A method for delineating the extent of a pollution plume using pollutants and their metabolites in soil.
By performing minimally invasive procedures at a depth of 50cm in the soil surface, and utilizing point layout, gas concentration collection, curve fitting, and interpolation methods, the problems of long time and high cost in the investigation of volatile organic pollution sites were solved, and rapid and convenient pollution plume delineation was achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- SUZHOU GUANFU ENVIRONMENTAL TECH CO LTD
- Filing Date
- 2023-03-27
- Publication Date
- 2026-06-30
AI Technical Summary
Existing investigations of sites with volatile organic pollution are time-consuming, costly, and cause significant environmental disturbance.
By employing point deployment, gas concentration collection, curve fitting, and interpolation methods, the underground gas concentration was detected at a depth of 50cm in the soil surface through minimally invasive procedures. The range of the pollution plume was delineated using curve fitting and interpolation methods.
It enables rapid and convenient delineation of the pollution plume range, significantly shortening the investigation time and cost, while reducing site disturbance.
Smart Images
Figure CN116413413B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of underground soil detection, and in particular to a method for delineating the range of a pollution plume using pollutants and their metabolites in the soil. Background Technology
[0002] During the diffusion of VOCs vapor from soil and groundwater to the surface, a series of biogeochemical reactions can occur, including mineralization, methanogenesis, and methane oxidation. This leads to anomalies in surface carbon dioxide and methane levels, and anomalies in surface oxygen levels. Under strong conditions of these reactions, VOCs may be consumed at the surface or even become undetectable. Non-volatile organic compounds also undergo a series of reactions, similarly exhibiting anomalies in surface carbon dioxide and methane levels and low oxygen levels. Therefore, using surface soil gases (VOCs, carbon dioxide, methane, O2, etc.) to detect underground organic pollution and delineate the extent of pollution plumes has broad application prospects.
[0003] In existing investigations of volatile organic compound (VOC) contamination sites, the most commonly used technique is drilling, which involves collecting samples from the vadose zone and aquifer at different depths and sending them to the laboratory for testing. This method is time-consuming and expensive. Summary of the Invention
[0004] To address the aforementioned technical problems, this invention provides a method for delineating the range of a pollution plume using pollutants and their metabolites in soil. This method solves the problems of slow delineation of pollution ranges, significant disturbance to the site environment, long detection time, and high costs.
[0005] To achieve the above objectives, the technical solution of the present invention is as follows:
[0006] A method for delineating the extent of a pollution plume using pollutants and their metabolites in soil includes:
[0007] The sampling points should be set up according to the needs of the site to be investigated;
[0008] Drill holes at the identified locations and use a detection device to collect and measure the gas concentration in the soil.
[0009] The collected gas concentration data were fitted using a curve fitting model. The cumulative probability curve was divided into intervals, and the optimal regression curve for each interval was analyzed and determined. Then, the intersection of the regression curves of two adjacent intervals in the cumulative probability curve was used as the threshold for partitioning.
[0010] Based on the zoning thresholds and using the interpolation method, a planar distribution map of each pollution indicator was drawn.
[0011] As a preferred embodiment of the present invention, the site to be investigated is laid out using one or more of the following methods in combination: systematic random point layout, professional judgment point layout, zonal point layout, systematic point layout, and square grid probability method, based on site differences.
[0012] As a preferred embodiment of the present invention, the distance between the points in the site to be investigated can be selected as 300-500m or 10-20m.
[0013] As a preferred embodiment of the present invention, the gas concentration detected above refers to the volatile organic compounds accumulated in the surface soil and the gas concentration of biological metabolism produced by biogeochemical reactions such as mineralization, methanogenesis, and methane oxidation during their diffusion to the surface.
[0014] As a preferred embodiment of the present invention, the biogeochemical reactions occurring during the diffusion of volatile organic compounds to the Earth's surface include, but are not limited to, mineralization, methanogenesis, and methane oxidation.
[0015] The bio-metabolic gases include, but are not limited to, CO2, O2, CH4, H2, H2S, HCHO, and NH3.
