Multichannel OJIP measuring device and method for floating algae

Abstract

The invention discloses a multi-channel OJIP measuring device and method for floating algae, and belongs to the technical field of photosynthetic activity measurement of floating algae. The device comprises an excitation emission optical structure, a light source driving module, a signal detection module, a motor driving module and a main control module. Wherein the excitation end adopts an 8-waveband LED annular array, an optical path is optimized through a low-pass optical filter and a focusing lens group, and the receiving end collects fluorescence signals through a long-wave-pass optical filter, a narrow-band optical filter and a photomultiplier. The method comprises the following steps: dynamically adjusting light intensity and collecting a multi-channel OJIP curve; decomposing the initial / maximum fluorescence matrix into superposition of four types of algae fluorescence and scattering backgrounds; and inverting chlorophyll concentrations and photosynthetic activity parameters of blue algae, green algae, diatom and cryptoalgae based on a non-negative matrix factorization algorithm. Synchronous measurement of multiple types of algae is achieved, scattering interference is eliminated, the detection efficiency is improved by 50% or above, and the method is suitable for the fields of water quality monitoring, ecological research, aquaculture and the like.

Description

Technical Field

[0001] This invention relates to the field of phytoplankton photosynthetic activity measurement technology. Specifically, it relates to a multi-channel OJIP measurement device and method that can simultaneously perform chlorophyll classification, multi-channel OJIP curve detection, and photosynthetic activity measurement of different phyla in phytoplankton samples, thereby achieving efficient and accurate measurement of chlorophyll and photosynthetic activity in phytoplankton. Background Technology

[0002] As primary producers in aquatic ecosystems, phytoplankton's chlorophyll content and photosynthetic activity directly reflect their growth status and physiological metabolism, and are also closely related to the material cycle and energy flow of the aquatic ecosystem. Furthermore, in aquaculture, phytoplankton chlorophyll content and photosynthetic activity are important indicators for determining whether the aquatic environment is suitable for aquatic organism growth; in water quality monitoring, monitoring phytoplankton chlorophyll content and photosynthetic activity can help detect eutrophication and other pollution problems in water bodies in a timely manner.

[0003] The OJIP curve method is a commonly used method for measuring the photosynthetic activity of phytoplankton. This method detects the change in chlorophyll a fluorescence intensity over time when algae are excited by pulsed light after dark adaptation (i.e., the OJIP curve), and extracts parameters such as F0 (initial fluorescence) and F6 from the curve. m (Maximum fluorescence), F v / F m A series of photosynthetic activity parameters, such as the maximum photochemical efficiency of photosystem II, are used to assess the photosynthetic activity of phytoplankton.

[0004] However, most existing OJIP (On-Jin-Proof) photosynthetic activity measurement devices for phytoplankton are single-channel designs, capable of measuring only total chlorophyll and overall photosynthetic activity in water samples. When seasonal and water quality changes occur, total chlorophyll and individual overall photosynthetic activity measurements are insufficient to accurately reflect the succession of aquatic ecosystem structures. Therefore, developing an OJIP measurement device and method for phytoplankton capable of simultaneously measuring chlorophyll concentration, community distribution, and photosynthetic activity of different phyla through multiple channels has become an urgent problem to be solved in this technical field. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a multi-channel OJIP measurement device and method for phytoplankton.

[0006] The objective of this invention is achieved through the following technical solution:

[0007] In a first aspect, the present invention provides a multi-channel OJIP measurement device for phytoplankton, comprising an excitation emission optical structure, a light source driving module, a signal detection module, a motor driving module, and a main control module;

