阅读说明：本技术 动态污染源定位方法 (Dynamic pollution source positioning method ) 是由 李江波 金跃群 于 2020-11-20 设计创作，主要内容包括：本发明公开了一种动态污染源定位方法,属于污染场地修复技术领域。本发明主要通过以污染物作为示踪剂,配合地下水污染物的系统分类、计算机模拟追踪、物探和水文地质技术来精确锁定土壤污染源的位置。本发明在污染修复方案中确定处理重点和优先次序,能够对污染源优先去除,有效遏制污染的扩散,快速使地下水的污染消失,免去区域性的修复工程。(The invention discloses a dynamic pollution source positioning method, and belongs to the technical field of polluted site remediation. The method disclosed by the invention is mainly used for accurately locking the position of the soil pollution source by taking the pollutants as a tracer and matching with the system classification, computer simulation tracking, geophysical prospecting and hydrogeological technologies of underground water pollutants. The invention determines the treatment emphasis and priority in the pollution remediation scheme, can preferentially remove the pollution source, effectively inhibit the pollution diffusion, quickly eliminate the pollution of the underground water and avoid regional remediation engineering.)

1. The dynamic pollution source positioning method is characterized by comprising the following steps:

the method comprises the following steps that firstly, more than one index pollutants are used as tracers, the concentration of the index pollutants is assumed to be a continuous stable field, a pollution source is mainly a point or surface pollution source, the diffusion mode of the pollution source is a radiation mode towards the periphery, the diffusion radius is provided, and the concentration change of the index pollutants is reduced by the same gradient;

sampling underground water at different point positions, measuring the concentration of the index pollutants, drawing a distribution map of the concentration of the index pollutants, and preliminarily judging the number, the range and the type of pollution sources;

setting a plurality of MT observation points in the pollution source range defined in the step two, wherein the MT observation points are positioned on the same straight line in the pollution source range, the apparent resistivity and the phase of each MT observation point are collected in a preset time length, the apparent resistivity curve and the phase curve of each MT observation point are drawn to obtain an MT section of the straight line where the MT observation points are positioned, a nonlinear conjugate gradient method is adopted to carry out two-dimensional inversion on the MT section to obtain a resistivity distribution map on the MT section, if a low-resistance abnormal region is displayed in the resistivity distribution map, the step four is carried out, otherwise, the MT observation points are reset, and the step is repeated until the low-resistance abnormal region is found out;

step four, calling historical land data of the low-resistance abnormal area, obtaining the number and the type of the pollution sources according to the historical land data of the low-resistance abnormal area, comparing the number and the type of the pollution sources preliminarily determined in the step two, and checking whether the missing pollution sources exist or not; if no leakage pollution source exists, the pollution source positioning is finished, otherwise, the fifth step is carried out;

establishing a groundwater fluid model, determining the index pollutants of the omitted pollution source, reversely calculating the possible existence range of the omitted pollution source according to the index pollutant concentration distribution map of the omitted pollution source, and determining the position of the pollution source by performing well drilling observation on the suspected pollution source point and the periphery of the suspected pollution source point in the possible existence range of the omitted pollution source when the possible existence range of the omitted pollution source is smaller than a preset threshold value; and when the possible existence range of the missed pollution source is larger than a preset threshold value, inputting the index pollutant concentration data of the missed pollution source into the underground water fluid model, performing index pollutant migration simulation until the obtained possible existence range of the missed pollution source is smaller than the preset threshold value, and performing well drilling observation on the suspected pollution source point and the periphery of the suspected pollution source point in the possible existence range of the missed pollution source to determine the position of the pollution source.

2. The dynamic pollution source positioning method of claim 1, wherein the concrete method of drilling and observing the suspected pollution source site and the periphery thereof in the fifth step is as follows: and respectively drilling five wells at the suspected pollution source point and the periphery of the suspected pollution source point, analyzing the concentration of the index pollutants of the missed pollution source in the soil and underground water at the well point, selecting one well at the downstream of one well, performing a water pumping test for three to five days, and simultaneously continuously monitoring the water quality.

3. The method according to claim 1, wherein the concentration profile of the indicative pollutants in the second step is implemented by a geographic information system, matlab or surfer software.

