Method suitable for tracing copper and nickel pollution of underground water in village-town-level industrial cluster area

Abstract

The invention provides an underground water copper and nickel pollution traceability method suitable for a village-town-level industrial cluster area, relates to the technical field of underground water pollution traceability, and is sequentially carried out according to source identification, source preliminary judgment and source evidence stages under the condition of meeting traceability starting conditions. According to the method, the pollution area is determined by judging the standard exceeding degree of copper and nickel, the traceability range is delineated in combination with hydrogeological data and the Darcy law, a potential pollution source screening list is established, and source-approach-receptor pollution possibility analysis is carried out; under a multi-source condition, a suspected pollution source is determined by adopting a geophysical method and / or batched well building water quality analysis, and a final traceability conclusion is obtained through evidence of multiple technologies such as hydrochemistry, isotope, numerical simulation and tracer agent tracing when necessary. The method is staged, can jump, is high in technology coupling, and can improve the accuracy and the implementability of underground water pollution traceability in a complex area on the premise of controlling the cost.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of groundwater pollution tracing, in particular to a method for tracing copper and nickel pollution in groundwater in a village-level industrial cluster area. BACKGROUND

[0002] At present, the industry is developing rapidly, and the scale and number of various industrial clusters and industrial parks are increasing. With the continuous advancement of industrialization and urbanization, the copper and nickel pollution problem of groundwater environment in industrial clusters is becoming increasingly prominent, becoming a major environmental hidden danger that restricts the sustainable development of economy and society and threatens public drinking water safety. Village-level industrial clusters, as highly concentrated areas of human production activities, have problems such as mixed layout, disordered development, frequent iteration, and insufficient management. Long-term gathering of various polluting industries such as chemical industry, dyeing, electroplating, pharmaceuticals, and leather making, the copper and nickel heavy metals involved in the production process may enter the groundwater system through leakage, leakage, overflow, and other ways, causing irreversible pollution damage. Compared with traditional surface water pollution, groundwater pollution has the characteristics of strong concealment, wide diffusion range, high treatment cost, and long repair period. Once polluted, it will pose a serious threat to regional water resources safety, ecological system health, and human health, so it is urgent to develop high-precision tracing technology.

[0003] Due to the difficulty of groundwater observation and other practical conditions, the current tracing technology for nickel and copper pollution in groundwater mainly through the construction of monitoring wells and the monitoring of concentration, drawing the spatial distribution map of pollutant concentration, and then superimposing it with the existing enterprise spatial distribution to realize the tracing of the location of pollution leakage source. This method can achieve good results when applied to closed sites or homogeneous strata. The tracing accuracy of the traditional method depends on the spatial density of the built wells and the sample analysis accuracy. If high-precision tracing and exclusion of multiple source interference are required, the tracing cost is high. At the same time, this method has high requirements for the monitoring well construction environment in the tracing area, which should generally be a shutdown area. However, due to the influence of historical development, the industrial layout in the village-level industrial cluster area has the characteristics of spatial compactness, diverse types of enterprises, frequent iteration, staggered production and shutdown, and complex pollution sources. At the same time, affected by the regional hydrogeological conditions, the upstream and downstream relationships of groundwater change frequently and exist repeatedly. The typical production mode makes it difficult to place monitoring wells in the ideal position in actual tracing work.

[0004] Overall, the existing copper and nickel pollution tracing method for groundwater has the problems of high tracing cost, lack of tracing accuracy, and other problems caused by single technical support, no differentiated regional investigation, and in-production and spatial environment restrictions when applied to rapidly iterating village-level industrial clusters. SUMMARY

[0005] In order to overcome the deficiencies of the prior art, the purpose of the present application is to provide a method suitable for village and town level industrial cluster area groundwater copper and nickel pollution tracing, by identifying the actual conditions of the pollution area, systematically organizing the optimal tracing path, and carrying out the tracing work in stages, steps and multi-technology coupling, to overcome the problems of high difficulty, high cost and lack of precision in the village and town level industrial cluster area.

[0006] In order to achieve the above-mentioned purpose, the present application provides the following scheme:

[0007] A method suitable for village and town level industrial cluster area groundwater copper and nickel pollution tracing, under the condition of meeting the groundwater pollution tracing starting condition, in the order of source identification, source preliminary judgment and source evidence stage, comprising:

[0008] Determine the copper and nickel indicators as the tracing indicators and determine the over-standard degree to determine the pollution area;

[0009] Collect hydrogeological data of the pollution area, and determine the preliminary range based on the minimum hydrogeological unit boundary, and calculate the pollution migration distance based on the Darcy law based on the preliminary range to determine the tracing range;

[0010] Collect land use history and potential pollution source data within the tracing range, and establish a preliminary screening list and a key screening list;

[0011] Carrying out "source-path-receptor" pollution possibility analysis on the key screening list, screening the potential pollution sources, and drawing a spatial distribution map, if there is only a single potential pollution source, it is determined as the actual pollution source;

[0012] If there are multiple potential pollution sources, determine and / or build wells in batches and analyze the pollution concentration spatial distribution map through geophysical methods, and determine the suspected pollution source according to the overlay comparison;

[0013] If the actual pollution source still cannot be directly identified, at least two of water chemical analysis, isotope tracing analysis, numerical simulation tracing analysis and tracer tracing analysis are used for evidence, if two or more technologies point to the same tracing conclusion, the process is ended, otherwise, the tracer tracing analysis conclusion is taken as the final tracing conclusion.

[0014] Preferably, the groundwater pollution tracing starting condition includes: through the construction of groundwater environmental monitoring well and water quality analysis, it is found that the water quality appears obvious human factors leading to deterioration; or in the process of extracting groundwater for production activities, the sensory properties of color and odor are obviously changed due to abnormal water quality; or there is an emergency event that may exist potential groundwater pollution and needs further investigation.

[0015] Preferably, the degree of exceeding the standard is determined according to GB / T 14848-2017, and copper exceeding class IV is pollution, and copper exceeding class IV by more than 10 times is serious pollution, and nickel exceeding class IV is pollution, and nickel exceeding class IV by more than 10 times is serious pollution.

[0016] Preferably, when calculating the pollution migration distance L according to Darcy's law, the permeability coefficient K is given based on regional hydrogeological data, the hydraulic gradient J is given based on regional hydrogeological data and is defaulted to 2‰, the migration and diffusion time t is determined according to the regional land use time and is defaulted to 5000 days, and the pollution migration distance L is taken as the farthest pollution upstream investigation distance.

[0017] Preferably, the preliminary screening list at least includes the spatial position of the potential pollution source, the main production process or raw and auxiliary materials, and the production scale; and the key screening list at least includes the potential pollution source code, the potential pollution source name, the potential pollution source spatial position, and the potential pollution source way of causing copper and nickel pollution of groundwater.

[0018] Preferably, the "source-path-receptor" pollution possibility analysis includes: excluding enterprises or artificial activity areas with anti-leakage measures in combination with pollution leakage prevention conditions; excluding enterprises or artificial activity areas downstream of the pollution area when the groundwater flow direction is clear in combination with hydrogeological conditions; for the traceability scenario that the total amount Q of pollutants can be calculated according to the pollution concentration and the pollution area range, determining the proportion of the maximum pollution level to the total amount Q of pollutants, and if the proportion exceeds 10%, it is considered to have pollution potential, and if it is less than 10%, it is considered to have no pollution potential.

[0019] Preferably, the execution condition of the geophysical method determination is that the pollution area belongs to serious pollution and there is no underground pipeline restriction within the traceability range.

