CN116593604A - Soil gas quantitative passive detection system based on balance principle and use method - Google Patents
Soil gas quantitative passive detection system based on balance principle and use method Download PDFInfo
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- 238000001514 detection method Methods 0.000 title claims abstract description 184
- 239000002680 soil gas Substances 0.000 title claims abstract description 94
- 238000000034 method Methods 0.000 title claims abstract description 38
- 238000005070 sampling Methods 0.000 claims abstract description 133
- 239000000463 material Substances 0.000 claims abstract description 46
- 239000006004 Quartz sand Substances 0.000 claims abstract description 44
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims abstract description 44
- 229910000278 bentonite Inorganic materials 0.000 claims abstract description 35
- 239000000440 bentonite Substances 0.000 claims abstract description 35
- SVPXDRXYRYOSEX-UHFFFAOYSA-N bentoquatam Chemical compound O.O=[Si]=O.O=[Al]O[Al]=O SVPXDRXYRYOSEX-UHFFFAOYSA-N 0.000 claims abstract description 35
- 238000001179 sorption measurement Methods 0.000 claims abstract description 35
- 238000007789 sealing Methods 0.000 claims abstract description 18
- 230000000903 blocking effect Effects 0.000 claims abstract description 17
- 238000005516 engineering process Methods 0.000 claims abstract description 15
- 239000007789 gas Substances 0.000 claims abstract description 8
- 239000000523 sample Substances 0.000 claims description 66
- 239000003344 environmental pollutant Substances 0.000 claims description 33
- 231100000719 pollutant Toxicity 0.000 claims description 33
- 238000005553 drilling Methods 0.000 claims description 25
- 230000008569 process Effects 0.000 claims description 22
- 238000009792 diffusion process Methods 0.000 claims description 19
- 239000007787 solid Substances 0.000 claims description 17
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 14
- 239000003463 adsorbent Substances 0.000 claims description 11
- 239000012528 membrane Substances 0.000 claims description 11
- 238000009434 installation Methods 0.000 claims description 8
- 238000000429 assembly Methods 0.000 claims description 7
- 230000000712 assembly Effects 0.000 claims description 7
- 239000011083 cement mortar Substances 0.000 claims description 6
- 238000003795 desorption Methods 0.000 claims description 6
- 238000004140 cleaning Methods 0.000 claims description 5
- 239000011521 glass Substances 0.000 claims description 5
- 230000004888 barrier function Effects 0.000 claims description 4
- 239000000356 contaminant Substances 0.000 claims description 3
- 238000005192 partition Methods 0.000 claims description 3
- 238000010521 absorption reaction Methods 0.000 claims 1
- 150000001875 compounds Chemical class 0.000 claims 1
- 238000011002 quantification Methods 0.000 claims 1
- 239000012855 volatile organic compound Substances 0.000 abstract description 21
- 239000002689 soil Substances 0.000 abstract description 20
- 238000004364 calculation method Methods 0.000 abstract description 2
- 238000010586 diagram Methods 0.000 description 5
- 238000012360 testing method Methods 0.000 description 4
- 230000000694 effects Effects 0.000 description 3
- 230000036541 health Effects 0.000 description 3
- 229920000620 organic polymer Polymers 0.000 description 3
- 238000002290 gas chromatography-mass spectrometry Methods 0.000 description 2
- 238000011835 investigation Methods 0.000 description 2
- 239000012071 phase Substances 0.000 description 2
- 238000012502 risk assessment Methods 0.000 description 2
- 239000007790 solid phase Substances 0.000 description 2
- 238000003466 welding Methods 0.000 description 2
- 238000012512 characterization method Methods 0.000 description 1
- 238000012937 correction Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 238000011010 flushing procedure Methods 0.000 description 1
- 235000003642 hunger Nutrition 0.000 description 1
- 230000009545 invasion Effects 0.000 description 1
- 239000007791 liquid phase Substances 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 238000013508 migration Methods 0.000 description 1
- 230000005012 migration Effects 0.000 description 1
- 230000035515 penetration Effects 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 230000008439 repair process Effects 0.000 description 1
- 229910001220 stainless steel Inorganic materials 0.000 description 1
- 239000010935 stainless steel Substances 0.000 description 1
- 230000037351 starvation Effects 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N30/00—Investigating or analysing materials by separation into components using adsorption, absorption or similar phenomena or using ion-exchange, e.g. chromatography or field flow fractionation
- G01N30/02—Column chromatography
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N1/00—Sampling; Preparing specimens for investigation
- G01N1/02—Devices for withdrawing samples
- G01N1/22—Devices for withdrawing samples in the gaseous state
- G01N1/2294—Sampling soil gases or the like
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N30/00—Investigating or analysing materials by separation into components using adsorption, absorption or similar phenomena or using ion-exchange, e.g. chromatography or field flow fractionation
- G01N30/02—Column chromatography
- G01N30/04—Preparation or injection of sample to be analysed
- G01N30/06—Preparation
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N30/00—Investigating or analysing materials by separation into components using adsorption, absorption or similar phenomena or using ion-exchange, e.g. chromatography or field flow fractionation
- G01N30/02—Column chromatography
- G01N30/62—Detectors specially adapted therefor
- G01N30/72—Mass spectrometers
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N30/00—Investigating or analysing materials by separation into components using adsorption, absorption or similar phenomena or using ion-exchange, e.g. chromatography or field flow fractionation
- G01N30/02—Column chromatography
- G01N2030/022—Column chromatography characterised by the kind of separation mechanism
- G01N2030/025—Gas chromatography
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
- Y02A50/00—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE in human health protection, e.g. against extreme weather
- Y02A50/20—Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters
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- Physics & Mathematics (AREA)
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- Immunology (AREA)
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Abstract
The invention discloses a soil gas quantitative passive detection system based on a balance principle and a use method thereof, wherein the passive detection system comprises a detection well and one or more passive soil gas detection components with unequal lengths, which are inserted into the detection well; the detection well comprises a well hole, a plurality of layers of clean quartz sand filter material gas guide layers are paved in the well hole, a layer of clean bentonite blocking layer is paved between each layer of clean quartz sand filter material gas guide layer at intervals, and a layer of wellhead sealing layer is arranged at the top of the well hole; the passive soil gas detection assembly comprises a detection tube and a sampler, wherein the sampler is detachably arranged at the center of the detection tube, and the passive soil gas detection assembly has the advantages of simple integral structure, convenience in use, reduction of sampling cost and improvement of sampling efficiency; the use method provides a calculation method of the concentration of VOCs and an obtaining mode of each parameter based on a balance principle, and solves the problem that accurate quantitative detection is difficult to realize due to the fact that the adsorption rate cannot be accurately obtained in the traditional soil pneumatic detection technology.
