Marine biochemical sensor field calibration method

Abstract

The invention discloses a field calibration method for a marine biochemical sensor, and belongs to the technical field of marine observation. The method comprises the following steps: pumping seawater into the water tank, soaking until adsorption and desorption are balanced, and pumping seawater after emptying; blowing high-purity compressed air to enable the saturation degree of dissolved oxygen to be close to 100%, putting a carrier of the integrated sensor, blowing air to ensure that the saturation degree is 100%, sealing a pipeline, opening a sealing cover, and recording measured values by each sensor. Emptying the water tank, pumping seawater, adding a set amount of standard solution, adding sodium sulfite, and uniformly mixing; blowing high-purity nitrogen until the saturation degree of dissolved oxygen is near zero, putting a carrier, blowing air to ensure that the saturation degree is zero, sealing a pipeline and a sealing cover, and recording measured values by each sensor. And carrying out continuous immersion test, checking zero drift, evaluating a calibration result, emptying the water tank, recovering the carrier, reading a measured value and processing data. According to the field calibration method for the marine biochemical sensor, the data quality can be improved, and reliable data support is provided for related fields.

Description

Technical Field

[0001] The invention belongs to the technical field of ocean observation, and in particular relates to a field calibration method for an ocean biochemical sensor. Background Art

[0002] Marine biochemical sensors are a vital component of modern ocean observation and detection technology. Marine biochemical sensors must undergo long-term sea trials before they can be put into use. On-site calibration is the only technical means to quantitatively evaluate the sea trial effect of sensors. Compared with the development of marine biochemical sensors abroad, my country's marine biochemical sensor research and development process is seriously lacking in strict sea trial verification and on-site calibration.

[0003] In this regard, Chinese Patent 202120842599.9 discloses a field calibration device for a marine chlorophyll sensor, including a terminal control computer, a deck unit, a refrigeration control unit, an outer tank body of a calibration tank, an inner tank body of a calibration tank, a heater, a rapid cooling coil, a magnetic stirrer, a magnetic stirrer, a humidity sensor, a chlorophyll sensor, a temperature sensor, and a chlorophyll solution, which realizes precise temperature control, no contact pollution, uniform spatial distribution, portable operation, and stable operation during the calibration process.

[0004] However, the field calibration device of the marine chlorophyll sensor is no different from the laboratory calibration device. Both calibrate (calibrate) a single sensor by temperature control and adding chlorophyll standard solutions of different concentrations. The drift of sensor data caused by system dark current, heat generation, humidity, transportation vibration, etc. after the sensor is assembled on a mobile or fixed platform is ignored. Therefore, it is impossible to perform system calibration on a mobile or fixed observation platform with integrated chlorophyll sensors. In addition, the patent only targets the biochemical parameter of chlorophyll, while the commonly used biochemical sensors in marine monitoring, such as nitrate and pH sensors, still lack relevant field calibration methods. Summary of the invention

[0005] In view of the deficiencies existing in the related art, the object of the present invention is to provide a field calibration method for a marine biochemical sensor to solve the problems raised in the above background technology.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] A method for on-site calibration of a marine biochemical sensor, comprising:

[0008] S1. Use angle iron to fix the water tank on the rear deck of the sea trial vessel. A sealing cover is provided on the top of the water tank. A first pipeline and a second pipeline are provided at the bottom of the water tank. Confirm that the water tank is clean. Pump the surface seawater of the ocean filtered by the spiral membrane into the water tank through the first pipeline. Soak for a set time until the water tank wall and the seawater reach adsorption and desorption equilibrium. Drain the seawater in the water tank, re-pump the surface seawater of the ocean filtered by the spiral membrane, and measure the temperature, salinity, dissolved oxygen saturation and chlorophyll content of the seawater for reference;

[0009] S2. Cover the water tank with a sealing cover, blow high-purity compressed air into the water tank through the second pipeline in a light-proof state, monitor the change of dissolved oxygen saturation until the dissolved oxygen saturation approaches 100%, open the sealing cover, quickly put the carrier integrated with the dissolved oxygen sensor, nitrate sensor, chlorophyll sensor, polycyclic aromatic hydrocarbon sensor, CDOM sensor and irradiance sensor into the water tank, completely immerse it, and cover the sealing cover;