[0020] Preferably, the geophysical method determination adopts high-density resistivity method, and is carried out in the direction of the connecting line of the potential pollution source and the pollution area and the vertical direction thereof, and includes project design and field arrangement, data acquisition and preprocessing, inversion modeling, result interpretation and report preparation.

[0021] Preferably, the batch well construction and water quality analysis include first batch well construction, the first batch of traceability wells are arranged around the pollution area, and the traceability well arrangement position is located at the intermediate position of the pollution area and the potential pollution source, the number of traceability well arrangement is not less than the number of potential pollution sources, and the traceability well arrangement depth is in the same underground aquifer as the pollution area; if only one traceability well detects pollution after monitoring, the corresponding potential pollution source is locked as a suspected pollution source and the second batch of well construction is skipped.

[0022] Preferably, the batch well construction and water quality analysis further comprises a second batch well construction, the second batch of trace wells are arranged around the high correlation potential pollution source identified by the first batch of well construction, the number of trace wells meets the control of the main direction of pollution migration and diffusion, and is mainly arranged downstream of the potential pollution source and upstream of the pollution area, and the depth of the trace well is adjusted to the trace pollution layer.

[0023] Preferably, when the spatial distribution of the pollution concentration is dense and cannot be qualitatively judged whether the spatial distribution of the potential pollution source is superimposed, the center position of the spatial distribution of the pollution concentration is determined by using the first moment calculation, and the distance difference between the center position and each potential pollution source is used to judge the strength of the pollution correlation.

[0024] Preferably, after the second batch of well construction is completed, the detection data of the two batches are used to draw a pollution concentration spatial distribution graph and compare it with a potential pollution source spatial distribution graph, if there is only one and independent pollution plume distribution, the potential pollution source overlapping with the pollution plume is converted into an actual pollution source and the process is ended, if there is a continuous pollution plume distribution, all potential pollution sources in the pollution plume distribution range are converted into suspected pollution sources and enter the source evidence stage.

[0025] Preferably, the time and economic cost of the multiple technical means used in the source evidence stage increases in turn, if two or more technical means point to the same trace source conclusion, the process is ended, if two or more technical means do not point to the same trace source conclusion and the result of the foregoing stage is correct, the conclusion obtained by the tracer tracing and trace source analysis is taken as the final trace source conclusion.

[0026] Preferably, the numerical simulation trace source analysis comprises hydrogeological model construction, numerical simulation model construction, pollution migration simulation and prediction, potential pollution source correlation analysis, and simulation based on the constitutive equation to compare the spatial correlation of the simulated pollution plume and the actual pollution plume.

[0027] Preferably, the tracer tracing and trace source analysis comprises tracer selection, migration and diffusion monitoring, and result interpretation, the tracer is a naturally existing tracer or a man-made added tracer, and the tracer is added in the wells around the potential pollution source, sampling and concentration monitoring are carried out in other monitoring wells, and if necessary, new wells are constructed on the migration and diffusion path to depict the tracer migration channel.

[0028] Preferably, after the actual pollution source is obtained, well construction is carried out around the single or multiple actual pollution sources and the pollution range is delimited, the monitoring wells are arranged around the actual pollution source and the pollution area, and the determined pollution boundary is used as the basis for the subsequent treatment process.

[0029] The present application discloses the following technical effects:

[0030] 1) High accuracy: Compared with traditional single technology traceability method, this method can significantly improve the traceability accuracy when applied to the traceability of copper and nickel indicators in the village and town level industrial cluster area;

[0031] 2) Low cost: By means of "time for space", the traceability work is carried out in stages, avoiding indiscriminate "detailed investigation" to delimit the pollution range, saving economic cost;

[0032] 3) Wide applicability: The single technology involved in this method is mature, and after systematic combination, it can be widely applied to the traceability demand in the special environment of village and town level industrial cluster area, providing key support for the identification of pollution responsibility, efficient repair and treatment of pollution source. BRIEF DESCRIPTION OF DRAWINGS

[0033] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed in the embodiments will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0034] Figure 1 The method flowchart provided for the embodiments of the present application;

[0035] Figure 2 The technical route schematic diagram provided for the embodiments of the present application;

[0036] Figure 3 The first batch of traceability well layout schematic diagram provided for the embodiments of the present application;

[0037] Figure 4 The second batch of traceability well layout schematic diagram provided for the embodiments of the present application;

[0038] Figure 5 The third batch of traceability well layout schematic diagram provided for the embodiments of the present application. DETAILED DESCRIPTION

[0039] The technical solutions in the embodiments of the present application will be described clearly and completely with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some embodiments of the present application, not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0040] The application aims to provide a method for tracing the source of groundwater pollution by copper and nickel in a village-level industrial cluster area, which realizes high-precision, verifiable and land-based identification of complex groundwater pollution sources in a village-level industrial cluster area without increasing unnecessary monitoring costs by constructing a groundwater pollution source tracing process in stages and with jumping, and organically coupling hydrogeological analysis, spatial overlay, batch well construction and multi-technology evidence.

[0041] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the present application will be further described in detail below in combination with the drawings and specific embodiments.

[0042] Figure 1 As shown in the method flowchart provided by the embodiments of the present application, Figure 1 the present application provides a method for tracing the source of groundwater pollution by copper and nickel in a village-level industrial cluster area, which is executed in the order of source identification, source preliminary judgment and source evidence collection under the condition of meeting the starting condition of groundwater pollution source tracing, and includes the following steps.

[0043] Step 100: determining the indicators to be traced as copper and nickel indicators and judging the exceeding degree, and determining the pollution area;

[0044] Step 200: collecting hydrogeological data of the pollution area, circumscribing a preliminary range according to the boundary of the minimum hydrogeological unit, and calculating the pollution migration distance based on the preliminary range according to Darcy's law to determine the tracing range;

[0045] Step 300: collecting land use history and potential pollution source data within the tracing range, and establishing a preliminary screening list and a key screening list;

[0046] Step 400: carrying out a pollution possibility analysis of "source-path-receptor" on the key screening list, screening a potential pollution source, and drawing a spatial distribution map, and if there is only a single potential pollution source, it is determined as the actual pollution source;

[0047] Step 500: if there are multiple potential pollution sources, determining and / or constructing a batch well and analyzing the water quality to obtain a pollution concentration spatial distribution map, and determining a suspected pollution source by overlay comparison;

[0048] Step 600: if the actual pollution source cannot be directly identified, at least two of water chemical analysis, isotope tracing analysis, numerical simulation tracing analysis and tracer tracing analysis are used for evidence collection, if the conclusions of two or more technologies point to the same source, the process is ended, otherwise, the conclusion of the tracer tracing analysis is taken as the final tracing conclusion.

[0049] Groundwater refers to the water body existing below the ground surface, and its pollution process often presents the characteristics of unobservability, pollution lag and difficulty in reversing. In order to realize the source control of groundwater pollution and realize the treatment of groundwater pollution at a low cost, it is necessary to carry out the source tracing work of the discovered groundwater pollution. The existing groundwater copper and nickel pollution source tracing work in the village and town level industrial cluster area often presents the characteristics of single technical support, no differentiated regional investigation, production and spatial environment limitation and the like. In the actual application process, the groundwater pollution source tracing work is prone to problems such as high source tracing cost and lack of source tracing accuracy. Based on the actual situation of the groundwater copper and nickel pollution process, the present invention adopts the source tracing idea of stages, steps and multi-technology coupling, and systematically carries out the pollution source tracking work. On the basis of fully integrating the existing data, combined with the specific situation in the source tracing process, the corresponding time and human resources are gradually invested to significantly improve the source tracing accuracy under the premise of controlling the cost.

