CN107884465B - An online monitoring system and method for early warning of red tide - Google Patents

Abstract

The invention discloses an online monitoring system and method for early warning of red tide, wherein the system comprises a sampling tube, a filter, a solution distribution system, a detection pool, a ferro-manganese detection electrode, an integrated circuit and a power supply; the solution distribution system comprises a six-position valve, a pure water bottle, a mercury plating liquid bottle, an iron standard liquid bottle, a manganese standard liquid bottle, a quantitative ring and an injection pump; a solution distribution system is constructed by using a syringe pump, a quantitative ring, a six-position valve and the like to reduce the dead volume of a pipeline, a ferro-manganese detection electrode consisting of a working electrode, a reference electrode and a counter electrode is used as a detection method by combining a differential pulse stripping voltammetry, and the ferro-manganese ion concentration value serving as a red tide induction factor in seawater is obtained by a standard addition method, so that the blind spot of the initial stage existing in the current red tide online monitoring is solved, and early warning information of red tide can be provided for a monitoring department.

Description

An online monitoring system and method for early warning of red tide

Technical field

The invention relates to the technical field of marine red tide early warning, and specifically relates to an online red tide early warning online monitoring system and method based on iron and manganese ion detection.

Background technique

Due to the rapid development of modern industry and agriculture and the continuous growth of population, industrial and agricultural wastewater and domestic sewage are discharged into the ocean in large quantities, causing eutrophication of seawater, and the resulting red tide has become a worldwide public hazard. Red tide is an abnormal phenomenon in the marine ecosystem. Its growth and decline can be roughly divided into four stages: initiation, development, maintenance and extinction. In the initial stage of red tide, there are a certain number of red tide biological species in the sea area, and there are physical and chemical conditions suitable for the growth and reproduction of certain red tide organisms; in the development stage, the sea area has a certain number of certain red tide biological species, and the temperature, salinity, When the external environment such as light and nutrition reaches the most suitable range for its growth and proliferation, it can enter the exponential proliferation phase; the maintenance phase mainly depends on the physical stability of the water body and the richness of various nutrient salts, and when the nutrient salts are consumed in large quantities The replenishment rate and amount; the extinction stage can be caused by the loss of physical stability of the water body, the exhaustion of nutrients, or factors such as weather and tide. The extinction process of red tide is usually the most serious stage of harm to fisheries. After a large number of red tide organisms die, they will consume too much dissolved oxygen in the seawater during their decomposition process, causing an anoxic environment, destroying the normal ecological structure of the ocean, and threatening the survival of marine life. survival, causing massive death of fish, shrimp, and shellfish, and ultimately causing huge economic losses. Therefore, it is of great significance to monitor the marine environment, especially the physical and chemical parameters of seawater that affect the occurrence of red tides in the initial stage, and to achieve early warning of red tides.

At present, the methods used in online monitoring systems for red tide early warning mainly include water color remote sensing method, image analysis method, total organic carbon method, environmental parameter method, etc. (1) The water color remote sensing method uses satellite sensors to obtain sea surface water-leaving radiance and other data in the visible and infrared bands, extracts the remote sensing reflectivity of each band, and uses the model to calculate the inherent optical properties of the water body, and extracts red tide information and Scope of occurrence; (2) The image analysis method uses an image acquisition system installed on an unmanned fixed monitoring station or navigation beacon in the water to obtain image information of algae in seawater on-site, and uses image recognition software to identify the type, quantity and quality of algae in the photo. The growth status is identified and compared with the historical data in the database to achieve the purpose of early warning of red tide outbreaks; (3) The total organic carbon method collects seawater surface water samples containing planktonic microorganisms to remove inorganic sources formed by acidification. After CO ₂ is released, all the organic matter contained in the seawater is oxidized into organic-source CO ₂ , and the planktonic microbial biomass is converted based on the total organic carbon content, and an early warning is provided for red tides based on its changing trend; (4) The environmental parameter method is obtained by online monitoring of buoys The seawater environmental parameters, such as chlorophyll, dissolved oxygen and pH value, are used as red tide discriminant factors, and short-term red tide early warning is carried out based on their changing trends. Among them, (1) is a physical method, covering a wide sea area, and is suitable for identifying the occurrence range during the maintenance stage of red tide; (2) and (3) are biological methods, which can determine the plankton content in seawater during the development and maintenance stages of red tide. Monitor; (4) It is a chemical method that can provide short-term early warning for red tides based on changes in chemical parameters in seawater during the development stage of red tides.

