A method for constructing a total purification model of pollutants in seawater by intertidal zones and its application

Abstract

The present invention discloses a construction method and application of a total purification model of pollutants in seawater by the intertidal zone, belonging to the field of hydrological environment technology. The construction method of the model includes the following steps: establishing an ecological sub-circulation system; determining the variables that cause pollutant changes in the intertidal zone; expressing the influence of each variable on the pollutant with a formula; determining the amount of change of pollutants caused by each variable; obtaining the migration equation of the purification of pollutants in seawater by the intertidal zone; and obtaining the total purification model of pollutants in seawater by the intertidal zone. The constructed model can be applied to calculate the purification amount and purification flux of pollutants in seawater by the intertidal zone; it can be applied to establish a purification model of a certain pollutant in seawater by the intertidal zone, and calculate the purification amount and purification flux of a certain pollutant in seawater by the intertidal zone. The present invention solves the problem that the prior art lacks a water quality purification model for the intertidal zone, and can also conduct a relatively comprehensive and in-depth study of the purification of pollutants entering seawater by intertidal wetlands.

Description

Technical Field

[0001] The present invention mainly relates to the field of hydrological environment technology, and specifically to a method for constructing a total purification model of pollutants in seawater in an intertidal zone and its application. Background Art

[0002] From an academic point of view, it is very difficult to solve environmental problems. This complexity stems from the diversity of causes. For example, the scope of various factors such as biology, chemistry, and physics is too wide, the available data that meets the model is seriously lacking, and the cost of data acquisition is high. Using appropriate mathematical methods and simplified mathematical models, many difficulties can often be overcome, and reliable answers or feasible solutions can be given at a certain level of accuracy (Peng Zezhou et al., 2007). At present, there are few studies on the purification of pollutants in intertidal wetlands entering seawater (from sea to land), and there is no water quality purification model for intertidal zones. For the existing models, there are problems such as the difficulty in obtaining available data that meets the model, and the applicability is not high. Summary of the invention

[0003] The technical solution of the present invention aims at the technical problem that the existing technical solutions are too single, and provides a solution that is significantly different from the existing technology. It mainly provides a method for constructing and applying a total purification model of pollutants in seawater in the intertidal zone, so as to solve the technical problem that the existing technology mentioned in the above background technology lacks a water quality purification model for the intertidal zone and cannot conduct in-depth research on the purification of pollutants entering the seawater in the intertidal zone.

[0004] The technical solution adopted by the present invention to solve the above technical problems is:

[0005] A method for constructing a total purification model of pollutants in seawater in an intertidal zone comprises the following steps:

[0006] S1. Consider various factors affecting the migration and transformation of pollutants in the intertidal zone, quantify them scientifically, and establish an ecological sub-circulation system of pollutants in the intertidal zone;

[0007] S2. Based on the ecological sub-circulation system of step S1, analyze the response relationship process of each subsystem to pollutants in the water and determine the variables that cause pollutant changes in the intertidal zone;

[0008] S3, using a formula to express the effect of each variable in step S2 on the pollutant;

[0009] S4. The concentration of pollutants in water is recorded as C, mg·L -1 , based on the formula in step S3, the amount of pollutant purification is analyzed in the time period (t, t+dt), and the amount of pollutant change caused by each variable in the time period dt is determined;

[0010] S5. Classify the changes in pollutants caused by each variable into items for purifying pollutants and items for inputting pollutants. Then, subtract the items for purifying pollutants from the items for inputting pollutants to obtain the migration equation for the purification of pollutants in seawater by the intertidal zone. The positive and negative values ​​of the results can indicate the purification effect of the intertidal zone on pollutants in seawater. When the result is a negative value, it means that the intertidal zone does not purify pollutants in seawater; when the result is a positive value, it means that the intertidal zone purifies pollutants in seawater.

[0011] S6. Based on the migration equation in step S5 and the value of pollutant concentration at the initial time, a total purification model of pollutants in seawater in the intertidal zone is obtained.

[0012] Furthermore, in step S2, 11 variables were determined, namely: atmospheric deposition, photolysis process, volatilization process, plant absorption or degradation, animal absorption or release, sedimentation process, resuspension process, sediment adsorption, suspended matter adsorption, sediment desorption or release, and microbial action.

[0013] Furthermore, in step S4, the changes in pollutants caused by various variables in the time period dt are respectively:

[0014] ①The change in pollutants caused by atmospheric deposition is D| t dt;

[0015] ②The change in pollutants caused by photolysis is K L ·C| t dt;K L is the photolysis rate coefficient; C is the pollutant concentration;

[0016] ③The change in pollutants caused by volatilization is K V ·C| t dt;K V is the volatility coefficient;

[0017] ④The change in pollutants caused by plants is (G P -D P )·P·A PP | t dt; A PP G is the coefficient of pollutants in plants; P , D P are plant growth rate and mortality rate, respectively; P is the concentration of phytoplankton;

[0018] ⑤The change in pollutants caused by animals is (C Z -R Z )·Z·A Z | t dt;C Z , R Zare animal predation rate and mortality rate respectively; Z is the concentration of animals in the water; A Z is the coefficient of animal contaminants;

[0019] ⑥The change caused by sedimentation is K s ·C1| t dt;K s is the sedimentation velocity; C1 is the concentration of particulate pollutants in water;

[0020] ⑦The change caused by resuspension is K r ·C2| t dt;K r is the resuspension coefficient; C2 is the pollutant concentration in the sediment;

[0021] ⑧The change caused by sediment adsorption is K0·(C2-C)| t dt; K0 is the adsorption coefficient between sediment and water;

[0022] ⑨The change caused by the adsorption of suspended matter is K1·(C1-C)| t dt; K1 is the adsorption coefficient between suspended matter and water;

[0023] ⑩The change caused by desorption is K d ·(C2-C)| t dt;K d is the desorption coefficient of sediment;

[0024] The change in pollutants caused by microorganisms is I w | t dt.