Description
Technical Field
The invention relates to the technical field of site pollution investigation and risk assessment, in particular to a soil gas quantitative passive detection system based on a balance principle and a use method thereof.
Background
Volatile organic compounds (Volatile Organic Compounds, VOCs) commonly exist in polluted sites, the detection rate can reach 60% -80%, and the VOCs can enter the room through diffusion or convection through channels such as building floor cracks and the like so as to cause harm to human health, namely, the steam invasion exposure risk. Because of the characteristics of volatile VOCs, site heterogeneity and the like, great uncertainty exists in the characterization of VOCs pollution and risk assessment in the site. For example, the peculiar smell is obvious in the on-site drilling sampling process of many sites, the reading of the portable photo-ion detector is up to 1000 ppm, but various VOCs in soil samples sent to a laboratory are not detected or the detection concentration is low, and in the situation, management decision is carried out only according to the detection result of the soil samples, so that the health risk of the VOCs is easily underestimated, and the safe utilization of the sites cannot be ensured. In addition, only when detecting soil, a linear balance distribution model is usually adopted to predict the concentration of pollutants in soil gas at a corresponding position based on the concentration of pollutants in soil, and then the migration and exposure model is used to predict the health risk of people. However, practical application finds that the evaluation result of the method is too conservative, which easily results in excessive site repair and causes fund waste.
The concentration of VOCs in the soil gas can be detected to solve the problem better. At present, the detection of the soil gas is mainly divided into active detection and passive detection, wherein the active soil gas detection technology is relatively mature, but is generally only suitable for fields with low viscosity and low water content, the sampling process is complex, the accurate sampling flow rate and sampling volume are required to be controlled based on the concentration of pollutants in the soil gas, the stratum structure, the type of adsorbent in a selected sampling tube and other factors, and the variability of the sampling result is large. The existing passive soil gas detection technology is mainly based on a linear dynamic adsorption principle, the principle considers that the pollutant mass adsorbed by a passive sampler at the initial stage of field installation is in linear relation with the installation time of the sampler, and the passive sampler is usually installed at the field for 7 days or 14 days and then is retrieved to the laboratory to analyze the pollutant mass adsorbed in the sampler, and the pollutant concentration in the soil gas at a sampling point is further calculated according to the adsorption rate of the sampler. Because the soil is a multiphase multicomponent system, the distribution of pollutants between soil gas-liquid-solid phases is in a dynamic balance state, the key of the soil gas passive detection technology is to select a passive sampler with low adsorption rate, so that the adsorption rate is not higher than the rate of transferring and transferring the pollutants from the soil solid phase or liquid phase to the soil gas into the passive sampler, so as not to cause starvation effect, and further to cause the distortion of the final detection result. The factors such as the pollutant concentration, the pollutant components, the soil humidity, the temperature and the like in the actual field have large space variability, and even if the soil gas in the specific field is used for carrying out the adsorption rate correction of the passive sampler, the accuracy of the quantitative detection of the concentration of the passive sampler is also very ensured. Therefore, the current soil gas passive sampling technology based on the linear dynamic adsorption principle is generally used for describing the field pollution degree semi-quantitatively, and the areas with heavy potential pollution are screened out by installing the pollutant mass adsorbed in the samplers at the same time so as to guide the arrangement of other investigation points such as active soil gas and the like.
Disclosure of Invention
The invention aims to provide a soil gas quantitative passive detection system based on a balance principle and a use method thereof, wherein the system combines the multi-phase multi-interface dynamic distribution characteristics of VOCs in a field to finish the soil gas quantitative passive detection in 72h, thereby solving the problems of safety and economy and long time in the prior art; the use method provides a calculation method of the concentration of VOCs and an obtaining mode of each parameter based on a balance principle, and solves the problem that accurate quantitative detection is difficult to realize due to the fact that the adsorption rate cannot be accurately obtained in the traditional soil pneumatic detection technology.
In order to achieve the above purpose, the present invention adopts the following technical scheme:
a soil gas quantitative passive detection system based on a balance principle comprises a detection well and one or more passive soil gas detection components with unequal lengths, wherein the passive soil gas detection components are inserted into the detection well, a single-hole single-tube detection process is formed when one passive soil gas detection component is inserted into the detection well, and a single-hole multi-tube detection process is formed when a plurality of passive soil gas detection components with unequal lengths are inserted into the detection well;
the detection well comprises a well hole, when the single-hole single-tube detection technology is adopted for quantitative detection of soil gas, a layer of clean quartz sand filter material air guide layer is paved at the bottom of the passive soil gas detection component in the well hole, a clean bentonite blocking layer is arranged at the top of the clean quartz sand filter material air guide layer to the wellhead of the well hole, and a wellhead sealing layer is also arranged at the top of the clean bentonite blocking layer; when the single-hole multi-tube detection technology is adopted for quantitative detection of soil gas, a layer of clean quartz sand filter material gas guiding layer is paved at the bottom positions of a plurality of passive soil gas detection assemblies with unequal lengths in the well hole, a clean bentonite blocking layer is arranged at other positions in the well hole to the wellhead of the well hole, and a wellhead sealing layer is arranged at the wellhead of the well hole to the ground;
the passive soil gas detection assembly comprises a detection tube and a sampler, and the sampler is detachably arranged at the center of the detection tube;
the detection tube comprises a solid tube, a tube connector, an air inlet screen tube and a tube sealer, wherein the top end of the air inlet screen tube is open, the tube body is uniformly and alternately provided with a container with air inlet holes, the top end of the air inlet screen tube is fixedly communicated with the bottom end of the solid tube through the tube connector, the solid tube is of a tubular structure, and the top end of the solid tube is sealed through the tube sealer;
the sampler comprises a T-shaped handle, a push rod, a first connecting piece, a passive sampling probe and a pipeline-to-middle device, wherein the push rod is fixedly arranged at the center of the detection pipe through at least two pipeline-to-middle devices, the bottom of the push rod penetrates out of the pipeline connector, the bottom end of the push rod is connected with the passive sampling probe through the first connecting piece, the top end of the push rod is detachably connected with the T-shaped handle, the push rod is driven to rotate by screwing the T-shaped handle so as to assist the first connecting piece to be in airtight connection with the pipeline connector, and therefore the passive sampling probe is fixedly arranged in the air inlet screen pipe to measure the soil gas; and after the sampler is installed in place, the T-shaped handle is disassembled, and the pipeline sealer is fixedly installed at the top end of the real pipe.
