CN115046979A

CN115046979A - Polycyclic aromatic hydrocarbon ocean in-situ monitor, monitoring method and application thereof

Info

Publication number: CN115046979A
Application number: CN202210305316.6A
Authority: CN
Inventors: 马君; 王杰; 程凯; 赵航; 赵璐; 商祥年; 黄阳玉; 史晓凤
Original assignee: Ocean University of China
Current assignee: Ocean University of China
Priority date: 2022-03-25
Filing date: 2022-03-25
Publication date: 2022-09-13

Abstract

The invention belongs to the technical field of marine pollution in-situ monitoring, and discloses a polycyclic aromatic hydrocarbon marine in-situ monitor, a monitoring method and application thereof. The monitoring method comprises the following steps: the underwater monitoring cabin quantitatively acquires a seawater sample in situ, mixes the seawater sample with a colloidal sol enhanced substrate in a flowing cuvette, and excites a spectral signal of the seawater sample through a laser beam focused in the cuvette; transmitting the surface enhanced raman spectral data to an aquatic terminal; and (3) identifying the Raman characteristic peak of the polycyclic aromatic hydrocarbon in the surface enhanced Raman spectrum of the seawater sample to obtain pollution data of the polycyclic aromatic hydrocarbon in the seawater. The sampling precision of the sampling and mixing mechanism of the invention reaches +/-10 mu L, the sampling relative error is less than 0.5 percent, and the requirement of surface enhanced Raman spectrum detection is met; the invention has the lowest detection concentration of the polycyclic aromatic hydrocarbon as low as 2 multiplied by 10 ^‑9 The mol/L can effectively monitor polycyclic aromatic hydrocarbon pollutants in the seawater; the maximum power of the device of the invention is only 80W,is green and environment-friendly.

Description

Polycyclic aromatic hydrocarbon ocean in-situ monitor, monitoring method and application thereof

Technical Field

The invention belongs to the technical field of marine pollution in-situ monitoring, and particularly relates to a polycyclic aromatic hydrocarbon marine in-situ monitor, a monitoring method and application thereof.

Background

After the 21 st century, a series of marine environmental pollution problems are brought while huge economic benefits are brought by the development of marine resources. The polycyclic aromatic hydrocarbon is a high-toxicity persistent organic pollutant, has a long half-life period, has the hazards of carcinogenicity, mutagenicity, teratogenicity and the like, and is the carcinogen which is firstly discovered by human beings and is most in quantity. The main sources of polycyclic aromatic hydrocarbon pollution in the ocean are atmospheric sedimentation, surface runoff, oil leakage, waste disposal, production and domestic sewage discharge and the like. As polycyclic aromatic hydrocarbon can cause harm to the ecological environment of offshore areas in China, and the offshore areas are closely related to the lives of residents in coastal zones, an in-situ, rapid and efficient monitoring means for polycyclic aromatic hydrocarbon in seawater is established, and the monitoring and the treatment of the environmental pollution of the offshore areas are particularly important.

At present, the laboratory detection methods for polycyclic aromatic hydrocarbons mainly comprise fluorescence spectroscopy, Gas Chromatography (GC), High Performance Liquid Chromatography (HPLC), infrared spectroscopy, color/mass spectrometry (GC-MS) and the like, and the methods have the advantages of high sensitivity, high resolution and high specificity. The method is not suitable for field determination of polycyclic aromatic hydrocarbon in seawater due to the defects of high instrument price, complex sample pretreatment process, long detection period, large instrument volume, difficult field implementation and the like, and the complicated sample pretreatment process can cause volatilization of part of low-ring-number polycyclic aromatic hydrocarbon, so that the inaccuracy of an experimental result is caused.

In addition, the polycyclic aromatic hydrocarbon in seawater or marine sediments can be rapidly detected by a biomarker detection method of mullet goby cytochrome P4502K3 genes, multi-drug resistance genes l or phosphatidic acid phosphatase genes, but the detection method is still away from the automatic and in-situ monitoring of the polycyclic aromatic hydrocarbon in the seawater for a certain distance. The surface enhanced Raman scattering technology is one of ideal means for future ocean exploration due to the characteristics of abundant information content (capable of identifying the types of polycyclic aromatic hydrocarbons), no need of sample pretreatment, simple and convenient operation, high accuracy and the like.

Through the above analysis, the problems and defects of the prior art are as follows:

(1) the laboratory detection method for polycyclic aromatic hydrocarbons mainly comprises fluorescence spectroscopy, Gas Chromatography (GC), High Performance Liquid Chromatography (HPLC), infrared spectroscopy, color/mass spectrometry (GC-MS) and the like, which are mainstream polycyclic aromatic hydrocarbon detection methods at present and have the advantages of high sensitivity, high resolution and high specificity, but the methods are not suitable for field measurement of polycyclic aromatic hydrocarbons in seawater due to the defects of high instrument price, complex sample pretreatment process, long detection period, large instrument volume, difficult field application and the like, and the complex sample pretreatment process can cause volatilization of part of polycyclic aromatic hydrocarbons with low ring number, so that the experimental result deviation is caused.

(2) In the prior art, mullet goby cytochrome P4502K3 gene, multi-drug resistance gene l or phosphatidic acid phosphatase gene are used as biomarkers, and the methods for detecting polycyclic aromatic hydrocarbon in seawater or marine sediments are not mature in automatic and in-situ schemes.

Disclosure of Invention

In order to overcome the problem that the detection method in the related technology is difficult to realize in-situ, rapid and automatic monitoring of polycyclic aromatic hydrocarbon pollutants in seawater, the disclosed embodiment of the invention provides a polycyclic aromatic hydrocarbon ocean in-situ monitor, a monitoring method and application thereof.

The technical scheme is as follows: a polycyclic aromatic hydrocarbon ocean in-situ monitor comprises: the underwater monitoring cabin mixes the collected seawater sample and the gold sol enhanced substrate in the flowing cuvette, focuses laser into the flowing cuvette, and simultaneously excites a surface enhanced Raman scattering optical signal of the seawater sample; collecting the surface enhanced Raman scattering spectrum of the seawater sample, and transmitting the surface enhanced Raman spectrum data to the overwater terminal; the overwater terminal obtains pollution data of the polycyclic aromatic hydrocarbon in the seawater by identifying the Raman characteristic peak of the polycyclic aromatic hydrocarbon in the surface enhanced Raman spectrum of the seawater sample.

Specifically, the polycyclic aromatic hydrocarbon ocean in-situ monitor comprises an overwater terminal and an underwater monitoring cabin, wherein the overwater terminal supplies power to the underwater monitoring cabin through an 8-core watertight network cable and controls communication. The overwater terminal is positioned on the deck, comprises an upper computer and a direct-current power supply and is used for controlling the underwater monitoring cabin in real time; the underwater monitoring cabin is used for responding to an instruction of an overwater terminal, collecting a seawater sample, injecting the seawater sample and the gold sol enhanced substrate into a flowing cuvette for mixing, exciting and collecting a surface enhanced Raman spectrum of the seawater sample, and integrating a spectrum detection mechanism, a sampling and mixing mechanism and a hardware control module in the underwater monitoring cabin to realize corresponding functions.

