A prediction method for soil organic matter migration and degradation based on time dynamic changes

Abstract

The invention discloses a soil organic matter migration and degradation prediction method based on time dynamic change, comprising: collecting data at different soil depths, calculating the content of organic pollutants in the soil; calculating the distribution coefficient of pollutants in the soil; judging the soil NAPL phase based on the distribution coefficient; calculating the migration diffusion coefficient of organic matter based on the distribution coefficient and the judgment result; calculating the comprehensive degradation rate of organic matter, predicting the migration and degradation of organic matter in the soil ecosystem, and obtaining the prediction result; the invention takes into account the NAPL phase judgment, the retention coefficient of organic pollutants of different soil textures; the comprehensive degradation rate of organic matter in the soil, and establishes a degradation time and pollutant concentration-pollutant flux calculation method; establishes a concentration-flux prediction method for organic matter entering the atmospheric breathing layer with floating dust on the surface; and a calculation method for the mixing height and wind speed of the atmospheric breathing layer based on continuous hourly and sequentially meteorological data screening.

Description

Technical Field

[0001] The invention belongs to the field of soil detection, and in particular relates to a method for predicting soil organic matter migration and degradation based on time dynamic changes. Background Art

[0002] The soil ecosystem is composed of soil moisture, soil gas, soil solid particles, and soil microorganisms. Volatile organic matter in the soil can dissolve in soil water to become water-phase pollutants, volatilize in soil gas to become gaseous pollutants, or be adsorbed on soil solid particles. Organic matter that volatilizes in soil gas diffuses from the soil to the surface and enters the atmospheric breathing layer. Organic matter that dissolves in soil water can leach into the groundwater aquifer (the first layer of groundwater). Organic matter adsorbed on soil solid particles can be degraded by soil microorganisms. At the same time, at the contact interface between the soil and the atmospheric breathing layer, organic matter adsorbed on soil solid particles can enter the atmospheric breathing layer with the surface soil dust and become organic pollutants in the form of floating dust particles.

[0003] The recommended model for pollutant diffusion and migration in Appendix F of the existing technology HJ25.3-2019 "Technical Guidelines for Soil Pollution Risk Assessment of Construction Land" simply considers the diffusion of pollutants in the soil, without considering the soil retention coefficient of organic pollutants; the existing technology HJ25.3 simply considers the three-phase equilibrium of pollutants soil-soil air-soil water, without considering the soil NAPL phase; the existing technology HJ25.3 does not consider the degradation of soil pollutants over time; when soil organic matter volatilizes and enters the atmospheric breathing layer with surface dust, the existing technology HJ25.3 simply sets the content of inhalable particulate matter in the air, atmospheric flow velocity, and mixing height as fixed parameters, which is not entirely reasonable. Summary of the invention

[0004] The purpose of the present invention is to provide a soil organic matter migration and degradation prediction method based on time dynamic changes to solve the problems existing in the above-mentioned prior art.

[0005] The present invention establishes a soil three-phase equilibrium model based on the judgment of NAPL phase, considers the influence of soil retention coefficient on organic matter diffusion, comprehensively considers leaching, volatilization, biological action and other factors on the dynamic degradation of soil organic matter, and predicts the concentration and flux of soil organic matter in environmental media such as atmospheric breathing layer and groundwater groundwater. In the method, when soil organic matter volatilizes and enters the atmospheric breathing layer with surface dust, the meteorological data of the evaluation area are counted and screened, the wind speed of the breathing layer under unfavorable meteorological conditions of the site is calculated, the atmospheric vertical diffusion parameters under different atmospheric stabilities are calculated as the mixing height, and the dust-raising model is used to estimate the content of soil particles entering the atmospheric breathing layer.

[0006] To achieve the above object, the present invention provides a method for predicting soil organic matter migration and degradation based on time dynamic changes, comprising:

[0007] Collect soil data at different depths to generate a soil depth data set;

[0008] Calculating the content of comprehensive organic pollutants in the soil based on the soil depth data set;

[0009] Calculating the distribution coefficient of the pollutant in the soil based on the comprehensive organic pollutant content in the soil;

[0010] Judging the soil NAPL phase based on the distribution coefficient and generating a judgment result;

[0011] Calculate the migration and diffusion coefficient of organic matter in the soil ecosystem based on the distribution coefficient and the judgment result;

[0012] The degradation rate of organic matter in soil is calculated based on the migration expansion coefficient, and the migration and degradation of organic matter in the soil ecosystem is predicted to obtain a prediction result.

[0013] Preferably, the soil data set includes: soil comprehensive porosity ratio, comprehensive pore water-gas ratio, comprehensive soil bulk density, and comprehensive organic matter content;

[0014] The soil comprehensive porosity ratio is calculated based on the pore volume ratio at different soil depths and the thickness of the unsaturated layer;

[0015] The water-gas ratio in the comprehensive pores is calculated based on the pore water-gas volume ratio at different soil depths and the thickness of the unsaturated layer;

[0016] The comprehensive soil bulk density is calculated based on the bulk density at different soil depths and the thickness of the unsaturated layer;

[0017] The comprehensive organic matter content is calculated based on the organic matter content and unsaturated layer thickness at different soil depths;

[0018] The soil comprises a soil surface unsaturated layer, a soil middle unsaturated layer, a soil deep unsaturated layer, and a soil deep capillary layer.