[0010] S3, again inject high-purity compressed air into the water tank through the second pipeline to ensure that the dissolved oxygen saturation is 100%, close the first pipeline and the second pipeline, open the sealing cover, and each sensor records the measured values ​​10 times respectively;

[0011] S4, drain the seawater in the water tank, rinse the water tank until it is clean, pump the ocean surface seawater filtered by the spiral membrane into the water tank again through the first pipeline, and measure the temperature, salinity, dissolved oxygen saturation and chlorophyll content of the seawater for reference;

[0012] S5, adding high concentration sodium nitrate standard solution, 1,5-naphthalene disulfonate sodium standard solution, quinine sulfate standard solution and chlorophyll standard solution to the water tank to make the concentrations reach 40.0 μM, 20.0 μg / L, 50.0 μg / L and 5.0 μg / L respectively, and adding a set amount of sodium sulfite salt to mix evenly;

[0013] S6. Cover the sealing cover, blow high-purity nitrogen into the water tank through the second pipeline in a light-proof state, monitor the change of dissolved oxygen saturation until the dissolved oxygen saturation approaches 0%, open the sealing cover, quickly put the carrier integrated with the dissolved oxygen sensor, nitrate sensor, chlorophyll sensor, polycyclic aromatic hydrocarbon sensor, CDOM sensor and irradiance sensor into the water tank, completely immerse it, and cover the sealing cover;

[0014] S7. Blow high-purity nitrogen into the water tank again through the second pipeline to ensure that the dissolved oxygen saturation is 0%, close the first pipeline and the second pipeline, confirm that the sealing cover is in good condition, and each sensor records the measured values ​​10 times respectively;

[0015] S8. Subject the carrier integrated with each sensor to a continuous immersion test in a water tank for no more than 12 hours, check the sensor zero drift and evaluate the calibration result, then drain the seawater in the water tank, recover the carrier integrated with each sensor, read the measured value of each sensor, and perform data processing.

[0016] In some embodiments, the marine biochemical sensor field calibration method further includes step S9, performing field calibration on the pH sensor:

[0017] S91, rinse the water tank to a clean state, pump the ocean surface seawater filtered by the spiral membrane into the water tank through the first pipeline, install the pH sensor on the carrier, immerse the carrier into the water tank, and obtain the pH sensor's response electrical signal V to the hydrogen ions of the ocean surface seawater and the pH corrected by temperature and salinity. FET ;

[0018] S92. Use the iSEA-pH seawater pH field automated calibration instrument and purified m-cresol purple indicator to measure the ocean surface seawater in the water tank multiple times, take the average of the measured pH values, and then convert them to the pH at the in-situ temperature through the CO2SYSTEM. iSEA As a standard value;

[0019] S93, temperature, salinity, pH iSEA The measured data of the response electrical signal V are substituted into the calculation formula to obtain the standard reference potential k0 to realize the sea trial calibration of the pH sensor.

[0020] In some of the embodiments, a flow meter is provided in the water tank, and in step S1, step S4 and step S91, 2000 liters of ocean surface seawater filtered by spiral membrane is accurately metered and pumped into the water tank according to the display of the flow meter.

[0021] In some embodiments, the marine biochemical sensor field calibration method further includes step S10, evaluating the sensor sea trial calibration results:

[0022] S101, for the measured values ​​of each sensor in step S3 and step S7, respectively calculate the average percentage deviation and the average absolute percentage deviation to quantify the sensor calibration drift;

[0023] S102: Calculate the root mean square deviation, average deviation and unbiased root mean square deviation of the measured values ​​of each sensor in step S8 to quantify the sensor calibration effect.

