WO2006103932A1

WO2006103932A1 - Plant plankton distribution measuring method and device therefor

Info

Publication number: WO2006103932A1
Application number: PCT/JP2006/305142
Authority: WO
Inventors: Hidekatsu Yamazaki
Original assignee: National University Corporation Tokyo University Of Marine Science And Technology
Priority date: 2005-03-29
Filing date: 2006-03-15
Publication date: 2006-10-05
Also published as: JPWO2006103932A1; JP4904505B2

Abstract

A plant plankton distribution measuring device (1) comprising a laser fluorescence probe (7) having a streamline lower end, a laser light emitting section (8) for irradiating pulse laser light having a wavelength for exciting chlorophyll dye from the side face of the probe (7) into the water, and a light receiving section (9) for detecting fluorescence entering through the side face of the probe (7). The distribution measuring device (1) is dropped into the water, laser light irradiating direction of the laser light emitting section (8) is made to intersect the light receiving region of the light receiving section (9), fluorescence being emitted from plant planktons upon receiving the pulse laser light is received at the light receiving section (9), and then the quantity of plant planktons is measured based on the quantity of received light.

Description

Specification

Phytoplankton distribution measuring method and apparatus

Technical field

TECHNICAL FIELD [0001] The present invention relates to a phytoplankton distribution measurement method and apparatus for measuring a phytoplankton distribution by allowing a measuring device to freely fall in water.

Background art

[0002] With the warming of seawater, phytoplankton such as dinoflagellates, flagellates, cilia, and diatoms proliferate and red tides that cause great damage to seafood and seaweed frequently occur. Yes. In recent years, the cultivation of seafood has become popular, so it is necessary to know the occurrence of red tide at an early stage and move the seafood.

[0003] For this reason, various types of submerged plankton detectors have been proposed which are thrown into water and allowed to fall freely and measure the actual distribution of phytoplankton in water.

[0004] Conventionally, a light-emitting diode and a light-receiving unit have been provided on the side of the measuring instrument, and light having a wavelength that excites the planktonic dye in water is emitted from the light-emitting diode, and the light emitted from the plankton in water is received by this light. An underwater plankton sensor that receives light and quantifies the amount of underwater plankton based on the amount of received light is known (see Japanese Patent Laid-Open No. 8-15157).

[0005] However, the conventional plankton sensor is formed in a cylindrical shape with the tip surface depressed, so that turbulent flow is generated in the periphery when dropping in the water, and therefore the phytoplankton is disturbed and accurate. I can't measure the correct distribution situation.

[0006] In addition, since the light emitting diode that irradiates diffused light and the light receiving portion that spreads as the light receiving region is moved away from each other are arranged in the sensor unit, it is difficult to accurately limit the measurement region. In addition, the fluorescence emitted by phytoplankton distributed near the sensor unit and the fluorescence emitted by phytoplankton distributed far from the sensor unit are detected, and the measurement result tends to be inaccurate.

[0007] Therefore, in order to limit the measurement area, a light receiving window is provided on the side surface of the detector body, a plurality of light transmitting windows are provided in an annular shape surrounding the light receiving window, and a light emitting diode is provided at the back of the light transmitting window. A fluorescence detector has been proposed in which the light irradiation direction intersects the center line of the light receiving hole. (See JP-A-8-261934).

However, since this fluorescence detector also uses a normal light emitting diode as the light emitting section, the irradiated light diffuses and the area overlapping the light receiving area of the light receiving section (that is, the measurement area) becomes wide. However, the distribution density of phytoplankton in a limited area cannot be accurately measured, and the measurement accuracy is inevitably becoming coarse.

[0009] In addition, since this fluorescence detector is mounted on a cylindrical probe, it is impossible to prevent disturbance of the water flow around the injection point.

Disclosure of the invention

[0010] An object of the present invention is to provide a phytoplankton distribution measurement method and apparatus capable of fine measurement in a state close to nature because the measurement range in which the water flow at the place where the apparatus is introduced is difficult to be disturbed can be narrowly defined. It is to provide.