4. The method as claimed in claim 1, wherein MT observation points in step three adopt + type distribution table, magnetic north is in x direction, magnetic east is in y direction, measuring electrode distance is 50m, and observation frequency band is 1.0 x 10³Hz～0.5×10²s。

5. The dynamic pollution source positioning method as claimed in claim 1, wherein the method for reversely calculating the possible existing range of the missing pollution source in the step five comprises the following steps: adopting a fuzzy set representation method to obtain the concentration value c of the index pollutants of the missing pollution sources in the underground water with different point positions N_iC (n) is considered as an element of the fuzzy set a of groundwater pollution levels,wherein μ (c)_i) Is c_iThe membership function of the ring type is calculated by the formula

Wherein c is₀The average concentration of the index pollutants of the missing pollution sources, a and b are respectively preset parameters, when mu (c)_i) And when the sampling point is more than or equal to 0.5, the sampling point is in the possible range of the missing pollution source, and the possible range boundary of the missing pollution source can be obtained by connecting the peripheral sampling points.

6. The dynamic pollution source positioning method according to claim 1, wherein the suspected pollution source point in the fifth step is selected by: and in the possible existence range of the missing pollution source, selecting the position close to the possible existence range boundary of the missing pollution source at the upstream of the underground water as the point position of the suspected pollution source according to the underground water fluid model.

Technical Field

The invention relates to the technical field of pollution source positioning. More particularly, the present invention relates to a method for locating a dynamic pollution source.

Background

In contaminated site remediation, the localization of the source of the contamination is a core task. Especially, under the complex environment with multiple pollution types and multiple pollution sources, the positioning of the pollution sources is very difficult. The prior art of the current practical application focuses on delineating the pollution range, carries out classification and investigation on known pollution sources, is similar to the investigation of household mouths, and lacks a recognition and solution method for historical pollution sources and displaced secondary pollution sources. So that a lot of investigation resources are wasted, and the repairing effect is not good for a long time and the reason can not be found. The root cause is because it is not known where the source of the contamination is.

Disclosure of Invention

An object of the present invention is to solve at least the above problems and to provide at least the advantages described later.

The invention also aims to provide a dynamic pollution source positioning method which is suitable for accurate positioning under complex environments with multiple pollution types and multiple pollution sources.

To achieve these objects and other advantages in accordance with the purpose of the invention, there is provided a dynamic pollution source localization method including the steps of:

the method comprises the following steps that firstly, more than one index pollutants are used as tracers, the concentration of the index pollutants is assumed to be a continuous stable field, a pollution source is mainly a point or surface pollution source, the diffusion mode of the pollution source is a radiation mode towards the periphery, the diffusion radius is provided, and the concentration change of the index pollutants is reduced by the same gradient;

sampling underground water at different point positions, measuring the concentration of the index pollutants, drawing a distribution map of the concentration of the index pollutants, and preliminarily judging the number, the range and the type of pollution sources;

setting a plurality of MT observation points in the pollution source range defined in the step two, wherein the MT observation points are positioned on the same straight line in the pollution source range, the apparent resistivity and the phase of each MT observation point are collected in a preset time length, the apparent resistivity curve and the phase curve of each MT observation point are drawn to obtain an MT section of the straight line where the MT observation points are positioned, a nonlinear conjugate gradient method is adopted to carry out two-dimensional inversion on the MT section to obtain a resistivity distribution map on the MT section, if a low-resistance abnormal region is displayed in the resistivity distribution map, the step four is carried out, otherwise, the MT observation points are reset, and the step is repeated until the low-resistance abnormal region is found out;

step four, calling historical land data of the low-resistance abnormal area, obtaining the number and the type of the pollution sources according to the historical land data of the low-resistance abnormal area, comparing the number and the type of the pollution sources preliminarily determined in the step two, and checking whether the missing pollution sources exist or not; if no leakage pollution source exists, the pollution source positioning is finished, otherwise, the fifth step is carried out;

establishing a groundwater fluid model, determining the index pollutants of the omitted pollution source, reversely calculating the possible existence range of the omitted pollution source according to the index pollutant concentration distribution map of the omitted pollution source, and determining the position of the pollution source by performing well drilling observation on the suspected pollution source point and the periphery of the suspected pollution source point in the possible existence range of the omitted pollution source when the possible existence range of the omitted pollution source is smaller than a preset threshold value; and when the possible existence range of the missed pollution source is larger than a preset threshold value, inputting the index pollutant concentration data of the missed pollution source into the underground water fluid model, performing index pollutant migration simulation until the obtained possible existence range of the missed pollution source is smaller than the preset threshold value, and performing well drilling observation on the suspected pollution source point and the periphery of the suspected pollution source point in the possible existence range of the missed pollution source to determine the position of the pollution source.

Preferably, the concrete method for performing well drilling observation on the suspected pollution source site and the periphery thereof in the step five comprises the following steps: and respectively drilling five wells at the suspected pollution source point and the periphery of the suspected pollution source point, analyzing the concentration of the index pollutants of the missed pollution source in the soil and underground water at the well point, selecting one well at the downstream of one well, performing a water pumping test for three to five days, and simultaneously continuously monitoring the water quality.

