CN108871875A - A kind of lake fine particle acquisition equipment - Google Patents

Abstract

The invention discloses a lake fine particle capture device, which comprises a support, a buoy timing release system and a number of collection tubes vertically placed in the support, with an open top and a closed bottom. The support is connected with a vertically upward hard The release rod has a length greater than or equal to the water depth of the lake, and the bottom is screwed to the bracket. The bottom of the bracket is provided with a bottom fixing rod protruding downwards, and the sides are respectively provided with side fixing rods protruding outward. The buoy timing release system includes wearing Through the timing lock, one end is connected to the middle of the bracket, and the other end is connected to the cable of the buoy. The timing lock is placed at the bottom of the water and is more than 20m away from the bracket. The total length of the cable satisfies: water depth≤L≤a+water depth/2, where L is the total length of the cable, a is the distance between the timing lock and the bracket. The device is simple in structure, easy to install, and has little disturbance to sediment during installation and collection, and is suitable for capturing fine particles in large eutrophic shallow lakes with severe wind waves and human disturbance.

Description

A lake fine particle capture device

technical field

The invention belongs to the field of lake environmental geochemistry, and relates to a multi-channel resuspension-sedimentation fine particle capture device for eutrophic shallow water lakes against wind and wave disturbance, especially suitable for severe wind and wave disturbance, large biomass of phytoplankton in water bodies, and resuspension-settling fine particles. The capture of sedimentation particles in eutrophic shallow lakes with high concentration of particulate pollutants can be used to observe the resuspension-sedimentation flux of shallow lakes and the research on the physical and chemical properties of water resuspension and algae-derived self-generated fine particles in time and space.

Background technique

The particle size of the surface sediment is usually about 80% below 50 μm, mainly silt and clay, and the depth of shallow lakes is usually below 6m. The loose surface sediment is easily disturbed by wind waves and resuspended, becoming a water body. fine particles in. For example, in large shallow lakes such as Taihu Lake and Chaohu Lake in China, the concentration of total suspended particulates in the water column can increase by up to dozens of times under a disturbance of a wind speed of 8 ms ^-1 . In addition, many large shallow lakes in my country are facing serious eutrophication problems. For example, typical severely eutrophic shallow lakes such as Taihu Lake, Chaohu Lake, and Dianchi Lake in my country have algal blooms lasting more than 250 days every year in recent years, and the largest area has reached more than 75% of the entire lake area. In large shallow lakes with such severe eutrophication, phytoplankton are one of the main sources of particulate matter in the water. Studies have shown that in shallow lakes with severe eutrophication, phytoplankton residues such as algae account for about 43% or even higher of fine particles in the water. In shallow lakes with severe eutrophication, it is of great significance to study the sedimentation flux and source of resuspended-sedimented fine particles in the water body for the practice of lake pollution remediation and the mechanism of material migration and transformation in aquatic ecosystems.

Traditional sedimentation particle traps are mostly used in marine water bodies (CN 2461855Y, CN 100539831C, CN103039411 B, CN 104122070 A, CN104458344 A, etc.). The lack of collection devices restricts the study of resuspended-sedimented fine particles in eutrophic shallow lakes. Some devices have focused on the capture of particulate matter in lake water (CN205120412 U, CN101162186 A), however, these devices are all buoy-anchored catchers. In the form of buoys floating on the water surface, the capture device is suspended in the water column. In shallow lakes, it is easily affected by wind and wave disturbance and vibrates greatly, and the underwater anchoring device is easily driven during the vibration process, resulting in loosening of the surface near the capture device. The sediment is resuspended and becomes fine particles in the water body, causing a sharp increase in the concentration of particulate matter in the water column around the capture device, increasing the amount of particulate matter that settles into the capture device, or causing the capture device to tilt or lodging, increasing the capture error of settled particles, and extremely The earth affects the accuracy of capture. In addition, large shallow lakes such as Taihu Lake and Chaohu Lake in my country have frequent human activities such as fishing and shipping. When the buoys of the particulate matter capture device float on the water surface, they are easily disturbed by human activities and even destroyed by them, making it difficult to capture particulate matter. In order to reduce the secondary disturbance caused by buoy anchoring and the damage caused to the capture device and the error caused by the capture of sedimentation particles, it is necessary to eliminate the disturbance of the device to the surrounding loose surface sediment during the process of device placement, capture and recovery, and reduce the The probability that it will be destroyed by a disturbance.