[0025] Further, in step S5, the migration equation is:

[0026]

[0027] Furthermore, in step S6, the pollutant concentration at the initial time is recorded as C0, and the total purification model of pollutants in the intertidal zone to seawater is:

[0028]

[0029] As an application of the above-mentioned intertidal zone purification model of pollutants in seawater, the present invention provides a method for calculating the purification flux of pollutants in seawater by the intertidal zone. Based on the total purification model of pollutants in seawater by the intertidal zone constructed according to the above content, the purification amount and purification flux of pollutants in seawater by the intertidal zone are calculated; specifically:

[0030] Equation (1-12) is a first-order linear non-homogeneous ordinary differential equation. Equation (1-12) can be rewritten as follows:

[0031]

[0032] Using the general solution formula of the first-order linear nonhomogeneous ordinary differential equation, the general solution of equation (1-12) is:

[0033]

[0034] Formula (1-14) uses the initial conditions in model (1-13), and the solution of model (1-13) is:

[0035]

[0036] That is, the amount of pollutants in seawater that are purified by the intertidal zone;

[0037] Based on the purification capacity of pollutants in seawater by the intertidal zone, the purification flux of pollutants in seawater by the intertidal zone is calculated using the following formula:

[0038]

[0039] Where C is the amount of pollutant purification, mg·L -1 ; Q is the purification flux, mg·m -2 ; v is the flow of seawater into the intertidal zone, m 3 ·s -1 ; t is the high tide time; A is the area of ​​the intertidal zone, m 2 ;

[0040] In model (1-13), the pollutant concentration factor uses the average value within the tidal cycle rather than a certain instantaneous value. In a tidal cycle, the average value of flow velocity and substance concentration is as follows:

[0041]

[0042]

[0043] Where τ is the tidal period; μ is the flow velocity (m·s -1 ); C is the pollutant concentration in water (mg·L -1 ).

[0044] As another application of the above-mentioned intertidal zone purification model for pollutants in seawater, the present invention also provides a method for constructing an intertidal zone purification model for phosphorus and nitrogen in seawater for nutrients in seawater, and calculates the intertidal zone purification flux for phosphorus and nitrogen in seawater. Specifically:

[0045] A method for constructing a model for the purification of inorganic phosphorus in seawater by the intertidal zone is as follows: according to the migration and transformation process of inorganic phosphorus in seawater in the intertidal zone, the corresponding terms are selected from the above migration equation (1-12) to obtain

[0046]

[0047] Combined with the value of inorganic phosphorus concentration at the initial moment as C0, the purification model of inorganic phosphorus in seawater in the intertidal zone is obtained as follows:

[0048]

[0049] The calculation method of the intertidal zone's purification flux of inorganic phosphorus in seawater is:

[0050] According to the derivation process of formula (1-13), the solution of the intertidal zone purification model (1-20) for inorganic phosphorus in seawater is:

[0051]

[0052] Based on the amount of inorganic phosphorus purification in seawater by the intertidal zone obtained from formula (1-21), formula (1-16) is used to further calculate the purification flux of inorganic phosphorus in seawater by the intertidal zone.

[0053] A method for constructing a model for purifying nitrogen in seawater in an intertidal zone comprises the following steps:

[0054] A1. The nitrogen includes ammonia nitrogen N1, nitrite nitrogen N2, and nitrate nitrogen N3. The concentrations of ammonia nitrogen, nitrite nitrogen, and nitrate nitrogen are respectively recorded as The unit is mg·L -1 , the change rate of nitrification process is expressed by the following formula:

[0055]

[0056] In the formula is the rate constant for the oxidation of ammonia nitrogen to nitrite nitrogen, It represents the rate constant of oxidation of nitrite nitrogen to nitrate nitrogen;

[0057] when (Unit is d -1 ) is a constant, the above formula (1-22) is a first-order ordinary differential equation system with constant coefficients, and its analytical solution is:

[0058]

[0059] It is related to water temperature, and the relationship can be expressed as follows:

[0060]

[0061]

[0062] Respectively indicate when the water temperature is 20℃ and The value of

[0063] A2. Based on the formula in step A1, according to the migration equation (1-12), and combined with the migration and transformation process of various forms of nitrogen in seawater in the intertidal zone, a purification model of ammonia nitrogen, nitrite nitrogen and nitrate nitrogen in seawater in the intertidal zone is constructed; the initial concentrations of ammonia nitrogen, nitrite nitrogen and nitrate nitrogen are recorded as

[0064] A2-1. When When the intertidal zone is Nitrite Nitrate The purification model is as follows:

[0065]

[0066] A2-2. When At this time, the purification model of ammonia nitrogen, nitrite nitrogen and nitrate nitrogen in seawater in the intertidal zone is as follows:

[0067]

[0068] A method for calculating the nitrogen purification flux of the intertidal zone to seawater is:

[0069] (1) When According to the derivation process of formula (1-13), the intertidal zone can be obtained to be ammonia nitrogen in seawater Nitrite Nitrate The solutions of the purification model (1-24) are:

[0070]

[0071]

[0072]

[0073]

[0074] Based on the purification amount of different forms of nitrogen in seawater by the intertidal zone obtained from formulas (1-26), (1-27) and (1-28), the purification flux of different forms of nitrogen in seawater by the intertidal zone is further calculated using formula (1-16).