[0019] Preferably, the process of calculating the content of comprehensive organic pollutants in soil includes:

[0020] Obtaining organic pollutant contents at different soil depths based on the soil depth data set;

[0021] The comprehensive organic pollutant content is calculated based on the organic pollutant content at different soil depths and the thickness of the unsaturated layer.

[0022] Preferably, the distribution coefficient of the pollutant in the soil includes:

[0023] Partition coefficient of organic matter in soil air-soil water, partition coefficient of organic matter in soil-soil water, partition coefficient of organic matter in soil-soil air;

[0024] The soil gas-soil water distribution coefficient of the organic matter is calculated by Henry's constant, gas constant and soil temperature;

[0025] The soil-soil water distribution coefficient of the organic matter is calculated by the pore water-gas volume ratio in the soil unsaturated layer, the soil solid particle-soil water pollutant distribution coefficient, the soil unsaturated layer bulk density and the soil gas-soil water distribution coefficient;

[0026] The soil-soil air distribution coefficient of the organic matter is obtained by the ratio of the soil air-soil water distribution coefficient of the organic matter to the soil-soil water distribution coefficient of the organic matter.

[0027] Preferably, the determining of the soil NAPL phase comprises:

[0028] When a single organic substance is present, and the solubility of the single organic substance is lower than the saturation solubility in water at the current ambient temperature, there is no NAPL phase;

[0029] When N organic substances are present, if the concentration of dissolved organic pollutants in water is lower than the effective solubility at ambient temperature, there is no NAPL phase.

[0030] Preferably, the migration diffusion coefficient includes:

[0031] The migration diffusion coefficient of soil organic matter in soil air and the migration diffusion coefficient of soil organic matter in soil water;

[0032] The migration diffusion coefficient of soil organic matter in soil gas is calculated by the ideal diffusion coefficient of soil gaseous pollutants in the soil unsaturated layer and the retention coefficient of soil pollutants in the soil unsaturated layer;

[0033] The migration diffusion coefficient of soil organic matter in soil water is obtained by calculating the effective diffusion coefficient of soil water pollutants in the unsaturated layer of soil and different soil depths;

[0034] The effective diffusion coefficient in the unsaturated layer of soil is calculated by using rainfall rate, irrigation rate, terrain length, height difference and water pollutant retention coefficient of soil pollutants in the unsaturated layer of soil;

[0035] The soil pollutant retention coefficient in the unsaturated layer of soil water pollutants is obtained by calculating the soil bulk density, the soil-soil water pollutant distribution coefficient and the soil comprehensive porosity ratio.

[0036] Preferably, the degradation rate of the organic matter in the soil is calculated by the biodegradation rate in the soil, the leaching rate of soil water pollutants, and the gas volatilization rate;

[0037] The soil water pollutant leaching rate is calculated by the diffusion coefficient of soil organic matter in soil water, the soil particle density and the soil air-soil water partition coefficient;

[0038] The gaseous volatilization rate is calculated by the migration diffusion coefficient and height of the soil organic matter in the soil gas and the soil-soil gas distribution coefficient.

[0039] Preferably, the process of predicting the migration and degradation of organic matter in the soil ecosystem and obtaining the prediction result further comprises:

[0040] Calculate the mass concentration of each soil organic matter in each environmental medium and the mass concentration and flux of soil dust organic matter;

[0041] The mass concentration of soil organic matter in various environmental media includes the mass concentration and flux of soil organic matter volatilizing into the atmosphere, and the mass concentration and flux of soil organic matter leaching into groundwater;

[0042] The mass concentration and flux of organic matter in soil dust include the estimation of dust emission, mass concentration and flux of organic matter in dust.

[0043] Preferably, it also includes:

[0044] The atmospheric breathing layer mixing height and breathing layer wind speed are calculated based on the hourly meteorological data for one year;

[0045] The mixing height of the atmospheric breathing layer is obtained by calculating the atmospheric lead value diffusion parameter;

[0046] The breathing layer wind speed is calculated by the wind speed height index, the 1000cm high wind speed in unfavorable weather conditions, and the atmospheric breathing layer mixing height. The technical effects of the present invention are:

[0047] 1. The present invention considers NAPL phase determination, and secondly, the retention coefficient of organic pollutants by different soil textures;

[0048] 2. The present invention takes into account the volatilization, leaching and biodegradation rate of organic matter in the soil, and establishes a calculation method for degradation time and pollutant concentration-pollutant flux;

[0049] 3. When soil organic matter volatilizes and enters the atmospheric breathing layer with the floating dust, the meteorological data of the evaluation area are collected and screened, the wind speed of the breathing layer under unfavorable meteorological conditions of the site is calculated, the vertical diffusion parameters of the atmosphere under different atmospheric stabilities are calculated as the mixing height, and the dust lift model is used to estimate the content of soil particulate matter entering the atmospheric breathing layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] The drawings constituting a part of the present application are used to provide a further understanding of the present application. The illustrative embodiments and descriptions of the present application are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0051] Figure 1 Schematic diagram of the prediction method in an embodiment of the present invention. DETAILED DESCRIPTION

[0052] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0053] It should be noted that the steps shown in the flowcharts of the accompanying drawings can be executed in a computer system such as a set of computer executable instructions, and that, although a logical order is shown in the flowcharts, in some cases, the steps shown or described can be executed in an order different from that shown here.

