A plant uptake barrier for field use for different forms of semi-volatile organic contaminants and method of use

Abstract

The application discloses a plant absorption and isolation device for different forms of semi-volatile organic pollutants in the wild and a use method thereof. Air inlet and outlet cylinders are respectively arranged at air inlet and outlet holes at different heights, and self-ventilation is realized by using a chimney effect; the air inlet and outlet holes are provided with solar fans to assist the device in ventilation and air exchange. By arranging a stainless steel screen on the air inlet and outlet cylinders, particulate pollutants in the inlet air are filtered, so that the plant only absorbs gaseous pollutants through leaves and absorbs pollutants in soil through roots; by arranging PUF on the air inlet and outlet cylinders, gaseous and particulate pollutants are adsorbed, so that the plant only absorbs pollutants in soil through roots, thereby realizing that the plant absorbs different forms of semi-volatile organic pollutants through different channels. The contribution rate of different absorption channels is calculated by the concentration difference of the plant under different exposures. The device has simple structure, is convenient to disassemble and install, has good light transmittance and strong impact resistance, can realize self-ventilation without power, and overcomes many limitations of field conditions.

Description

Technical Field

[0001] This invention belongs to the field of environmental pollutant monitoring technology, and relates to a plant absorption and isolation device for semi-volatile organic pollutants in different forms in the field and its usage method. Background Technology

[0002] With the increasing impact of human activities, environmental pollution is becoming increasingly serious, especially semi-volatile organic pollutants (SVOCs) which are difficult to degrade and persistent in the environment. Studies have shown that these compounds can persist in the environment, including air, water, and soil, and have carcinogenic, neurotoxic, reproductive, or developmental toxic effects, leading to a series of ecological and environmental problems and human health issues. Plants absorb organic pollutants mainly through two pathways: (1) the soil-root-leaf pathway, i.e., root absorption; and (2) the air-leaf-root pathway, i.e., leaf absorption. The leaf absorption pathway can be further divided into two types: a) absorption by leaves in the form of gaseous pollutants; and b) deposition on leaves or capture by leaves in the form of particulate pollutants (fine particles or dust), which then enter the leaves through diffusion, stomata, or hydathodes. Pollutants absorbed by plants can be transferred through the food chain and ultimately harm human health. Current research focuses on the impact of polluted soil on plant absorption of pollutants, but neglects the impact of air pollution on plants. At the same time, the contribution rate of plants to pollutant absorption through different pathways is still difficult to quantify accurately, making it difficult to reduce the risk of pollutant transfer through the food chain through effective intervention measures.

[0003] Most domestic and international scholars have explored the absorption pathways and accumulation patterns of SVOCs in plants through indoor simulation experiments, but quantitative studies on different absorption pathways and their contribution rates are lacking. While laboratory simulation experiments have the advantage of simplifying complex factors, they cannot fully simulate real-world field environments, leading to significant discrepancies between laboratory and field results and conclusions. Therefore, it is necessary to design a plant-specific exposure device suitable for complex field environments to isolate and differentiate different forms of semi-volatile organic pollutants, thereby quantifying the contribution rates of different forms and sources of pollutants to the pollution load within plants. This will provide a theoretical basis for further precise pollution control or remediation. Summary of the Invention

[0004] The purpose of this invention is to provide an isolation device and its usage method suitable for plant absorption research in complex and variable field environments. This device assesses the contribution of different forms of semi-volatile organic pollutants to plant contamination, filling gaps in existing technologies and theories. By installing different filter and adsorbent materials at the device's inlet and outlet, particulate or gaseous pollutants are isolated, allowing pollutants to be exposed to plants in different forms (gas / particulate) and via different pathways (roots / leaves). The chimney effect created by the height difference between the inlet and outlet, combined with a solar-powered fan, achieves ventilation within the isolation device.

