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WO2019043408A1 - Dispositif de mesure d'absorption de chlorophylle - Google Patents

Dispositif de mesure d'absorption de chlorophylle Download PDF

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Publication number
WO2019043408A1
WO2019043408A1 PCT/GB2018/052485 GB2018052485W WO2019043408A1 WO 2019043408 A1 WO2019043408 A1 WO 2019043408A1 GB 2018052485 W GB2018052485 W GB 2018052485W WO 2019043408 A1 WO2019043408 A1 WO 2019043408A1
Authority
WO
WIPO (PCT)
Prior art keywords
meter
wavelength
sample
light
wavelengths
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/GB2018/052485
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English (en)
Inventor
William NIMMO-SMITH
Giorgio DALL'OLMO
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
PLYMOUTH MARINE LABORATORY
Plymouth University
Original Assignee
PLYMOUTH MARINE LABORATORY
Plymouth University
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by PLYMOUTH MARINE LABORATORY, Plymouth University filed Critical PLYMOUTH MARINE LABORATORY
Publication of WO2019043408A1 publication Critical patent/WO2019043408A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
    • G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
    • G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
    • G01N21/314—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry with comparison of measurements at specific and non-specific wavelengths
    • G01N21/3151—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry with comparison of measurements at specific and non-specific wavelengths using two sources of radiation of different wavelengths
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
    • G01J3/00—Spectrometry; Spectrophotometry; Monochromators; Measuring colours
    • G01J3/28—Investigating the spectrum
    • G01J3/42—Absorption spectrometry; Double beam spectrometry; Flicker spectrometry; Reflection spectrometry
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
    • G01J3/00—Spectrometry; Spectrophotometry; Monochromators; Measuring colours
    • G01J3/28—Investigating the spectrum
    • G01J3/42—Absorption spectrometry; Double beam spectrometry; Flicker spectrometry; Reflection spectrometry
    • G01J3/427—Dual wavelengths spectrometry
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
    • G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
    • G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
    • G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
    • G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
    • G01N21/314—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry with comparison of measurements at specific and non-specific wavelengths
    • G01N2021/3181—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry with comparison of measurements at specific and non-specific wavelengths using LEDs
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/84—Systems specially adapted for particular applications
    • G01N2021/8466—Investigation of vegetal material, e.g. leaves, plants, fruits
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2201/00—Features of devices classified in G01N21/00
    • G01N2201/06—Illumination; Optics
    • G01N2201/062—LED's

