Apparatus and method for in-situ inducing and quantifying organic carbon priming effect in different soil layers

Abstract

The application discloses a device for in-situ inducing and quantifying the organic carbon priming effect of different soil layers, comprising a test cylinder, a plurality of gas wells, a plurality of infusion members and a gas pipe; the plurality of gas wells are arranged at different height positions in the test cylinder in correspondence, each gas well comprises a gas extraction hole and an air inlet hole, the air inlet hole is provided with a filter assembly, and the gas extraction hole is arranged on the side of the gas well close to the bottom position; the plurality of infusion members are arranged on the circumferential side of the gas well at each height position in correspondence, one end of each infusion member is vertically embedded in the soil, and the other end of each infusion member extends out of the soil to above the soil surface and is connected with a liquid supply assembly; one end of the gas pipe is connected with the gas extraction hole, and the other end of the gas pipe is connected with a gas extraction member. 13 By adding C-labeled exogenous glucose solution to different depths of soil, periodically extracting greenhouse gases discharged from corresponding soil layers, and monitoring the priming effect of surface and deep soil organic carbon decomposition, the differences in greenhouse gas emission between different depths of soil and the change law of the regulation factors are determined.

Description

Technical Field

[0001] This invention relates to the field of soil testing equipment technology, specifically to a device and method for in-situ induction and quantification of the organic carbon activation effect in different soil layers. Background Technology

[0002] Soil carbon pools are the largest carbon pools in terrestrial ecosystems and are crucial participants in the global carbon cycle. They store 2-3 times the carbon content of plant and atmospheric carbon pools combined, and release 8-10 times the amount of carbon into the atmosphere annually, equivalent to fossil fuel emissions. Therefore, even small changes in soil organic carbon pools can lead to variations in atmospheric CO2 concentration, thus impacting the carbon cycle and climate change. In forest ecosystems, soil is a vast carbon pool; the carbon storage in deeper soil layers is 1.24 times that of the surface layer. Therefore, enhancing the carbon sequestration capacity of deeper soils and reducing carbon emissions is a vital pathway to mitigating the increase in atmospheric CO2 concentration.

[0003] However, how deep soil greenhouse gas emissions will respond to global warming remains highly uncertain. Furthermore, traditional methods for studying deep soils—namely, collecting soil samples and bringing them back to a controlled laboratory for cultivation—significantly alter the microenvironment and structural state of the deep soils, affecting the accuracy and reliability of the research results.

[0004] The phenomenon where the input of exogenous organic matter alters the decomposition rate of native soil organic matter is known as the activating effect. The activating effect is a common phenomenon in soil, primarily caused by the input of exogenous carbon and rhizosphere exudates, and it influences soil carbon storage by affecting the decomposition of soil organic matter. However, existing experimental procedures for inducing and quantifying the activating effect, such as the soil culture device and method for detecting organic matter mineralization and the activating effect described in application number CN112834302A, require bringing soil samples back to the laboratory for testing. This not only makes it difficult to maintain the microenvironment and structural state of deep soil layers, affecting the accuracy and reliability of the research results, but also limits each test to a single soil layer, making it difficult to directly understand the differences in greenhouse gas release across different soil layers. Summary of the Invention

[0005] The purpose of this invention is to provide a device for in-situ induction and quantification of the organic carbon activation effect in different soil layers. This device solves the technical limitation of difficulty in in-situ induction and accurate quantification of the soil organic matter decomposition activation effect in the field, and overcomes the disturbance to soil structure and changes in the external environment caused by indoor cultivation experiments.