The problem of eutrophication in shallow lakes in my country is prominent, and algae-derived organic particles are an important part of lake sedimentation fine particles. However, the existing particle capture devices fail to consider the degradation of easily degradable organic components in fine sedimentation particles during the capture process, and cannot meet the needs of long-term research on the components of algae-derived organic particles. Usually, adding formalin or 1g/L NaCl solution to the particulate matter collection tube can prevent the degradation of organic components in the settled particulate matter. However, in large shallow lakes in my country, the exchange of water bodies caused by wind and wave disturbance, human disturbance, and changes in the hydrological environment is intense, and the traditional buoy-anchored trapping tube swings greatly, and the formalin or NaCl solution in it will quickly dissociate with the water column. The exchange of lake water in the lake makes it difficult to achieve the purpose of preventing the degradation of organic components in the sedimentation particles.

According to the reports of published patents or literatures, the problem of anti-wind wave disturbance and human disturbance of particle capture devices in shallow lakes with severe wind and wave disturbance has not yet been solved, and the problem of rapid degradation of sedimentary organic particle components in eutrophic shallow lakes is also a problem. could not be effectively resolved.

Contents of the invention

In view of the defects of the existing water particle capture devices, the present invention aims to provide a multi-channel resuspension-settling fine particle capture device suitable for large-scale eutrophic shallow lakes with severe wind waves and artificial disturbances. The installation and implementation process and excellent capture stability solve technical problems such as large resuspension-sedimentation fine particle capture errors in large eutrophic shallow lakes, and are vulnerable to wind waves and human disturbance damage.

In order to solve the problems of the technologies described above, the present invention adopts the following technical solutions:

A lake fine particle capture device, comprising:

Brackets, buoy timing release system and several catch tubes;

The trapping tube is vertically placed in the bracket, the top end of the trapping tube is open, and the bottom end is closed;

The support is connected with a vertically upward hard release rod, the length of the release rod is greater than or equal to the water depth of the lake, and the bottom of the release rod is screwed to the support;

The bottom of the bracket is provided with a downwardly protruding bottom fixing rod, and each side of the bracket is respectively provided with an outwardly protruding side fixing rod;

The buoy timing release system includes a timing lock, a cable and a buoy. One end of the cable is connected to the middle of the support, and the other end is connected to the buoy. The timing lock is placed at the bottom of the water and is more than 20m away from the support. The cable Through the buckle of the timing lock, the total length of the cable satisfies the following formula:

Water depth≤L≤a+water depth/2; wherein L is the total length of the cable, and a is the distance between the timing lock and the support.

Bottom and side fixing rods prevent the bracket from falling over, and cables in this length range can both prevent human surface activities from affecting the device when locked, and ensure that the buoy reaches the water surface when released.

Further, the bracket includes several vertical channels, the number of the channels is greater than or equal to the number of the collection tubes, and each of the channels accommodates one of the collection tubes. The vertically arranged channel can prevent the catch tube from falling down in the support.

Further, the channels are distributed symmetrically in a plan view.

Further, the bracket includes a flat bottom, a grid and a vertical support part, the grid is arranged above the bottom in parallel through the vertical support part, each square of the grid The grid and the bottom form the channel. The trapping tubes are placed on the flat bottom of the bracket to ensure that the trapping tubes are at the same height when collecting samples, and the grids of the grid can restrict the trapping tubes and prevent them from falling down.

Further, the whole of the bottom and the grid is square.

Further, there are four bottom fixing rods, which are respectively arranged under the four corners of the bottom.

Further, there are 8 side fixing rods in total, which are respectively arranged along the extension lines of the four sides of the bottom.

Further, the cables are connected to the middle of the grid.

Further, there are 4 to 16 trapping tubes.

Further, the collecting tube is made of transparent plexiglass.

Further, the height of the trapping tube is 20-80cm

Further, the height-to-diameter ratio of the trapping pipe is 5-10, which can be adapted to capture particulate matter in different types of shallow lakes with a water depth of 1 m to 6 m.

Further, the outer wall of the collection pipe is provided with a throat hoop, and the throat hoop is horizontally connected in the channel.

Further, the throat hoop is connected to the grid of the grid through a nylon cable tie or a stainless steel ring.

Further, the bracket is made of stainless steel.

Further, the delivery rod is composed of several sub-shooting rods with a length of 50 cm, and the sub-shooting rods are screwed to each other. The launch rod can be assembled on demand within the range of 50~600 cm, and can be assembled according to the depth of shallow lakes.

Further, the diameter of the delivery rod is 2cm.