[0016] As a preferred embodiment of the present invention, based on the three-interval model theory of pollution source-source area-pollution plume, the cumulative probability curve is partitioned according to the principle of linear regression optimization.
[0017] As a preferred embodiment of the present invention, the interpolation method includes, but is not limited to, one of the following: Kriging interpolation, inverse distance weighted interpolation, natural neighbor interpolation, and nearest neighbor interpolation.
[0018] As a preferred embodiment of the present invention, the indicators delineated by the pollution plume range include, but are not limited to, VOCs, CO2, O2, CH4, H2, H2S, HCHO, and NH3.
[0019] In summary, the present invention has the following beneficial effects: by performing a minimally invasive operation on only about 50cm of the soil surface, it is possible to detect the concentration of relevant gases in the soil subsurface and quickly delineate the range of the pollution plume. The operation is simple and convenient, greatly reducing the time and cost of site investigation. Attached Figure Description
[0020] Figure 1 This is a schematic diagram of the method flow of the present invention.
[0021] Figure 2 This is a schematic diagram of the site sampling point layout according to the present invention.
[0022] Figure 3 This is a schematic diagram of the cumulative probability linear fitting results of the present invention.
[0023] Figure 4 This is a schematic diagram of the pollution plane distribution according to the present invention.
[0024] Figure 5 This is a schematic diagram showing the planar distribution of contamination at a depth of 50cm (left) and 150cm (right) during the drilling process for comparison in this invention. Detailed Implementation
[0025] To enable those skilled in the art to better understand the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings.
[0026] In some of the processes described in the specification, claims, and accompanying drawings of this invention, multiple operations appearing in a specific order are included. However, it should be clearly understood that these operations may not be performed in the order they appear herein, or may be performed in parallel. The operation numbers, such as 101, 102, etc., are merely used to distinguish different operations and do not themselves represent any execution order. Furthermore, these processes may include more or fewer operations, and these operations may be performed sequentially or in parallel.
[0027] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0028] Example 1
[0029] Please see Figure 1 This invention provides a method for delineating the extent of a pollution plume using pollutants and their metabolites in soil, comprising:
[0030] S100. Deploy survey points at the sites to be investigated as needed.
[0031] Specifically, based on site differences, one or more methods are combined, including systematic random sampling, professional judgment sampling, zonal sampling, systematic sampling, and square grid probability method, to determine the sampling points for the site to be surveyed. These methods include:
[0032] S101. For areas with similar soil characteristics and the same land use function within the site, a systematic random sampling method can be used to set up monitoring points.
[0033] S102. If the characteristics of site pollution are unclear or the original condition of the site is severely damaged, a systematic sampling method can be used to set up sampling points.
[0034] S103. For sites with different land use functions and significantly different pollution characteristics, the zoning method can be used to set up the sampling points.
[0035] S104. For plots of land with clearly defined potential pollution, the professional judgment and sampling method can be used to determine the location of sampling points.
[0036] The spacing between the site layout points shall be implemented according to the following conditions, specifically including:
[0037] S105. For the entire study area, the objective is to identify several pollution sources. It is recommended that the sampling points be spaced approximately 300-500m apart.
[0038] S106. For a specific pollution source, the purpose is to distinguish the pollution source area, plume, and background, with a sampling distance of approximately 10-20m.
[0039] S200. Drill holes at the determined deployment points and use a detection device to collect and detect the gas concentration in the soil.
[0040] First, a hole of about 50-70cm is drilled using drilling equipment; then, the in-situ gas sampling device is vertically spirally drilled into the hole to collect the gas; finally, the gas pipe is connected to the outlet of the gas sampling device and the inlet of the gas detector to start the detection, measuring the concentration of volatile organic compounds accumulated in the surface soil and the biochemical gases produced by biogeochemical reactions such as mineralization, methanogenesis, and methane oxidation during their diffusion to the surface.