[0050] 1. Groundwater pollution source tracing starting condition

[0051] The groundwater pollution source tracing starting condition of the present method is that when the water quality appears obvious human factor leading to deterioration through groundwater environmental monitoring well construction and water quality analysis process, or when the color, odor and other sensory properties are obviously changed due to abnormal water quality in the process of extracting groundwater for production activities, or when there is an emergency event, which may cause potential groundwater pollution and needs further investigation.

[0052] Under the condition of meeting the groundwater pollution source tracing starting condition, the source tracing work is carried out according to the following groundwater pollution source tracing work steps.

[0053] 2. Groundwater pollution source tracing work steps

[0054] The groundwater copper and nickel pollution source tracing method of the present invention mainly includes three stages of potential pollution source identification, suspected pollution source determination and actual pollution source evidence (hereinafter referred to as source identification, source preliminary determination and source evidence), and the overall source tracing stage is executed in order. Among them, the source identification stage is a necessary source tracing stage, the source tracing result of the previous stage can be used as the basis for whether to carry out the source tracing of the next stage, and the source tracing of the subsequent stage can be skipped when the certain stage source tracing condition is met.

[0055] In the present embodiment, in order to ensure that the groundwater copper and nickel pollution tracing method is executable and decision consistent under the complex conditions of village and town level industrial clusters, the entry conditions, exit conditions and stage jump rules of the source identification stage, the source preliminary judgment stage and the source corroboration stage are uniformly set. The "stage jump" refers to directly terminating the groundwater pollution tracing process or skipping the subsequent stage when the preset tracing judgment condition is met, which is used to avoid indiscriminate high-cost investigation, so as to achieve a reasonable balance between tracing accuracy and engineering cost. In the present embodiment, the judgment results of each stage are used as the only basis for whether to start the next stage, ensuring that the tracing process has clear decision logic and result traceability.

[0056] In the present embodiment, the source identification stage is a necessary stage for groundwater copper and nickel pollution tracing, and is automatically executed after the groundwater pollution tracing start condition is met. The core output of this stage is "potential pollution source", which refers to an enterprise or human activity area within the tracing range that has the possibility of causing groundwater copper and nickel pollution after screening by land use history, industry type and pollution mode. Its function is to narrow the scope of investigation objects in the subsequent tracing. If only one potential pollution source is identified after the "source-path-receptor" pollution possibility analysis, for example, there is only one enterprise involving electroplating process and having leakage risk within the tracing range, the present embodiment directly determines the potential pollution source as the actual pollution source and terminates the groundwater pollution tracing process. If two or more potential pollution sources are identified, the source preliminary judgment stage is automatically entered for further execution.

[0057] In the present embodiment, the entry condition of the source preliminary judgment stage is that the number of potential pollution sources output by the source identification stage is greater than one. This stage determines and / or builds wells in batches and analyzes water quality to obtain a pollution concentration spatial distribution map, which is used to determine suspected pollution sources. The "suspected pollution source" refers to a potential pollution source that has a clear correlation with the abnormal area of pollution concentration or pollution plume distribution in spatial distribution, which is used to further narrow the range of actual pollution sources. If only one suspected pollution source corresponding to the pollution plume is identified by comparing the pollution concentration spatial distribution map with the potential pollution source spatial distribution map, for example, only the potential pollution source numbered 1 completely overlaps with the independent pollution plume, the present embodiment directly converts the suspected pollution source into the actual pollution source and terminates the tracing process. If multiple suspected pollution sources are identified or the pollution plume distribution appears to be continuous, the source corroboration stage is automatically entered.

[0058] In the present embodiment, the entering condition of the source corroboration stage is that the source preliminary judgment stage cannot directly determine the unique actual pollution source. At least two of water chemical analysis, isotope tracing analysis, numerical simulation tracing analysis and tracer tracing analysis are used for corroboration in the stage. The "corroboration consistency" refers to that different tracing technologies point to the same suspected pollution source or the same suspected pollution source set, and its function is to build an evidence chain of multi-technology cross-validation. For example, when water chemical analysis and isotope tracing analysis both point to the suspected pollution source numbered 2, the present embodiment determines that the suspected pollution source is the actual pollution source and terminates the tracing process; if there is no two or more technologies pointing to the same tracing conclusion, the tracer tracing analysis is entered as the final determination basis.

[0059] Through the setting of the above stage triggering and exit conditions, the present embodiment forms a "result-driven" process control mechanism for the groundwater copper and nickel pollution tracing process, that is, the output result of each stage directly determines whether the subsequent work is carried out. For example, in the case where the number of potential pollution sources is 1, the source preliminary judgment and source corroboration stages are no longer started, thereby avoiding unnecessary well construction and high-cost analysis; when there are multiple suspected pollution sources but two corroboration technologies have formed a consistent conclusion, the tracer tracing analysis is no longer performed, thereby reducing the disturbance to the production environment. The stage scheduling mechanism ensures that the tracing process can obtain a clear, reviewable and implementable tracing conclusion under different complexity scenarios.

[0060] Specifically, the overall tracing flowchart of the present embodiment can be seen from Figure 2 The specific process of the technical route of the present embodiment is as follows:

[0061] (I) Source identification stage

[0062] The main purpose of potential pollution source identification is to identify the possible potential pollution sources that may cause nickel and copper indicators to exceed the standard in the area to be traced, evaluate the possibility of human causes, and list them in the key attention area as far as possible based on the existing investigation data without increasing the engineering workload. The source identification stage can be generally divided into the following steps:

[0063] Step one: identification of pollution key indicators

[0064] The indicators to be traced are heavy metal indicators such as copper and nickel, and the exceeding amount is determined. According to GB / T 14848-2017, more than IV class (copper is 1.5 mg / L; nickel is 0.1 mg / L) is pollution, and more than 10 times of IV class (i.e., copper is 15 mg / L; nickel is 1 mg / L) is serious pollution.

[0065] Determine the area where the copper, nickel and other heavy metals exceed the standard as the pollution area, which does not point to a specific area, but only as the center position for subsequent tracing work.

[0066] Step two: determine the scope of pollution tracing

[0067] Because the flow of groundwater is not affected by artificial boundaries such as administrative regions or enterprise boundaries, the scope of tracing is mainly determined by the flow capacity of groundwater. By collecting hydrogeological survey data of the pollution area, the upstream and downstream relationship of the groundwater in the pollution area is preliminarily determined. First, according to the boundary of the smallest hydrogeological unit of the pollution area, the preliminary pollution tracing range is circled; if the area circled is too large, the range needs to be further reduced according to Darcy's law (Formula 1).

[0068] Formula 1

[0069] Where K is the average permeability coefficient of the region, which can be given based on the regional hydrogeological data; J is the hydraulic gradient, which can be given based on the regional hydrogeological data, or take the common hydraulic gradient of 2 ‰ if there is no data; t is the migration and diffusion time, which can be determined according to the time of regional land use, or take 5000 days if there is no data.

[0070] Tracing work is the tracing and investigation of existing pollution, so the upstream direction of groundwater should be taken as the main direction of investigation. The calculated pollution migration distance L is taken as the farthest upstream investigation distance determined by this patent, and if the upstream and downstream relationship of the pollution area cannot be determined, the pollution tracing needs to be extended around the pollution area in all directions.

[0071] Step three: identification of potential pollution sources

[0072] Based on the determined tracing range, collect data. Based on regional satellite pictures, historical image maps, etc., collect land use history data since farmland within the tracing range. Data collection work is divided into two steps: preliminary screening and key screening, and screening lists are established respectively.