[0024] In some embodiments, the marine biochemical sensor field calibration method further includes step S11, confirming that the sea trial field calibration of each sensor meets the calibration error requirement:

[0025] S111. Confirm whether the difference between the on-site measured values ​​of the dissolved oxygen sensor, nitrate sensor, chlorophyll sensor, polycyclic aromatic hydrocarbon sensor, CDOM sensor and irradiance sensor and the set calibration values ​​is greater than 20%. If so, re-adjust the sensor hardware until the difference between the on-site measured values ​​of the sensor and the set calibration values ​​is less than 20%;

[0026] S112, confirm whether the difference between the on-site measured value of the pH sensor and the set calibration value is greater than 0.05. If so, re-adjust the sensor hardware until the difference between the on-site measured value and the set calibration value is less than 0.05.

[0027] In some of the embodiments, the field calibration method for marine biochemical sensors also includes step S12, deploying each sensor that has completed the field calibration of the sea trial and met the calibration error requirements to a set sea area for measurement, recovering the sensors after the measurement is completed, repeating steps S1 to S9, and performing field calibration again, analyzing the field measurement differences of the sensors based on the data, and comparing them with the calibration differences recorded before deployment, quantitatively analyzing the measurement drift of the sensor data during deployment, and correcting the long-term monitoring data during the sensor deployment period based on the analysis results.

[0028] In some of the embodiments, step S12 further includes: forming a sensor sea trial on-site calibration report based on data obtained from the sensor sea trial on-site calibration, and archiving and preserving the report as an important document of the sensor sea trial.

[0029] In some of the embodiments, the water tank is made of black polypropylene, a clean silicone gasket is connected to the edge of the sealing cover, and the sealing cover and the water tank are connected by a snap to seal the water tank as a whole in an airtight manner.

[0030] In some of the embodiments, the carrier integrated with the sensors is a Glider underwater glider.

[0031] In some of the embodiments, the carrier integrated with each sensor is an Argo free-drifting real-time profiling float.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] 1. The field calibration method of marine biochemical sensors provided by the present invention can significantly improve the research and development standardization and deployment and use standardization of marine long-term continuous monitoring sensors, improve the accuracy and reliability of measurement data, provide high-quality continuous observation data for marine environmental monitoring, marine scientific research, etc., and provide strong technical support for the industrialization process of marine biochemical sensors and marine scientific research in my country.

[0034] 2. The marine biochemical sensor field calibration method provided by the present invention can calibrate dissolved oxygen sensors, nitrate sensors, chlorophyll sensors, polycyclic aromatic hydrocarbons sensors, CDOM sensors and irradiance sensors at the same time, which significantly improves the efficiency of sensor calibration work and sea trial field operation efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of this application. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0036] Figure 1 This is a schematic diagram of the water tank structure of an embodiment of the on-site calibration method for marine biochemical sensors of the present invention.

[0037] In the figure:

[0038] 1. Water tank; 2. First pipeline; 3. Second pipeline; 4. Angle iron; 5. Water quality multi-parameter instrument; 6. Ocean surface water; 7. Glider underwater glider; 8. Argo free-drifting real-time profiling buoy. DETAILED DESCRIPTION

[0039] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0040] In the description of the present invention, it should be understood that the terms "center", "lateral", "longitudinal", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0041] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0042] See attached Figure 1 , a schematic embodiment of the marine biochemical sensor field calibration method proposed by the present invention is given, and the marine biochemical sensor field calibration method comprises the following steps:

[0043] S1. Use angle iron 4 to fix water tank 1 on the rear deck of the sea trial vessel. A sealing cover is provided on the top of water tank 1. A first pipeline 2 and a second pipeline 3 are provided on the bottom of water tank 1. Confirm that water tank 1 is in a clean state. Pump ocean surface seawater 6 filtered by spiral membrane into water tank 1 through first pipeline 2. Soak for a set time until adsorption and desorption equilibrium is reached between the wall of water tank 1 and seawater. Drain the seawater in water tank 1. Pump ocean surface seawater 6 filtered by spiral membrane into water tank 1 again. Measure the temperature, salinity, dissolved oxygen saturation and chlorophyll content of seawater for reference. At this time, the nitrate, chlorophyll, PAHs and CDOM of seawater in water tank 1 all reach approximately 0 or low values, and the dissolved oxygen is at a high value.

