JP2003185540A - Apparatus for sampling soil gas sample, and gas sample- sampling method and gas-analyzing method using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus for sampling a soil gas sample and to provide a primary/secondary investigation method using the apparatus. <P>SOLUTION: An apparatus 40 for sampling a soil gas sample is loaded into the punched hole of the soil whose primary soil investigation is completed for sampling a gas sample. The apparatus 40 has a gas introduction section 36 that is formed by assembling a plurality of gas introduction pipes 33A-33C that are successively adjusted to be shorter from the length according to the maximum depth of a punched hole 60 for sampling a gas sample, a switching means 32 for selectively switching gas sampling from each introduction pipe for selecting a gas sample to be sampled, a gas chromatography apparatus connection section 31 connected to the switching means 32, and inflatable balloons 35A-35D that are provided as a gas-shielding means at a position between gas introduction openings 34A-34C of the gas introduction pipes 33A-33C. Then, the sampled gas sample is supplied to SAW/GC for analyzing a gas sample, thus performing the secondary investigation of the soil. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a soil gas sampling tool, a gas sampling method and a gas analysis method using the same, and more particularly to a volatile organic compound (hereinafter referred to as VO).
Soil gas sampling instrument suitable for conducting a quick and simple primary survey in the plane direction of the surface layer and secondary survey in the depth direction of a contaminated soil by (C)) and a gas sample using the same The present invention relates to a sampling method and a gas analysis method.

[0002]

2. Description of the Related Art In recent years, pollution of soil and groundwater due to various human activities has become apparent on a global scale. Due to inadequate disposal and storage of heavy metals, organic compounds, etc. used in the industrial production process, harmful substances derived from these pollute soil, which is topsoil, and the contamination penetrates into the ground, causing groundwater To contaminate. In some of the land, the fact of soil pollution is clear from the operation history of factories and business establishments, but in some cases, the fact of pollution is discovered by well water taken from existing wells. According to a survey conducted by organizations related to the Environment Agency, there are as many as 320,000 soil pollutants in Japan.
In such a soil pollution survey area, in addition to horizontal surveys such as grasping the extent of soil pollution at the site, it is necessary to measure and analyze the soil depth direction by boring surveys.

Generally, in the analysis of contaminated soil, the survey target area is divided into 10 or more places, and the soil of each division is analyzed. By measuring the soil at a point, the three-dimensional distribution of pollutants can be found, and the overall soil contamination status in the target area can be ascertained. Various survey methods have been implemented and proposed in the past.

Among these, the method using the underground exploration radar is
From the ground surface or in the air, three-dimensionally partitioned soil is sequentially scanned by block with an exploration radar, and the concentration of heavy metals present in the soil can be measured by the strength of the reflected waves, and the state of vertical pollution can be measured. It can be converted into a wide range of data. However, the VOC, which accounts for about 70% of groundwater pollutants caused by contaminated soil, does not react with the underground exploration radar, so it cannot be used for VOC measurement, according to a report of the Environment Agency.

A method for investigating soil pollution (Japanese Patent Laid-Open No. 2000-2000)
No. 9721 gazette), a soil gas sampling hole is formed, a soil gas sampling probe is moved to an arbitrary plurality of measurement positions at constant depth intervals, and the gas is sampled in a container, and the VOC concentration in the gas is measured. A method of measuring is proposed. However, in this method, in order to move the probe in the depth direction in the collection hole, it is necessary to provide a gap between the wall surface of the hole and the probe. The gases in the spaces located above and below, respectively, flow into and out of each other through the gap, and are mixed,
As a result, the measurement result becomes different from the actual VOC concentration at the measurement point, and there is a problem in the accuracy of measurement / analysis of soil contamination by VOC.

Further, in the above method, it takes at least 5 to 10 minutes for the VOC in the soil gas sampling probe and the VOC in the soil water around it to reach a vapor-liquid equilibrium state. Therefore, when there are a large number of measurement points in one sampling hole, a considerable amount of time is required, and there is a problem that it is difficult to determine the actual state of soil pollution due to VOC in real time.

In the method using a gas chromatography device (hereinafter, sometimes simply referred to as gas chromatography or GC) including the above method, the soil or soil gas at the measurement point is sampled in a predetermined container at the measurement site, This is brought back to the analysis room and used for measurement one sample at a time. In the gas chromatographic analysis, a separation column having a length of 15 to 60 m normally separates each component of VOCs in a mixed state in order according to the difference in retention capacity.
Since it is detected by a predetermined detector such as D or PID, the measurement time requires several tens of minutes per sample. Therefore, there is a drawback that a great deal of labor and time are required until the measurement result becomes clear.

Therefore, in the analysis of contaminated soil, etc., a portable gas chromatography device is used, which is brought to the measurement site and measured at the site. Silicon and PTFE (polyether) are put in the bored holes. A method has been adopted in which a tube made of tetrafluoroethylene) or stainless steel is inserted, a sample gas is collected in a Tedlar bag for collecting gas, and the collected sample gas is introduced into a portable gas chromatograph for analysis. Since the portable device uses a relatively short separation column of about 15 m, one sample can be measured
There is also an apparatus that can be performed in a short time of about 0 minutes.

However, since the portable device has low detection sensitivity, a photoionization detection / gas chromatography device (hereinafter referred to as P
(Also referred to as ID / GC) and the like. In addition, there is a limit to the reduction of measurement time per measurement point, and it is difficult to measure and analyze a wide range of soil pollution in real time. There is a problem that it is extremely difficult to complete all the measurements during the same day, because the number of measurement points is required to be several times that of the above. In addition, this method requires a large number of clean Tedlar bags in order to sample the Tedlar bag once, and the VOCs in the collected gas sample are adsorbed to the Tedlar bag, resulting in a lower measurement result than the actual concentration.
For example, there is a problem that only actual measured values of 50 to 80% can be obtained.