[0008] The excitation-emission optical structure includes an excitation-end LED ring array, an excitation-end low-pass filter, an excitation-end focusing lens group, a quartz sample cell, a light source detection-end focusing lens group, a light source detection-end photodiode, a receiving-end focusing lens group, a receiving-end long-pass filter, a receiving-end narrow-band filter, a receiving-end photomultiplier tube, a dark adaptation cell, a syringe pump, a circulation pump, and a stirring pump. The LED ring array consists of LEDs evenly spaced and uniformly distributed in a ring. The excitation light from the light source is filtered by the low-pass filter to remove stray light and then converged by the excitation-end focusing lens group to form a focused spot on the sample cell. The light source detection-end focusing lens is parallel to the light source, and the excitation light passes through the light source detection end... The focusing lens converges the light, which is then converted into an electrical signal by a photodiode for intensity normalization. The receiving end is perpendicular to the excitation end. Fluorescence in the sample cell is converged by the focusing lens group at the receiving end, and then passes through a long-pass filter and a narrow-band filter before being collected by the photomultiplier tube and converted into an electrical signal. The injection pump is fixed above the sample cell. During circulation, the injection pump pushes the sealed piston downward, the stirring pump works at a constant speed to ensure uniform random sampling, the circulation pump works to draw samples from the dark adaptation cell, the water sample fills the pipe and returns to the dark adaptation cell, and then the circulation pump stops working, the node is blocked, the injection pump drives the sealed piston upward, and at the same time draws the water sample into the sample cell for testing.

[0009] The light source driving module includes a digital potentiometer, a programmable current source, and a multi-channel analog switch; a 16-bit digital-to-analog converter, a digital potentiometer, a programmable current source, and an LED ring array are connected in sequence; a general-purpose input / output interface, a multi-channel analog switch, and an LED ring array are connected in sequence; the 16-bit digital-to-analog converter of the main control module adjusts the resistance value through the digital potentiometer to regulate the current output of the programmable current source, thereby achieving dynamic control of the excitation light intensity; the GPIO port of the main control module outputs pulse signals to control the selection of the multi-channel analog switch, thereby achieving switching of multiple LED light sources;

[0010] The signal detection module includes a light source detection channel and an OJIP signal detection channel; the light source detection channel includes an operational amplifier and an integrating amplifier; the OJIP signal detection channel includes a USB communication circuit, an FPGA circuit, a fluorescent 16-bit digital-to-analog converter, and a fluorescent preamplifier; the 16-bit analog-to-digital converter, operational amplifier, integrating amplifier, and light source detection end photodiode are connected in sequence; the UART communication interface, USB communication circuit, FPGA circuit, fluorescent 16-bit digital-to-analog converter, fluorescent preamplifier, and receiving end photomultiplier tube are connected in sequence.

[0011] The motor drive module includes three motor drivers. The general-purpose input / output interface, motor drivers, and injection pump / circulation pump / stirring pump are connected in sequence. The GPIO port of the main control module controls the motor enable and rotation direction through high and low level settings.

[0012] The main control module includes a Cortex-M8 processor, a 16-bit digital-to-analog converter, a general-purpose input / output interface, a UART communication interface, a touch LCD display, and peripheral circuits, realizing light source control, motor control, data acquisition, data analysis and processing of the signal detection module, and device input / output control.

[0013] Furthermore, the LED ring array is composed of eight wavelength LEDs, namely 445nm, 490nm, 510nm, 540nm, 560nm, 590nm, 625nm, and 850nm.

[0014] Furthermore, the low-pass filter is an SPF655 filter with a transmittance greater than 90%.

[0015] Furthermore, the long-pass filter is an HB670 material filter, and the narrow-band filter is a BP685 interference filter with a cutoff depth of OD6 and a full width at half maximum (FWHM) of 15nm.