[0011] The phytoplankton distribution measuring method of the present invention comprises a probe having a streamlined lower end and a laser emitting section and a light receiving section that freely falls in water in an upright state, and is dropped by the laser emitting section during the fall. Irradiating a pulse laser beam having a wavelength for exciting the chlorophyll dye into the water from the side of the probe at an angle crossing the light receiving region of the light receiving unit, and receiving the pulse laser light to emit fluorescence emitted by phytoplankton at the light receiving unit. The amount of phytoplankton is measured based on the amount of light received by the light receiving unit.

[0012] The phytoplankton distribution measuring apparatus of the present invention freely falls in water in an upright state, and has a streamlined probe at the lower end and a pulsed laser beam having a wavelength for exciting a chlorophyll dye from the side of the probe into the water. And a light receiving unit for detecting fluorescence incident on the side surface of the probe, and the direction of laser light irradiation of the laser emitting unit with respect to the light receiving region of the light receiving unit , And the fluorescence emitted from the phytoplankton is received by the light receiving unit in response to the pulsed laser light emitted by the laser emitting unit, and the amount of phytoplankton is measured based on the amount of the received light.

[0013] According to the present invention, since the lower end portion of the probe is streamlined, the water flow at the measurement location is not easily disturbed, so that the distribution of phytoplankton can be measured in a state close to nature, and the measurement accuracy Increase.

[0014] Further, a highly focused pulsed laser beam from the light emitting part intersects the light receiving region of the light receiving part. Therefore, the measurement area can be made very narrow and narrow, and as a result, the distribution of vegetation plankton at each water depth can be meticulously measured.

Brief Description of Drawings

[0015] FIG. 1 is a cross-sectional view of an underwater measuring apparatus incorporating an embodiment of a phytoplankton distribution measuring apparatus according to the present invention.

2 is a cross-sectional view of a phytoplankton distribution measuring device attached to the lower end of the underwater measuring device of FIG.

FIG. 3 is a cross-sectional view of a principal part of the phytoplankton distribution measuring apparatus in FIG. 2.

FIG. 4 is a cross-sectional view of an experimental underwater measurement device equipped with the plant plan distribution measurement device of FIG. 2.

FIG. 5 is a graph showing the change over time in the deviation between the water temperature detected by the water temperature sensor of the experimental underwater measuring device in FIG. 4 and the temperature of the water filled in the water tank.

FIG. 6 is a diagram showing a change with time of the fluorescence intensity detected by the light receiving unit in the phytoplankton distribution measuring device attached to the experimental underwater measuring device of FIG. 4.

FIG. 7 is a diagram showing power spectra of measured temperature (FIG. 5) and fluorescence intensity (FIG. 6). BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

As shown in FIG. 1, the phytoplankton distribution measuring apparatus 1 of the present invention is installed along the axial direction at the lower end of an underwater measuring apparatus 2 that is thrown into water and freely falls. A floating body 3 is mounted on the upper part of the underwater measuring device 2 in order to balance and adjust the descending speed when descending underwater.

[0018] In addition to the distribution measuring device 1, other sensors 4 such as a depth sensor and a thermometer, and a protective rod 5 longer than the distribution measuring device 1 and other sensors 4 are provided at the lower end of the underwater measuring device 2. Can be installed. The protective bar 5 is used to prevent the distribution measuring device 1 and other sensors 4 from colliding with an object during dropping and being damaged. The other sensors 4 and the protective rods 5 are all streamlined so that the surrounding water flow is not disturbed.

As shown in FIG. 2, the phytoplankton distribution measuring device 1 includes a pipe-like support portion 6 attached to the lower end of the underwater measurement device 2, and a laser fluorescent probe attached to the lower end of the support portion 6. The laser fluorescent probe 7 contains a laser light emitting unit 8, a light receiving unit 9, and a control circuit (not shown).

[0020] The laser fluorescent probe 7 is composed of a streamlined cylinder at the lower end, and a light emitting window 1 is formed on the side surface thereof.

0 and the light receiving window 11 are formed side by side. In addition, a laser emitting unit 8 is installed inside the light emitting window 10, and a light receiving unit 9 is installed inside the light receiving window 11.

As shown in FIG. 3, the laser light emitting unit 8 includes a heat radiating housing 12, a laser light emitting element 13, and a condenser lens 14.

[0022] A condensing lens 14 is installed in the light emission window 10 of the laser fluorescent probe 7, a heat dissipating housing 12 is disposed in the back thereof, and a laser light emitting element 13 in the heat dissipating housing 12 provides an irradiation part to the condensing lens 14. It's stored and facing.