On the other hand, the surface acoustic wave detection / gas chromatography device (hereinafter, also referred to as SAW / GC) uses a highly sensitive crystal oscillator as a detector, so that the separation column can be shortened to 1 m or less. Significantly shorter than normal GC. Therefore, the time required for one measurement can be shortened to 10 to 70 seconds, which enables quick analysis. Therefore, in the analysis of contaminated soil gas, it has been required to develop a method of utilizing the superiority of SAW / GC to expand the range of application and improve the analysis accuracy.

[Patent Document 1] Japanese Patent Application Laid-Open No. 2000-009721

[0011]

The object of the present invention is to solve the above-mentioned problems of the prior art and to measure the two-dimensional and three-dimensional distribution of volatile organic compounds (VOC) in contaminated soil by measuring the plane direction of the soil. And a depth direction gas sampling and analysis accuracy can be improved, and a quick and simple measurement can be performed at a measurement site, and a soil gas sampling tool, and a gas sampling method and gas analysis method using the same To provide.

[0012]

Means for Solving the Problems As a result of intensive studies on the above problems, the inventors of the present invention have protected a gas sampling thin tube with a cylindrical guide member and have its tip opening inside a bored hole provided in soil. By using a gas sampling tool that can be fixed at a predetermined depth, gas samples can be collected quickly and easily even if there are many points to be measured, and a gas introduction means is simultaneously installed in each measurement space in the soil depth direction. The present invention has been accomplished by taking measures and by making each space a closed space, it is possible to prevent mixing of gas in the depth direction, and the present invention has been achieved as a means for solving the above problems. That is, the invention claimed in the present application is as follows.

(1) A soil gas sampling device for sampling a sample for soil gas analysis from the perforated soil,
A cylindrical guide that is narrower than the hole and has a closed bottom and a slit-shaped opening having a predetermined width that is provided along the length direction, and the closed bottom of the cylindrical guide is spaced apart by a predetermined distance. And a thin tube for gas sampling, which has a lower end opening at the upper end and extends above the upper opening along the central axis of the cylindrical guide.

(2) The soil gas sampling device according to (1) above, wherein the slit-shaped opening of the cylindrical guide is provided with a means for opening and closing the opening. (3) The above-mentioned (1) or (1), characterized in that a fixing plate having an enlarged diameter is provided in an upper opening of the cylindrical guide for fixing the cylindrical guide to an entrance of a hole provided in the soil. The soil gas sampling device according to 2).

(4) Surface acoustic wave detection / detection via the drain bottle at the upper end of the gas sampling thin tube of the soil gas sampling instrument according to any one of (1) to (3) above.
Gas chromatography device (SAW / GC) or gas ionization detection gas chromatography device (PID / G)
A soil gas sample analysis system characterized in that C) is connected.

(5) The soil gas sampling device according to any one of the above (1) to (3) is inserted into a perforation provided in soil and fixed at a predetermined depth, and then the closed bottom portion is formed. Characterized by collecting soil gas through a gas sampling thin tube opened at a predetermined distance above.
Soil gas sampling method.

(6) A soil gas analysis method using the soil gas analysis system according to (4) above, which comprises (1) above
The gas for opening the soil gas sampling instrument according to any one of (1) to (3) above, which is inserted into a perforation provided in the soil and fixed at a predetermined depth, and then separated from the closed bottom by a predetermined distance. Soil gas is collected through a thin tube for sampling, and the collected soil gas is introduced into the surface acoustic wave detection / gas chromatography device (SAW / GC) or photoionization detection gas chromatography device (PID / GC) to obtain soil gas. Volatile Organic Compounds (VOCs) included
A method for analyzing soil gas, which comprises measuring the amount.

(7) A soil gas sample collecting device for collecting a sample for soil gas analysis from perforated soil, the length of which is sequentially shortened from the length corresponding to the maximum depth of the perforation. A gas introduction part consisting of a plurality of gas introduction pipes arranged in such a manner as to be provided at the upper end of the gas introduction part, and to selectively switch the gas sampling from each gas introduction pipe for selecting the gas sample to be collected And a gas analyzer connecting portion connected to the switching means, and a gas shutoff means is provided at a position between the gas introduction ports of the gas introduction pipes of different lengths in sequence. A soil gas sampling tool.

(8) The soil gas sampling device according to (7) above, wherein the gas shielding means has an inflatable balloon. (9) The instrument for soil gas sampling according to (7) or (8) above, wherein the gas introducing pipe has an inner diameter of 0.1 mm to 8 mm.

(10) A gas connected to the soil gas sampling device according to any one of (7) to (9) above and the analyzer connecting portion provided in the soil gas sampling device. A soil gas analysis system comprising a surface acoustic wave detection / gas chromatography device (SAW / GC) for performing an analysis.

(11) Using the soil gas sampling device according to any one of (7) to (9), the gas introduction part of the device is inserted into a gas sampling hole previously drilled in the soil. Then, holding the gas introduction portion so that the gas introduction port is located at the gas introduction position, and then actuating the gas shielding means to form a closed space by blocking the vertically adjacent gas introduction ports, Next, a method for sampling soil gas, characterized in that gas is sampled from the closed space through the gas introducing pipe by the switching means.

(12) Using the soil gas analysis system described in (10) above, the gas introduction part of the instrument is inserted into the gas sampling hole in advance, and the gas introduction port is located at the gas introduction position. The gas introducing portion is held so as to be positioned, and then the gas shielding means is operated to cut off the vertically adjacent gas introducing ports to form a closed space, and then the switching means is used to move the closed space from the closed space. A method for soil gas analysis, which comprises collecting gas through a gas introducing pipe, introducing the collected gas sample into the SAW / GC, and analyzing the amount of volatile organic compounds (VOC) in the gas sample.