[0075] (2) When According to the derivation process of formula (1-13), the intertidal zone can be obtained to be ammonia nitrogen in seawater The solution of the purification model is the same as (1-26), the intertidal zone is responsible for the nitrate nitrogen in seawater The solution of the purification model is the same as equation (1-28), the intertidal zone is responsible for the nitrite nitrogen in seawater The solution of the purification model is:

[0076]

[0077] Based on the purification amount of different forms of nitrogen in seawater by the intertidal zone obtained from formulas (1-26), (1-29), and (1-28), the purification flux of different forms of nitrogen in seawater by the intertidal zone is further calculated using formula (1-16).

[0078] Compared with the prior art, the present invention has the following beneficial effects:

[0079] (1) When constructing the intertidal zone total purification model for pollutants in seawater provided by the present invention, various factors of pollutant migration and transformation in the intertidal zone are considered, an ecological sub-circulation system of pollutants in the intertidal zone is established, and the response relationship process of each subsystem to pollutants in the water is analyzed, thereby determining the variables that cause pollutant changes in the intertidal zone, and then combining the change amount of pollutants caused by each variable to obtain a migration equation, and finally forming a purification model. The present invention combines the characteristics of the intertidal zone and the biogeochemical cycle of pollutants in the intertidal zone to establish a highly matched and comprehensive total purification model for the intertidal zone, which can be used to more comprehensively and deeply study the purification of pollutants in the intertidal zone wetlands that enter the seawater (from sea to land).

[0080] (2) The total purification model of pollutants in seawater by the intertidal zone constructed by the present invention takes into account the migration and transformation processes that may be involved in inorganic or organic pollutants in the intertidal zone water body. The sub-models included in the purification model are relatively complete. Based on this model, according to the characteristics of the migration and transformation of each pollutant, or retaining or deleting the items corresponding to a certain ecological sub-model, the purification model of any pollutant can be obtained. For example, nitrogen and phosphorus do not have volatilization and photolysis processes, so these two items are deleted in the purification model; there is nitrification in the nitrogen cycle, so when constructing purification models of different forms of nitrogen, this process needs to be specially considered. The present invention can facilitate the establishment of a purification model of a pollutant in seawater by the intertidal zone, and then facilitate the study of the purification of a pollutant in seawater by the intertidal zone.

[0081] (3) The total purification model of pollutants in seawater by the intertidal zone constructed by the present invention subtracts the term of pollutants input from the term of pollutant purification. The positive and negative values ​​of the result can indicate the purification effect of the pollutants in the seawater by the intertidal zone. When the result is a negative value, it means that the intertidal zone does not purify the pollutants in the seawater; when the result is a positive value, it means that the intertidal zone purifies the pollutants in the seawater. In addition, according to the established purification model, the purification amount and purification flux of pollutants in the seawater by the intertidal zone can also be calculated, so as to facilitate further research on the degree of purification of pollutants in the seawater by the intertidal zone.

[0082] The present invention will be explained in detail below with reference to the accompanying drawings and specific embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0083] Figure 1 It is a flowchart of the steps of the method for constructing a total purification model of pollutants in seawater in the intertidal zone of the present invention;

[0084] Figure 2 The biogeochemical cycle diagram of the pollutants in the intertidal water in Example 1;

[0085] Figure 3 is a biogeochemical cycle diagram of nutrients in the intertidal zone water body in Example 2;

[0086] Figure 4 Schematic diagram of nitrogen cycle involving microorganisms in Example 2; DETAILED DESCRIPTION

[0087] To facilitate understanding of the present invention, the present invention will be described more comprehensively below with reference to the relevant drawings. Several embodiments of the present invention are given in the drawings, but the present invention can be implemented in different forms and is not limited to the embodiments described in the text. On the contrary, these embodiments are provided to make the content disclosed in the present invention more thorough and comprehensive.

[0088] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly connected by technicians in the technical field to which the present invention belongs. The terminology used in the specification of the present invention is for the purpose of describing specific embodiments and is not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0089] Example 1

[0090] Combined with Figure 1 A method for constructing a total purification model of pollutants in seawater in an intertidal zone comprises the following steps:

[0091] 1.1 Establish an ecological sub-circulation system of pollutants in the intertidal zone:

[0092] When seawater enters the intertidal zone, pollutants in the seawater will undergo a series of physical processes and chemical and biological reactions. The reaction mechanisms and reaction kinetics are very complex. For example, the physical processes include diffusion, convection, suspension, and sedimentation; the chemical processes include oxidation, reduction, adsorption, desorption, complexation, and flocculation; and the biological processes include bioaccumulation, biological uptake, and microbial transformation. Therefore, the migration and transformation process of a pollutant in seawater in the intertidal zone is the result of the combined effects of multiple processes and reactions. Considering the various factors of the migration and transformation of pollutants in the intertidal zone, they are scientifically quantified. The ecological model of pollutants in the intertidal zone includes seven ecological sub-cycles: light, atmospheric deposition, volatilization, aquatic organisms (plants, animals), sediments, suspended particles, and microorganisms.

