Method for in situ calibration of marine biochemical sensors

Abstract

The application discloses a kind of marine biochemical sensor field calibration methods, belong to marine observation technical field.The method is: pumping seawater to water tank, soaking to adsorption and desorption equilibrium, emptying after pumping seawater again;High-purity compressed air is blown into to make dissolved oxygen saturation near 100%, put into the carrier of integrated sensor, blow to ensure that saturation is 100%, close pipeline, open sealed cover, each sensor records measured value.Empty water tank and pump seawater again, add set amount of standard solution, add sodium sulfite and mix evenly;High-purity nitrogen is blown into to make dissolved oxygen saturation near zero, put into the carrier, blow to ensure that saturation is zero, close pipeline and sealed cover, each sensor records measured value again.Continuous immersion test is carried out, zero drift is checked, calibration result is evaluated, water tank is emptied, carrier is recycled and measured value is read, and data is processed.The marine biochemical sensor field calibration method provided by the application can improve data quality and provide reliable data support for related fields.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of ocean observation, and particularly relates to a field calibration method for an ocean biochemical sensor. BACKGROUND

[0002] The ocean biochemical sensor is a crucial component in modern ocean observation and detection technology. Before being put into application, the ocean biochemical sensor must undergo long-term sea trial verification, and field calibration during sea trial is the only technical means for quantitatively evaluating the sea trial effect of the sensor.

[0003] To this end, Chinese patent 202120842599.9 discloses a field calibration device for an ocean chlorophyll sensor, which comprises a terminal control computer, a deck unit, a refrigeration control unit, a calibration tank outer tank body, a calibration tank inner tank body, a heater, a rapid cooling coil, a magnetic stirring rod, a magnetic stirrer, a humidity sensor, a chlorophyll sensor, a temperature sensor, and a chlorophyll solution. The device realizes precise temperature control, non-contact pollution, uniform spatial distribution, portable operation, and stable operation during the calibration process.

[0004] However, the field calibration device for the ocean chlorophyll sensor has no difference from the laboratory calibration device, and both of them calibrate (calibrate) a single sensor by temperature control and adding chlorophyll standard solutions with different concentrations, ignoring the data drift of the sensor caused by system dark current, heat generation, humidity, transportation vibration, etc. after the sensor is assembled to a mobile or fixed platform. Therefore, the field calibration device cannot calibrate the mobile or fixed observation platform integrated with the chlorophyll sensor. In addition, the patent is only directed to the biochemical parameter of chlorophyll, and there is still a lack of related field calibration methods for commonly used biochemical sensors such as nitrate and pH sensors in ocean monitoring. SUMMARY

[0005] In view of the deficiencies in the related art, the present application aims to provide a field calibration method for an ocean biochemical sensor to solve the problems raised in the background art.

[0006] To achieve the above-mentioned purpose, the present application provides the following technical solutions:

[0007] A field calibration method for an ocean biochemical sensor, comprising:

[0008] S1, fixing a water tank on the rear deck of a sea trial ship using an angle iron, the water tank being provided with a sealing cover at the top and a first pipeline and a second pipeline at the bottom, confirming that the water tank is in a clean state, pumping the large ocean surface seawater filtered by a roll-type membrane into the water tank through the first pipeline, soaking for a set time until the water tank wall and the seawater reach adsorption and desorption equilibrium, emptying the seawater in the water tank, re-pumping the large ocean surface seawater filtered by the roll-type membrane, and measuring the temperature, salinity, dissolved oxygen saturation, and chlorophyll content of the seawater for reference use;

[0009] S2, cover the sealing cover, and blow high-purity compressed air into the water tank through the second pipeline in the light-proof state, monitor the change of dissolved oxygen saturation, until the dissolved oxygen saturation tends to 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, cover the sealing cover;

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

[0011] S4, empty the seawater in the water tank, flush the water tank to a clean state, pump the large ocean surface seawater filtered by the roll film into the water tank through the first pipeline again, and measure the temperature, salinity, dissolved oxygen saturation and chlorophyll content of the seawater for reference;

[0012] S5, add high-concentration sodium nitrate standard solution, 1, 5-naphthalene disulfonic acid 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 add a certain amount of sodium sulfite and mix uniformly;

[0013] S6, cover the sealing cover, and blow high-purity nitrogen into the water tank through the second pipeline in the light-proof state, monitor the change of dissolved oxygen saturation, until the dissolved oxygen saturation tends to 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, cover the sealing cover;

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

[0015] S8, the carrier integrated with the sensors is continuously immersed in the water tank for no more than 12 hours, the sensor zero drift is tested and the calibration result is evaluated, then the seawater in the water tank is emptied, the carrier integrated with the sensors is recovered, the measurement values of each sensor are read, and data processing is performed.