(13) According to the soil gas analysis method described in (6) above, the soil subjected to the primary soil survey for obtaining the distribution of volatile organic compounds (VOC) in the plane direction of the soil surface layer is subjected to the above (12). A soil gas analysis method, which comprises performing a secondary soil survey for obtaining a volatile organic compound (VOC) distribution in a soil vertical direction by the soil gas analysis method described.

That is, one invention of the present application uses a gas sample collecting instrument having a cylindrical guide and a sampling thin tube provided along the central axis of the cylindrical guide and opening upward at a predetermined distance from the bottom. Gas sample of the soil surface layer is collected, and the above-mentioned means and SAW / GC or PID /
By using GC together, it is possible to perform a quick and easy measurement (primary survey) of the planar distribution of VOCs at the measurement site of contaminated soil.

Further, another invention of the present application is a gas introducing means formed by assembling a plurality of gas introducing pipes having different lengths in order to simultaneously collect soil gas from different measurement target spaces in the depth direction. In order to prevent mixing of gas in the depth direction by making each space a closed space, it is possible to improve the accuracy of contaminated soil gas analysis by providing a gas blocking means between the gas inlets. In addition, by using the above means and SAW / GC in combination, it is possible to perform a quick and simple measurement (secondary survey) of the vertical distribution of VOCs at the measurement site of contaminated soil.

[0026]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will now be described in more detail with reference to the drawings. FIG. 1 is an explanatory view showing a soil gas sampling device which is an embodiment of the present invention and is suitable for performing a primary survey in the plane direction (surface layer portion) of soil. Figure 1
In this device, a cylindrical guide 5 having a closed bottom 9 and a slit-shaped opening 10 having a predetermined width along the length direction, and the closed bottom 9 of the cylindrical guide 5 are separated by a predetermined distance. It is mainly composed of a gas sampling thin tube 6 having a lower end which is spaced apart and opened above and extending along the central axis of the cylindrical guide 5 to above the upper opening. 1 is a gas chromatography connection pipe, 2 is a drain bottle, 3 is a handle, 4 is a fixing plate provided in the upper opening of the cylindrical guide 5, 7 is a support member for the sampling thin tube 6, and 8 is It is a dust filter. In addition, the cylindrical guide 5 is configured to be thinner than the inner diameter of the perforation provided in the soil.

FIG. 2 is a soil gas analysis system of the present invention in which the gas sampling thin tube 6 of the soil gas sampling instrument of FIG. 1 is connected to, for example, a SAW / GC via a drain bottle 2 and a gas chromatography connection tube 1. It is a figure which shows an example. In FIG. 2, the SAW / GC (12) is a mobile generator 16
It is mounted on a carrier truck 15 provided with a carrier controller 15 and a personal computer (PC) 14 for displaying analysis results.

When the primary investigation for investigating the contamination situation of the soil surface layer portion is carried out by using the soil gas analysis system having such a constitution, first, the gas sampling tool shown in FIG. 1 is drilled in the soil. , And the fixture plate 4 is fixed by the fixing plate 4 so as not to drop to the lowermost part of the perforation, and then the sample gas is sampled through the sampling thin tube 6. The sample gas sampled is passed through a thin tube 6, a drain bottle 2 and a gas chromatograph connecting tube 1, and SAW / GC as an analyzer.
Where VOC concentration in the sample gas is measured,
The analysis result is sent to the personal computer 14 and displayed. Next, the soil gas sampling device is sequentially loaded into another perforation, the same gas sample is sampled and analyzed, and the VOC distribution in the plane direction is obtained.

According to the present embodiment, the sample inlet of the soil gas sampling device (sampling thin tube) is loaded into the soil perforation to be surveyed to collect the gas sample, and the highly sensitive portable gas chromatograph such as SAW is used. By carrying / GC to each measurement point to measure the VOC amount in the gas sample, one measurement time can be shortened to 15 to 70 seconds and an efficient primary survey can be performed. In addition, surface acoustic wave detection /
Gas chromatography device (surface acoustic wave)
Since the sample gas requirement is as small as 1 to 30 mL, VOC concentration can be measured by directly sucking the gas at the bottom of the boring hole, and the column length is as short as 1 m.
Can be almost separated at the ppb level (although there are some overlapping if they exist at the same time).

[0030] Generally, investigation of the distribution of contaminated soil (primary investigation)
Since the target is soil gas at a depth of 0.5 to 1 m in the surface layer (planar direction), a boring hole (perforation) with a diameter of 20 to 50 mm is dug to a depth of about 0.6 to 1.1 m. Therefore, in the present embodiment, the length of the cylindrical guide 5 of the soil gas sampling device is, for example, 0.55 to 1.2 m, and the outer diameter is, for example, 10 to 50 mmφ.
For example, when the boring hole is 30 mmφ, the outer diameter is 25 mmφ which is slightly smaller (0.5 cm) than the boring hole, the plate thickness is, for example, 0.2 to 3 mm, and the opening ratio is, for example, 10 to 50%. It As a material for the cylindrical guide, for example, stainless steel is preferably applied.

Further, it is preferable that the cylindrical guide 5 is provided with an opening / closing means for completely sealing the slit-shaped opening 10. As the opening / closing means, for example, another cylinder having the same length (the outer diameter is smaller than the outer inner diameter) is provided inside the cylindrical guide, and this is rotated to open / close the opening, or the cylindrical shape is used. A method in which another short cylinder (having a length of 1/2 or less of the cylindrical guide and an outer diameter smaller than the inner diameter of the cylindrical guide) of the guide 5 is provided inside the guide 5, and is slid up and down by a support pillar to open and close The following are listed.

When collecting a gas sample by using the soil gas sample collecting instrument having the opening / closing means provided in the slit-shaped opening 10, first, the slit-shaped opening 10 is closed by the opening / closing means, and in this state, perforation is performed. After inserting, mounting and fixing the instrument to the perforation by the fixing plate 4, the slit-shaped opening 10 is opened by the opening / closing means, and in this state, the gas sample is collected through the sampling thin tube 6.