[0073] a. For preliminary screening, combine relevant data such as pollution census and regional planning to sort out existing potential pollution sources within the tracing range, and form a preliminary screening list for pollution tracing. The preliminary screening list should include the spatial location of potential pollution sources (enterprises) within the tracing area, main production process / raw and auxiliary materials, production scale, etc.

[0074] b. For key screening, on the basis of establishing the preliminary screening list, enterprises or human activities that can cause potential pollution of heavy metals such as copper and nickel should be the focus of screening, and EIA data collection should be carried out for enterprises above designated size, and the enterprises or human activities involved in the land use in the whole time period (t) in the traceability area should be basically found out. The final time and space sequence pollution traceability key screening list should include: (1) potential pollution source code, (2) potential pollution source name, (3) potential pollution source spatial location, (4) information such as the way of copper and nickel pollution caused by potential pollution sources. Among them, the potential pollution mode should include the estimated maximum pollution leakage amount, the estimated pollution leakage path, the estimated pollution leakage position, the longest pollution duration and other information.

[0075] For the areas where the village and town level industrial cluster land use is not standardized, the history is long, and other objective reasons, it is difficult to identify the enterprises in a specific time period and the human activities in the area, which should be marked and included in the key screening list at the same time, and identified in the subsequent traceability stage. For the data with contradictions or unclear logic chain and the image area with large changes, personnel interviews should be carried out to verify the accuracy of the collected data.

[0076] Step four: Pollution possibility analysis

[0077] Combined with the hydrogeological conditions identified at this stage and the EIA data collected, the "source-path-receptor" whole chain pollution potential evaluation is carried out, and the marked sources in the key screening list are identified one by one.

[0078] Firstly, combined with the pollution leakage prevention condition, the pollution possibility (source) is evaluated, and the enterprises and human activity areas with clear anti-leakage measures are excluded as pollution sources for subsequent possibility analysis; for enterprises and related areas that cannot be clearly excluded from the leakage risk according to the existing data and field investigation, they are included in the further identification in the follow-up.

[0079] Secondly, on the basis of leakage prevention condition identification, combined with hydrogeological conditions, the pollution possibility (path) is evaluated. For the pollution areas and their traceability range with rich groundwater investigation and hydrogeological data, if the groundwater flow direction can be clearly determined, the copper and nickel pollution suspicion of the enterprises and human activity areas downstream of the traceability range can be excluded, and only the enterprises and human activity areas upstream and on both sides of the traceability range of the pollution area are further used as the objects of pollution possibility analysis; if the groundwater flow direction cannot be clearly determined, further investigation should be carried out for the enterprises and human activity areas in all directions of the pollution area in the traceability range.

[0080] Finally, on the basis of the existing hydrogeological condition discrimination, combined with the pollution degree of the pollution area, the pollution possibility (receptor) is evaluated. For the traceability scenario that can be calculated according to the pollution concentration, the pollution area range, etc. (generally corresponding to a certain investigation-based traceability condition), the maximum pollution level can be estimated in combination with the maximum pollution leakage estimation, the pollution leakage path estimation, the pollution leakage position estimation, the longest pollution duration estimation, etc. The difference between the maximum pollution level and Q is determined to determine whether the target enterprise or the human activity area has the potential to cause the same level of pollution. When the proportion of the maximum pollution level exceeds 10% of Q, it is considered to have pollution potential; when it is less than 10%, it is considered not to have pollution potential. For the traceability scenario that cannot be calculated according to the pollution concentration, the pollution area range, etc. (generally corresponding to no investigation-based traceability condition), further traceability work in the subsequent stage is required for further discrimination.

[0081] Formula 2

[0082] Wherein, Q is the total amount of pollutants; C is the average concentration of pollutants; Ω is the pollution area range; n is the porosity.

[0083] In this embodiment, whether the total amount of pollutants can be estimated according to the pollution concentration and the pollution area range belongs to the routine engineering judgment in groundwater pollution investigation, and the judgment is usually based on the completeness of the existing monitoring data. When the spatial boundary of the pollution area can be reasonably circumscribed through the monitoring well data or the investigation data, and the monitoring results of the pollutant concentration are representative and can reflect the overall condition of the pollution area, it is considered that the calculation of the total amount of pollutants according to the pollution concentration and the pollution area range is provided; otherwise, when the pollution area boundary cannot be closed, the monitoring data is insufficient, or the pollution is historical cumulative pollution and is difficult to trace back, it is considered that the above calculation conditions are not provided.

[0084] According to the enterprises or human activity areas screened according to the above step, the spatial distribution map of the potential pollution sources including the pollution area is drawn according to the center coordinates of the enterprises or human activity areas in the list. If there is only one enterprise or human activity area in the list, it is determined that the enterprise or the area is the determined actual pollution source, and the traceability process is ended; if there are multiple enterprises or human activity areas in the list, further preliminary determination of suspected pollution sources needs to be carried out.

[0085] Exemplarily, in the present embodiment, in order to make the "source-path-receptor" pollution possibility analysis verifiable and executable, without changing the existing screening list and criteria, the analysis is refined into a quantitative grading mechanism of "score item-score result-pollution possibility level". In the present embodiment, the "pollution possibility level" is defined as the grading determination result of the possibility of the potential pollution source causing the copper and nickel pollution of the groundwater, and its function is to provide a unified basis for the subsequent suspected pollution source locking and well priority. The score item is derived from the data types and judgment elements used in the present embodiment, including the information of the anti-leakage conditions obtained from the EIA data and the field investigation, the information of the upstream and downstream relationship of the groundwater obtained from the hydrogeological investigation data, and the information of the cases that the total amount of the pollutants can or cannot be calculated based on the pollution concentration and the pollution area range; the score is only used for standardized expression, without adding new monitoring indicators or new technical routes.

[0086] In the present embodiment, the "source" dimension is used to reflect whether the potential pollution source has the basic conditions to cause copper and nickel to enter the groundwater system, and the score item thereof at least includes the completeness of the anti-leakage measures and the leak risk exclusion. The data source of the completeness of the anti-leakage measures is the EIA data, the construction data of the production and storage areas of the enterprise, and the field reconnaissance records; and its function is to determine whether the potential pollution source has a possible path to leak into the ground. When the data can clearly determine that the enterprise or the human activity area has effective anti-leakage measures and can exclude the risk of leakage, the present embodiment determines that the object in the "source" dimension is low risk and can be directly excluded from the subsequent key analysis objects; when the data is incomplete or the field conditions cannot exclude the risk of leakage, the present embodiment determines that it is high risk and is retained for subsequent analysis. For example, if the potential pollution source 1 can provide complete construction and acceptance records of the anti-seepage structure and no damaged leakage signs are found on site, the present embodiment determines that the potential pollution source 1 in the "source" dimension is low risk; if the potential pollution source 2 lacks anti-seepage data and there is a suspected leakage point on site, the present embodiment determines that the potential pollution source 2 in the "source" dimension is high risk.