Further, the bottom fixing rod or the side fixing rod is composed of several sub-fixing rods with a length of 20-100 cm, and the sub-fixing rods are screwed to each other. The fixing rods on the bottom and side make the capture device fixed in the sediment in the capture area, avoiding the disturbance and deviation of the capture tube caused by wind wave disturbance and human activities.

Further, the diameter of the bottom fixing rod or the side fixing rod is less than 2 cm, the contact area is small when it is fixed in the sediment, and it can be properly adjusted according to the sedimentation depth of the capture area, which reduces the need for feeding and recycling operations. Disturbance of loose sediment in the capture area during the process.

Further, the cable is made of polyethylene to avoid aging and abrasion when placed underwater for a long time.

Further, the diameter of the cable is less than 0.5 cm, and it is in a suspended state when underwater, and does not touch the surface sediment, so as to prevent disturbance to the surface sediment.

Further, the precision of the time lock is 1 minute. The time lock can release the buoy at any time within its maximum working time range. According to the different time series capture requirements of resuspension-sedimentation fine particles, the buoys can be released in time intervals to recover the captured sedimentation fine particles.

Further, the top of the collection tube is covered by a plexiglass screw cap or a nylon sieve with several through holes, so as to avoid interference from large aquatic animals and garbage during the collection of fine particles.

Further, the diameter of the through hole is 0.5 cm.

Further, the bottom end of the collection tube is closed with a screw cap to facilitate the recovery and research of the collected particles. At the same time, the covering device at the top of the collecting tube and the screw cap at the bottom end make cleaning and assembling more convenient during the recycling process of the collecting tube, and increase the recycling efficiency of the collecting tube.

Further, the collection pipe includes a main collection pipe and a secondary collection pipe, the secondary collection pipe is connected to the bottom of the main collection pipe, and the diameter of the connection is smaller than the diameter of the collection pipe, so that the collection The tube is in the shape of an hourglass as a whole, and a lightweight isolation pad is arranged in the neck of the hourglass, and the isolation pad is connected to the neck of the hourglass through an elastic connecting rope. The isolation pad is conical, and the isolation pad The base diameter is greater than the diameter of the neck of the hourglass. Since the spacer has a larger diameter than the neck, it can cover the hourglass neck under buoyancy.

Further, the spacer is a polypropylene spacer.

Further, the inclination angle of the neck of the hourglass is 45°.

Further, the neck diameter of the hourglass is 1 cm.

Further, the spacer is a hollow cone with a thickness of 0.1 cm.

Further, the aspect ratio of the main trapping pipe and the secondary trapping pipe is greater than or equal to 5.

Further, the trapping tube is filled with formalin or sodium chloride solution. When it is necessary to study the organic components in the particles, formalin or NaCl solution will be put in. The concentration of the commonly used NaCl solution is 1g/L.

Due to the light weight of the isolation pad, the monthly sedimentation of particulate matter in eutrophic shallow lakes can be as high as 50 kg dw m ^-2- due to violent wind and wave disturbance and cyanobacteria outbreaks. It takes about a week for organic matter such as blue-green algae particles to degrade, and the sedimentation during this period is enough to press the isolation pad to make the particles enter the secondary capture pipe. Float up quickly to seal the hourglass neck again. The spacer is conical, and when the neck of the hourglass is closed, the tip of the cone is upward, which facilitates the downward sliding of the settled particles and prevents the diffusion of formalin or NaCl solution in the auxiliary pipe. In addition, because the height-to-diameter ratio of the main capture pipe and the secondary pipe is above 5, the disturbance of the liquid in the capture pipe by wind and waves is greatly reduced, and the density of formalin or NaCl solution is greater than that of lake water, making it difficult to exchange to In the lake water, the combination of the capture main pipe and the capture sub-pipe further prevents formalin or NaCl solution from being exchanged into the lake water. According to the needs of the research on the easily degradable organic matter components in the fine sedimentation, this kind of overall hourglass-shaped collection pipe can be set up. The fine sedimentation can settle into the secondary collection pipe through the upper collection main pipe, but cannot The tube goes into the upper capture main. The sealing function of the isolation pad further prevents the exchange of formalin or 1g/L NaCl solution in the secondary trapping pipe with the lake water, so as to prevent the degradation of easily degradable organic matter components in the settled fine particles, and is used to study eutrophication Compositional characterization of algal-derived sedimentary organic particles in lakes.

