A method for tracing organic pollution micro-disturbance based on multi-dimensional detection of shallow surface soil

Abstract

The application discloses a kind of organic pollution micro-disturbance tracing methods based on shallow surface soil multidimensional detection, comprising the following steps, in combination with the potential pollution source arrangement survey point;To survey point micro-disturbance multicomponent soil gas test and microorganism sampling, and quantitative analysis multiple indicative indicative functional gene;On this basis, the abnormal range of each index is circled;Through the joint analysis of multidimensional index, the source of pollution and pollution path are judged, and source analysis is realized.The method of the application only carries out micro-disturbance sampling analysis on shallow surface about 50cm or shallower, and the source of pollution and path in the soil and groundwater under it can be found out, which is simple to operate, can greatly shorten the tracing time and save the tracing cost.

Description

Technical Field

[0001] This invention relates to the field of pollution source tracing technology, and in particular to a method for tracing the source of organic pollution through micro-disturbance based on multidimensional detection of shallow surface soil. Background Technology

[0002] The current methods for tracing the source of soil and groundwater pollution at sites, both domestically and internationally, mainly employ investigation techniques based on drilling, well completion, sampling, testing, and analysis.

[0003] However, in practice, especially for enterprises in production, the source tracing method based on drilling surveys is often constrained by both construction conditions and costs, resulting in problems such as high resistance and low accuracy in source tracing. Developing minimally invasive, portable, and economical micro-disturbance source tracing technology is the development trend.

[0004] In organically contaminated sites, organic pollutants in soil and groundwater undergo microbial degradation. During the degradation process, oxygen (O2) is consumed, and gases such as carbon dioxide (CO2), methane (CH4), hydrogen (H2), and hydrogen sulfide (H2S) are produced and diffused to the surface. Therefore, there will be abnormal concentrations of gases such as O2, CO2, CH4, H2, and H2S in the surface soil of organically contaminated sites.

[0005] However, different polluted areas have different gas compositions. For example, in the pollution source area, O2 and NO3 are lacking. - SO4 2- Electron acceptors, organic matter primarily produces methane under the action of methanogenic microorganisms, resulting in the detection of CH4 on the Earth's surface; in near-source regions, SO4 is typically formed. 2- In the reduction zone, H2S is generated; while in the low-concentration pollution source zone, CH4 and H2S are usually not generated.

[0006] In addition, if VOCs are present in the pollutants, they usually also leach to the surface, leading to abnormal concentrations of VOCs and oxidizing bacteria on the surface, such as... Figure 1 As shown.

[0007] Therefore, based on the above principles, and considering the abnormal characteristics of these shallow surface indicators in conjunction with the distribution of pollution sources, the sources and status of pollution in the underlying soil and groundwater can be inferred. Summary of the Invention

[0008] The purpose of this invention is to address the problem that existing source tracing methods, which mainly rely on drilling surveys, are often constrained by both construction conditions and costs, and to provide a source tracing method for organic pollution based on multidimensional detection of shallow surface soil using micro-disturbance.

[0009] The technical solution adopted to achieve the purpose of this invention is: A method for tracing the source of organic pollution through micro-disturbance based on multidimensional detection of shallow surface soil includes the following steps: Step 1: Draw a map of the contaminated site to be tested. The map includes potential pollution sources. Survey points are set up based on the potential pollution sources. Step 2: Perform micro-perturbation drilling at the location of each of the survey points; Step 3: Collect soil gas at the opening of the borehole formed in Step 2; Step 4: Analyze the concentration of indicator gases in the soil gas, wherein the indicator gases are VOCs, O2, CO2, H2, H2S and CH4; Step 5: Collect soil samples as microbial samples at each of the survey points, with the soil sample depth being 40-60 cm; Step 6: Quantitative analysis of indicator functional genes in the microbial sample, including propane monooxygenase (…). PrmA ) gene, alkane monooxygenase ( AlkB ) gene and catechol dioxygenase ( C12O or C23O )Gene; Step 7, Delineate the abnormal range of indicators: Draw contour maps for each indicator, delineating background areas, high background areas, abnormal areas, and high anomaly areas. The indicators include the concentrations of indicative gases obtained in Step 4 and the content of indicative functional genes obtained in Step 6; the indicators include VOCs concentration, CO2 concentration, H2 concentration, etc. PrmA Gene content, AlkB Gene content, C12O Gene content; Step 8: Combining the meaning of the indicators and the contour maps of each indicator obtained in Step 7, first determine the pollution situation based on the concentration of the indicator gas. The pollution situation includes non-volatile organic pollution, volatile organic pollution, no pollution, near-surface pollution, or recent pollution. Then, determine the source of pollutants based on the indicator functional genes. The source of pollutants includes alkane pollution, aromatic hydrocarbon pollution, non-petroleum organic pollution, or petroleum organic pollution. Interpret the pollution situation and the source of pollutants.

