RU177930U1 - AUTONOMOUS FLUORIMETRIC COMPLEX FOR DETERMINING THE CONTENT OF PHYTOPLANKTON CHLOROPHYLL AND GENERAL WEIGHTED SUBSTANCE IN AQUEOUS ENVIRONMENT - Google Patents

Abstract

The utility model relates to the field of optical studies of water masses of freshwater and marine bodies of water, including those with a significant concentration of total suspended matter. The fluorimetric complex contains one or several pulsed or continuous optical sources of excitation of intravital fluorescence of phytoplankton, a fluorescence signal photodetector, an excitation signal intensity registration photodetector, allowing to take into account the instability of the exciting light and correct the measurement results, one additional light receiver in the excitation band that detects the scattered water due to which simultaneously with the content of phytoplankton It is Busy content of total suspended solids. The technical result consists in expanding the set of parameters measured by one device and, accordingly, the completeness of the collection of contact data on the state of the aquatic environment. 4 s.p. f-ly; 1il.

Description

The utility model relates to the field of optical studies of water masses of freshwater and marine bodies of water, including those with a significant concentration of total suspended matter. The content of phytoplankton in natural water and the dynamics of its change testify not only to the state of the feed base, which is primary for all aquatic inhabitants, but also to the level of pollution of water bodies, water saturation with oxygen, direction and speed of movement of water masses. Currently widely used for monitoring the concentration of microalgae in the marine environment are satellite remote sensing systems, which make it possible to record the spectra of radiation rising from the water surface caused by exposure to sunlight. With all the advantages of satellite monitoring, such as wide coverage of water bodies regardless of borders, quick access to results, this method also has disadvantages. These include insufficient spatial resolution, irregularity in obtaining information in a specific area of the water surface, analysis of mainly surface layers, and a strong dependence of the results on cloud cover.

Contact monitoring does not exclude, but supplements satellite sounding, its capabilities are constantly expanding thanks to the use of automated equipment, and data availability is improved through the use of modern communications. Sensors installed at points of contact with a controlled environment can measure many quantitative and qualitative parameters and processes associated with water with high accuracy and sufficient frequency. In another embodiment of the use of contact data acquisition systems, flowing or towed devices are moved by the vessel, as a result, information is collected on the parameters of the aquatic environment over a large area at a known time.

At the same time, it is not enough to study the spectral characteristics to build a complex picture of the processes occurring in the aquatic environment. It is important to take into account temperature, salinity, concentration of total suspended and dissolved organic matter, flow rate and other characteristics, as well as their distribution in the water column and the change in time, including time of day. A comprehensive study of the aquatic environment is carried out by combining various contact sensors at coastal posts or a moving vessel. A wide range of contact data allows us to quickly draw conclusions not only about the concentration of phytoplankton, but also about such an important characteristic of its state as photosynthetic activity of cells. When studying the water masses of the shelf zones of the seas, especially near the mouths of the rivers, as well as the rivers themselves, the concentration of total suspended matter in water should also be controlled.

To ensure efficient collection of contact data on the state of the aquatic environment, easily integrable devices combining compactness, energy efficiency, the possibility of autonomous operation and remote data transmission are required. Of great importance is the ability to measure with a single device a wide range of parameters characterizing both water and the state of the photosynthetic apparatus of the microalgae contained in it. The most modern methods for studying the properties of sea and river water are optical, based on the phenomena of absorption, scattering, and fluorescence. This is due to the relative transparency of water, the ability to provide selectivity by varying the set of spectral-temporal characteristics of the test radiation, and significant progress in the elemental base.

BACKGROUND

Various systems are known for performing fluorimetric measurements in an aqueous medium.

US Pat. No. 4,293,225 describes an immersion fluorometer having a source of transmitting light pulses into a liquid into which a fluorimeter is immersed to cause fluorescence of a material in the form of a suspension, and a fluorescence detector, wherein a second detector is used to measure the light flux intensity of the source during each pulse light, the outputs of the fluorescence detector and the second detector are measured at each pulse of light, and their ratio is used to determine the intensity of fluorescence is relatively intense awn of light causing fluorescence. This mechanism compensates for the effects of both short-term and long-term drift, especially in the light source. The disadvantage of this device is the inability to simultaneously measure the total suspended matter in the aquatic environment. Also, the device does not allow separate recording of chlorophyll fluorescence in the far red and near infrared regions to determine the state of the photosynthetic apparatus of the chlorophyll phytoplankton.