[0006] The technical solution of this invention is:

[0007] A device for in-situ induction and quantification of the organic carbon activation effect in different soil layers includes: a test cylinder, bottomless and coverless, vertically buried in the test soil; multiple gas wells, correspondingly arranged at different heights within the test cylinder, each gas well having a cavity, each gas well including: an extraction port and an inlet port, the inlet port having a filter assembly for preventing soil and liquid from entering the gas well and allowing gas to enter the cavity of the gas well through the filter assembly, the extraction port being located on the side of the gas well near the bottom; multiple infusion devices, correspondingly arranged around the gas well at each height, one end of each infusion device being vertically buried in the soil, the other end being connected to a liquid supply assembly, and the other end extending from the soil to above the soil surface, the liquid supply assembly injecting exogenous glucose solution into the periphery of the gas wells in different soil layers through the infusion devices; a gas pipe, one end connected to the extraction port, the other end extending from the soil to above the soil surface and sealed by a sealing element, the sealing element being removed to allow the gas pipe to connect to the extraction device, and to extract gas from the cavity of the gas well.

[0008] Furthermore, the sealing element is a sealing nut.

[0009] Furthermore, the gas well is vertically positioned in the soil.

[0010] Furthermore, the infusion device includes: a main tube, vertically buried in the soil, with a multi-port tube connected to one end buried in the soil; multiple arc-shaped tubes, one end of which is connected to the channel of the multi-port tube; and multiple branch tubes, arranged vertically in a ring array around the gas well, with one end of each branch tube connected to the other end of the arc-shaped tube.

[0011] Furthermore, the other end of the main tube is connected to the liquid supply assembly via a peristaltic pump.

[0012] Furthermore, the other end of each of the branch conduits is closed, a through hole is opened on the body of each of the branch conduits, and a layer of nylon mesh is wrapped around the section of each of the branch conduits with the through hole.

[0013] Furthermore, there are two air inlets, which are symmetrically arranged on both sides of the gas well at the waist position, and each gas well is equipped with a filter assembly.

[0014] Furthermore, the filter assembly includes: a threaded tube, one end of which is inserted into the air inlet, and the middle section is sealed to the air inlet; the threaded tube has threads at the end located outside the gas well; a gasket with a through hole; a breathable and waterproof membrane covering the gasket to seal the hole; and a fixing cap with a hole on its surface, the gasket being fitted into the fixing cap, the fixing cap being threaded to the threaded end of the threaded tube, and after tightening the fixing cap, the breathable and waterproof membrane on the gasket seals the opening of the threaded tube, and the gasket cannot be removed from the hole on the surface of the fixing cap.

[0015] Furthermore, the gas pipes connected to each of the gas wells are of different colors.

[0016] The method for detecting greenhouse gas emissions from deep soil using the above-mentioned device includes the following steps:

[0017] A pit large enough to accommodate the test tube is dug in the soil to be tested. The test tube is placed in the pit, and gas wells are buried at different soil depths, with the gas pipes connected to the extraction holes of each gas well extending above the soil surface. Liquid delivery devices are buried around the gas wells at each depth. After the soil is filled in, exogenous glucose solutions of different concentrations are added to the soil at different depths in the test tube through the liquid delivery devices. After adding the exogenous glucose solutions, gas is periodically extracted through the end of the gas pipe extending above the soil surface for measurement, so as to intuitively understand the differences in greenhouse gas release in each soil layer.

[0018] Compared with the prior art, the beneficial effects of the present invention are:

[0019] 1. This invention solves the technical limitation of being unable to accurately quantify the induction of soil organic matter decomposition in situ in the field, overcomes the disturbance to soil structure and changes in the external environment caused by indoor cultivation experiments, and by accurately adding exogenous glucose solution to soil at different depths and periodically extracting greenhouse gas emissions from the corresponding soil layers, while monitoring the induction effect of organic carbon decomposition in surface and deep soils, it clarifies the differences between soil layers at different depths and the changing patterns of factors regulating greenhouse gas emissions.

[0020] 2. The present invention has a simple overall structure, low cost, simple material sourcing, manufacturing and operation, and convenient sample collection. It can better study the impact of in-situ addition of exogenous carbon on soil carbon dynamics at different depths, and provide accurate data for better predicting the impact of global change on greenhouse gas emissions from future soil ecosystems. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the main structure of the present invention;

[0022] Figure 2 This is a schematic diagram of the gas well structure of the present invention;

[0023] Figure 3 This is a schematic diagram of the structure of the infusion device of the present invention;

[0024] Figure 4 This is a schematic diagram of the filter component structure of the present invention.