[0016] Secondly, the present invention also provides a multi-channel OJIP measurement method for phytoplankton, the specific steps of which are as follows:

[0017] Step 1: Measure the fluorescence slope in the 0-100µs range, control the slope within the threshold range by matching the light intensity, obtain a suitable excitation light intensity, and simultaneously detect the light intensity matrix E of the light source by the photodiode at the light source detection end;

[0018] Step 2: Extract water samples from the dark adaptation tank, measure the single-channel OJIP curve, perform light intensity normalization, and then use fitting analysis to retrieve the initial fluorescence from the OJIP curve. and maximum fluorescence ;

[0019] Step 3: Switch channels, repeat steps 1 and 2, and obtain the initial fluorescence matrix F0 and the maximum fluorescence matrix F of the multi-channel system. m ;

[0020] Step 4: Decompose the initial fluorescence matrix F0 into a superposition of the initial fluorescence of cyanobacteria, green algae, diatoms, and cryptophytes, and the scattering background. The initial fluorescence of cyanobacteria is FA0, that of green algae is FB0, that of diatoms is FH0, that of cryptophytes is FM0, and the scattering background is T. Then, the maximum fluorescence matrix F0 is calculated. m It is decomposed into a mixture of the maximum fluorescence of cyanobacteria, green algae, diatoms, and cryptophytes, and the scattered background, among which the maximum fluorescence of cyanobacteria is FA. m Green algae maximum fluorescence FB m diatoms' maximum fluorescence FH m Cryptophytes maximum fluorescence FM m Scattering background T;

[0021] Step 5: Given the scattering background contribution rate RT in each channel, based on the 850nm scattering background T... ch8 The scattering background T was derived and calculated. The fluorescence contribution rates of pure algae of each phylum in each channel are known, with the initial fluorescence contribution rate of cyanobacteria being RA0, that of green algae being RB0, that of diatoms being RH0, that of cryptophytes being RM0, and the maximum fluorescence contribution rate of cyanobacteria being RA. m The maximum fluorescence contribution rate of green algae RB m RH maximum fluorescence contribution rate of diatoms m Cryptophytes' maximum fluorescence contribution rate RM m The initial fluorescence and maximum fluorescence of each category are transformed according to formulas 1-8, and F0 = FA0 + FB0 + FH0 + FM0 + T is transformed into R0. =F0-T, F m =FA m +FB m +FH m +FM m +T transforms into R m =F m -T;

[0022] Step 6: Apply the Non-negative Matrix Factorization (NMF) algorithm to R0 =F0-T and R m =F m -T is used for calculation to obtain and The initial fluorescence FA0 of cyanobacteria, the initial fluorescence FB0 of green algae, the initial fluorescence FH0 of diatoms, the initial fluorescence FM0 of cryptophytes, and the maximum fluorescence FA of cyanobacteria can be obtained by using formulas 1-8. m Green algae maximum fluorescence FB m diatoms' maximum fluorescence FH m Cryptophytes maximum fluorescence FM m The photosynthetic activity F of each algal phylum was calculated based on the characteristic absorption wavelengths of each phylum. v / F m ;

[0023] Step 7: Based on the initial fluorescence (maximum fluorescence) of each phylum obtained in Step 6, and combined with the fluorescence contribution rate matrix, calculate the chlorophyll concentration of each phylum.

[0024] Furthermore, the light intensity matrix of the light source E=[E ch1 ,…E chi ,…E ch8 ], where E chi Let be the light intensity of channel i.

[0025] Furthermore, the initial fluorescence matrix F0= ,in The initial fluorescence of channel i, and the maximum fluorescence matrix F m = ,in The maximum fluorescence of channel i is denoted as .

[0026] Furthermore, the initial fluorescence FA0 of the cyanobacteria = Initial fluorescence of green algae FB0= diatom initial fluorescence FH0= Cryptophyte initial fluorescence FM0= The maximum fluorescence FA of cyanobacteria m = Green algae maximum fluorescence FB m = Diatoms have the highest fluorescence. Cryptophytes maximum fluorescence FM m = .

