Method for evaluating capability of reducing and degrading organic pollutants by iron in aquifer

Abstract

The invention relates to the technical field of groundwater remediation, in particular to a method for evaluating the capability of reducing and degrading organic pollutants by iron in an aquifer. On the basis of groundwater dynamics and a redox degradation principle between electron acceptor ferric iron and organic pollutants, the invention establishes a method for evaluating the capability of reducing and degrading the organic pollutants by iron by taking solid-phase ferric iron and ferrous iron of an aquifer as indexes. Accurate evaluation of the degradation rate, degradation amount and degradation capability of the organic pollutants is realized, and data guidance is provided for a subsequent site enhanced natural attenuation restoration technology.

Description

Technical Field

[0001] The present invention relates to the technical field of groundwater remediation, and particularly to a method for evaluating the ability of an aquifer to reductively degrade organic pollutants by iron. Background Art

[0002] In recent years, with the rapid development of industrialization and urbanization, the impact of organic pollutants on the groundwater environment has become increasingly serious, even threatening human health and ecological security. An aquifer is the main storage space of groundwater, and it has a certain self-purification ability. Iron reduction degradation in the aquifer is one of the important ways to remove organic pollutants from groundwater. However, due to the complexity and heterogeneity of the aquifer environment, there are still great challenges in accurately evaluating its ability to reductively degrade organic pollutants by iron. Traditional methods for evaluating the ability of an aquifer to reductively degrade organic pollutants mainly involve constructing an artificial aquifer system model to study the activity of iron-reducing bacteria and the degradation efficiency of organic pollutants under specific conditions. However, due to the intricate actual aquifer environment, these methods are difficult to truly reflect the comprehensive influence of various factors in the aquifer environment, and thus cannot achieve accurate evaluation.

[0003] Currently, the evaluation methods for the degradation ability of organic pollutants in an aquifer generally rely on dissolved groundwater chemical components. The most commonly used technical method is the electron acceptor evaluation method, that is, the degradation amount of organic pollutants is calculated by evaluating the consumption of each electron acceptor. Ferric iron (Fe(III)) is an important electron acceptor for the microbial degradation of organic pollutants. However, both Fe(III) and its reduction product ferrous iron Fe(II) are mainly present in the aquifer in the form of solid oxides or hydroxides, and only a very small proportion (usually <2%) exists in the groundwater in the ionic state. This leads to the fact that when using the existing electron acceptor method to evaluate the pollutant degradation ability of an iron-rich aquifer, the contribution of Fe(III) as an electron acceptor to pollutant degradation cannot be objectively and accurately evaluated, resulting in a seriously underestimated evaluation result.

[0004] Therefore, there is an urgent need to develop an evaluation method for the ability of an aquifer to reductively degrade organic pollutants by considering solid-phase Fe (solid compounds containing Fe(III) and Fe(II)) in the aquifer. Summary of the Invention

[0005] In view of this, the present invention provides an evaluation method for the ability of an aquifer to reductively degrade organic pollutants by iron, which can accurately evaluate the degradation ability of reducible organic pollutants in the aquifer.

[0006] To solve the above technical problems, the first aspect of the present invention provides an evaluation method for the ability of an aquifer to reductively degrade organic pollutants by iron, including the following steps:

[0007] According to the results of the site investigation, the pollution source area, the pollution plume, and the unpolluted background area are determined. Multiple sampling points are arranged in the background area, the pollution source area, and the pollution plume respectively. Soil samples are collected at the sampling points, and the distance between the sampling point and the pollution source area is measured and denoted as x.

[0008] The contents of total iron and divalent iron in the soil sample are measured, and the ratio of the content of trivalent iron in each soil sample to the total iron content is calculated. This ratio is denoted as R. Fe(III) Analyze and fit R. Fe(III) The regression equation of the change of R with the distance x is obtained. value;

[0009] Evaluate the degradation rate of organic pollutants according to the model shown in Formula I.

[0010]

[0011] In Formula I, C CH is the content of organic pollutants in the aquifer soil, with the unit of g / kg dry soil;

[0012] is the average value of the total iron content of multiple soil samples, with the unit of g / kg dry soil;

[0013] F is the utilization coefficient of trivalent iron, which is a constant and is calculated according to the chemical reaction equation of organic pollutants and trivalent iron;

[0014] v is the migration velocity of organic pollutants, with the unit of m / d, which is a constant and is obtained according to the hydrogeological parameters of the plot to be evaluated.