[0093] In the model ecological cycle, plants and other organisms absorb nitrogen, phosphorus and other substances through photosynthesis under the influence of external environmental factors such as light intensity and water temperature to grow, and consume dissolved oxygen to decompose into inorganic matter and debris. This is a reversible process. Zooplankton ingests pollutants from the water body by feeding, and dead zooplankton can also be decomposed into inorganic matter and debris. The debris will decompose into organic matter while settling, and organic matter can be degraded into inorganic matter. Sediments will release pollutants or debris into the water body. Under the condition of hydrodynamic disturbance, suspended particles will settle or resuspend. Microorganisms can absorb or utilize pollutants in the water body. In addition, organic matter can be converted into inorganic matter through the biochemical action of microorganisms.

[0094] 1.2 Determine the variables causing pollutant changes in the intertidal zone:

[0095] The 11 variables considered in the model are: atmospheric deposition, photolysis process, volatilization process, plant absorption or degradation, animal absorption or release, sedimentation process, resuspension process, sediment adsorption, suspended matter adsorption, sediment desorption or release, and microbial action. Figure 2 This is the response relationship process of each subsystem in the intertidal zone seawater purification model to pollutants in the water. The entire process jointly promotes the progress of intertidal zone seawater purification. These reaction relationships are reflected in the biochemical reaction terms of the model control equation.

[0096] 1.3 Use formula to express the influence of each variable on pollutants:

[0097] (1) Atmospheric deposition

[0098] Atmospheric dry and wet deposition is one of the important ways of material transport in terrestrial and marine ecosystems. Atmospheric deposition flux can be expressed as:

[0099]

[0100] Where r is the sedimentation amount; C is the pollutant mass concentration of the sedimentation sample.

[0101] (2) Photolysis process

[0102] Many chemicals undergo photolysis in water at a wavelength of about 290 nm. The process can be described as:

[0103]

[0104] In the formula, K L is the photolysis rate coefficient; C is the pollutant concentration.

[0105] (3) Volatilization process

[0106] Many organic substances, like organic solvents, have high vapor pressures and evaporate rapidly through the liquid film. This process can be described by the following equation:

[0107]

[0108] In the formula, K V is the volatility coefficient.

[0109] (4) Plant absorption or degradation

[0110] Submerged plants, emergent plants, etc. absorb various substances from the soil (or sediment) mainly through their roots, while phytoplankton absorbs various substances directly from the water. Phytoplankton in water bodies undergo a process of growth, death, and sedimentation, and are affected by predation by zooplankton. The growth rate of phytoplankton is affected by many factors such as water temperature, light intensity, and nutrient concentration. These factors affect the absorption or degradation and release of pollutants in the water by phytoplankton, which can be expressed as follows:

[0111]

[0112] In the formula, A PP is the coefficient of a pollutant in plants; G P , D P are plant growth rate and mortality rate respectively; P is the concentration of phytoplankton.

[0113] (5) Animal absorption or release

[0114] Zooplankton is a natural fish food and plays an important role in the aquatic food chain, especially the changes in its population and quantity. The absorption or release of pollutants in water by zooplankton can be expressed as:

[0115]

[0116] In the formula, C Z , R Z are animal predation rate and mortality rate respectively; Z is the concentration of animals in the water; A Z The coefficient of a certain pollutant contained in an animal.

[0117] (6) Sedimentation process

[0118] Dynamic processes such as sedimentation and accumulation are of great significance for the study of the exchange of chemical elements and the migration of pollutants in the marine environment. This process can be described by the following formula:

[0119]

[0120] In the formula, K s is the sedimentation velocity; C1 is the concentration of particulate pollutants in water.

[0121] (7) Resuspension process

[0122] In the study of sedimentation dynamics in the Yellow River Delta, waves are considered to be the main driving force for erosion and resuspension of seafloor sediments. The change in pollutant concentration in water caused by resuspension can be expressed as:

[0123]

[0124] In the formula, K r is the resuspension coefficient; C2 is the concentration of a pollutant in the sediment.

[0125] (8) Sediment adsorption

[0126] Adsorption of sediment plays an important role in the transport of pollutants, and the process can be described by the following equation:

[0127]

[0128] Where K0 is the adsorption coefficient between sediment and water.

[0129] (9) Suspended matter adsorption

[0130] Suspended particles often interact with pollutants and become their carriers, which largely determines the migration, transformation and circulation fate of pollutants in the environment. This process can be expressed as:

[0131]

[0132] Where K1 is the adsorption coefficient between suspended matter and water.

[0133] (10) Sediment desorption or release

[0134] Wetland sediments can remove pollutants from water bodies through adsorption, but when environmental conditions change, pollutants can be released into the overlying water body through various complex migration and transformation processes. This process can be described by the following formula:

[0135]

[0136] In the formula, K d is the desorption coefficient of the sediment.