[0054] Embodiment 1

[0055] In the soil ecosystem, from the surface (soil surface) downward, according to the depth, it can be divided into four parts: the unsaturated layer surv1 of the soil surface (adjacent to the atmospheric breathing layer), the unsaturated layer surv2 of the soil middle layer within 0-20cm below the surface, the unsaturated layer subv of the soil deep layer within 20-50cm below the surface, the capillary layer of the soil deep layer subcap (connected to the phreatic groundwater) within 50cm below the surface. First, calculate the total porosity ratio, pore water volume, and pore air volume of the soil in the four layers respectively, and then calculate the comprehensive total porosity ratio, pore water volume, and pore air volume of the soil.

[0056] According to the bulk density, particle density, moisture content and organic matter content of the four layers of soil, the soil comprehensive porosity ratio, the comprehensive water-gas ratio in the pores, the comprehensive soil bulk density and the comprehensive organic matter content are calculated. The detection indicators are shown in Table 1. The content of organic pollutants in the soil, the calculation of the soil comprehensive porosity ratio, the water-gas ratio in the pores, the comprehensive soil bulk density and the comprehensive organic matter content are as follows:

[0057]

[0058] θ surv1 : Total pore volume ratio in the unsaturated layer of the soil surface, dimensionless; ρ bsurv1 : Soil bulk density in the unsaturated layer of the soil surface, kg / dm 3 ρ s : Soil particle density, kg / dm 3 ;

[0059]

[0060] θ surv2 : Total pore volume ratio in the unsaturated layer of the soil, dimensionless; ρ bsurv2 : Soil bulk density in the unsaturated layer of the soil, kg / dm 3 ;

[0061]

[0062] θ subv : Total pore volume ratio in the deep unsaturated layer of soil, dimensionless; ρ bsubv : Soil bulk density in the deep unsaturated layer, kg / dm 3 ;

[0063]

[0064] θ subcap : the total pore volume ratio in the capillary layer at the soil-groundwater interface, dimensionless; ρ bsubcap : Soil bulk density in the capillary layer at the soil-groundwater interface, kg / dm 3 ;

[0065]

[0066] θ wsurv1 : pore water volume ratio in the unsaturated layer of the soil surface, dimensionless; P wsurv1 : moisture content of the unsaturated layer of the soil surface, kg water / kg soil; ρ w : Density of water, kg / dm 3 , take 1;

[0067]

[0068] θ wsurv2 : The volume ratio of pore water in the unsaturated layer in the middle layer of soil, dimensionless; P wsurv2 : moisture content of the unsaturated layer in the middle layer of soil, kg water / kg soil;

[0069]

[0070] θ wsubv : pore water volume ratio in the deep unsaturated layer of soil, dimensionless; P wsubv : Water content of deep unsaturated layer of soil, kg water / kg soil;

[0071] θ asurv1 =θ surv1 -θ wsurv1 ;

[0072] θ asurv1: The volume ratio of pore gas in the unsaturated layer of the soil surface, dimensionless;

[0073] θ asurv2 =θ surv2 -θ wsurv2 ;

[0074] θ asurv2 : the volume ratio of pore gas in the unsaturated layer in the middle layer of soil, dimensionless;

[0075] θ asubv =θ subv -θ wsubv ;

[0076] θ asubv : the volume ratio of pore gas in the deep unsaturated layer of soil, dimensionless;

[0077]

[0078] θ v : Total pore volume ratio in the unsaturated layer of soil, dimensionless; h v : thickness of unsaturated soil layer, cm; h surv1 : thickness of unsaturated layer on the soil surface, cm; h surv2 : thickness of unsaturated layer in the middle layer of soil, cm; h subv : thickness of deep unsaturated layer in soil, cm;

[0079]

[0080] θ wv : The volume ratio of pore water in the unsaturated layer of soil, dimensionless;

[0081]

[0082] θ av : The volume ratio of pore air in the unsaturated layer of soil, dimensionless;

[0083]

[0084] ρ b : Soil bulk density, kg / dm 3 ρ bsubcap : Capillary layer bulk density at the soil-groundwater interface, kg / dm 3 ρ bsurv1 : Bulk density of unsaturated layer of soil surface, kg / dm 3 ρ bsurv2 : Bulk density of unsaturated layer in the middle layer of soil, kg / dm 3 ρ bsubv : Bulk density of deep unsaturated soil layer, kg / dm 3 ;h subcap: Thickness of capillary layer at soil-groundwater interface, cm;

[0085]

[0086] f om : soil organic matter content, g / kg; f omsurv1 : Organic matter content of unsaturated layer of soil surface, g / kg; f omsurv2 : Organic matter content in the unsaturated layer of the soil, g / kg; f omsubv : Organic matter content in deep unsaturated layer of soil, g / kg; f omsubcap : Organic matter content in the capillary layer of soil groundwater, g / kg;

[0087]

[0088] C sv : mass concentration of organic pollutants in the unsaturated layer of soil, mg / kg; C subv : Mass concentration of organic pollutants in the deep unsaturated layer of soil, mg / kg; C surv1 : Mass concentration of organic pollutants in the unsaturated layer of the soil surface, mg / kg; C surv2 : Mass concentration of organic pollutants in the middle unsaturated layer of soil, mg / kg.