[0023] The laser light oscillated by the laser light-emitting element 13 is focused to a diameter of about 2 mm by the condenser lens 14, and the laser light-emitting section 8 emits a pulsed laser light having a peak at a wavelength of 407 nm for exciting the phytoplankton chlorophyll pigment the pulse width 2. 778 X 10- ⁴ seconds, so as to irradiate at Bruno pulse cycle 5. 556 X 10 ⁴ seconds.

The light receiving unit 9 includes a filter 15 and a light receiving element 16. The filter 15 selectively transmits light having a wavelength of 610 nm or more and is placed on the inner surface of the transparent pressure-resistant plastic plate 18 fitted in the light receiving window 11. It is installed toward

[0025] Further, the light receiving area of the light receiving unit 9 is widened away from the light receiving window 11 around the axis a orthogonal to the central axis of the underwater measuring device 2, and the angle of the top of the light receiving area is It is about 20 degrees.

[0026] Then, the pulse laser beam p of a predetermined width irradiated from the laser light emitting unit 8 intersects the light receiving region of the light receiving unit 9, and the intersected region (indicated by the oblique lines in FIG. 3) is measured. Region b.

The laser emission unit 8 is attached to the probe 7 so that the inclination angle can be adjusted with respect to the central axis of the probe 7 (parallel to the central axis of the underwater measuring device 2). Therefore, the crossing angle between the central axis a of the light receiving region of the light receiving unit 9 and the pulsed laser light p emitted from the laser light emitting unit 8 can be changed. As shown in Fig. 3, the direction of irradiation of pulsed laser beam p is probed. When adjusted to approximately 45 ° downward with respect to the center axis of 7, the measurement area b (the area where the light receiving area of the light receiving section 9 and the irradiation area of the laser emitting section 8 intersect) is positioned relatively close to the probe 7. It is possible to prevent accidents such as the pulse laser beam p irradiating human eyes and causing damage when the distribution measuring device 1 is hydraulically lifted. The distance of the measurement region b from the probe 7 can be changed by adjusting the mounting angle of the laser emitting unit 8.

[0028] The distribution of phytoplankton is measured as follows.

[0029] When the underwater measurement device 2 is inserted into the water with the cable 17 attached to the upper end of the floating body 3, the underwater measurement device 2 is placed in an upright state with the phytoplankton distribution measurement device 1 and other sensors 4 down. Naturally falls underwater.

[0030] The pulsed laser beam p transmitted from the laser emission unit 8 during the fall is irradiated obliquely downward into the water from the side surface of the laser fluorescent probe 7.

[0031] Since the chlorophyll pigment of phytoplankton emits fluorescence by excitation light having a wavelength of about 430 nm, the phytoplankton in the irradiation range of the laser emission section 8 receives the pulsed laser beam p and receives the pulsed laser beam p. Fluoresce in the same cycle as.

[0032] The fluorescence emitted upon receiving the phytoplankton force pulsed laser light p distributed in the measurement region b reaches the light receiving window 11 formed on the side surface of the laser fluorescent probe 7. Since the wavelength of the fluorescent light passing through the light receiving window 11 is 677 nm, the light passes through the filter 15 installed on the inner surface of the light receiving window 11 and is detected by the light receiving element 16. Light whose wavelength does not reach 600 nm is blocked by the filter 15 and is not detected by the light receiving element 16.

[0033] The fluorescence detected by the light receiving element 16 is detected by the control circuit, and only the light that flickers in the same cycle as the pulsed laser light P emitted from the laser light emitting unit 8 is identified as the fluorescence to be measured. The control circuit force is also extracted as a signal and quantified by a signal processing computer.

[0034] Since the intensity of the pulsed laser light p emitted from the laser emission unit 8 is constant, the amount of phytoplankton distributed in the measurement range b and the amount of fluorescence emitted by the phytoplankton are proportional. Therefore, the amount of phytoplankton can be measured based on the amount of light received by the light receiving unit 9. [0035] In order to test the resolution of the phytoplankton distribution measuring apparatus 1, the following experiment was performed.

As shown in FIG. 4, a highly sensitive water temperature sensor adjacent to the phytoplankton distribution measuring apparatus 1

19 was attached, and the experimental underwater measuring device 20 was obtained.