The spectrum detection mechanism consists of a spectrometer, a laser and a Raman preposed light path and is used for realizing the collection function of the surface enhanced Raman scattering spectrum of the seawater sample. The spectrometer is a device for converting a surface enhanced Raman scattering optical signal of a seawater sample into an electric signal; the laser may emit a 785nm laser beam; the Raman front-end light path can expand, collimate and filter a laser beam emitted by the laser and then converge the laser beam into the flowing cuvette (to excite the surface enhanced Raman scattering optical signal of the seawater sample), and can also collect the surface enhanced Raman scattering optical signal of the seawater sample, filter the surface enhanced Raman scattering optical signal and guide the surface enhanced Raman scattering optical signal into the spectrometer.

The sampling and mixing mechanism consists of a peristaltic pump, a switching valve, an electromagnetic valve, a filter, a gold sol reinforced substrate storage bin, a waste liquid storage bin, an air pressure balance bottle, a throttle valve, an external thread through joint and a flow cuvette, wherein a flow pipeline of a reagent consists of a stainless steel clamping sleeve and a Teflon pipe, and the sampling and mixing mechanism is used for collecting seawater samples, mixing the seawater samples and the gold sol reinforced substrate into the flow cuvette (realizing an adsorption reinforcing effect), discharging mixed waste liquid in the flow cuvette and cleaning the flow cuvette. The peristaltic pump is a stepping motor micro peristaltic pump, can provide the power of transporting fluid, and in the invention, the sample introduction volume of the reagent is controlled by controlling the rotation steps of the peristaltic pump; the switching valve is a six-channel switching valve, which is provided with a public channel and six sub-channels, wherein a lower end interface (a sample inlet interface) of the flow cuvette is connected with the public channel of the switching valve, a seawater sample channel, an air channel in a cabin, a gold sol enhanced substrate channel and a waste discharge channel are respectively connected with the sub-channels of the switching valve, and different reagents can be transported into the flow cuvette or mixed waste liquid of the flow cuvette can be discharged by switching the connection of the public channel and the sub-channels; the electromagnetic valve is a normally closed miniature electromagnetic valve, the seawater sampling channel can be opened by electrifying the electromagnetic valve, and the seawater sampling channel is electrified and controlled by the singlechip main controller so as to control the opening and closing of the seawater sampling channel; the throttle valve is used for mechanically adjusting the flow of seawater sampling, so that the seawater flow is uniform, and the sampling volume is convenient to control; the air pressure balance bottle is internally provided with an elastic bag which is connected with an upper end port (an exhaust interface) of the flowing cuvette through a hose, when a reagent is injected into the flowing cuvette, air in the cuvette is passively exhausted into the air pressure balance bottle, the reagent can be ensured to be smoothly injected into the cuvette, when waste liquid is exhausted, the air in the air pressure balance bottle returns to the cuvette, the waste liquid can be smoothly exhausted out of the cuvette, and the air pressure balance bottle is arranged to ensure that the reagent cannot seep out of the flowing cuvette to damage an electronic device; the filter is arranged on the outer side of the underwater monitoring hatch cover and is used for filtering impurities such as silt, suspended matters and the like in the seawater sample; the external thread straight joint is used for connecting the seawater sampling pipeline to the inner side of the underwater monitoring hatch cover, and a seawater sample firstly passes through the filter and then enters the seawater sampling pipeline through a channel reserved in the hatch cover.

The hardware control module consists of a singlechip main controller, a serial server, a stepping motor driver, a DC-DC power supply and a watertight electric joint. The single chip microcomputer main controller is used for receiving an instruction of the water terminal to control the electromagnetic valve to work and transmitting temperature and humidity data in the cabin to the water terminal in real time; the serial server is a device for converting Ethernet communication of the overwater terminal into RS232 serial communication, is provided with a plurality of RS232 serial interfaces, can meet the access of all serial devices (such as a spectrometer, a laser and the like) in the cabin, establishes a communication line between the overwater terminal upper computer and the serial devices in the cabin, and realizes the functional control of the overwater terminal on the serial devices in the cabin through the serial development of the devices; the step motor driver is an actuating mechanism which converts electric pulse into angular displacement and is used for driving the step motor to rotate by a corresponding step angle in a set direction; the DC-DC power supply provides 24V/12V/5V direct current for electrical equipment in the cabin; the watertight electric connector is an interface for connecting a watertight net cable into the underwater monitoring cabin.

Specifically, the instrument is lowered into seawater to be monitored for polycyclic aromatic hydrocarbon pollution, and power supply and communication connection is established. The upper computer sends corresponding control commands to the underwater monitoring cabin through a software interface, and all devices in the control instrument work in a matched mode, so that automatic function operation is achieved. For the sampling and mixing mechanism, when a sampling and mixing command sent by an upper computer is received, the following steps are automatically executed: the electromagnetic valve is opened, the public channel is connected with the seawater sample channel by the switching valve, the peristaltic pump rotates forwards for a certain number of steps, a quantitative seawater sample is sucked into the public channel, the electromagnetic valve is closed, the public channel is connected with the air channel in the cabin by the switching valve, the peristaltic pump rotates forwards for a certain number of steps again, the seawater sample in the public channel is transported into the flow cuvette by the air in the cabin, the public channel is connected with the gold sol reinforced substrate channel by the switching valve, the peristaltic pump rotates forwards for a certain number of steps, a quantitative gold sol reinforced substrate is sucked into the public channel, the public channel is connected with the third channel by the switching valve, the peristaltic pump rotates forwards for a certain number of steps again, the gold sol reinforced substrate in the public channel is transported into the flow cuvette by the air in the cabin, and finishing the mixing with the seawater sample, and finishing the execution of the command of 'sampling and mixing'.

For the spectrum detection mechanism, when a spectrum acquisition function sent by an upper computer is received, the following steps are automatically executed: the laser starts laser with certain power, the spectrometer collects the surface enhanced Raman spectrum of the seawater sample and transmits data to the overwater terminal, and the laser stops laser and the command of spectrum collection is executed.

After the spectrum detection is finished, the sampling and mixing mechanism receives a waste discharge command sent by an upper computer, and the following steps are automatically executed: the switching valve connects the public channel with the waste discharge channel, the peristaltic pump reversely rotates for a certain number of steps, and the mixed waste liquid is transported into the waste liquid storage bin, and the waste discharge command is executed.

For the 'cleaning' command, the sampling and mixing mechanism utilizes the close cooperation of the switching valve and the peristaltic pump to transport the seawater of the next station to be tested into the flow cuvette for cleaning, and transports the waste liquid generated by cleaning into the waste liquid storage bin. The invention can be utilized to realize the monitoring of the polycyclic aromatic hydrocarbon in the seawater by sequentially executing 3 functions of sampling and mixing, spectrum acquisition and waste discharge.

Furthermore, the underwater monitoring cabin is internally designed into an upper and lower double-layer supporting plate integrated structure, and the spectrum detection mechanism, the sampling and mixing mechanism and the hardware control module are integrated into the underwater monitoring cabin. Practice proves that the integrated structure can utilize the space in the cabin to the maximum extent and reduce the size of the underwater monitoring cabin under the condition of not influencing the functions of all parts.

Further, the spectrometer is coupled with a collecting sub-optical path of the Raman front-end optical path through an optical fiber, the laser is coupled with an exciting sub-optical path of the Raman front-end optical path through an optical fiber, the spectrometer, the laser and the Raman front-end optical path are placed in a shape like a Chinese character 'pin', the Raman front-end optical path is arranged in front, and the spectrometer and the laser are arranged at the back and are both fixed on an upper supporting plate in the sealed cabin through bolts. The communication and power supply circuit of the spectrometer and the laser are connected with the equipment hardware control module through a wire passing hole reserved in the upper supporting plate.