In US Pat. No. 5,350,922, an underwater sensor is intended to detect or measure the concentration of suspended particles in water. The sensor is designed to measure light scattered at almost all angles, including forward scattering, backscattering and multiple scattering from particles suspended in water, using a very short light path. The light scattering sensor includes a light source, a photodetector and a light screen, eliminating direct radiation from the source to the receiver. The concentration of suspended particles in natural waters is broadly proportional to the measured intensity of the scattered light. The small and simple design of the sensor allows you to use it as a consumable item, and for long-term use. The disadvantage of the sensor is that when it is used, only the concentration of suspended particles in natural waters is measured, but the fluorescence of chlorophyll is not measured.

The invention patent No. 2354958 describes a method for fluorimetric determination of photosynthesis parameters of photoautotrophic organisms, including phytoplankton, and a device for its implementation. To determine the state of photosynthetic organisms, pulses of exciting light lasting 1-5 μs with an interval between pulses of 50-100 ms cause chlorophyll fluorescence. Based on the totality of the measured values of the fluorescence intensity, the fluorescence parameters are determined, which are used to judge the state of the photosynthetic apparatus, and the photosynthesis parameters of the studied object are determined, while the characteristics of chlorophyll fluorescence are measured with constant background illumination. The state of the photosynthetic apparatus, including photosystem I and photosystem II, is determined by the amplitude-time dependences of chlorophyll fluorescence in a band with a wavelength of 680 nm or more, which is ensured by the use of a boundary filter KS 18. The disadvantage of this device is the inability to separately record the fluorescence of chlorophyll in the far red and near infrared regions corresponding to the response of photosystem I and the response of photosystem II, as well as the inability to measure the total suspended matter in ne environment.

The closest analogue to a utility model that can be considered a prototype is described in US Pat. No. 6,020,587 A. A meter of chlorophyll content in plants that collects light reflected from a plant and separates it in two different wavelength ranges. These wavelength ranges, or channels, have central wavelengths of 700 nm and 840 nm. The light collected in these two channels is recorded using photodetectors and amplifiers, and then digitized. The light level from the light source is also recorded. The ratio of the intensities of reflected light in two separate wavelength ranges indicates the relative level of physiological stress in plants. The disadvantage of this device is the inability to simultaneously measure the content of chlorophyll in plants to measure the total suspended matter in the aquatic environment.

Thus, well-known examples of devices do not allow measuring the concentration of phytoplankton chlorophyll in an aqueous medium with an assessment of the state of the phytoplankton photosynthetic apparatus and the level of physiological stress in aquatic plants due to the separate recording of intravital fluorescence of chlorophyll in the far red and near infrared spectral regions corresponding to the response of photosystem I and response of photosystem II, with simultaneous measurement of the total suspended matter in the aquatic environment, which is especially important but in waters with increased turbidity, characteristic of rivers and seas near river estuaries. In addition, the described devices do not contain information about using them as autonomous measuring systems with remote transmission of the results.

Utility Model Disclosure

The technical result achieved from the implementation of the described utility model consists in expanding the set of measured parameters and, accordingly, completeness of the collection of contact data on the state of the aquatic environment.

The essence of the utility model is that the fluorimetric complex contains:

1) one or more pulsed optical sources directed into the aquatic environment to excite the intravital fluorescence of phytoplankton;

2) a photodetector that receives optical radiation from the phytoplankton chlorophyll fluorescence from an aqueous medium, equipped with an optical filter that suppresses radiation in the spectral band of optical sources and an optical screen that excludes direct and specular radiation from optical sources;

3) a photodetector, which receives mainly radiation from an exciting optical source, which allows one to take into account the instability of the exciting light and correct the measurement results;

4) a photodetector that receives the radiation of optical sources scattered by the aqueous medium, equipped with an optical filter that suppresses radiation in the band of the fluorescence spectrum of the chlorophyll of phytoplankton and transmits radiation in the spectrum of the spectrum of optical sources, and an optical screen that excludes direct and specular radiation from optical sources;

5) a signal control and processing device that synchronizes the operation of the fluorometric complex, amplifies, filters, and digitizes the received optical signals, calculates the results of measuring the phytoplankton chlorophyll fluorescence intensity and the radiation intensity scattered in the aqueous medium, taking into account the instability of the intensity amplitude of the optical source;

6) autonomous or (and) network power supply, stabilizers and other power devices, power circuits;

7) a device for transmitting results, including wireless, and (or) a device for indicating results;

8) a device that ensures the passage of radiation from optical sources into the aquatic environment and the passage of radiation from the aqueous medium to photodetectors while protecting the electronic circuits from physical contact with water, which can be implemented in the form of an optically transparent tube, an optically transparent plate, an optically transparent cell, optical fibers;