[0016] In some embodiments, the marine biochemical sensor field calibration method further comprises step S9, field calibration of the pH sensor:

[0017] S91, flush the water tank to clean, pump the large ocean surface water filtered by the roll membrane into the water tank through the first pipeline, install the pH sensor on the carrier, immerse the carrier into the water tank, obtain the response electric signal V of the pH sensor to the hydrogen ion of the large ocean surface water and the pH corrected by the temperature and salinity FET ;

[0018] S92, use the iSEA-pH seawater pH field automatic calibration instrument and the purified m-cresol purple indicator to measure the large ocean surface water in the water tank for multiple times, average the measured pH values, and then convert the pH at the in-situ temperature by the CO2 SYSTEM iSEA as a reference value;

[0019] S93, put the measured data of the temperature, salinity, pH iSEA and the response electric signal V into the calculation formula, obtain the standard reference potential k0, and realize the sea trial calibration of the pH sensor.

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

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

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

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

[0024] In some embodiments, the marine biochemical sensor field calibration method further comprises step S11, confirming whether the field measured values of each sensor meet the calibration error requirements:

[0025] S111, confirm whether the field measured values of the dissolved oxygen sensor, the nitrate sensor, the chlorophyll sensor, the polycyclic aromatic hydrocarbon sensor, the CDOM sensor and the irradiance sensor are greater than 20% different from the set calibration values, if yes, then re-adjust the sensor hardware until the field measured values of the sensors are less than 20% different from the set calibration values;

[0026] S112, confirm whether the field measured values of the pH sensor are greater than 0.05 different from the set calibration values, if yes, then re-adjust the sensor hardware until the field measured values are less than 0.05 different from the set calibration values.

[0027] In some embodiments, the marine biochemical sensor field calibration method further comprises the step S12 of deploying the sensors that have completed the sea trial field calibration and met the calibration error requirements to the set sea area for measurement work, recovering after completing the measurement work, repeating the steps S1 to S9, performing field calibration again, comparing the sensor field measurement differences according to data analysis with the calibration differences recorded before the deployment, quantitatively analyzing the measurement drift of the sensor data during the deployment, and correcting the long-term monitoring data of the sensors during the deployment according to the analysis results.

[0028] In some embodiments, the step S12 further comprises forming a sensor sea trial field calibration report based on the data obtained by the sensor sea trial field calibration, and archiving the report as an important document of the sensor sea trial.

[0029] In some embodiments, the material of the water tank is black polypropylene, a clean silica gel gasket is connected to the edge of the sealing cover, and the sealing cover is connected with the water tank through buckling to seal the water tank as a whole.

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

[0031] In some embodiments, the carrier integrated with the sensors is an Argo free-drifting real-time profile float.

[0032] Compared with the prior art, the beneficial effects of the present application are:

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

[0034] 2. The marine biochemical sensor field calibration method provided by the present application can simultaneously calibrate the dissolved oxygen sensor, the nitrate sensor, the chlorophyll sensor, the polycyclic aromatic hydrocarbon sensor, the CDOM sensor and the irradiance sensor, and significantly improve the sensor calibration work efficiency and the sea trial field operation efficiency. DETAILED DESCRIPTION

[0035] The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this application, illustrate embodiments of the application and serve to explain the principles of the application. In the drawings:

[0036] Figure 1The water tank structure diagram of one embodiment of the marine biochemical sensor field calibration method.

[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 seawater; 7, glider underwater glider; 8, Argo free-drifting real-time profile float. DETAILED DESCRIPTION

[0039] The technical solutions in the embodiments will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0040] In the description of the present application, it should be understood that the terms "center", "transverse", "longitudinal", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the purpose of facilitating the description of the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation of the present application.