Furthermore, the filter adopts a stainless steel filter screen and is mainly used for filtering fine particles such as silt, suspended matters and the like in a water sample. The filter is fixed on the outer side of the front end cover through threads. The external thread straight-through joint is arranged on the inner side of the front end cover through threads and an O-shaped ring and is used for connecting the stainless steel clamping sleeve to the front end cover so as to form a pipeline for a water sample to enter the sealed cabin.

The electromagnetic valve is installed on the lower supporting plate through a bolt and is connected with one side of the ferrule interface of the external thread through connector through a stainless steel ferrule. The throttle valve is installed on the other side of the electromagnetic valve and is connected with the electromagnetic valve through a stainless steel clamping sleeve. The colloidal gold storage bin is arranged on the lower supporting plate through a U-shaped hoop and is used for storing an elastic bag filled with colloidal gold. The waste liquid storage bin is arranged on the lower supporting plate through a U-shaped hoop and is used for storing an elastic bag filled with waste liquid. The air pressure balance bottle is arranged on the upper supporting plate through a U-shaped hoop and is used for fixing the air pressure balance elastic bag, and the air pressure balance elastic bag is connected with an interface of the flowing cuvette through a Teflon tube. The switching valve is a multi-channel switching valve, and each channel of the switching valve is sequentially connected with a throttle valve, a colloidal gold storage bin, a waste liquid storage bin and an elastic bag in an air pressure balance bottle by adopting a Teflon pipe and an inverted cone connector. The switching valve is parallelly installed on the lower floor's backup pad to it is fixed through U type hoop.

And a pump pipe water inlet of the peristaltic pump is connected with a public channel of the switching valve through an inverted cone connector and a Teflon pipe, and a pump pipe water outlet is connected with a lower end interface of the flow cuvette.

The peristaltic pump is arranged on the lower supporting plate in a penetrating mode and fixed through bolts.

Furthermore, for a hardware control module of the instrument, the single-chip microcomputer main controller, the serial server and the DC-DC power supply are fixed between the supporting plate and the lower supporting plate on the sealed cabin through single-head copper columns, and communication and power supply lines of all devices are connected with a control system through via holes reserved in the supporting plate. The watertight electric connector is fixed on the outer side of the front end cover through threads and is sealed in a waterproof mode through an O-shaped ring. The single-chip microcomputer main controller is used for controlling opening and closing of the electromagnetic valve and collecting temperature and humidity data in the underwater monitoring cabin, the serial server is used for converting an Ethernet of an upper computer of the water terminal into an RS232 serial port required by a serial device in the cabin, a communication circuit for controlling the device in the underwater monitoring cabin by the upper computer is established, and the DC-DC power supply provides a 24V/12V/5V direct-current power supply for an electronic device in the cabin.

The invention also aims to provide a monitoring method of the polycyclic aromatic hydrocarbon ocean in-situ monitor, which comprises the following steps: in-situ seawater accurate sampling and quantitative adsorption enhancement of an enhanced substrate and a seawater sample are carried out by utilizing a multi-channel and automatic sampling and mixing mechanism, so that polycyclic aromatic hydrocarbon in the seawater sample generates a surface enhanced Raman scattering effect;

and carrying out in-situ monitoring on the pollution of the marine polycyclic aromatic hydrocarbon by using a sampling and mixing mechanism, a spectrum detection mechanism and a hardware control module.

The invention also aims to provide a monitoring device for monitoring the pollution of organic pollutants (persistent organic pollutants, mainly polycyclic aromatic hydrocarbons), pesticides and antibiotics in a water body (mainly ocean), wherein the monitoring device is loaded with the polycyclic aromatic hydrocarbon ocean in-situ monitor.

By combining all the technical schemes, the invention has the advantages and positive effects that:

first, aiming at the technical problems existing in the prior art and the difficulty in solving the problems, the technical problems to be solved by the technical scheme of the present invention are closely combined with results, data and the like in the research and development process, and some creative technical effects are brought after the problems are solved. The specific description is as follows:

the monitor provided by the invention consists of an overwater terminal and an underwater monitoring cabin, wherein the overwater terminal supplies power to the underwater monitoring cabin through a watertight network cable and controls communication. When the device is used, the underwater monitoring cabin is placed in seawater, a quantitative seawater sample is collected firstly under the control of an overwater terminal, the seawater sample and a gold sol enhanced substrate are mixed in a flowing cuvette (the adsorption enhancement effect is realized), then laser is converged into the flowing cuvette (a surface enhanced Raman scattering light signal of the seawater sample is excited), the surface enhanced Raman spectrum of the seawater sample is collected, finally spectral data are transmitted to the overwater terminal, and a pollution conclusion of polycyclic aromatic hydrocarbon in the seawater is obtained by identifying a polycyclic aromatic hydrocarbon Raman characteristic peak in the surface enhanced Raman spectrum of the seawater sample. The monitor has the advantages of low minimum detection concentration, high automation degree, strong in-situ performance and the like, and can monitor the pollution of polycyclic aromatic hydrocarbons in seawater.

The invention realizes the full-automatic collection of the seawater sample in situ under water and the collection of the surface enhanced Raman spectrum, and can rapidly, accurately and reliably analyze the pollution condition of the polycyclic aromatic hydrocarbon in the seawater on site;

through laboratory tests, the sampling precision of the sampling and mixing mechanism of the invention reaches +/-10 mu L, the sampling relative error is less than 0.5 percent, and the requirements of surface enhanced Raman spectrum detection are met; the lowest detection concentration of the invention is as low as 2 multiplied by 10 ^-9 mol/L (laboratory, simple substance) can effectively monitor polycyclic aromatic hydrocarbon pollutants in seawater; the maximum power is only 80W, and the method is green and environment-friendly.

The invention realizes the quantitative collection of seawater samples at different depths by changing the rotation steps of the peristaltic pump, thereby obtaining the condition of monitoring the pollution of water bodies at different depths with the depth of 0-20 meters underwater.

The invention has wide application field and flexible technical means, and can be used for detecting other pollutants in water bodies, such as pesticides, antibiotics and the like by slight modification.

The invention has simple structure, standard communication interface, convenient disassembly and installation and convenient later maintenance.

Secondly, considering the technical solution as a whole or from the perspective of products, the technical effects and advantages of the technical solution to be protected by the present invention are specifically described as follows:

the invention provides a polycyclic aromatic hydrocarbon ocean in-situ monitor based on a surface enhanced Raman scattering technology, which can realize in-situ collection of a seawater sample, excitation and collection of a surface enhanced Raman spectrum of the seawater sample, and analysis of pollution condition of polycyclic aromatic hydrocarbon in seawater by identifying a Raman characteristic peak of polycyclic aromatic hydrocarbon in the surface enhanced Raman spectrum.

Third, as inventive supplementary proof of the claims of the present invention, there are several important aspects as follows:

the expected income and commercial value after the technical scheme of the invention is converted are as follows: the technical scheme of the invention can become a commodity with complete functions through simple engineering appearance design, and has great commercial prospect for monitoring organic pollutants in offshore areas in China.

The technical scheme of the invention fills the technical blank in the industry at home and abroad: at present, no monitoring instrument and method for in-situ monitoring of polycyclic aromatic hydrocarbon organic pollutants in seawater based on a surface enhanced Raman scattering technology are reported in China, and the invention fills the blank of in-situ monitoring of polycyclic aromatic hydrocarbon based on the surface enhanced Raman scattering technology in China.