[0025] Among them, 1. Test cylinder, 2. Gas well, 21. Filter assembly, 211. Threaded pipe, 212. Gasket, 2121. Hole, 2122. Breathable and waterproof membrane, 213. Fixing cover, 22. Air extraction hole, 23. Air inlet hole, 3. Gas pipe, 31. Seal, 4. Infusion assembly, 41. Main pipe, 411. Multi-port pipe, 42. Branch pipe, 43. Branch pipe, 431. Nylon mesh, 44. Peristaltic pump, 45. Liquid supply assembly. Detailed Implementation

[0026] The following is in conjunction with the appendix Figure 1-4 The specific embodiments of the present invention will be described in detail below. In the description of the present invention, it should be understood that the terms "center," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are only for the convenience of describing the present invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0027] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature; in the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0028] It should be noted that the circuit connections involved in this invention all adopt conventional circuit connection methods and do not involve any innovation.

[0029] Example

[0030] like Figure 1As shown, a device for in-situ induction and quantification of the organic carbon activation effect in different soil layers includes: a test cylinder 1, multiple gas wells 2, multiple infusion fittings 4, and gas pipes 3. The test cylinder 1 is a bottomless and capless stainless steel column, 80 cm high and 40 cm in radius. In use, a pit is dug at the test soil location, and the test cylinder 1 is vertically inserted into the test soil. The multiple gas wells 2 are correspondingly located at different heights within the test cylinder 1, and the multiple gas wells 2 are located on the vertical central axis of the test cylinder 1. Figure 2 As shown, each gas well 2 is a tank with an internal cavity. The outer diameter of the gas well is 11 cm and the height is 18 cm. Each gas well 2 includes an extraction port 22 and an inlet port 23. The inlet port 23 is equipped with a filter assembly 21 to prevent soil and liquid from entering the gas well 2, and to allow greenhouse gases emitted from the soil layer to enter the cavity of the gas well 2 through the filter assembly 21. The extraction port 22 is located on the side of the gas well 2 near the bottom. Multiple liquid delivery components 4 are correspondingly arranged around the gas well 2 at each height position. One end of the liquid delivery component 4 is vertically buried in the soil, and the other end is connected to the liquid supply component 45. The other end extends from the soil to above the soil surface. The liquid supply component injects liquid into the gas well 2 around different soil layers through the liquid delivery components 4. 13 C-labeled glucose solution; one end of gas tube 3 is connected to the vent 22, and the other end extends from the soil to above the soil surface and is sealed by sealing member 31. Remove sealing member 31 to connect gas tube 3 to venting member. Sealing member 31 is selected as sealing nut. Gas is extracted from the cavity of gas well 2. Venting member can be selected as venting injector. Greenhouse gas in the cavity of gas well 2 is periodically extracted by venting injector.

[0031] The method for detecting greenhouse gas emissions from deep soil using the above-mentioned device includes the following steps:

[0032] Dig a pit large enough to accommodate the test cylinder 1 at the soil site to be tested. For example, dig a pit 80cm high and 50cm in diameter at the soil site to be tested. Then place the test cylinder 1 into the pit. Place a gas well 2 at the center of the test cylinder 1, and set its corresponding gas pipe 3 and infusion device 4 in the positions described above. Then fill the pit with 20cm of soil, and bury the next gas well 2 and its corresponding gas pipe 3 and infusion device 4. Continue in this manner, burying the next gas well 2 after each 20cm layer of soil, ensuring that the gas pipe 3 connected to the extraction port 22 of each gas well 2 can extend out of the soil. Above the surface, one end of the infusion unit 4 can extend out of the soil surface and connect the infusion unit to the liquid supply component. The gas pipes 3 connected to each gas well 2 are numbered to facilitate subsequent gas extraction and testing. After the soil in the test cylinder 1 is filled, exogenous glucose solution is added to different depth layers in the soil in the test cylinder 1 through the infusion unit 4. Under the premise of the same input solution volume, the proportion of glucose added to SOC (which varies in different soil layers) is consistent. After adding exogenous glucose solution, gas is extracted periodically through the end of the gas pipe 3 that extends out of the soil surface for measurement, so as to intuitively understand the differences in greenhouse gas release in each soil layer.