Preferably, the concentration profile of the indicative pollutants in the second step is implemented by a geographic information system, matlab or surfer software.

Preferably, in the third step, the MT observation point adopts a + type platform, the magnetic north is in the x direction, the magnetic east is in the y direction, the measurement electrode distance is 50m, and the observation frequency band is 1.0 multiplied by 10³Hz～0.5×10²s。

Preferably, the method for reversely calculating the possible existing range of the missing pollution source in the step five comprises the following steps: adopting a fuzzy set representation method to obtain the concentration value c of the index pollutants of the missing pollution sources in the underground water with different point positions N_iC (n) is considered as an element of the fuzzy set a of groundwater pollution levels,wherein μ (c)_i) Is c_iThe membership function of the ring type is calculated by the formula

Wherein c is₀A and b are preset parameters respectively for the average concentration of the index pollutants of the missing pollution source,when mu (c)_i) And when the sampling point is more than or equal to 0.5, the possible range of the missing pollution source exists in the sampling point, and the possible range boundary of the missing pollution source can be obtained by connecting the peripheral sampling point positions.

Preferably, the method for selecting the suspected pollution source point in the fifth step comprises the following steps: and in the possible existence range of the missing pollution source, selecting the position close to the possible existence range boundary of the missing pollution source at the upstream of the underground water as the point position of the suspected pollution source according to the underground water fluid model.

The invention at least comprises the following beneficial effects: compared with the prior art, the dynamic pollution source positioning method provided by the invention gradually reduces the possible existing range of the pollution source, avoids the waste of a large amount of manpower and material resources due to blind investigation, and can find each pollution source one by one when facing the situations of a historical pollution source and a displaced secondary pollution source, thereby being suitable for accurately positioning the pollution source in a complex environment with multiple pollution types and multiple pollution sources.

Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention.

Drawings

FIG. 1 is a schematic diagram of the application of a conventional pollution source locating method in the prior art;

fig. 2 is a schematic diagram of an application of the dynamic pollution source positioning method of the present invention.

Detailed Description

The present invention is further described in detail below with reference to the attached drawings so that those skilled in the art can implement the invention by referring to the description text.

It is to be noted that the experimental methods described in the following embodiments are all conventional methods unless otherwise specified, and the reagents and materials, if not otherwise specified, are commercially available; in the description of the present invention, the terms "lateral", "longitudinal", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, are only for convenience in describing the present invention and simplifying the description, and do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present invention.

As shown in fig. 1, the present invention provides a method for positioning a dynamic pollution source, comprising the following steps:

the method comprises the following steps that firstly, more than one index pollutants are used as tracers, the concentration of the index pollutants is assumed to be a continuous stable field, a pollution source is mainly a point or surface pollution source, the diffusion mode of the pollution source is a radiation mode towards the periphery, the diffusion radius is provided, and the concentration change of the index pollutants is reduced by the same gradient;

there are many types of sources of contamination that may be present in contaminated land, and each type of contamination has its own unique signature of a contaminant diffusing into the soil or even groundwater, such as: heavy metal pollution is usually generated on the land in industrial fields, so that the content of heavy metal in soil and even underground water exceeds the normal concentration range; agricultural land often causes pesticide and fertilizer pollution to land, so that the contents of nitrogen, phosphorus, potassium and some organic pesticides in soil and even underground water exceed the normal concentration range. By examining the index pollutants of the polluted land, the types of pollution sources of the polluted land can be roughly known, and whether various types of pollution sources exist can be roughly known.

Sampling underground water at different point positions, measuring the concentration of the index pollutants, drawing a distribution map of the concentration of the index pollutants, and preliminarily judging the number, the range and the type of pollution sources;

the distribution of the index pollutants at different positions can be visually seen after the drawing of the index pollutant concentration distribution diagram is completed, due to the uncertainty of the position of the pollution source, the maximum concentration in the index pollutant concentration distribution diagram is not necessarily a pollution source, for example, when a plurality of pollution sources of the same type cover the same area, the index pollutant concentration of the area can reach the maximum concentration, but the area does not have the pollution source, and the index pollutant concentration is higher as the area is closer to the pollution source, so that the number, the range and the type of the pollution sources can only be roughly judged by comparing the index pollutant background value of the soil or underground water environment quality standard with the index pollutant concentration distribution diagram.