The technical scheme of the invention solves the technical problems which are always desired to be solved but are not successful: the invention designs an automatic sampling and mixing mechanism for realizing underwater in-situ monitoring of polycyclic aromatic hydrocarbon pollutants, successfully solves the technical problems of automatic in-situ seawater accurate sampling and quantitative mixing and adsorption of an enhanced substrate and a seawater sample, enables the surface enhanced Raman scattering technology to be successfully applied to underwater in-situ monitoring, and opens up a new application space for the surface enhanced Raman scattering technology.

The technical scheme of the invention overcomes the technical prejudice that: research documents show that in a period of time, domestic researchers or try to design an underwater in-situ monitoring device based on the surface enhanced Raman scattering technology, but the underwater in-situ monitoring device cannot operate; or a sensor based on the surface enhanced Raman scattering technology is built, but only a shipborne experiment is carried out, and the in-situ monitoring cannot be realized. The reason is that researchers think that the key problems (in-situ seawater accurate sampling, quantitative mixed adsorption of the enhanced substrate and the seawater sample) for realizing the surface enhanced raman scattering in-situ monitoring still need to be researched, and new technical means are needed for supporting. The invention considers that the technical problem can be realized by ingenious technical design, namely the sampling and mixing mechanism stated by the invention.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present disclosure and, together with the description, serve to explain the principles of the disclosure.

FIG. 1 is a schematic diagram of a polycyclic aromatic hydrocarbon marine in-situ monitor provided by an embodiment of the invention;

FIG. 2 is a schematic view of an upper supporting plate structure of the sealed cabin provided by the embodiment of the invention;

FIG. 3 is a schematic view of a lower supporting plate structure of the sealed cabin provided by the embodiment of the invention;

FIG. 4 is a schematic diagram of a hardware control module installation provided by an embodiment of the present invention;

FIG. 5 is a schematic view of a front end cover interface design of a capsule according to an embodiment of the present invention;

FIG. 6 is a schematic view of a flow cell provided in accordance with an embodiment of the present invention;

FIG. 7 is a front view of a flow cuvette mount provided by an embodiment of the invention;

FIG. 8 is a diagram showing the relationship between the number of steps of rotation of the peristaltic pump and the depth of water when a 1.5mL seawater sample is quantitatively collected according to an embodiment of the present invention; wherein, FIG. 8(a) is a curve of the relationship between the rotation steps of the peristaltic pump and the water depth; FIG. 8(b) is a fitted curve for water depths of 6-18 meters;

fig. 9 is an experimental graph of the lowest detection concentration of the monitor provided by the embodiment of the invention.

In the figure: 1. sealing the cabin; 2. an upper support plate; 201. a spectrometer; 202. a laser; 203. a Raman front light path; 204. an air pressure balancing bottle; 205. a cuvette fixing frame; 3. a plastic disc; 4. a rear end cap; 5. a lower support plate; 501. a DC-DC power supply; 502. a main controller of the single chip microcomputer; 503. a waste liquid storage bin; 504. a throttle valve; 505. a hard pipe straight joint; 506. a switching valve; 507. a peristaltic pump; 508. a gold sol storage bin; 509. an electromagnetic valve; 510. an external thread straight joint; 511. a stepper motor driver; 512. a serial server; 6. a filter; 7. a watertight electrical joint; 8. a front end cover; 801. an internally threaded watertight electrical interface; 802. an internally threaded filter interface; 9. a flow cuvette.

Detailed Description

In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. This invention may, however, be embodied in many different forms than those specifically described herein, and it will be apparent to those skilled in the art that many more modifications are possible without departing from the spirit and scope of the invention.

In order to solve the problem that the existing detection method cannot monitor the polycyclic aromatic hydrocarbon pollutants in the seawater in situ, automatically and quickly, the invention aims to provide an instrument for monitoring the polycyclic aromatic hydrocarbon pollutants in situ in the underwater, which has the advantages of low detection limit, good stability, high automation degree, convenience in operation, simple structure, easiness in disassembly and assembly, attractive appearance and the like.

In the description of the present invention, the terms "mounted", "connected" and "assembled" when appearing herein are to be understood broadly, and may be, for example, mechanical or electrical connections, without explicit limitation; either directly or through an intermediary. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art according to specific circumstances.

The common components such as "O-ring", "teflon tube", "optical fiber", "elastic bag", "U-shaped ferrule", "bolt", "electrical circuit", etc. mentioned in the embodiments of the present invention are not shown in the drawings because their features do not affect the detailed description of the embodiments of the present invention, and those skilled in the art can understand the role of the above components in the present invention according to the detailed description of the embodiments.

In order to realize in-situ monitoring of polycyclic aromatic hydrocarbon pollutants in seawater by utilizing a surface enhanced Raman scattering technology and adopting a gold sol enhanced substrate, the invention specifically provides a monitoring method of a polycyclic aromatic hydrocarbon ocean in-situ monitor, which comprises the following steps: in-situ seawater accurate sampling and quantitative adsorption enhancement of an enhanced substrate and a seawater sample are carried out by utilizing a multi-channel and automatic sampling and mixing mechanism, so that polycyclic aromatic hydrocarbon in the seawater sample generates a surface enhanced Raman scattering effect; and carrying out in-situ monitoring on the pollution of the marine polycyclic aromatic hydrocarbon by using a sampling and mixing mechanism, a spectrum detection mechanism and a hardware control module.

The technical solution of the present invention will be further described with reference to the illustrative examples.

As shown in fig. 1, the polycyclic aromatic hydrocarbon ocean in-situ monitor provided by the invention comprises:

the sealed cabin 1, the rear end cover 4 and the front end cover 8 form a sealed shell of the invention.

The filter 6 and the watertight electric connector 7 are installed on the front end cover 8 through threads, and the installation positions are determined according to the layout in the sealed cabin 1; an upper supporting plate 2 and a lower supporting plate 5 are arranged in the sealed cabin 1 and are fixed with a front end cover 8 and a plastic disc 3 through bolts to form an integrated structure.

As shown in fig. 2, for the spectrum detection mechanism, a spectrometer 201, a laser 202, and a raman front optical path 203 are fixed on the upper support plate 2 by bolts, a suitable distance is left between the spectrometer 201, the laser 202, and the raman front optical path 203 for optical fiber connection, the spectrometer 201 is connected with a collection sub optical path of the raman front optical path 203 by an optical fiber, and the laser 202 is connected with an excitation sub optical path of the raman front optical path 203 by an optical fiber; the cuvette fixing frame 205 is fixed on the upper support plate 2 in a way that the objective lens barrel of the Raman preposed optical path 203 is attached to the cuvette fixing frame 205, the flowing cuvette 9 can be vertically placed in the cuvette fixing frame 205 (as shown in figure 7), and the interface for connecting the flowing cuvette 9 with the peristaltic pump 507 is downward, so that a water sample can be conveniently pumped into the flowing cuvette 9 and waste liquid in the flowing cuvette 9 can be conveniently drained; the air pressure balance bottle 204 is fixed on one side of the cuvette fixing frame 205 through a U-shaped hoop, and an elastic bag arranged on the air pressure balance bottle 204 is connected with one interface of the flowing cuvette 9 through a Teflon tube. When the spectrum detection is needed, the sampling and mixing mechanism pumps and transports the water sample to be detected and the gold sol into the flowing cuvette 9, and then the spectrum detection mechanism works to excite and collect the surface enhanced Raman scattering optical signals of the water sample to be detected so as to form the surface enhanced Raman spectrum of the seawater sample.

