Device and method for correcting photosynthetic activity turbidity of floating algae

Abstract

The invention discloses a device and a method for correcting photosynthetic activity turbidity of planktonic algae, and belongs to the technical field of planktonic algae monitoring, the device comprises an excitation emission optical structure, a light source driving module, a signal detection module and a main control module; according to the method disclosed by the invention, the relative increment relation between the turbidity scattering of the water body and the initial fluorescence is constructed by measuring a 750 nm water body turbidity scattering and combined light-induced fluorescence dynamic curve, and the influence of the turbidity scattering of the water body on the photosynthetic activity detection of the floating algae is corrected by calculating the correlation coefficient of the turbidity scattering of the water body and substituting the correlation coefficient into a photosynthetic activity correction model. The device is simple in structure, short in measurement period and non-invasive, can be used for underwater in-situ detection of the photosynthetic activity of the floating algae in a turbid water body, and provides a new way for rapid and accurate measurement of the photosynthetic activity of the floating algae.

Description

Technical Field

[0001] The invention belongs to the technical field of phytoplankton monitoring, and in particular relates to a device and method for correcting turbidity of phytoplankton photosynthetic activity. Background Art

[0002] Phytoplankton plays an important role in aquatic ecosystems, and its photosynthetic activity is crucial for assessing the health and function of ecosystems. However, turbidity in natural water bodies can significantly interfere with the measurement of phytoplankton photosynthetic activity. Existing measurement technologies often fail to effectively remove the influence of turbidity, resulting in large deviations in measurement results, which affects subsequent analysis and research of ecosystems. There is an urgent need for a device and method that can accurately correct the influence of turbidity. Summary of the invention

[0003] In order to solve the above technical problems, the present invention provides a device and method for correcting the turbidity of photosynthetic activity of phytoplankton.

[0004] The objective of the present invention is achieved through the following technical solutions:

[0005] In a first aspect, the present invention provides a turbidity correction device for photosynthetic activity of phytoplankton, including an excitation emission optical structure, a light source driving module, a signal detection module and a main control module;

[0006] The excitation emission optical structure includes a light-shielding sample chamber, a light source and a photomultiplier tube. The light source is vertically arranged above the light-shielding sample chamber, and is arranged around the photomultiplier tube and forms an angle with the photomultiplier tube. A narrow-band filter, a long-wave pass filter, a focusing lens and a collimating lens are sequentially arranged at the front end of the photomultiplier tube. The light source includes a lamp bead, a first laser diode and a second laser diode. Light source focusing lenses are respectively arranged at the front ends of the lamp bead, the first laser diode and the second laser diode.

[0007] The light source driving module includes an operational amplifier, a linear voltage regulator, a MOS tube driver and a MOS tube; a 16-bit digital / analog converter, an operational amplifier, a linear voltage regulator and a laser diode are connected in sequence, a universal input / output interface, a MOS tube driver, a MOS tube and a laser diode are connected in sequence, and the laser diode includes a first laser diode and a second laser diode; the 16-bit digital / analog converter of the main control module outputs an amplitude-adjustable voltage through the operational amplifier, and the linear voltage regulator is voltage-regulated to realize dynamic control of the excitation light intensity; the GPIO port of the main control module outputs a pulse signal to control the MOS tube driver and the switch circuit composed of the MOS tube to drive the excitation light source to generate a variable light pulse signal;

[0008] The signal detection module includes a dual-channel analog switch, a scattered light signal detection channel and a fluorescence dynamics signal detection channel; the scattered light signal detection channel includes an operational amplifier and an integral amplifier; the fluorescence dynamics signal detection channel includes a USB communication circuit, an FPGA circuit, a fluorescence 16-bit digital / analog converter, and a fluorescence preamplifier; the 16-bit analog / digital converter, the operational amplifier, the integral amplifier and the dual-channel analog switch are connected in sequence; the UART communication interface, the USB communication circuit, the FPGA circuit, the fluorescence 16-bit digital / analog converter, the fluorescence preamplifier and the dual-channel analog switch are connected in sequence; the dual-channel analog switch is connected to a photomultiplier tube;

[0009] The main control module includes a Cortex-M8 processor, a 16-bit digital / analog converter, a 16-bit analog / digital converter, a universal input and output interface, a UART communication interface, a touch liquid crystal display and peripheral circuits to realize light source control, signal detection module data acquisition, data analysis and processing, and device input and output control.

