to analyze the response relationship of the "sediment - water body" phosphorus distribution balance to the independent change of water depth.

9. A simulation method for the phosphorus distribution balance of "sediment - water body" in a shallow lake, applicable to the simulation device for the phosphorus distribution balance of "sediment - water body" in a shallow lake described in any one of claims 1 - 6, characterized in that: This simulation method is used to simulate the influence of the coordinated changes of water depth and hydrodynamic on the "sediment - water body" phosphorus distribution balance.

10. A simulation method for the phosphorus distribution balance of "sediment-water body" in a shallow lake according to claim 9, characterized in that: This method includes the following steps: B100: First, load a sample of columnar sediment (1) collected in situ inside the columnar container (3). Then, add artificial lake water to the overlying water column of the columnar container (3) up to the water level scale line (4), and let it stand for 5 - 7 days to form a stable sediment - water interface (2). B200: Add artificial lake water to the equivalent water depth adjustment water tank (5) to reach the equivalent water depth of the target lake. Mark the dynamic water surface line (7) of the water tank with a marker pen next to the equivalent water depth scale (6). B300: Start the second speed - regulating motor (18) and adjust its speed. The disturbing effect of the second propeller (16) makes the water body in the equivalent water depth adjustment water tank (5) in a fully mixed state. B400: At the same time, start the first peristaltic pump (8) and the second peristaltic pump (10), and adjust the speeds of the two peristaltic pumps so that the water inflow and outflow of the first connecting pump tube (9) and the second connecting pump tube (11) reach balance, enabling the exchange of phosphorus between the sediment - water interface (2) and the water body in the equivalent water depth adjustment water tank (5). B500: Start the first speed - regulating motor (14) and adjust its speed to change the speed of the first propeller (12), thereby forming different hydrodynamic disturbance intensities. B600: The device operates stably for two days at each hydrodynamic disturbance intensity to achieve equilibrium in the phosphorus exchange between the "sediment-water body". Water samples are collected from the equivalent water depth adjustment tank (5) to analyze their total phosphorus and active dissolved phosphorus concentrations, and to analyze the response relationship of the phosphorus equilibrium concentration in the "sediment-water body" at a fixed water depth to the change in hydrodynamic disturbance intensity. B700: In step B200, different volumes of artificial lake water are added to change the equivalent water depth of the lake. Steps B300 to B600 are repeated to analyze the response relationships of the phosphorus distribution equilibrium in the "sediment-water body" to the individual change in hydrodynamic disturbance intensity and the combined change in water depth and hydrodynamic disturbance intensity.

Images