[0044] S2, cover the sealing cover, blow high-purity compressed air into the water tank 1 through the second pipeline 3 in a light-proof state, monitor the change of dissolved oxygen saturation until the dissolved oxygen saturation approaches 100%, open the sealing cover, quickly put the carrier integrated with the dissolved oxygen sensor, nitrate sensor, chlorophyll sensor, polycyclic aromatic hydrocarbon sensor, CDOM sensor and irradiance sensor into the water tank 1, completely immerse it, and cover the sealing cover;

[0045] S3, high-purity compressed air is again injected into the water tank 1 through the second pipeline 3 to ensure that the dissolved oxygen saturation is 100%, the first pipeline 2 and the second pipeline 3 are closed, the sealing cover is opened, and each sensor records the measured values ​​10 times respectively; at this time, the dissolved oxygen of the seawater in the water tank 1 reaches the 100% saturation point, the irradiance reaches the maximum value, and the nitrate, chlorophyll, PAHs and CDOM all reach the low / lowest value calibration point;

[0046] S4, drain the seawater in the water tank 1, rinse the water tank 1 until it is clean, pump the ocean surface seawater 6 filtered by the spiral membrane into the water tank 1 again through the first pipeline 2, and measure the temperature, salinity, dissolved oxygen saturation and chlorophyll content of the seawater for reference;

[0047] S5, adding high concentration sodium nitrate standard solution, 1,5-naphthalene disulfonate sodium standard solution, quinine sulfate standard solution and chlorophyll standard solution (10% water acetone solution) to the water tank 1, making the concentration reach 40.0μM, 20.0μg / L, 50.0μg / L and 5.0μg / L respectively, and adding a set amount of sodium sulfite salt to mix evenly;

[0048] S6. Cover the sealing cover, blow high-purity nitrogen into the water tank 1 through the second pipeline 3 in a light-proof state, monitor the change of dissolved oxygen saturation until the dissolved oxygen saturation approaches 0%, open the sealing cover, quickly put the carrier integrated with the dissolved oxygen sensor, nitrate sensor, chlorophyll sensor, polycyclic aromatic hydrocarbon sensor, CDOM sensor and irradiance sensor into the water tank 1, completely immerse it, and cover the sealing cover;

[0049] S7, high-purity nitrogen is injected into the water tank 1 again through the second pipeline 3 to ensure that the dissolved oxygen saturation is 0, the first pipeline 2 and the second pipeline 3 are closed, and the sealing condition of the sealing cover is confirmed to be intact. Each sensor records the measured values ​​10 times respectively; at this time, the dissolved oxygen of the seawater in the water tank 1 reaches the 0% point, the irradiance reaches the minimum value, and the nitrate, chlorophyll, PAHs and CDOM all reach the highest calibration point;

[0050] S8. Subject the carrier integrated with each sensor to a continuous immersion test in the water tank 1 for no more than 12 hours, check the sensor zero drift and evaluate the calibration result, then drain the seawater in the water tank 1, recover the carrier integrated with each sensor, read the measured value of each sensor, and perform data processing.

[0051] In order to prevent the water tank 1 wall from causing baseline fluctuations to the sensor due to light refraction, scattering and reflection, in this embodiment, the material of the water tank 1 is selected to be high-quality black polypropylene. In order to ensure the sealing effect, a clean silicone gasket is connected to the edge of the sealing cover, and the sealing cover is connected to the water tank 1 by a buckle to seal the water tank 1 as a whole.

[0052] In this embodiment, the carrier integrated with each sensor is specifically a marine mobile observation platform, and the calibration method is specifically to integrate multiple types of marine biochemical sensors into the marine mobile observation platform, and then perform on-site synchronous calibration. In some embodiments, the carrier integrated with each sensor can be selected as a Glider underwater glider 7. In some embodiments, the carrier integrated with each sensor can be selected as an Argo free-drifting real-time profiling buoy 8. The Glider underwater glider 7 and the Argo free-drifting real-time profiling buoy 8 are carriers that can provide power and platforms for each sensor.