[0010] In the above technical solution, in step 2, a hole is drilled using a steel chisel, electric drill, or hand drill.

[0011] In the above technical solution, in step 2, the diameter of the hole is 20~30mm and the depth is 50~70cm.

[0012] In the above technical solution, in step 3, the orifice is sealed with a plug with a polytetrafluoroethylene (PTFE) capillary tube. One end of the PTFE capillary tube is connected to the orifice, and the other end is connected to the gas detector.

[0013] In the above technical solution, in step 4, an active aspiration type multi-parameter portable gas analyzer is used to measure the soil gas concentration on site.

[0014] In the above technical solution, in step 5, a soil sample is collected using a sterilized Luoyang shovel or hand drill and placed in a sterile container for low-temperature preservation.

[0015] In the above technical solution, in step 6, soil nucleic acid is extracted, and quantitative real-time PCR is used to quantify the indicative functional genes.

[0016] In the above technical solution, the organic pollution micro-disturbance source tracing method further includes step 9, determining the pollution migration path: based on the shape of the pollution range delineated in the contour map of each indicator obtained in step 7, combined with the groundwater level data of the pollution site to be detected and the surrounding area, the long-term flow field of groundwater is inferred, thereby determining the migration direction of pollutants with groundwater.

[0017] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention only requires micro-disturbance sampling analysis on the shallow surface of about 50cm to identify the source and path of pollution in the underlying soil and groundwater. It is simple to operate, can greatly shorten the source tracing time, and save source tracing costs.

[0018] 2. This invention employs indicator gases (VOCs, O2, CO2, H2, H2S, or CH4) and indicator functional genes ( PrmA Gene, AlkB Gene, C12O or C23O The system performs multi-dimensional detection of genes. VOCs are indicators of volatile organic compounds, other indicator gas indicators are general indicators of organic compounds, and functional gene indicators are indicators for individual pollutants. The indicators corroborate and complement each other, resulting in high reliability of source tracing. Attached Figure Description

[0019] Figure 1 This is a conceptual model diagram illustrating the principle of tracing the source of micro-disturbance in organically contaminated sites.

[0020] Figure 2 This is an example of the groundwater flow field in the survey area.

[0021] Figure 3 This is a layout diagram of the survey points in the example.

[0022] Figure 4 These are the indicators for each study area in the example (a is VOCs, b is CO2, c is H2, d is...). PrmA e is AlkB f is C12OThe division of the background area (white), high background area (green), abnormal area (yellow), and high abnormal area (red). Detailed Implementation

[0023] The present invention will be further described in detail below with reference to specific embodiments.

[0024] It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0025] Taking a certain oil-contaminated site and its surrounding area as an example, a method for tracing the source of organic pollution through micro-disturbance based on multidimensional detection of shallow surface soil adopts the following steps: Step 1, Survey point layout: Based on the production process, current and historical distribution of equipment of potential polluting enterprises and plots, surface hardening conditions, site hydrogeological conditions, etc., survey points are reasonably laid out.

[0026] like Figure 2 As shown, the area contains oil depots, furniture factories, and other businesses, and has multiple historical and current potential sources of pollution, including oil storage tanks and loading / unloading platforms. The aquifer consists of Quaternary loose deposits, and the regional groundwater flow direction is from southeast to northwest. However, the groundwater at the site flows south and north due to mining activities. Based on this understanding, survey points were established, and their distribution is shown in the figure. Figure 3 As shown.

