RU94335U1 - SUBMERSIBLE PROBE FOR DETERMINING HYDROPHYSICAL AND HYDROCHEMICAL PARAMETERS OF WATER IN WATER BODIES - Google Patents

Abstract

 An immersion probe for determining the hydrophysical and hydrochemical parameters of water in water bodies, including an emitter and a radiation receiver, characterized in that an LED is used as an emitter, and a photodiode is used as a radiation receiver, in addition, two more LEDs are additionally included in the device, all three LEDs connected through a current stabilizer to a power source and installed on the side of the Secchi disk, which when placing the Secchi disk in a pond using a device that can be in filled in the form of a rod or rope with a linear scale with divisions, facing the bottom of the reservoir, in addition, at a certain distance from each LED there is a corresponding photodiode coaxially along the optical axes of these LEDs and photodiode, which are registered to the photodiode through a corresponding variable resistor the device forms a photometric channel, and the photometric channels corresponding to three LEDs are used to determine suspended particles, indicate the content of phytoplankton, p soluble organic substances, and on the other side of Secchi's disk there is a fourth photodiode, which, with a recording device connected to it through a variable resistor, forms a photometric channel designed to detect illumination in the water column, and an LED with a spectral range of radiation is made as one of the three LEDs 640-670 nm and with a maximum of 660 nm (red), another LED is made with a spectral range of 510-550 nm and a maximum of 535 nm (green), as

Description

The utility model is intended for joint simultaneous determination of transparency, turbidity, color of water, indication of phytoplankton content and illumination at a depth of up to 2.5 m in natural reservoirs.

Known "Marine turbidimeter" according to patent RU2112232, which contains a housing, a series of turbidimetric channels, each of which is made in the form of a reference voltage source and connected in series with a modulator and a red light source, optically coupled to a photodetector, which is connected in series with a photo current amplifier and a demodulator, the control input of which is connected to the synchronization output of the modulator, a number of strain gauge channels, a processing unit and an indication unit.

The main disadvantage of this device is that it measures only the content of suspended particles in water.

The invention is known "Two-beam photometer" according to patent RU2169360, selected as a prototype, which contains a sealed container in which the emitter is placed and the collimator, beam splitter, chopper of radiation beams, porthole, optical path unit of the reference and measuring radiation beams located in series in the studied environment and made in the form of two retroreflective prisms, a light-reducing device, a lens and a radiation receiver.

This two-beam photometer does not allow measuring the transparency of water and the illumination in its thickness. In addition, it contains a number of optical units that are expensive, complex to perform and operate (a beam splitter, an optical path unit, and a chopper).

The task to which the utility model is directed is to expand the capabilities of the device while simplifying it, reducing the cost and reducing the weight of the device.

The problem is solved due to the technical result, which consists in the simultaneous measurement of transparency, turbidity, color of water, an indication of the content of phytoplankton and illumination at a depth of up to 2.5 m in natural reservoirs, provided that the reliability of the proposed device when conducting measurements in the field is increased.

This result is achieved by the fact that in the immersion probe, which includes the emitter and the light emitting receiver, an LED is used as an emitter, and a photodiode is used as a radiation receiver, in addition, two more LEDs are additionally included in the device, all three LEDs being connected through a current regulator to the power source and are installed on the side of the Secchi disk, which when placing the Secchi disk in a pond with the help of a device that can be made in the form of a rod or rope with applied lin with its own scale, it faces the bottom of the reservoir, in addition, at a certain distance from each LED, there is a corresponding photodiode coaxially along the optical axes of these LEDs and the photodiode, which, with a recording device connected to the photodiode through a variable resistor, form a photometric channel; The photometric channels corresponding to the three LEDs are used to determine suspended particles, indicate the content of phytoplankton, soluble organic substances, and on the other side of the Secchi disk there is a fourth photodiode, which, with a recording device connected to it through a variable resistor, forms a photometric channel designed to register illumination in the water column In this case, an LED with a spectral range of radiation of 640-670 nm and with max. with a minimum of 660 nm (red), as another of them, an LED with a spectral range of 510-550 nm and a maximum of 535 nm (green) was used, as a third, an LED with a spectral range of 430-460 nm and a maximum of 450 nm ( blue), and photodiodes with a spectral sensitivity range of 400-1000 nm were used as photodiodes.