[0041] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connecting" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be directly connected, or indirectly connected through an intermediate medium; it can be the communication between the two elements inside. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0042] Referring to the accompanying Figure 1 , an illustrative embodiment of the marine biochemical sensor field calibration method proposed by the present application is given, which includes the following steps:

[0043] S1, the water tank 1 is fixed on the back deck of the sea trial ship using angle iron 4, the water tank 1 top is provided with a sealing cover, the water tank 1 bottom is provided with a first pipeline 2 and a second pipeline 3, confirm the water tank 1 is clean, pump the large ocean surface seawater 6 filtered by the roll type membrane into the water tank 1 through the first pipeline 2, soak for a set time, until the water tank 1 wall and seawater reach adsorption and desorption balance, empty the seawater in the water tank 1, pump the large ocean surface seawater 6 filtered by the roll type membrane into the water tank 1 again, measure the seawater temperature, salinity, dissolved oxygen saturation and chlorophyll content for reference; At this time, the seawater in the water tank 1 reaches approximately 0 or low value of nitrate, chlorophyll, PAHs and CDOM, 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 the light-proof state, monitor the dissolved oxygen saturation change, until the dissolved oxygen saturation tends to 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, cover the sealing cover;

[0045] S3, blow high-purity compressed air into the water tank 1 through the second pipeline 3 again, ensure that the dissolved oxygen saturation is 100%, close the first pipeline 2 and the second pipeline 3, open the sealing cover, and each sensor records 10 measurement values respectively; At this time, the seawater in the water tank 1 reaches 100% saturation point of dissolved oxygen, reaches the highest value of irradiance, and reaches the low / lowest value calibration point of nitrate, chlorophyll, PAHs and CDOM;

[0046] S4, empty the seawater in the water tank 1, flush the water tank 1 to the clean state, pump the large ocean surface seawater 6 filtered by the roll type membrane into the water tank 1 through the first pipeline 2 again, and measure the seawater temperature, salinity, dissolved oxygen saturation and chlorophyll content for reference;

[0047] S5, add high-concentration sodium nitrate standard solution, 1,5-naphthalene disulfonic acid sodium standard solution, quinine sulfate standard solution and chlorophyll standard solution (10% water acetone solution) into the water tank 1, so that the concentrations reach 40.0 μM, 20.0 μg / L, 50.0 μg / L and 5.0 μg / L respectively, and a certain amount of sodium sulfite salt is added and mixed uniformly;

[0048] S6, cover the sealing cover, blow high-purity nitrogen into the water tank 1 through the second pipeline 3 in the light-proof state, monitor the dissolved oxygen saturation change, until the dissolved oxygen saturation tends to 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, cover the sealing cover;

[0049] S7, high-purity nitrogen gas is again introduced into the water tank 1 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 good, and each sensor records 10 measurement values; at this time, the dissolved oxygen in the seawater in the water tank 1 reaches 0%, the irradiance reaches a minimum value, and the nitrate, chlorophyll, PAHs and CDOM all reach the highest calibration point;

[0050] S8, the carrier integrated with the sensors is subjected to a water tank 1 continuous immersion test for no more than 12 hours to verify the sensor zero drift and evaluate the calibration results, then the seawater in the water tank 1 is emptied, the carrier integrated with the sensors is recovered, the measurement values of each sensor are read, and data processing is performed.

[0051] In order to avoid the baseline fluctuation of the sensors caused by the light refraction, scattering and reflection of the tank wall of the water tank 1, in the 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 with the water tank 1 through buckling to seal the water tank 1 as a whole.

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

[0053] The water tank 1 can continuously pump in or pump out the ocean surface seawater 6 in the test area, and in the embodiment, a submersible pump can be selected to realize this function. The soaking time of the water tank 1 after pumping in the ocean surface seawater 6 is 24 hours. The front end of the first pipeline 2 is provided with a 1.0 μm pore size roll filter device to remove most of the particulate matter. The first pipeline 2 and the second pipeline 3 adopt 304 food-grade stainless steel corrugated pipes. The 304 food-grade stainless steel corrugated pipe has a smooth surface, is easy to clean and maintain, and has excellent corrosion resistance, as well as high strength and hardness, and can resist the corrosion of various chemicals and is not easy to damage and deform.