[0015] Exemplarily, taking the degradation of benzene in the aquifer as an example, the reaction equation of benzene and trivalent iron is as follows:

[0016] C6H6 + 30Fe(OH)3 + 60H + = 6CO2 + 30Fe 2+ + 78H2O,

[0017] F = the molar ratio of iron atoms to benzene in the reaction formula × the molar mass of iron atoms / the molecular weight of benzene = 30 * 56 / 78 = 21.5 (rounded to 2 decimal places after rounding).

[0018] Combined with the first aspect, the regression equation of the change of R Fe(III) with the distance x is a linear equation of R Fe(III) and x, or a linear equation of lnR Fe(III) and x.

[0019] Combined with the first aspect, the steps of arranging multiple sampling points in the background area, pollution source area, and pollution plume area are specifically as follows: On the center line of the pollution plume and its extension line, multiple sampling points are arranged.

[0020] Combined with the first aspect, in Formula I, the method for obtaining the migration velocity v of organic pollutants according to the hydrogeological parameters of the plot to be evaluated is as follows:

[0021] Obtain the aquifer thickness, permeability coefficient, and hydraulic gradient of the plot to be evaluated by means of unified water level measurement, pumping test, or data collection; calculate the migration velocity v of organic pollutants according to the formula v = permeability coefficient × hydraulic gradient / effective porosity.

[0022] Combined with the first aspect, the above evaluation method further includes the evaluation of the degradation amount of organic pollutants within a time period Δt, and its evaluation model is Formula II or Formula III:

[0023]

[0024] In the formula, k1 is the slope of the regression equation when R Fe(III) is linearly related to x;

[0025] k2 is the slope of the regression equation when lnR Fe(III) is linearly related to x.

[0026] Combined with the first aspect, the above evaluation method further includes the evaluation of the degradation amount of organic pollutants degraded by iron reduction in a certain volume of single-layer aquifer, and its evaluation model is Formula IV:

[0027] M = ΔC CH Vρ, IV

[0028] In the formula, M is the degradation capacity of organic pollutants in the single layer, in g; ρ is the soil bulk density, in kg / m 3 ; V is the volume of the single-layer aquifer in the evaluation area, in m 3 .

[0029] Combined with the first aspect, according to the aquifer conditions or pollution conditions, 1 group or multiple groups of representative aquifer soil samples are collected at each sampling point, and the soil samples are sealed anaerobically, frozen, or refrigerated with a refrigerant.

[0030] Combined with the first aspect, the organic pollutants are reducible organic substances.

[0031] Exemplarily, the reducible organic substances can be petroleum hydrocarbons such as benzene, polycyclic aromatic hydrocarbons such as naphthalene, aldehyde compounds such as formaldehyde, and ketone compounds such as acetone.

[0032] Combined with the first aspect, the trivalent iron content is the difference between the measured total iron content and the divalent iron content.

[0033] Combined with the first aspect, when the dispersion effect is not considered, the migration velocity v of organic pollutants is equal to the actual velocity of groundwater; when making a conservative assessment, the migration velocity v of organic matter is approximately taken as the actual velocity of groundwater.

[0034] Based on the principles of groundwater dynamics and the redox degradation between the electron acceptor ferric iron and organic pollutants, the present invention establishes an evaluation method for the ability of iron reduction to degrade organic pollutants with the solid-phase ferric iron and ferrous iron in the aquifer as indicators, achieving an accurate evaluation of the degradation rate, degradation amount, and degradation ability of organic pollutants, and providing data guidance for subsequent in-situ enhanced natural attenuation remediation technologies. Description of the Drawings

[0035] Figure 1 It is a design diagram of an evaluation conceptual model for the degradation amount of organic matter caused by iron reduction in the aquifer when only considering the migration and transformation of pollutants in one-dimensional direction;

[0036] Figure 2 It is the sampling point and pollution distribution map in the embodiment of the present invention;

[0037] Figure 3 It is the cumulative probability curve of Fe(II) in each monitoring well in the embodiment of the present invention;

[0038] Figure 4 It is the proportion R of Fe(III) in the samples of the pollution source area group and the pollution plume group in the embodiment of the present invention Fe(III) The relationship curve graph with the distance (x) from the sampling point to the edge of the pollution source area. Detailed Embodiments