As shown in fig. 3, for the sampling and mixing mechanism, the left and right sides of the electromagnetic valve 509 are respectively provided with the external thread through connector 510 and the throttle valve 504, and are connected through the stainless steel clamping sleeve, and the throttle valve 504 is used for adjusting the flow rate of the collected seawater; a hard pipe straight joint 505 is arranged on the other side of the throttle valve 504 and is used as an intermediate medium to connect the stainless steel capillary and the Teflon pipe; the switching valve 506 is fixed on the lower support plate 5 through a U-shaped hoop; the peristaltic pump 507 is fixed on the lower supporting plate 5 through bolts; a first channel of the switching valve 506 is connected with the hard tube straight joint 505 through a Teflon tube, a second channel is connected with the colloidal gold storage bin 508, a third channel is used for extracting air in the cabin, a channel No. 4 is connected with the waste liquid storage bin 503, and a common channel of the switching valve 506 is connected with a water inlet of a pump tube of the peristaltic pump 507; the water outlet of the pump pipe of the peristaltic pump 507 is connected with the lower end interface of the flow cuvette 9 through a Teflon pipe. When an environmental water sample needs to be collected and mixed with the gold sol reinforced substrate, the sampling and mixing mechanism quantitatively samples the seawater sample and the gold sol reinforced substrate and transports the seawater sample and the gold sol reinforced substrate to a flow cuvette 9 (shown in fig. 6) by opening a switch of an electromagnetic valve 509 and controlling the operation coordination of a switching valve 506 and a peristaltic pump 507, and finally closes the electromagnetic valve 509. It is emphasized that the present invention adjusts the volume of the collected water sample by adjusting the number of rotation steps of the peristaltic pump 507.

As shown in fig. 4, for the hardware control module, the serial server 512, the mcu 502 and the DC-DC power supply 501 are all fixed to the lower support plate 5 by single-ended studs. The hardware control module, the watertight electrical connector 7 and the devices in the underwater monitoring cabin are connected by corresponding electrical lines.

The serial server 512 is used for communicating and converting an Ethernet of the overwater terminal and an RS232 device in a monitoring cabin, the single-chip microcomputer main controller 502 is used for collecting and uploading monitored temperature and humidity data in real time and controlling the opening and closing of the electromagnetic valve 509, the DC-DC power supply 501 performs voltage reduction output on the voltage transmitted by the overwater terminal to provide a power supply for the device in the cabin, and the stepping motor driver 511 is used for controlling the operation of a peristaltic pump.

As shown in fig. 5, two through holes are drilled on the front end cover 8, and threads are tapped into the through holes, wherein the internal thread watertight electrical interface 801 is an interface of the watertight electrical connector 7, and the internal thread filtering interface 802 is an interface of the filter 6 and the external thread through connector 510; the filter 6 is arranged on the outer side of the front end cover 8, the external thread straight-through joint 510 is arranged on the inner side of the front end cover 8, and an O-shaped ring is arranged at the mounting position for waterproof sealing.

The watertight electric joint 7 is used as a medium for communication with an upper computer and external power supply; the filter 6, the female filter port 802 and the male straight-through connector 510 form a channel for collecting an environmental water sample.

The invention also provides a monitoring method of the polycyclic aromatic hydrocarbon ocean in-situ monitor, which comprises the following steps:

the equipment is lowered to a designated depth underwater, when sampling is carried out, after the electromagnetic valve 509 is controlled to be opened through the single chip microcomputer main controller 502, the common channel is connected with the first channel through the switching valve 506, the peristaltic pump 507 rotates forwards for a certain number of steps, a certain volume of seawater samples are collected into the common channel, the common channel is connected with the third channel through the switching valve 506, the peristaltic pump 507 rotates forwards for a certain number of steps again, the seawater samples in the common channel are transported to the flow cuvette 9 through air in the underwater monitoring cabin, and finally the electromagnetic valve 509 is closed; when a seawater sample and a gold sol enhanced substrate are mixed, the switching valve 506 is controlled to connect the public channel with the second channel, the peristaltic pump 507 rotates forwards for a certain number of steps, a certain amount of the gold sol enhanced substrate is pumped into the public channel, the switching valve 506 enables the public channel to the third channel, the peristaltic pump 507 rotates forwards for a certain number of steps again, the gold sol enhanced substrate is transported into the flow cuvette 9 by using air in the underwater monitoring cabin to be mixed and adsorbed with the seawater sample, and then the surface enhanced Raman scattering effect is generated.

When the spectrum detection is carried out, the upper computer controls the laser 202 to emit laser with certain power, the laser is focused into the flowing cuvette 9 through the Raman preposed light path 203, the surface enhanced Raman scattering light signal of the seawater sample is excited, and then the spectrometer 201 is controlled to collect the surface enhanced Raman spectrum of the seawater sample and transmit the spectrum data to the upper computer.

After the spectrum detection work is finished, the mixed waste liquid in the flowing cuvette 9 is discharged so as to detect the seawater sample next time, the switching valve 506 is controlled to transfer the public channel to the No. 4 pipeline and the peristaltic pump 507 to rotate reversely for a certain number of steps, and the waste liquid is transported to the waste liquid storage bin 503 from the flowing cuvette 9. After primary spectrum detection, the flow cuvette 9 needs to be cleaned, the cleaning work is similar to the sampling and waste discharge work, the sampling and mixing mechanism is controlled to transport the seawater of the next station to be detected to the flow cuvette 9 to complete cleaning, and finally the cleaning waste liquid is transported to the waste liquid storage bin 503.

After the detection work of the established underwater organic pollutants is finished, the underwater organic pollutants are salvaged to the shore, the surface of the underwater organic pollutants is cleaned and subjected to rust prevention treatment, the front end cover 8 is opened, the sealed cabin 1 is separated, the waste liquid storage bin 503 is taken out of the device, and the waste liquid is properly treated.

In a preferred embodiment of the present invention, in order to reduce the weight of the present invention, the capsule 1, the rear cover 4, the front cover 8, the upper support plate 2 and the lower support plate 5 are made of aluminum alloy, and at the same time, as many slots as possible are cut at the vacant positions of the upper support plate 2 and the lower support plate 5. In addition, the surface of the sealed cabin 1 is subjected to electroplating process treatment, so that the corrosion resistance of the sealed cabin 1 is improved.

In a preferred embodiment of the invention, the structure within the cabin is monitored underwater. The underwater monitoring cabin is not limited to a double-layer supporting plate structure, but can also be a single-layer supporting plate structure, but the double-layer supporting plate structure has the beneficial effects that the space in the cabin can be maximally utilized, and the volume of the underwater monitoring cabin is compressed.

In a preferred embodiment of the invention, the solenoid valve is replaced. The electric ball valve can be used for executing the opening and closing functions of the seawater sample pipeline, but the electric ball valve is slow in executing action, and the price of the ball valve with the small sampling drift diameter is higher.

In a preferred embodiment of the invention, the volume of the sample is controlled. The invention changes the sample injection volume by changing the rotation steps of the peristaltic pump 507, and can also control the sample injection volume by changing the rotation time of the peristaltic pump 507.

Secondly, the technical solution of the present invention is further described below with reference to the application examples.

The monitor provided by the invention can be used for detecting organic pollutants in the sea and can also be used in the fields of pollution monitoring of inland lakes and rivers and the like.

For ocean current fluctuation and underwater part stability, the sealed cabin 1 of the embodiment is designed to be cylindrical, and the whole body is made of aluminum alloy materials processed by cation electroplating to improve the corrosion resistance of the equipment. The outer diameter of the cabin body is 224mm, the length is 573mm, and the thickness is 10mm, so that the requirements of pressure resistance and sealing performance can be met.