[0027] The number and density of survey points need to be determined based on the area of ​​the area to be investigated and the size of the pollution source to be captured. For details, please refer to the "Specification for Soil and Groundwater Investigation and Risk Assessment of Contaminated Sites (China Geological Survey Standard) DD201406". Generally, the spacing between survey points is less than 20m.

[0028] Step 2, micro-disturbance hole formation: Using a steel rod approximately 100 mm long and 20 mm in diameter, drill holes approximately 20 mm in diameter and 500 mm deep at each survey point.

[0029] Step 3, Connect the portable gas detector: The borehole opening is sealed with a plug with a PTFE tube, that is, one end of the PTFE tube is connected to the borehole opening and the other end is connected to the gas detector.

[0030] Step 4, shallow surface soil gas field test: Use an active aspiration type multi-parameter (including VOCs, O2, CO2, H2, H2S, CH4) portable gas analyzer to measure the gas concentration in the borehole. Record the values ​​of each indicator after the instrument readings stabilize.

[0031] Step 5, Microbial sample collection: Using a sterilized hand drill, collect soil samples at a depth of about 50cm from the survey point, place them in a sterile bag, preserve them on dry ice, and transport them to the laboratory as soon as possible for storage in a refrigerator at a temperature below -80℃.

[0032] Step 6, Quantification of indicative functional genes: Nucleic acid was extracted from the soil, and propane monooxygenase (PPI) was quantified using real-time PCR. PrmA ), alkane monooxygenase ( AlkB Catechol dioxygenase ( C12O Quantification of indicator functional genes.

[0033] Step 7, Delineate the Abnormal Range of Indicators: Draw contour maps for each indicator, and based on cumulative probability mathematical statistics, delineate areas such as background areas, high background areas, abnormal areas, and high anomaly areas, for example... Figure 4 As shown, the indicators include VOCs concentration, CO2 concentration, H2 concentration, PrmA Gene content, AlkB Gene content, C12O Gene content.

[0034] Step 8, Pollution Source Determination: Based on the different indicator signal responses of different pollutants, and based on the understanding of material analysis and pollutant transformation pathways, interpret the pollution situation and pollutant source according to the meaning of each indicator (for detailed meanings of specific indicators in some situations, see Appendix 1 and Appendix 2).

[0035] Appendix 1. Pollution Indicator Matrix for Shallow Surface Soil Gas Indicators (Partial) *: √ indicates an abnormality, i.e., a decrease in O2 concentration or an increase in other indicators; × indicates no abnormality.

[0036] Appendix 2. Pollution Indicator Matrix of Microbial Function (Partial) in Shallow Surface Soil *: √ indicates an anomaly, × indicates no anomaly.

[0037] Combined with Appendix 1 and Appendix 2 and Figure 4 In this embodiment, VOCs ( Figure 4 a) CO2 Figure 4 (b) and H2 ( Figure 4 The abnormal region in (c) Figure 4 Yellow area) and high anomaly area ( Figure 4 The red areas are widely distributed, including loading and unloading areas, the area around oil tank areas, and the idle farmland west of the furniture factory; while the indicative functional gene indicators that can indicate petroleum hydrocarbons, PrmA , AlkB , C12O The indicators showed no abnormalities in the agricultural land (idle) area west of the furniture factory.

[0038] These indicators show that volatile organic compounds (VOCs) are present in both the abnormal and highly abnormal areas, but the pollutant components are different: the pollutant components around the loading and unloading area and oil tank area on the west side contain alkanes and aromatics, consistent with the signal response of the oil tank area, suggesting that the pollutants in this area are petroleum hydrocarbons, mainly from the oil storage tanks; while the pollutants in the agricultural land (idle) area to the west of the furniture factory are also VOCs, but do not contain alkanes and aromatics (non-petroleum VOCs), consistent with the material characteristics of the raw materials of the furniture factory, suggesting that they come from the pollution of the furniture factory on the east side.

[0039] (9) Determine the pollution migration path: Based on the shape of the delineated pollution area, combined with the groundwater level data of the enterprise or site and the surrounding area, infer the long-term flow field of groundwater, and thus determine the direction of pollutant migration with groundwater.

[0040] In the embodiment, with Figure 4 Taking the CO2 index of Zhongb as an example, with the oil tank area as the pollution source, pollution areas appeared in its northwest and south. Based on this, it is inferred that the groundwater flow would flow to the northwest and south in this area.

