A sea-air interface micro-plastic aerosolization detection system and a detection method

Abstract

The application discloses a sea-air interface micro-plastic aerosolization detection system and a detection method. The first box body is a closed box body. An air inlet and an air outlet are arranged on the top cover of the first box body. An overflow pipe is horizontally arranged on the top of the first box body. A horizontal slit is arranged on the overflow pipe. The inlet of the overflow pipe is connected with seawater through a pump. The air inlet is connected with a clean air source. The air outlet is connected with a low-pressure cascade impactor. A first box body overflow port is arranged at a set height of the first box body. The first box body overflow port is sequentially connected with a multi-stage pre-filter and a polycarbonate membrane-glass sand core filter. Aerosol particles generated by breaking waves are collected into an atmospheric particulate matter grading sampler. Micro-plastic particles in seawater and air are identified and counted through different light excitation channels of a fluorescence microscope. Finally, the aerosolization degree of micro-plastics at the sea-air interface is quantified through a micro-plastic aerosolization formula.

Description

Technical Field

[0001] This invention relates to the field of experimental apparatus technology, and in particular to a detection system and method for detecting the aerosolization of microplastics at the sea-air interface. Background Technology

[0002] The statements herein provide only background information in relation to this invention and do not necessarily constitute prior art.

[0003] Approximately 10 million tons of plastic waste flow into the ocean each year, breaking down into micron- or nano-sized plastic particles through physical, chemical, and biological processes. While the ocean is considered a sink for microplastics, studies have also found microplastic particles in atmospheric particulate matter from distant ocean areas. These microplastic particles may be the result of long-distance atmospheric transport, but ocean surface microplastic particles can also be released into the atmosphere through wave action. Due to their large surface area, microplastics may carry organic matter, viruses, and bacteria from seawater when ejected from the ocean surface, subsequently actively participating in atmospheric chemical processes. Quantifying the degree of microplastic aerosolization at the ocean-atmosphere interface is a crucial step in further accurately estimating the ocean's microplastic emission flux.

[0004] Directly collecting aerosol samples from the ocean to analyze microplastic particles can be affected by many unforeseen environmental factors, and also presents challenges such as long sampling times and complex microplastic sources (including in-situ wave generation and long-distance atmospheric transport). This poses difficulties for in-depth research into the ocean-atmosphere transfer process of microplastic particles. Therefore, creating an artificially controlled environment is necessary. Currently, relatively mature technologies have been developed for artificially simulating wave-breaking processes; however, these methods often utilize the circulation of seawater within a completely closed system to simulate wave-breaking, followed by the collection of aerosol samples for compositional analysis. In actual sampling, the ejection of substances (especially microplastic particles) caused by wave-breaking will continuously reduce the concentration of corresponding components in the seawater, thus affecting the accuracy of the detection. Furthermore, because the pathways of microplastic emissions through wave-breaking have been overlooked, there is still no convenient method or formula to quantify the degree of microplastic aerosolization. This will be crucial data support for clarifying the flux of microplastic emissions from marine sources. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the purpose of this invention is to provide a detection system and method for detecting the aerosolization of microplastics at the sea-air interface.

[0006] To achieve the above objectives, the present invention is implemented through the following technical solution:

[0007] In a first aspect, the present invention provides a detection system for microplastic aerosolization at the sea-air interface. The first chamber is a closed chamber, and an air inlet and an air outlet are provided on the top cover of the first chamber. An overflow pipe is horizontally provided on the top of the first chamber, and a horizontal slit is provided on the overflow pipe. The inlet of the overflow pipe is connected to seawater through a pump. The air inlet is connected to a clean air source, and the air outlet is connected to a low-pressure cascade impactor.

[0008] An overflow port is located at a set height in the first chamber. This overflow port is sequentially connected to a multi-stage pre-filter and a glass frit filter. The glass frit filter uses a polycarbonate track-etched membrane. This membrane has the advantages of regular and uniform pores and good microscopic imaging, making it more suitable for the filtration and counting of microplastics.

[0009] In some embodiments, the overflow pipe includes an inner pipe and an outer pipe arranged coaxially. The inner pipe has a plurality of liquid distribution holes arranged along the axial direction, and the horizontal slit is provided on the outer pipe. These liquid distribution holes are used to ensure uniform water distribution in the outer pipe, reduce turbulent water movement inside the pipe, and thus improve the stability of the water flow at the slit.