[0037] The sensor part of the high-sensitivity water temperature sensor 19 is arranged very close to the estimated measurement position (intersection of the pulse laser irradiation direction of the laser light emitting part 8 and the central axis a of the light receiving part 9). The horizontal distance from the side surface of one fluorescent probe 7 is 10 mm, and it is located 5 mm above the central axial force of the light receiving element 16.

[0038] Aojiru filtered with a 52 micron filter (Daisho Co., Ltd., with barley wakana), 10

Dissolved in 7 liters of water at ° C to prepare lppb green juice solution.

[0039] A water tank of 0.7 m (W) X O. 75 m (H) X 13 m (L) was filled with water at a water temperature of 12.7 ° C, and the green juice solution was charged into the water tank.

[0040] On the upper surface of the water tank, a guide rail is installed along its longitudinal direction, and the experimental underwater measuring device 20 is slidably attached to the guide rail so as to be immersed in water.

[0041] Then, a pulse laser beam p having a wavelength of 407 nm is emitted from the laser light emitting unit 8 to a pulse width of 2.7.

78 X 10- ⁴ sec pulse cycle 5. 556 X 10- ⁴ seconds, and irradiated with the light beam 2 mm. The light receiving element

As 16, one that selectively receives light having a wavelength of 677 nm was installed.

[0042] While moving the experimental underwater measuring device 20 along the guide rail at a speed of lOcmZsec with the lower end in front, the water temperature detected by the high-sensitivity water temperature sensor 19 and the temperature of the water filled in the water tank ( 12. The deviation from 7 ° C) and the fluorescence intensity detected by the light receiving unit 9 were measured. The results are shown in Figs. 5 and 6, respectively, and the power spectra of both are shown in Fig. 7.

[0043] The water temperature of the solution and the distribution of the fluorescent substance in the water tank due to the green juice are almost the same immediately after the addition of the solution.

As apparent from FIGS. 5 and 6, the fluorescence intensity received by the light receiving element 16 and the water temperature measured by the high sensitivity water temperature sensor 19 have a high correlation.

Therefore, the light receiving element 16 is located very close to the sensor portion of the high sensitivity water temperature sensor 19, that is,

The phytoplankton distribution measuring device 1 is extremely useful to measure the fluorescence intensity in a very narrow range at a position very close to itself. From the power spectrum shown in FIG. 7, it can be seen that the resolution of the phytoplankton distribution measuring apparatus 1 is higher than that of the high-sensitivity water temperature sensor 19.

Claims

The scope of the claims

[1] The probe with a streamlined lower end and a laser emitting and receiving unit is allowed to fall freely underwater in an upright state.

Irradiating a panoreth laser beam having a wavelength for exciting a chlorophyll dye by the laser light emitting unit during the fall of the probe into the water from the side surface of the probe at an angle intersecting the light receiving region of the light receiving unit,

Detecting the fluorescence emitted from the phytoplankton by receiving the pulsed laser light with the light receiving unit;

A method for measuring the distribution of phytoplankton, comprising measuring the amount of phytoplankton based on the amount of received light detected by the light receiving unit.

[2] A probe with a streamlined bottom end, falling in an upright position in water,

A laser emitting unit that emits a single pulse laser of a wavelength that excites the chlorophyll dye into the water from the side of the probe;

A side force of the probe, and a light receiving unit for detecting the incident fluorescence,

The light-receiving area of the light-receiving unit intersects the laser light irradiation direction of the laser light-emitting unit, and the light emitted from the plant blankon is received by the light-receiving unit in response to the pulsed laser light emitted from the laser light-emitting unit. Measure the amount of phytoplankton by the amount of light received,

Phytoplankton distribution measuring device.

[3] The laser emission unit is attached to the probe so that the inclination angle of the probe can be adjusted. The phytoplankton distribution measuring apparatus according to claim 2, wherein the distance of the probe force can be adjusted.

[4] The laser light emitting unit is disposed in the probe above the light receiving unit and irradiates pulse laser light obliquely downward, while the light receiving unit has a central axis of the light receiving region. 3. The phytoplankton distribution measuring apparatus according to claim 2, wherein the phytoplankton distribution measuring apparatus is provided in the probe so as to be in a direction orthogonal to a central axis of the probe.