The beneficial effects of the present invention are:

The device is simple in structure, easy to install, and has little disturbance to the sediment during installation and collection, and is suitable for capturing fine particles in large-scale eutrophic shallow lakes with severe wind waves and human disturbance. The device itself has technical problems such as large particle capture errors caused by violent shaking during the capture period, and is easily damaged by wind waves and human disturbances; It is a technical problem that it is difficult to accurately and targetedly study the organic components in particulate matter. The application of the present invention will improve the research on the pollution characteristics, flux characteristics, and temporal and spatial variation characteristics of fine particles settled in large-scale eutrophic shallow lakes.

Description of drawings

Fig. 1 is a schematic structural view of the lake fine particle capture device of the present invention.

Fig. 2 is a schematic diagram of the structure of the main capture pipe and the secondary capture pipe.

Fig. 3 is a schematic diagram of the structure of the delivery rod.

FIG. 4 is a schematic diagram of the structure of the isolation pad.

Among them, 1 is the release rod, 2 is the catch tube, 3 is the bracket, 4 is the side fixed rod, 5 is the bottom fixed rod, 6 is the buoy timing release system, 7 is the timing lock, 8 is the cable, 9 is the buoy, 10 is Screw cap, 11 is a throat hoop, 12 is a plexiglass screw cap or a nylon sieve that contains some through holes, 13 is a connecting thread for a throwing rod, and 14 is a spacer; 15 is a trapping secondary pipe.

Detailed ways

The present invention will be further described below in conjunction with specific implementation examples. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention.

As shown in Figure 1-4, a lake fine particle capture device includes:

A lake fine particle capture device, comprising:

Brackets, buoy timing release system and several catch tubes;

The trapping tube is vertically placed in the bracket, the top end of the trapping tube is open, and the bottom end is closed;

The support is connected with a vertically upward hard release rod, the length of the release rod is greater than or equal to the water depth of the lake, and the bottom of the release rod is screwed to the support;

The bottom of the bracket is provided with a downwardly protruding bottom fixing rod, and each side of the bracket is respectively provided with an outwardly protruding side fixing rod;

The buoy timing release system includes a timing lock, a cable and a buoy. One end of the cable is connected to the middle of the support, and the other end is connected to the buoy. The timing lock is placed at the bottom of the water and is more than 20m away from the support. The cable Through the buckle of the timing lock, the total length of the cable satisfies the following formula:

Water depth≤L≤a+water depth/2; wherein L is the total length of the cable, and a is the distance between the timing lock and the support.

Bottom and side fixing rods prevent the bracket from falling over, and cables in this length range can both prevent human surface activities from affecting the device when locked, and ensure that the buoy reaches the water surface when released.

The support includes several vertical passages, the number of the passages is greater than or equal to the number of the collection pipes, and each passage accommodates one collection pipe. The vertically arranged channel can prevent the catch tube from falling down in the support.

The channels are distributed symmetrically in a top view.

The support includes a flat bottom, a grid and a vertical support, the grid is arranged above the bottom in parallel through the vertical support, and each grid of the grid is connected to the bottom constitute the channel. The trapping tubes are placed on the flat bottom of the bracket to ensure that the trapping tubes are at the same height when collecting samples, and the grids of the grid can restrict the trapping tubes and prevent them from falling down.

The whole of the bottom and the grid is square.

There are 4 bottom fixing rods, which are respectively arranged under the four corners of the bottom.

There are 8 side fixing rods in total, which are respectively arranged along the extension lines of the four sides of the bottom.

The cables are connected to the middle of the grid.

There are 4-16 trapping tubes.

The collecting tube is made of transparent plexiglass.

The height of the trapping tube is 20-80cm

The height-to-diameter ratio of the trapping pipe is 5-10, which can be adapted to capture particulate matter in different types of shallow lakes with a water depth of 1 m to 6 m.

The outer wall of the collecting pipe is provided with a throat hoop, and the throat hoop is horizontally connected in the channel.

The throat hoop is connected to the grid of the grid through a nylon cable tie or a stainless steel ring.

The bracket is made of stainless steel.

The delivery rod is composed of several sub-shooting rods with a length of 50 cm, and the sub-shooting rods are screwed to each other. The launch rod can be assembled on demand within the range of 50~600 cm, and can be assembled according to the depth of shallow lakes.

The diameter of the delivery rod is 2cm.

The bottom fixing rod or the side fixing rod is composed of several sub-fixing rods with a length of 20-100 cm, and the sub-fixing rods are screwed to each other. The fixing rods on the bottom and side make the capture device fixed in the sediment in the capture area, avoiding the disturbance and deviation of the capture tube caused by wind wave disturbance and human activities.