[0053] The water tank 1 can continuously pump in or out the ocean surface seawater 6 in the sea trial area. In this embodiment, a submersible pump can be selected to achieve this function. After the water tank 1 pumps in the ocean surface seawater 6, the soaking setting time is 24 hours. The front end of the first pipeline 2 is provided with a roll filter device with a pore size of 1.0μm to remove most of the particulate matter. The first pipeline 2 and the second pipeline 3 use 304 food grade stainless steel bellows. The surface of the 304 food grade stainless steel bellows is smooth and easy to clean and maintain. In addition, it has excellent corrosion resistance and high strength and hardness. It can resist the erosion of various chemical substances and is not easy to be damaged or deformed.

[0054] The water tank 1 is equipped with a water quality multi-parameter instrument 5 to monitor in real time the temperature, salinity, turbidity and other environmental data of the ocean surface seawater 6 in the water tank 1. In step S1 and step S6, the water quality multi-parameter instrument 5 is used to measure the temperature, salinity, dissolved oxygen saturation and chlorophyll content of the seawater for reference.

[0055] In step S2, high-purity compressed air is bubbled into the water tank 1 for about 20 minutes, and the bubbling time is appropriately extended according to the change of dissolved oxygen saturation monitored by the water quality multi-parameter instrument 5. In step S3, high-purity compressed air is bubbled into the water tank 1 for about 10 minutes, and the bubbling time is appropriately extended according to the change of dissolved oxygen saturation monitored by the water quality multi-parameter instrument 5.

[0056] In step S6, high-purity nitrogen is bubbled into the water tank 1 for about 20 minutes, and the bubbling time is appropriately extended according to the change of dissolved oxygen saturation monitored by the water quality multi-parameter instrument 5. In step S7, high-purity nitrogen is bubbled into the water tank 1 for about 10 minutes, and the bubbling time is appropriately extended according to the change of dissolved oxygen saturation monitored by the water quality multi-parameter instrument 5.

[0057] The sealing cover is provided with a sensor immersion window (seal), which can be used for individual sea trial calibration tests of various sensors, or for adding various standard substances. After the sealing cover is opened, the carrier with integrated sensors can be placed on the bracket and put into the water tank 1. After turning on the power switch, various parameters of seawater can be measured. By inspecting the working status of the integrated system of each sensor, the gross measurement error and obvious fault of each sensor are detected, and the measured data are calibrated on site.

[0058] In this embodiment, the marine biochemical sensor field calibration method further includes step S9, performing field calibration on the pH sensor:

[0059] S91, rinse the water tank 1 to a clean state, pump the ocean surface seawater 6 filtered by the spiral membrane into the water tank 1 through the first pipeline 2, install the pH sensor on the carrier, immerse the carrier into the water tank 1, and obtain the response electrical signal V of the pH sensor to the hydrogen ions of the ocean surface seawater and the pH corrected by temperature and salinity. FET ;

[0060] S92. Use the iSEA-pH seawater pH field automated calibration instrument and the purified m-cresol purple indicator to measure the ocean surface seawater 6 in the water tank 1 multiple times, take the average of the measured pH values, and then convert them to the pH at the in-situ temperature through the CO2SYSTEM. iSEA As a standard value;

[0061] S93, temperature, salinity, pH iSEASubstitute the measured data such as the response electrical signal V into the calculation formula to obtain the standard reference potential k0 to realize the sea trial calibration of the pH sensor.

[0062] Among them, pH FET pH is the pH value obtained by the pH sensor, pH iSEA The pH value obtained by the designated instrument, CO2SYSTEM is a tool for calculating seawater properties related to the marine carbonate system, with Excel version and Python version. FET and pH iSEA If the error is less than 10% and the pH range is within 6.5-9.0, the pH sensor does not need to be calibrated, that is, the reference potential of the pH sensor itself is not changed.

[0063] The length, width and height of the water tank 1 are 2×1×1 meters. A flow meter is provided in the water tank 1. Specifically, the flow meter is provided at the inlet of the water tank 1. The flow meter is a precision liquid flow meter with an accuracy of ±1.0 liter. In steps S1, S4 and S91, 2000 liters of ocean surface seawater 6 filtered by a spiral membrane is accurately metered and pumped into the water tank 1 according to the display of the flow meter.