[0010] In some embodiments, the distance between the first chamber overflow port and the bottom of the first chamber is greater than the distance between the horizontal slit and the first chamber overflow port. This ensures that the underwater bubble plume process is natural and unaffected by the bottom of the chamber.

[0011] In some embodiments, a second housing is further included, wherein the overflow port of the first housing is connected to the second housing via a bent pipe, the second housing is provided with a second overflow port, and the height of the second overflow port is lower than the height of the first overflow port.

[0012] Preferably, the outlet end of the bent pipe is positioned below the overflow port of the second housing.

[0013] By adopting this setting method, after the liquid level inside the second chamber is kept constant, the outlet end of the bent tube is inserted below the liquid level, which can effectively prevent external particles from entering the headspace of the first chamber through the overflow port of the first chamber, thus avoiding interference from external particles on the aerosol sampling process in the headspace of the first chamber.

[0014] Preferably, the bottom outlet of the second chamber is connected in sequence to a multi-stage pre-filter and a polycarbonate filter membrane-glass core filter.

[0015] In a further preferred embodiment, a pre-filtration collection tank is provided between the multi-stage pre-filter and the polycarbonate filter membrane-glass core filter.

[0016] In some embodiments, the multi-stage filter is a three-stage filter with filtration accuracies of 2 mm, 200 μm and 10 μm respectively.

[0017] Secondly, the present invention provides a method for detecting the aerosolization of microplastics at the ocean-air interface, comprising the following steps:

[0018] Clean air is introduced into the first chamber through the air intake pipe, while seawater, after being coarsely filtered, is continuously pumped into the overflow pipe at the top of the first chamber and forms a water flow at the horizontal slit, which impacts the water surface below, simulating the wave-breaking process and forming aerosols. The aerosols are collected by the low-pressure cascade impactor.

[0019] The seawater overflowing from the first tank undergoes multi-stage pre-filtration, and then uses polycarbonate membranes and glass frit filters to filter out microplastic particles with a diameter of less than 10μm.

[0020] Identification and counting of microplastic particles on polycarbonate films;

[0021] Calculate the degree of aerosolization of microplastic particles.

[0022] In some embodiments, the aerosol formation and collection process maintains a slight positive pressure inside the first chamber. Maintaining a slight positive pressure inside the first chamber not only reduces the airtightness requirements of the system but also effectively prevents external particles from entering the first chamber.

[0023] In some embodiments, different light excitation channels of a fluorescence microscope are used to identify and count microplastic particles on a polycarbonate film.

[0024] In some embodiments, the degree of aerosolization of microplastic particles within a certain particle size range is represented by their aerosolized factor (AF), and the specific formula is as follows:

[0025]

[0026] in, V is the number of microplastic particles within a certain size range on the polycarbonate membrane of a low-pressure cascade impactor. air It is the volume of air collected; V is the number of microplastic particles within a certain size range on the polycarbonate film of a glass frit core. water It is the volume of filtered seawater; and These represent the concentrations of microplastic particles within a specific particle size range in air and water.

[0027] The beneficial effects achieved by one or more embodiments of the present invention described above are as follows:

[0028] A centrifugal pump draws surface seawater into an overflow pipe at the top of the first tank. The seawater overflows through a narrow slit and falls into the water below, simulating a wave-breaking event. An overflow outlet on the right side allows for real-time replenishment of the seawater within the first tank, significantly improving the realism of the experimental results. The overflowing seawater is pre-filtered by a multi-stage particulate filter and then filtered through a polycarbonate membrane to collect microplastic particles. Aerosol particles generated during wave breaking are collected in a graded atmospheric particulate sampler. Microplastic particles in the seawater and air are identified and counted using different light excitation channels of a fluorescence microscope. Finally, the degree of microplastic aerosolization at the sea-air interface is quantified using a microplastic aerosolization formula.

[0029] After the seawater level in the first tank is raised to the overflow port on the right side, the seawater overflows from the first tank and enters the second tank. This ensures that the seawater level in the first tank remains constant and that the seawater in the first tank is updated in real time, so that the sampling process can be as close as possible to the actual field sampling process.