[0087] In the present embodiment, the "pathway" dimension is used to reflect the groundwater migration accessibility of the pollutants from the potential pollution source to the pollution area, and the scoring items thereof at least include whether the groundwater flow direction is clear and the spatial position relationship of the potential pollution source relative to the pollution area. The data source of the groundwater flow direction information is the hydrogeological investigation data and the regional groundwater data, which functions to determine the main direction of the tracing investigation and to exclude or reduce the weight of the downstream objects. When the groundwater flow direction is clear, the present embodiment directly determines the enterprises or human activity areas located downstream of the pollution area as low correlation objects, thereby reducing invalid investigation; when the groundwater flow direction is not clear, the present embodiment keeps focusing on the objects upstream and on both sides of the pollution area, and temporarily does not exclude the objects in all directions for subsequent stage screening. For example, if the data shows that the main groundwater flow direction is from west to east, then the potential pollution source 3 located on the east side of the pollution area and downstream is determined as a low correlation object in the present embodiment; if the flow direction cannot be determined, then the potential pollution source 3 is not directly excluded, but the "pathway" dimension determination result thereof will be marked as uncertain, so as to prompt that subsequent further verification is needed through the source preliminary determination stage.

[0088] In the present embodiment, the "receptor" dimension is used to reflect the matching degree of the current pollution scale caused by the potential pollution source, and the scoring items include at least whether the total amount of pollutants can be calculated, and the proportion criterion of the maximum pollution level to the total amount of pollutants. The information source of whether the total amount of pollutants can be calculated is the pollution area monitoring data and the pollution area range data, which functions to judge whether there is a basis for carrying out "magnitude comparison determination"; when the calculation condition is not met, the present embodiment does not make a negative conclusion on the proportion of the maximum pollution level to the total amount of pollutants, but determines the "receptor" dimension of the object as to be verified, and keeps it entering the subsequent stage. For the case with calculation condition, the present embodiment uses the existing proportion criterion: when the maximum pollution level accounts for more than one tenth of the total amount of pollutants, it is determined to have pollution potential; when it is less than one tenth, it is determined to have no pollution potential. Further, in order to realize the grading linkage with the pollution degree, the present embodiment takes the "pollution degree" as the rule shunting basis, and the data source of the pollution degree is the determination result of the copper and nickel exceeding standard degree in the pollution key indicator identification step of the present embodiment according to the groundwater environmental quality standard, which functions to determine the influence weight of the "receptor" dimension conclusion on the overall grade: when the pollution area is determined to be seriously polluted, the present embodiment gives higher priority to the conclusion of "more than one tenth" for preferentially locking the suspected pollution source; when the pollution area is determined to be generally polluted, the present embodiment still uses the proportion criterion, but allows the objects with less than one tenth of the proportion and both "source and pathway" being low risk to be preferentially excluded, so as to reduce the investigation cost. For example, if the pollution area is determined to be seriously polluted, and the maximum pollution level of the potential pollution source 4 accounts for more than one tenth, the present embodiment determines the "receptor" dimension of the potential pollution source 4 as high matching and preferentially enters the suspected pollution source; if the pollution area is generally polluted, and the potential pollution source 5 accounts for less than one tenth, and it has anti-leakage measures and is located downstream, the present embodiment determines the potential pollution source 5 as low possibility and excludes it from the key objects.

[0089] In this embodiment, the pollution possibility level is formed by the determination results of the three dimensions of "source, path, receptor", and is output to the key screening list in the form of a level, which is used as the basis for drawing the spatial distribution map of potential pollution sources and determining suspected pollution sources. In order to avoid unclear description, the meaning of the pollution possibility level is defined as follows in this embodiment: a high level indicates that at least two dimensions of "source, path, receptor" are high risk or high matching; a medium level indicates that one dimension is high risk or high matching and the other dimensions are uncertain or general; and a low level indicates that the "source" can be excluded from the leakage risk or the "path" is definitely downstream and the "receptor" does not have pollution potential. The function of the level is to provide a reviewable ranking basis for "potential pollution source screening to obtain potential pollution sources and draw a spatial distribution map", and to guide the source preliminary judgment stage to preferentially carry out geophysical method determination or preferentially arrange the tracing well. For example, when the potential pollution source 6 is high risk in the "source" dimension, high correlation in the "path" dimension, and to be verified in the "receptor" dimension, this embodiment determines it as a medium level and includes it in the subsequent verification; when the potential pollution source 7 is low risk in the "source" dimension and low correlation in the "path" dimension, even if the "receptor" dimension is to be verified, this embodiment determines it as a low level and reduces its priority, so as to realize the controllable balance between accuracy and cost in the tracing work.

[0090] (ii) Source preliminary judgment stage

[0091] The suspected pollution source preliminary judgment stage is mainly based on the foregoing potential pollution source identification, and further traces the pollution by carrying out additional work. The source preliminary judgment stage mainly carries out indirect or direct observation on the groundwater quality by carrying out non-invasive exploration such as geophysical method, a certain number of monitoring well construction and water quality analysis. By identifying the spatial distribution characteristics of nickel and copper indicators, the spatial relationship with the suspected pollution source is established, and the pollution tracing is finally realized.

[0092] Step one: Geophysical method determination

[0093] When the pollution area belongs to serious pollution, and there is no underground pipeline restriction in the tracing range, the geophysical method can be applied to carry out the tracing determination. Based on the potential pollution sources determined in the source identification stage, high-density resistivity method is carried out in the direction of the connecting line of the potential pollution sources and the pollution area and the vertical direction thereof. The geophysical method (such as high-density resistivity method) is generally suitable for the tracing of the investigation area with relatively clear pollution path and relatively clear position of potential pollution source. In actual application, combined with various geophysical exploration means such as direct current resistivity method (DC), very low frequency electromagnetic method (VLF-EM), transient electromagnetic method (TEM), induced polarization method (IP), ground penetrating radar (GPR), shallow seismic reflection, well CT (cross-hole resistivity imaging method), and combined with hydrogeological data verification, the above defects can be compensated to a certain extent, and the accuracy and reliability of the interpretation are improved.

[0094] The geophysical method includes project design and field layout, data acquisition and preprocessing, inversion modeling, result interpretation and report preparation. By inverting and depicting the resistivity in the survey area, the potential pollution sources and the internal correlation of the tracing area are identified, and then the pollution tracing is realized.

[0095] a. Project design and field layout: Determine the tracing area and range, design the electrode layout scheme, select appropriate electrode spacing and number. Arrange the electrodes on the ground according to the designed scheme, usually in a straight line or grid shape, and connect the electrodes to the resistivity measuring instrument.

[0096] b. Data acquisition and preprocessing: Use high-density resistivity measuring instrument to automatically switch electrode connection and conduct resistivity measurement. Collect resistivity data under different electrode combinations to form resistivity profile. Clean up data and exclude abnormal values such as false readings caused by poor contact or electrode damage. Normalize the data to eliminate the influence of measurement condition changes.

[0097] c. Inversion modeling: Use resistivity data for numerical inversion to reconstruct two-dimensional or three-dimensional models of underground resistivity distribution. Use professional geophysical software for inversion calculation to obtain the distribution map of underground resistivity.

[0098] d. Result interpretation and report preparation: Interpret the resistivity distribution map, analyze the flow path of groundwater, the distribution of aquifer and the possible location of pollution sources. Combine with hydrogeological data to infer the groundwater pollution sources in the resistivity anomaly area. Write the exploration report including exploration purpose, method, result and conclusion. Prepare related drawings such as resistivity profile, two-dimensional or three-dimensional resistivity distribution map, etc.

[0099] By superimposing and comparing the interpreted resistivity spatial distribution map with the potential pollution source spatial distribution map, if there is a spatial overlap between the resistivity spatial anomaly area and the potential pollution source, and the corresponding migration path can be observed, it indicates that the potential pollution source has a strong pollution correlation and can be used as the focus of the next step of well construction and source tracing.

[0100] When the pollution area is not severely polluted, or there are underground pipelines in the tracing range, geophysical method may not be used for tracing.