[0027] Furthermore, the scattering contribution rate RT=[RT ch1 ,…RT chi ,…RT ch8 ], where RT chi The contribution rate of scattering to channel i, and the scattering T of channel i chi = T ch8 RT chi / RT ch8 From this, the calculation of the scattering background T and the initial fluorescence contribution rate of cyanobacteria RA0 can be derived. The initial fluorescence contribution rate of green algae RB0= diatom initial fluorescence contribution rate Initial fluorescence contribution rate of Cryptophytes Maximum fluorescence contribution rate of cyanobacteria The maximum fluorescence contribution rate of green algae Diatoms' maximum fluorescence contribution rate Cryptophytes' maximum fluorescence contribution rate .

[0028] Furthermore, formulas 1-8 are... , , , , , , , .

[0029] Furthermore, R0 = [1,1,1,1;……; , , , ;……; , , , ], =[ ] T R m =[1,1,1,1;……; , , , ;……; , , , ], =[ , , , ] T .

[0030] Beneficial effects:

[0031] 1. Enable simultaneous measurement of multiple algal species to reflect ecosystem structure.

[0032] Traditional devices can only measure total chlorophyll and overall activity, failing to reflect changes in algal communities. This invention can simultaneously measure the photosynthetic activity and chlorophyll concentration of four phyla: cyanobacteria, green algae, diatoms, and cryptophytes. It can accurately reflect the structural succession of aquatic ecosystems during seasonal or water quality changes, providing more detailed data support for ecological analysis.

[0033] 2. Improve measurement efficiency and shorten detection time.

[0034] The device employs an 8-channel LED ring array (445nm-850nm) and, in conjunction with a multi-channel analog switch, enables rapid channel switching, allowing for multi-parameter measurements without the need for multiple samplings or device replacements. Compared to single-channel devices that require sequential testing, this significantly reduces overall testing time and improves the efficiency of water sample analysis.

[0035] 3. Reduce interference and improve measurement accuracy.

[0036] Multiple optical and algorithmic designs were used to reduce error sources: First, stray light was filtered out using a low-pass filter (SPF655), a long-pass filter (HB670), and a narrow-band filter (BP685); second, the scattering background T was derived through an 850nm channel to eliminate scattering interference; third, the parameters of various categories were inverted using a non-negative matrix factorization (NMF) algorithm, and the measured values ​​were highly close to the standard values ​​(e.g., ...). Figure 5 , 6As shown in the figure, this improves data accuracy.

[0037] 4. Integrated functions, suitable for multiple scenarios.

[0038] The device integrates three core functions: chlorophyll classification, OJIP curve detection, and photosynthetic activity analysis. It also features automatic sampling and pretreatment components such as a dark adaptation tank and an injection pump, eliminating the need for additional equipment. Its applications cover a wide range of scenarios, including aquaculture (assessing water suitability), water quality monitoring (detecting eutrophication), and ecological research (analyzing material cycling), making it more versatile.

[0039] 5. The light intensity is dynamically controllable, adapting to different water sample conditions.

[0040] The light source driving module adjusts the current through a 16-bit digital-to-analog converter and a digital potentiometer to achieve dynamic control of the excitation light intensity. At the same time, by measuring the fluorescence slope from 0 to 100 μs, the light intensity is matched to the threshold range. The light intensity can be adjusted according to the fluorescence characteristics of different water samples (such as high-concentration and low-concentration algae water samples) to avoid measurement deviations caused by improper light intensity and adapt to more diverse detection environments. Attached Figure Description

[0041] Figure 1 This is a schematic diagram of a multi-channel OJIP measurement method for phytoplankton;

[0042] Figure 2 This is a top view of the measuring device of the present invention;

[0043] Figure 3 This is a front view of the measuring device of the present invention;

[0044] Figure 4 A connection diagram of the main control module, motor drive module, light source drive module and signal detection module;

[0045] Figure 5 A diagram illustrating the classification effect of photosynthetic activity of mixed algae in the laboratory;

[0046] Figure 6 A diagram illustrating the chlorophyll classification effect of mixed algae in the laboratory.