[0005] The technical solution of this invention:

[0006] A plant absorption and isolation device for semi-volatile organic pollutants in different forms in the wild includes a cover plate 1, a silicone gasket 1-1, a transparent chamber 2, an air inlet 2-1, an air outlet 2-2, a support strip 2-3, a fixing strip 2-4, a silicone gasket 2-5, a base plate 3, a film 3-1, an elastic cord 3-2, a stainless steel support frame 4, an air inlet cylinder 5, a drain hole 5-1, an air outlet cylinder 6, a solar fan 7, a metal bracket 7-1, passive air sampling material 8, a metal hook 9, a stainless steel screen 10, and polyurethane foam (PUF) 11;

[0007] The cover plate 1 is made of polymethyl methacrylate and tightly covers the upper end of the transparent chamber 2. A silicone gasket 1-1 is installed between the cover plate 1 and the transparent chamber 2 to ensure the airtightness of the transparent chamber 2. The cover plate 1 is detachable to facilitate the collection and analysis of plant samples. The cover plate 1 is tilted at a 45° angle to the horizontal direction, which allows the condensate from plant transpiration to flow down the cover plate 1, preventing it from affecting light and plant growth.

[0008] The transparent chamber 2 is trapezoidal (the size can be adjusted according to the plants) and is made of polymethyl methacrylate. The upper opening is inclined at a 45° angle to the horizontal direction and is sealed by the cover plate 1. The lower end is tightly connected to the base plate 3. Fixing strips 2-4 are installed at the four corners of the lower end of the transparent chamber 2 for installing stainless steel support frames 4. Air inlets 2-1 and air outlets 2-2 are opened on the two opposite sides of the transparent chamber 2 for ventilation.

[0009] The base plate 3 is made of polymethyl methacrylate and is tightly installed below the support strip 2-3 by a stainless steel support frame 4, fixing strip 2-4 and silicone gasket 2-5 to ensure the airtightness of the device; the film 3-1 is installed in the middle hole of the base plate 3; the annular elastic line 3-2 is installed in the middle of the film 3-1, and the above-ground part of the plant enters the transparent chamber 2 through the hole of the elastic line 3-2 on the film. The elastic line can ensure the airtightness of the transparent chamber 2 after it contracts.

[0010] Both the air inlet 2-1 and the air outlet 2-2 are circular and are located on opposite sides of the transparent chamber 2. The air inlet 2-1 is located below the device, and the air outlet 2-2 is located above the device. The height difference between the two must be greater than 50cm in order to create a "chimney effect" and enhance the ventilation of the transparent chamber 2.

[0011] Both the air inlet 5 and the air outlet 6 are made of polymethyl methacrylate and are installed at the air inlet 2-1 and the air outlet 2-2 respectively. Stainless steel screens 10 or PUF11 can be installed on the air inlet 5 and the air outlet 6 to isolate particulate or gaseous SVOCs.

[0012] Stainless steel mesh 10 is installed inside the air inlet cylinder 5 and the air outlet cylinder 6 to isolate particulate SVOCs; PUF11 is polyurethane foam, installed inside the air inlet cylinder 5 and the air outlet cylinder 6 to isolate both gaseous and particulate SVOCs.

[0013] Drainage hole 5-1 is located below air inlet 5 and air outlet 6 to drain rainwater in a timely manner and prevent rainwater from wetting PUF11;

[0014] The solar fan 7 is mounted on the outside of the air inlet 5 and the air outlet 6 via a metal bracket 7-1 to enhance the ventilation efficiency of the transparent chamber 2.

[0015] Passive air sampling material 8 is used to detect the concentration of SVOCs and ventilation effect in the transparent chamber 2. It can be (but is not limited to) polydimethylsiloxane (PDMS) sampling strips, which are suspended on metal hooks 9 and placed at the vertical line of the transparent chamber 2. The metal hooks 9 are connected and fixed to the drain hole 5-1 of the air outlet 6.

[0016] A method for using a plant-based absorption and isolation device for different forms of semi-volatile organic pollutants in the wild includes the following steps:

[0017] Step 1: Before sampling, the passive air sampling material 8 and PUF11 are subjected to Soxhlet extraction with acetone and dichloromethane in sequence. The passive air sampling material 8 can be (but is not limited to) polydimethylsiloxane sheets, and PUF11 is (but is not limited to) polyurethane foam that can adsorb gaseous and particulate pollutants.

[0018] Step 2: After cleaning, PUF11 is vacuum dried to remove residual solvent, wrapped in aluminum foil, sealed in an airtight bag, and stored in a -20°C refrigerator until the test.