The support plate material in the capsule 1 in this embodiment is aluminum alloy, and all the dimensions are 482 × 182 (mm). The short edge part of the plastic disc is bent upwards by a metal plate, and a through hole is reserved at the bent part, so that the plastic disc can be conveniently fixed on the end cover and the plastic disc. The design of bending downwards of its long limit portion part panel beating increases anti deformability. And finally, reserving a fixing screw hole and an elliptical wiring through hole of the device on the supporting plate through size calculation.

In the invention, the watertight network cable is connected with the monitoring cabin through the watertight electrical connector, so the internal thread through interface for installing the watertight electrical connector is processed on the front end cover. The interface positions are shown in fig. 5.

During underwater monitoring, a seawater sample is required to be collected, so that a seawater sampling channel in the cabin is required to be communicated with an extra-cabin seawater environment. This embodiment needs to reserve a through-hole of established size on the front end cover, and the internal thread is processed at the through-hole both ends, installs the filter (having external screw adapter) in the front end cover outside, adopts external screw thread rotary clamping sleeve to connect the sea water sampling passageway installation survey in the front end cover. According to this embodiment, a seawater sample may be passed from the filter through the end cap through-hole into the seawater sampling passage. The interface position is shown in fig. 5.

In the present invention, a 1.5mL sample of seawater is taken and mixed in a flow cuvette with 0.5mL of gold sol enhancing substrate (mixing parameters are laboratory empirical values). In this embodiment, the air compressor and the sealed water tank combination device are used to simulate water pressures at different depths of 0-20 m to obtain a relationship between the water depth and the number of steps of rotation of the peristaltic pump when quantitatively collecting 1.5mL seawater samples at different depths and a fitting curve, as shown in fig. 8 for the relationship between the number of steps of rotation of the peristaltic pump and the water depth when quantitatively collecting 1.5mL seawater samples. Wherein, FIG. 8(a) is a curve of the relationship between the rotation steps of the peristaltic pump and the water depth; FIG. 8(b) is a fitted curve for water depths of 6-18 m.

From FIG. 8(a), it can be seen that there is a good linear relationship between the number of steps of the peristaltic pump and the depth of the water when 1.5mL of seawater samples are taken at different depths (0-20 meters). Data from 6-18 m water depth was taken as the fitted curve, as shown in fig. 8(b), with the fitted equation of-28.59 x +1388.64 and a fitting coefficient of 0.9972. According to the results of the embodiment, if the monitoring cabin is 18m underwater, the seawater can be collected by calculating from the fitting equation, and the number of the rotation steps of the peristaltic pump is set to 874 steps, namely about 1.5mL of seawater sample can be collected. By utilizing a programming technology, a fitting equation is programmed into control software, and the related rotation steps of the peristaltic pump are set according to the depth of the monitoring cabin, so that the key technical problem of quantitatively collecting 1.5mL of seawater samples at different depths (0-20 meters) can be solved.

In the embodiment, the number of the rotation steps of the peristaltic pump for collecting 1.5mL of seawater sample into the public channel can be determined according to a fitting equation; the number of peristaltic pump rotation steps to pump 0.5mL of the gold sol-enhanced substrate into the common channel was 546 steps. The rotation steps of the peristaltic pump for transporting the seawater sample and the gold sol reinforced substrate into the flow cuvette can be determined according to the length of an actual flow channel pipeline. The rotation steps of the peristaltic pump for transporting the waste liquid in the flowing cuvette to the waste liquid storage bin can be determined according to the length of an actual flow path pipeline.

In this embodiment, the raman front end optical path includes two parts, namely an excitation sub optical path and a collection sub optical path. The excitation sub-optical path is built by a plano-convex lens, a beam expanding lens group, a band-pass filter, a high-reflection mirror and an object space converging lens, and is used for collimating, expanding and reflecting a laser beam emitted by a laser and finally focusing the laser to a flowing cuvette to excite Raman scattering light of a seawater sample. The collecting sub-optical path is built by a double-dichroic sheet and an image side convergent lens which are arranged at an angle of 45 degrees, and the collecting sub-optical path has the functions of filtering Raman scattering light which is excited and collected by the object side convergent lens, eliminating Rayleigh scattering light, guiding the Raman scattering light into an optical fiber and reaching the inside of the spectrometer through the optical fiber. The laser excitation wavelength selects 785nm infrared light to eliminate fluorescence interference caused by chlorophyll and other substances in seawater. The light path adopts cage structure to build, and its beneficial effect is: 1) the cage structure is relatively stable, and the field application is facilitated; 2) the bottom of the cage plate is provided with a reserved mounting threaded hole which can be directly mounted on the supporting plate through screws, thereby being beneficial to system integration; 3) the cage structure is compact, which is beneficial to reducing the volume of the invention.

In this embodiment, a fixing frame is designed and manufactured for fixing the flow cuvette, and 205 in fig. 2 is a front view of the fixing frame. The fixing frame is composed of two parts, one part is a fixing frame cover, and the other part is a fixing frame main body. Oval incisions are processed on the front surface and the rear surface of the fixing frame main body, so that the flowing cuvette is conveniently irradiated by laser. The through hole is reserved at the lower end of the fixing frame main body and is used for placing a lower end interface of the flowing cuvette. The extending part of the bottom end of the side surface of the fixing frame body is reserved with a mounting through hole. The fixing frame cover is provided with a through hole for placing an upper port of the flowing cuvette. After the mobile cuvette is placed into the fixing frame main body, the fixing frame main body and the fixing frame cover are locked by screws. The cuvette fixing frame needs to be closely arranged in front of the object space converging lens of the Raman scattering light path.

Thirdly, the positive effects of the present invention will be further described with reference to the relevant results of the examples.

Through laboratory tests, the sampling precision of the sampling and mixing mechanism of the invention reaches +/-10 mu L, the sampling relative error is less than 0.5 percent, and the requirements of surface enhanced Raman spectrum detection are met; the lowest detection concentration of the polycyclic aromatic hydrocarbon is as low as 2 multiplied by 10 ^- ⁹ The polycyclic aromatic hydrocarbon pollutant in seawater can be effectively monitored in mol/L (laboratory, simple substance); the maximum power is only 80W, and the method is green and environment-friendly; the method comprises the following specific steps:

1. sample introduction precision: the following test data is provided for the sampling and mixing mechanism sample introduction precision data of the present invention. Pure water is selected as a test sample for sample injection precision test, and the density of the pure water is 1g/cm ³ When the sample injection mass is 1.0g by using an electronic balance (absolute accuracy: one ten thousandth gram), the sample injection volume is considered to be 1.0 mL. And controlling a sampling and mixing mechanism to continuously sample 1.0mL of water sample for 3 times, then powering off and restarting, and repeating the test process for 10 times. The test data are shown in table 1. According to the test data, the maximum sample injection error of the mechanism does not exceed +/-0.010 ml, so the sample injection precision is +/-10 mu L. The absolute value of the relative error of the sample injection average value is less than 0.5 percent, which indicates that the system has higher precision. The maximum standard deviation is 0.0062, the average standard deviation is 0.004396, and the repeatability and the stability are better.

TABLE 1 sample introduction accuracy test data

2. Minimum detection concentration: in order to obtain the lowest detection concentration of the present invention, the monitor was operated in the laboratory for a concentration of 1X 10 ^-9 mol/L、2×10 ^-9 mol/L and 5X 10 ^-9 And detecting by using a pyrene solution probe (common PAHs) at mol/L.