Preferably, the main structure of the pipe connector is a disc-shaped structure with a threaded through hole with a sinking groove at the central position, rings are integrally arranged on the upper surface and the lower surface of the main structure, a threaded connection area is arranged on the outer side of the rings, and the top of the air inlet screen pipe and the bottom of the real pipe are connected with the pipe connector through the threaded connection area.
Preferably, the pipeline sealer is a disc cover-shaped structure, and threads are arranged on the side wall below the pipeline sealer.
Preferably, the passive sampling probe comprises a sampling probe, a porous supporting plate, a passive sampling membrane and a second connecting piece, wherein the sampling probe is of a porous net-shaped frame structure, the top of the sampling probe is fixedly connected with the bottom of the first connecting piece through the second connecting piece, the porous supporting plate is obliquely arranged at the bottom of the sampling probe, and the passive sampling membrane is arranged on the porous supporting plate.
Preferably, the second connecting piece is of a cylindrical structure, an internal thread connecting area is arranged at the top end of the second connecting piece, and the sampling probe is fixedly clamped at the bottom end of the second connecting piece.
Preferably, the first connecting piece is a cover-shaped structure, a rubber sealing ring is arranged at the bottom side of the cover-shaped structure, the top of the cover-shaped structure is attached to the sinking groove of the pipeline connector, the bottom of the first connecting piece is sequentially provided with a first threaded area and a second threaded area from top to bottom, the first threaded area is fixedly connected with the threaded connection area of the pipeline connector, and the second threaded connection area is fixedly connected with the internal threaded connection area of the second connecting piece.
Preferably, the passive sampling film is required to satisfy a balanced distribution coefficient of not more than 700 cm 3 And/g, effective diffusion coefficient is not less than 10 -7 cm 2 And/s, the material of the passive sampling film is organic polymer.
Preferably, the passive sampling film needs to meet the requirements of 50-100 mm in length, 3-5 mm in width and not more than 1.5mm in thickness.
The application method of the soil gas quantitative passive detection system based on the balance principle comprises the following steps:
drilling a well hole, namely drilling the well hole at a designed detection point position to form the well hole;
arranging a detection pipe, when a single-hole single-pipe detection process is selected, firstly drilling a well hole, stopping drilling after the well hole depth reaches a designed depth, and lifting a drilling tool after removing chips and dregs in the well hole; filling clean quartz sand filter materials with the thickness of 5cm into the well hole, vertically filling a detection pipe, and then continuously filling the clean quartz sand filter materials to the designed height on the periphery of the detection pipe filled in the well hole to form a clean quartz sand filter material air guide layer; adding clean water after filling clean dry bentonite with the thickness of 30cm at the top of the clean quartz sand filter material gas-guide layer, so that the clean dry bentonite absorbs water and swells until the clean bentonite layer reaches the wellhead of the well hole to form a clean bentonite barrier layer, and finally filling cement mortar into the well hole to the ground to form a wellhead sealing layer; when the single-hole multi-pipe detection process is selected, firstly, drilling a well hole, stopping drilling after the well hole depth reaches the designed depth, and then lifting a drilling tool after removing debris and dregs in the well hole; filling clean quartz sand filter materials with the thickness of 5cm into the well hole, vertically burying the longest detection tube, and then continuously filling the clean quartz sand filter materials to the designed height around the longest detection tube buried in the well hole to form a clean quartz sand filter material air guide layer; adding clean water after filling 30cm clean dry bentonite on the top of the clean quartz sand filter material gas-guide layer, enabling the clean dry bentonite to absorb water and expand until the depth of a second long detection pipe is located, forming a clean bentonite blocking layer, then filling Fang Zhuangtian cm thick clean quartz sand filter material on the second long detection pipe vertically, repeating the subsequent steps of the longest detection pipe until all detection pipes are filled, paving the clean quartz sand filter material gas-guide layer and the clean bentonite blocking layer to the wellhead of a well hole in sequence, and finally filling cement mortar into the well hole to the ground to form a wellhead sealing layer;
step three, connecting a sampler, fixedly connecting the bottom end of a push rod with a first connecting piece, fixedly connecting the top end of the push rod with a T-shaped handle, fixing a pipeline to a middle device at a corresponding position in the push rod, then placing a passive sampling membrane on a porous supporting plate obliquely arranged at the bottom of a sampling probe, and rapidly fixedly connecting the passive sampling probe with a second threaded region of the first connecting piece;
step four, assembling a passive soil gas detection assembly, installing a connected sampler at the central position of a detection pipe, ensuring that a passive sampling probe passes through a threaded through hole arranged at the central position of a main body structure of a pipeline connector to enter an air inlet screen pipe under the assistance of a pushing rod, then rotating a T-shaped handle to fixedly connect a first threaded region in a first connecting piece with a threaded connection region of the pipeline connector, and attaching the top of the first connecting piece to a sinking groove of the pipeline connector; then reversely rotating the T-shaped handle to take off the T-shaped handle from the pushing rod, screwing the pipeline sealer into the top end of the solid pipe to seal the solid pipe;
step five, sampling, namely unscrewing a pipeline sealer after balancing 72 and h, mounting a T-shaped handle on a pushing rod, quickly lifting the pushing rod to lift a passive sampling probe to the ground after loosening a first connecting piece and the pipeline connector by rotating the T-shaped handle, quickly transferring the passive sampling film into a sealed glass bottle with an adsorption tube inside by using a cleaning tool after taking the passive sampling film out of the passive sampling probe, and keeping a low-temperature environment to be sent to a laboratory.