Setting a plurality of MT observation points in the pollution source range defined in the step two, wherein the MT observation points are positioned on the same straight line in the pollution source range, the apparent resistivity and the phase of each MT observation point are collected in a preset time length, the apparent resistivity curve and the phase curve of each MT observation point are drawn to obtain an MT section of the straight line where the MT observation points are positioned, a nonlinear conjugate gradient method is adopted to carry out two-dimensional inversion on the MT section to obtain a resistivity distribution map on the MT section, if a low-resistance abnormal region is displayed in the resistivity distribution map, the step four is carried out, otherwise, the MT observation points are reset, and the step is repeated until the low-resistance abnormal region is found out;

since the pollutants have certain chemical activity and are easy to generate oxidation-reduction reaction with the soil eroded by the pollutants, metal ions are extracted from the soil and salts are separated out, so that the electrical property of the underground soil is changed, the electrical conductivity and the electrochemical property of the underground soil are enhanced, and obvious electrical property difference is formed between the pollutants and the soil eroded by uncontaminated substances. The low resistance abnormal region is generally referred to as the lowest resistivity region in the resistivity profile on the MT section.

Step four, calling historical land data of the low-resistance abnormal area, obtaining the number and the type of the pollution sources according to the historical land data of the low-resistance abnormal area, comparing the number and the type of the pollution sources preliminarily determined in the step two, and checking whether the missing pollution sources exist or not; if no leakage pollution source exists, the pollution source positioning is finished, otherwise, the fifth step is carried out;

the number and the type of the pollution sources can be obtained according to historical land information of the low-resistance abnormal area, the index pollutants diffused from the pollution sources can be inferred, and the types of the index pollutants in the step one can be compared to judge whether the missed pollution sources exist.

Establishing a groundwater fluid model, determining the index pollutants of the omitted pollution source, reversely calculating the possible existence range of the omitted pollution source according to the index pollutant concentration distribution map of the omitted pollution source, and determining the position of the pollution source by performing well drilling observation on the suspected pollution source point and the periphery of the suspected pollution source point in the possible existence range of the omitted pollution source when the possible existence range of the omitted pollution source is smaller than a preset threshold value; and when the possible existence range of the missed pollution source is larger than a preset threshold value, inputting the index pollutant concentration data of the missed pollution source into the underground water fluid model, performing index pollutant migration simulation until the obtained possible existence range of the missed pollution source is smaller than the preset threshold value, and performing well drilling observation on the suspected pollution source point and the periphery of the suspected pollution source point in the possible existence range of the missed pollution source to determine the position of the pollution source.

The method for reversely calculating the possible existing range of the missing pollution source can adopt the method described in the following embodiment, and of course, other methods in the prior art can also be adopted.

When the possible existing range of the missing pollution source is larger than a preset threshold value, inputting the index pollutant concentration data of the missing pollution source into the underground water fluid model, wherein the underground water fluid model can adopt the following mathematical model:

wherein D is a seepage area of a research area;

K_xx、K_yy、K_zzthe main permeability coefficients in the x, y and z directions, respectively, are given in LT^-1；

S_sIs the water storage rate;

H₀is the initial groundwater level in L

q is the single wide flow at the flow boundary of the study area in L² T^-1

B₂Is a type II boundary;

B₃is a blending boundary;

omega is the rainfall infiltration amount of the upper boundary, and the unit is LT^-1；

ε is the upper bound source sink term in LT^-1；

And sigma is a resistance coefficient.

And the mathematical expression of the indicative pollutant migration is as follows:

wherein:

a_ijminis the dispersivity of the aquifer;

V_m，V_nvelocity components in the m and n directions, respectively;

| V | is the velocity mode;

c is the concentration of the simulated pollutant;

n_eeffective porosity;

c' is the source-sink concentration of the simulated pollutant;

w is the flux over the area of the source sink unit;

V_iis the seepage velocity;

the method is characterized in that a MODFLOW module of GMS software is adopted to simulate underground water flow, an MT3DMS module is used to simulate underground water solute migration, and the possible existing range and emission concentration of a pollution source are inverted through index pollutant migration simulation. In fact, in GMS software, a groundwater fluid model and an index pollutant migration model are preset, so that only relevant data needs to be input to obtain a result.

The preset threshold value of the possible existing range of the missing pollution source is set according to the area of the polluted land in the actual operation process, and is generally 5-10% of the area of the polluted land.