9) may additionally contain not one, but two photodetectors that receive optical radiation from the phytoplankton chlorophyll fluorescence separately from the aqueous medium separately in the far red and near infrared ranges of the spectrum, equipped with appropriate optical filters that suppress radiation in the spectrum band of optical sources and transmit radiation of fluorescence in the required band spectrum;

10) may additionally contain a device for calculating the concentration of chlorophyll of phytoplankton and the concentration of total suspended matter contained in the aqueous medium, taking into account calibration factors;

11) may further comprise a temperature sensor for simultaneously measuring the temperature of the aqueous medium;

12) may additionally contain a photodetector for recording the background illumination of the aquatic environment, allowing to take into account the influence of natural or artificial light on the state of the photosynthetic apparatus of the chlorophyll phytoplankton;

13) the above devices can be placed in one or more cases connected by communication lines.

The essence of the utility model is illustrated by a functional diagram (Fig. 1).

In FIG. 1 shows a functional diagram of an autonomous fluorimetric complex for determining the chlorophyll content of phytoplankton and total suspended matter in an aqueous medium, the numbers denote:

1 - aquatic environment;

2 - photodetectors of fluorescence radiation;

3 - pulsed optical source;

4 - photodetector radiation of an optical source;

5 - photodetector of radiation scattered by the aqueous medium;

6 - control device and signal processing;

7 - temperature sensor;

8 - optically transparent window;

9 - power supply;

10 - device for transmitting measurement results;

11 - an additional photodetector of fluorescence radiation, characterized by a range of spectrum.

Utility Model Implementation

The described utility model of an autonomous fluorimetric complex is implemented in the form of two blocks: a submersible block in contact with the aquatic environment (1) and a power and control unit located above the surface of the water.

The sealed housing of the submersible block consists of a cylindrical base, an upper flange, a cable pipe, a lower flange, a removable module made of 12X18H10T stainless steel, as well as an o-ring and screw ties. The cylindrical base 160 mm high is made of a seamless pipe with an external diameter of 89 mm and a wall thickness of 5 mm. The upper flange is made of sheet steel 5 mm thick and is attached by argon welding to a cylindrical base. A cable pipe with a diameter of 20 mm and a thickness of 4 mm is inserted into the center of the upper flange, and the pipe is also attached by welding. In the operating position of the immersion unit, the cable pipe protrudes from the water and ends with an adapter on a flexible hose attached with a thread.

The lower flange made of sheet steel, attached by welding to the base, contains 6 holes for screw ties and a groove for the o-ring. An optical module is pressed against the bottom flange using screws, nuts and washers made of stainless steel, the lower part of which is made in the form of a 5 mm thick stainless steel disk. The disk contains 6 holes for screw ties and a groove for the o-ring. A silicone ring with an outer diameter of 98 mm and a thickness of 6 mm ensures the tightness of the immersion unit.

In the center of the disk of the optical module there is an opening into which a window (8), transparent in the visible and near infrared, is glued. As a window, a flat-convex lens with a diameter of 58 mm is used, which due to focusing properties allows to increase sensitivity. For gluing the lens, a waterproof TK 400 two-component adhesive is used, the flat side of the lens facing out.

On the inside, a support ring made of aluminum alloy d16-T 8 mm thick is attached to the disk of the optical module with screws. On this ring, all other devices of the immersion unit are installed, including two light sources, two fluorescence photodetectors, a source radiation control photodetector, scattered radiation photodetector, thermal sensor, control device, screens and light filters. The electronic parts of all of the above devices of the submersible block are made in the form of specially designed double-sided printed circuit boards with surface mounting, active and passive elements in small-sized cases are used.

Photodetectors (2) are installed in the center of the optical module design on special racks at some distance from the window (lens) to provide the angle of incidence required for the interference filter. A silicon photocell VBPW34S with a sensing element area of 7.5 mm ² is located on one side of the PCB of the photodetector, and on the other, the remaining elements, including a four-stage amplifier, a reference voltage source, a photodiode bias voltage stabilizer, and a power circuit. Used chips ADA4841-1YRZ, AD8605ARTZ and ADR421BRZ. The receivers are mounted at a small angle to the axis of the optical module to ensure maximum fluorescence emission, the angle was selected empirically.

A custom-made interference filter is pressed to the board from the side of the photodiode through a silicone seal. Three sets of filters were made to isolate fluorescence radiation in the red, infrared and both bands, the filter transmission range was 680-700, 710-770 and 650-790 nm, respectively. Filter sizes - 16 × 12 mm, thickness - 5 mm. On the other hand, the filters facing the aquatic environment, to the device limiting the solid angle of the rays incident on the photodiode, an additional optical filter is glued with silicone sealant. The filter is 16x20 mm in size, cut with a water-cooled diamond saw from a standard KS-11 glass filter.