[0137] (11) Microbial effects

[0138] Microbial communities are an important component of maintaining wetland ecosystems and achieving ecological purification functions and their material and energy conversion. They are widely used in the removal of nutrients and organic matter in wetland sewage. The impact of microorganisms on pollutants is expressed as:

[0139]

[0140] 1.4 Determine the change in pollutants caused by each variable during the dt period:

[0141] Suppose the concentration of a pollutant in water is C, mg·L -1 In the intertidal zone water area Ω, the purification amount of a pollutant in the time period (t, t+dt) is analyzed. The purification amount of a pollutant in the water body in the time period dt is composed of 11 parts:

[0142] ①The change in pollutants caused by atmospheric deposition is D| t dt;

[0143] ②The change in pollutants caused by photolysis is K L ·C| t dt;

[0144] ③The change in pollutants caused by volatilization is K V ·C| t dt;

[0145] ④The change in pollutants caused by plants is (G P -D P )·P·A PP | t dt;

[0146] ⑤The change in pollutants caused by animals is (C Z -R Z )·Z·A Z | t dt;

[0147] ⑥The change caused by sedimentation is K s ·C1| t dt;

[0148] ⑦The change caused by resuspension is K r ·C2| t dt;

[0149] ⑧The change caused by sediment adsorption is K0·(C2-C)| t dt;

[0150] ⑨The change caused by the adsorption of suspended matter is K1·(C1-C)| t dt;

[0151] ⑩The change caused by desorption is K d ·(C2-C)| t dt;

[0152] The change in pollutants caused by microorganisms is I w | t dt.

[0153] 1.5 Obtain the migration equation for the purification of pollutants in seawater by the intertidal zone:

[0154] Among the above components, the items for purifying pollutants from seawater include photolysis, volatilization, absorption by plants and animals, sedimentation, adsorption by sediments and suspended matter, and microbial action, while the items for inputting pollutants into seawater include atmospheric deposition, resuspension, and desorption or release from sediments. If the item for purifying pollutants is subtracted from the item for inputting pollutants, and the resulting value is negative, it means that the intertidal zone does not purify pollutants in seawater. If the value is positive, it means that the intertidal zone does purify pollutants in seawater.

[0155] Therefore, the purification of any pollutant in the seawater by the intertidal zone can be described by the following migration equation:

[0156]

[0157] 1.6 Obtain the total purification model of pollutants in seawater in the intertidal zone:

[0158] Assume that the distribution law of a pollutant concentration at the initial moment is C0, then C| t＝0 =C0.

[0159] In summary, the overall purification model of pollutants in seawater in the intertidal zone can be summarized as follows:

[0160]

[0161] Based on the above-mentioned total purification model of intertidal zone for pollutants in seawater, the purification amount and purification flux of a certain pollutant in seawater by the intertidal zone are calculated.

[0162] Equation (1-12) is a first-order linear non-homogeneous ordinary differential equation. Rewrite equation (1-12) into the following form:

[0163]

[0164] Using the general solution formula of the first-order linear nonhomogeneous ordinary differential equation, the general solution of equation (1-12) is:

[0165]

[0166] Using the initial conditions in equation (1-14), the solution of model (1-13) for purifying a pollutant in seawater in the intertidal zone is:

[0167]

[0168] Based on the purification capacity of pollutants in seawater by the intertidal zone, the purification flux of a certain pollutant in seawater by the intertidal zone is calculated using the following formula:

[0169]

[0170] Where C is the amount of pollutant purification, mg·L -1 ; Q is the purification flux, mg·m -2 ; v is the flow of seawater into the intertidal zone, m 3 ·s -1 ; t is the high tide time; A is the area of ​​the intertidal zone, m 2 .

[0171] In model (1-13), the pollutant concentration factor uses the average value within the tidal cycle rather than a certain instantaneous value. In a tidal cycle, the average value of flow velocity and substance concentration is as follows:

[0172]

[0173]

[0174] Where τ is the tidal period; μ is the flow velocity (m·s -1 ); C is the pollutant concentration in water (mg·L -1 ).

[0175] Example 2

[0176] According to different pollutants and their main forms of existence, some biochemical reaction items in formula (1-12) are considered in detail, and nutrients are used as an example to illustrate.

[0177] 2.1 Analysis of nutrient elements

[0178] Nutrients are biogenic substances in aquatic ecosystems, directly affecting water productivity and biological resources, and have coupling and feedback mechanisms with global climate change. Nitrogen and phosphorus are essential nutrient elements for the normal growth of plankton in water bodies, but different forms of nitrogen and phosphorus in water bodies have different bioavailability and geochemical behaviors.

[0179] Phosphorus in water bodies mainly exists in dissolved and particulate forms. Dissolved phosphorus mainly includes inorganic phosphorus and organic phosphorus. Dissolved inorganic phosphorus mainly exists in water bodies in the form of orthophosphate (PO4-P), and dissolved organic phosphorus is mainly composed of phospholipids, phosphate sugars, phosphate esters, etc.

[0180] Under the influence of biological factors, nitrogen exists in various forms in the earth's environmental system, including nitrogen (N2), ammonia (NH3), ammonia nitrogen (NH4 + -N), amino nitrogen (NH2 - -N), nitrous oxide (N2O), nitric oxide (NO), nitrogen dioxide (NO2), nitrate nitrogen (NO3 - -N), nitrite nitrogen (NO2 - -N) and organic nitrogen. In aquatic ecosystems, the chemical forms of nitrogen are mainly divided into organic nitrogen and inorganic nitrogen. Organic nitrogen is further divided into dissolved and particulate forms. Dissolved organic nitrogen includes proteins, peptides, amino acids, amino sugars, nucleic acids, chlorophyll and other related pigments, humus, etc. Particulate organic nitrogen is mainly biological debris and living organisms. Inorganic nitrogen is usually some ions that are easily soluble in water, and the most common ones are nitrate nitrogen (NO3 - -N), nitrite nitrogen (NO2 - -N), ammonia nitrogen (NH4 + -N).