None of the above technical means can conduct online monitoring of red tide in the initial stage. During the development, maintenance, and extinction stages of red tides, with the rapid proliferation and death of red tide organisms, a series of changes will occur in the physical properties such as temperature and water color of the seawater in the red tide area, as well as the chemical properties such as pH value, dissolved oxygen, and chlorophyll; and more It is forward-looking that in the initial stage of red tide, the concentration of iron and manganese in seawater will reach the maximum value. The trace elements iron and manganese are the inducing factors for the formation of red tide and are the key to inducing the formation of red tide. Studies have shown that in seawater without iron and manganese elements, the density of red tide biological populations will not increase even under the most suitable temperature, salinity, pH and basic nutritional conditions. To this end, the present invention is based on the real-time online detection technology of seawater iron and manganese ions, and aims to develop an online monitoring system for early warning of red tides, break through the blind spots of monitoring and early warning in the initial stage of red tides, and minimize the risk of fishery and aquaculture economic losses to the industry.

Contents of the invention

The purpose of the present invention is to provide an online monitoring system and method for early warning of red tide in view of the shortcomings of the existing technology.

The object of the present invention is achieved through the following technical solutions: an online monitoring system for early warning of red tide, which system includes a sampling tube, a filter, a solution distribution system, a detection pool, an iron-manganese detection electrode, an integrated circuit and a power supply ;

The solution distribution system includes a six-position valve, a pure water bottle, a mercury-plated liquid bottle, an iron standard liquid bottle, a manganese standard liquid bottle, a quantitative loop and a syringe pump;

The six-position valve has 7 external interfaces and 1 central interface. The central interface is located at the center of the valve. The central interface can be connected inside the valve body with any of the 6 external interfaces evenly distributed on the edge of the valve at a time; the central interface Connected to one end of the quantitative loop, 6 external interfaces are respectively connected to the sampling tube, pure water bottle, mercury-plated liquid bottle, iron standard liquid bottle, manganese standard liquid bottle and detection tank through pipelines; a filter is set on the sampling pipe;

The upper end of the syringe pump has three interfaces: left interface, upper interface, and right interface. It contains a solution chamber inside, which can be connected to any interface on the upper end at a time. The left interface is connected to the other end of the quantitative loop, and the upper interface passes through the tube. The pipe is connected to the detection pool, and the right interface is connected to the waste pipe through the pipe;

The iron-manganese detection electrode includes a reference electrode, a working electrode and a counter electrode; the ends of the three electrodes are connected to the integrated circuit through electrode wires.

Further, the sampling tube is a plastic tube made of polyetheretherketone, with an inner diameter of 0.25mm.

Further, the pore size of the filter membrane is 100 μm.

Further, the quantitative loop is an annular plastic tube made of polyether ether ketone with threaded fasteners at both ends. The internal capacity is 5 mL. When transferring seawater samples, pure water, mercury plating liquid, iron standard solution and manganese standard When the solution reaches the detection pool, the syringe pump is first used to extract the solution into the quantitative loop through the six-position valve, and then the solution in the quantitative loop is pushed to the detection pool.

Further, the solution chamber inside the syringe pump is 10 mL.

Further, the reference electrode is a silver wire electrode with a diameter of 500 μm, a silver/silver chloride electrode formed by surface electroplating of silver chloride; the working electrode is a gold wire electrode with a diameter of 100 μm; and the counter electrode is a silver wire electrode with a diameter of 500 μm. Platinum wire electrode.

Further, the system also includes a GPRS transmitter connected to the integrated circuit, through which the detection data is sent to the server of the monitoring department in real time.

Further, the iron-manganese detection electrode uses differential pulse stripping voltammetry to detect seawater samples.

A method for online monitoring of iron and manganese ions in seawater and red tide early warning based on the above system. The method includes:

(1) Electrode pretreatment: Extract the mercury plating liquid into the detection tank and immerse the iron and manganese detection electrode, deposit a mercury film on the surface of the working electrode to form a gold/mercury electrode, and then discharge the mercury plating liquid; extract pure water and conduct three tests on the detection tank The above cleaning removes residual mercury plating liquid;

(2) Seawater sample detection: Filter out impurities in seawater through a filter, and extract seawater samples to the detection pool; the iron-manganese detection electrode uses differential pulse stripping voltammetry to detect seawater samples, and record the stripping voltammetry curve;