[0089] The scheme is further optimized to determine whether there is an organic phase of organic matter. When the concentration of organic matter is too high, when the value of organic matter in the soil distributed in soil water is higher than the maximum solubility in water, it will precipitate into an organic phase, called the NAPL phase. If a NAPL phase exists, there is no soil water-soil gas-soil solid three-phase equilibrium.

[0090] When there is a single organic matter, if the solubility of the single organic matter is lower than the saturated solubility in water at that temperature, there is no NAPL phase. The method for determining the NAPL phase of a single organic matter is:

[0091]

[0092] S Tenv =S cf ×CF S ;

[0093]

[0094] Among them, T senv : soil ambient temperature, °C; T cf : Correction temperature, °C, take 25; S Tenv : Solubility of organic matter in water at ambient temperature, mg / L; S cf : Solubility of organic matter in water at 25℃, mg / L; Ksw : Soil-soil water pollutant partition coefficient, L / kg; CF s : Water solubility correction factor, dimensionless; △ s H m : water dissolution enthalpy, J / mol, typical value is 10000; R: gas constant, J / (mol·K), take 8.314;

[0095] At soil temperature, the critical concentration of NAPL phase in soil for a single organic matter is

[0096] When judging whether N organic substances exist in the NAPL phase, if the dissolved concentration of all organic pollutants in the water is lower than the effective solubility of the organic pollutant at the temperature, then there is no NAPL phase. The judgment method is:

[0097]

[0098]

[0099] S E iTsenv : The effective saturated solubility of organic matter i in water at ambient temperature when multiple organic pollutants are present, mg / L; MW: relative molecular mass, g / mol.

[0100] To further optimize the scheme, the three-phase distribution coefficient of volatile pollutants in soil liquid phase-soil gas phase-soil solid phase is calculated. The water solubility, vapor pressure and Henry coefficient are related to the measurement temperature. When they are consistent with the actual ambient temperature, correction is required. The correction formula is:

[0101]

[0102]

[0103] H′ Tenv =H′ cf ×CF H′ ;

[0104] CF VP : Vapor pressure correction factor, dimensionless; △ vap H m : Gas vaporization enthalpy, J / mol, typical value is 50000; H' Tenv : Henry coefficient at soil ambient temperature, dimensionless; H' cf : Henry coefficient at corrected temperature, dimensionless; CF H' : Henry function correction coefficient, dimensionless;

[0105] The distribution of organic matter in soil air and soil water is related to the Henry constant or Henry coefficient. The calculation formula of Henry function is:

[0106] The first K aw Calculation formula:

[0107]

[0108] H cf : Henry constant corrected for temperature, pa.m 3 .mol; VP cf : Vapor pressure at corrected temperature, Pa;

[0109]

[0110] K aw : The soil air-soil water partition coefficient of the pollutant, dimensionless;

[0111] The second K aw Calculation formula:

[0112] K aw =H′ Tenv ;

[0113] K aw : The soil air-soil water partition coefficient of pollutants, dimensionless.

[0114] When the three-phase adsorption is in equilibrium, the ratio of the concentration of organic matter in the soil to the mass concentration of organic matter in soil water. The partition coefficient of organic matter between soil solid and soil water K sdw : When the three-phase adsorption is in equilibrium, the ratio of the concentration of organic matter in soil solid particles to the mass concentration of organic matter in soil water. Partition coefficient of organic matter in soil organic carbon-soil water K oc : When the three-phase adsorption is in equilibrium, the ratio of the concentration of organic matter in soil organic carbon to the mass concentration of organic matter in soil water. K oc Can be obtained by query. om The formula is obtained through field testing:

[0115]

[0116] K sdw =K oc ×f oc ;

[0117]

[0118] f oc : soil organic carbon mass fraction, dimensionless; K sdw : Soil solid particles-soil water pollutant distribution coefficient, L / kg; K oc : Soil organic carbon-soil water partition coefficient, L / kg.

[0119] Partition coefficient of organic matter in soil-soil air K sa When the three-phase adsorption is in equilibrium, the ratio of the mass concentration of organic matter in the soil to the mass concentration of organic matter in the soil gas is:

[0120]

[0121] K sa : Soil-soil air organic matter partition coefficient, dm 3 / kg.

[0122] Further optimization scheme, when organic matter migrates and diffuses in soil air and soil water, in addition to the ideal diffusion coefficient related to the diffusion coefficient of organic matter in the atmosphere and pure water, the soil void water ratio, and the soil void air ratio, it is also related to the soil retention coefficient. Therefore, the actual migration diffusion coefficient should be the ratio of the ideal migration diffusion coefficient to the soil retention coefficient, which is closer.