In the present embodiment, the cylindrical guide 5 is provided with a closed bottom 9 in order to prevent the inflow of the leachate accumulated at the bottom of the perforation. However, a large amount of leachate is released during the measurement. A drain bottle 2 is provided immediately in front of the gas chromatograph connecting portion 1 in order to prevent the gas chromatograph from being sucked into the gas sampling thin tube 6. If the capacity of the drain bottle 2 is too large, the amount of empty suction gas increases and the suction time becomes longer, so the capacity of the drain bottle 2 is preferably 20 mL or less.

In this embodiment, since the cylindrical guide 5 is fixed to the upper opening of the cylindrical guide 5 at the upper end of the perforation provided in the soil, the outer diameter of the cylindrical guide 5 is smaller than that of the cylindrical guide 5. For example, the fixed plate 4 having a diameter of 40 mm or more is provided.
Instead of the expanded fixed plate 4, for example, 10 to 20 mm in length and 20 to in width
Two or more rectangular plates with a thickness of 50 mm and a thickness of 1 to 5 mm may be provided.

In the present embodiment, the thin tube 6 for gas sampling has, for example, an inner diameter of 0.1 to 2 mmφ and an outer diameter of 1 to 5 mmφ.
For example, a thin tube made of PTFE (polytetrafluoroethylene), silicon or stainless steel is used. The distance between the lower opening of the sampling thin tube 6 and the closed bottom 9 of the cylindrical guide 5 is, for example, 50 to 100 mm. It is preferable to provide a dust filter in the lower opening of the sampling thin tube 6 in order to prevent the dust generated in the hole from flowing in.

In this embodiment, it is preferable that the connecting portion between the gas chromatograph connecting pipe 1 and the gas chromatograph (SAW / GC) is of Luer lock type. In this example,
A photoionization detection gas chromatography device (PID / GS) can also be used as the gas chromatograph. PID / GS requires a small amount of sample gas of 1-2 mL, the column length is slightly short at 15 m (hence the analysis time is 5-10 minutes), and 11 types of VOC water quality control except carbon tetrachloride are almost at ppb level. They can be separated (although if they are present at the same time, some may overlap). Therefore, this also enables a quick analysis.

In this embodiment, since SAW / GC or PID / GS is used as the analyzer, the representative point of the target soil, for example, the soil or gas at the center of the measurement range is 1 to several. Point sampling and take-back, identification of detected VOC by high-precision analyzer (MS / GC: gas chromatography / mass spectrometer), etc. (Pollution V detected at the same retention time
It is preferable that VOC other than OC) is performed.

In the present invention, when the primary survey of soil pollution is completed and there is one or more contaminated points, the secondary distribution of the contamination distribution including the depth direction results in the contamination within the specified range. It is preferable to consider soil modification / immobilization treatment. For example, when conducting a primary survey in a mesh pattern at intervals of 10 m and there is a single point contaminated with trichlorethylene, that point and its surrounding measurement points (no pollution)
A new secondary survey point of 4 to 8 points (mesh pattern) will be set in the middle of. Next, a polling point and secondary inspection points 4 to 8 points, 5 to 9 points in total, were newly drilled using a boring machine to a depth of, for example, 5 m. / SAW is installed and the jig for contamination measurement is partitioned by a rubber balloon at intervals of 0.5 m, and the concentration of trichlorethylene at each position is measured.
Sequentially measure in the same way at each of 5 to 9 points, for example, the concentration distribution of trichlorethylene is expressed three-dimensionally in the plane direction and the depth (vertical) direction, and the modification / immobilization range of contaminated soil is determined. .

FIG. 3 is an external view showing another embodiment of the soil gas sampling device of the present invention. In the figure, the soil gas sampling device 40 is used when investigating the contamination state of the soil in the depth direction, and is a gas sampling hole for introducing soil gas as a sample for analysis. Gas introduction pipes 33A, 33B, and 33C arranged so that the lengths are sequentially shortened from the length corresponding to the maximum depth of
And a switch for selectively switching the gas sampling from each of the gas introducing tubes 33A, 33B, and 33C for selecting the gas sample to be sampled, which is provided at the upper end of the gas introducing section 36. Means 32, and a GC device connecting portion 3 for connecting a gas chromatography device (not shown) connected to the switching device 32 and the present instrument 40.
1 and the gas introduction pipes 33A, 33 having different lengths in sequence.
B and 33C are mainly constituted by inflatable and inflatable balloons 35A, 35B, 35C and 35D as gas blocking means provided at positions between the gas inlets 34A, 34B and 34C.

In FIG. 3, the number of the gas introducing pipes constituting the gas introducing portion 36 provided in the device 40 is three, but the figure is an example of the present invention, and the soil gas sampling of the present invention is performed. The appliance 40 is not limited by the number of the gas introduction pipes. Similarly, the number of balloons 35A etc. as the gas shielding means provided in the device 40 is four,
The figure is an example of the present invention, and the soil gas sampling device 40 of the present invention is not limited by the number of the gas shielding means.

The inner diameter of the gas introducing pipe 33A or the like is preferably in the range of 0.1 to 8 mm, more preferably in order to reduce the dead volume and shorten the time required to introduce the gas into the GC. It is 0.1 to 2 mm.
If the inner diameter is less than 0.1 mm, the gas introduction pipe 33A or the like may be clogged with small particles of soil or dust, while if it exceeds 8 mm, the dead volume becomes large, and the measurement target is sealed. The space becomes a vacuum. For example, the volume of a space with a section length of 90 cm provided in a gas sampling hole having a depth of 5 m and a diameter of 20 mm is about 283 cm ^3, but the space between the gas introduction port of the gas introduction pipe and the GC is inserted into the space. When the distance is 5 m, the dead volume of the gas introduction pipe having an inner diameter of 8 mm is about 251 cm ^{3 which} is almost equal to the space volume, and the space is almost vacuumed by the gas introduction.