Figure 1 shows a General view of an immersion probe for determining the hydrophysical and hydrochemical parameters of water in reservoirs, Figure 2 shows a functional diagram of an immersion probe, Figure 3 shows a view of the part of the probe immersed in a reservoir facing the bottom of the reservoir. On these figures are indicated: 1 - a bar with a scale, 2 - a disk of a waterproof material of white color (Secchi disk); 3 - light sensor (fourth photodiode); 4 - a block of emitters (circled by a dashed line) with LEDs 5, 6, 7; 8 - a block of radiation receivers (circled by a dot-dash line) with photodiodes 9, 10, 11; 12 - registration unit (circled by a double dash-dot line), which includes: 13 - an autonomous power source for LEDs; 14 - current stabilizer for LEDs; 15 - brightness control of emitters (LEDs); 16, 18, 20 - variable resistors for regulating the output signals from radiation receivers (photodiodes) 9, 10, 11; 17, 19, 21 - recording devices, for example, pointer microammeters.

To measure the illumination in the water column, the device comprises a measuring channel, consisting of a light sensor (fourth photodiode 3), a tuning resistor 22, and a recording device 23.

In the device, a Secchi disk of white waterproof material is held in water by means of a device that can be made in the form of a rod 1 or a rope with a linear scale. Transparency is determined visually by the divisions on the device bar.

Prior to measurements, the immersion probe is calibrated. To do this, with the help of a bar with a scale of 1, it is immersed in water. When connecting the connector of the registration unit 12 to the connector of the immersion unit from the power source (battery) 13 through the current stabilizer 14 and the brightness control of the emitters 15, power is supplied to the LEDs 5, 6, 7. The current stabilizer 14 ensures a constant current supply of the LEDs 5, 6, 7, which form light fluxes directed to photodiodes 9, 10, 11. Variable resistors 16, 18, 20 set the maximum values of the photocurrent recorded by microammeters 17, 19, 21 when the LEDs 5, 6, 7 are connected to an autonomous power source I 13 through the current stabilizer 15. The photovoltaic currents of the photodiodes 9, 10, 11 through the tuning resistors for regulating the output signals 16, 18, 20 are recorded with microammeters 17, 19, 21. LED 5, the photodiode 9, the tuning resistor 16 and the recording device 17 forms the first measuring channel, LED 6, photodiode 10, trimming resistor 18 and the recording device 19 forms a second measuring channel, LED 7, photodiode 11, trimming resistor 20 and the recording device 21 form a third measuring channel . To calibrate the values of the recording devices 17, 19, 21, the immersion probe is placed in calibration solutions containing a certain known amount of each specific component. Changing the concentration of dissolved organic substances (DOM), algae, suspended particles produce calibration. An immersion probe is placed in the test water. The values of the photocurrent corresponding to certain calibration values determine the content of the components in the test water.

The calibration of the light sensor (fourth photodiode) 3 is carried out in daylight by recording the value of the photocurrent using a light meter sensor.

Illumination is determined using calibration data on the value of the photocurrent of the illumination determination channel, consisting of a photodiode 3, a tuning resistor 22, and a recording device 23.

Definition of transparency:

Transparency is determined visually by the divisions on the device bar using the Secchi disk.

For the joint determination of suspended particles, dissolved organic matter (DOM) and indication of phytoplankton, LEDs and photodiodes are combined into blocks of emitters and radiation detectors.

Determination of suspended particles.

LED 5 of the first measuring channel emits 510-550 nm green light with a maximum of 535 nm. In this spectral range, there is a minimum absorption by both chlorophyll and dissolved organic matter (DOM), therefore, the absorption of light will be due only to non-selective scattering by suspended particles. Thus, the first measuring channel registers the content of suspended particles in the water.

To determine the content of suspended particles, the photocurrent values of the first measuring channel are used and according to the formula:

s _in = I ₀ -I ₃

determine the value of the analytical signal S _in to determine the content of suspended particles in μA, where:

I ₀ is the value of the photocurrent of the measuring channels for pure water;

I _C - the value of the photocurrent of the green radiation channel in the recording device 17.

The values of the analytical signal S _in , corresponding to certain calibration data, determine the content of suspended particles in the test water.

Determination of phytoplankton content.

LED 6 of the second measuring channel emits red light of 640-670 nm with a maximum of 660 nm. In this spectral range, a minimum of absorption by dissolved organic matter (DOM) is observed, but a maximum of phytoplankton absorption by chlorophyll; therefore, the absorption of light will be due to the sum of non-selective scattering by suspended particles and absorption of radiation by chlorophyll. Thus, the second measuring channel registers the sum of suspended particles in water and phytoplankton.

To determine the content of phytoplankton use the values of the photocurrent of the second measuring channel and according to the formula

S _f = I ₀ -S _to -I _to

determine the value of the analytical signal S _f to determine phytoplankton in μA, where:

I ₀ is the value of the photocurrent of the measuring channels for pure water;

I _to - the value of the photocurrent of the red radiation channel in the recording device 19;

s _in - analytical signal for determining the content of suspended particles, μA.