[0123] The calculation model formula of soil organic matter migration diffusion coefficient in soil gas is:

[0124]

[0125] D a : Diffusion coefficient in atmosphere, cm 2 / s;D w : Diffusion coefficient in pure water, cm 2 / s;D sav : Ideal diffusion coefficient of soil gaseous pollutants in the unsaturated layer of soil, cm 2 / s;

[0126]

[0127] R sav : soil pollutant retention coefficient of gas pollutants in the unsaturated layer of soil, dimensionless;

[0128]

[0129] D eff sav : Effective diffusion coefficient of soil gaseous pollutants in the unsaturated layer of soil, cm 2 / s;

[0130]

[0131] D eff atmsub : Surface atmospheric viscosity, diffusion coefficient of sublayer pollutants, cm 2 / s;

[0132]

[0133] D eff sa : Effective diffusion coefficient of soil gaseous pollutants in soil, cm 2 / s;h atmsub : Viscosity sublayer thickness, cm, the thickness is 1 cm.

[0134] The calculation model of the migration diffusion coefficient of soil organic matter in soil water is:

[0135] L gw =h=h surv1 +h surv2 +h subv +h subcap

[0136] L gw : groundwater depth, cm;

[0137]

[0138] D eff swsurv1 : effective diffusion coefficient of soil water pollutants in the unsaturated layer of the soil surface, cm / s;

[0139] △h: terrain height difference, m; L: terrain length, m; φ: surface runoff coefficient, dimensionless; RAIN rate : rainfall rate, cm / s; IRRI rate : irrigation rate, cm / s;

[0140]

[0141] D eff swsurv2 : effective diffusion coefficient of soil water pollutants in the unsaturated layer of the soil, cm / s;

[0142] k' swsurv2 : Soil water permeability coefficient in the unsaturated layer in the middle layer of soil, cm / s;

[0143]

[0144] D eff swsubv : effective diffusion coefficient of soil water pollutants in the deep unsaturated layer of soil, cm / s;

[0145] k' swsubv : Soil water permeability coefficient in the deep unsaturated layer of soil, cm / s;

[0146]

[0147] D effswsubcap : effective diffusion coefficient of soil water pollutants in the soil capillary layer, cm / s;

[0148] k' swsubcap : Soil water permeability coefficient in the soil groundwater capillary layer, cm / s;

[0149]

[0150]

[0151] R swv : soil pollutant retention coefficient of water pollutants in the unsaturated layer of soil, dimensionless;

[0152] D eff sw : Soil effective diffusion coefficient of soil water pollutants, cm / s.

[0153] Further optimization of the scheme shows that the degradation of volatile organic compounds in soil ecosystems includes three parts: biodegradation of organic matter, gas phase of volatile organic compounds, and leaching of soil organic matter into groundwater. The comprehensive degradation of volatile organic compounds in soil ecosystems follows the pseudo-first-order reaction kinetic equation.

[0154] The calculation method of biological degradation rate in soil is:

[0155]

[0156] k sbio : soil biological degradation rate constant, 1 / d; DT 50 : Biodegradation half-life of soil pollutants, d;

[0157] The soil leaching rate is calculated as:

[0158]

[0159] k sgwsvelu : soil leaching pseudo-first-order volatilization rate constant, 1 / d;

[0160] The calculation method of gas evaporation rate is:

[0161]

[0162]

[0163] kasl soil =0.1k sbio ;

[0164]

[0165] k svolat=MAX{k svolat1 , k svolat2};

[0166] k svolat : pseudo-first-order volatilization rate constant of organic matter in soil, 1 / d; kasl air : gas phase mass transfer coefficient at the atmosphere-soil interface, m / d, typical value 90.5; kasl soil : soil mass transfer coefficient at the atmosphere-soil interface, dimensionless; Corr svolat : Correction coefficient of soil mixing layer depth;

[0167] The total degradation rate is calculated as follows:

[0168] k=k sbio +k svolat +k sgwelu ;

[0169] k: comprehensive pseudo-first-order degradation rate in soil, 1 / d.

[0170] To further optimize the plan, hourly meteorological data on total cloud cover, low cloud cover, wind speed, and stability (no less than 4 times a day: 02:00, 08:00, 14:00, and 20:00) will be collected within the site for one consecutive year. In principle, this should be within the past five years. However, if there are no major changes in the meteorological conditions around the site, the meteorological data time can be extended to within the past eight years.

[0171] The mixing height of the atmospheric breathing layer is taken as the average value of the atmospheric vertical diffusion parameter under the stability of the site A~F or the product of the vertical diffusion parameter and the frequency of occurrence of the stability of A~F within the year as the mixing height of the breathing layer.

[0172] When obtaining meteorological data, if the stability can be obtained directly, the frequency of occurrence of A~F stability within the year can be directly calculated; if not, the total cloud cover, low cloud cover, wind speed and longitude and latitude of the observation point can be collected, and the frequency of occurrence of A~F stability within the year can be calculated using the Pasquill stability classification method. The average value of the atmospheric vertical diffusion parameters under the A~F stability of the site can also be taken as the mixing height of the breathing layer.