[0181] Figure 3 It is the energy and material cycle of nutrients between various purification factors and various driving forces. The purification factors in the ecological model mainly include light, atmospheric deposition, sediment, plants, plant residues, animals, animal residues, microorganisms and suspended particles. The changes in nutrient concentration in the ecological model within a certain period of time are considered in different forms of nitrogen and phosphorus. The phosphorus purification model mainly considers soluble active phosphorus, which is mainly composed of inorganic orthophosphate (PO4-P), which in turn contains H2PO4 - 、HPO4 2- PO4 3- Three forms, mainly PO4 3- The nitrogen purification model mainly considers inorganic nitrogen (NO3 - -N, NO2 - -N、NH4 + -N).

[0182] 2.2 Establishment of a model for the purification of inorganic phosphorus in seawater by the intertidal zone

[0183] The purification process of inorganic phosphorus in seawater entering the intertidal zone includes migration and transformation processes that can reduce or increase inorganic phosphorus. Its reduction is caused by biological absorption and sediment adsorption, while its increase is caused by atmospheric deposition, organic phosphorus degradation, and sediment resuspension. Under anaerobic conditions, sediment release is also a source of inorganic phosphorus in seawater. According to the migration equation (1-12) constructed for pollutants in seawater in the intertidal zone, combined with the migration and transformation process of inorganic phosphorus in seawater in the intertidal zone, we get:

[0184]

[0185] Assuming that the distribution law of inorganic phosphorus concentration at the initial moment is C0, then C| t＝0 =C0.

[0186] In summary, the purification model of inorganic phosphorus in seawater by the intertidal zone can be summarized as follows:

[0187]

[0188] 2.3 Calculation of the purification amount and flux of inorganic phosphorus in seawater by the intertidal zone

[0189] According to the derivation process of formula (1-13), the solution of model (1-20) for purifying inorganic phosphorus in seawater in the intertidal zone is:

[0190]

[0191] Based on the amount of inorganic phosphorus purification in seawater by the intertidal zone obtained from formula (1-21), the purification flux of inorganic phosphorus in seawater by the intertidal zone is further calculated using formula (1-16).

[0192] 2.4 Establishment of a model for the purification of nitrogen in seawater by the intertidal zone

[0193] In the intertidal zone seawater nitrogen purification model, three forms of nitrogen are considered, namely ammonia nitrogen N1, nitrite nitrogen N2, and nitrate nitrogen N3. The decrease of ammonia nitrogen is due to nitrification, biological absorption, and sediment adsorption, while its increase is caused by atmospheric deposition, organic nitrogen degradation, and sediment resuspension; the decrease of nitrite nitrogen is due to its own oxidation to form nitrate nitrogen, and its increase is caused by atmospheric deposition, nitrification of ammonia nitrogen, and sediment resuspension; the decrease of nitrate nitrogen is due to biological absorption and denitrification under anaerobic conditions, and its increase is caused by atmospheric deposition, nitrification, and sediment resuspension. Ammonia nitrogen, nitrite nitrogen, and nitrate nitrogen in the intertidal seawater are mainly nitrified. The nitrification of nitrogen is divided into two processes. First, ammonia is oxidized into nitrite nitrogen by autotrophic bacteria, and then nitrite nitrogen is oxidized into nitrate nitrogen by autotrophic bacteria (such as Figure 4 shown).

[0194] set up Respectively represent the concentrations of ammonia nitrogen, nitrite nitrogen, and nitric nitrogen, in mg·L -1 , the rate of change of nitrification process can be expressed by the following formula:

[0195]

[0196] In the formula is the rate constant for the oxidation of ammonia nitrogen to nitrite nitrogen, represents the rate constant of nitrite nitrogen oxidation to nitrate nitrogen. (Unit is d -1 ) is a constant, the above formula (1-22) is a first-order ordinary differential equation system with constant coefficients, and its analytical solution is:

[0197]

[0198] It is related to water temperature, and the relationship can be expressed as follows:

[0199]

[0200]

[0201] Respectively indicate when the water temperature is 20℃ and The value of .

[0202] In summary, based on the purification model (1-12) that has been constructed for the intertidal zone to pollutants in seawater, and combined with the migration and transformation process of various forms of nitrogen in seawater in the intertidal zone, a purification model for ammonia nitrogen, nitrite nitrogen and nitrate nitrogen in seawater in the intertidal zone was constructed.

[0203] Assume that the initial concentrations of ammonia nitrogen, nitrite nitrogen, and nitrate nitrogen are like The intertidal zone is responsible for ammonia nitrogen in seawater Nitrite Nitrate The purification model is as follows:

[0204]

[0205] like The purification model of ammonia nitrogen, nitrite nitrogen and nitrate nitrogen in seawater by the intertidal zone is as follows:

[0206]

[0207] Under this condition, first calculate the amount of nitrogen purification in seawater by the intertidal zone:

[0208] 2.5 Calculation of the nitrogen purification flux of the intertidal zone in seawater

[0209] (1) In the case of , first calculate the amount of nitrogen purification in the seawater by the intertidal zone:

[0210] According to the derivation process of formula (1-13), the solutions of the purification model (1-24) for purifying ammonia nitrogen, nitrite nitrogen and nitrate nitrogen in seawater in the intertidal zone are:

[0211]

[0212]

[0213]

[0214] Based on the purification amount of different forms of nitrogen in seawater by the intertidal zone obtained from formulas (1-26), (1-27) and (1-28), the purification flux of different forms of nitrogen in seawater by the intertidal zone is further calculated using formula (1-16).