[0101] Step two: Build wells in batches and analyze water quality

[0102] Based on the potential pollution sources identified in the source identification stage, combined with the groundwater flow direction in the tracing range, around the pollution area (such as Figure 3The first batch of traceability well layout is carried out around the pollution monitoring well (as shown by the identification of the pollution monitoring well). If the groundwater flow direction is clear, the pollution sources downstream of the groundwater do not need to carry out traceability well layout (as shown by directions C and D, which can not be laid out); if the groundwater flow direction is not clear, all potential pollution sources identified by source identification need to carry out the first batch of layout. Figure 3

[0103] a. First batch of well construction: The first batch of traceability wells should be laid around the pollution area in principle, and the purpose is to identify the direction of the pollution source and its relevance to the potential pollution source through pollution overlay analysis. The first layout should follow: ① The traceability well layout position should be as possible as in the middle position between the pollution area (pollution monitoring well) and the potential pollution source; ② The number of traceability well layout should not be less than the number of potential pollution sources identified in the source identification stage; ③ The depth of traceability well layout can be adjusted appropriately according to the preliminary investigation of groundwater or the regional groundwater depth condition, on the basis of meeting the same groundwater aquifer as the pollution area.

[0104] If the regional geological conditions are complex, there are multiple sets of groundwater aquifers, and the pollution monitoring well of the pollution area where the traceability work is to be carried out belongs to mixed layer monitoring, the traceability well construction and monitoring work should be carried out in layers to identify the specific pollution layer. If limited by in-production buildings and existing objective conditions, the first layout position can be adjusted appropriately, but the adjusted position still needs to meet the purpose of the first batch of well construction.

[0105] After the well construction is completed, water sample collection and analysis of groundwater quality characteristic indicators such as copper and nickel are carried out. For pollution areas with multiple sets of groundwater aquifers and pollution monitoring wells belonging to the string layer type, groundwater copper and nickel indicators need to be monitored for each layer. The pollution concentration spatial distribution map obtained by the monitoring results is compared with the potential pollution source spatial distribution map, if there is only one high concentration detection result (as shown by the detection of pollution in only one traceability well), the potential pollution source can be directly locked as a suspected pollution source, and the second batch of well construction is skipped. If the monitoring results indicate that there are not unique concentration detections (as shown by the detection of pollution in multiple traceability wells), the second batch of traceability well construction needs to be further carried out. Figure 3 Figure 3

[0106] If there is a dense pollution concentration spatial distribution, which makes it impossible to directly determine whether there is an overlay with the potential pollution source spatial distribution, the first moment calculation formula (formula 3) can be used to determine the center position of the pollution concentration spatial distribution, and then the distance difference from the potential pollution source is used to judge the relevance of the potential pollution.

[0107] Formula 3

[0108] Where: is the center of mass in​​​ coordinates in the direction of X (e.g. is the X coordinate, is the Y coordinate); is the zeroth moment (total mass), ; is the concentration at the location and time ; is the coordinate value in the direction of X; is the coordinate value in the direction of Y; is the entire calculation area.

[0109] b. Second batch of wells: On the basis of the first batch of well screening, the second batch of well layout work is supplemented. According to the monitoring results of copper and nickel concentration in the first batch of layout, further screening of potential pollution sources that need to be focused on is carried out, and the second batch of points is carried out around the enterprises or human activities area that appear strong pollution association in the first layout. Further clarify the number of suspected pollution sources (as shown in Figure 4 , assuming that there is pollution detection in the middle part of the connection line between A and B and the pollution area).

[0110] The purpose of the second batch of well layout is to basically determine the number of suspected pollution sources in the source tracing range that cause pollution, and further consider the identification of pollution channels. Specifically: ① The location of the source tracing well should be around the high correlation potential pollution source identified in the first batch of well layout; ② The number of source tracing wells should meet the control of the main direction of pollution migration and diffusion, and the groundwater flow direction should be referred to, and the downstream of the potential pollution source and the upstream of the pollution area should be focused on; ③ The depth of the source tracing well can be adjusted to the source pollution layer based on the first batch of source tracing conclusion.

[0111] After the second batch of wells is completed, water sample collection and analysis of groundwater quality characteristic indicators such as copper and nickel are carried out. On the basis of basically locking the pollution layer in the first batch of well layout, analysis is mainly carried out for the pollution layer. Because the interval between the batches of well layout is relatively short, the pollution concentration spatial distribution map can be drawn by taking the detection data of the two batches, and compared with the spatial distribution map of potential pollution sources.

[0112] If there is only one and independent pollution plume distribution, the potential pollution source overlapping with the pollution plume will be converted into an actual pollution source, and the source tracing work will be ended; if there is a continuous pollution plume distribution, all potential pollution sources within the pollution plume distribution range will be converted into suspected pollution sources, and the next stage of actual pollution source evidence work will be carried out.

[0113] (Three) Source evidence stage

[0114] In view of the complex production activities and underground environment of the village and town level industrial cluster area, for the situation that the actual pollution source cannot be directly identified after completing the foregoing traceability stage work, the pollution source will be further evidenced to strengthen the accuracy and reliability of the traceability conclusion. The source evidence stage mainly depends on the characteristics of copper, nickel and other indicators to indicate the same traceability conclusion by coupling multiple technical means to improve the traceability accuracy.

[0115] The patent adopts groundwater hydrochemistry analysis, isotope traceability, numerical simulation method and groundwater tracer method as source evidence technology. The above-mentioned technologies are friendly to copper and nickel index traceability, and the time and economic cost increases in turn; if more than two technologies point to the same traceability conclusion in the source evidence stage, the traceability work can be ended; if there is no more than two technologies pointing to the same traceability conclusion, the foregoing traceability stage result needs to be further verified.

[0116] If the foregoing traceability stage result is correct, the conclusion obtained by the groundwater tracer method is the final traceability conclusion.

[0117] Technology one: groundwater hydrochemistry analysis

[0118] Groundwater chemical analysis includes sample collection and detection, result interpretation and other steps. By calculating the groundwater chemical characteristics of potential pollution sources and the area to be traced, the internal correlation of potential pollution sources and the area to be traced is identified, and then the pollution traceability is realized. The precondition for using water chemistry to trace pollution is that the existing pollution has affected the water chemistry type.

[0119] a. Sample collection and detection: by collecting groundwater samples in the monitoring wells of the investigation area, the concentration of eight ions and the total dissolved solids value are measured; then, the measured ion concentration of each type is used to visually display the water chemistry type and the type of water-rock interaction by using Piper tri-graph, Gibbs graph and other graphical tools;

[0120] b. Result interpretation: by analyzing the spatial position correlation between the area to be traced and the potential pollution source area, the calculated groundwater chemistry type is placed on the spatial plane according to the monitoring well position, and the same groundwater chemistry type as the pollution area is circled to assist in determining the pollution source.

[0121] For the situation that there are multiple suspected pollution sources, if the water chemistry type around a suspected pollution source A is consistent with the pollution area and is different from other suspected pollution sources, the traceability result of this technology points to A as the actual pollution source; if multiple suspected pollution sources are consistent with the pollution area, this technology cannot directly point to the actual pollution source, and needs to be further cooperated with the subsequent source evidence traceability technology for traceability.

[0122] Technology two: multiple isotope traceability analysis

[0123] Isotope tracing analysis includes sample collection and detection, result interpretation, etc. By analyzing the key isotope composition of suspected pollution sources and the region to be traced, the internal correlation of suspected pollution sources and the region to be traced is identified, and then pollution tracing is realized. Isotope tracing has more excellent effect in dealing with non-uniform monitoring well layout conditions of village-level industrial cluster area compared with groundwater hydrochemistry analysis.