[0030] The second chamber is equipped with a second chamber overflow port. When the seawater level in the second chamber reaches the second chamber overflow port, it can overflow through the second chamber overflow port, reducing the load on the subsequent multi-stage filters and providing a buffer for the subsequent multi-stage filtration of seawater. Attached Figure Description

[0031] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0032] Figure 1 This is a schematic diagram of the overall structure of the air-sea interface microplastic aerosolization detection system according to an embodiment of the present invention;

[0033] Figure 2 This is a schematic diagram of the structure of the first box and the second box in an embodiment of the present invention;

[0034] Figure 3 This is a schematic diagram of the low-pressure cascaded impactor sampler for particulate matter in an embodiment of the present invention;

[0035] Figure 4 This is a schematic diagram of the structure of the microplastic pre-filter in an embodiment of the present invention.

[0036] In the diagram: the spacing or dimensions between parts have been exaggerated to show their positions; the diagram is for illustrative purposes only.

[0037] The components include: 1. Coarse filtration device; 2. Centrifugal pump; 3. First chamber; 3-1. First chamber inlet; 3-2. Overflow pipe; 3-3. First chamber overflow outlet; 3-4. Air inlet; 3-5. Air outlet; 3-6. Pressure reducing pipe; 4. Second chamber; 4-1. Second chamber overflow outlet; 4-2. Second chamber outlet; 5. Low-pressure cascade impactor; 6. Primary pre-filter; 7. Secondary pre-filter; 8. Tertiary pre-filter; 9. Water valve; 10. Diaphragm pump; 11. Pre-filter collection tank. Detailed Implementation

[0038] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0039] The present invention will be further described below with reference to the embodiments.

[0040] like Figure 1 As shown, a microplastic aerosolization detection system at the air-sea interface includes a first chamber 3 and a second chamber 4 located on the right side of the first chamber. An overflow pipe 3-2 with a slit is installed at the top of the first chamber. After seawater is coarsely filtered by the coarse filter 1 (to coarsely filter particles larger than 5mm in the seawater to protect the normal operation of the centrifugal pump 2), the centrifugal pump 2 continuously pumps the seawater into the overflow pipe 3-2 from the inlet 3-1 of the first chamber. The seawater forms a waterfall-like flow at the slit and then impacts the water surface below to simulate a wave-breaking process.

[0041] Centrifugal pump: Flow range 20-50L / min, adjustable by flow rate. 3. Wave breaking strength in the first chamber. First chamber: Length × Width × Height = 0.80m × 0.50m × 0.60m. First chamber inlet: Diameter 30mm.

[0042] like Figure 2 As shown, the overflow pipe 3-2 includes an inner pipe and an outer pipe arranged coaxially. The inner pipe has several distribution holes along its axial direction, and a horizontal slit is located on the outer pipe. The outer pipe has an inner diameter of 8cm and a length of 78cm, while the inner pipe has an inner diameter of 4cm and a length of 78cm. The water distribution holes in the inner pipe have a diameter of 5mm and are spaced 4cm apart. The slit is 30cm x 3mm (length x width) and is positioned 20cm above the water surface.

[0043] As the water level inside the first chamber 3 rises to the overflow port 3-3 on the right side (30cm vertically from the bottom), seawater overflows from the first chamber 3 and enters the second chamber 4. This ensures that the seawater depth inside the first chamber 3 remains at 30cm (this depth is designed to ensure that the plume of underwater bubbles flows naturally without being affected by the bottom of the chamber), and also allows the seawater inside the first chamber 3 to be updated in real time, so as to ensure that the sampling process in this artificially controlled environment can be as close as possible to field sampling.

[0044] The first tank overflow outlet is 30cm x 2cm long and 30cm from the bottom, with a vertical downward extension of 20cm.

[0045] First chamber air inlet: 6mm in diameter, located to the left of the horizontal center line of the chamber cover. First chamber air outlet: 6mm in diameter, located to the right of the horizontal center line of the chamber cover. First chamber pressure relief port 3-5: 6mm in diameter, located to the left of the first chamber air outlet.

[0046] Second tank: length × width × height = 0.30m × 0.50m × 0.35m; Second tank overflow outlet: length × width = 30cm × 2cm, 20cm from the bottom; Second tank outlet: diameter 30mm.