[0064] In order to evaluate the sea trial calibration results of each sensor, the data should be analyzed by appropriate mathematical statistics methods to obtain the calibration conclusion. In this embodiment, the marine biochemical sensor field calibration method also includes step S10, evaluating the sensor sea trial calibration results:

[0065] S101, for the measured values ​​of each sensor in step S3 and step S7, respectively calculate the average percentage deviation and the average absolute percentage deviation to quantify the sensor calibration drift;

[0066] S102: Calculate the root mean square deviation, average deviation and unbiased root mean square deviation of the measured values ​​of each sensor in step S8 to quantify the sensor calibration effect.

[0067] The quantitative evaluation indicators of the sea trial calibration of each sensor are shown in Table 1.

[0068] Table 1

[0069]

[0070] In Table 1, x i and i They represent the standard values ​​of high and low calibration points and the reading values ​​of the self-developed sensor respectively, and n represents the number of data points.

[0071] The marine biochemical sensor field calibration method further includes step S11, confirming that the sea trial field calibration of each sensor meets the calibration error requirement:

[0072] S111. Confirm whether the difference between the on-site measured values ​​of the dissolved oxygen sensor, nitrate sensor, chlorophyll sensor, polycyclic aromatic hydrocarbon sensor, CDOM sensor and irradiance sensor and the set calibration values ​​is greater than 20%. If so, re-adjust the sensor hardware until the difference between the on-site measured values ​​of the sensor and the set calibration values ​​is less than 20%;

[0073] S112, confirm whether the difference between the on-site measured value of the pH sensor and the set calibration value is greater than 0.05. If so, re-adjust the sensor hardware until the difference between the on-site measured value and the set calibration value is less than 0.05.

[0074] The field calibration method for marine biochemical sensors also includes step S12, deploying each sensor that has completed the field calibration of the sea trial and met the calibration error requirements to a set sea area for measurement, recovering it after the measurement is completed, repeating steps S1 to S9, and performing field calibration again, analyzing the field measurement differences of the sensors based on data, and comparing them with the calibration differences recorded before deployment, quantitatively analyzing the measurement drift (linear drift or nonlinear drift) of the sensor data during deployment, and correcting the long-term monitoring data during the sensor deployment period based on the analysis results.

[0075] Step S12 also includes: forming a sensor sea trial on-site calibration report based on the data obtained from the sensor sea trial on-site calibration, and archiving and preserving it as an important document of the sensor sea trial.

[0076] In the above-mentioned exemplary embodiment, the on-site calibration method of marine biochemical sensors can improve the accuracy and reliability of sensor measurement data, provide a precise basis for marine environmental monitoring, scientific research, etc., help to timely grasp water quality changes, protect the ecological environment, and provide strong support for the rational use of resources and the formulation of relevant policies.

[0077] The following is an explanation of the principle and method of on-site calibration of a sensor according to an embodiment of the on-site calibration method of a marine biochemical sensor of the present invention:

[0078] The dissolved oxygen sensor is calibrated on-site using the two-point method. The dissolved oxygen saturation is set to 100% by compressed air bubbling, and the dissolved oxygen saturation is set to 0% by high-purity nitrogen bubbling while adding an excess of high-grade pure sodium sulfite (2 g / 2000 L) to achieve a two-point calibration.

[0079] The nitrate sensor adopts two-point on-site calibration. The default nitrate of the ocean surface seawater 6 is 0.0μM. A certain amount of high-concentration nitrate standard solution is added to the water tank 1 and mixed evenly to make its concentration reach 40.0μM (the average nitrate concentration value at a depth of 1000 meters in the ocean) to achieve two-point calibration.

[0080] The chlorophyll sensor is calibrated on-site using the two-point method. The default chlorophyll content in the ocean surface seawater 6 filtered by the spiral membrane is 0.0 μg / L. A certain amount of high-concentration chlorophyll standard solution is added to the water tank 1 and mixed evenly to make the concentration reach 5.0 μg / L, thereby achieving two-point calibration.

[0081] The PAH sensor is calibrated on-site using the two-point method. The PAH content in the ocean surface seawater 6 filtered by the spiral membrane is set to 0.0 μg / L by default. A certain amount of high-concentration standard solution of sodium 1,5-naphthalene disulfonate is added to the water tank 1 and mixed evenly to achieve a concentration of 20.0 μg / L, thereby achieving a two-point calibration.