[0173]

[0174]

[0175]

[0176]

[0177]

[0178] σ z(A-F): Vertical diffusion parameter of atmosphere under AF stability, dimensionless; γ2, α2: Vertical diffusion coefficient, dimensionless, can be queried;

[0179] f A-F : Annual occurrence frequency of A~F stability, dimensionless;

[0180] h bre : Mixing height of breathing layer, cm; A: Area of ​​evaluation area, cm 2 ;

[0181] P: wind speed height index, dimensionless; U 1000cm : 1000cm high wind speed in unfavorable weather, cm / s; U bre : Breathing mixing layer wind speed, cm / s;

[0182] Further optimizing the scheme, the mass concentration and flux of soil organic matter volatilizing into the atmosphere at time t is:

[0183]

[0184]

[0185] C t sbre : At time t, the mass concentration of soil organic matter entering the atmospheric breathing layer in gaseous form, mg / m 3 ;

[0186] F t svol : At time t, the mass flux of soil organic matter entering the atmospheric breathing layer in gaseous form, mg / s.cm 2 ;

[0187] Further optimizing the scheme, the mass concentration and flux of soil organic matter leaching into groundwater at time t is:

[0188]

[0189]

[0190] C t sgw : The mass concentration of soil organic matter leaching into groundwater at time t, mg / L;

[0191] F t sgwsvelu : At time t, the mass flux of soil organic matter entering the atmospheric breathing layer in gaseous form, mg / s.cm 2 .

[0192] The scheme was further optimized to estimate the mass concentration and flux of soil dust organic matter at time t, where the dust emission was estimated as:

[0193] W si =E si ×A;

[0194] E si =I we ×f×CH×(1-η)×10 -7 ;

[0195]

[0196]

[0197] E si : Dust emission coefficient, mg / cm 2 .s;W si : Estimation of dust emission, mg / s; CH: climate factor, dimensionless; η: dust interception efficiency, %; I we : Soil wind erosion index, t / 10 4 m 2 .a, can be queried; f: ground roughness factor, dimensionless, can be queried; p: average annual precipitation, mm; PE Thornworth precipitation-evaporation index, dimensionless;

[0198] Further optimization of the scheme, the mass concentration and flux of organic matter in the floating dust at time t is:

[0199]

[0200]

[0201] C t spis : mass concentration of soil organic matter in airborne dust at time t, mg / m 3 ; F t spis : Mass concentration of soil organic matter in airborne dust at time t, mg / s.cm 2 ; U: average wind speed of 1000cm over many years, cm / s.

[0202] Embodiment 2

[0203] Divide soil testing units, with a side length of 20 to 50 m, to test the mass concentration of soil organic pollutants. Test indicators: C surv1-BaP =C surv2-BaP =0.55mg / kg, C subv-BaP Not detected, so C sv-BaP =0.55mg / kg; C surv1-CCl4 =C surv2-CCl4 =0.9mg / kg, C subv-CCl4 Not detected, so Csv-CCl4 =0.9mg / kg.

[0204] The soil moisture contents of the test sites are: P wsurv1 = 0.285 kg water / kg soil, P wsurv2 =0.21kg water / kg soil, P wsubv = 0.2 kg water / kg soil, soil particle density ρ s Both: 2.53kg / dm 3 The typical value of soil organic matter content is: omsurv1 =f omsurv2 =f omsubv =f omsubcap =17g / kg. The thickness of each layer of soil at the survey site is: h surv1 =20cm,h surv2 =30cm,h subv =145cm, where the thickness of the deep capillary layer of soil is h subcap =5cm is a typical value; ρ bsurv1 =ρ bsurv2 =ρ bsubv =ρ bsubcap =1.43kg / dm 3 .

[0205] The pore water ratios of each layer of soil are calculated as follows: wsurv1 =0.408,θ wsurv2 =0.300,θ wsubv =0.286; the pore-air ratios of each layer of soil are calculated as follows: θ asurv1 =0.027,θ asurv2 =0.134,θ asubv =0.149; the total void ratio of each layer of soil is calculated as: θ surv1 =θ surv2 =θ subv =0.435.

[0206] Then calculate: f om =17g / kg,ρ b =1.43kg / dm 3 θ wv =0.3,θ av =0.134,θ v =0.435.

[0207] To further optimize the scheme, the method for determining whether volatile pollutants exist in the NAPL phase in the soil is as follows:

[0208] When BaP and CCl4 exist alone, C sv-BaP =0.55mg / kg; C sv-CCl4=0.9mg / kg;

[0209] BaP at 25℃, find data, S BaP =0.00162mg / L, T senv =5℃; calculate K sw-BaP ==3323, Because 0.55mg / kg÷3323L / kg=0.000166<0.0012, BaP does not exist in NAPL. When BaP exists in NAPL, the critical value of soil BaP mass concentration is: C svmax-BaP =3323×0.0012=3.988mg / kg.

[0210] Find the data for CCl4 at 25℃, S CCl4 =793mg / L, T senv =5℃, Calculate K sw-CCl4 =0.27, because 0.9mg / kg÷0.27L / kg=3.33<593, there is no NAPL in CCl4, when there is NAPL in CCl4, the critical value of soil CCl4 mass concentration is: 0.27×593=160.11mg / kg.

[0211] When BaP and CCl4 coexist, C sv-BaP =3mg / kg; C sv-CCl4 =150mg / kg, MW BaP =252.31,MW CCl4 =153.84, 3mg / kg÷3323L / kg=0.0009<0.0012, BaP alone does not contain NAPL. 150mg / kg÷0.27L / kg=555.55<593, CCl4 alone does not contain NAPL. Continue to determine whether there is NAPL when BaP and CCl4 coexist. 555.55<592.999, CCl4 and BaP co-exist, CCl4 does not have NAPL, 0.0009>1.19E-9, CCl4 and BaP co-exist, BaP has NAPL.