[0124] a. Sample collection and detection: By collecting groundwater samples of monitoring wells in the investigation area, surface water and wastewater samples of suspected pollution enterprises and human activity areas, isotope analysis is carried out to quantitatively focus on the isotope composition. The key isotope to be analyzed includes radon isotope, hydrogen and oxygen isotope commonly found in groundwater, and other element isotopes related to pollutants such as copper and nickel in the foregoing tracing stage. If necessary, copper and nickel isotopes can also be directly used for tracing analysis.

[0125] b. Result interpretation: Based on the spatial correlation between the region to be traced and the potential pollution source region, the determined isotope ratio is compared with the isotope characteristics of known groundwater recharge sources or pollution sources to identify the pollution source.

[0126] For the scenario of multiple suspected pollution sources, if the isotope composition characteristics around a suspected pollution source A are consistent with the pollution region, and different from other suspected pollution sources, the result of the present technology points to A as the actual pollution source; if multiple suspected pollution sources are consistent with the pollution region, the present technology cannot directly point to the actual pollution source, and further combined with subsequent groundwater numerical simulation tracing technology, collaborative tracing analysis based on multiple pollution sources mixed pollution needs to be carried out.

[0127] Technology three: groundwater numerical simulation tracing analysis

[0128] Groundwater numerical simulation includes hydrogeological model construction, numerical simulation model construction, pollutant transport simulation and prediction, potential pollution source correlation analysis, etc. By comparing and analyzing the actual pollution plume and the simulated pollution plume, the internal correlation of potential pollution sources and the region to be traced is identified, and then pollution tracing is realized.

[0129] a. Hydrogeological model construction: Based on borehole data, the stratum structure, recharge and discharge conditions, related parameter distribution, numerical simulation constitutive equation, etc. of the investigation area are described;

[0130] b. Numerical simulation model construction: Based on the hydrogeological model, the groundwater numerical simulation model is constructed, and the model is verified based on the measured groundwater level and water quality data;

[0131] c. Contaminant transport simulation and prediction: Based on the established and verified numerical simulation model, combined with potential pollution sources and their possible pollution conditions, numerical simulation prediction is carried out;

[0132] d. Correlation analysis of potential pollution sources: According to the numerical simulation results of potential pollution sources, the correlation between simulated pollution plume and actual pollution plume in spatial distribution is analyzed, and the correlation of potential pollution sources is analyzed.

[0133] The numerical simulation model is mainly based on the constitutive equation (formula 4 and 5).

[0134] Formula 4

[0135] Where h is the water head; t is the time; x, y, z are spatial coordinates; K xx ,K yy ,K zz is the permeability coefficient in the main direction; S is the storage coefficient; W is the source and sink term.

[0136] Formula 5

[0137] Where C is the solute concentration; t is the time; D ij is the hydrodynamic dispersion coefficient tensor; v i is the average actual flow rate of pore water; q s is the unit volume flow rate of source and sink term; C s is the solute concentration of source and sink term; θ is the porosity; ΣRn is the chemical reaction term.

[0138] For multiple suspected pollution source scenarios, numerical simulation is carried out with each suspected pollution source as a hypothetical pollution leakage source. If the pollution plume area of a suspected pollution source A in a time period (t) is basically consistent with the pollution concentration spatial distribution map constructed by the well in the same stage, and there is no overlap with the pollution plume distribution map of other suspected pollution sources, the technical result points to A as the actual pollution source; If the pollution plumes of multiple suspected pollution sources overlap, it indicates the possibility of multiple source pollution, which can be combined with isotope data calculation to confirm or exclude the phenomenon of mixing of multiple suspected pollution sources.

[0139] Technology four: groundwater tracer tracing analysis

[0140] Groundwater tracer tracing includes tracer selection, migration and diffusion monitoring, result interpretation and other steps. By directly depicting the migration process of the tracer, the internal correlation of the potential pollution source and the proposed source tracing area is identified, and then the pollution source tracing is realized. By monitoring the groundwater in the wells within the investigation area, a specific, detectable tracer or marker is added to accurately track the flow direction of the groundwater. These tracers can be naturally occurring or artificially added (for example, by adding Sudan red, chloride ion, fluorescent agent, etc. Tracers). By collecting water samples at different times and places and analyzing the concentration and distribution of tracers, the flow characteristics of groundwater can be inferred, including flow rate, flow direction, flow path, and water mixing and exchange process.

[0141] a. Tracer selection: Select appropriate tracers according to the pollution type, migration and diffusion ability, groundwater quality management requirements of the investigation area, and start betting around the potential pollution source.

[0142] b. Migration and diffusion monitoring: Conduct tracer sampling and concentration monitoring, analysis in other monitoring wells in the investigation area, and record the pollution migration and diffusion time. If necessary, new wells and tracer sampling are added along the pollution migration and diffusion path to finely depict the tracer migration channel.

[0143] c. Result interpretation: Based on the tracer migration and diffusion results, the migration and diffusion path of the existing pollution is inverted, the groundwater flow velocity and age are inferred, and the pollution source tracing is realized.

[0144] The suspected pollution source determined by the groundwater tracer tracing method is the real pollution source causing the pollution.

[0145] By integrating and analyzing the conclusions of various source corroboration techniques in the source corroboration stage, the final source tracing conclusion is obtained, which has the following three possibilities: (1) Two or more methods clearly specify a suspected pollution source as a real pollution source; (2) Isotope source tracing method and numerical simulation method specify that there are multiple suspected pollution sources mixed to form a real pollution source; (3) Groundwater tracer tracing method indicates a single real pollution source or multiple real pollution sources.

[0146] Further, after the foregoing several stages of source tracing work, the pollution leakage enterprise or the area of human activities can be basically determined, and the subsequent pollution range delineation work of the actual pollution source can be carried out.

[0147] On the basis of building wells in batches, build wells and delineate pollution sources around a single or multiple actual pollution sources (as shown in Figure 5 , the monitoring well layout in the delineation process should be around the actual pollution source and the pollution area). If the proposed site area does not meet the site requirements due to the existence of producing enterprises and buildings, the site location can be adjusted appropriately and the delineation range can be appropriately expanded (as shown in Figure 5Detailed investigation is carried out on potential pollution source A as shown.

[0148] At this point, all the tracing work is completed, and the determined pollution boundary is used as the basis for subsequent processing.

[0149] The beneficial effects of the present application are as follows:

[0150] (1) The present application constructs a phased tracing process of "source identification-source preliminary judgment-source corroboration", and allows skipping the subsequent stage when the stage judgment condition is met, so that the tracing work is gradually promoted from data integration, spatial correlation to evidence closed loop, realizing the systematic and implementable identification of the source of groundwater copper and nickel pollution in the village and town industrial cluster area, and improving the explainability and consistency of the tracing conclusion.

[0151] (2) The present application restricts the tracing range by the minimum hydrogeological unit boundary and the pollution migration distance calculated by Darcy's law, changes the investigation boundary from the administrative / enterprise boundary to the "farthest upstream investigation distance" in the hydrogeological sense, reduces the indiscriminate expansion investigation, and improves the scientificity and reproducibility of the tracing range.

[0152] (3) The present application realizes the hierarchical screening and priority sorting of potential pollution sources by constructing "preliminary screening list-key screening list", and introducing "source-path-receptor" pollution possibility analysis and maximum pollution level and pollution total amount proportion threshold criterion, avoiding the missed judgment and misjudgment caused by enterprise distribution or experience judgment, and improving the accuracy of potential pollution source identification.