[0010] Furthermore, the lamp bead is a 750nm LED lamp bead, the first laser diode is a 445nm laser diode, the second laser diode is a 632nm laser diode, the long-wave pass filter is a 670nm long-wave pass filter, and the narrow-band filter is a 685nm narrow-band filter.

[0011] Furthermore, the angles between the lamp bead, the first laser diode, the second laser diode and the photomultiplier tube are 45 degrees.

[0012] Furthermore, the lamp beads, the first laser diode and the second laser diode are arranged at equal intervals along the circumferential direction.

[0013] Furthermore, the power of the first laser diode is 1.6W, and the power of the second laser diode is 1.2W.

[0014] Furthermore, the light-shielding sample chamber is made of black nylon, with an opening at the top and a hollow bottom, which prevents exposure to external ambient light while not affecting the fluidity of the water sample.

[0015] Furthermore, the long-wave pass filter is a HB670 material filter, and the narrow-band filter is a BP685 interference filter.

[0016] Furthermore, the signal detection is divided into two parts: scattered light signal detection and fluorescence kinetic signal detection;

[0017] In a second aspect, the present invention also provides a method for correcting turbidity of photosynthetic activity of phytoplankton, the specific steps of which are as follows:

[0018] Step 1: Collect water samples with different spatial distributions in the study area. The water samples with the same spatial distribution are divided into an experimental group and a control group. The experimental group is the original water sample containing water turbidity information, and the control group is the water sample that does not contain or contains a small amount of water turbidity information after sedimentation, stratification and filtration enrichment treatment;

[0019] Step 2: Use the device to measure the turbidity scattering information of the experimental group at 750nm and construct a scattering matrix;

[0020] Step 3: Use the device to measure the single-turnover fluorescence kinetic curves of the experimental group and the control group, perform maximum value normalization on the fluorescence kinetic curves, obtain the initial fluorescence by fitting and inversion, and construct the initial fluorescence relative increment matrix;

[0021] Step 4: Input the scattering matrix and the relative increment matrix into the correlation coefficient model to calculate the correlation coefficient;

[0022] Step 5: Input the correlation coefficient into the photosynthetic activity turbidity correction model to correct the effect of water turbidity scattering on the photosynthetic activity of phytoplankton.

[0023] Further, the experimental group and the control group have the same chlorophyll content;

[0024] Furthermore, the scattering matrix is ​​Turb=[t1,…t i …,t N ], where Turb is the scattering matrix, t i is the scattering of experimental group i, and N is the total number of experimental groups;

[0025] Furthermore, the maximum fluorescence F M The turbidity scattering of water will raise the base value of the initial fluorescence F0, thus affecting the photosynthetic activity F V / F M Measurement results;

[0026] Furthermore, the initial fluorescence relative increment matrix is , where ΔF0 is the initial fluorescence relative increment matrix, is the initial fluorescence of experimental group i, is the initial fluorescence of control group i;

[0027] Furthermore, the correlation coefficient model is A=[a1 … a i … a N ] T =ΔF0·Turb T ·(Turb·Turb T ) -1 , where A is the correlation coefficient matrix, a iis the correlation coefficient between experimental group i and control group i;

[0028] Furthermore, the correlation coefficient is , where α is the correlation coefficient;

[0029] Furthermore, the photosynthetic activity turbidity correction model is F V / F M =1-F'0 / F M ·(1-α·Turb), where F V / F M is the photosynthetic activity after turbidity correction, F'0 is the initial fluorescence before turbidity correction, F M is the maximum fluorescence.