On the other hand, in this case, when the inner diameter is 2 mm, the dead volume of the gas introducing pipe becomes about 15.7 cm ³ , and it is possible to avoid the vacuum of the space to be measured,
It takes about 30 seconds to reach the GC. Since the analysis time by GC is 10 to 70 seconds, the total required measurement time from gas sampling to the end of analysis is 40 to 100 seconds. It is desirable not to exceed this for quick measurements. Therefore, the maximum length from the gas inlet to the GC is 5
In the case of about m, it is more desirable that the inner diameter of the gas introduction pipe is 2 mm or less.

The outer diameter of the gas introducing pipe 33A or the like is preferably in the range of 0.4 to 10 mm, and more preferably in order to prevent the volume of the gas to be analyzed in the gas sampling hole from becoming too small. Is 0.4 to 4 mm. Outer diameter is 1
If it exceeds 0 mm, it becomes impossible to insert three or more gas introduction pipes into a perforation having a diameter of 20 mm. On the other hand 0.4 mm
When it is less than the above range, the gas passage is easily deformed by a small stress, and the gas flow passage in the gas introduction pipe may be blocked by the deformation.

As the switching means 32, for example,
A flow path switching valve or a flow path switching valve can be used, but the soil gas sampling device 40 of the present invention is not limited by the switching means 32.

Inflatable and deflatable balloon 3 as the gas shielding means
When 5A or the like is used, the balloon 35A or the like is fed with air,
A balloon inflation / expansion means such as a foot pump 38 for inflating / deflating by extraction, and a balloon inflation / expansion means such as the foot pump 38 for communicating the balloons 35A etc. with the balloon inflation / expansion means such as the foot pump 38. Connected flexible tube 37S,
It is possible to provide a balloon 35A or the like in communication with the flexible pipe 37S, and to provide a straight pipe 37T attached to the gas introducing portion 36. The balloon 35A and the like, the straight pipe 37T, the flexible pipe 37S, and the foot pump 38 are in communication with each other so that air can move inside. Further, a valve 37U for controlling the expansion and contraction of the balloon 35A is provided upstream of the straight pipe 37T.
Is provided.

The intervals at which the balloons 35A and the like are provided can be constant. By making the interval constant, the volume of the closed space 55A formed by the balloons 35A and the like can be made constant.

As the material of the balloon 35A and the like, in addition to rubber, expandable and contractible plastic or the like can be used.
The surface of the balloon 35A or the like may be coated with a Tedlar bag, which is a bag, with a fluororesin or a material having low reactivity in order to prevent VOC adsorption.

The gas shielding means shuts off between vertically adjacent gas inlets 34A and the like at positions between the gas inlets 34A and the like of the gas inlet pipes 33A and the like having different lengths to form a closed space. Any means can be used as long as it can be formed. Therefore, the inflatable and deflatable balloon 35A and the like are examples, and the soil gas sampling device 40 of the present invention is not limited by the gas shielding means.

For example, as the gas shielding means, the gas introducing portion 36 is in a folded state when it is inserted into the gas sampling hole 60, while the gas introducing portion 36 is in the folded state when the gas is introduced into the gas introducing portion 36. It is also possible to use an umbrella-shaped device that is deployed so as to form the closed space 55A or the like therein.

FIG. 4 is an explanatory view showing an embodiment in which a sample is sampled by using the soil gas sampling tool shown in FIG. 3 and the soil gas is analyzed. In the figure, the present system shows the soil gas sample collecting device 40 for collecting a gas sample to be used for contaminated soil gas analysis, and the gas chromatography device connection part 31 provided in the soil gas sample collecting device 40.
It is mainly composed of a surface acoustic wave detection / gas chromatography (SAW / GC) device 43 for gas analysis, which is connected to. The SAW / GC device 43 is mounted on a carriage 45 for carrying the system to each contaminated soil measurement point.

In FIG. 4, in the soil gas sample collecting device 40 of the present invention, the gas introducing portion 3 of the device 40 is inserted into the gas sample collecting hole 60 which is previously drilled in the soil 50.
6 is inserted, and the gas introduction part 36 has the gas introduction port 34
A, 34B, and 34C are held in the gas introduction position and then in FIG.
The gas shielding means, shown as 5B, 35C and 35D, are actuated to actuate vertically adjacent gas inlets 3
4A, 34B, and 34C are cut off to provide a closed space 5
5A, 55B, and 55C are formed, and each enclosed space 5
Gases present in 5A, 55B, and 55C are introduced into the gas introduction pipes 33A, 33B, and 33C from the gas introduction ports 34A, 34B, and 34C, and are introduced into the respective gas introduction pipes 33A, 33B, and 33C. The collected gas is collected through the gas introducing pipes 33A, 33B, and 33C by the switching means 32 provided at the inlet of the gas introducing section 36 so that the sampling is selectively switched. The gas is supplied to the GC as a sample gas to be analyzed through the GC device connection section 31.

In FIG. 4, the inflatable and deflatable balloons 35A, 35B, 35C and 35D as the gas shielding means are
The gas introduction part 36 is inserted into the perforation 60 in a contracted state in which air is not introduced into the gas introduction part 36.
Is held such that the gas inlets 34A, 34B, and 34C are positioned at the gas inlet position, and then each balloon 35A is inserted through the flexible pipe 37S and the pipe 37T.
The foot pump 38 in communication with 35B, 35C, and 35D is actuated to actuate each balloon 35A, 35B, 35C,
And air is sent to 35D and each balloon 35A etc. is expanded. At this time, the valve 37U provided on the straight pipe 37T is opened. Each inflated balloon 35
Closing the perforations 60 with A, 35B, 35C, and 35D allows the gas introduction ports 34A, 34A to be closed.
Respective enclosed spaces 55A, 55B, and 55C in which B and 34C are independently contained are formed.