[0047] The design of the second chamber 4 is primarily to prevent external particulate matter from entering the headspace of the first chamber 3. If the second chamber were removed, particulate matter from the outside air could enter the first chamber 3 through the overflow port 3-3, thus affecting the aerosol sampling process in the headspace of the first chamber. Furthermore, extending and bending the overflow port on the right side of the first chamber below the water surface of the second chamber ensures the airtightness of the headspace of the first chamber. In addition, the second chamber 3 also serves as a buffer for subsequent multi-stage seawater filtration. As the volume of seawater flowing through the multi-stage filters (primary pre-filter 6, secondary pre-filter 7, and tertiary pre-filter 8) increases, the resistance also increases. Therefore, the seawater in the second chamber 4 can be discharged from the entire system through the overflow port 4-1 on its right side.

[0048] The primary pre-filter 6 has a filtration accuracy of 2 mm, the secondary pre-filter 7 has a filtration accuracy of 200 μm, and the tertiary pre-filter 8 has a filtration accuracy of 10 μm.

[0049] To further ensure that the overflow ports of the first tank 3 and the second tank 4 can smoothly discharge excess seawater, the overflow port of the second tank 4 is located 20cm from the bottom surface, which is lower than the overflow port of the first tank 3.

[0050] Seawater in the second tank 4 flows through three pre-filters (primary pre-filter 6, secondary pre-filter 7, and tertiary pre-filter 8) under the action of the rear diaphragm pump 10 to pre-filter large-diameter microplastics in the seawater. A pressure-sensing water valve 9 is installed at the front end of the diaphragm pump. If the pressure value of the diaphragm pump 10 is too high, it indicates that the pre-filter is overloaded. At this time, it is necessary to close the water valve 9 and replace the multi-stage pre-filter.

[0051] like Figure 4 As shown, the multi-stage pre-filter has the advantages of easy disassembly and replacement. It consists of two parts: a stainless steel screen tube for filtration and a stainless steel tube section for sealing. The two parts are connected as a whole by threads, and then both ends are connected to water pipes. The pore size of the stainless steel screen tube can be customized according to different experimental requirements, ranging from a few micrometers to a few millimeters. In this embodiment, the pore size of the end stainless steel screen is selected as 10 μm because microplastics smaller than 10 μm have a higher degree of aerosolization and atmospheric significance.

[0052] After pre-filtration, the seawater enters the pre-filtration collection tank 11 (length × width × height = 0.30m × 0.50m × 0.35m), where it is further filtered by polycarbonate membranes and glass frit filters. Finally, these polycarbonate membranes are stored in an environment of -20℃.

[0053] The aerosol generated by the wave-breaking in the air above the first chamber 3 is collected by the low-pressure cascaded impactor 5. The low-pressure cascaded impactor 5 is a multi-stage impactor sampler that determines the particle size distribution using aerodynamic principles. Figure 3 As shown in Table 1, the classification parameters are as follows. Microplastic particles with diameters ranging from 0.016 μm to 10 μm can be classified and collected. The microplastic particles were collected on a 25 mm diameter polycarbonate membrane for further analysis.

[0054] Table 1. Stage parameters in low-pressure cascade impactors for particulate matter.

[0055] series D50% [μm] series D50% [μm] 15 10 8 0.38 14 5.34 7 0.25 13 3.63 6 0.15 12 2.46 5 0.094 11 1.62 4 0.054 10 0.94 3 0.030 9 0.60 2 0.016

[0056] All housings, piping, and filters are made of non-plastic materials, including corrosion-resistant 316 stainless steel and glass, to minimize the generation of microplastic particles inside the system.

[0057] A method for detecting the aerosolization of microplastics at the ocean-air interface is as follows:

[0058] Seawater is pumped into the first tank to create a continuous wave-breaking process;

[0059] Particle-free air is introduced into the first chamber at a rate of 11 L / min through the inlet pipe, but the airflow exiting the outlet pipe is not sampled at this time. This state is maintained for 30 minutes to ensure that the particulate matter concentration in the gas exiting the outlet pipe stabilizes before sampling is performed.