[0019] Step 3: Immerse the passive air sampling material 8 in a methanol:water (v / v, 1:1) solution with a passive sampling performance reference (which may be an isotopically labeled target compound) added, and shake the sample on a shaker to load the sampling performance reference to examine the passive air sampling rate and the ventilation of the device.

[0020] Step 4: Assemble the plant isolation device at the sampling site, insert the stainless steel support frame 4 below the ground, and cover the plant under test with the device through the ring elastic line 3-2 to conduct an exposure test (the exposure period can be determined according to the plant growth cycle).

[0021] Step 5: After the experiment, the passive air sampling material 8 and plant samples from different isolation devices are recovered for subsequent analysis, testing and calculation to obtain the contribution rate of plants to the absorption of different forms of SVOCs through different pathways.

[0022] The beneficial effects of this invention are:

[0023] 1) The material used in this invention is polymethyl methacrylate, which has a much higher light transmittance and impact resistance than glass. It is suitable for complex and ever-changing outdoor environmental conditions and can ensure the light required for the normal growth of plants.

[0024] 2) A plant absorption and isolation device for semi-volatile organic pollutants in different forms in the field. It mainly utilizes the "chimney effect" caused by the height difference between the air inlet and outlet and the temperature difference inside the device to achieve ventilation of the device, overcoming the limitations of no electricity and difficult ventilation in field experiments.

[0025] 3) Small fans powered by solar energy were installed at the air inlet and outlet to assist ventilation, which further overcame the problems of lack of electricity and difficulty in ventilation in field experiments, and reduced the impact on plant growth.

[0026] 4) This invention, by installing isolation and adsorption materials with different properties at the air inlet and outlet, can isolate particulate or gaseous SVOCs, enabling plant exposure to different forms of SVOCs in the field. This fills the technological gap in assessing the contribution rate of plants to the absorption of different forms of SVOCs through different pathways under field conditions. The calculation results can guide agricultural production and precise prevention and control of agricultural product pollution.

[0027] 5) The isolation device of the present invention has a simple structure, is easy to carry, easy to install, easy to operate, requires no power supply, and is inexpensive and saves expenses.

[0028] 6) The size of the isolation device can be flexibly set according to the plant species, and appropriate materials for blocking gaseous or particulate pollutants (not limited to screens and polyurethane foam) can be selected.

[0029] In summary, this isolation device is suitable for complex field environments and effectively isolates semi-volatile organic pollutants in different forms. Through its application, the contribution of pollutants of different forms and sources to the pollution load within plants can be quantitatively analyzed, providing a more precise theoretical basis and practical guidance for pollution control. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the structure of a plant absorption and isolation device for semi-volatile organic pollutants in different forms in the field, as described in this invention.

[0031] Figure 2 This is a three-dimensional schematic diagram of a plant absorption and isolation device for semi-volatile organic pollutants in different forms in the field, as described in this invention.

[0032] Figure 3 (a) is a schematic diagram of the air inlet cylinder structure for installing the screen according to the present invention;

[0033] Figure 3(b) is a schematic diagram of the air outlet structure for installing the screen according to the present invention;

[0034] Figure 4 (a) is a schematic diagram of the air intake structure with PUF installed according to the present invention;

[0035] Figure 4 (b) is a schematic diagram of the air outlet structure for installing the PUF according to the present invention;

[0036] Figure 5 This is a partially enlarged schematic diagram of the bottom structure of the device of the present invention;

[0037] Figure 6 A comparison chart of PAH concentrations in the air within isolation devices using different adsorption materials;

[0038] Figure 7 The contribution rate of different PAH morphologies to plant leaves was calculated using the isolation device.

[0039] In the diagram: 1. Cover plate, 1-1. Silicone gasket, 2. Transparent chamber, 2-1. Air inlet, 2-2. Air outlet, 2-3. Support strip, 2-4. Fixing strip, 2-5. Silicone gasket, 3. Base plate, 3-1. Membrane, 3-2. Elastic line, 4. Stainless steel support frame, 4-1. Fixing groove, 5. Air inlet, 5-1. Drain hole, 6. Air outlet, 7. Solar fan, 7-1. Metal bracket, 8. Passive air sampling material, 9. Metal hook, 10. Stainless steel screen, 11. Polyurethane foam (PUF). Detailed Implementation

[0040] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings and technical solutions.