Step six, calculating the concentration of target pollutants in the soil gas, installing an adsorption tube into a thermal desorption device, detecting the mass of the target pollutants adsorbed in the adsorption tube, and calculating the concentration of the target pollutants in the soil gas at the installation position of the passive sampling probe by adopting the following formula:
wherein C is sg For corresponding to the concentration of target pollutant in soil gas at the installation position of the passive sampling probe, mg/m 3 The method comprises the steps of carrying out a first treatment on the surface of the Mc is the mass of the target pollutant adsorbed in the adsorption tube, mg; m is M p G, the mass of the passive sampling film; k (K) pg Equilibrium distribution coefficient, cm, of target pollutants in soil gas in passive sampling film 3 /g。
Preferably, the adsorption tubes in the fifth and sixth steps are filled with adsorbent, and the equilibrium adsorption distribution constant of the adsorbent is not less than 10 4 cm 3 /g, effective diffusion coefficient of not more than 10 -8 cm 2 /s。
In the invention, one or more passive soil gas detection assemblies with unequal lengths are inserted into the detection well, so that a single-hole multi-tube detection process or a single-hole multi-tube detection process is adopted to adapt to the multi-phase multi-interface dynamic distribution characteristics of VOCs in a field, and the detection accuracy is improved; the soil gas sample around the soil gas probe is not required to be pumped to the sampling tube filled with the adsorbent by using the sampling pump, so that a power supply is not required to be provided for the sampling pump, the accurate sampling flow rate and sampling volume are not required to be controlled, and the problem that water vapor and pollutants compete for the adsorption point of the adsorbent in the sampling tube to cause the penetration of the sampling tube due to the too high humidity in the soil gas is avoided, and the problem of lower detection concentration is avoided; the well flushing is not required to be carried out before the soil gas sampling to ensure that the collected soil gas sample can represent the soil gas in the natural stratum, so that the required sampling personnel are low in intensity, the sampling efficiency is high, and the sampling cost is low;
the sampler is detachably arranged at the central position of the detection tube through the T-shaped handle, the bottom of the detection tube is provided with an air inlet screen pipe, and a passive sampling probe of the sampler is placed in the air inlet screen pipe, so that VOCs in the detection well can be measured, the whole structure is simple, the use is convenient, the sampling cost is reduced, and the sampling efficiency is improved;
the passive sampling probe is provided with a passive sampling film in a porous net frame structure, and the equilibrium distribution coefficient of the passive sampling film is not more than 400 cm 3 The effective diffusion coefficient is usually not less than 10 per gram -7 cm 2 The quantitative passive detection of the soil gas can be realized in 72h, so that the balance time is effectively shortened, and the measurement efficiency is improved;
the concentration of VOCs is detected and calculated based on a balance principle, the concentration of VOCs in the soil gas is calculated without using a parameter which is obviously influenced by environmental factors, namely the adsorption rate, and the problem that the concentration of target pollutants in the soil gas at a detection point cannot be accurately and quantitatively measured by the traditional semi-quantitative soil gas passive detection technology based on the dynamic linear adsorption theory is solved;
under the objective condition that the passive sampling film cannot be infinitely thin, in order to realize rapid quantitative detection of soil gas, the VOCs have higher adsorption capacity, namely the distribution coefficient of the VOCs in the passive sample film needs to be higher than a certain value, and the effective diffusion coefficient in the passive sampling film needs to be large enough and is not lower than 10 -7 cm 2 However, the requirement for the passive sampling membrane to realize rapid equilibrium detection leads to that VOCs adsorbed on the passive sampling membrane are easy to desorb and escape in the process of transporting the sampling membrane to a test for pollutant detection, and the final detection result is low; the distribution coefficient of the pollutants is not lower than 2 orders of magnitude higher than that of the passive sampling film by the adsorbent filled in the adsorption tube, but the effective diffusion coefficient is not lower than 1 order of magnitude higher than that of the passive sampling film, the pollutants adsorbed on the passive sampling film can be transferred and fixed in the adsorption tube in the process of transporting the sample to a laboratory, the size of the adsorption tube is matched with standard thermal desorption equipment, and the sample can be immediately subjected to pollutant detection by adopting a thermal desorption-gas chromatography/mass spectrometry technology after the sample is transported to the laboratory, so that the problem of desorption and escape of the pollutants in the process of transporting the passive sampling film is effectively solved.
Drawings
FIG. 1 is a schematic diagram of a single-hole single-tube detection process structure of the invention;
FIG. 2 is a schematic diagram of a single-hole multi-tube detection process structure according to the invention;
FIG. 3 is a schematic diagram of a passive soil gas detection device according to the present invention;
FIG. 4 is an exploded view of the passive soil gas detecting assembly of the present invention;
FIG. 5 is a schematic view of a pipe connector according to the present invention;
FIG. 6 is a schematic diagram of a sampler according to the present invention;
FIG. 7 is a schematic diagram of a passive sampling probe according to the present invention;
FIG. 8 is a schematic view of a portion of the structure of the present invention;
in the figure: 1. detecting a well; 2. a passive soil gas detection assembly; 10. cleaning a quartz sand filter material gas-guide layer; 11. cleaning a bentonite barrier layer; 12. a wellhead sealing layer; 20. a detection tube; 21. a sampler; 31. a glass bottle; 32. an adsorption tube; 200. a solid pipe; 201. a pipe connector; 202. an air inlet screen pipe; 203. a pipe sealer; 210. a T-shaped handle; 211. a push rod; 212. a first connector; 213. a passive sampling probe; 214. pipeline to the middle device; 2130. a sampling probe; 2131. a porous support plate; 2132. a passive sampling membrane; 2133. and a second connecting piece.
Detailed Description
The invention is further described below with reference to the accompanying drawings:
the soil gas quantitative passive detection system based on the balance principle as shown in fig. 1 and 2 comprises a detection well 1 and one or more passive soil gas detection assemblies 2 with unequal lengths, wherein the passive soil gas detection assemblies 2 are inserted into the detection well 1, a single-hole single-tube detection process is formed when one passive soil gas detection assembly 2 is inserted into the detection well 1, and a single-hole multi-tube detection process is formed when a plurality of passive soil gas detection assemblies 2 with unequal lengths are inserted into the detection well 1.