Two LED pulsed optical sources are installed on both sides of the photodetectors (3). Sources are made on printed circuit boards, LEDs LXML-PR02-A900 are used, emitting a wavelength of 447.5 nm with a half width of 20 nm. The photodiode current stabilizer is made according to the classical scheme using an IRF7401 field effect transistor and an AD8605ARTZ operational amplifier. Voltage is supplied to the inverting input of the amplifier from the source of the two chip resistors with a nominal value of 0.22 Ohms in the frame size 1206, and to the non-inverting voltage pulse generated by the IRLML6302TR transistor. The trigger pulse and the reference voltage are supplied from the control device. The pulse current of the LED was about 20 A, and the pulse duration was 5 μs.

Since it was experimentally established that the emission spectrum of LEDs contains a substantial component in the chlorophyll fluorescence band, optical filters 10 × 10 mm in size cut from a standard SZS-20 glass filter are installed on the light source boards. The angle of inclination of the radiation sources is selected so that their axes intersect at a distance of about 50 mm from the outer surface used as the lens window. The most practical is the fastening of the sources to the support ring using silicone sealant after fixing in the desired position using auxiliary means from the wire.

A control photodetector (4) is installed near the window, facing the radiation sources by the photodiode and located in the middle between them so that radiation from both sources gets on it. Despite the good stabilization of the pulsed current through the LEDs, the optical signal power is unstable, primarily due to changes in the ambient temperature. The control photodetector is designed to measure the actual intensity of the emitted optical light and then adjust the measured fluorescence intensity, which within tens of percent can be considered proportional to the intensity of the exciting signal. The control photodetector is made in the form of a printed circuit board, it uses a TEMD7000X01 photodiode and a single-stage amplifier on the AD8605ARTZ chip. No filters were used, since the intensity of the emitted light is several orders of magnitude higher than the intensity of the scattered light and the intensity of fluorescence.

Between the photodetectors, so as not to overlap the path of the fluorescence radiation rays from the aqueous medium, a photodetector for recording the intensity of the radiation scattered by the aqueous medium is installed (6). It uses the same photodiode as in the reference photodetector, but the amplifier is three-stage. The radiation scattered by an aqueous medium containing a suspension enters the photo diode through a window through a filter similar to that used in the sources. The relative position of the light sources and the scattered radiation receiver is selected so that the radiation of the sources reflected from both surfaces of the window does not reach the receiver. For additional suppression of radiation scattered not by the aqueous medium, but by internal structural elements, a ring glued to the receiver was used to narrow the solid angle of the incoming rays and blacken the structural elements and the casing inside the submersible block with black nitro paint.

Typically, suspension scattering measurements are made using red or infrared LEDs, since infrared light does not interfere with chlorophyll fluorescence measurements. But the mode of scattering of light at micrometer sizes of particles suspended in water is maintained in the entire visible range, so that the scattering intensity of the same blue radiation, which causes the fluorescence of chlorophyll, can be measured. A filter is used to eliminate interference from fluorescence radiation.

Since in the working state the housing of the submersible block is in thermal equilibrium with the aqueous medium, a thermal sensor (7) is installed inside the submersible block. It is fixed at a corner near the edge of the aluminum alloy ring; for better thermal contact, the KPT-8 heat-conducting paste was used. The sensor is made in the form of a narrow double-sided printed circuit board, on one side of which a metallized area is made in the lower layer, which is not covered with a protective mask. A temperature sensor of the DS18B20U type is located in the upper layer; to improve thermal contact with the metallized layer, vias and KPT-8 paste are used. The ATTINY2313A-MU microcontroller in a small-sized case, an ADM1485ARZ microcircuit to support the RS-485 interface and a 78L05 power regulator are also installed on the temperature sensor board.

The control device (6) is installed on special racks above the above nodes, since it does not require optical or thermal contact with the aqueous medium. The control device is made in the form of a printed circuit board and contains an ATMegal6A microcontroller, 4 ADCs, including 2 AD7686BRMZ microcircuits and AD7894ARZ-2 microcircuits, an ADR421BRZ voltage source, four amplifiers with zero offset, made on AD8605ARTZ operational amplifiers, and reference and input voltage buffers , an ADM1485ARZ chip to support the RS-485 interface and power stabilizers for photodetectors and light sources, a reference voltage source for light sources, made on the TL431 chip, as well as passive filters, indicator with vediodes and other elements.