(3) Add standard solution for detection: Extract an appropriate amount of iron and manganese standard solution from the iron standard solution bottle and manganese standard solution bottle and add it to the seawater sample, and then use the differential pulse stripping voltammetry with the same parameter conditions for detection again, and record the dissolution Voltampere curve; discharge the seawater sample from the detection pool, extract pure water to clean the detection pool more than three times, and wait for the next seawater sample detection;

(4) Data processing and sending: According to the values of the dissolution peak currents corresponding to iron and manganese ions in the two sets of stripping voltammetry curves, the concentration values of iron and manganese ions in the seawater samples are converted, and the detection data are sent to the monitoring department in real time to compare with normal The historical data of iron and manganese ions in seawater are compared. When the concentration value shows an increasing trend and exceeds the threshold, an early warning of red tide is issued.

Further, the iron and manganese detection electrode uses differential pulse stripping voltammetry to detect seawater samples, specifically: first, a constant potential is applied to the working electrode, and the iron and manganese ions are reduced to atomic states and enriched on the surface of the working electrode; secondly, To electrolytically dissolve iron and manganese atoms, that is, on the basis of applying a linearly varying DC scanning voltage to the working electrode, superimpose a small amplitude rectangular pulse potential, and record the difference in current between a certain time before each superimposed pulse and a certain time before the pulse termination. value to obtain the stripping voltammogram curve.

The technical advantages of the present invention are:

1. Use the quantitative loop in the solution distribution system as a temporary storage container for the transfer of seawater samples, pure water, mercury plating liquid, iron standard solution and manganese standard solution. Through the process of the solution entering and exiting the quantitative loop, deadlocks in the pipelines are effectively reduced. volume, improving the accuracy of solution volume quantification.

2. Through the optimized design of the pipeline structure of the solution distribution system, all solution circulation power comes from a single syringe pump, which not only ensures the uniformity of the solution transfer method, but also reduces the complexity of the entire system structure and improves the reliability of the system. sex.

3. Use the standard addition method to calculate the concentration of iron and manganese ions in seawater samples based on the two sets of stripping voltammetry curves detected before and after adding the iron and manganese standard solutions. Compared with the conventional standard curve method, this method It can overcome the matrix effect of the sample and meet the needs of online monitoring.

The beneficial effects of the present invention are that the present invention uses a syringe pump, a quantitative loop, a six-position valve, etc. to construct a solution distribution system, and uses an iron-manganese detection electrode composed of a working electrode, a reference electrode, and a counter electrode combined with differential pulse stripping voltammetry as the detection Methods: The standard addition method is used to obtain the concentration value of iron and manganese ions in seawater as a red tide inducing factor, which solves the blind spot in the current online monitoring of red tide and can provide early warning information of red tide to the monitoring department.

Description of the drawings

Figure 1 is a schematic structural diagram of an online monitoring system for early warning of red tides according to one embodiment;

In the picture, 1-sampling tube, 2-filter, 3-pure water bottle, 4-mercury-plated liquid bottle, 5-iron standard liquid bottle, 6-manganese standard liquid bottle, 7-quantitative loop, 8-six-position valve, 9-Central interface, 10-First external interface, 11-Second external interface, 12-Third external interface, 13-Fourth external interface, 14-Fifth external interface, 15-Sixth external interface, 16-Injection Pump, 17-left interface, 18-upper interface, 19-right interface, 20-solution chamber, 21-detection cell, 22-reference electrode, 23-working electrode, 24-counter electrode, 25-electrode lead, 26- GPRS transmitter, 27-integrated circuit, 28-power supply, 29-waste pipe.

Detailed ways

The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, but the scope of protection is not limited by this.

Example

This embodiment provides an online monitoring system for early warning of red tide, as shown in Figure 1, which mainly includes a sampling tube 1, a filter 2, a solution distribution system, a detection pool 21, an iron-manganese detection electrode, an integrated circuit 27 and Power supply 28. The solution distribution system includes a six-position valve 8, a pure water bottle 3, a mercury-plated liquid bottle 4, an iron standard liquid bottle 5, a manganese standard liquid bottle 6, a quantitative loop 7, and a syringe pump 16. The iron and manganese detection The electrodes include a reference electrode 22, a working electrode 23 and a counter electrode 24.