[0041] The detection device is a surface soil gas micro-disturbance detection device; the drilling equipment includes, but is not limited to, steel drills, and the material can also be stainless steel, iron, copper, etc.; the gas detectors include, but are not limited to, real-time GC online analysis, ultraviolet spectrometers, infrared spectrometers, and other gas detection instruments; the biogeochemical reactions that occur during the diffusion of volatile organic compounds to the surface include, but are not limited to, mineralization, methanogenesis, and methane oxidation; the biochemical metabolism-related gases include, but are not limited to, CO2, O2, CH4, H2, H2S, HCHO, NH3, etc.
[0042] S300. The collected gas concentration data is fitted using a curve fitting model. The cumulative probability curve is divided into intervals. The optimal regression curve for each interval is analyzed and determined. Then, the intersection of the regression curves of two adjacent intervals in the cumulative probability curve is used as the threshold for partitioning.
[0043] Specifically, the measurement parameters, significance coefficients, and correlation coefficients were determined through curve fitting. Furthermore, based on the three-interval model theory of pollution source-source region-pollution plume, the cumulative probability curve was partitioned according to the principle of linear regression optimization.
[0044] S400. Based on the zoning thresholds and using the interpolation method, draw a planar distribution map of each pollution index.
[0045] The interpolation methods include, but are not limited to, one of the following: Kriging interpolation, inverse distance weighted interpolation, natural neighbor interpolation, and nearest neighbor interpolation. Furthermore, the indicators delineated by the pollution plume range include, but are not limited to, VOCs, CO2, O2, CH4, H2, H2S, HCHO, and NH3.
[0046] The embodiments of this invention enable the detection of relevant gas concentrations in the subsurface layers of soil through minimally invasive operations on the top 50cm of soil, and also enable the rapid delineation of the range of pollution plumes. The operation is simple and convenient, greatly reducing the time and cost of site investigation.
[0047] Example 2
[0048] To more clearly illustrate the present invention, a specific example of a contaminated area is used below for explanation.
[0049] (1) Sample point layout
[0050] This survey is a preliminary investigation of a contaminated area within a site. For the area to be investigated, a grid-based sampling method was used to lay out the sampling points according to statistical requirements. During the actual sampling process, adjustments were made to the proposed sampling points based on factors such as the site's actual hardening, greening, and land use. (See reference...) Figure 2 The distance between the monitoring points is approximately 10 meters in the east-west direction, and approximately 20 meters in the north-south direction due to site land use restrictions. The specific locations of the monitoring points are as follows: Figure 1 As shown, a total of 45 topsoil gas sampling points were set up.
[0051] (2) Data Acquisition and Detection
[0052] Using drilling equipment, a soil hole approximately 70cm deep was drilled at the designated sampling points. Then, an in-situ gas sampling device was vertically and spirally drilled into the hole, sealed, and the gas was collected. A gas delivery pipe was connected to the outlet of the soil gas sampling device and the inlet of a gas detector. Using a surface soil gas micro-disturbance detection device, the concentrations of volatile organic compounds accumulated in the top 50cm of soil and the biochemically related gases produced during their diffusion to the surface, including mineralization, methanogenesis, and methane oxidation, were measured. This survey tested and recorded the concentrations of VOCs, CO2, O2, and methane at each sampling point.
[0053] (3) Pollution zoning
[0054] The quantitative data of each gas concentration index tested were linearly fitted to the cumulative probability. The fitting results are shown in [reference needed]. Figure 3During this investigation, all indicators tested showed significant segmented clustering, clearly divided into three cluster segments, indicating a distinct zoning phenomenon in site pollution. Using the lower limit of each regression curve as the zoning threshold, the concentrations of pollutants or biometabolites were divided into three regions: "pollution source - source region - pollution plume".
[0055] (4) Delineation of the range of the pollution plume halo
[0056] VOCs undergo degradation during their volatilization into the earth's surface, producing CO2. Therefore, areas with high VOC content will also have relatively high CO2 content. In addition, the degradation process of VOCs consumes O2, so areas with high VOC content will have relatively low O2 content. Thus, areas with low O2 content are pollution sources, and areas with high O2 content are pollution plume areas. In areas where VOCs are present, biological metabolism will produce methanogens, resulting in relatively high methane content. Therefore, areas where pollution sources are located will exhibit high levels of VOCs, CO2, and methane, and low levels of O2.