When the closed space 55A or the like is formed, the valve 37U is closed, air is introduced into the balloon 35A or the like to maintain the expanded shape, and the closed space 55A or the like is maintained.
The state in which the etc. are formed is maintained. In this state, soil gas sampling and gas analysis are performed.

Further, the inflated balloon 35A or the like presses the inner wall surface 61 of the perforation 60, and the reaction thereof causes the balloon 35A or the like to be pressed by the inner wall surface 61 around the periphery thereof, so that the position of the gas introducing portion 36 in the depth direction is changed. Fixed. That is, soil gas sampling and gas analysis can be performed without moving the gas introducing pipe up and down in a state where the gas introducing port 34A of the straight pipe 37T provided with the balloon 35A is fixed in the depth direction position. Done.

At the end of the measurement, the valve 37U is opened and the air in the balloon 35A or the like is evacuated so that the balloon 35A
Etc., the respective closed spaces 55A, etc. are opened, and the balloons 35A, etc., and the position of the gas introduction part 36 in the depth direction are released, and the gas introduction part 36 is opened by the perforation 6
The soil gas analysis system can easily be moved to the next measurement hole.

Each of the closed spaces 55A, 55B, and 55C formed by the gas blocking means is blocked between other vertically adjacent closed spaces to prevent gas from flowing in and out, and the uppermost closed space. The space 55A may be shielded from the ground space opened by the balloon 35A, and the closed space 55C at the bottom may be shielded from the bottom of the perforation 60 by the balloon 35D.
In this case, it is possible to prevent the gas from flowing into and out of the space other than the space to be measured.

The gas sample collected by the soil gas sample collecting device 40 constituting the present system is the GC connection part 31.
The SAW / GC43 connected to the
43 is repeated, and by repeating this, a vertical survey (secondary survey) is conducted on the soil to be surveyed.

[0058]

EXAMPLES Next, specific examples of the primary soil survey according to the present invention will be described. Example 1 As the cylindrical guide 5, a stainless steel cylindrical body having an outer diameter of 25 mmφ and an inner diameter of 21 mmφ, 15 × 50 m at a position 5 to 55 cm from the lower end thereof.
Using a slit-shaped opening 10 of m at two locations facing each other, the sampling thin tube 6 has an inner diameter of 0.25 mmφ,
A stainless steel pipe having an outer diameter of 1.25 mmφ and a length of 1200 mm, which was welded and fixed by a supporting member 7 at positions of 200 mm from the upper and lower ends of the cylindrical guide 5, was used. From the upper opening of the
Bend at a right angle (90 °) so that it is horizontal at the top of 100 mm, and at a right angle to point vertically downward at 100 mm ahead PT
Using the soil gas sample analysis system of FIG. 2 connected to the drain bottle 2 via a lid made of FE (polytetrafluoroethylene), points (15 × 20 = 300) in a mesh shape at intervals of 10 m from each of the four corners. The location of each of these 300 points is measured, and the positioning of SAW / GC warming operation (about 20 minutes) is performed on the rectangular land 150m in length and 200m in width that has been drilled to a diameter of 3cm and a depth of 1m before gas chromatography measurement. ), The soil contamination survey was conducted to measure the VOC at a depth of 900 mm at each point.
(Average time for each process) is about 1 minute for 10m movement, 5 seconds for sample inlet setting, 15 seconds for SAW / GC measurement, 1 minute 20 seconds (80 minutes in total)
(Seconds / location), and measurement at 300 points was completed in 6 hours and 40 minutes.

Comparative Example 1 For the same land as in Example 1, the same number of measuring points were set, measurement positioning and SAW / GC warm-up operation (about 90 minutes).
After performing the above, attach a 1.5 m long, for example, PTFE (polytetrafluoroethylene) tube (inner diameter 4 mm, outer diameter 6 mm) to the pump and put it in the bored hole to a depth of about 900 mm.
5L of gas from the measurement point to the Tedlar bag at a flow rate of 1
Collected at L / min (time required: 5 minutes). When the amount of VOC in each trapped gas was analyzed using SAW / GC, the required time (average time for each process) was about 1 minute per 10 m movement, sampling to a Tedlar bag was 5 minutes, and SAW / GC measurement 15
In a total of 6 minutes and 15 seconds (375 seconds / location), the measurement time was 8 hours and only 75 locations were measured. Until measurement is completed at all 300 points 4
It took days.

Next, a concrete example of the secondary soil survey according to the present invention will be described. Example 2 A stainless steel pipe having an outer diameter of 0.8 mm and an inner diameter of 0.25 mm was cut into lengths of 2.5 m, 1.5 m, and 0.5 m to form gas introduction pipes, which were assembled into a gas introduction portion. did. A three-way switching valve was provided at the inlet of the gas introduction part, and a swage lock type GC connection part having an inner diameter of 3 mm was welded (or silver brazed) to the valve. On the other hand, an opening is provided at an end of a stainless pipe with an outer diameter of 2 mm, an inner diameter of 1.4 mm, and a length of 3 m, each end being closed, 1 m, 2 m, and 3 m from the end, a total of 4 positions, A rubber balloon was attached so as to communicate with the inside of the pipe through each of the openings to form a gas shielding means. A foot pump for feeding air into the balloon was connected to the gas cutoff means. The gas shut-off means part was attached to the gas introduction part with the end part facing down to obtain a soil gas sampling tool. This instrument was connected to the SAW / GC via the GC connection part to make a soil gas analysis system.