[0033] To avoid excessive disturbance to the soil structure, the soil is layered in 20cm increments during digging, and then backfilled sequentially to minimize disturbance.

[0034] Preferred, such as Figure 1 As shown, gas wells 2 are placed vertically in soil layers at different depths inside the test cylinder 1, and multiple gas wells 2 are located on the vertical center line of the test cylinder 1, which helps to form a greenhouse gas environment with uniform concentration inside the soil and gas wells 2 during gas extraction.

[0035] Preferred, such as Figure 1 and Figure 3 As shown, in order to ensure that each infusion unit 4 can uniformly inject the solution into the soil surrounding the gas well 2, the infusion unit 4 includes: a main pipe 41, multiple arc-shaped pipes 42, and multiple branch pipes 43. The main pipe 41 is vertically buried in the soil, and one end buried in the soil is connected to a multi-port pipe 411. The multi-port pipe 411 is generally located above the gas well 2, on the extension line of the vertical central axis of the gas well. The other end of the main pipe 41 is connected to the liquid supply component 45. One end of the multiple arc-shaped pipes 42 is connected to the channel of the multi-port pipe 411. The multiple branch pipes 43 are arranged vertically in a ring array with the gas well 2 as the center, and one end of each branch pipe 43 is connected to the other end of the arc-shaped pipe 42.

[0036] Preferably, in order to accurately control the dosage and concentration of the infusion and ensure that the glucose addition is consistent in proportion to SOC (which varies in different soil layers) under the premise of the same infusion volume, the other end of the main pipe 41 is connected to the infusion supply assembly 45 through a peristaltic pump 44.

[0037] Preferably, in order to further improve the uniform penetration of the introduced solution into the soil layer, such as... Figure 3 As shown, the other end of each branch conduit 43 is closed, and through holes are opened on the body of each branch conduit 43 to allow the solution to begin to permeate from different height positions. Moreover, a layer of nylon mesh 431 is wrapped around the section of each branch conduit 43 with through holes to prevent soil from clogging the through holes.

[0038] Preferred, such as Figure 2 As shown, in order to facilitate the entry of greenhouse gases in the soil into the cavity of gas well 2, there are two air inlets 23. The two air inlets 23 are symmetrically arranged on both sides of the waist position of gas well 2, that is, on both sides near the middle position. Each gas well 2 is equipped with a filter component.

[0039] Preferably, in order to improve the blocking effect of the filter component 31 on soil and liquid, such as Figure 4 As shown, the filter assembly 21 includes: a threaded tube 211, a gasket 212, and a fixing cap 213. One end of the threaded tube 211 is inserted into the air inlet 23 and extends into the cavity of the gas well 2. The middle section of the threaded tube 211 and the air inlet 23 are sealed. The end of the threaded tube 211 located outside the gas well 2 has threads. The gasket 212 has a through hole 2121. A breathable and waterproof membrane 2122 covers the gasket 212 to seal the hole 2121. The breathable and waterproof membrane 2122 allows gas to pass through. However, it cannot pass through liquids and soil; a hole is made on the cover surface of the fixing cover 213, the size of the hole is smaller than the size of the gasket 212, so that the gasket 212 cannot be removed from the hole on the cover surface of the fixing cover 213. During installation, the gasket 212 is fitted into the fixing cover 213, and the fixing cover 213 is threadedly connected to the threaded end of the threaded pipe 211. After the fixing cover 213 is tightened continuously, the gasket 212 gets closer and closer to the opening of the threaded pipe 211 until the breathable and waterproof membrane 2122 on the gasket 212 is sealed to the opening of the threaded pipe 211.