[0039] In order to make the objectives, technical solutions, and advantages of the present invention clearer, the following further details the present invention in combination with specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0040] Ferric iron Fe(III) is an important electron acceptor for the microbial degradation of organic pollutants. However, Fe(III) and its reduction product ferrous iron Fe(II) generally exist in the aquifer in solid phase form, while the existing evaluation methods for the degradation ability of organic pollutants generally use dissolved-phase electron acceptors in groundwater as indicators, which will seriously underestimate the degradation ability of pollutants caused by Fe(III) reduction metabolism. In view of this, based on the principles of groundwater dynamics and the Fe(III) reduction degradation of organic pollutants, the present invention establishes an evaluation method for the degradation rate, degradation amount, and degradation ability of iron reduction degradation of organic pollutants with solid-phase Fe(III) and Fe(II) in the aquifer as indicators, achieving an accurate evaluation of the degradation ability, degradation rate, and degradation amount of pollutants.

[0041] The technical principle and the derivation of the calculation formula for the method for evaluating the ability of an aquifer to reductively degrade organic pollutants provided by the present invention are as follows:

[0042] Under the action of microorganisms, the ferric iron (hydroxide) in the aquifer can react with petroleum hydrocarbons. While Fe(III) is reduced to Fe(II), the petroleum hydrocarbons also degrade and mineralize. Taking the degradation of the organic pollutant benzene as an example, the degradation equation is as follows, denoted as Equation 1:

[0043] C6H6 + 30Fe(OH)3 + 60H + = 6CO2 + 30Fe 2+ + 78H2O.

[0044] Therefore, in an aquifer contaminated only by petroleum hydrocarbons, the amount of organic matter degradation caused by iron reduction in the aquifer can be estimated based on the disappearance amount of Fe(III) or the generation amount of Fe(II) in the aquifer.

[0045] When only considering the migration and transformation of pollutants in one-dimensional direction, a conceptual model can be generalized as Figure 1 shown. Among them, the x direction is the direction of groundwater flow. The migration distance of pollutants from the pollution source to the evaluation time is l, and the migration speed of pollutants is v. At a position x downstream of the pollution source on the streamline where the pollution source is located, the degradation rate of the pollutant petroleum hydrocarbon (CH) caused by iron reduction, that is, the change of the CH concentration C CH with time

[0046] dC CH

[0047] degree can be expressed by a differential equation as dt. For the convenience of calculation, certain boundary conditions and initial conditions are set.

[0048] Boundary conditions (belonging to assumed conditions):

[0049] (1) On the time scale of observation (since the pollution source leaked), the conversion of Fe(III) to Fe(II) due to natural hydrogeochemical processes can be basically ignored;

[0050] (2) Fe(III) in the aquifer does not migrate (exists in solid form, and the migration amount can be ignored);

[0051] (3) The source strength of pollutants (represented by CH) in the aquifer is a constant source, and the concentration is represented as C 0-CH ;

[0052] (4) The chemical reaction that occurs is an instantaneous reaction, that is, there is sufficient residence reaction time for the pollutants and Fe(III), and the influence of advection-dispersion on the concentrations of the reaction substrates and products can be ignored, and space can replace time;

[0053] Initial conditions: (starting from when the pollution source first enters the aquifer)

[0054] (1) Denote the CH concentration at the pollution source as C 0-CH ;

[0055] (2) Except for the pollution source, the initial CH concentration at other locations in the aquifer is 0;

[0056] (3) The initial Fe(III) concentration in the aquifer is the total iron concentration C Fe ;

[0057] (4) The initial Fe(II) concentration in the aquifer is 0;

[0058] Evaluation model:

[0059] Based on the above conditions, for any point, the relationships between the CH concentration, Fe(III) concentration and time are as follows, denoted as Equation 2:

[0060]

[0061] where C CH is the CH concentration in the aquifer, mg / kg;

[0062] C Fe(III) is the Fe(III) concentration in the aquifer, mg / kg;

[0063] t is the reaction time of CH and Fe(III), d;

[0064] F is the utilization coefficient of Fe(III) calculated according to the above degradation equation. When the organic pollutant is benzene, the corresponding value of F is 21.5.

[0065] Since there is generally no Fe(III) in groundwater, the C Fe(III) in the soil sample collected from the aquifer is the Fe(III) concentration in the aquifer.

