Qualitative and quantitative analysis method for colored dissolved organic matters in water body based on substance absorption and fluorescence spectrum characteristics and application of qualitative and quantitative analysis method

Abstract

The invention provides a qualitative and quantitative analysis method for colored dissolved organic matters in a water body based on substance absorption and fluorescence spectrum characteristics and application, and relates to the technical field of detection of the colored dissolved organic matters in the water body. The method comprises the following steps: constructing an excitation and emission spectrum by using an excitation wave band of 230-290 nm and an emission wave band of 340-440 nm; the method comprises the following steps: selecting standard substances of an ocean source, an endogenous source and a terrestrial source, establishing a standard spectrum library, then qualitatively measuring a sample, diagnosing the source of the colored dissolved organic matters, and quantitatively measuring the sample to obtain the concentration of the colored dissolved organic matters of the terrestrial source, the endogenous source and the ocean source, and by adopting the method, the source of the CDOM can be quickly diagnosed, and the composition content of the CDOM can be obtained. The operation is simple, the water sample cannot be damaged, and the accuracy is high.

Description

Technical Field

[0001] The present invention relates to the technical field of detecting chromophoric dissolved organic matter in water bodies, and in particular to a method and application for qualitative and quantitative analysis of chromophoric dissolved organic matter in water bodies based on the absorption and fluorescence spectral characteristics of substances. Background Art

[0002] Chromophoric dissolved organic matter (CDOM) is a mixture of high-molecular-weight compounds with unknown structures in water bodies, composed of polymers of aliphatic and aromatic groups. It is the optically active part of dissolved organic matter (DOM) and together with plankton and suspended sediment constitutes the three major components affecting water color. The optical properties of CDOM are relatively regular, mainly absorbing ultraviolet and visible light, which has an important impact on the light absorption and utilization of water bodies, and can change biochemical processes such as the underwater light field and the primary productivity of aquatic plants, playing an important role in marine and global ecosystems. CDOM is the luminescent part of DOM, and inversion can be used to trace the concentration of DOC in water bodies, thereby explaining the geophysical and chemical carbon cycle process.

[0003] The sources of CDOM in water bodies are mainly divided into exogenous and endogenous. The generation, migration and transformation of endogenous CDOM are closely related to the reproduction and metabolism of organisms in the water environment, mainly including the degradation of phytoplankton and bacterial organisms, and the secretions of planktonic bacterial cells, etc.; exogenous factors are mainly composed of the runoff input formed by domestic pollution and soil organic matter carried by water body runoff. Therefore, CDOM can not only characterize the content of organic matter and the level of biological activity in water bodies, thus reflecting the degree of water quality pollution, but also record the changes in the water body environment caused by human activities (such as deforestation, large-scale mechanical farming, mining, irrigation, building dams, inter-basin water transfer, and urbanization, etc.). Therefore, analyzing the main sources and content of CDOM has significant environmental significance for the prevention and control of organic matter pollution in water bodies.

[0004] At present, the main monitoring methods for pollutants of water body dissolved organic matter are: gas chromatography, liquid chromatography, and ion chromatography. Each detection method has its own advantages and disadvantages. For example, liquid chromatography has a large measurable range and high stability, but the experimental operation is complex and requires more reagents; gas chromatography can classify mixed substances well, but it cannot quickly and non-destructively reflect the changes of substances therein, and these are all laboratory methods and cannot achieve in-situ monitoring; at the same time, different substances have different types and properties, and the detection means are not the same, and for different concentrations, the detection conditions of chromatography and mass spectrometry must be adjusted.

[0005] In view of this, the present invention is specifically proposed. Summary of the Invention

[0006] One of the objectives of the present invention is to provide a qualitative and quantitative analysis method for chromophoric dissolved organic matter in water based on the absorption and fluorescence spectral characteristics of substances, so as to solve at least one of the technical problems existing in the prior art. The qualitative and quantitative analysis method for chromophoric dissolved organic matter (CDOM) in water provided by the present invention can quickly diagnose the source of CDOM and obtain the composition content of CDOM. This method is simple to operate, does not damage the water sample, and has a high accuracy rate.

[0007] Another objective of the present invention is to provide an application of the qualitative and quantitative analysis method for chromophoric dissolved organic matter in water based on the absorption and fluorescence spectral characteristics in water quality monitoring.