The diameter of the bottom fixing rod or the side fixing rod is less than 2 cm, and the contact area is small when it is fixed in the sediment, and it can be properly adjusted according to the sedimentation depth of the capture area, which reduces the impact on the input and recovery operations. Disturbance of loose sediment in the capture area.

The cable is made of polyethylene to avoid aging and wear when it is placed underwater for a long time.

The diameter of the cable is less than 0.5 cm, and it is in a suspended state when it is underwater, and does not touch the surface sediment to prevent disturbance to the surface sediment.

The precision of the time lock is 1 minute. The time lock can release the buoy at any time within its maximum working time range. According to the different time series capture requirements of resuspension-sedimentation fine particles, the buoys can be released in time intervals to recover the captured sedimentation fine particles.

The top of the collection tube is covered by a plexiglass screw cap or a nylon sieve with several through holes to avoid interference from large aquatic animals and garbage during the collection of fine particles.

The diameter of the through hole is 0.5 cm.

The bottom end of the collection tube is closed with a screw cap to facilitate the recovery and research of the collected particles. At the same time, the covering device at the top of the collecting tube and the screw cap at the bottom end make cleaning and assembling more convenient during the recycling process of the collecting tube, and increase the recycling efficiency of the collecting tube.

The collection pipe includes a main collection pipe and a secondary collection pipe, the secondary collection pipe is connected to the bottom of the main collection pipe, and the diameter of the connection is smaller than the diameter of the collection pipe, so that the collection pipe as a whole Hourglass type, the neck of the hourglass is provided with a lightweight spacer, the spacer is connected to the neck of the hourglass through an elastic connecting rope, the spacer is conical, and the bottom diameter of the spacer is larger than The diameter of the neck of the hourglass. Since the spacer has a larger diameter than the neck, it can cover the hourglass neck under buoyancy.

The spacer is a polypropylene spacer.

The inclination angle of the neck of the hourglass is 45°.

The neck diameter of the hourglass is 1 cm.

The spacer is a hollow cone with a thickness of 0.1 cm.

The aspect ratios of the main collection pipe and the secondary collection pipe are both greater than or equal to 5.

The trapping tube is filled with formalin or sodium chloride solution. When it is necessary to study the organic components in the particles, formalin or NaCl solution will be put in. The concentration of the commonly used NaCl solution is 1g/L.

Due to the light weight of the isolation pad, the monthly sedimentation of particulate matter in eutrophic shallow lakes can be as high as 50 kg dw m ^-2 due to violent wind and wave disturbance and cyanobacteria outbreaks. It takes about a week for organic matter such as particles to degrade, and the sedimentation during this period is enough to press the isolation pad to make the particles enter the secondary capture pipe. When the particles enter the secondary capture pipe, the isolation pad will be under the action of the elastic connecting rope and buoyancy. Quickly float to seal the hourglass neck again. The spacer is conical, and when the neck of the hourglass is closed, the tip of the cone is upward, which facilitates the downward sliding of the settled particles and prevents the diffusion of formalin or NaCl solution in the auxiliary pipe. In addition, because the height-to-diameter ratio of the main capture pipe and the secondary pipe is above 5, the disturbance of the liquid in the capture pipe by wind and waves is greatly reduced, and the density of formalin or NaCl solution is greater than that of lake water, making it difficult to exchange to In the lake water, the combination of the capture main pipe and the capture sub-pipe further prevents formalin or NaCl solution from being exchanged into the lake water. According to the needs of the research on the easily degradable organic matter components in the fine sedimentation particles, such an overall hourglass-shaped collection pipe can be set up. The fine sedimentation particles can settle into the secondary collection pipe through the upper collection main pipe, and cannot pass through the secondary collection pipe. The tube goes into the upper capture main. The sealing function of the isolation pad further prevents the exchange of formalin or 1g/L NaCl solution in the secondary trapping pipe with the lake water, so as to prevent the degradation of easily degradable organic matter components in the settled fine particles, and is used for the study of eutrophication Compositional characterization of algal-derived sedimentary organic particles in lakes.

The assembly of the capture device includes: the investigation of the water level in the capture area and the depth of the underwater silt, the assembly of the capture pipe and the bracket, the installation of the bottom fixed rod and the side fixed rod, the connection of the release rod, and the connection of the buoy timing release system.