[0054] The water tank 1 is provided with a water quality multi-parameter instrument 5 to monitor the temperature, salinity, turbidity and other environmental data of the ocean surface seawater 6 in the water tank 1 in real time. In steps S1 and S6, the temperature, salinity, dissolved oxygen saturation and chlorophyll content of the seawater are measured by using the water quality multi-parameter instrument 5 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 the dissolved oxygen saturation degree 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 the dissolved oxygen saturation degree monitored by the water quality multi-parameter instrument 5.

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

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

[0058] In this embodiment, the marine biochemical sensor field calibration method further comprises step S9 of calibrating the pH sensor on site:

[0059] S91, flush the water tank 1 to a clean state, pump the deep ocean surface seawater 6 filtered by the roll film into the water tank 1 through the first pipeline 2, install the pH sensor on the carrier, and immerse the carrier into the water tank 1 to obtain the response electric signal V of the pH sensor to the hydrogen ion of the deep ocean surface seawater and the pH FET corrected by temperature and salinity;

[0060] S92, use the iSEA-pH seawater pH field automatic calibration instrument and purified m-cresol purple indicator to measure the deep ocean surface seawater 6 in the water tank 1 multiple times, average the measured pH value, and then convert the pH iSEA at the in-situ temperature to the standard reference potential k0 as a value;

[0061] S93, substitute the measured data such as temperature, salinity, pH iSEA , and response electric signal V into the calculation formula to obtain the standard reference potential k0, so as to realize the sea test correction of the pH sensor.

[0062] Wherein, pH FET is the pH value obtained by the pH sensor, and pH iSEACO2SYSTEM is a tool for calculating seawater properties related to the marine carbonate system, which has excel version, and python version, etc. If the pH value obtained by the designated instrument is less than 10% error, and the pH range is within 6.5-9.0, the pH sensor does not need to be corrected, that is, the reference potential of the pH sensor itself is not changed. FET and the error of pH iSEA is less than 10%, and the pH range is within 6.5-9.0, the pH sensor does not need to be corrected, 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 2x1x1m, and a flow meter is arranged in the water tank 1. Specifically, the flow meter is arranged at the inlet of the water tank 1, and the flow meter is selected as a precision liquid flow meter with an accuracy of ±1.0L. In steps S1, S4 and S91, 2000L of the ocean surface seawater 6 after the rolling membrane filtration is accurately metered and pumped into the water tank 1 according to the flow meter display.

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

[0065] S101, the measured values of each sensor in steps S3 and S7 are calculated to obtain the average percentage deviation and the average absolute percentage deviation, respectively, to quantify the calibration drift of the sensor;

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

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

[0068] Table 1

[0069]

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

[0071] The field calibration method of the marine biochemical sensor further includes step S11 of confirming whether the calibration error of each sensor in the sea trial field reaches the calibration error requirement:

[0072] S111, confirming whether the difference between the measured values of the dissolved oxygen sensor, the nitrate sensor, the chlorophyll sensor, the polycyclic aromatic hydrocarbon sensor, the CDOM sensor and the irradiance sensor and the set calibration values is greater than 20%, if yes, then the sensor hardware is debugged again until the difference between the measured values of the sensor and the set calibration values is less than 20%;

[0073] S112, confirming whether the difference between the in-situ measured value of the pH sensor and the set calibration value is greater than 0.05, if yes, re-adjusting the sensor hardware until the difference between the in-situ measured value and the set calibration value is less than 0.05.

[0074] The in-situ calibration method of the marine biochemical sensor further comprises a step S12 of deploying each sensor that has completed the in-situ calibration of the sea trial and meets the calibration error requirement to a set sea area for measurement work, recovering after completing the measurement work, repeating the steps S1 to S9, performing in-situ calibration again, comparing the in-situ measured difference of the sensor according to data analysis with the calibration difference 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 of the sensor during deployment according to the analysis result.

[0075] The step S12 further comprises forming a sensor sea trial in-situ calibration report based on the data obtained by the in-situ calibration of the sensor sea trial, and archiving the report as an important document of the sensor sea trial.

[0076] In the above exemplary embodiment, the in-situ calibration method of the marine biochemical sensor can improve the accuracy and reliability of the measurement data of the sensor, provide accurate basis for marine environment monitoring, scientific research, etc., and help to timely grasp the water quality changes and protect the ecological environment.