[0047] Wherein, 10 is the excitation and emission optical structure, 10a is the excitation-end LED ring array, 10b is the excitation-end low-pass filter, 10c is the excitation-end focusing lens group, 10d is the quartz sample cell, 10e is the light source detection-end focusing lens group, 10f is the light source detection-end photodiode, 10g is the receiving-end focusing lens group, 10h is the receiving-end long-pass filter, 10i is the receiving-end narrowband filter, 10j is the receiving-end photomultiplier tube, 10k is the dark adaptation cell, 10l is the injection pump, 10m is the circulation pump, and 10n is the stirring pump.

[0048] 20 is a light source driver module, 20a is a digital potentiometer, 20b is a programmable current source, and 20c is a multi-channel analog switch;

[0049] 30 is a signal detection module, 30a is an operational amplifier, 30b is an integrating amplifier, 30c is a USB communication circuit, 30d is an FPGA circuit, 30e is a fluorescent 16-bit digital-to-analog converter, and 30f is a fluorescent preamplifier.

[0050] 40 is a motor drive module, 40a is the first motor driver, 40b is the second motor driver, and 40c is the third motor driver;

[0051] 50 is the main control module. Detailed Implementation

[0052] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. However, the following embodiments are only for explaining the present invention, and the scope of protection of the present invention should include all the contents of the claims. Moreover, through the description of the following embodiments, those skilled in the art can fully implement all the contents of the claims of the present invention.

[0053] Example:

[0054] like Figure 1 As shown, a multi-channel OJIP measurement method for phytoplankton includes the following steps:

[0055] Step 1: Measure the fluorescence slope in the 0-100µs range, control the slope within the threshold range by matching the light intensity, obtain a suitable excitation light intensity, and simultaneously detect the light intensity matrix E of the light source by the photodiode at the light source detection end;

[0056] Step 2: Extract water samples from the dark adaptation tank, measure the single-channel OJIP curve, perform light intensity normalization, and then use fitting analysis to retrieve the initial fluorescence from the OJIP curve. and maximum fluorescence ;

[0057] Step 3: Switch channels, repeat steps 1 and 2, and obtain the initial fluorescence matrix F0 and the maximum fluorescence matrix F of the multi-channel system. m ;

[0058] Step 4: Decompose the initial fluorescence matrix F0 into a superposition of the initial fluorescence of cyanobacteria, green algae, diatoms, and cryptophytes, and the scattering background. The initial fluorescence of cyanobacteria is FA0, that of green algae is FB0, that of diatoms is FH0, that of cryptophytes is FM0, and the scattering background is T. Then, the maximum fluorescence matrix F0 is calculated. m It is decomposed into a mixture of the maximum fluorescence of cyanobacteria, green algae, diatoms, and cryptophytes, and the scattered background, among which the maximum fluorescence of cyanobacteria is FA. m Green algae maximum fluorescence FB mdiatoms' maximum fluorescence FH m Cryptophytes maximum fluorescence FM m Scattering background T;

[0059] Step 5: Given the scattering background contribution rate RT in each channel, based on the 850nm scattering background T... ch8 The scattering background T was derived and calculated. The fluorescence contribution rates of pure algae of each phylum in each channel are known, with the initial fluorescence contribution rate of cyanobacteria being RA0, that of green algae being RB0, that of diatoms being RH0, that of cryptophytes being RM0, and the maximum fluorescence contribution rate of cyanobacteria being RA. m The maximum fluorescence contribution rate of green algae RB m RH maximum fluorescence contribution rate of diatoms m Cryptophytes' maximum fluorescence contribution rate RM m The initial fluorescence and maximum fluorescence of each category are transformed according to formulas 1-8, and F0 = FA0 + FB0 + FH0 + FM0 + T is transformed into R0. =F0-T, F m =FA m +FB m +FH m +FM m +T transforms into R m =F m -T;