The experimental steps are as follows: 1) starting the monitor, preheating and initializing; 2) injecting a 1.5mL pyrene solution probe and a 0.5mL gold sol enhanced substrate into a flowing cuvette by using a sampling and mixing mechanism and mixing; 3) setting the integration time of a spectrometer to be 10s, setting the laser power to be 100mW, controlling a spectrum detection mechanism to repeat surface enhanced Raman spectrum detection for 5 times on a pyrene solution probe, and averaging to obtain stable and reliable spectrum data; 4) and discharging the mixed waste liquid in the flowing cuvette and cleaning the mixed waste liquid. And repeating the experimental steps for 3 times to obtain the surface enhanced Raman spectrum data of the pyrene sample with all concentrations. The experimental results of the monitor for the lowest detected concentration are shown in fig. 9.

As shown in FIG. 9, the pyrene sample was located at 588cm ^-1 Typical Raman feature peaks at Raman shifts are exemplified and compared to the enhanced base line for analysis as follows: when the concentration of the probe in the pyrene solution is 1X 10 ^-9 mol/L, wherein Raman characteristic peaks of pyrene samples do not exist; when the concentration of the probe in the pyrene solution is 2X 10 ^-9 mol/L, wherein the Raman characteristic peak of the pyrene sample exists at the position; when the concentration of the probe in the pyrene solution is 5X 10 ^-9 mol/L, where the Raman characteristic peak of the pyrene sample is also present. Therefore, the lowest detection concentration of the monitor can be obtained to be 2 multiplied by 10 ^-9 mol/L, excellent detection performance, and provides important practical support for realizing in-situ monitoring of PAHs pollutants in the ocean.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention, and the scope of the present invention is not limited thereto, and any modification, equivalent replacement, and improvement made by those skilled in the art within the technical scope of the present invention disclosed herein, within the spirit and principle of the present invention, should be covered within the scope of the present invention.

Claims

1. The utility model provides a polycyclic aromatic hydrocarbon ocean in situ monitor which characterized in that, polycyclic aromatic hydrocarbon ocean in situ monitor includes: the underwater monitoring cabin mixes the collected seawater sample and the gold sol enhanced substrate in the flowing cuvette (9), converges laser into the flowing cuvette (9), and simultaneously excites a surface enhanced Raman scattering optical signal of the seawater sample; collecting the surface enhanced Raman spectrum of the seawater sample, and transmitting the surface enhanced Raman spectrum data to the overwater terminal; the overwater terminal obtains pollution data of the polycyclic aromatic hydrocarbon in the seawater by identifying the Raman characteristic peak of the polycyclic aromatic hydrocarbon in the surface enhanced Raman spectrum of the seawater sample.

2. The polycyclic aromatic hydrocarbon ocean in situ monitor according to claim 1, wherein the aquatic terminal is positioned on a deck, and comprises an upper computer and a direct current power supply; the overwater terminal supplies power to the underwater monitoring cabin through a watertight network cable in a direct current mode and adopts Ethernet communication; a spectrum detection mechanism, a sampling and mixing mechanism and a hardware control module are integrated in the underwater monitoring cabin;

the upper computer sends a corresponding control command to the underwater monitoring cabin through a software interface, and recovers the state and the spectrum data quantity;

the spectrum detection mechanism consists of a spectrometer (201), a laser (202) and a Raman preposed light path (203) and is used for exciting and collecting the surface enhanced Raman spectrum of the seawater sample;

the sampling and mixing mechanism consists of a switching valve (506), a peristaltic pump (507), an enhanced substrate storage bin (508), an electromagnetic valve (509), an external thread through joint (510), a filter (6), a waste liquid storage bin (503), a throttle valve (504), an air pressure balance bottle (204) and a flow cuvette (9), and is used for quantitatively collecting a seawater sample, mixing the seawater sample and a gold sol enhanced substrate, cleaning a pipeline, discharging and storing mixed waste liquid;

the hardware control module consists of a stepping motor driver (511), a serial server (512), a DC-DC power supply (501), a singlechip main controller (502) and a watertight electric joint (7); the device is used for receiving an instruction of the water terminal to control each device to work and transmitting monitored temperature and humidity data to the water terminal in real time;

the serial server (512) is used for converting the communication between the overwater terminal and the devices RS232 in the monitoring cabin through the Ethernet, the single-chip microcomputer main controller (502) is used for collecting and uploading temperature and humidity monitoring data in real time and controlling the opening and closing of the electromagnetic valve (509), the DC-DC power supply (501) performs voltage reduction processing on the electric power transmitted by the overwater terminal so as to meet the power supply requirements of the devices in the cabin, and the stepping motor driver (511) is used for controlling the operation of the peristaltic pump (507).

3. The polycyclic aromatic hydrocarbon ocean in situ monitor according to claim 2 wherein the spectrometer (201) is used for converting surface enhanced Raman scattering optical signals of a seawater sample into electrical signals;

the laser is used for emitting laser beams with 785nm wavelength;

the Raman front light path (203) is used for expanding, collimating and filtering the laser beam emitted by the laser, focusing the laser beam into the flowing cuvette (9), exciting a surface enhanced Raman scattering light signal of the seawater sample, collecting the surface enhanced Raman scattering light signal of the seawater sample, filtering the surface enhanced Raman scattering light signal, and guiding the surface enhanced Raman scattering light signal into the spectrometer (201);

the peristaltic pump (507) is used for providing power for transporting fluid, and the sample injection volume of the reagent is controlled by controlling the rotation steps of the peristaltic pump (507);

the switching valve (506) is provided with a common channel and six sub-channels, a lower end interface of the flow cuvette (9) is connected with the common channel of the switching valve (506), the seawater sampling channel, the in-cabin air channel, the gold sol enhanced substrate channel and the waste discharge channel are respectively connected with the sub-channels of the switching valve (506), and different reagents are transported into the flow cuvette (9) and discharged from waste liquid of the flow cuvette (9) by switching the connection of the common channel and the sub-channels;

the electromagnetic valve (509) is used for opening or closing the seawater sampling channel, and the singlechip main controller (502) is used for carrying out power-on control so as to control the opening and closing of the channel inside and outside the cabin;

the throttle valve (504) is used for adjusting the flow during seawater sampling so as to ensure that the seawater flow velocity in the cabin is uniform;

the air pressure balance bottle (204) is internally provided with an elastic bag which is connected with the upper end port of the flow cuvette (9) through a hose; when the reagent enters the cuvette (9), the air in the cuvette is discharged into the air pressure balance bottle (204); when the waste liquid is discharged, the air in the air pressure balance bottle (204) returns to the cuvette;

the filter (6) is arranged on the outer side of a front end cover (8) of the underwater monitoring cabin and is used for filtering silt and suspended matters in a seawater sample;

the external thread straight-through joint (510) is used for connecting the seawater sampling channel to the inner side of a front end cover (8) of the underwater monitoring cabin, and a seawater sample firstly passes through the filter (6) and then enters the seawater sampling channel through a channel reserved in the front end cover;

the serial server (512) is used for converting the Ethernet communication of the overwater terminal into RS232 serial communication, so that all serial devices are interconnected, and a communication line of the overwater terminal upper computer and the serial devices in the cabin is established;

the stepping motor driver (511) is used for driving a stepping motor in the peristaltic pump (507) to rotate by a corresponding stepping angle according to a set direction; the DC-DC power supply (501) is used for supplying direct current with different voltages of 24V/12V/5V to electrical appliances;

the watertight electrical connector (7) is used for providing an interface for a watertight network cable to access the underwater monitoring cabin.