Using this soil gas analysis system, the primary survey was completed and it was determined that a secondary survey was necessary.
The soil contamination distribution was measured as follows for a rectangular land of m and 200 m in width. That is, first, measurement points were determined in a mesh shape at intervals of 50 m from the four corners of the rectangle, and each measurement point was preliminarily bored to have a diameter of 2 cm and a depth of 3 m before measurement. In the depth direction, depths of 2.5 m, 1.5 m, and 0.5 m are set for a total of 3 measurement points, 5 in the horizontal direction and 4 in the vertical direction, for a total of 6 points.
0 measurement points were set. The measurement point was set in the morning and the SAW / GC warm-up operation was performed for about 20 minutes, and the measurement was sequentially performed from the afternoon.

The measurement was carried out by inserting the gas introduction part of the gas sampling tool into the hole and installing the end of the stainless steel pipe of the gas cut-off means at the bottom of the hole so that the gas introduction port was located at the gas introduction position. Next, operate the foot pump to inject air into each rubber balloon to inflate it, block the gas inlets vertically adjacent to each other to form a closed space, and control valve installed on the top of the stainless steel pipe. Closed to maintain the shape of each rubber balloon to maintain a closed space, and then, from each closed space, soil gas is sampled through each gas introduction pipe by a three-way switching valve, and the collected gas sample is SAW / GC. Offer, SA
Gas samples were analyzed by W / GC. After the completion of the analysis, the control valve was opened to deflate each rubber balloon, the gas introduction part was extracted from the perforation, moved to the next measurement point, and the measurements were performed sequentially.

At the time of measurement, the volume of the closed space to be measured is about 283 cm ³ , and the dead volume in the longest 2.5 m tube among the three gas introduction tubes is about 0.123 cm ³ . there were. Since the gas suction rate of SAW / GC was 30 cm ³ / min, the gas collected by the 2.5 m gas introduction tube reached SAW / GC within 1 second.

When the gas introduction pipe having a depth of 0.5 m is first switched and the measurement is started by pressing the SAW / GC measurement button, the sample gas is introduced into the SAW / GC by the small pump incorporated in the SAW / GC. After 60 seconds, the measurement result was displayed on the screen of the personal computer as the analysis device by the SAW / GC control software. Then, the gas introduction pipe was switched in the order of depths of 1.5 m and 2.5 m for measurement. The time required for measurement at the three measurement points set for one perforation was 3 to 4 minutes, and the time required for measurement at 20 ground measurement points, a total of 60 measurement points was about 2 hours. . Comparative Example 2 Soil gas was collected in a Tedlar bag having a volume of 5000 cm ³ , and a portable PID / GC was used to obtain Example 1.
The soil gas of the same land was measured. The measurement points were set in the morning and the PID / GC warm-up operation was performed for about 90 minutes, and the measurement was started in the afternoon. The pump has an inner diameter of 4 mm,
A polytetrafluoroethylene tube with an outer diameter of 6 mm and a length of 3 m was attached, and the polytetrafluoroethylene tube was inserted into the bored hole to set the depth direction to 2.5 m, 1.5 m, and 0.5 m. soil gas 5000 cm ³ in Tedlar bag from the measurement points three points were collected at a flow rate of 1000 cm ³ / min. The time required for collection was 15 minutes.

Portable gas PID / GC for each collected gas
Was analyzed using. The time required to measure the three measurement points set for one drilling was 30 to 40 minutes, and the measurement could be completed in about 4 hours until sunset. There were only measurement points at some points.

[0066]

According to the invention described in claim 1 of the present application,
In addition to preventing clogging and water suction due to the tip of the sampling thin tube coming into contact with the soil on the inner wall of the hole, gas samples can be collected efficiently, and the Tedlar bag is not required.
According to the invention described in claim 2 of the present application, in addition to the effects of the above invention, it is possible to more reliably prevent the sampling thin tube from being blocked and water from being sucked.

According to the invention of claim 3 of the present application, in addition to the above invention, the opening of the sampling thin tube can be easily fixed to a predetermined depth of the perforation. Claim 4 of the present application
According to the invention described in (1), it is possible to carry out the primary investigation in the plane direction of the surface layer of the soil quickly and stably by performing highly accurate analysis on site without returning the sample gas or the soil.

According to the invention of claim 5 of the present application, the gas sample of the soil surface layer can be efficiently collected.
Therefore, even if there are many measurement points, it is possible to sufficiently deal with the situation. According to the invention of claim 6 of the present application, since the sampling process is shortened, the primary investigation based on the gas sample in the soil surface layer portion can be performed quickly and easily.

According to the invention of claim 7 of the present application, in the measurement of the three-dimensional distribution of volatile organic compounds (VOCs) in the contaminated soil, gas collection in the depth direction of the soil is prevented. You can According to the invention described in claim 8 of the present application, in addition to the effects of the above invention, gas mixing can be reliably prevented by a simple device.

According to the invention of claim 9 of the present application, in addition to the effects of the above invention, the dead volume is reduced, and
The time required to introduce gas into C can be shortened. According to the invention of claim 10 of the present application, in the measurement of the three-dimensional distribution of volatile organic compounds (VOC) in the contaminated soil, gas mixing is prevented in the depth direction of the soil, and the sample is collected on the spot. Can be analyzed efficiently.

According to the invention of claim 11 of the present application,
A gas sample can be quickly collected by preventing gas mixing in the depth direction of soil.

According to the invention of claim 12 of the present application,
In the measurement of the three-dimensional distribution of volatile organic compounds (VOC) in contaminated soil, it is possible to prevent gas mixing in the depth direction of the soil, collect the sample, and analyze it efficiently on the spot. Further, it is possible to judge the analysis result and issue an instruction for the next measurement point, for example. According to the invention of claim 13 of the present application, not only the primary survey (surface layer) of the contaminated soil, but also the secondary survey (depth direction), the required period is greatly shortened Can correspond to.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a soil gas sampling tool according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing an example of a soil gas analysis system for primary investigation according to the present invention.

FIG. 3 is an explanatory view showing a soil gas sampling device showing another embodiment of the present invention.