[0077] The in-situ calibration principle method of the sensor of one embodiment of the in-situ calibration method of the marine biochemical sensor of the application will be described below:

[0078] The dissolved oxygen sensor adopts two-point in-situ calibration, the dissolved oxygen saturation is 100% by compressed air bubbling method, the dissolved oxygen saturation is 0% by high-purity nitrogen bubbling method, and excess high-purity sodium sulfite (2g / 2000L) is added at the same time to realize two-point calibration.

[0079] The nitrate sensor adopts two-point in-situ calibration, the nitrate in the ocean surface water 6 is 0.0 μM by default, a certain amount of high-concentration nitrate standard solution is added to the water tank 1 to mix uniformly, so that the concentration reaches 40.0 μM (the average concentration value of nitrate at the depth of 1000 meters in the ocean), and two-point calibration is realized.

[0080] The chlorophyll sensor adopts two-point in-situ calibration, the chlorophyll content in the ocean surface water 6 filtered by the roll-type membrane is 0.0 μg / L by default, a certain amount of high-concentration chlorophyll standard solution is added to the water tank 1 to mix uniformly, so that the concentration reaches 5.0 μg / L, and two-point calibration is realized.

[0081] The polycyclic aromatic hydrocarbon sensor adopts two-point field calibration, and the polycyclic aromatic hydrocarbon content in the large ocean surface seawater 6 filtered by the roll type membrane is 0.0 μg / L by default. A certain amount of 1,5-naphthalene disulfonic acid sodium high concentration standard solution is added to the water tank 1 to mix uniformly, so that the concentration reaches 20.0 μg / L, and two-point calibration is realized.

[0082] The CDOM sensor adopts two-point field calibration. A certain amount of high-concentration quinine sulfate standard solution is added to the water tank 1 to mix uniformly, so that the concentration reaches 50.0 μg / L, and two-point calibration is realized with the ocean surface seawater 6. Alternatively, 1000 meters of seawater 2000 liters are taken by the shipborne CTD multiple times, as the CDOM sensor 0 point, a certain amount of high-concentration quinine sulfate standard solution is added to mix uniformly, so that the concentration reaches 50.0 μg / L, and two-point calibration is realized.

[0083] The pH sensor is calibrated by comparison in the field, that is, it is measured by a high-precision pH meter carried on the ship, and the difference between the two is the calibration value.

[0084] The irradiance sensor adopts two-point field calibration. The zero point is sealed from light, and the 100% exposure condition is opened.

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

[0086] The above embodiments are only used to illustrate the technical solutions of the present application and not to limit it. Although the present application has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the specific embodiments of the present application can be modified or some technical features can be replaced by equivalent ones without departing from the spirit of the present application. They should all be included in the technical solution range of the present application.

Claims

1. A method for on-site calibration of a marine biochemical sensor, characterized in that, include: S1. Secure the water tank to the aft deck of the sea trial vessel using angle iron. The top of the water tank is equipped with a sealing cap, and the bottom of the water tank is equipped with a first pipeline and a second pipeline. Confirm that the water tank is clean. Pump ocean surface seawater filtered by a spiral membrane into the water tank through the first pipeline and soak it for a set time until the water tank wall and the seawater reach an adsorption and desorption equilibrium. Drain the seawater from the water tank and pump ocean surface seawater filtered by a spiral membrane back in. Measure the temperature, salinity, dissolved oxygen saturation, and chlorophyll content of the seawater for reference. S2. Cover with the sealing cap, and in the dark, blow high-purity compressed air into the water tank through the second pipeline to monitor the change in dissolved oxygen saturation until the dissolved oxygen saturation approaches 100%. Open the sealing cap and quickly place the carrier integrating 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 with the sealing cap. S3. High-purity compressed air is blown into the water tank again through the second pipeline to ensure that the dissolved oxygen saturation is 100%. The first and second pipelines are closed, the sealing cover is opened, and each sensor records 10 measurement values. S4. Drain the seawater from the tank, rinse the tank until it is clean, and pump ocean surface seawater filtered by the spiral membrane back into the tank through the first pipeline. Measure the temperature, salinity, dissolved oxygen saturation and chlorophyll content of the seawater for reference. S5. Add high-concentration sodium nitrate standard solution, sodium 1,5-naphthalenedisulfonate standard solution, quinine sulfate standard solution and chlorophyll standard solution to the water tank to achieve concentrations of 40.0 μM, 20.0 μg / L, 50.0 μg / L and 5.0 μg / L respectively, and add the set amount of sodium sulfite salt and mix well. S6. Cover with the sealing cap, and in the dark, blow high-purity nitrogen into the water tank through the second pipeline to monitor the change in dissolved oxygen saturation until the dissolved oxygen saturation approaches 0%. Open the sealing cap and quickly put the carrier integrating 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 with the sealing cap. S7. High-purity nitrogen gas is blew into the water tank again through the second pipeline to ensure that the dissolved oxygen saturation is 0%. The first and second pipelines are sealed, and the sealing cap is confirmed to be in good condition. Each sensor records 10 measurement values. S8. Conduct a continuous immersion test in a water tank for no more than 12 hours on the carrier integrating each sensor to check the zero-point drift of the sensor and evaluate the calibration results. Then, drain the seawater in the water tank, recover the carrier integrating each sensor, read the measured values ​​of each sensor, and perform data processing.