[0041] like Figures 1 to 5As shown, the present invention provides a plant absorption and isolation device for semi-volatile organic pollutants in different forms in the field, including a cover plate 1, a gasket 1-1, a transparent chamber 2, an air inlet 2-1, an air outlet 2-2, a support strip 2-3, a fixing strip 2-4, a silicone gasket 2-5, a base plate 3, a film 3-1, an elastic cord 3-2, a stainless steel support frame 4, an air inlet cylinder 5, a drain hole 5-1, an air outlet cylinder 6, a solar fan 7, a passive air sampling material 8, a metal hook 9, a stainless steel screen 10, and a PUF 11. The transparent chamber 2 measures 30×25×90 (lower) cm and 110 (higher) cm. Air inlet 2-1 and air outlet 2-2 are located on the front and rear walls of the transparent chamber 2, 15 cm from the bottom and 10 cm from the top, respectively, both with a diameter of 8 cm. Air inlet cylinder 5 and air outlet cylinder 6, both with an outer diameter of 8 cm, are installed at air inlet 2-1 and air outlet 2-2, respectively. A solar fan 7 is mounted on both sides of air inlet cylinder 5 and air outlet cylinder 6 via a metal frame 7-1. A drain hole 5-1 is located in the center of the side walls of air inlet cylinder 5 and air outlet cylinder 6. The passive air sampling material 8 is polydimethylsiloxane, measuring 5×5 cm, and is effective against semi-volatile organic pollutants. The dye has good adsorption properties and is connected to the drain hole 5-1 of the air outlet 6 via a metal hook 9, and is suspended in the middle of the device; the support strip 2-3 is located 10cm from the bottom of the transparent chamber 2 and is attached with a silicone gasket 2-5; the bottom plate 3 has a 10cm diameter hole in the middle and is fitted with a telescopic film 3-1 and a ring elastic line 3-2, which can ensure that the plant can pass through and fit tightly against the plant stem, sealing it and not affecting the normal growth of the plant; the support frame 4 is tapered at the bottom and has a fixing groove 4-1 engraved at the top, and is installed on the fixing strip 2-4 at the four corners of the transparent chamber 2, which can be used to fix the device to the ground and ensure that the bottom plate 3 and the gasket 2-5 fit tightly.

[0042] Prepare three sets of the above-described apparatus for use together. The apparatus is consistent with the description above, such as... Figure 2 As shown, the above-ground parts of the dryland rice pass through the annular elastic line 3-2 into device one. SVOCs in the plant leaves come from air, particles, and root absorption. Device two, based on device one, replaces the air inlet 5 and air outlet 6 with air inlet 5 and air outlet 6 equipped with stainless steel screens 10, as shown. Figure 3 As shown, the stainless steel screen 10 blocks the entry of particulate matter, while SVOCs in plant leaves come from air and root absorption; Device 3, based on Device 1, replaces the air inlet cylinder 5 and air outlet cylinder 6 with air inlet cylinder 5 and air outlet cylinder 6 equipped with PUF11 (diameter 8.2cm, height 2.5cm), as shown. Figure 4 As shown, PUF11 blocks the entry of particulate matter and airborne SVOCs, and SVOCs in plant leaves are absorbed only from the roots.

[0043] The method of using the plant absorption and isolation device for different forms of semi-volatile organic pollutants in the field as described in this invention includes the following steps:

[0044] Before sampling, wipe the cover plate 1, transparent chamber 2, bottom plate 3, air inlet 5 and air outlet 6, metal hook 9, stainless steel screen 10, etc. thoroughly with detergent, then rinse them with running tap water, rinse them three times with ultrapure water, and let them air dry to ensure the cleanliness of the device.

[0045] Before sampling, passive air sampling materials 8 and PUF11 were successively extracted with acetone and dichloromethane for 72 hours to purify the sampling materials and remove background values. After extraction, PUF11 was placed in a vacuum desiccator for vacuum drying, and finally wrapped in aluminum foil, placed in a sealed bag and stored at -20°C. Passive air sampling material 8 was shaken and soaked in a methanol:water (v / v, 1:1) solution with added sampling performance reference material for 5 days to load the performance reference material.