4. The polycyclic aromatic hydrocarbon ocean in situ monitor according to claim 3, wherein the spectrometer (201) is coupled with a collector sub-optical path of the Raman front-end optical path (203) through an optical fiber, and the laser (202) is coupled with an exciter sub-optical path of the Raman front-end optical path (203) through an optical fiber;

the spectrometer (201), the laser (202) and the Raman preposed light path (203) are placed in a delta shape, the Raman preposed light path (203) is arranged in front, and the spectrometer (201) and the laser (202) are arranged behind and fixed on an upper supporting plate (2) in the sealed cabin (1) through bolts;

the communication and power supply circuit of the spectrometer (201) and the laser (202) are connected with the equipment hardware control module through a wire passing hole reserved in the upper support plate (2);

the filter (6) adopts a stainless steel filter screen and is used for filtering silt and suspended particles in the water sample; the filter (6) is fixed on the outer side of the front end cover (8) through threads;

the external thread straight-through joint (510) is arranged on the inner side of the front end cover (8) through threads and an O-shaped ring and is used for connecting the stainless steel clamping sleeve to the front end cover (8) so as to form a pipeline for a water sample to enter the sealed cabin (1);

the electromagnetic valve (509) is mounted on the lower layer supporting plate (5) through a bolt and is connected with one side of a ferrule interface of the external thread through connector (510) through a stainless steel ferrule; the throttle valve (504) is arranged on the other side of the electromagnetic valve (509) and is connected with the electromagnetic valve (509) through a stainless steel clamping sleeve;

the gold sol storage bin (508) is arranged on the lower layer supporting plate (5) through a U-shaped hoop and is used for storing an elastic bag filled with gold sol;

the waste liquid storage bin (503) is arranged on the lower layer supporting plate (5) through a U-shaped hoop and is used for storing an elastic bag filled with waste liquid.

5. The polycyclic aromatic hydrocarbon ocean in situ monitor according to claim 3, wherein the air pressure balance bottle (204) is mounted on the upper layer supporting plate (2) through a U-shaped hoop and used for fixing the air pressure balance elastic bag, and the air pressure balance elastic bag is connected with one interface of the flow cuvette (9) through a Teflon tube;

the switching valve (506) is a multi-channel switching valve, and each channel of the switching valve (506) is sequentially connected with a throttle valve (504), a colloidal gold storage bin (508), a waste liquid storage bin (503) and an elastic bag in an air pressure balance bottle (204) by adopting a Teflon pipe and an inverted cone connector;

the switching valve (506) is arranged on the lower layer support plate (5) in parallel and is fixed through a U-shaped hoop; the water inlet of the peristaltic pump (507) is connected with the common channel of the switching valve (506) through an inverted cone connector, and the water outlet of the pump pipe is connected with the lower end interface of the flow cuvette (9); the peristaltic pump (507) is installed on the lower layer supporting plate (5) in a penetrating mode and fixed through bolts.

6. The polycyclic aromatic hydrocarbon ocean in-situ monitor according to claim 2, wherein when the sampling and mixing mechanism receives a sampling and mixing command sent by the upper computer, the following steps are automatically executed: the electromagnetic valve (509) is opened, the switching valve (506) connects the public channel with the seawater sampling channel, the peristaltic pump (507) rotates forward for a certain number of steps, a certain amount of seawater sample is sucked into the public channel, the electromagnetic valve (509) is closed, the switching valve (506) connects the public channel with the air channel in the cabin, the peristaltic pump (507) rotates forward for a certain number of steps again, the air in the cabin is utilized to transport the certain amount of seawater sample in the public channel into the flow cuvette (9), the switching valve (506) connects the public channel with the gold sol reinforced substrate channel, the peristaltic pump (507) rotates forward for a certain number of steps, the certain amount of gold sol reinforced substrate is sucked into the public channel, the switching valve (506) connects the public channel with the air channel in the cabin, the peristaltic pump (507) rotates forward for a certain number of steps again, the gold sol enhanced substrate in the public pipeline is transported to a flowing cuvette (9) by utilizing the air in the cabin, and is mixed and adsorbed with the seawater sample, so that the surface enhanced Raman scattering effect is generated.

7. The polycyclic aromatic hydrocarbon ocean in-situ monitor according to claim 1, wherein the underwater monitoring chamber is internally provided with an upper and lower double-layer supporting plate integrated structure, and the spectrum detection mechanism, the sampling and mixing mechanism and the hardware control module are integrated into the underwater monitoring chamber.

8. A monitoring method for realizing the polycyclic aromatic hydrocarbon ocean in-situ monitor as claimed in any one of the claims 1 to 7, wherein the monitoring method for the polycyclic aromatic hydrocarbon ocean in-situ monitor comprises the following steps: in-situ seawater accurate sampling and quantitative mixed adsorption of an enhanced substrate and a seawater sample are carried out by utilizing a multi-channel and automatic sampling and mixing mechanism, so that polycyclic aromatic hydrocarbon in the seawater sample generates a surface enhanced Raman scattering effect;

9. The method for monitoring the polycyclic aromatic hydrocarbon ocean in-situ monitor according to claim 8, wherein the method for monitoring the polycyclic aromatic hydrocarbon ocean in-situ monitor specifically comprises the following steps:

when sampling is carried out, after the electromagnetic valve (509) is controlled to be opened through the singlechip main controller (502), the public channel is connected with the first channel through the switching valve (506), the peristaltic pump (507) rotates forwards for a certain number of steps, a certain volume of seawater sample is collected into the public channel, the public channel is connected with the third channel through the switching valve (506), the peristaltic pump (507) rotates forwards for a certain number of steps again, the seawater sample in the public channel is transported to the flow cuvette (9) through air in the underwater monitoring cabin, and finally the electromagnetic valve (509) is closed;

when a seawater sample and the gold sol reinforced substrate are mixed, the switching valve (506) is controlled to connect the public channel with the second channel, the peristaltic pump (507) rotates forwards for a certain number of steps, a certain amount of the gold sol reinforced substrate is extracted into the public channel, the switching valve (506) connects the public channel with the third channel, the peristaltic pump (507) rotates forwards for a certain number of steps again, and the gold sol reinforced substrate is transported into the flow cuvette (9) to be mixed with the seawater sample by utilizing air in the underwater monitoring cabin;

when spectrum detection is carried out, after the upper computer controls the laser to emit laser with certain power, the laser is converged into the flowing cuvette (9) through the Raman preposed optical path (203) to excite the surface enhanced Raman scattering optical signal of the seawater sample, and then the spectrometer (201) is controlled to collect the surface enhanced Raman spectrum of the seawater sample and transmit the spectrum data to the upper computer;

after the spectrum detection is finished, discharging the mixed waste liquid in the flowing cuvette (9); controlling a switching valve (506) to transfer the public channel to a No. 4 pipeline, reversely rotating a peristaltic pump (507) for a certain number of steps, and transporting the waste liquid from the flowing cuvette (9) to a waste liquid storage bin (503);

after the spectrum detection, the flowing cuvette (9) is cleaned, the sampling and mixing mechanism is controlled to transport the seawater of the next station to be detected to the flowing cuvette (9) to complete cleaning, and finally the cleaning waste liquid is transported to the waste liquid storage bin (503).

10. A monitoring device for monitoring pollution of organic pollutants, pesticides and antibiotics in a water body, which is characterized in that the monitoring device is provided with the polycyclic aromatic hydrocarbon ocean in-situ monitor as claimed in any one of claims 1 to 7.