[0212] To further optimize the scheme, the calculation method for the distribution of volatile pollutants in the three phases of soil liquid phase-soil gas phase-soil solid phase is:

[0213] CF VP(25-5) =0.234, CF S(25-5) =0.748, CF H′(25-5) =0.335, due to f om =17g / kg, so f oc =0.01.

[0214] Find data K oc-BaP =5.87E5L / kg, H′ cf-BaP =1.87E-5, calculate K sdw-BaP =5870L / kg, K aw-BaP =6.26E-6, K sw-BaP =3323L / kg, K sa-BaP =5.333E8dm 3 / kg.

[0215] Find data K oc-CCl4 =4.39L / kg, H′ cf-CCl4 =1.13, calculate K sdw-CCl4 =0.0439L / kg, K aw-CCl4 =0.379, K sw-CCl4 =0.27L / kg, K sa-CCl4 =0.714dm 3 / kg.

[0216] Further optimizing the scheme, the migration diffusion coefficient of soil organic matter in soil gas is calculated as:

[0217] Find data, D a-BaP =0.0476cm 2 / s;D w-BaP =5.56E-6cm 2 / s; calculate the following:

[0218] D sav-BaP =0.0858cm 2 / s,R sav-BaP =1.75E9,

[0219] Find data D a-CCl4 =0.0571cm 2 / s;D w-CCl4 =9.78E-6cm 2 / s; calculate the following:

[0220] D sav-CCl4 =3.78E-4cm 2 / s,R sav-CCl4 =4.508,

[0221] Further optimization plan, in 2021, the maximum rainfall in the evaluation area is in July, 161.1mm, precipitation days are 15.4d, the maximum monthly rainfall rate RAINrate: 16.11÷15.4÷86400=1.211E-5cm / s, the surface runoff coefficient is 0.2, the terrain length L is 20.3m, the elevation difference △h is 2.9m, the soil water permeability coefficient is 1E-6cm / s; the irrigation rate is 0, among which:

[0222] L gw =200cm, R swv-BaP =10950.055, R swv-CCl4 =1.892.

[0223] To further optimize the scheme, the calculation method of biodegradation rate in soil is:

[0224] Find data, D T50-BaP =2100d,D T50-CCl4 =30d, calculate k sbio-BaP =0.00033, k sbio-CCl4 =0.0231.

[0225] To further optimize the scheme, the calculation method for soil water pollutant leaching rate is:

[0226] k sgwelu-CCl4 =0.00063, k sgwelu-BaP =2.28E-9.

[0227] To further optimize the scheme, the calculation method of gaseous volatilization rate is:

[0228] k svolat-CCl4 =0.023, k svolat-BaP =1.19E-6.

[0229] Further optimizing the scheme, the total degradation rate is calculated as:

[0230] k CCl4 =0.047, k BaP =0.00033.

[0231] To further optimize the scheme, calculate the mass concentration of soil organic matter in each environmental medium at time t, collect hourly meteorological data of total cloud cover, low cloud cover, and wind speed (no less than 4 times a day: 02:00, 08:00, 14:00, and 20:00) for the site for 1 year in 5 consecutive years. In principle, it is within the past 5 years, but if there is no major change in the surrounding area of ​​the site that is sufficient to change the meteorological conditions, the meteorological data time can be relaxed to the past 8 years. As shown in Table 1, this embodiment selects hourly meteorological data of the evaluation area in 2015. After screening the meteorological data, the most unfavorable weather is 5 hours of calm and light wind on February 3, 2015, with a stability of F, and an average wind speed of 12 cm / s during the calm and light wind period. P = 0.25, where:

[0232]

[0233] U bre =7.5cm / s.

[0234] Table 1

[0235] Stability F E D C B A α2 0.7844 0.78837 0.826212 0.917595 0.964435 1.12154 γ2 0.0620765 0.0927529 0.104634 0.106803 0.12719 0.0799904 X 20 20 20 20 20 20 σz(AF) 0.6508 0.9841 1.2434 1.6688 2.2867 2.3025

[0236] Further optimizing the scheme, the mass concentration and flux of soil organic matter volatilizing into the atmosphere at time t is:

[0237]

[0238] Further optimizing the scheme, the mass concentration and flux of soil organic matter leaching into groundwater at time t is:

[0239] u gw =0.1m / d=1.16E-4cm / s;

[0240]

[0241] To further optimize the scheme, it is necessary to calculate the mass concentration and flux of soil dust organic matter at time t, and the dust emission amount is estimated as:

[0242] p=570.3mm,I we =51×10 4 t, f = 0.04, U = 294 cm / s;

[0243] PE=526.95,CH=7.657E-10,E si =1.56E-13,W si =6.25E-7mg / s,

[0244] Further optimization of the scheme, the mass concentration and flux of organic matter in the floating dust at time t is:

[0245]

[0246]