(1) Investigation of the water level and underwater silt depth in the target capture area. In view of the large fluctuations in the water level of a large number of shallow lakes (especially large river-connected lakes), it is necessary to investigate the real-time water level status of the target water area before launching the capture device, and infer the possible water level of the target water area within the capture cycle based on the historical water level status. Variation range to set the delivery rod and cable length according to the actual situation. In addition, the sedimentation status of shallow lakes in different areas is significantly different, especially in some estuary areas, where the sedimentation depth is relatively large. In view of this situation, it is necessary to investigate the underwater sedimentation depth of the target area before implementing the capture of fine sedimentation particles. Adjust the length of the bottom fixing rod and the side fixing rod of the capture device according to the actual silting conditions.

(2) Assemble the catch tube and bracket. According to the collection purpose and recovery requirements under different collection times, different numbers of collection pipes 2 are provided. In each recovery cycle, set at least two sets of trapping tubes as parallel samples. If it is necessary to study the easily degradable organic matter components in the settled fine particles, the sub-pipe 15 must be connected to the lower part of the main trap, and both the sub-pipe and the main tube should be filled with formalin or 1g/L NaCl solution to To prevent the degradation of organic matter after the particles settle, at the same time, set up a control tube that does not contain formalin and 1g/L NaCl solution. The trapping main pipe and the trapping sub-pipe are funnel-shaped, and are separated by an isolation pad 14, so that the particles can settle into the sub-pipe through the main pipe, while the formalin or 1g/L NaCl solution and the particles are difficult to diffuse or rise, so as to prevent Loss of formalin or 1g/L NaCl solution and escape of settled particles under disturbance. Usually, according to the research needs of organic matter components, at least 4 trapping tubes must be installed in each recovery cycle, and the number of trapping tubes should be increased synchronously according to the increment of the recovery cycle. If necessary, multiple sets of capture devices can be deployed at the same time for particle capture and recovery research. After determining the number of capture tubes, select brackets 3 with different channels according to the number of capture tubes, and use nylon cable ties or stainless steel rings to connect and fix the capture tubes 2 and brackets 3 through throat hoops 11, thus completing the capture tube Assembly with trap holder.

(3) Installation of anti-disturbance fixed accessories. According to the silt depth of the target capture area, select the appropriate length of the bottom fixing rod and the side fixing rod. The length of the bottom fixing rod 5 is 20 cm greater than the depth of the mud, and its length ranges from 20 cm to 100 cm; the length of the side fixing rod 4 ranges from 20 cm to 100 cm. In view of the relatively fixed capture area, relatively stable silt depth, and long capture period, the fixed rod can be welded to the bottom and side of the support to facilitate long-term sequence of sedimentation particle capture research; for scattered capture areas, silt depth For studies with large differences, the fixed rods can be riveted in sections of 10 cm each to adapt to changes in the capture area and silt depth.

(4) Rigid delivery rod connection. According to the survey results of the water depth in the target capture area, select the appropriate length of the hard release rod. The delivery rod 1 is connected with the support 3, and several sub-shooting rods are connected according to the water depth difference to make the delivery rod reach the selected length.

(5) The buoy releases the system connection at regular intervals. The buoy is connected to the middle part of the support by using a cable 8 made of polymer polyethylene material with a diameter less than 0.5 cm, and the length of the cable between the buoy timing release device 6 and the support 3 is more than 20 m to increase the distance between the release device and the capture. distance to reduce the impact of the release device on the capture of settled fine particles. Simultaneously, cable 8 passes timing lock 7, and timing lock 7 is in closed state, and cable is locked on timing lock 7. After the above buoy timing release system is connected, the opening time of the timing lock 7 can be set according to the capture cycle, which can be set arbitrarily within 1 day to 6 months, with an accuracy of 1 minute.

2. Launching and recovery of capture devices, mainly including launch and fixation of brackets, release of buoy timing release system and recovery of capture devices.

(1) The bracket is placed and fixed. In the target catch water area, firmly hold the release rod 1 to place the bracket 3 stably on the bottom of the water, and press down the bottom fixing rod 5 of the bracket 3 to insert into the mud, and the insertion depth is 10~20cm greater than the depth of the mud, so that the bracket 3 fastened in the mud. Subsequently, gently rotate the delivery rod 1 to take it out from the support 3 .

(2) The buoy is released by the timing release system. Gently put the buoy timing release system 6 connected to the capture bracket 3 underwater about 20 m away from the bracket 3, and suspend the bracket 3 and the cable of the buoy timing release system 6 underwater without disturbing the capture Loose sediment in the area.