In the practical operation process, the number, the range and the type of the pollution sources are preliminarily judged by drawing an index pollutant concentration distribution map, then the MT profile resistivity distribution map in the existence range of the pollution sources is mapped, the accurate positions of the pollution sources are further verified, whether the missed pollution sources exist or not is checked, finally, the existence range of the missed pollution sources is narrowed again through a groundwater fluid model, the missed pollution sources are accurately positioned by an invasive well drilling observation method, the possible existence range of the pollution sources is gradually narrowed in the whole process, the waste of a large amount of manpower and material resources by blind investigation is avoided, and when the situations of historical pollution sources and displaced secondary pollution sources are met, each pollution source can be found one by one, so that the method is suitable for accurately positioning the pollution sources in the complex environments with multiple pollution types and multiple pollution sources.

To further illustrate the superiority of the present invention, workers were each tested using a conventional method of delineating the source of pollution and then observing the well within the source of pollution (as shown in FIG. 1) and the method of the above example (as shown in FIG. 2), where the contaminated land was not reproducible and thus the conventional method was performed on the contaminated land prior to the method of the present invention. From fig. 1, it can be seen that the whole white area in the black large circle is a pollution area, the black solid small points represent the points of observation wells arranged during pollution source investigation, at this time, the pollution source cannot be accurately positioned, and a method for recognizing and solving the historical pollution source and the moved secondary pollution source is lacked, so that most investigation resources are wasted, and from fig. 2, it can be seen that after the pollution field is treated by the method of the present invention, one observation well (cross circle point in the figure) is selected, a continuous water pumping test is performed for three to five days, and the observation wells are continuously monitored, so that the specific position of the pollution source can be further determined.

In another embodiment, the concrete method for performing well drilling observation on the suspected pollution source site and the periphery thereof in the step five comprises the following steps: and respectively drilling five wells at the suspected pollution source point and the periphery of the suspected pollution source point, analyzing the concentration of the index pollutants of the missed pollution source in the soil and underground water at the well point, selecting one well at the downstream of one well, performing a water pumping test for three to five days, and simultaneously continuously monitoring the water quality. This process allows clean water that is relatively far from the source of contamination to be cleaned, while well water that is downstream of the source of contamination to be altered to contamination.

In another embodiment, the concentration profile of the indicative pollutants in the second step is implemented by a geographic information system, matlab or surfer software.

In another embodiment, in the third step, the MT observation point adopts a + type platform, the magnetic north is in the x direction, the magnetic east is in the y direction, the measurement electrode distance is 50m, and the observation frequency band is 1.0 × 10³Hz～0.5×10²s。

In another embodiment, the method for reversely calculating the possible existing range of the missing pollution source in the step five comprises the following steps: adopting a fuzzy set representation method to obtain the concentration value c of the index pollutants of the missing pollution sources in the underground water with different point positions N_iC (n) is considered as an element of the fuzzy set a of groundwater pollution levels,wherein μ (c)_i) Is c_iThe membership function of the ring type is calculated by the formula

Wherein c is₀The average concentration of the index pollutants of the missing pollution sources, a and b are respectively preset parameters, when mu (c)_i) And when the sampling point is more than or equal to 0.5, the sampling point is in the possible range of the missing pollution source, and the possible range boundary of the missing pollution source can be obtained by connecting the peripheral sampling points. Since different types of pollution sources are all in the same polluted land, and the underground water fluid models are the same, the concentration distribution rules of the index pollutants of different pollution sources in the underground water are basically the same, so the values of the preset parameters a and b can be calculated according to the detected index pollutant concentration of the pollution source and the existence range of the pollution source.

In the embodiment, because the boundary of the range of the pollution source is not clear, the fuzzy set representation method is adopted, when the concentration value of the index pollutant of the missing pollution source in the underground water of a certain point position is larger than the average concentration of the index pollutant of the missing pollution source, when the concentration value of the index pollutant of the missed pollution source in the groundwater of a certain point position is smaller than the average concentration of the index pollutant of the missed pollution source, whether the point position is in the possible existence range of the pollution source needs to be judged through the membership function value of the concentration value of the index pollutant, because groundwater is upstream of the source of contamination, although the targeted contaminant may also diffuse upstream, it is highly likely that the upstream concentration will be less than the average concentration under the influence of the water flow, and the pollution sources can be completely classified in the possible existence range of the missing pollution sources through the judgment of the membership function.

In another embodiment, the point of the suspected contamination source in the fifth step is selected by: and in the possible existence range of the missing pollution source, selecting the position close to the possible existence range boundary of the missing pollution source at the upstream of the underground water as the point position of the suspected pollution source according to the underground water fluid model.

While embodiments of the invention have been described above, it is not limited to the applications set forth in the description and the embodiments, which are fully applicable in various fields of endeavor to which the invention pertains, and further modifications may readily be made by those skilled in the art, it being understood that the invention is not limited to the details shown and described herein without departing from the general concept defined by the appended claims and their equivalents.