The detection well 1 comprises a well hole, when the single-hole single-tube detection technology is adopted for quantitative detection of soil gas, a layer of clean quartz sand filter material gas guide layer 10 is paved at the bottom position of the passive soil gas detection component 2 in the well hole, a clean bentonite blocking layer 11 is arranged at the top of the clean quartz sand filter material gas guide layer 10 to the wellhead of the well hole, and a wellhead sealing layer 12 is also arranged at the top of the clean bentonite blocking layer 11; when the single-hole multi-tube detection technology is adopted for quantitative detection of soil gas, a layer of clean quartz sand filter material gas guide layer 10 is paved at the bottom positions of a plurality of passive soil gas detection assemblies 2 with different lengths in the well hole, a clean bentonite blocking layer 11 is arranged at other positions in the well hole to the wellhead of the well hole, and a wellhead sealing layer 12 is arranged at the wellhead of the well hole to the ground.
A plurality of layers of clean quartz sand filter material air guide layers 10 are paved in the well holes, a layer of clean bentonite blocking layer 11 is paved between the layers of clean quartz sand filter material air guide layers 10 at intervals, and a layer of wellhead sealing layer 12 is arranged at the top of the well holes.
The passive soil gas detecting assembly 2 shown in fig. 3 and 4 includes a detecting tube 20 and a sampler 21, the sampler 21 being detachably mounted at a central position of the detecting tube 20. The detection tube 20 comprises a solid tube 200, a pipeline connector 201, an air inlet screen 202 and a pipeline sealer 203, wherein the air inlet screen 202 is a container with an open top end and air inlets uniformly distributed on a tube body at intervals, in one embodiment, the bottom end of the air inlet screen 202 is connected with the side wall of the air inlet screen through threads, the top end of the air inlet screen 202 is fixedly communicated with the bottom end of the solid tube 200 through the pipeline connector 201, the solid tube 200 is of a tubular structure, the top end of the solid tube is sealed through the pipeline sealer 203, and the pipeline sealer 203 is of a disc cover-shaped structure. In this example, as shown in fig. 5, the main structure of the pipe connector 201 is a disc-shaped structure with a threaded through hole with a sinking groove at the central position, rings are integrally provided on the upper and lower surfaces of the main structure, a threaded connection region is provided on the outer side of the ring, and the top of the air inlet screen 202 and the bottom of the solid pipe 200 are in threaded connection with the pipe connector 201 through the threaded connection region. Threads are arranged on the side wall below the pipeline sealer 203, and the top end of the solid pipe 200 is in threaded connection with the pipeline sealer 203.
As shown in fig. 6, the sampler 21 includes a T-shaped handle 210, a push rod 211, a first connecting piece 212, a passive sampling probe 213 and a pipe-to-middle device 214, wherein the push rod 211 is fixedly installed at the central position of the detection pipe 20 through at least two pipe-to-middle devices 214, the bottom of the push rod 211 penetrates through the pipe connector 201, the bottom of the push rod 211 is connected with the passive sampling probe 213 through the first connecting piece 212, the bottom of the push rod 211 is fixedly connected with the top of the first connecting piece 212 in a welding manner, the top of the push rod 211 is detachably connected with the T-shaped handle 210 in a threaded connection manner, and the push rod 211 is driven to rotate by screwing the T-shaped handle 210 so as to assist the first connecting piece 212 to be in airtight connection with the pipe connector 201, so that the passive sampling probe 213 is fixedly placed in the air inlet screen 202 to measure the soil gas; after the sampler 21 is in place, the T-shaped handle 210 is detached, and the pipeline sealer 203 is fixedly installed at the top end of the real pipe 200.
As shown in fig. 7, the passive sampling probe 213 includes a sampling probe 2130, a porous support plate 2131, a passive sampling membrane 2132 and a second connector 2133, the sampling probe 2130 is a porous mesh frame structure having a pore size of not more than 100 mesh. The top of the sampling probe 2130 is fixedly connected with the bottom of the first connecting piece 212 through a second connecting piece 2133, a porous supporting plate 2131 is obliquely arranged at the bottom of the sampling probe 2130, a passive sampling film 2132 is arranged on the porous supporting plate 2131, the passive sampling film 2132 is made of organic polymers, and when the detection is carried out in any soil texture, the passive sampling film 2132 needs to meet the requirements of 50-100 mm in length range, 3-5 mm in width range and not more than 1.5mm in thickness. The passive sampling film 2132 also needs to meet a balanced partition coefficient typically no greater than 700 cm 3 The effective diffusion coefficient is usually not less than 10 per gram -7 cm 2 And/s. It was found through experiments that the limitation of the length and width ranges of the passive sampling film 2132 is determined according to the requirements of the thermal desorption device on the size thereof, and the thickness, the equilibrium distribution coefficient and the effective diffusion coefficient of the passive sampling film are influencing factors that influence whether the passive sampling probe 213 can complete the detection within 72 hours, and the three factors need to be satisfied: in any case of soil, the thickness is not greater than 1.5. 1.5mm, the equilibrium distribution coefficient is generally not greater than 700 cm 3 The effective diffusion coefficient is usually not less than 10 -7 cm 2 At/s, the aim of finishing detection in 72 hours can be fulfilled. But there are other special cases when the passive sampling film 2132 equilibrium distribution coefficient is typically greater than 700 cm 3 And/g, the purpose of completing detection in 72 hours can be achieved as long as the detection is not used in sandy soil.
Table 1 shows that the equilibrium distribution coefficient and the effective diffusion coefficient satisfy the conditions, and the influence of the thickness on the equilibrium time of the sampling film is verified.
From the test data in Table 1, it is found that when the equilibrium distribution coefficient, kpea, and the effective diffusion coefficient, dpe, satisfy the conditions, the film equilibrium time is within 72 hours at a thickness of 1.5mm, and the film equilibrium time is not within 72 hours at a thickness of 2 mm. This shows that when the invention detects in any soil condition, the thickness of the passive sampling film 2132 should not be more than 1.5mm when the equilibrium distribution coefficient, kpea, and the effective diffusion coefficient, dpe, meet the conditions, so that the purpose of completing the detection in 72 hours can be achieved.
Table 2, effective diffusion coefficient and thickness meet the conditions, verifying the effect of the equilibrium distribution coefficient on the equilibrium time of the sampled film.