The sampling tube 1 is a plastic tube made of polyetheretherketone with an inner diameter of 0.25mm. The filter membrane pore size of filter 2 is 100 μm. The quantitative loop 7 is an annular plastic tube made of polyetheretherketone with threaded fasteners at both ends. The internal capacity is 5mL. The reference electrode 22 is a silver wire electrode with a diameter of 500 μm and is a silver/silver chloride electrode formed by electroplating silver chloride on the surface. The working electrode 23 is a gold wire electrode with a diameter of 100 μm. The counter electrode 24 is a platinum wire electrode with a diameter of 500 μm. Three The electrode ends are connected to the integrated circuit 26 through electrode wires 25 .

As shown in Figure 1, the six-position valve 8 has 7 interfaces. The central interface 9 is located at the center of the valve. It can be connected to any of the 6 external interfaces evenly distributed on the edge of the valve at a time: the first external interface 10, the second external interface 9. The interface 11, the third external interface 12, the fourth external interface 13, the fifth external interface 14, and the sixth external interface 15 are gated inside the valve body. Each interface is connected through a threaded fastener and a plastic pipe made of polyetheretherketone. connect. The central interface 9 is connected to one end of the quantitative loop 7, and the other six external interfaces are connected to the sampling tube 1, pure water bottle 3, mercury-plated liquid bottle 4, iron standard liquid bottle 5, manganese standard liquid bottle 6 and the detection tank through pipelines. twenty one. There are 3 interfaces at the upper end of the syringe pump 16, which contains a solution chamber 20 with a capacity of 10 mL. It can be connected to any interface at the upper end at a time. The left interface 17 is connected to the other end of the quantitative loop 7, and the upper interface 18 passes through the pipeline. Connected to the detection pool 21, the right interface 19 is connected to the waste liquid port 20 through a pipeline.

The working process is divided into four steps: electrode pretreatment, seawater sample detection, standard solution addition detection, and data processing and sending.

The working process of electrode pretreatment is as follows: adjust the internal passage of the six-position valve 8, select the central interface 9 and the second external interface 11, select the upper left interface 17 of the syringe pump 16, and extract 0.05 from the mercury plating liquid bottle 4 by the syringe pump 16 The 0.1 mol/L mercury nitrate solution based on mol/L nitric acid is temporarily stored in the quantitative loop 7, and then the central interface 9 and the fifth external interface 14 are selected, and the syringe pump 16 injects the mercury plating solution in the quantitative loop 7 for detection. Pool 21 ensures that the mercury plating liquid is immersed in the iron and manganese detection electrode surface. Through the control of the integrated circuit 27, an enrichment voltage 0.1V lower than the fixed potential of the reference electrode 22 is applied to the working electrode 23 for 4 minutes. The working electrode 23 and the counter electrode 24 form a polarization loop to transmit electrons. The working electrode The following chemical reactions occur on the surface of 23:

Hg ²⁺ +2e ^- ->Hg (1)

Thus, a mercury film is deposited on the surface of the working electrode 23 to form a gold/mercury electrode for later use. The syringe pump 16 switches on the upper port 18 to draw the mercury plating liquid in the detection pool 21 into the solution chamber 20, and then switches on the right port 19 to discharge the mercury plating liquid from the waste pipe 29. After the mercury plating liquid is discharged, use ultrapure water to clean the detection tank 21 more than three times. During cleaning, adjust the internal passage of the six-position valve 8. The central interface 9 and the sixth external interface 15 are connected, and the syringe pump 16 is connected to the upper left interface 17. The syringe pump 16 extracts ultrapure water with a resistivity greater than 18 MΩ·cm from the pure water bottle 3 and temporarily stores it in the quantitative loop 7. Then the central interface 9 and the fifth external interface 14 are connected, and the syringe pump 16 transfers the ultrapure water in the quantitative loop 7 to Ultrapure water is injected into the detection pool 21 for cleaning, and after the cleaning liquid is discharged, the seawater sample can be detected.

The working process of seawater sample detection is as follows: adjust the internal passage of the six-position valve 8, select the central interface 9 and the first external interface 10, select the upper left interface 17 of the syringe pump 16, and extract the seawater sample from the sampling tube 1 by the syringe pump 16. Flow through the filter 2 with a pore size of 100 μm to remove impurities and temporarily store them in the quantitative loop 7. Then the central interface 9 and the fifth external interface 14 are connected, and the syringe pump 16 injects the seawater sample in the quantitative loop 7 for detection. Pool 21 ensures that the seawater sample is immersed in the surface of the iron-manganese detection electrode. Under the control of the integrated circuit 27, an enrichment voltage that is 1.8V lower than the fixed potential of the reference electrode 22 is first applied to the working electrode 23 for 3 minutes. The working electrode 23 and the counter electrode 24 form a polarization loop to transmit electrons. The following chemical reaction occurs on the surface of working electrode 23:

Fe ²⁺ +Hg+2e ^- ->Fe(Hg) (2)

Mn ²⁺ +Hg+2e ^- ->Mn(Hg) (3)

As a result, the iron and manganese ions are reduced to the atomic state and enriched on the surface of the working electrode 23, and then the iron and manganese atoms are electrolytically dissolved using differential pulse stripping voltammetry, that is, on the basis of applying a linearly changing DC scanning voltage on the working electrode, a small superimposed The amplitude of the rectangular pulse potential is set to -1.8V for the scan start potential, -0.05V for the scan end potential, 10mV/s for the scan speed, 0.2s for the pulse period, 0.05V for the pulse amplitude, and 0.05s for the pulse width. The following chemistry occurs on the surface of the working electrode 23 reaction:

Fe(Hg)->Fe ²⁺ +Hg+2e ^- (4)

Mn(Hg)->Mn ²⁺ +Hg+2e ^- (5)

Record the difference between the current at a certain time before each superimposed pulse and the current at a certain time before the pulse termination, and obtain the stripping voltammetry curve of seawater sample detection.

The working process of adding standard solution for detection is: first, add a certain amount of iron and manganese standard solution to the seawater sample, adjust the internal passage of the six-position valve 8, select the central interface 9 and the third external interface 12, and select the upper end of the syringe pump 16 The left interface 17 uses the syringe pump 16 to extract the iron standard liquid from the iron standard liquid bottle 5 and temporarily stores it in the quantitative loop 7. Then the central interface 9 and the fifth external interface 14 are connected, and the syringe pump 16 removes the iron standard liquid in the quantitative loop 7. The standard liquid is injected into the detection pool 21; the internal passage of the six-position valve 8 is adjusted, the central interface 9 is connected to the fourth external interface 13, the syringe pump 16 is connected to the upper left interface 17, and the syringe pump 16 extracts manganese from the manganese standard liquid bottle 6 The standard solution is temporarily stored in the quantitative loop 7, and then the central interface 9 and the fifth external interface 14 are connected, and the manganese standard solution in the quantitative loop 7 is injected into the detection cell 21 by the syringe pump 16. To the seawater sample after adding the iron and manganese standard solution, under the control of the integrated circuit 27, a enrichment voltage of 1.8V lower than the fixed potential of the reference electrode 22 is applied to the working electrode 23 for 3 minutes. It forms a polarization loop with the counter electrode 24 to transmit electrons, and chemical reactions (2) and (3) occur on the surface of the working electrode 23. The iron and manganese ions are reduced to atomic states and enriched on the surface of the working electrode 23, and then the same parameters as when detecting seawater samples are used. The conditional differential pulse stripping voltammetry electrolytically dissolves iron and manganese atoms, chemical reactions (4) and (5) occur on the surface of the working electrode 23, and the difference in current at a certain time before each superimposed pulse and a certain time before the pulse termination is recorded. , obtain the stripping voltammogram curve of seawater sample after adding iron and manganese standard solution. Finally, ultrapure water is extracted to clean the detection pool 21 three times, waiting for the next seawater sample detection.

The data processing and sending process is as follows: based on the dissolution peak current values corresponding to iron and manganese ions in the two sets of stripping voltammetry curves, convert the concentration values of iron and manganese ions in the seawater sample, and send the detection data in real time to the GPRS transmitter 26 On the server of the monitoring department, the historical data of iron and manganese ions in normal seawater are compared. When the concentration value shows an increasing trend and exceeds the threshold, an early warning of red tide is issued.

Claims (10)

1. An on-line monitoring system for early warning of red tide is characterized by comprising a sampling tube, a filter, a solution distribution system, a detection pool, a ferro-manganese detection electrode, an integrated circuit and a power supply;

the solution distribution system comprises a six-position valve, a pure water bottle, a mercury plating liquid bottle, an iron standard liquid bottle, a manganese standard liquid bottle, a quantitative ring and an injection pump;

the six-position valve is provided with 6 external interfaces and 1 central interface, the central interface is positioned at the central position of the valve, and the central interface can be gated in the valve body with any 6 external interfaces uniformly distributed at the edge of the valve at a time; the central interface is connected to one end of the quantitative ring, and the 6 external interfaces are respectively connected with the sampling tube, the pure water bottle, the mercury plating liquid bottle, the iron standard liquid bottle, the manganese standard liquid bottle and the detection tank through pipelines; a filter is arranged on the sampling tube;

the upper end of the injection pump is provided with 3 interfaces: the left interface, the upper interface and the right interface are internally provided with 1 solution cavity, the solution cavity can be gated with any one interface at the upper end at a time, the left interface is connected with the other end of the quantitative ring, the upper interface is connected to the detection tank through a pipeline, and the right interface is connected to the waste liquid pipe through a pipeline;

the ferro-manganese detection electrode comprises a reference electrode, a working electrode and a counter electrode; the three electrode tips are each connected to the integrated circuit by electrode leads.