Definitions

  • the present invention relates generally to a sensor and particularly to a meter that measures chlorophyll-a concentration (Chi) with a much greater accuracy than existing field instruments.
  • Phytoplankton Although invisible to the human eye, microscopic algae free-floating in the ocean (phytoplankton) provide indispensable ecosystem services to the human population. Phytoplankton sustain the oceanic food web and ultimately the marine proteins upon which we rely [6]. Phytoplankton are marine plants that photosynthesise and in doing so produce half of the oxygen we breath [6]. Phytoplankton are also the first crucial component of the ocean biological carbon pump, which transfers carbon from the surface to the ocean interior and ultimately lowers atmospheric C0 2 concentration by approximately 50% [ 1 3]. To understand how these critical ecosystem services may be affected by environmental and climatic variability, we need to monitor the current distribution and variability of microscopic algae.
  • Phytoplankton biomass has traditionally been quantified as the concentration of chlorophyll-a (Chi), which is the only photosynthetic pigment ubiquitous in all marine algae. Chi is also used to estimate net primary production (the rate at which solar energy is converted into chemical energy and made available to the ecosystem, [6]) and the eutrophication status of both marine and inland waters.
  • Chi chlorophyll-a
  • phytoplankton biomass has been selected as an Essential climate Variable by the steering committee for Global climate Observing System. It is therefore crucial to sustain accurate observations of phytoplankton Chi. However, accurate in-situ observations are laborious and expensive and thus relatively limited in space and time.
  • F depends also on the composition of phytoplankton that are measured (e.g. diatoms vs. picoplankton) and the Chl:F ratio can vary by nearly six fold across different phytoplankton cultures [ 14].
  • Chl:F ratio can vary by nearly six fold across different phytoplankton cultures [ 14].
  • the present invention seeks to address the above limitations and provide an instrument for accurately and automatically measuring Chi in situ both in the field and in the laboratory.
  • the present invention is based on analyses of data collected under diverse open-ocean regimes using a commercial instrument (ACs) [2, 3, 4, 1 5, 1 7, I ]. Results from the analysis of one of these datasets are presented in Figure I to demonstrate that the current algorithm used to estimate chlorophyll concentration in the field (ALGO I ) is highly accurate (top left plot). This is because ALGO I is based on highly-accurate particulate absorption measurements, that are obtained by subtracting from bulk absorption measurements a baseline signal determined using filtered seawater. This baseline correction greatly improves the stability of the ACs output. The results also demonstrate that the "packaging effect" [ 1 0] does not degrade the accuracy of ALGO I over the wide range of Chi investigated. In addition, Figure I demonstrates that this algorithm can be considerably simplified while at the same time maintaining its accuracy by using bulk absorption measurements (ALG02, top right plot), provided that the drift in the ACs baseline (bottom plot) is accounted for.
  • the physical principle at the basis of the meter of the present invention is the absorption of light by chlorophyll-a, which is, to first order, directly proportional to Chi.
  • Phytoplankton cells have a broad range of pigments that strongly absorb light in the blue region of the spectrum (i.e. between 400 and 500 nm, Figure 3).
  • chlorophyll-a is unique, because it has a distinct peak of absorption in the red spectral region at about 676 nm ( Figure 3). By measuring the height of this red absorption peak, the concentration of chlorophyll-a can be accurately determined [ I , 2, 3, 4, 17]. This method was first proposed about twenty years ago [5], but was not further developed, tested and applied, probably because the oceanographic community was not familiar with absorption measurements.
  • the meter could be deployed in a continuous flow-through mode on all vessels monitoring freshwater and marine ecosystems. Other areas include monitoring Chi in pools, wastewaters, aquaculture, aquaria, and laboratory environments.
  • the system is flexible enough to allow, with only minor modifications (e.g. by replacing LEDs and interference filters), detection of additional absorbing compounds such the phycobilin pigments.
  • Phycobilins are markers for potentially toxic cyanobacterial blooms which are impacting an increasing number of lakes worldwide. Modifications of the meter could thus have additional applications for the management of environmental resources.
  • the method currently used to accurately estimate Chi in the field is rather complex, because it employs measurements of absorption by suspended particles at three wavelengths to estimate the height of the red-absorption peak (Fig. 3).
  • This particulate absorption has been measured using a system that automatically supplies (for 1 0 minutes every hour) 0.2-um filtered seawater to the ACs instrument (e.g., [2, 1 5]).
  • This filtered seawater is used as a baseline that is then subtracted from the bulk absorption signal to obtain, after correcting for the scattering error [2, 1 5], a highly- accurate estimate of the particulate absorption coefficient (a p ).
  • a p highly- accurate estimate of the particulate absorption coefficient
  • the present invention provides an instrument based on light- emitting diodes (LEDs) and electronics and without moving mechanical parts to provide stability. This stability allows for simplification of the accurate determination of Chi in situ by avoiding the need for the baseline correction derived by measuring filtered seawater.