(3) Capture device recovery. Prepare incubators, PTFE sample bottles and ice cubes in advance in the room, and rush to the target water area 1 hour before the time lock 7 on the buoy timing release system 6 is opened, and do a good job of on-site hydration environment measurement and uploading. Preparatory work such as collection of covered water samples. After waiting for time lock 7 to open, find the buoy 9 that releases, and capture device is taken out by it. After the capture device is taken out, the settled fine particles collected in the capture tube shall be photographed, classified and stored and followed up for analysis. There are two recovery methods, one is to assemble capture devices with different channels (4~16 channels), and recover the capture devices in batches at different time gradients; or, install the capture tubes for multiple time series studies in the same In the capture device, the capture tubes are recovered in batches at different time gradients, and each recovery is completed quickly and vertically lifted to reduce the disturbance of the surface sediment in the capture area during the water outlet and water entry process of the capture device.

Example 1: Capture of resuspension-sedimentation fine particles in an estuary area of Chaohu Lake.

Chaohu Lake is a typical shallow lake with eutrophication. From May to November every year, algae outbreaks are serious, and the maximum outbreak area reaches more than 65% of the entire lake surface. At the same time, Chaohu Lake has a high pollution load, especially some rivers entering the lake in the northwest, which have input a large amount of pollutants for a long time, and deposited them in the estuary area in the form of particulate matter adsorption and sedimentation. However, Chaohu Lake is a typical large-scale eutrophic shallow lake with strong wind and wave disturbance and frequent human activities. The multi-channel resuspension-sedimentation lake fine particle capture device for eutrophic shallow water anti-wind and wave disturbance of the present invention effectively solves the problem of strong wind and wave disturbance, Sedimentary fine particle capture problem in shallow lake estuary area with frequent human activities.

(1) The average water depth in the target capture area is 3.5 m, and the average silt depth is 50 cm. In view of this feature, the length of the bottom fixing rod and the side fixing rod are each 70 cm. In order to study whether the organic matter of sedimentation fine particles comes from the channel entering the lake or the algae outbreak, a capture method with a secondary capture pipe was installed. Every half month is a capture cycle, and a control group without adding 1g/L NaCl solution is set up. Each capture cycle in each group has 4 capture tubes as parallel samples, and a total of 16 capture tubes are set. capture channel. The release period of the buoy timing release system is 15 days, and the distance from the capture support is 30 m. Through the buoy timing release system, release and recover once every 15 days, a total of 8 trapping tubes in the recovery organic particle group and the control group; release once every 30 days.

(2) By using the lake fine particle capture device, the impact of wind waves and human disturbance on particle capture was prevented. In the one-year capture study, the particle deposition was between 5 and 60 kg dw m ^-2 month ^-1 , and no The device was disturbed, lodging and damaged, and the recovery success rate reached 100%.

(3) Immediately after the fine sedimentation was recovered, it was refrigerated at -4 °C and transported to the laboratory. For the part that needs to be analyzed for the characteristics of organic matter components, it was frozen at -20 °C, vacuum freeze-dried, and analyzed by three-dimensional fluorescence analysis. The characteristics of organic matter components were analyzed. It was found that the organic matter components in the subsidence fine particles in the estuary area of the lake are mainly terrigenous humus, accounting for more than 75%. The authigenic organic matter component of the lake only accounts for about 25%. This device plays an important role in the capture and component research of resuspended-sedimented fine particles in the estuary area of shallow lakes.

Example 2: Capture of resuspension-sedimentation fine particles in typical grass and algal lakes of Taihu Lake

Taihu Lake is a typical eutrophic lake located in the middle and lower reaches of the Yangtze River. In recent years, the annual algal blooms have lasted for more than 250 days, and the largest area has reached more than 75% of the entire lake area. The intensification of algal blooms and the continuous degradation of submerged vegetation have It has become a severe environmental problem that Taihu Lake is facing. Since the 1980s, the species of aquatic plants in Taihu Lake has dropped from 66 to 17, and the coverage of submerged plants has dropped from 25% to 17%. Submerged plants play an important role in preventing sediment resuspension and purifying lake water quality in shallow lakes. The multi-channel resuspension-sedimentation lake fine particle capture device of the present invention effectively solves the problem of fine particle capture in grass-type and algae-type lake areas with significant differences between wind wave disturbance and human disturbance.