The electrical connections of the optical sources and the control device are made by MGTF mounting wires with a current-carrying core diameter of 0.07 mm and 0.2 mm. The conductors are connected by soldering, which does not require connectors that occupy space.

In the upper part of the optical unit, two RS-4 connectors are installed for connecting a cable connecting the immersion unit and the control and processing unit. One of the connectors is intended for connecting a control module, the second for a temperature sensor, so as not to burden the control module with additional functions for signal transmission. Connectors provide convenience when adjusting the optical module, eliminating the need for working with a bulky working connecting cable. During the operation of the fluorimetric complex, the cable passes inside the cable pipe above the surface of the water; a sealing seal is made near the pipe exit. The seal was made using plastic inserts and filled with a compound like Vixint PK-68. The seal is designed to prevent air exchange of the internal cavity of the immersion unit with the atmosphere in order to avoid the formation of condensate. Above the pipe ending with a fitting, the cable runs inside a flexible silicone hose. The use of a hose instead of rigid pipes reduces the cost and facilitates the installation of a sensor.

The control and processing unit is made using a standard plastic housing for electronic equipment G218. It contains: a battery G 12 - 2.3 with a voltage of 12 V and a capacity of 2.3 Ah (9), electrical connectors, indication elements and a control module made in the form of a printed circuit board. The control module of the base unit of the fluorometric complex contains electronic keys for supplying power to 4 connectors for connecting sensors, RS-485 interface support microcircuits, a USB connector with an FT232RQ support microcircuit for transferring data to a computer, and a connector for exchanging data with the modem. A system for monitoring the voltage of the battery and its recharging is provided, for this, the corresponding contacts of the connector of the control and processing unit must be supplied with a DC voltage from 6 to 18 V from any source, including renewable, for example, from a solar battery.

When debugging a fluorimetric complex, a laptop computer connected using a USB cable is used. In stand-alone mode, data is transmitted over the air using the GSM / GPRS modem SprutNet, RS232 / RS485 (10). The operation of the control module and the entire base unit is controlled by the ATMega324A microcontroller. On the control module board, surface-mounted electronic components are predominantly used.

The software for all microcontrollers of the fluorimetric complex was developed in the Assembler for AVR language in the AVR Studio environment; the AVR Dragon programmer was used to download programs to the microcontrollers. During operation of the complex, the control and processing unit includes, once every 5 minutes, in turn the optical module of the submersible unit and the temperature sensor separately inside it. The measurement results of all photodetectors are normalized to the result of the control photodetector in the optical module control device and transmitted to the control and processing unit, in which the measured values are already calculated taking into account calibration coefficients.

The described implementation of the utility model was set up, including debugging of electronic devices, selection of amplification factors and bandwidths, debugging of firmware, alignment of optical devices, debugging of data transfer, calibration of the complex using aqueous media with known parameters measured by standard means or specially prepared to obtain the required parameters, entering calibration coefficients into the program for processing results. Tests have confirmed the achievement of a solvable utility model problem.

Information sources

1. Patent US 4293225, IPC G01N 21/64 (2006.01), 1981.

2. Patent US 5350922, IPC G01N 21/49 (2006.01), 1994.

3. RF patent No. 2354958 for the invention, IPC G01N 21/64 (2006.01), 2006.

4. Patent US 6020587 A, IPC G01N 21/35 (2006.01), 2000.

Claims (5)

1. A fluorimetric complex containing one or more pulsed or continuous optical sources of excitation of intravital fluorescence of phytoplankton, a photodetector of a fluorescence signal, a photodetector for recording the intensity of the excitation signal, allowing to take into account the instability of the exciting light and correct the measurement results, characterized in that it contains at least one additional light receiver in the excitation band, which detects radiation scattered by the aqueous medium, due to mu simultaneously with the content of phytoplankton determines the content of total suspended matter. 2. The complex according to claim 1, characterized in that for separate registration of chlorophyll fluorescence corresponding to the response of photosystem I and the response of photosystem II, it contains 2 photodetectors of the fluorescence signal, one of which receives only fluorescence in the spectral band including the band 680-695 nm and not including the band 720-750 nm, and the second only accepts fluorescence in the spectral band including the band 720-750 nm and not including the band 680-695 nm. 3. The complex according to claim 1, characterized in that it contains an additional thermal sensor for simultaneously measuring the temperature of the aqueous medium. 4. The complex according to claim 1, characterized in that it contains an additional photodetector for detecting the background illumination of the aquatic environment, allowing to take into account the influence of natural or artificial light on the state of the photosynthetic apparatus of the chlorophyll phytoplankton. 5. The complex according to claim 1, characterized in that it has an autonomous power supply, and the measurement results are transmitted over the air.

Images