[0066] Convert the function of time t on the right side of Equation 2 into a function of the distance x between the sampling point and the organic pollution source, that is:

[0067] At position x, dx = vdt

[0068] Then dt = dx / v. When v is constant, the reaction time of CH and Fe(III) at position x is as follows, denoted as Equation 3:

[0069]

[0070] where l is the migration distance of CH at the evaluation moment, m;

[0071] t is the reaction time of CH at the x position with Fe(III), d;

[0072] v is the migration velocity of the pollutant, m / d.

[0073] Substitute Equation 3 into the right side of Equation 2 to obtain Equation 4:

[0074]

[0075] where, is the change rate of the Fe(III) concentration C Fe(III) with the distance x from the soil sample sampling point to the organic pollution source.

[0076] The C Fe(III) value at the evaluation time can be used for regression analysis with the distance x from the organic pollution source on the center line, and its tangent equation is

[0077] However, in the actual site, due to the difference in the initial Fe(III) concentration, the change of C Fe(III) with the distance x cannot truly reflect the degradation situation of the pollutant. Under this condition, the proportion R Fe(III) of Fe(III) in the total Fe can be used to reflect the pollutant degradation situation, and the total Fe concentration can be represented by the average concentration in the aquifer.

[0078] Therefore, Equation 4 can be corrected to the following Equation 5 (i.e., Equation I):

[0079]

[0081] where, is the average content of the original (before pollution) total Fe in the aquifer, g / kg dry soil.

[0082] When the dispersion effect is not considered (plug flow situation), the migration velocity v of the pollutant is equal to the actual velocity of the groundwater. However, in the actual situation, the migration velocity of the pollutant is greater than the actual velocity of the groundwater. Therefore, for conservative evaluation, v can be approximately taken as the actual velocity of the groundwater.

[0083] (1) When R Fe(III) has a linear relationship with x, the slope k is In this case, Equation 5 can be denoted as Equation 6:

[0084]

[0085] where, k is the slope of the linear regression equation of R Fe(III) with x, mg / kg / m.

[0086] That is, when R Fe(III) varies linearly with the distance x, the degradation rate of CH caused by the reduction of Fe(III) is constant (independent of the change in x). At this time, the degradation of CH follows a zero-order reaction, and the reaction constant is

[0087] Furthermore, the degradation amount of CH during this period can be calculated according to Equation 7 (i.e., Equation II) as follows:

[0088]

[0089] where ΔC CH is the degradation amount of CH at x during a certain period, mg / kg;

[0090] (2) When ln R Fe(III) has a linear relationship with x, its slope k is There is

[0091]

[0092] It can be seen from the above equation that the change in R conforms to the first-order kinetic equation, and its first-order kinetic constant is vk.

[0093] Substitute into the above equation to obtain Equation 8:

[0094]

[0095] That is, the reduction of Fe(III) conforms to the first-order kinetic equation, and its first-order kinetic constant is vk.

[0096] Therefore, when ln R Fe(III) has a linear relationship with x, the reduction amount of Fe at x in a future certain period can be calculated and predicted according to Equation 9:

[0097] ΔC Fe(III) = C Fe(III) (1 - e vkΔt );

[0098] where ΔC Fe(III) is the reduction amount of Fe at x in a future certain period, mg / kg;

[0099] Δt is the evaluation period (cycle), d.

[0100] Furthermore, the degradation amount of CH during this period can be calculated according to Equation 10 (i.e., Equation III) as follows:

[0101]

[0102] Furthermore, the degradation capacity M of iron-reducing organic pollutants in a certain volume of the aquifer within this period can be calculated according to the following formula 11 (i.e., Formula IV):

[0103] M = ΔC CH Vρ

[0104] where M is the degradation capacity of pollutants in a single rock layer, g;

[0105] ρ is the soil bulk density, kg / m 3 ;

[0106] V is the volume of the single-layer aquifer in the evaluation area, m 3 .

[0107] In practical applications, the contents of total iron, ferrous iron, and ferric iron are respectively equal to the contents of effective total iron, effective ferrous iron, and effective ferric iron.

[0108] Example

[0109] This example provides a method for evaluating the ability of iron reduction in an aquifer to degrade organic pollutants. The experimental plot is located in a petroleum-polluted aquifer in the red soil area of South China. The evaluation steps for the ability of iron reduction in the aquifer to degrade benzene, an organic pollutant, include:

[0110] S1. Layout of sampling points: A number of sampling points are laid out in the background area, pollution source area, and pollution plume. The specific layout is as Figure 2 shown.