FIG. 4 is an explanatory diagram showing a soil gas analysis method using the soil gas sampling tool of FIG. 3.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Gas black connection pipe, 2 ... Drain bottle, 3 ... Handle, 4 ... Fixed plate, 5 ... Cylindrical guide, 6 ... Sampling thin tube, 7
... Support member, 8 ... Dust filter, 9 ... Closed bottom part, 1
0 ... Slit-shaped apertures, 12 ... SAW / GC, 13 ... Truck control device, 14 ... Data display personal computer, 15 ... Transport truck, 16 ... Mobile generator, 31 ... Gas chromatography device connection, 32 ... switching means,
33A, 33B, 33C ... Gas introduction pipes, 34A, 34
B, 34C ... Gas inlet, 35A, 35B, 35C, 3
5D ... Balloon, 36 ... Gas introduction part, 37S ... Flexible tube,
37T: straight pipe, 37U: control valve, 38: foot pump,
40 ... Soil gas sampling tool, 43 ... SAW / GC,
45 ... Transport dolly, 50 ... Soil, 55A, 55B, 55
C ... Closed space, 60 ... Perforations for gas sampling, 61 ... Perforated inner wall.

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 2G047 AA01 AA10 AD02 BC02 BC14                       CB03 EA10 GA18                 2G052 AA19 AB11 AC01 AC04 AD02                       AD42 BA14 BA28 CA04 CA22                       GA27 JA16

Claims (13)

[Claims] 1. A soil gas sample collecting device for collecting a sample for soil gas analysis from a perforated soil, which is a slit-shaped opening having a predetermined width and is provided along a closed bottom portion and a length direction. A cylindrical guide thinner than the perforated portion having a portion, and the closed bottom of the cylindrical guide has a lower end that opens upward at a predetermined distance, and the upper part along the central axis of the cylindrical guide. A soil gas sampling instrument, comprising: a gas sampling thin tube extending above the opening. 2. The soil gas sampling device according to claim 1, wherein the slit-shaped opening portion of the cylindrical guide is provided with a means for opening and closing the opening portion. 3. A fixing plate having an expanded diameter is provided in an upper opening of the cylindrical guide, and the fixing plate fixes the cylindrical guide to an entrance of a hole provided in the soil.
Alternatively, the soil gas sampling instrument according to item 2. 4. A surface acoustic wave detection / gas chromatography device (SAW / GC) through a drain bottle at the upper end of the gas sampling thin tube of the soil gas sampling instrument according to claim 1. ) Or a photoionization detection gas chromatography device (PID / GC) is connected to the soil gas analysis system. 5. The soil gas sampling device according to any one of claims 1 to 3 is inserted into a perforation provided in soil and fixed at a predetermined depth, and then separated from the closed bottom by a predetermined distance. A soil gas sampling method, comprising collecting soil gas through a gas sampling thin tube that opens above. 6. A soil gas analysis method using the soil gas analysis system according to claim 4, wherein:
Insert the soil gas sampling instrument according to any one of the above into the perforation provided in the soil, and after fixing at a predetermined depth, through the gas sampling thin tube that opens at a predetermined distance from the closed bottom portion. Volatility contained in soil gas by collecting soil gas and introducing the collected soil gas into the surface acoustic wave detection / gas chromatography device (SAW / GC) or photoionization detection gas chromatography device (PID / GC) A soil gas analysis method, which comprises measuring the amount of an organic compound (VOC). 7. A soil gas sample collecting device for collecting a sample for soil gas analysis from perforated soil, the length of which gradually decreases from the length corresponding to the maximum depth of the perforation. And a gas introduction part composed of a plurality of gas introduction pipes arranged in such a manner as to be provided at the upper end of the gas introduction part, for selectively switching the gas sampling from each gas introduction pipe for selecting a gas sample to be collected. It has a switching means and a gas analyzer connecting portion connected to the switching means, and a gas blocking means is provided at a position between the gas introduction ports of the gas introduction pipes of different lengths in sequence. , Soil gas sampling equipment. 8. The soil gas sampling device according to claim 7, wherein the gas shielding means has an inflatable and deflatable balloon. 9. The inner diameter of the gas introduction pipe is from 0.1 mm to
The soil gas sampling instrument according to claim 7 or 8, characterized in that it is 8 mm. 10. A gas analyzer for soil gas sampling according to any one of claims 7 to 9, and a gas analyzer connected to the analyzer connecting portion provided on the soil gas sampling device. Soil gas analysis system comprising the surface acoustic wave detection / gas chromatography device (SAW / GC). 11. The soil gas sampling device according to claim 7, wherein the gas introduction part of the device is inserted into a gas sampling hole previously drilled in the soil, The gas introduction part is held so that the introduction port is located at the gas introduction position, and then the gas shielding means is operated to interrupt the vertically adjacent gas introduction ports to form a closed space, and then the closed space Gas is collected from the space through the gas introduction pipe by the switching means,
Soil gas sampling method. 12. The soil gas analysis system according to claim 10, wherein the gas introducing portion of the device is previously inserted into the gas sampling hole so that the gas introducing port is located at the gas introducing position. The gas introducing portion is held, and then the gas shielding means is operated to shut off vertically adjacent gas introducing ports to form a closed space, and then the gas introducing pipe is switched from the closed space by the switching means. A method for soil gas analysis, in which a gas sample is collected through, the sampled gas sample is introduced into the SAW / GC, and the amount of volatile organic compounds (VOC) in the gas sample is analyzed. 13. A volatile organic compound (VO) in a plane direction of a soil surface layer portion by the soil gas analysis method according to claim 6.
C) The soil subjected to the primary soil survey for obtaining the distribution is subjected to the secondary soil survey for obtaining the volatile organic compound (VOC) distribution in the vertical direction of the soil by the soil gas analysis method according to claim 12. Method for soil gas analysis.