[0153] (4) When there are multiple potential pollution sources, the present application combines geophysical non-invasive exploration and batch well construction water quality analysis, uses the overlay comparison of pollution concentration spatial distribution map and potential pollution source spatial distribution map to gradually lock the suspected pollution source, and when necessary, determines the pollution center position by the first moment to assist in judging the relevance, so that the tracing path still has implementability and stability under complex conditions such as spatial limitation and staggered production.

[0154] (5) The present application introduces the coupling mechanism of multiple technologies such as water chemistry, isotope, numerical simulation and tracer in the source corroboration stage, takes "more than two technologies pointing to the same tracing conclusion" as the evidence convergence rule, and takes tracer tracing as the final bottom-up conclusion source, so as to form a verifiable and reproducible evidence chain, and significantly improve the reliability of the tracing conclusion and the support ability of responsibility identification.

[0155] Each embodiment in the specification is described in a progressive manner, and each embodiment focuses on the difference from other embodiments.

[0156] The principles and implementation manners of the present application are described by using specific examples in the present application, and the above examples are only used to help understand the method of the present application and its core idea; meanwhile, for the general technical personnel in the art, the specific implementation manners and application ranges will be changed according to the idea of the present application. In conclusion, the content of the present specification should not be understood as the limitation of the present application.

Claims

1. A method for tracing the source of copper and nickel pollution in groundwater in village and town-level industrial clusters, characterized in that, Under the condition that groundwater pollution source tracing is initiated, the process shall be carried out in the following order: source identification, initial source assessment, and source evidence verification, including: The proposed source tracing indicators were determined to be copper and nickel, and the degree of exceeding the standards was assessed to identify the polluted areas. Collect hydrogeological data of the polluted area, delineate the preliminary range based on the boundary of the smallest hydrogeological unit, and calculate the pollution migration distance based on the preliminary range and Darcy's law to determine the source range; Collect land use history and potential pollution source data within the aforementioned source tracing area, and establish a preliminary screening list and a key screening list; A "source-pathway-receptor" contamination probability analysis was conducted on the key screening list to identify potential pollution sources and draw a spatial distribution map. If only a single potential pollution source exists, it is determined to be an actual pollution source. If multiple potential pollution sources exist, geophysical methods are used to determine and / or wells are constructed in batches and water quality analysis is conducted to obtain a spatial distribution map of pollution concentration, and suspected pollution sources are identified by comparing the overlay maps. If the actual pollution source still cannot be directly identified, at least two of the following methods should be used for corroboration: water chemical analysis, isotope source tracing analysis, numerical simulation source tracing analysis, and tracer tracer source tracing analysis. If two or more techniques point to the same source tracing conclusion, the process ends; otherwise, the tracer tracer source tracing analysis conclusion shall be used as the final source tracing conclusion.

2. The method for tracing the source of copper and nickel pollution in groundwater in village and town-level industrial clusters according to claim 1, characterized in that, The conditions for initiating groundwater pollution source tracing include: Through the construction of groundwater environmental monitoring wells and water quality analysis, it was discovered that the water quality was deteriorating due to significant human factors; or During the extraction of groundwater for production activities, abnormal water quality leads to significant changes in the sensory characteristics of color and odor; or There is a possibility of groundwater contamination due to an emergency, and further investigation is needed.

3. The method for tracing the source of copper and nickel pollution in groundwater in village and town-level industrial clusters according to claim 1, characterized in that, The degree of exceedance is determined according to GB / T 14848-2017. Copper exceeding Class IV is considered pollution, and copper exceeding Class IV by more than 10 times is considered severe pollution. Nickel exceeding Class IV is considered pollution, and nickel exceeding Class IV by more than 10 times is considered severe pollution.

4. The method for tracing the source of copper and nickel pollution in groundwater in village and town-level industrial clusters according to claim 1, characterized in that, In calculating the pollution migration distance based on Darcy's Law, the permeability coefficient is given based on regional hydrogeological data, the hydraulic gradient is given based on regional hydrogeological data and is defaulted to 2‰, the migration and diffusion time is determined based on the regional land use time and is defaulted to 5000 days, and the pollution migration distance is taken as the farthest upstream investigation distance of the pollution.

5. The method for tracing the source of copper and nickel pollution in groundwater in village and town-level industrial clusters according to claim 1, characterized in that, The preliminary screening list includes the spatial location of potential pollution sources, main production processes or raw materials, and production scale; the key screening list includes the source code of potential pollution sources, the name of potential pollution sources, the spatial location of potential pollution sources, and the ways in which potential pollution sources cause copper and nickel pollution to groundwater.

6. The method for tracing the source of copper and nickel pollution in groundwater in village and town-level industrial clusters according to claim 1, characterized in that, The "source-pathway-receptor" contamination probability analysis includes: Based on pollution leakage prevention conditions, exclude enterprises or areas with human activity that have anti-leakage measures; When determining the direction of groundwater flow by combining hydrogeological conditions, exclude enterprises or areas of human activity downstream of the polluted area; For source tracing scenarios where the total amount of pollutants can be calculated based on pollution concentration and pollution area range, determine the proportion of the maximum pollution level to the total amount of pollutants; When the proportion exceeds 10%, it is considered to have pollution potential; when the proportion is less than 10%, it is considered to have no pollution potential.

7. The method for tracing the source of copper and nickel pollution in groundwater in village and town-level industrial clusters according to claim 1, characterized in that, The conditions for the geophysical method to determine the pollution are: the polluted area is severely polluted and there are no underground pipelines restricting the source tracing area.

8. The method for tracing the source of copper and nickel pollution in groundwater in village and town-level industrial clusters according to claim 1, characterized in that, The geophysical method used for identification employs the high-density resistivity method, which involves deploying and measuring data along the line connecting the potential pollution source and the polluted area, as well as in the vertical direction. The process of the geophysical method includes project design and site layout, data acquisition and preprocessing, inversion modeling, result interpretation, and report preparation.

9. The method for tracing the source of copper and nickel pollution in groundwater in village and town-level industrial clusters according to claim 1, characterized in that, The phased well construction and water quality analysis included: The first batch of wells will be constructed around the contaminated area, with the well locations situated between the contaminated area and potential pollution sources. The number of wells will be no less than the number of potential pollution sources, and the depth of the wells will be within the same aquifer as the contaminated area. If pollution is detected in only one well after monitoring is completed, the corresponding potential pollution source will be identified as a suspected pollution source, and the second batch of wells will be skipped. The second batch of wells were constructed around the highly relevant potential pollution sources identified in the first batch of wells. The number of wells was sufficient to control the main direction of pollution migration and diffusion, and they were mainly deployed downstream of potential pollution sources and upstream of pollution areas. The depth of the wells was adjusted to the pollution stratum.

10. The method for tracing the source of copper and nickel pollution in groundwater in village and town-level industrial clusters according to claim 9, characterized in that, After the second batch of wells is completed, the two batches of test data are used to draw a spatial distribution map of pollution concentration and overlay it with a spatial distribution map of potential pollution sources. If there is only one unique and independent pollution plume distribution, the potential pollution sources overlapping with the pollution plume will be converted into actual pollution sources, and the process of tracing the source of copper and nickel pollution in groundwater will be terminated. If there is a continuous pollution plume distribution, all potential pollution sources within the distribution range of the pollution plume will be converted into suspected pollution sources and enter the source verification stage.

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