[0030] Beneficial effects:

[0031] The present invention measures the 750nm water turbidity scattering and the combined light-induced fluorescence kinetic curve to construct the relative increment relationship between water turbidity scattering and initial fluorescence, and calculates the correlation coefficient between the two and brings them into the photosynthetic activity correction model to correct the influence of water turbidity scattering on the detection of phytoplankton photosynthetic activity. The device has a simple structure, a short measurement cycle, and is non-invasive. It can perform underwater in-situ detection of phytoplankton photosynthetic activity in turbid water bodies, providing a new way to quickly and accurately measure the photosynthetic activity of phytoplankton. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 A schematic diagram of a method for correcting turbidity of photosynthetic activity of phytoplankton;

[0033] Figure 2 It is a schematic diagram of the measuring device of the present invention;

[0034] Figure 3 It is a schematic diagram of the connection between the excitation emission optical structure, the light source driving module, the signal detection module and the main control module;

[0035] Figure 4 Schematic diagram of the optical structure for excitation emission (I);

[0036] Figure 5 Schematic diagram of the optical structure for excitation emission (II);

[0037] Figure 6 Schematic diagram of the optical structure for excitation emission (III);

[0038] Figure 7 Schematic diagram of the optical structure for excitation emission (IV);

[0039] Figure 8 Schematic diagram of optical simulation of excitation emission optical structure;

[0040] Fig. 9is the relationship diagram between the correlation coefficient α and 750nm;

[0041] Fig.10 is the F of the actual water body experimental group, the experimental group after correction, and the control group V / F M Comparison chart.

[0042] Among them, 10 is an excitation emission optical structure, 10a is a light shielding sample chamber, 10b is a light source focusing lens, 10c is a lamp bead, 10d is a light source fixing plate, 10e is a photomultiplier tube, 10f is a narrow band filter, 10g is a first laser diode, 10h is a long wave pass filter, 10i is a focusing lens, 10j is a collimating lens, and 10k is a second laser diode;

[0043] 20 is a light source driving module, 20a is a linear regulator, 20b is an operational amplifier, 20c is a MOS tube, and 20d is a MOS tube driver;

[0044] 30 is a signal detection module, 30a is a dual-channel analog switch, 30b is an integrating amplifier, 30c is an operational amplifier, 30d is a fluorescence preamplifier, 30e is a fluorescence 16-bit digital / analog converter, 30f is an FPGA circuit, and 30g is a USB communication circuit;

[0045] 40 is a main control module, 40a is a 16-bit digital / analog converter, 40b is a general input and output interface, 40c is a 16-bit analog / digital converter, and 40d is a UART communication interface. DETAILED DESCRIPTION

[0046] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. However, the following embodiments are limited to explaining the present invention, and the protection scope of the present invention should include the entire contents of the claims, and through the description of the following embodiments, those skilled in the art can fully implement the entire contents of the claims of the present invention.

[0047] Example

[0048] like Figure 1 As shown, a method for correcting turbidity of photosynthetic activity of phytoplankton is provided, and the specific steps are as follows:

[0049] 1. Measure the turbidity scattering of water at 750nm in N experimental groups and construct a 1×N order scattering matrix Turb;

[0050] 2. Measure the fluorescence kinetic curves of N experimental groups within 0-200μs, and obtain the initial fluorescence of N groups by curve fitting inversion ;

[0051] 3. Measure the fluorescence kinetic curves of N control groups within 0-200μs, and obtain the initial fluorescence of N groups by curve fitting inversion ;

[0052] 4. According to the initial fluorescence of the experimental group and the initial fluorescence of the control group Calculate the 1×N order initial fluorescence relative increment matrix ΔF0;

[0053] 5. Calculate the N×1 order correlation coefficient matrix A based on the scattering matrix Turb and the initial fluorescence increment matrix ΔF0, average all elements of the matrix A to obtain the correlation coefficient α;

[0054] 6. Input the correlation coefficient α into the photosynthetic activity turbidity correction model to correct the effect of water turbidity scattering in the study area on the photosynthetic activity of phytoplankton.