[0041] Groundwater flow field survey shows ( Figure 2 The main direction of groundwater here is northwest, and the farmland to the south is pumped out from time to time, causing the water to flow south from time to time.

[0042] Therefore, the direction of pollution migration is related to the flow direction of groundwater in and around the site. Figure 2 The results are basically the same: On the west side, the pollution source is the oil tank area, and the pollution plume extends northwestward along the direction of groundwater flow. Due to the irregular pumping of water from the farmland on the south side, the pollution plume will extend southwestward. On the east side, the pollution source is the furniture factory, and the pollution plume extends westward along the direction of groundwater flow.

[0043] The above description is only a preferred embodiment of the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for tracing the source of organic pollution through micro-disturbance based on multidimensional detection of shallow surface soil, characterized in that, Includes the following steps: Step 1: Draw a map of the contaminated site to be tested. The map includes potential pollution sources. Survey points are set up based on the potential pollution sources. Step 2: Perform micro-perturbation drilling at the location of each of the survey points; Step 3: Collect soil gas at the opening of the borehole formed in Step 2; Step 4: Analyze the concentration of indicator gases in the soil gas, wherein the indicator gases are VOCs, O2, CO2, H2, H2S and CH4; Step 5: Collect soil samples as microbial samples at each of the survey points, with the soil sample depth being 40-60 cm; Step 6: Quantitative analysis of the indicator functional genes in the microbial sample, including propane monooxygenase gene, alkane monooxygenase gene, and catechol dioxygenase gene; Step 7, Delineate the abnormal range of indicators: Draw contour maps for each indicator, delineating background areas, high background areas, abnormal areas, and high anomaly areas. The indicators include the concentrations of indicative gases obtained in Step 4 and the contents of indicative functional genes obtained in Step 6; the indicators include VOCs concentration, CO2 concentration, H2 concentration, ... PrmA Gene content, AlkB Gene content, C12O Gene content; Step 8: Combining the meaning of the indicators and the contour maps of each indicator obtained in Step 7, first determine the pollution situation based on the concentration of the indicator gas. The pollution situation includes non-volatile organic pollution, volatile organic pollution, no pollution, near-surface pollution, or recent pollution. Then, determine the source of pollutants based on the indicator functional genes. The source of pollutants includes alkane pollution, aromatic hydrocarbon pollution, non-petroleum organic pollution, or petroleum organic pollution. Interpret the pollution situation and the source of pollutants.

2. The method for tracing the source of organic pollution using micro-disturbance as described in claim 1, characterized in that, In step 2, holes are drilled using a steel chisel, electric drill, or hand drill.

3. The method for tracing the source of organic pollution using micro-disturbance as described in claim 1, characterized in that, In step 2, the diameter of the hole is 20-30 mm and the depth is 50-70 cm.

4. The method for tracing the source of organic pollution using micro-disturbance as described in claim 1, characterized in that, In step 3, the orifice is sealed with a plug with a polytetrafluoroethylene (PTFE) capillary tube. One end of the PTFE capillary tube is connected to the orifice, and the other end is connected to the gas detector.

5. The method for tracing the source of organic pollution using micro-disturbance as described in claim 1, characterized in that, In step 4, an active aspiration type multi-parameter portable gas analyzer is used to measure the soil gas concentration on-site.

6. The method for tracing the source of organic pollution using micro-disturbance as described in claim 1, characterized in that, In step 5, soil samples are collected using a sterilized Luoyang shovel or hand drill and stored in a sterile container at low temperature.

7. The method for tracing the source of organic pollution using micro-disturbance as described in claim 1, characterized in that, In step 6, soil nucleic acids are extracted, and quantitative real-time PCR is used to quantify indicative functional genes.

8. The method for tracing the source of organic pollution using micro-disturbance as described in claim 1, characterized in that, It also includes step 9, determining the pollution migration path: based on the shape of the pollution range delineated in the contour map of each indicator obtained in step 7, combined with the groundwater level data of the pollution site to be tested and the surrounding area, the long-term flow field of groundwater is inferred, thereby determining the direction of pollutant migration with groundwater.

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