2. The method for on-site calibration of marine biochemical sensors according to claim 1, characterized in that, It also includes step S9, which involves on-site calibration of the pH sensor: S91. Rinse the water tank until clean. Pump ocean surface seawater filtered by a spiral wound membrane into the water tank through the first pipeline. Install the pH sensor on the carrier and immerse it in the water tank along with the carrier. Obtain the electrical signal V of the pH sensor's response to hydrogen ions in the ocean surface seawater and the pH value corrected for temperature and salinity. FET ; S92. Using the iSEA-pH seawater pH in-situ automated calibration instrument and purified m-cresol purple indicator, the surface ocean seawater in the tank was measured multiple times. The measured pH values ​​were averaged and then converted to pH at in-situ temperature using 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, so as to realize the sea trial calibration of the pH sensor.

3. The method for on-site calibration of marine biochemical sensors according to claim 2, characterized in that, A flow meter is installed in the water tank. In steps S1, S4 and S91, 2000 liters of ocean surface seawater filtered by spiral wound membrane is accurately pumped into the water tank according to the flow meter display.

4. The method for on-site calibration of marine biochemical sensors according to claim 2, characterized in that, It also includes step S10, evaluating the sensor sea trial calibration results: S101. For the measured values ​​of each sensor in steps S3 and S7, calculate the average percentage deviation and the average absolute percentage deviation respectively to quantify the sensor calibration drift. S102. For the measured values ​​of each sensor in step S8, calculate the root mean square deviation, average deviation, and unbiased root mean square deviation to quantify the sensor calibration effect.

5. The method for on-site calibration of marine biochemical sensors according to claim 4, characterized in that, It also includes step S11, confirming that the on-site calibration of each sensor during sea trials meets the calibration error requirements: S111. Confirm whether the difference between the field measurement 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, readjust the sensor hardware until the difference between the field measurement values ​​of the sensors and the set calibration values ​​is less than 20%. S112. Confirm whether the difference between the on-site measured value and the set calibration value of the pH sensor is greater than 0.

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

05.

6. The method for on-site calibration of marine biochemical sensors according to claim 5, characterized in that, The method also includes step S12, in which each sensor that has completed the on-site calibration of the sea trial and met the calibration error requirements is deployed to the designated sea area for measurement. After the measurement is completed, the sensor is retrieved and steps S1 to S9 are repeated to perform on-site calibration again. The differences in the on-site measurements of the sensors are analyzed based on the data and compared with the calibration differences recorded before deployment. The measurement drift of the sensor data during deployment is quantitatively analyzed, and the long-term monitoring data of the sensors during deployment is corrected based on the analysis results.

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

8. The method for on-site calibration of marine biochemical sensors according to claim 1, characterized in that, The water tank is made of black polypropylene. The edge of the sealing cap is connected with a clean silicone gasket. The sealing cap and the water tank are connected by a snap-fit ​​to ensure an airtight seal.

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

10. The method for on-site calibration of marine biochemical sensors according to any one of claims 1-8, characterized in that, The carrier integrating various sensors is the Argo free-drift real-time profile buoy.

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