[0055] like Figure 2 As shown, a turbidity correction device for photosynthetic activity of phytoplankton includes an excitation emission optical structure 10, a light source driving module 20, a signal detection module 30 and a main control module 40, wherein the excitation emission optical structure 10 (such as Figure 4 , Figure 5 , Figure 6 and Figure 7 ) includes a light shielding sample chamber 10a, a light source fixing plate 10d, a lamp bead 10c, a first laser diode 10g, a second laser diode 10k, a light source focusing lens 10b, a photomultiplier tube 10e, a narrow band filter 10f, a long wave pass filter 10h, a focusing lens 10i, and a collimating lens 10j; Figure 8 Schematic diagram of optical simulation of excitation emission optical structure.

[0056] The light source driving module 20, the signal detection module 30 and the main control module 40 are as follows Figure 3 As shown, the light source driving module 20 includes an operational amplifier 20b, a linear regulator 20a, a MOS tube driver 20d, a MOS tube 20c and other peripheral circuits;

[0057] The signal detection module 30 includes a dual-channel analog switch 30a, an integral amplifier 30b and an operational amplifier 30c, a fluorescence preamplifier 30d, a 16-bit digital / analog converter (sampling rate 1MSPS) 30e, an FPGA circuit 30f and a USB communication circuit 30g and other peripheral circuits. When detecting scattered light signals, the dual-channel analog switch 30a is switched to the scattered light signal detection channel, and the main control module 40 lights up the lamp bead 10c through the light source driving module 20. The excitation light is converged into a light spot through the focusing mirror 10b to illuminate the water sample in the light-shielding sample chamber 10a to form scattered light. The scattered light passes through the collimating mirror 10j, the focusing mirror 10i, and the long-wave pass filter 10h. The narrow-band filter 10f is received by the photomultiplier tube 10e and converted into an electrical signal. The electrical signal enters the scattered light signal detection channel through the dual-channel analog switch 30a, and is amplified and then received by the 16-bit analog / digital converter 40c of the main control module 40. When the fluorescence dynamics signal is detected, the main control module 40 lights up the first laser diode and the second laser diode through the light source driving module 20, and the excitation light is converged into a light spot through the light source focusing lens 10b to induce the water sample in the light-shielding sample chamber 10a to produce fluorescence. The fluorescence is converged by the collimator 10j and the focusing lens 10i, and then the stray light is filtered out by the long-wave pass filter 10h and the narrow-band filter 10f, and is converted into an electrical signal by the photomultiplier tube 10e. The signal enters the fluorescence dynamics signal detection channel through the dual-channel analog switch 30a, and the fluorescence preamplifier 30d performs pre-filtering and amplification on the fluorescence signal, and then it is collected by the high-speed data acquisition circuit. The collected data is output to the main control module through DMA, which can realize the accurate measurement of the single-turn fluorescence dynamics rising process within 200us.

[0058] The main control module 40 is based on the Cortex-M8 processor, combined with a 16-bit digital / analog converter 40a, a 16-bit analog / digital converter 40c, a universal input and output interface 40b, a UART communication interface 40d, a touch LCD display and peripheral circuits to achieve light source control, signal detection module data collection, data analysis and processing, and device input and output control.