[0060] Step 6: Apply the Non-negative Matrix Factorization (NMF) algorithm to R0 =F0-T and R m =F m -T is used for calculation to obtain and The initial fluorescence FA0 of cyanobacteria, the initial fluorescence FB0 of green algae, the initial fluorescence FH0 of diatoms, the initial fluorescence FM0 of cryptophytes, and the maximum fluorescence FA of cyanobacteria can be obtained by using formulas 1-8. m Green algae maximum fluorescence FB m diatoms' maximum fluorescence FH m Cryptophytes maximum fluorescence FM m The photosynthetic activity F of each algal phylum was calculated based on the characteristic absorption wavelengths of each phylum. v / F m ;

[0061] Step 7: Based on the initial fluorescence (maximum fluorescence) of each phylum obtained in Step 6, and combined with the fluorescence contribution rate matrix, calculate the chlorophyll concentration of each phylum.

[0062] like Figures 2-4As shown, a multi-channel OJIP measurement device for phytoplankton includes an excitation-emission optical structure 10, a light source driving module 20, a signal detection module 30, a motor driving module 40, and a main control module 50. The excitation-emission optical structure 10 includes an excitation-end LED ring array 10a, an excitation-end low-pass filter 10b, an excitation-end focusing lens group 10c, a quartz sample cell 10d, a light source detection-end focusing lens group 10e, a light source detection-end photodiode 10f, a receiving-end focusing lens group 10g, a receiving-end long-pass filter 10h, a receiving-end narrow-band filter 10i, a receiving-end photomultiplier tube 10j, a dark adaptation cell 10k, an injection pump 10l, a circulation pump 10m, and a stirring pump 10n.

[0063] The light source driving module 20 includes a digital potentiometer 20a (AD5207), a programmable current source 20b (LT3092), and a multiplex analog switch 20c.

[0064] The signal detection module 30 includes an operational amplifier 30a (THS4031), an integrating amplifier 30b (IVC102), a USB communication circuit 30c, an FPGA circuit 30d, a fluorescence 16-bit digital-to-analog converter 30e (ADS8330), and a fluorescence preamplifier 30f (OPA656).

[0065] The motor drive module 40 consists of three motor drivers DRV8825 (first motor driver 40a, second motor driver 40b and third motor driver 40c) and peripheral circuits.

[0066] The main control module 50 is based on a Cortex-M8 processor and combines a 16-bit digital-to-analog converter, a 16-bit analog-to-digital converter, a general-purpose input / output interface, a UART communication interface, a touch LCD display, and peripheral circuits to realize light source control, signal detection module data acquisition, data analysis and processing, and device input / output control.

[0067] Specifically, the results of multi-channel OJIP measurements of phytoplankton are as follows:

[0068] Stock solutions were prepared from laboratory-cultured Microcystis aeruginosa, Chlorella vulgaris, Cyclocystis simulans, and Cryptophyta. Photosynthetic activity and chlorophyll concentration at characteristic absorption wavelengths were measured. The stock solutions were then diluted at specific ratios to obtain mixed samples. Figure 2-4 The multi-channel OJIP measurement device for phytoplankton algae is according to Figure 1 The multi-channel OJIP method for phytoplankton was shown to measure chlorophyll concentration and photosynthetic activity of each phylum in the mixed sample. The results are as follows: Figure 5-6 As shown, the measured results of chlorophyll concentration and photosynthetic activity of each category in the mixed sample are close to the actual results.