As can be seen from the test data in Table 2, when the effective diffusion coefficient, i.e., DPE, and the thickness satisfy the conditions, the equilibrium distribution coefficient, i.e., kpea, is not more than 700 cm 3 Under the condition of/g, the aim of completing detection in 72 hours can be fulfilled by detecting in any soil property; the equilibrium distribution coefficient, kpea, exceeds 700 cm 3 In the case of/g, the purpose of completing the detection for 72 hours cannot be achieved in sandy soil. This indicates that the equilibrium distribution coefficient, kpea, of the passive sampling film 2132 is not more than 700 cm when the invention is used for detection under any soil conditions 3 And/g, the purpose of finishing detection in 72 hours can be realized.
Table 3, thickness and equilibrium distribution coefficient satisfy the conditions, verifying the effect of effective diffusion coefficient on sampling film equilibrium time.
As can be seen from the test data in Table 3, when the thickness and equilibrium distribution coefficient, kpea, satisfy the conditions, the effective diffusion coefficient, dpe, is not less than 10 -7 cm 2 In the case of/s, in any soil textureThe purpose of finishing detection in 72 hours can be realized.
The second connecting member 2133 is of a cylindrical structure, and is provided with an internally threaded connection area at the top end thereof, and the sampling probe 2130 is fixed to the bottom end of the second connecting member 2133 by welding. In this example, the sampling probe 2130, the porous backing plate 2131 and the second connector 2133 are all made of stainless steel, and the passive sampling probe 213 has an overall height of about 15cm.
The first connecting piece 212 is a cover-shaped structure, a rubber sealing ring is arranged at the bottom side of the cover-shaped structure, the top of the cover-shaped structure is attached to the sinking groove of the pipeline connector 201, the bottom of the first connecting piece 212 is sequentially provided with a first threaded area and a second threaded area from top to bottom, the first threaded area is fixedly connected with a threaded connection area of the pipeline connector 201, and the second threaded connection area is fixedly connected with an internal threaded connection area of the second connecting piece 2133.
The application method of the soil gas quantitative passive detection system based on the balance principle is characterized by comprising the following steps of:
step one, drilling a well hole, namely drilling a designed detection point position according to requirements in technical specifications such as the technical guidelines for sampling volatile organic compounds in soil and underground water of land, HJ1019-2019 and the like to form the well hole;
step two, arranging a detection pipe 20, when a single-hole single-pipe detection process is selected, firstly drilling a well hole, stopping drilling after the well hole depth reaches a designed depth, and lifting a drilling tool after removing chips and residues in the well hole; filling clean quartz sand filter materials with the thickness of 5cm into the well hole, vertically filling a detection tube 20, and then continuously filling the clean quartz sand filter materials to the designed height on the periphery of the detection tube 20 filled in the well hole to form a clean quartz sand filter material air guide layer 10; adding clean water after filling clean dry bentonite with the thickness of 30cm at the top of the clean quartz sand filter material air guide layer 10, enabling the clean dry bentonite to absorb water and expand until the clean bentonite layer reaches the wellhead of a well hole to form a clean bentonite barrier layer 11, and finally filling cement mortar into the well hole to the ground to form a wellhead sealing layer 12; when the single-hole multi-pipe detection process is selected, firstly, drilling a well hole, stopping drilling after the well hole depth reaches the designed depth, and then lifting a drilling tool after removing debris and dregs in the well hole; filling clean quartz sand filter materials with the thickness of 5cm into the well hole, vertically burying the longest detection tube 20, and then continuously filling the clean quartz sand filter materials to the designed height around the longest detection tube 20 buried in the well hole to form a clean quartz sand filter material air guide layer 10; adding clean water after filling 30cm clean dry bentonite on the top of the clean quartz sand filter material air guide layer 10, enabling the clean dry bentonite to absorb water and expand until the depth of the second long detection tube 20 is located, forming a clean quartz sand filter material with the thickness of Fang Zhuangtian cm on the clean bentonite blocking layer 11, vertically burying the second long detection tube 20, repeating the subsequent steps of the longest detection tube 20 until all detection tubes 20 are buried, paving the clean quartz sand filter material air guide layer 10 and the clean bentonite blocking layer 11 in sequence to the wellhead of a well hole, filling cement mortar into the well hole to the ground to form a wellhead sealing layer 12, and when a single-hole multi-tube detection process is adopted, enabling the vertical distance between passive sampling probes 213 in different detection tubes 20 to be not less than 1.5 m;
step three, connecting the sampler 21, fixedly connecting the bottom end of the push rod 211 with the first connecting piece 212, fixedly connecting the top end of the push rod 211 with the T-shaped handle 210, fixing the pipeline to the middle device 214 at the corresponding position in the push rod 211, in this example, arranging two pipelines to the middle device 214, wherein the distance between the pipeline at the bottom end to the middle device 214 and the first connecting piece 212 is not more than 20 cm, the distance between the pipeline at the top end to the middle device 214 and the top end of the push rod 211 is not less than 30cm, the connection between the pipeline to the middle device 214 and the push rod 211 can be fixed by adopting a bolt or a fastening ring and the like, then placing the clean passive sampling film 2132 on a porous supporting plate 2131 obliquely arranged at the bottom of the sampling probe 2130, and then rapidly fixedly connecting the passive sampling probe 213 with a second threaded region of the first connecting piece 212;
step four, assembling the passive soil gas detection assembly 2, installing the connected sampler 21 at the central position of the detection tube 20, ensuring that the passive sampling probe 213 passes through a threaded through hole arranged at the central position of the main body structure of the pipeline connector 201 and enters the air inlet screen 202 under the assistance of the push rod 211, then rotating the T-shaped handle 210 to fixedly connect a first threaded area in the first connecting piece 212 with a threaded connection area of the pipeline connector 201, and attaching the top of the first connecting piece 212 to the sinking groove of the pipeline connector 201; the T-shaped handle 210 is reversely rotated to be taken off from the pushing rod 211, and the pipeline sealer 203 is screwed into the top end of the real pipe 200 to seal the real pipe;
step five, sampling, namely unscrewing the pipeline sealer 203 after balancing 72 and h, mounting the T-shaped handle 210 on the pushing rod 211, quickly lifting the pushing rod 211 to lift the passive sampling probe 213 to the ground after loosening the first connector 212 and the pipeline connector 201 by rotating the T-shaped handle 210, quickly transferring the passive sampling film 2132 into the sealed glass bottle 31 with the adsorption tube 32 inside by using a cleaning tool after taking the passive sampling film 2132 out of the passive sampling probe 213, filling the adsorption tube 32 with the adsorbent, and keeping a low-temperature environment to a laboratory, wherein the inner diameter of the glass bottle 31 is 10mm and the height is 100 mm; the diameter of the adsorption tube 32 is 4.8 mm, and the length is 60 mm; the adsorbent is a high molecular organic polymer, and the equilibrium adsorption distribution constant of common volatile organic compounds in the adsorbent is not less than 10 4 cm 3 /g, effective diffusion coefficient of not more than 10 -8 cm 2 /s；
Step six, calculating the concentration of target pollutants in the soil gas, installing the adsorption tube 32 into a thermal desorption device, detecting the mass of the target pollutants adsorbed in the adsorption tube 32 by adopting a thermal desorption-gas chromatography/mass spectrometry technology, and calculating the concentration of the target pollutants in the soil gas at the installation position of the corresponding passive sampling probe by adopting the following formula:
wherein C is sg For corresponding to the concentration of target pollutant in soil gas at the installation position of the passive sampling probe, mg/m 3 ；M c Mg, mass of target contaminant adsorbed in the adsorption tube; m is M p G is the mass of the passive sampling film 2132; k (K) pg Passive recovery of target pollutants in soil gasEquilibrium partition coefficient in sample film 2132, cm 3 /g, which can be determined experimentally or can be queried from the product specifications.