[0082] The CDOM sensor is calibrated on-site using the two-point method, by adding a certain amount of high-concentration quinine sulfate standard solution to the water tank 1 and mixing it evenly to make its concentration reach 50.0 μg / L, and realizing two-point calibration together with the ocean surface seawater 6; or, if the ship allows, 2000 liters of 1000-meter layer seawater is sampled multiple times through the shipboard CTD as the CDOM sensor 0 point, and a certain amount of high-concentration quinine sulfate standard solution is added to make the concentration reach 50.0 μg / L to realize two-point calibration.

[0083] The pH sensor is calibrated on-site by comparative measurement, that is, it is measured by a high-precision pH meter carried on board, and the difference between the two is the calibration value.

[0084] The irradiance sensor is calibrated on-site using the two-point method, with the zero point being the case when sealed and protected from light, and the 100% point being the case when open for exposure.

[0085] Finally, it should be noted that: the various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0086] The above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, ordinary technicians in the field should understand that the specific implementation methods of the present invention can still be modified or some technical features can be replaced by equivalents without departing from the spirit of the technical solution of the present invention, which should be included in the scope of the technical solution for protection of the present invention.

Claims

1. A method for on-site calibration of a marine biochemical sensor, characterized in that: include: S1. Use angle iron to fix the water tank on the rear deck of the sea trial vessel. A sealing cover is provided on the top of the water tank. A first pipeline and a second pipeline are provided at the bottom of the water tank. Confirm that the water tank is clean. Pump the surface seawater of the ocean filtered by the spiral membrane into the water tank through the first pipeline. Soak for a set time until the water tank wall and the seawater reach adsorption and desorption equilibrium. Drain the seawater in the water tank, re-pump the surface seawater of the ocean filtered by the spiral membrane, and measure the temperature, salinity, dissolved oxygen saturation and chlorophyll content of the seawater for reference; S2. Cover the water tank with a sealing cover, blow high-purity compressed air into the water tank through the second pipeline in a light-proof state, monitor the change of dissolved oxygen saturation until the dissolved oxygen saturation approaches 100%, open the sealing cover, quickly put the carrier integrated with the dissolved oxygen sensor, nitrate sensor, chlorophyll sensor, polycyclic aromatic hydrocarbon sensor, CDOM sensor and irradiance sensor into the water tank, completely immerse it, and cover the sealing cover; S3, again inject high-purity compressed air into the water tank through the second pipeline to ensure that the dissolved oxygen saturation is 100%, close the first pipeline and the second pipeline, open the sealing cover, and each sensor records the measured values ​​10 times respectively; S4, drain the seawater in the water tank, rinse the water tank until it is clean, pump the ocean surface seawater filtered by the spiral membrane into the water tank again through the first pipeline, and measure the temperature, salinity, dissolved oxygen saturation and chlorophyll content of the seawater for reference; S5, adding high concentration sodium nitrate standard solution, 1,5-naphthalene disulfonate sodium standard solution, quinine sulfate standard solution and chlorophyll standard solution to the water tank to make the concentrations reach 40.0 μM, 20.0 μg / L, 50.0 μg / L and 5.0 μg / L respectively, and adding a set amount of sodium sulfite salt to mix evenly; S6. Cover the sealing cover, blow high-purity nitrogen into the water tank through the second pipeline in a light-proof state, monitor the change of dissolved oxygen saturation until the dissolved oxygen saturation approaches 0%, open the sealing cover, quickly put the carrier integrated with the dissolved oxygen sensor, nitrate sensor, chlorophyll sensor, polycyclic aromatic hydrocarbon sensor, CDOM sensor and irradiance sensor into the water tank, completely immerse it, and cover the sealing cover; S7. Blow high-purity nitrogen into the water tank again through the second pipeline to ensure that the dissolved oxygen saturation is 0%, close the first pipeline and the second pipeline, confirm that the sealing cover is in good condition, and each sensor records the measured values ​​10 times respectively; S8. Subject the carrier integrated with each sensor to a continuous immersion test in a water tank for no more than 12 hours, check the sensor zero drift and evaluate the calibration result, then drain the seawater in the water tank, recover the carrier integrated with each sensor, read the measured value of each sensor, and perform data processing.