[0215] (2) In the case of , first calculate the amount of nitrogen purification in the seawater by the intertidal zone:

[0216] According to the derivation process of formula (1-13), the solution of the purification model (1-25) of ammonia nitrogen, nitrite nitrogen and nitrate nitrogen in seawater in the intertidal zone can be obtained, among which, the intertidal zone is The solution of the purification model is the same as (1-26), the intertidal zone is responsible for the nitrate nitrogen in seawater The solution of the purification model is the same as equation (1-28), the intertidal zone is responsible for the nitrite nitrogen in seawater The solution of the purification model is:

[0217]

[0218] Based on the purification amount of different forms of nitrogen in seawater by the intertidal zone obtained from formulas (1-26), (1-29), and (1-28), the purification flux of different forms of nitrogen in seawater by the intertidal zone is further calculated using formula (1-16).

[0219] The above is an exemplary description of the present invention in combination with the accompanying drawings. It is obvious that the specific implementation of the present invention is not limited to the above-mentioned method. As long as such non-substantial improvements are made by adopting the method concept and technical solution of the present invention, or the concept and technical solution of the present invention are directly applied to other occasions without improvement, they are all within the protection scope of the present invention.

Claims

1. A method for constructing a total purification model of pollutants in seawater in an intertidal zone, characterized in that: The steps include: S1. Consider various factors affecting the migration and transformation of pollutants in the intertidal zone, quantify them scientifically, and establish an ecological sub-circulation system of pollutants in the intertidal zone; S2. Based on the ecological sub-circulation system of step S1, analyze the response relationship process of each subsystem to pollutants in the water and determine the variables that cause pollutant changes in the intertidal zone; S3, using a formula to express the effect of each variable in step S2 on the pollutant; S4. The concentration of pollutants in water is recorded as C, mg·L -1 , based on the formula in step S3, the amount of pollutant purification is analyzed in the time period (t, t+dt), and the amount of pollutant change caused by each variable in the time period dt is determined; S5. Classify the changes in pollutants caused by each variable into items for pollutant purification and items for pollutant input, and then subtract the items for pollutant input from the items for pollutant purification to obtain the migration equation for pollutant purification in seawater by the intertidal zone; S6. Based on the migration equation in step S5 and the value of pollutant concentration at the initial time, a total purification model of pollutants in seawater in the intertidal zone is obtained.

2. The method for constructing a total purification model of pollutants in seawater in an intertidal zone according to claim 1, characterized in that: In step S2, 11 variables were determined, namely: atmospheric deposition, photolysis process, volatilization process, plant absorption or degradation, animal absorption or release, sedimentation process, resuspension process, sediment adsorption, suspended matter adsorption, sediment desorption or release, and microbial action.

3. The method for constructing a total purification model of pollutants in seawater in an intertidal zone according to claim 2, characterized in that: In step S4, the changes in pollutants caused by various variables during the period dt are: ①The change in pollutants caused by atmospheric deposition is D| t dt; ②The change in pollutants caused by photolysis is K L ·C| t dt;K L is the photolysis rate coefficient; C is the pollutant concentration; ③The change in pollutants caused by volatilization is K V ·C| t dt;K V is the volatility coefficient; ④The change in pollutants caused by plants is (G P -D P )·P·A PP | t dt; A PP G is the coefficient of pollutants in plants; P , D P are plant growth rate and mortality rate, respectively; P is the concentration of phytoplankton; ⑤The change in pollutants caused by animals is (C Z -R Z )·Z·A Z | t dt;C Z , R Z are animal predation rate and mortality rate respectively; Z is the concentration of animals in the water; A Z is the coefficient of animal contaminants; ⑥The change caused by sedimentation is K s ·C1| t dt;K s is the sedimentation velocity; C1 is the concentration of particulate pollutants in water; ⑦The change caused by resuspension is K r ·C2| t dt;K r is the resuspension coefficient; C2 is the pollutant concentration in the sediment; ⑧The change caused by sediment adsorption is K0·(C2-C)| t dt; K0 is the adsorption coefficient between sediment and water; ⑨The change caused by the adsorption of suspended matter is K1·(C1-C)| t dt; K1 is the adsorption coefficient between suspended matter and water; ⑩The change caused by desorption is K d ·(C2-C)| t dt;K d is the desorption coefficient of sediment; The change in pollutants caused by microorganisms is I w | t dt.