[0059] When performing scattered light signal detection, the main control module 40 lights up the 750nmLED through the light source driving module 20, and at the same time, the photomultiplier tube 10e detects the scattered light signal of the water sample in the light-shielding sample chamber 10a and converts it into an electrical signal, which enters the scattered light signal detection channel through the dual-channel analog switch 30a, and the integral amplifier 30b integrates and amplifies the current signal, and then inputs the voltage follower buffer isolation, and is received by the 16-bit analog / digital converter 40a of the main control module to complete the scattered light signal detection; when performing fluorescence dynamics signal detection, the main control module 40 lights up the first laser diode 10g and the second laser diode through the light source driving module 20 10k, the excitation light is converged into a light spot through the light source focusing lens 10b to induce the water sample in the light-shielding sample chamber 10a to produce fluorescence, and the fluorescence is converged through the collimator 10j and the focusing lens 10i, and then filtered through the long-wave filter 10h and the narrow-band filter 10f to remove stray light, and converted into an electrical signal by the photomultiplier tube 10e. The signal enters the fluorescence dynamics signal detection channel through the dual-channel analog switch 30a, and the fluorescence preamplifier 30d performs pre-filtering and amplification on the fluorescence signal, and then it is collected by the high-speed data acquisition circuit, and the collected data is output to the main control module 40 through DMA, which can realize the accurate measurement of the single-turn fluorescence dynamics rising process within 200us.

[0060] Specifically, the turbidity correction effect of phytoplankton photosynthetic activity is:

[0061] Tongling West Lake Wetland Park was selected as the research area, and water samples with different spatial distributions were collected. The original water samples were used as the experimental group, and the original water samples after sedimentation, stratification and filtration enrichment were used as the control group. First, the device was used to measure the 750nm scattering of the experimental group to obtain the scattering matrix. Then, the fluorescence kinetic curves of the experimental group and the control group were measured by the device, and the initial fluorescence was obtained by fitting and inversion. The initial fluorescence relative increment matrix was calculated, and the correlation coefficient was calculated according to the scattering matrix and the initial fluorescence relative increment matrix, as shown in Figure 2. Fig. 9 As shown, the correlation coefficient α is 0.001. The correlation coefficient α is input into the photosynthetic activity turbidity correction model to measure the photosynthetic activity of water samples with different spatial distributions in the study area. The results are as follows Fig.10 As shown in the figure, the photosynthetic activity after correction was basically consistent with that of the control group, indicating that the measurement results of photosynthetic activity were highly accurate.

[0062] The above description is only a specific implementation of the present application, so that those skilled in the art can understand or implement the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest range consistent with the principles and novel features applied for herein.

Claims

1. A turbidity correction device for photosynthetic activity of phytoplankton, characterized in that: It includes an excitation emission optical structure, a light source driving module, a signal detection module and a main control module; The excitation emission optical structure includes a light-shielding sample chamber, a light source and a photomultiplier tube. The light source is vertically arranged above the light-shielding sample chamber, and is arranged around the photomultiplier tube and forms an angle with the photomultiplier tube. A narrow-band filter, a long-wave pass filter, a focusing lens and a collimating lens are sequentially arranged at the front end of the photomultiplier tube. The light source includes a lamp bead, a first laser diode and a second laser diode. Light source focusing lenses are respectively arranged at the front ends of the lamp bead, the first laser diode and the second laser diode. The light source driving module includes an operational amplifier, a linear voltage regulator, a MOS tube driver and a MOS tube; a 16-bit digital / analog converter, an operational amplifier, a linear voltage regulator and a laser diode are connected in sequence, a universal input / output interface, a MOS tube driver, a MOS tube and a laser diode are connected in sequence, and the laser diode includes a first laser diode and a second laser diode; the 16-bit digital / analog converter of the main control module outputs an amplitude-adjustable voltage through the operational amplifier, and the linear voltage regulator is voltage-regulated to realize dynamic control of the excitation light intensity; the GPIO port of the main control module outputs a pulse signal to control the MOS tube driver and the switch circuit composed of the MOS tube to drive the excitation light source to generate a variable light pulse signal; The signal detection module includes a dual-channel analog switch, a scattered light signal detection channel and a fluorescence dynamics signal detection channel; the scattered light signal detection channel includes an operational amplifier and an integral amplifier; the fluorescence dynamics signal detection channel includes a USB communication circuit, an FPGA circuit, a fluorescence 16-bit digital / analog converter, and a fluorescence preamplifier; the 16-bit analog / digital converter, the operational amplifier, the integral amplifier and the dual-channel analog switch are connected in sequence; the UART communication interface, the USB communication circuit, the FPGA circuit, the fluorescence 16-bit digital / analog converter, the fluorescence preamplifier and the dual-channel analog switch are connected in sequence; the dual-channel analog switch is connected to a photomultiplier tube; The main control module includes a Cortex-M8 processor, a 16-bit digital / analog converter, a 16-bit analog / digital converter, a universal input and output interface and a UART communication interface to realize light source control and signal detection module data collection.