The above embodiments are only a few descriptions of the inventive concept and implementation, and are not limited thereto, and the technical solutions without substantial transformation remain within the scope of protection under the inventive concept.
Claims (10)
1. A soil gas ration passive detection system based on balance principle, its characterized in that: the method comprises a detection well (1) and one or more passive soil gas detection components (2) with unequal lengths, wherein the passive soil gas detection components (2) are inserted into the detection well (1), a single-hole single-tube detection process is formed when one passive soil gas detection component (2) is inserted into the detection well (1), and a single-hole multi-tube detection process is formed when a plurality of passive soil gas detection components (2) with unequal lengths are inserted into the detection well (1);
the detection well (1) comprises a well hole, when the single-hole single-tube detection technology is adopted for quantitative detection of soil gas, a layer of clean quartz sand filter material air guide layer (10) is paved at the bottom position of the passive soil gas detection component (2) in the well hole, a clean bentonite blocking layer (11) is arranged at the top of the clean quartz sand filter material air guide layer (10) to the wellhead of the well hole, and a wellhead sealing layer (12) is further arranged at the top of the clean bentonite blocking layer (11); when the single-hole multi-tube detection technology is adopted for quantitative detection of soil gas, a layer of clean quartz sand filter material gas guide layer (10) is paved at the bottom positions of a plurality of passive soil gas detection assemblies (2) with unequal lengths in the well hole, a clean bentonite blocking layer (11) is arranged at other positions in the well hole to the well mouth of the well hole, and a well mouth sealing layer (12) is arranged at the well mouth of the well hole to the ground;
the passive soil gas detection assembly (2) comprises a detection tube (20) and a sampler (21), wherein the sampler (21) is detachably arranged at the center of the detection tube (20);
the detection tube (20) comprises a solid tube (200), a pipeline connector (201), an air inlet screen tube (202) and a pipeline sealer (203), wherein the air inlet screen tube (202) is a container with an open top end and air inlets uniformly distributed at intervals on a tube body, the top end of the container is fixedly communicated with the bottom end of the solid tube (200) through the pipeline connector (201), the solid tube (200) is of a tubular structure, and the top end of the solid tube is sealed through the pipeline sealer (203);
the sampler (21) comprises a T-shaped handle (210), a push rod (211), a first connecting piece (212), a passive sampling probe (213) and a pipeline-to-middle device (214), wherein the push rod (211) is fixedly arranged at the central position of the detection pipe (20) through at least two pipeline-to-middle devices (214), the bottom of the push rod penetrates out of the pipeline connector (201), the bottom of the push rod (211) is connected with the passive sampling probe (213) through the first connecting piece (212), the top of the push rod is detachably connected with the T-shaped handle (210), the T-shaped handle (210) is screwed to drive the push rod (211) to rotate so as to assist the first connecting piece (212) to be in airtight connection with the pipeline connector (201), and therefore the passive sampling probe (213) is fixedly arranged in the air inlet pipe (202) to measure soil gas; and after the sampler (21) is installed in place, the T-shaped handle (210) is detached, and the pipeline sealer (203) is fixedly installed at the top end of the real pipe (200).
2. The soil gas quantitative passive detection system based on the balance principle of claim 1, wherein: the main structure of the pipeline connector (201) is a disc-shaped structure with a threaded through hole with a sinking groove at the central position, circular rings are integrally arranged on the upper surface and the lower surface of the main structure, a threaded connection area is arranged on the outer side of each circular ring, and the top of the air inlet screen pipe (202) and the bottom of the real pipe (200) are connected with the pipeline connector (201) through the threaded connection area.
3. The soil gas quantitative passive detection system based on the balance principle of claim 1, wherein: the pipeline sealer (203) is of a disc cover-shaped structure, and threads are arranged on the side wall below the pipeline sealer.
4. The soil gas quantitative passive detection system based on the balance principle of claim 1, wherein: the passive sampling probe (213) comprises a sampling probe (2130), a porous supporting plate (2131), a passive sampling membrane (2132) and a second connecting piece (2133), wherein the sampling probe (2130) is of a porous net-shaped frame structure, the top of the sampling probe is fixedly connected with the bottom of the first connecting piece (212) through the second connecting piece (2133), the porous supporting plate (2131) is obliquely arranged at the bottom of the sampling probe (2130), and the passive sampling membrane (2132) is arranged on the porous supporting plate (2131).
5. The soil gas quantitative passive detection system based on the balance principle according to claim 4, wherein: the second connecting piece (2133) is of a cylindrical structure, an internal thread connecting area is arranged at the top end of the second connecting piece, and the sampling probe (2130) is fixedly clamped at the bottom end of the second connecting piece (2133).