4. The method for constructing a total purification model of pollutants in seawater in an intertidal zone according to claim 3, characterized in that: In step S5, the migration equation is:

5. The method for constructing a total purification model of pollutants in seawater in an intertidal zone according to claim 4, characterized in that: In step S6, the pollutant concentration at the initial time is recorded as C0, and the total purification model of pollutants in seawater by the intertidal zone is:

6. An application of an intertidal zone total purification model for pollutants in seawater, characterized in that: Based on the total purification model of pollutants in seawater by the intertidal zone constructed in claim 5, the purification amount and purification flux of pollutants in seawater by the intertidal zone are calculated; specifically: Equation (1-12) is a first-order linear non-homogeneous ordinary differential equation. Equation (1-12) can be rewritten as follows: Using the general solution formula of the first-order linear nonhomogeneous ordinary differential equation, the general solution of equation (1-12) is: Formula (1-14) uses the initial conditions in model (1-13) to obtain the solution of model (1-13): That is, the amount of pollutants in seawater that are purified by the intertidal zone; Based on the purification capacity of pollutants in seawater by the intertidal zone, the purification flux of pollutants in seawater by the intertidal zone is calculated using the following formula: Where C is the amount of pollutant purification, mg·L -1 ; Q is the purification flux, mg·m -2 ; v is the flow of seawater into the intertidal zone, m 3 ·s -1 ; t is the high tide time; A is the area of ​​the intertidal zone, m 2 ; In model (1-13), the pollutant concentration factor uses the average value within the tidal cycle. In a tidal cycle, the average values ​​of flow velocity and substance concentration are as follows: Where τ is the tidal period; μ is the flow velocity (m·s -1 ); C is the pollutant concentration in water (mg·L -1 ).

7. An application of an intertidal zone total purification model for pollutants in seawater, characterized in that: It is applied to establish a model for the purification of inorganic phosphorus in seawater by the intertidal zone. According to the migration and transformation process of inorganic phosphorus in seawater in the intertidal zone, the corresponding items are selected from the migration equation (1-12) described in claim 4 to obtain Combined with the value C0 of inorganic phosphorus concentration at the initial time, the purification model of inorganic phosphorus in seawater in the intertidal zone is obtained as follows:

8. An application of an intertidal zone total purification model for pollutants in seawater, characterized in that: After establishing the intertidal zone purification model for inorganic phosphorus in seawater according to claim 7, the purification amount and purification flux of inorganic phosphorus in seawater by the intertidal zone are calculated, specifically: The solution of the intertidal zone purification model (1-20) for inorganic phosphorus in seawater is: Based on formula (1-21), the amount of inorganic phosphorus purification in seawater by the intertidal zone is obtained using the following formula Where C is the amount of pollutant purification, mg·L -1 ; Q is the purification flux, mg·m -2 ; v is the flow of seawater into the intertidal zone, m 3 ·s -1 ; t is the high tide time; A is the area of ​​the intertidal zone, m 2 ; Then the purification flux of inorganic phosphorus in seawater by the intertidal zone was calculated.

9. An application of an intertidal zone total purification model for pollutants in seawater, characterized in that: It is used to establish a model for the purification of nitrogen in seawater in the intertidal zone, including the following steps: A1. The nitrogen includes ammonia nitrogen N1, nitrite nitrogen N2, and nitrate nitrogen N3. The concentrations of ammonia nitrogen, nitrite nitrogen, and nitrate nitrogen are respectively recorded as The unit is mg·L -1 , the change rate of nitrification process is expressed by the following formula: In the formula is the rate constant for the oxidation of ammonia nitrogen to nitrite nitrogen, It represents the rate constant of oxidation of nitrite nitrogen to nitrate nitrogen; when When is a constant, the above formula (1-22) is a first-order ordinary differential equation system with constant coefficients, and its analytical solution is: It is related to water temperature, and the relationship can be expressed as follows: θ=1.008 θ=1.058 Respectively indicate when the water temperature is 20℃ and The value of A2. Based on the formula of step A1, according to the migration equation (1-12) of claim 4, and in combination with the migration and transformation process of various forms of nitrogen in seawater in the intertidal zone, a purification model of ammonia nitrogen, nitrite nitrogen and nitrate nitrogen in seawater in the intertidal zone is constructed; the initial concentrations of ammonia nitrogen, nitrite nitrogen and nitrate nitrogen are recorded as A2-1. When When the intertidal zone is Nitrite Nitrate The purification model is as follows: A2-2. When At this time, the purification model of ammonia nitrogen, nitrite nitrogen and nitrate nitrogen in seawater in the intertidal zone is as follows:

10. An application of an intertidal zone total purification model for pollutants in seawater, characterized in that: After establishing the intertidal zone purification model for nitrogen in seawater as claimed in claim 9, the purification amount and purification flux of nitrogen in seawater in the intertidal zone are calculated, specifically: (1) When When the intertidal zone is Nitrite Nitrate The solutions of the purification model (1-24) are: Based on the formulas (1-26), (1-27), and (1-28), the purification amount of different forms of nitrogen in seawater in the intertidal zone is obtained, and then the following formula is used Where C is the amount of pollutant purification, mg·L -1 ; Q is the purification flux, mg·m -2 ; v is the flow of seawater into the intertidal zone, m 3 ·s -1 ; t is the high tide time; A is the area of ​​the intertidal zone, m 2 ; Then the purification flux of different forms of nitrogen in seawater in the intertidal zone is calculated; (2) When When the intertidal zone is The solution of the purification model is the same as (1-26), the intertidal zone is responsible for the nitrate nitrogen in seawater The solution of the purification model is the same as equation (1-28), the intertidal zone is responsible for the nitrite nitrogen in seawater The solution of the purification model is: Based on the purification amount of different forms of nitrogen in seawater by the intertidal zone obtained from formulas (1-26), (1-29), and (1-28), the purification flux of different forms of nitrogen in seawater by the intertidal zone is further calculated using formula (1-16).

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