  • LEDs light- emitting diodes
  • a two-wavelength system is employed.
  • Some of the criteria for meters formed in accordance with the present invention include: required LED power; detector sensitivity; optimal spectral channels; and signal stability.
  • the present invention provides a chlorophyll absorption meter for measuring chlorophyll-a concentration in situ, the meter comprising: an LED for generating a first wavelength in the range of about 670nm to 680nm; an LED for generating a second wavelength in the range of about 685nm to 695nm; a sample chamber for receiving a liquid sample; a sample detector for detecting light at the first and second wavelengths after it is transmitted through a sample; and means for determining light transmittance at the first and second wavelengths.
  • the optical set up is based on two separate LEDs.
  • the light may be collimated and filtered to select wavelengths at 676 ⁇ 5 or ⁇ I and 690 nm ⁇ 5 or ⁇ I .
  • the light may be collimated and filtered to select wavelengths at approximately 676 and 690 nm (Fig. 5) or at exactly 676 nm and 690 nm.
  • a reference detector may be used monitor the input light to the sampling chamber.
  • Collimated light may interact with a sample (such as phytoplankton cells) in a reflective sample chamber and the transmitted signal may be efficiently captured by the sample detector by means of a light diffuser.
  • a sample such as phytoplankton cells
  • Both detectors and LEDs may have dedicated temperature sensors to monitor and correct for potential temperature-related drifts.
  • Optical windows may be machined to allow the reflective tube and sleeves to connect with the main meter body.
  • An electronic board may be provided to switch on the LEDs in an alternating mode, to allow the sample detector to separately measure the light transmitted through the sample in each of the two wavelength ranges.
  • the detectors will also record a signal when the LEDs are off, which will be used to correct for residual ambient stray light and dark currents.
  • a custom-made software may be provided to easily control and operate the system.
  • a reference material e.g., stable coloured glass
  • a given transmittance difference between 676 and 690 nm may be provided, which can be used to monitor the stability of the output signal.
  • the signal from Ch/-free water will be used as a reference.
  • the differences between the recorded transmittance at 676 nm and that at 690 nm may be used as a proxy to Chi, as shown for ALG02 in Fig. I .
  • the second wavelength is used as a reference wavelength.
  • a first LED is used to generate the first wavelength and a second, different LED is used to generate the second wavelength.
  • the first and second LEDs wavelength emissions may be generally centred at the said wavelengths.
  • the present invention uses not only LEDs centred at specific wavelengths, but also with added interference filters between the LEDs and the sample to restrict the band width of each emission.
  • An interference filter may be provided for each LED emitter to restrict the bandwidth.
  • a miniaturised, water-tight and depth-rated version of the instrument may be provided.
  • a further aspect provides a marine vessel provided with one or more meters as described herein.
  • a further aspect provides a method for measuring chlorophyll-a concentration in situ, the method comprising: generating a first wavelength in the range of about 670nm to 680nm; generating a second wavelength in the range of about 685nm to 695nm; providing a liquid sample; detecting light at the first and second wavelengths after it is transmitted through the sample; determining light transmittance at the first and second wavelengths; and determining the difference between the light transmittance values at the first and second wavelengths.
  • Figure I Relationships between estimates of Chi from HPLC and in-situ absorption- based algorithms for a dataset collected during an Atlantic Meridional Transect cruise. Top left: standard ACs algorithm based on measurements of the particulate absorption coefficients at three wavelengths (ALGO I ); Top right: algorithm to be applied to the measurements of bulk absorption measurements at two wavelengths (ALG02). Data used for computing ALG02 have been corrected for the significant drift in the baseline of ACs instrument (bottom plot).
  • Figure 3 Typical particulate absorption spectrum (green) measured with and ACs instrument. The peak due to chlorophyll-a at about 676 nm is clearly visible. Dashed lines provide a graphical explanation for the current Chi algorithm that is applied to ACs absorption spectra (ALGO I ).
  • Figure 4 Relationships between estimates of Chi based on ACs absorption (red circles) and fluorescence (blue squares) data versus HPLC-based total Chi from discrete samples collected during an AMT cruise (modified from [4]). While absorption was transformed into Chi by applying a constant conversion factor taken from the literature, fluorescence data were "calibrated" by means of discrete measurements during the cruise. Thus, even if F is calibrated it is an inaccurate measure of Chi. Thus have additional applications for the management of environmental resources.
  • Figure 5 Example optical design of a meter, including two different LEDs.
  • the two LEDs provide fixed light emission wavelength sources at specific wavelengths which are restricted to a relatively narrow range.
  • LEDs centred at specific wavelengths are used and in addition interference filters are used to restrict the band width of each emission.