(1) The water depth in the algae-type lake area is 2m, the average silt depth is 30 cm, and the accumulation of algae is prominent; the water depth in the grass-type lake area is 1.5 m, the average silt depth is 40 cm, and the aquatic plants grow densely, mainly including Aphrodisiac, Anabaena, Foxtail algae, water chestnut, water chestnut and other aquatic plants. In view of the above characteristics, the lengths of the bottom fixed rod and the side fixed rods of the algae-type area capture device are each 50 cm, and the lengths of the bottom fixed rod and the side fixed rods of the grass-type area capture device are respectively 60 cm. In order to study the sedimentation amount of fine particles and the difference in organic matter components in the grass and algae lake area, a control group without adding 1g/L NaCl solution was set up, and each group had 4 capture tubes for each capture cycle. as a parallel sample. The release cycle of the buoy timing release system is 30 days, 30 m away from the capture support, and every 30 days is a capture cycle.

(2) Through a year-long capture study on grass and algae lakes, it was found that the sedimentation flux in grass lakes was between 3 and 20kgdw m ^-2 month ^-1 , while that in algae lakes was between 10 ^and 50kg dw m -1 ² months ^-1 room. The subsidence flux in the grass-type lake area is significantly smaller than that in the algae-type lake area, indicating that the impact of wind and wave disturbance on the grass-type lake area is less than that in the algae-type lake area. There was no disturbance, lodging or damage to the device, and the recovery success rate reached 100%.

(3) Immediately after the fine sedimentation was recovered, it was refrigerated at -4 °C and transported to the laboratory. For the part that needs to be analyzed for the characteristics of organic matter components, it was frozen at -20 °C, vacuum freeze-dried, and analyzed by three-dimensional fluorescence analysis. The characteristics of organic matter components were analyzed. The results showed that the organic matter in the subsidence fine particles in the grass-type lake area is mainly humus, while the content of authigenic proteins in the algae-type lake area is higher, which shows the significant difference in the organic matter components and sources in the subsidence fine particles in the grass-type lake area and algae-type lake area.

Claims (10)

1. A lake fine particle capture device, characterized in that it comprises: Brackets, buoy timing release system and several catch tubes; The trapping tube is vertically placed in the bracket, the top end of the trapping tube is open, and the bottom end is closed; The support is connected with a vertically upward hard release rod, the length of the release rod is greater than or equal to the water depth of the lake, and the bottom of the release rod is screwed to the support; The bottom of the bracket is provided with a downwardly protruding bottom fixing rod, and each side of the bracket is respectively provided with an outwardly protruding side fixing rod; The buoy timing release system includes a timing lock, a cable and a buoy. One end of the cable is connected to the middle of the support, and the other end is connected to the buoy. The timing lock is placed at the bottom of the water and is more than 20m away from the support. The cable Through the buckle of the timing lock, the total length of the cable satisfies the following formula: Water depth≤L≤a+water depth/2; wherein L is the total length of the cable, and a is the distance between the timing lock and the bracket. 2. The lake fine particle capture device according to claim 1, wherein the support includes several vertical passages, the number of the passages is greater than or equal to the number of the collection pipes, and each passage accommodates one of the catch tubes. 3. The lake fine particle capture device according to claim 2, characterized in that, the support comprises a flat bottom, a grid and a vertical support, and the grid passes through the vertical support in parallel It is arranged above the bottom, and each square of the square grid and the bottom form the channel. 4. The lake fine particle capture device according to claim 1, characterized in that there are 4 to 16 capture tubes. 5. The lake fine particulate matter capture device according to claim 1, characterized in that, the aspect ratio of the capture tube is 5-10. 6 . The lake fine particle capture device according to claim 2 , wherein a throat hoop is provided on the outer wall of the collection pipe, and the throat hoop is horizontally connected in the channel. 7 . 7. The lake fine particle capture device according to claim 1, characterized in that, the release rod is composed of several sub-release rods, and the sub-release rods are screwed to each other. 8. The lake fine particle capture device according to claim 1, characterized in that, the top of the capture pipe is covered by a plexiglass screw cap or a nylon sieve with several through holes. 9. The lake fine particle capture device according to claim 1, wherein the capture pipe includes a main capture pipe and a secondary capture pipe, and the secondary capture pipe is connected to the bottom of the main capture main pipe, connected to The diameter at the place is smaller than the diameter of the catch pipe, so that the catch pipe is hourglass-shaped as a whole, and a lightweight isolation pad is arranged in the neck of the hourglass, and the isolation pad is connected to the neck of the hourglass by an elastic connecting rope. The spacer is conical, and the diameter of the bottom of the spacer is larger than the diameter of the neck of the hourglass. 10. The lake fine particulate matter capture device according to claim 1, characterized in that formalin or sodium chloride solution is housed in the capture pipe.