[0111] S2. Sampling: One or more groups of representative aquifer soil samples are collected at each sampling point, and dry ice refrigerant is used to seal, anaerobically, and freeze the collected soil samples for preservation.

[0112] S3. Obtaining hydrogeological parameters: By means of unified water level measurement, pumping test, data collection and collation, etc., hydrogeological parameters such as the thickness, permeability coefficient, and hydraulic gradient of the aquifer are obtained. Specifically: The average thickness of this aquifer is 4 m, the permeability coefficient is 0.5 m / d, the hydraulic gradient is 0.05, the dry soil density is 1.5 g / cm 3 , the effective porosity is 0.3, and the area of the pollution plume is approximately 3000 m 2 .

[0113] S4. Sample testing: According to the relevant testing standards and specifications for groundwater, the concentrations of total iron, ferric iron Fe(III), and ferrous iron Fe(II) in the collected soil samples are respectively tested. The test results are shown in Table 1 (calculated based on the content of effective iron).

[0114] Table 1 Relevant concentrations of iron in soil samples (unit: mg / L)

[0115] Sample number Total available iron Available Fe(II) Available Fe(III) 2 10.86 0.25 10.61 13 196.43 0.39 196.04 14 93.32 0.42 92.90 3 18.31 0.44 17.87 15 124.30 0.46 123.85 1 25.21 0.54 24.68 12 20.36 1.82 18.55 11 14.85 1.87 12.99 9 84.74 9.85 74.89 10 86.31 11.66 74.64 6 92.15 12.05 80.10 5 115.83 23.81 92.02 4 133.30 26.74 106.56 8 185.36 59.21 126.15 7 181.87 59.71 122.16

[0116] S5. Sample grouping: According to indicators such as the distance of the sampling point from the pollution source, pollutant concentration, and effective Fe(II) content in the aquifer, combined with the groundwater flow, using the cumulative curve method (as Figure 3 shown), the sampling points are divided into background points, plume points, and pollution source area points, and the collected soil samples are correspondingly divided into the background group, plume group, and pollution source area group.

[0117] S6. Calculate the average content of effective total Fe in the aquifer: Using mathematical statistics methods, count the effective total Fe content of all sampling

[0118] —points, and calculate its average content C Fe to be 92.21 mg / kg.

[0119] S7. Obtain the proportion R of the effective Fe(III) content in the corresponding samples of the pollution source area group and the plume group to the total effective Fe Fe(III) (calculated according to the results in Table 1), and measure the distance x between the sampling point corresponding to this sample and the edge of the pollution source area (as shown in Table 2).

[0120] Table 2 Proportion R of the effective Fe(III) content in each sample of the pollution source area group and the plume group Fe(III) and the distance x from the source area

[0121]

[0122]

[0123] S8. Regression analysis of the proportion R of effective Fe(III) Fe(III) changing with the distance x: According to the results in Table 2, perform a regression analysis on the proportion R of effective Fe(III) in the soil samples of the pollution source area group and the plume group Fe(III) and the relationship between the distance (x) of the corresponding sampling point from the edge of the pollution source area (as Figure 4 shown), and solve the value to be 0.0131 / m.

[0124] S9. Calculate the degradation rate: According to the above formula I, calculate the degradation rate to be -0.0047 mg / (kg·d).

[0125] Among them, the migration velocity v of the organic pollutant = permeability coefficient × hydraulic gradient / effective porosity = 0.5 × 0.05 / 0.3 = 0.083 m / d; when the organic pollutant is benzene, the utilization coefficient of Fe(III) is F = 21.5; (rounded to 2 decimal places).

[0126] S10. Calculate the single-point degradation capacity within a certain time period: Using Formula II, the average degradation capacity of the soil with a unit mass within the contaminated plume of the aquifer in one year is -1.70 mg / kg, that is, the soil with a unit mass in the aquifer degrades 1.70 mg / kg on average within one year.

[0127] where k1 = 0.0131, △C CH = -0.083×92.21×0.0131×365 / 21.5 = -1.70 mg / kg (rounded to 2 decimal places).

[0128] S11. Calculate the degradation capacity M of a certain volume of the aquifer in one year: Using Formula IV, the degradation capacity of the aquifer in one year is calculated as: M = △C CH ×V×ρ = -1.70×12000×1500 = -30.6 kg / a, that is, the benzene degradation amount of the aquifer with a volume of 12000 m 3 in one year is 30.6 kg.