[0046] Before sampling begins, the three isolation devices mentioned above are set up as follows: Figure 2 Assemble the part above base plate 3, and install the air inlet cylinder 5 and air outlet cylinder 6 of devices two and three. Figure 4 and Figure 5 Assembly method: First, pass the three base plates 3 through the ring elastic wires 3-2 and place them on the above-ground stems of the three plants. Then, cover them with the isolation device, install the support frame 4, and insert it into the ground until the four corners of the transparent chamber 2 touch the ground. The sampling period is 20 days.

[0047] After sampling, open cover 1, use tweezers to remove the passive air sampling material 8 from the three barrier devices, wrap it in aluminum foil, put it in a sealed bag, and store it in a -20℃ freezer. At the same time, collect plant tissue samples from the three barrier devices, put them in sealed bags, and store them in a -20℃ freezer.

[0048] Passive air sampling material 8 was extracted with ethyl acetate by shaking for 24 h. Plant leaf samples were extracted with an acetone:dichloromethane (1:1, v / v) mixture by ultrasonic extraction. After nitrogen blowing, the extract was purified by passing it through a silica gel column filled with anhydrous sodium sulfate and 3% deactivated silica gel from top to bottom. Eluent was used for elution, and the eluent was collected, concentrated by nitrogen blowing, and an internal standard was added. The results were then analyzed by gas chromatography-mass spectrometry.

[0049] Quantification was performed using the internal standard method based on the peak area of ​​the characteristic ions of the target semi-volatile organic pollutant.

[0050] The contribution rate of different absorption pathways in plants can be calculated using the following formula:

[0051]

[0052]

[0053]

[0054] The following specific embodiment of the present invention will be used to verify the beneficial effects of the plant absorption and isolation device for different forms of semi-volatile organic pollutants in the field in practical applications.

[0055] The experiment was conducted in a dry rice paddy in Zhuanghe City, Dalian, Liaoning Province.

[0056] Three clumps of upland rice of uniform height and growth were selected from the paddy field and covered with plant absorption and isolation devices for different forms of semi-volatile organic pollutants in the wild (device one had no treatment in its inlet and outlet air cylinders; device two had screens installed in its inlet and outlet air cylinders; device three had PUF installed in its inlet and outlet air cylinders). After 20 days of sampling, the devices were retrieved, passive air sampling material 8 was collected, and tissue samples such as upland rice leaves were collected.

[0057] This experiment measured the air concentration of PAHs monomers in three isolation devices and found a clear concentration gradient of PAHs in the air of different isolation devices, namely, Device 1 > Device 2 > Device 3. Figure 6 As shown.

[0058] The contribution rates of different absorption pathways in upland rice to PAH accumulation in upland rice leaves were calculated using the above formulas, such as... Figure 7 As shown.