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  • Physics & Mathematics (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Health & Medical Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Toxicology (AREA)
  • Investigating Or Analysing Materials By Optical Means (AREA)
  • Investigating, Analyzing Materials By Fluorescence Or Luminescence (AREA)

Abstract

L'invention concerne un dispositif de mesure d'absorption de chlorophylle permettant de mesurer une concentration de chlorophylle-a in situ. Ledit dispositif de mesure comprend : une DEL permettant de générer une première longueur d'onde dans une plage environ de 670 nm à 680 nm ; une DEL permettant de générer une seconde longueur d'onde dans une plage environ de 685 nm à 695 nm ; une chambre d'échantillon permettant de recevoir un échantillon liquide ; un détecteur d'échantillon permettant de détecter la lumière à la première longueur d'onde et à la seconde longueur d'onde après son émission à travers un échantillon ; et un moyen de détermination de la transmittance de lumière à la première longueur d'onde et à la seconde longueur d'onde.
PCT/GB2018/052485 2017-09-01 2018-09-03 Dispositif de mesure d'absorption de chlorophylle Ceased WO2019043408A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB1714042.7A GB2566064A (en) 2017-09-01 2017-09-01 Chlorophyll absorption meter
GB1714042.7 2017-09-01

Publications (1)

Publication Number Publication Date
WO2019043408A1 true WO2019043408A1 (fr) 2019-03-07

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PCT/GB2018/052485 Ceased WO2019043408A1 (fr) 2017-09-01 2018-09-03 Dispositif de mesure d'absorption de chlorophylle

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WO (1) WO2019043408A1 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN108152234A (zh) * 2018-02-26 2018-06-12 中国科学院南京地理与湖泊研究所 一种湖泊藻类色素浓度快速监测装置
JP2021014991A (ja) * 2019-07-10 2021-02-12 国立研究開発法人農業・食品産業技術総合研究機構 クロロフィル含有量の測定方法及び果実の熟度判定方法

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5424840A (en) * 1992-07-21 1995-06-13 The State Of Oregon Acting By And Through The State Board Of Higher Education On Behalf Of Oregon State University In situ chlorophyl absorption meter
WO2013188952A1 (fr) * 2012-06-21 2013-12-27 Honeywell Asca Inc. Détecteur pour la détection précoce de problèmes dans des cultures d'algues, et système et procédé associés

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104777108B (zh) * 2015-02-04 2018-01-19 中国农业大学 一种叶绿素含量的检测装置及方法

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5424840A (en) * 1992-07-21 1995-06-13 The State Of Oregon Acting By And Through The State Board Of Higher Education On Behalf Of Oregon State University In situ chlorophyl absorption meter
WO2013188952A1 (fr) * 2012-06-21 2013-12-27 Honeywell Asca Inc. Détecteur pour la détection précoce de problèmes dans des cultures d'algues, et système et procédé associés

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
C MOORE ET AL: "Optical tools for ocean monitoring and research", OCEAN SCIENCE, 10 December 2009 (2009-12-10) - 2009, pages 661 - 684, XP055520262, Retrieved from the Internet <URL:https://www.ocean-sci.net/5/661/2009/os-5-661-2009.pdf> [retrieved on 20181030], DOI: 10.5194/os-5-661-2009 *

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN108152234A (zh) * 2018-02-26 2018-06-12 中国科学院南京地理与湖泊研究所 一种湖泊藻类色素浓度快速监测装置
CN108152234B (zh) * 2018-02-26 2024-09-06 中国科学院南京地理与湖泊研究所 一种湖泊藻类色素浓度快速监测装置
JP2021014991A (ja) * 2019-07-10 2021-02-12 国立研究開発法人農業・食品産業技術総合研究機構 クロロフィル含有量の測定方法及び果実の熟度判定方法
JP7360649B2 (ja) 2019-07-10 2023-10-13 国立研究開発法人農業・食品産業技術総合研究機構 クロロフィル含有量の測定方法及び果実の熟度判定方法

Also Published As

Publication number Publication date
GB2566064A (en) 2019-03-06
GB201714042D0 (en) 2017-10-18

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