2. The device for correcting turbidity of photosynthetic activity of phytoplankton according to claim 1, characterized in that: The lamp bead is a 750nm LED lamp bead, the first laser diode is a 445nm laser diode, the second laser diode is a 632nm laser diode, the long-wave pass filter is a 670nm long-wave pass filter, and the narrow-band filter is a 685nm narrow-band filter.

3. The device for correcting turbidity of photosynthetic activity of phytoplankton according to claim 1, characterized in that: The angle between the lamp bead, the first laser diode, the second laser diode and the photomultiplier tube is 45 degrees; the lamp bead, the first laser diode and the second laser diode are arranged at equal intervals along the circumferential direction; the power of the first laser diode is 1.6W, and the power of the second laser diode is 1.2W.

4. The device for correcting turbidity of photosynthetic activity of phytoplankton according to claim 1, characterized in that: The light-shielding sample chamber is made of black nylon, with an opening at the top and a hollow periphery at the bottom.

5. The device for correcting turbidity of photosynthetic activity of phytoplankton according to claim 1, characterized in that: The long-wave pass filter is a HB670 material filter, and the narrow-band filter is a BP685 interference filter.

6. A method for correcting turbidity of photosynthetic activity of phytoplankton, characterized in that: The steps include: Step 1: Collect water samples with different spatial distributions in the study area. The water samples with the same spatial distribution are divided into an experimental group and a control group. The experimental group is the original water sample containing water turbidity information, and the control group is the water sample that does not contain or contains a small amount of water turbidity information after sedimentation, stratification and filtration enrichment treatment; Step 2: Use the device to measure the turbidity scattering information of the experimental group at 750nm and construct a scattering matrix; Step 3: Use the device to measure the single-turnover fluorescence kinetic curves of the experimental group and the control group, perform maximum value normalization on the fluorescence kinetic curves, obtain the initial fluorescence by fitting and inversion, and construct the initial fluorescence relative increment matrix; Step 4: Input the scattering matrix and the relative increment matrix into the correlation coefficient model to calculate the correlation coefficient; Step 5: Input the correlation coefficient into the photosynthetic activity turbidity correction model to correct the effect of water turbidity scattering on the photosynthetic activity of phytoplankton.

7. A method for correcting turbidity of phytoplankton photosynthetic activity according to claim 6, characterized in that: The scattering matrix is ​​Turb=[t1,…t i …,t N ], where Turb is the scattering matrix, t i is the scattering of experimental group i, and N is the total number of experimental groups.

8. A method for correcting turbidity of phytoplankton photosynthetic activity according to claim 6, characterized in that: The initial fluorescence relative increment matrix is: , where ΔF0 is the initial fluorescence relative increment matrix, is the initial fluorescence of experimental group i, is the initial fluorescence of control group i.

9. A method for correcting turbidity of phytoplankton photosynthetic activity according to claim 6, characterized in that: The correlation coefficient model is A=[a1 … a i … a N ] T =ΔF0·Turb T ·(Turb·Turb T ) -1 , where A is the correlation coefficient matrix, a i is the correlation coefficient between the experimental group i and the control group i.

10. A method for correcting turbidity of phytoplankton photosynthetic activity according to claim 6, characterized in that: The photosynthetic activity turbidity correction model is F V / F M =1-F'0 / F M ·(1-α·Turb), where F V / F M is the photosynthetic activity after turbidity correction, F'0 is the initial fluorescence before turbidity correction, F M is the maximum fluorescence.

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