Claims

1. A method for using a plant absorption and isolation device for different forms of semi-volatile organic pollutants in the wild, characterized in that, The plant absorption isolation device includes a cover plate (1), a first silicone pad (1-1), a transparent chamber (2), an air inlet (2-1), an air outlet (2-2), a support strip (2-3), a fixing strip (2-4), a second silicone pad (2-5), a base plate (3), a film (3-1), an elastic cord (3-2), a stainless steel support frame (4), an air inlet cylinder (5), a drain hole (5-1), an air outlet cylinder (6), a solar fan (7), a metal bracket (7-1), passive air sampling material (8), and a metal hook (9). The cover plate (1) is tightly covered on the upper end of the transparent chamber (2), and a first silicone gasket (1-1) is installed between the cover plate (1) and the transparent chamber (2) to ensure the airtightness of the transparent chamber (2); the cover plate (1) is inclined at a 45° angle to the horizontal direction; The transparent chamber (2) is trapezoidal, with the upper opening at a 45° angle to the horizontal direction and sealed by a cover plate (1); the lower end is tightly connected to the base plate (3), and fixing strips (2-4) are installed at the four corners of the lower end of the transparent chamber (2) for installing stainless steel support frames (4). Air inlets (2-1) and air outlets (2-2) are opened on the two opposite sides of the transparent chamber (2) for ventilation of the transparent chamber (2); The base plate (3) is tightly installed below the support strip (2-3) by a stainless steel support frame (4), a fixing strip (2-4), and a second silicone gasket (2-5) to ensure the airtightness of the device; the film (3-1) is installed in the middle hole of the base plate (3); the annular elastic line (3-2) is installed in the middle of the film (3-1), and the above-ground part of the plant enters the transparent chamber (2) through the hole of the elastic line (3-2) on the film. After the elastic line shrinks, it can ensure the airtightness of the transparent chamber (2); Both the air inlet (2-1) and the air outlet (2-2) are circular and are located on opposite sides of the transparent chamber (2). The air inlet (2-1) is located at the bottom of the device, and the air outlet (2-2) is located at the top of the device. The air inlet (5) and air outlet (6) are installed at the air inlet (2-1) and air outlet (2-2) respectively; stainless steel screens (10) or PUF (11) are installed on the inner side of the air inlet (5) and air outlet (6) to isolate particulate or gaseous SVOCs. The drain hole (5-1) is located below the air inlet (5) and the air outlet (6) to drain rainwater in a timely manner; The solar fan (7) is mounted on the outside of the air inlet (5) and air outlet (6) via a metal bracket (7-1) to enhance the ventilation efficiency of the transparent chamber (2); Passive air sampling material (8) is used to detect the concentration of SVOCs and ventilation effect in the transparent chamber (2). It is suspended on a metal hook (9) and placed at the vertical line of the transparent chamber (2). The metal hook (9) is connected and fixed to the drain hole (5-1) of the air outlet (6). The height difference between the air inlet (2-1) and the air outlet (2-2) must be >50cm in order to form a "chimney effect" and enhance the ventilation of the transparent chamber (2); Prepare three sets of the above-mentioned plant absorption isolation devices for use in combination; the first set of plant absorption isolation devices: the above-ground part of the dry rice passes through the ring elastic line (3-2) and enters the first set of plant absorption isolation devices. The SVOCs in the plant leaves come from the air, particles and roots; the second set of plant absorption isolation devices is based on the first set of plant absorption isolation devices, replacing the air inlet (5) and air outlet (6) with air inlet (5) and air outlet (6) with stainless steel screen (10). The stainless steel screen (10) blocks the entry of particles. The SVOCs in the plant leaves come from the air and roots; the third set of plant absorption isolation devices is based on the second set of plant absorption isolation devices, replacing the air inlet (5) and air outlet (6) with air inlet (5) and air outlet (6) with PUF (11). The PUF (11) blocks the entry of particles and SVOCs in the air. The SVOCs in the plant leaves come only from the roots. Includes the following steps: Step 1: Before sampling, the passive air sampling material (8) and PUF (11) were subjected to Soxhlet extraction with acetone and dichloromethane in sequence. Step 2: After cleaning, the PUF (11) is vacuum dried to remove residual solvent, wrapped in aluminum foil, sealed in a tight bag, and stored in a -20°C refrigerator until the test. Step 3: Immerse the passive air sampling material (8) in a mixed solution of methanol and water with a volume ratio of 1:1 for adding passive sampling performance reference material, and shake the sampled performance reference material on a shaker to examine the passive air sampling rate and the ventilation of the device. Step 4: Assemble the plant absorption isolation device at the sampling site, insert the stainless steel support frame (4) below the ground, and cover the plant under test with the plant absorption isolation device through the ring elastic line (3-2) to conduct an exposure test; Step 5: After the experiment, the passive air sampling material (8) and the plant samples in the plant absorption isolation device are recovered for subsequent analysis, testing and calculation to obtain the contribution rate of plants to absorb different forms of SVOCs through different pathways.

2. The method of use according to claim 1, characterized in that, The cover plate (1) is detachable, which facilitates the collection and analysis of plant samples.

3. The method of use according to claim 1, characterized in that, The passive air sampling material (8) is a polydimethylsiloxane sampling strip.

4. The method of use according to claim 1, characterized in that, The cover plate (1), transparent chamber (2), bottom plate (3), air inlet (5) and air outlet (6) are all made of polymethyl methacrylate.

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