6. The soil gas quantitative passive detection system based on the balance principle of claim 5, wherein: the first connecting piece (212) is of a cover-shaped structure, a rubber sealing ring is arranged on the bottom side of the cover-shaped structure, the top of the cover-shaped structure is attached to the sinking groove of the pipeline connector (201), the bottom of the first connecting piece (212) is sequentially provided with a first threaded area and a second threaded area from top to bottom, the first threaded area is fixedly connected with the threaded area of the pipeline connector (201), and the second threaded area is fixedly connected with the internal threaded area of the second connecting piece (2133).
7. The soil gas quantitative passive detection system based on the balance principle according to claim 4, wherein: the passive sampling film (2132) needs to satisfy a balanced distribution coefficient of not more than 700 cm 3 And/g, effective diffusion coefficient is not less than 10 -7 cm 2 The material of the passive sampling film (2132) is selected from organic polymerAnd (3) a compound.
8. The soil gas quantification passive detection system based on the principle of equilibrium of claim 4 or 7, wherein: the passive sampling film (2132) needs to meet the requirements of 50-100 mm in length range, 3-5 mm in width range and not more than 1.5mm in thickness.
9. The method for using the soil gas quantitative passive detection system based on the balance principle according to any one of claims 1 to 8, which is characterized by comprising the following steps:
drilling a well hole, namely drilling the well hole at a designed detection point position to form the well hole;
step two, arranging a detection pipe (20), when a single-hole single-pipe detection process is selected, firstly drilling a well hole, stopping drilling after the well hole depth reaches a designed depth, and lifting a drilling tool after removing chips and residues in the well hole; filling clean quartz sand filter materials with the thickness of 5cm into the well hole, vertically filling a detection tube (20), and then continuously filling the clean quartz sand filter materials to the designed height around the detection tube (20) filled in the well hole to form a clean quartz sand filter material gas guide layer (10); adding clean water after filling clean dry bentonite with the thickness of 30cm at the top of the clean quartz sand filter material gas-guide layer (10) until the clean bentonite layer reaches the wellhead of the well hole to form a clean bentonite barrier layer (11), and finally filling cement mortar into the well hole to the ground to form a wellhead sealing layer (12); when the single-hole multi-pipe detection process is selected, firstly, drilling a well hole, stopping drilling after the well hole depth reaches the designed depth, and then lifting a drilling tool after removing debris and dregs in the well hole; filling clean quartz sand filter materials with the thickness of 5cm into the well hole, vertically burying the longest detection tube (20), and then continuously filling the clean quartz sand filter materials to the designed height around the longest detection tube (20) buried in the well hole to form a clean quartz sand filter material air guide layer (10); adding clean water after filling 30cm clean dry bentonite on the top of the clean quartz sand filter material air guide layer (10) until the clean dry bentonite is expanded by water absorption until the depth of a second long detection tube (20) is located, forming a clean quartz sand filter material with the thickness of Fang Zhuangtian cm on the clean bentonite blocking layer (11), vertically filling the second long detection tube (20), repeating the subsequent steps of the longest detection tube (20) until all detection tubes (20) are filled, sequentially paving the clean quartz sand filter material air guide layer (10) and the clean bentonite blocking layer (11) to the wellhead of a well hole, and finally filling cement mortar into the well hole to the ground to form a wellhead sealing layer (12);
step three, connecting a sampler (21), fixedly connecting the bottom end of a push rod (211) with a first connecting piece (212), fixedly connecting the top end of the push rod (211) with a T-shaped handle (210), fixing a pipeline to a middle device (214) at a corresponding position in the push rod (211), then placing a passive sampling film (2132) on a porous supporting plate (2131) obliquely arranged at the bottom of a sampling probe (2130), and then quickly fixedly connecting the passive sampling probe (213) with a second threaded area of the first connecting piece (212);
step four, assembling a passive soil gas detection assembly (2), installing a connected sampler (21) at the central position of a detection tube (20), ensuring that a passive sampling probe (213) passes through a threaded through hole arranged at the central position of a main body structure of a pipeline connector (201) to enter an air inlet screen tube (202) under the assistance of a push rod (211), then rotating a T-shaped handle (210) to fixedly connect a first threaded region in a first connecting piece (212) with a threaded connection region of the pipeline connector (201), and attaching the top of the first connecting piece (212) to a sinking groove of the pipeline connector (201); the T-shaped handle (210) is reversely rotated to be taken down from the pushing rod (211), and the pipeline sealer (203) is screwed into the top end of the real pipe (200) to seal the real pipe;
step five, sampling, namely unscrewing a pipeline sealer (203) after balancing 72 and h, mounting a T-shaped handle (210) on a pushing rod (211), loosening a first connecting piece (212) and a pipeline connector (201) by rotating the T-shaped handle (210), rapidly lifting the pushing rod (211) to lift a passive sampling probe (213) to the ground, taking the passive sampling probe (213) off, taking a passive sampling film (2132) out of the passive sampling probe (213) by using a cleaning tool, rapidly transferring the passive sampling film into a sealed glass bottle (31) with an adsorption tube (32) inside, and keeping a low-temperature environment to be sent to a laboratory;
step six, calculating the concentration of target pollutants in the soil gas, installing an adsorption tube (32) into a thermal desorption device, detecting the mass of the target pollutants adsorbed in the adsorption tube (32), and calculating the concentration of the target pollutants in the soil gas at the installation position of a passive sampling probe (213) by adopting the following formula:
wherein C is sg For the concentration of target pollutant in soil gas at the installation position of the corresponding passive sampling probe (213), mg/m 3 The method comprises the steps of carrying out a first treatment on the surface of the Mc is the mass of the target contaminant adsorbed in the adsorption tube (32), mg; m is M p G is the mass of the passive sampling film (2132); k (K) pg Equilibrium partition coefficient, cm, for target contaminants in soil gas in passive sampling membrane (2132) 3 /g。
10. The method for using the soil gas quantitative passive detection system based on the balance principle as claimed in claim 9, wherein the method comprises the following steps: the adsorption pipes (32) in the fifth step and the sixth step are filled with adsorbents, and the equilibrium adsorption distribution constant of the adsorbents is not less than 10 4 cm 3 /g, effective diffusion coefficient of not more than 10 -8 cm 2 /s。
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| CN103913354A (en) * | 2014-04-23 | 2014-07-09 | 中国地质大学（武汉） | Passive collection device and method for volatile organic pollutants in soil gas |
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