2. The marine biochemical sensor field calibration method according to claim 1, characterized in that: The step S9 is also included to calibrate the pH sensor on site: S91, rinse the water tank to a clean state, pump the ocean surface seawater filtered by the spiral membrane into the water tank through the first pipeline, install the pH sensor on the carrier, immerse the carrier into the water tank, and obtain the pH sensor's response electrical signal V to the hydrogen ions of the ocean surface seawater and the pH corrected by temperature and salinity. FET ; S92. Use the iSEA-pH seawater pH field automated calibration instrument and purified m-cresol purple indicator to measure the ocean surface seawater in the water tank multiple times, take the average of the measured pH values, and then convert them to the pH at the in-situ temperature through the CO2SYSTEM. iSEA As a standard value; S93, temperature, salinity, pH iSEA The measured data of the response electrical signal V are substituted into the calculation formula to obtain the standard reference potential k0 to realize the sea trial calibration of the pH sensor.

3. The marine biochemical sensor field calibration method according to claim 2, characterized in that: A flow meter is provided in the water tank, and in steps S1, S4 and S91, 2000 liters of ocean surface seawater filtered by the spiral membrane is accurately metered and pumped into the water tank according to the display of the flow meter.

4. The marine biochemical sensor field calibration method according to claim 2, characterized in that: The step S10 is also included, evaluating the sensor sea trial calibration result: S101, for the measured values ​​of each sensor in step S3 and step S7, respectively calculate the average percentage deviation and the average absolute percentage deviation to quantify the sensor calibration drift; S102: Calculate the root mean square deviation, average deviation and unbiased root mean square deviation of the measured values ​​of each sensor in step S8 to quantify the sensor calibration effect.

5. The marine biochemical sensor field calibration method according to claim 4, characterized in that: The step S11 is also included to confirm that the sea trial on-site calibration of each sensor meets the calibration error requirements: S111. Confirm whether the difference between the on-site measured values ​​of the dissolved oxygen sensor, nitrate sensor, chlorophyll sensor, polycyclic aromatic hydrocarbon sensor, CDOM sensor and irradiance sensor and the set calibration values ​​is greater than 20%. If so, re-adjust the sensor hardware until the difference between the on-site measured values ​​of the sensor and the set calibration values ​​is less than 20%; S112, confirm whether the difference between the on-site measured value of the pH sensor and the set calibration value is greater than 0.

05. If so, re-adjust the sensor hardware until the difference between the on-site measured value and the set calibration value is less than 0.

05.

6. The marine biochemical sensor field calibration method according to claim 5, characterized in that: The method also includes step S12, deploying each sensor that has completed the on-site calibration of the sea trial and met the calibration error requirements to the set sea area for measurement, recovering them after the measurement is completed, repeating steps S1 to S9, and performing on-site calibration again. Based on the data analysis, the on-site measurement differences of the sensors are compared with the calibration differences recorded before deployment, and the measurement drift of the sensor data during the deployment is quantitatively analyzed. Based on the analysis results, the long-term monitoring data during the sensor deployment period is corrected.

7. The marine biochemical sensor field calibration method according to claim 6, characterized in that: Step S12 also includes: forming a sensor sea trial on-site calibration report based on the data obtained from the sensor sea trial on-site calibration, and archiving and preserving it as an important document of the sensor sea trial.

8. The marine biochemical sensor field calibration method according to claim 1, characterized in that: The water tank is made of black polypropylene. A clean silicone gasket is connected to the edge of the sealing cover. The sealing cover and the water tank are connected by a snap to seal the water tank as a whole.

9. The method for on-site calibration of a marine biochemical sensor according to any one of claims 1 to 8, characterized in that: The carrier integrated with various sensors is the Glider underwater glider.

10. The on-site calibration method for marine biochemical sensors according to any one of claims 1 to 8, characterized in that: The carrier integrated with various sensors is the Argo free-drifting real-time profiling float.

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