[0057] Kriging interpolation was used to plot the planar distribution of each pollutant and its biological metabolites based on the threshold values of the regression curves for each zone. The high, medium, and low pollution zones identified in the pollution zoning process corresponded to the pollution source (pink area), source area (yellow area), and pollution plume (green area), respectively, to characterize the site's pollution planar distribution. The results are shown in [reference needed]. Figure 4 Several monitoring indicators generally indicate that the areas where points 18, 19, and 24 are located are pollution source areas. The source area extends outward from the above pollution sources, covering monitoring points 3, 4, 6, 7, 9, 17, 20, 23, 26, 27, 30, 31, and 32. The pollution plume is mainly distributed in the western part of the factory area, covering monitoring points 5, 8, 10, 11, 12, 13, 14, 15, 1, 2, 16, 22, 21, 22, 33, 34, 35, 36, and 37.
[0058] The results of this site pollution plume delineation were compared with the drilling results from subsequent site investigations. The drilling sample testing method involved extracting core samples from different strata, placing them in plastic bags, and using a pump-suction gas detector to measure VOCs content. The test results were then used to zonify pollution areas using a cumulative probability method. The VOCs zoning results for samples at 50cm and 150cm depths are shown in the attached diagram. Figure 5 Because gas volatilization occurs during the excavation process, the gas concentration test results differ slightly from those obtained by the micro-disturbance detection device used in this paper. However, the overall pollution trend is basically consistent with the zoning range of "pollution source-source area-pollution plume". Therefore, the method used in this invention to delineate the pollution plume halo of pollutants and their metabolites in the soil is accurate.
[0059] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims
1. A method for delineating the extent of a pollution plume using pollutants and their metabolites in soil, characterized in that, include: The sampling points should be set up according to the needs of the site to be investigated; Drill holes at the identified locations to a depth of 50-70cm, and use a detection device to collect and measure the gas concentration in the soil. The collected gas concentration data were fitted using a curve fitting model. The cumulative probability curve was divided into intervals, and the optimal regression curve for each interval was analyzed and determined. Then, the intersection of the regression curves of two adjacent intervals in the cumulative probability curve was used as the threshold for partitioning. Based on the zoning thresholds and using interpolation methods, a planar distribution map of each pollution index was drawn. The gas concentrations detected above refer to the volatile organic compounds accumulated in the topsoil and the gas concentrations generated by biological metabolism during their diffusion to the surface.
2. The method for delineating the extent of a pollution plume based on pollutants and their metabolites in soil according to claim 1, characterized in that, Based on site differences, one or more of the following methods are combined to set up the sampling points for the site to be investigated: systematic random sampling method, professional judgment sampling method, zonal sampling method, systematic sampling method, and square grid probability method.
3. The method for delineating the extent of a pollution plume based on pollutants and their metabolites in soil according to claim 2, characterized in that, The distance between the points in the site to be investigated can be selected as 300-500m or 10-20m.
4. The method for delineating the extent of a pollution plume based on pollutants and their metabolites in soil according to claim 1, characterized in that, The biogeochemical reactions that occur during the diffusion of volatile organic compounds to the Earth's surface are selected from mineralization, methanogenesis, and methane oxidation. The bio-metabolizing gases are selected from CO2, O2, CH4, H2, H2S, HCHO, and NH3.
5. The method for delineating the extent of a pollution plume based on pollutants and their metabolites in soil according to claim 1, characterized in that, Based on the three-interval model theory of pollution source-source area-pollution plume, the cumulative probability curve is divided into regions according to the principle of linear regression optimization.
6. The method for delineating the extent of a pollution plume based on pollutants and their metabolites in soil according to claim 1, characterized in that, The interpolation method is selected from one of the following: Kriging interpolation, inverse distance weighted interpolation, natural neighbor interpolation, and nearest neighbor interpolation.
7. The method for delineating the extent of a pollution plume based on pollutants and their metabolites in soil according to claim 1, characterized in that, The indicators used to delineate the range of the pollution plume are selected from VOCs, CO2, O2, CH4, H2, H2S, HCHO, and NH3.