The values of the analytical signal S _f corresponding to certain calibration data, which are determined by the types of algae that are characteristic of the controlled water body, determine the content of phytoplankton in the studied water.

Determination of dissolved organic matter (DOM).

LED 7 of the third measuring channel emits a blue-violet color of 430-460 nm with a maximum of 450 nm. In this spectral range, there is a maximum absorption by dissolved organic matter (DOM), a maximum absorption of phytoplankton by chlorophyll and non-selective scattering by suspended particles is maintained, therefore, the absorption of light will be due to the sum of non-selective scattering by suspended particles, absorption of radiation by chlorophyll and absorption of radiation of DOM. Thus, the third measuring channel registers the sum of suspended particles in water, phytoplankton and DOM.

The content of DOM is determined using calibration data from the value of the analytical signal S _p in μA, calculated by the formula:

S _p = I ₀ -S _to -2.7S _f -I _c ,

Where:

I ₀ is the value of the photocurrent of the measuring channels for pure water;

S _in - analytical signal for determining the content of suspended particles, µA;

S _f - analytical signal for determining phytoplankton, μA;

I _c is the photocurrent value of the blue radiation channel;

For research, an immersion probe was made to determine the hydrophysical and hydrochemical parameters of water in water bodies, in which Luxeon low-aperture LEDs were used as LEDs. BPX90 photodiodes were used as photodiodes, having a spectral sensitivity range of 400-1100 nm, placed in an FD-263-01 package with a lens. The cases are sealed with Moment sealant TU 2257-018-0483 1040-2001. Blocks of emitters and radiation receivers are fixed at the bottom of a circle of duralumin with a diameter of 300 mm and a thickness of 5 mm and are located coaxially along the optical axes of the LEDs and photodiodes (Figure 3.). The photodiode was located on top of a duralumin disk and was used in photovoltaic mode.

To determine the suspended particles, we used the radiation of a low-aperture Luxeon LED with a spectral range of 510-550 nm with a maximum of 535 nm (green glow). These characteristics correspond to the minimum absorption of other components. Due to the scattering of radiation, suspended particles caused a decrease in the signal installed in distilled water in the entire spectral range (the so-called non-selective absorption)

To determine chlorophyll, we used the radiation of a low-aperture Luxeon LED with a spectral range of radiation of 640-670 nm with a maximum of 660 nm. The most important feature of the absorption spectrum of chlorophyll "a" and "b" is the presence of two pronounced maxima in them: in the red, respectively, at 660-640 nm and in the blue-violet regions of the spectrum at 420-450 nm. Of greatest interest to us was chlorophyll "a", which has two absorption maxima - at 660 nm in the red region and at 420 nm in the violet region. The absorption band width in the red region was ~ 30 nm, and in the violet region, about 50 nm. Thus, spectrophotographs of 645–675 nm and 405–445 nm were suitable for chlorophyll photometry.

To determine the DOM, we used the radiation of the low-aperture Luxeon Royal Blue LED with a spectral range of 430-460 nm with a maximum of 450 nm. Dissolved Organic Matter (DOM) is a mixture of colored organic compounds. The absorption spectrum was a smooth descending hyperbola in the range of 400–700 nm; the maximum absorption coefficients were located in the range of 400–450 nm.

Claims (1)

An immersion probe for determining the hydrophysical and hydrochemical parameters of water in water bodies, including an emitter and a radiation receiver, characterized in that an LED is used as an emitter, and a photodiode is used as a radiation receiver, in addition, two more LEDs are additionally included in the device, all three LEDs connected through a current stabilizer to a power source and installed on the side of the Secchi disk, which when placing the Secchi disk in a pond using a device that can be in made in the form of a rod or rope with a linear scale with divisions, facing the bottom of the reservoir, in addition, at a certain distance from each LED there is a corresponding photodiode aligned with the optical axes of these LEDs and photodiode, which register the device forms a photometric channel, and the photometric channels corresponding to three LEDs are used to determine suspended particles, indicate the content of phytoplankton, p soluble organic substances, and on the other side of Secchi's disk there is a fourth photodiode, which, with a recording device connected to it through a variable resistor, forms a photometric channel designed to detect illumination in the water column, and an LED with a spectral range of radiation is made as one of the three LEDs 640-670 nm and with a maximum of 660 nm (red), another LED is made with a spectral range of 510-550 nm and a maximum of 535 nm (green), as The third LED is made with a spectral range of 430-460 nm and a maximum of 450 nm (blue), and photodiodes are made with photodiodes with a spectral range of sensitivity of 400-1000 nm.