[0040] Preferably, in order to facilitate the differentiation of gas pipes 3 connected to gas wells 2 in different soil layers, and thus accurately extract greenhouse gases from the target gas wells 2, the gas pipes 3 connected to each gas well 2 are of a different color.

[0041] The above-disclosed embodiments are merely preferred embodiments of the present invention. However, the embodiments of the present invention are not limited thereto, and any variations that can be conceived by those skilled in the art should fall within the protection scope of the present invention.

Claims

1. A device for in-situ induction and quantification of the organic carbon activation effect in different soil layers, characterized in that, include: The test tube, without a bottom or cover, is vertically buried in the soil being tested; Multiple gas wells are set at different height positions inside the test cylinder. Each gas well is a tank with an internal cavity. Each gas well includes an air extraction port and an air inlet port. The air inlet port is equipped with a filter assembly to prevent soil and liquid from entering the gas well and to allow gas to enter the cavity of the gas well through the filter assembly. Multiple infusion units are correspondingly installed around the gas well at each height position. One end of each infusion unit is vertically buried in the soil, and the other end extends from the soil to the soil surface and is connected to the liquid supply assembly. The liquid supply assembly injects exogenous glucose solution into the gas well periphery of different soil layers through the infusion units. A gas pipe, one end of which is connected to the air extraction hole, and the other end extends from the soil to above the soil surface and is sealed by a sealing element. The sealing element is removed to allow the gas pipe to connect to the air extraction element and extract the gas from the gas well cavity. The gas well is vertically installed in the soil; The infusion device includes: The main pipe is vertically buried in the soil, and the end buried in the soil is connected to the multi-port pipe. Multiple arc-shaped tubes, one end of which is connected to the channel of the multi-pass tube; Multiple branch pipes are arranged vertically in a circular array around the gas well, with one end of each branch pipe connected to the other end of the arc-shaped pipe. The other end of the main tube is connected to the liquid supply assembly via a peristaltic pump; The other end of each of the branch conduits is closed, and a through hole is opened on the tube body of each of the branch conduits. A layer of nylon mesh is wrapped around the section of each of the branch conduits with the through hole. The filtering component includes: A threaded tube, one end of which is inserted into the air inlet, and the middle section is sealed between the air inlet and the middle section. The threaded tube is threaded at the end located outside the gas well. A gasket, wherein a through hole is formed in the gasket; A breathable and waterproof membrane is provided, which covers the gasket to seal the holes. A fixed cover has a hole on its surface. A gasket is fitted inside the fixed cover. The fixed cover is threaded to the threaded end of the threaded tube. After the fixed cover is tightened, the breathable and waterproof membrane on the gasket seals the opening of the threaded tube, and the gasket cannot come out of the hole on the surface of the fixed cover. The gas pipes connected to each of the gas wells are of a different color.

2. The device for in-situ induction and quantification of the organic carbon activation effect in different soil layers according to claim 1, characterized in that, The sealing element is a sealing nut.

3. The device for in-situ induction and quantification of the organic carbon activation effect in different soil layers according to claim 1, characterized in that, There are two air inlets, which are symmetrically arranged at the waist of the gas well, and the air extraction port is opened on the side of the gas well near the bottom.

4. The method for detecting greenhouse gas emissions from deep soil using the apparatus according to claim 1, characterized in that, Includes the following steps: A pit is dug at the soil to be tested to accommodate the test tube. The test tube is placed in the pit, and gas wells are buried at different soil depths, with the gas pipes connected to the extraction holes of each gas well extending above the soil surface. Liquid delivery devices are buried around the gas wells at each depth. After the soil is filled in, exogenous glucose solutions of different concentrations are added to the soil at different depths inside the test tube through the liquid delivery devices. After adding the exogenous glucose solutions, gas is periodically extracted through the end of the gas pipe extending above the soil surface for measurement, allowing for a direct understanding of the differences in greenhouse gas release in each soil layer.

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