[0069] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A multi-channel OJIP measurement device for phytoplankton, characterized in that, include: The excitation-emission optical structure (10) includes an excitation-end LED ring array (10a), an excitation-end low-pass filter (10b), an excitation-end focusing lens group (10c), a quartz sample cell (10d), a light source detection end focusing lens group (10e), a light source detection end photodiode (10f), a receiving end focusing lens group (10g), a receiving end long-pass filter (10h), a receiving end narrow-band filter (10i), a receiving end photomultiplier tube (10j), a dark adaptation cell (10k), an injection pump (10l), a circulation pump (10m), and a stirring pump (10n). The light source driving module (20) includes a digital potentiometer (20a), a programmable current source (20b), and a multi-channel analog switch (20c) for dynamically adjusting the LED light intensity and switching between multiple channels; The signal detection module (30) includes a light source detection channel and an OJIP signal detection channel, which are respectively connected to the photodiode (10f) at the light source detection end and the photomultiplier tube (10j) at the receiving end. The motor drive module (40) includes three motor drivers that drive the injection pump (10l), circulation pump (10m), and stirring pump (10n) respectively. The main control module (50) integrates a processor, analog-to-digital / digital-to-analog converter, communication interface and peripheral circuits, and is used to coordinate the operation of each module and data processing.

2. The apparatus according to claim 1, characterized in that, The excitation end LED ring array (10a) consists of LEDs in eight bands: 445nm, 490nm, 510nm, 540nm, 560nm, 590nm, 625nm, and 850nm, arranged in an equally spaced ring.

3. The apparatus according to claim 1, characterized in that, The excitation end low-pass filter (10b) is an SPF655 filter, the receiving end long-pass filter (10h) is an HB670 filter, and the receiving end narrowband filter (10i) is a BP685 interference filter.

4. The apparatus according to claim 1, characterized in that, The light source driving module (20) adjusts the resistance value of the digital potentiometer (20a) through a 16-bit digital-to-analog converter, controls the output current of the programmable current source (20b), and realizes dynamic control of the excitation light intensity; and selects different LED channels through a multi-channel analog switch (20c).

5. A multi-channel OJIP measurement method for phytoplankton, characterized in that, Includes the following steps: Step 1: Measure the fluorescence slope in the 0-100μs range, adjust the light intensity to the threshold range, and simultaneously detect the light intensity matrix E of the light source; Step 2: Extract water samples from the dark adaptation tank, measure the single-channel OJIP curve, and obtain the initial fluorescence after normalization by light intensity fitting. and maximum fluorescence ; Step 3: Switch channels and repeat steps 1-2 to obtain the initial fluorescence matrix F0 and the maximum fluorescence matrix F of the multi-channel system. m ; Step 4: Set F0 and F m It is decomposed into the superposition of the initial / maximum fluorescence and the scattering background T of cyanobacteria, green algae, diatoms, and cryptophytes; Step 5: Based on the 850nm channel scattering background T ch8 The total scattering background T is derived from the scattering contribution rate RT; the fluorescence matrix is ​​converted into a system of linear equations by combining the fluorescence contribution rate matrices of each category. Step 6: Solve for the initial fluorescence FA0 / FB0 / FH0 / FM0 and the maximum fluorescence FA for each category using the non-negative matrix factorization algorithm. m / FB m / FH m / FM m Calculate the photosynthetic activity F of each category v / F m ; Step 7: Calculate the chlorophyll concentration of each phylum based on the fluorescence contribution rate matrix.

6. The method according to claim 5, characterized in that, The system of linear equations mentioned in step 5 is as follows: =F0-T; R m =F m -T; Where R0 / R m The fluorescence contribution rate matrix, / These are the fluorescence vectors for each category in the baseline channel.

7. The method according to claim 5, characterized in that, The photosynthetic activity F mentioned in step 6 v / F m According to formula F v / F m =(F m -F0) / F m Calculate and correlate with the characteristic absorption wavelengths of each category.

8. A classification system for photosynthetic activity of phytoplankton, characterized in that, It includes the apparatus according to any one of claims 1-4, and a processing program for performing the method according to any one of claims 5-7.

9. The system according to claim 8, characterized in that, The system output data includes chlorophyll concentration and photosynthetic activity parameters of cyanobacteria, green algae, diatoms, and cryptophytes.

10. A computer-readable storage medium, characterized in that, It contains a computer program that, when executed, implements the multi-channel OJIP measurement method for phytoplankton as described in any one of claims 5-7.

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