2. The on-line monitoring system for early warning of red tide according to claim 1, wherein the sampling tube is a polyether-ether-ketone plastic tube with an inner diameter of 0.25mm.

3. The on-line monitoring system for early warning of red tide according to claim 1, wherein the pore size of the filter membrane is 100 μm.

4. The on-line monitoring system for early warning of red tide according to claim 1, wherein the quantitative ring is an annular plastic pipe made of polyether-ether-ketone material with threaded fasteners at two ends, the internal capacity is 5mL, and when transferring a seawater sample, pure water, mercury plating solution, iron standard solution and manganese standard solution to a detection tank, the solution is pumped into the quantitative ring through a six-position valve by using a syringe pump, and then the solution in the quantitative ring is pushed into the detection tank.

5. The on-line monitoring system for early warning of red tide according to claim 1, wherein the solution cavity inside the injection pump is 10mL.

6. The on-line monitoring system for early warning of red tide according to claim 1, wherein the reference electrode is a silver/silver chloride electrode formed by electroplating silver chloride on the surface of a silver wire electrode with a diameter of 500 μm; the working electrode is a gold wire electrode with the diameter of 100 mu m; the counter electrode is a platinum wire electrode with the diameter of 500 mu m.

7. The on-line monitoring system for early warning of red tide according to claim 1, further comprising a GPRS transmitter connected to the integrated circuit, through which the detection data is transmitted in real time to a server of the monitoring department.

8. The on-line monitoring system for early warning of red tides according to claim 1, wherein the ferro-manganese detection electrode detects the seawater sample by using a differential pulse stripping voltammetry.

9. A method for online monitoring of iron and manganese ions in seawater and early warning of red tide by using the system of any one of claims 1-8, comprising the steps of:

(1) Electrode pretreatment: extracting the mercury plating solution into a detection pool, immersing a ferro-manganese detection electrode, depositing a mercury film on the surface of a working electrode to form a gold/mercury electrode, and then discharging the mercury plating solution; extracting pure water to clean the detection pool for more than three times, and removing residual mercury plating solution;

(2) Detecting a seawater sample: filtering impurities in the seawater through a filter, and extracting a seawater sample to a detection pool; the ferro-manganese detection electrode detects a seawater sample by using a differential pulse stripping voltammetry, and records a stripping voltammetry curve;

(3) And (3) adding standard solution for detection: extracting a proper amount of iron and manganese standard liquid from an iron standard liquid bottle and a manganese standard liquid bottle, adding the iron and manganese standard liquid into a seawater sample, detecting again by using a differential pulse stripping voltammetry under the same parameter condition, and recording a stripping voltammetry curve; discharging the seawater sample from the detection tank, extracting pure water to clean the detection tank for more than three times, and waiting for the next detection of the seawater sample;

(4) And (3) data processing and sending: according to the values of the dissolution peak currents respectively corresponding to the iron ions and the manganese ions in the two groups of dissolution volts An Quxian, concentration values of the iron ions and the manganese ions in the sea water sample are converted, detection data are sent to a monitoring department in real time, the detection data are compared with historical data of the iron ions and the manganese ions in normal sea water, and early warning of red tide is sent when the concentration values show rising trend and exceed a threshold value.

10. The method according to claim 9, wherein the ferro-manganese detection electrode uses differential pulse stripping voltammetry to detect seawater samples, in particular: firstly, applying constant potential on a working electrode, and reducing ferro-manganese ions into atomic states to be enriched on the surface of the working electrode; and then, the ferro-manganese atoms are electrolyzed and dissolved, namely, on the basis of applying a linear-change direct-current scanning voltage on a working electrode, a rectangular pulse potential with small amplitude is superposed, and the difference value of current at a certain time before pulse superposition and a certain time before pulse termination is recorded, so that a dissolution volt-ampere curve is obtained.