[0129] The above is only the preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution of the present invention and its inventive concept, makes equivalent substitutions or changes, and all should be covered within the protection scope of the present invention.

Claims

1. A method for evaluating the ability of an aquifer to reduce and degrade organic pollutants by iron, characterized in that, It includes the following steps: According to the results of the site investigation, determine the pollution source area, the pollution plume, and the unpolluted background area. Arrange multiple sampling points in the background area, the pollution source area, and the pollution plume respectively. Collect soil samples at the sampling points, and measure the distance between the sampling point and the pollution source area, denoted as x; Determine the contents of total iron and divalent iron in the soil sample, calculate the ratio of the content of trivalent iron in each soil sample to the total iron content, and denote this ratio as R Fe(III) , analyze and fit R Fe(III) The regression equation of the change with distance x is obtained value; Evaluate the degradation rate of organic pollutants according to the model shown in Formula I In Formula I, C CH is the content of organic pollutants in the aquifer soil, in g / kg dry soil; is the average total iron content of multiple soil samples, in g / kg dry soil; F is the utilization coefficient of ferric iron, which is a constant and is calculated according to the chemical reaction equation of organic pollutants and ferric iron; v is the migration velocity of organic pollutants, with the unit of m / d, which is a constant and is obtained according to the hydrogeological parameters of the plot to be evaluated.

2. The evaluation method for the ability of an aquifer to reduce and degrade organic pollutants by iron, as described in claim 1, is characterized in that The said R Fe(III) The regression equation varying with the distance x is R Fe(III) A linear equation with x, or lnR Fe(III) A linear equation with x.

3. The method for evaluating the ability of an aquifer to reduce and degrade organic pollutants by iron as described in claim 1, characterized in that The step of arranging multiple sampling points in the background area, the pollution source area, and the pollution plume area specifically is: arrange multiple sampling points on the center line of the pollution plume and its extension line.

4. The method for evaluating the ability of an aquifer to reduce and degrade organic pollutants by iron, as described in claim 1, is characterized in that In Equation I, the method for obtaining the migration velocity v of organic pollutants according to the hydrogeological parameters of the plot to be evaluated is: Obtain the thickness of the aquifer, the permeability coefficient, and the hydraulic gradient of the plot to be evaluated by means of unified water level measurement, pumping test, or data collection; Calculate the migration velocity v of organic pollutants according to the formula v = permeability coefficient × hydraulic gradient / effective porosity.

5. The method for evaluating the ability of an aquifer to reduce and degrade organic pollutants by iron as described in claim 1, characterized in that, It also includes the evaluation of the degradation amount of organic pollutants within a time period △t, and its evaluation model is Equation II or Equation III: where k1 is the slope of the regression equation when R Fe(III) has a linear relationship with x; k2 is lnR Fe(III) The slope of the regression equation when it is linearly related to x.

6. The evaluation method for the ability of an aquifer to reductively degrade organic pollutants as described in claim 1, characterized in that, It also includes the evaluation of the degradation amount of organic pollutants degraded by iron reduction in a single-layer aquifer with a certain volume, and its evaluation model is Equation IV: M = ΔC CH Vρ, Ⅳ Wherein, M is the degradation capacity of organic pollutants in a single rock layer, with the unit of g; ρ is the soil bulk density, with the unit of kg / m 3 ; V is the volume of the single rock layer aquifer in the evaluation area, with the unit of m 3 .

7. The method for evaluating the ability of an aquifer to reductively degrade organic pollutants as described in claim 1, wherein According to the aquifer conditions or pollution conditions, collect 1 set or multiple sets of representative aquifer soil samples at each sampling point, and seal and preserve the soil samples anaerobically, frozen, or refrigerated with a refrigerant.

8. The method for evaluating the ability of an aquifer to reductively degrade organic pollutants as described in claim 1, wherein The organic pollutants are reducible organic substances.

9. The method for evaluating the ability of an aquifer to reductively degrade organic pollutants as described in claim 1, wherein The ferric iron content is the difference between the measured total iron content and the ferrous iron content.

10. The evaluation method for the ability of an aquifer to reduce and degrade organic pollutants by iron, as described in claim 1, is characterized in that When dispersion is not considered, the migration velocity v of organic pollutants is equal to the actual flow velocity of groundwater; when a conservative evaluation is carried out, the migration velocity v of organic substances is approximately taken as the actual flow velocity of groundwater.

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