[0247] The above is only a preferred specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A method for predicting soil organic matter migration and degradation based on time dynamic changes, characterized in that: The following steps are involved: Collect soil data at different depths to generate a soil depth data set; Calculating the content of comprehensive organic pollutants in the soil based on the soil depth data set; Calculating the distribution coefficient of the pollutant in the soil based on the comprehensive organic pollutant content in the soil; Judging the soil NAPL phase based on the distribution coefficient and generating a judgment result; Calculate the migration and diffusion coefficient of organic matter in the soil ecosystem based on the distribution coefficient and the judgment result; Calculating the degradation rate of organic matter in soil based on the migration diffusion coefficient, predicting the migration and degradation of organic matter in the soil ecosystem, and obtaining a prediction result; The determination of soil NAPL phase includes: When a single organic substance is present, and the solubility of the single organic substance is lower than the saturation solubility in water at the current ambient temperature, there is no NAPL phase; When N organic substances are present, if the concentration of dissolved organic pollutants in water is lower than the effective solubility at ambient temperature, there is no NAPL phase; The migration diffusion coefficient includes: The migration diffusion coefficient of soil organic matter in soil air and the migration diffusion coefficient of soil organic matter in soil water; The migration diffusion coefficient of soil organic matter in soil gas is calculated by the ideal diffusion coefficient of soil gaseous pollutants in the soil unsaturated layer and the retention coefficient of soil pollutants in the soil unsaturated layer; The migration diffusion coefficient of soil organic matter in soil water is obtained by calculating the effective diffusion coefficient of soil water pollutants in the unsaturated layer of soil and different soil depths; The effective diffusion coefficient in the unsaturated layer of soil is calculated by using rainfall rate, irrigation rate, terrain length, height difference and water pollutant retention coefficient of soil pollutants in the unsaturated layer of soil; The soil pollutant retention coefficient in the unsaturated layer of soil water pollutants is calculated by soil bulk density, soil-soil water pollutant distribution coefficient and soil comprehensive porosity ratio; The degradation rate of the organic matter in the soil is calculated by the biodegradation rate in the soil, the leaching rate of soil water pollutants, and the gas volatilization rate; The soil water pollutant leaching rate is calculated by the migration diffusion coefficient of soil organic matter in soil water, soil particle density and soil air-soil water partition coefficient; The gaseous volatilization rate is calculated by the migration diffusion coefficient and height of the soil organic matter in the soil gas and the soil-soil gas distribution coefficient; The process of predicting the migration and degradation of organic matter in the soil ecosystem and obtaining the prediction result also includes: Calculate the mass concentration of each soil organic matter in each environmental medium and the mass concentration and flux of soil dust organic matter; The mass concentration of soil organic matter in various environmental media includes the mass concentration and flux of soil organic matter volatilizing into the atmosphere, and the mass concentration and flux of soil organic matter leaching into groundwater; The mass concentration and flux of organic matter in soil dust include the estimation of dust emission, mass concentration and flux of organic matter in dust; Also includes: The atmospheric breathing layer mixing height and breathing layer wind speed are calculated based on the hourly meteorological data for one year; The mixing height of the atmospheric breathing layer is obtained by calculating the atmospheric lead value diffusion parameter; The breathing layer wind speed is calculated by using the wind speed height index, the 1000 cm high wind speed during unfavorable weather conditions, and the mixing height of the atmospheric breathing layer.

2. The method for predicting soil organic matter migration and degradation based on time dynamic changes according to claim 1 is characterized in that: The soil depth data set includes: soil comprehensive porosity ratio, comprehensive pore water-gas ratio, comprehensive soil bulk density, and comprehensive organic matter content; The soil comprehensive porosity ratio is calculated based on the pore volume ratio at different soil depths and the thickness of the unsaturated layer; The water-gas ratio in the comprehensive pores is calculated based on the pore water-gas volume ratio at different soil depths and the thickness of the unsaturated layer; The comprehensive soil bulk density is calculated based on the bulk density at different soil depths and the thickness of the unsaturated layer; The comprehensive organic matter content is calculated based on the organic matter content and unsaturated layer thickness at different soil depths; The soil comprises a soil surface unsaturated layer, a soil middle unsaturated layer, a soil deep unsaturated layer, and a soil deep capillary layer.

3. The method for predicting soil organic matter migration and degradation based on time dynamic changes according to claim 1 is characterized in that: The process of calculating the level of integrated organic pollutants in soil involves: Obtaining organic pollutant contents at different soil depths based on the soil depth data set; The comprehensive organic pollutant content is calculated based on the organic pollutant content at different soil depths and the thickness of the unsaturated layer.

4. The method for predicting soil organic matter migration and degradation based on time dynamic changes according to claim 1 is characterized in that: The distribution coefficients of the pollutants in soil include: Partition coefficient of organic matter in soil air-soil water, partition coefficient of organic matter in soil-soil water, partition coefficient of organic matter in soil-soil air; The soil gas-soil water distribution coefficient of the organic matter is calculated by Henry's constant, gas constant and soil temperature; The soil-soil water distribution coefficient of the organic matter is calculated by the pore water-gas volume ratio in the soil unsaturated layer, the soil solid particle-soil water pollutant distribution coefficient, the soil unsaturated layer bulk density and the soil gas-soil water distribution coefficient; The soil-soil air distribution coefficient of the organic matter is obtained by the ratio of the soil air-soil water distribution coefficient of the organic matter to the soil-soil water distribution coefficient of the organic matter.

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