[0060] After the aerosol generated in the headspace of the first chamber flows out from the outlet, it is collected by the low-pressure cascade impactor at a flow rate of 10L / min, and the sampling volume is recorded. The remaining 1L / min is discharged from the system through the pressure reducing tube (the slight positive pressure inside the system can not only reduce the airtightness requirements of the system, but also prevent external particles from entering the system).

[0061] The seawater in the second chamber was collected after pre-filtration, and then further filtered for microplastic particles smaller than 10μm in the seawater using a polycarbonate membrane and glass frit filter, and the sampling volume was recorded.

[0062] Microplastic particles on polycarbonate films were identified and counted using different light excitation channels of a fluorescence microscope.

[0063] The degree of aerosolization of microplastic particles within a certain particle size range is represented by their aerosolization factor (AF), and the specific formula is as follows:

[0064]

[0065] in, V is the number of microplastic particles within a certain size range on the polycarbonate membrane of a low-pressure cascade impactor. air It is the volume of air collected; V is the number of microplastic particles within a certain size range on the polycarbonate film of a glass frit core. water It is the volume of filtered seawater; and These represent the concentrations of microplastic particles within a specific particle size range in air and water.

[0066] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A detection system for the aerosolization of microplastics at the ocean-air interface, characterized in that: The first chamber is a closed chamber. The top cover of the first chamber is equipped with an air inlet and an air outlet. An overflow pipe is horizontally installed on the top of the first chamber. A horizontal slit is installed on the overflow pipe. The inlet of the overflow pipe is connected to seawater via a pump. The air inlet is connected to a clean air source, and the air outlet is connected to a low-pressure cascade impactor. An overflow port is installed at a set height of the first chamber. The distance between the overflow port and the bottom of the first chamber is greater than the distance between the horizontal slit and the overflow port. The second housing has a second overflow port; the first overflow port is connected to the second housing via a bent pipe; the height of the second overflow port is lower than the height of the first overflow port; the outlet end of the bent pipe is set lower than the second overflow port. The bottom outlet of the second chamber is connected in sequence to a multi-stage pre-filter and a glass core filter. The filter membrane of the glass core filter is a polycarbonate track-etched membrane.

2. The air-sea interface microplastic aerosolization detection system according to claim 1, characterized in that: The overflow pipe includes an inner pipe and an outer pipe arranged coaxially. The inner pipe has a number of liquid distribution holes arranged along the axial direction, and the horizontal slit is arranged on the outer pipe.

3. The air-sea interface microplastic aerosolization detection system according to claim 1, characterized in that: A pre-filtration collection tank is provided between the multi-stage pre-filter and the polycarbonate membrane-glass core filter.

4. The air-sea interface microplastic aerosolization detection system according to claim 1, characterized in that: The multi-stage pre-filter is a three-stage filter with filtration accuracies of 2mm, 200μm and 10μm respectively.

5. The detection method of the air-sea interface microplastic aerosolization detection system according to any one of claims 1-4, characterized in that: Includes the following steps: Clean air is introduced into the first chamber through the air intake pipe, while seawater, after being coarsely filtered, is continuously pumped into the overflow pipe at the top of the first chamber and forms a water flow at the horizontal slit, which impacts the water surface below, simulating the wave-breaking process and forming aerosols. The aerosols are collected by the low-pressure cascade impactor. The seawater overflowing from the first tank undergoes multi-stage pre-filtration, and then uses polycarbonate membranes and glass frit filters to filter out microplastic particles with a diameter of less than 10μm. Identification and counting of microplastic particles on polycarbonate films; Calculate the degree of aerosolization of microplastic particles.

6. The detection method according to claim 5, characterized in that: The aerosol formation and collection process maintains a slight positive pressure inside the first chamber.

7. The detection method according to claim 5, characterized in that: Microplastic particles on polycarbonate films were identified and counted using different light excitation channels of a fluorescence microscope.

8. The detection method according to claim 5, characterized in that: The degree of aerosolization of microplastic particles within a certain particle size range is represented by its aerosolization factor, and the specific formula is as follows: ； ； ； in, It refers to the number of microplastic particles within a certain size range on the polycarbonate membrane of a low-pressure cascade impactor. It is the volume of air collected; It refers to the number of microplastic particles within a certain size range on the polycarbonate film on the glass frit. It is the volume of filtered seawater; and These represent the concentrations of microplastic particles within a specific particle size range in air and water.

Images