[0008] In order to achieve the above objectives of the present invention, the following technical solutions are specifically adopted:

[0009] In the first aspect, the present invention provides a qualitative and quantitative analysis method for chromophoric dissolved organic matter in water based on the absorption and fluorescence spectral characteristics, including the following steps:

[0010] Construct an excitation and emission spectrum with an excitation band of 230 - 290 nm and an emission band of 340 - 440 nm, select standard substances of marine origin, endogenous origin, and terrestrial origin, establish a standard spectral library, and then conduct qualitative measurement and quantitative measurement on the sample;

[0011] Among them, the qualitative measurement includes: measuring the excitation and fluorescence spectra of the actual water body, comparing with the standard spectrum, finding the characteristic spectrum, and diagnosing the source of chromophoric dissolved organic matter; the quantitative measurement includes: analyzing with the established standard spectral library as the independent variable and the actual water body spectrum as the dependent variable to obtain the concentrations of chromophoric dissolved organic matter of terrestrial origin, endogenous origin, and marine origin.

[0012] Further, in the optical path construction, the excitation band includes at least one of 230 nm, 245 nm, 260 nm, 275 nm, and 290 nm.

[0013] Further, in the optical path construction, the emission band includes at least one of 340 nm, 370 nm, 400 nm, and 440 nm.

[0014] Further, in the qualitative measurement of the sample, the source of chromophoric dissolved organic matter is judged by calculating the similarity index SI between the actual water body spectrum and the standard spectrum.

[0015] Further, the calculation formula of the similarity index SI is as follows:

[0016]

[0017] Among them, A1 represents the actual water body spectrum, and A2 represents the standard spectrum.

[0018] Furthermore, SI is greater than or equal to 0 and less than or equal to 1, and the similarity between the actual water spectrum and the standard spectrum is proportional to the value of SI.

[0019] Furthermore, in the quantitative measurement of the sample, a multivariate linear regression analysis is performed on the actual water spectrum, and the formula is as follows:

[0020]

[0021] Where M is the spectral data of the actual water body, f i is a standard fluorescence spectrum library of a standard organic substance, a i is the concentration of a certain standard organic substance, x represents the minimum iteration error, k mn It is the normalized fluorescence intensity of a standard organic substance at the excitation wavelength n and emission wavelength m.

[0022] Furthermore, humic acid, tryptophan and fulvic acid were used as standard substances for marine humus, endogenous protein and terrestrial humus, respectively.

[0023] Furthermore, the process of constructing the optical path includes: ultraviolet band LEDs emit excitation light, and after passing through the beam splitter, part of the light hits the first photodiode for feedback of the light intensity of the ultraviolet band LEDs, and the rest of the light converges to the sample, causing the sample to emit corresponding fluorescence, which is filtered and selected to enter the second photodiode in a specific band to complete the collection of the fluorescence signal.

[0024] In a second aspect, the present invention provides an application of the qualitative and quantitative analysis method of colored dissolved organic matter in water based on the absorption and fluorescence spectral characteristics of substances in water quality monitoring.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] The qualitative and quantitative analysis method for colored dissolved organic matter (CDOM) in water based on the absorption and fluorescence spectral characteristics of substances can more accurately distinguish different types of CDOM by selecting appropriate excitation and emission bands according to the properties of CDOM from different sources, improving the detection accuracy. Measure the fluorescence spectra of standard substances to establish a standard spectral library, measure the fluorescence spectra of actual water samples, excite the CDOM in the water samples, and then capture specific fluorescence signals, and then compare them with the spectra in the standard spectral library to quickly identify the characteristic spectra most similar to the standard substances in the spectral data, so as to judge the main source of CDOM in the water samples and complete the qualitative analysis of the samples. This method makes the detection process more intuitive and efficient. The present invention can also obtain the specific concentrations of different types of CDOM in the water samples. The qualitative and quantitative analysis method for colored dissolved organic matter (CDOM) in water based on the absorption and fluorescence spectral characteristics of substances provided by the present invention solves the problems of easy destruction of water samples, low accuracy, slow speed, and difficult in-situ monitoring in current detection methods. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0028] Figure 1 It is a flowchart of sample quantitative measurement in the qualitative and quantitative analysis method for colored dissolved organic matter (CDOM) in water based on the absorption and fluorescence spectral characteristics of substances provided by the present invention;

[0029] Figure 2 It is the optical path system provided by the present invention.

[0030] Reference numerals: 10 - UV band LEDs; 20 - beam splitter; 30 - first lens; 40 - first photodiode; 50 - second lens; 60 - third lens; 70 - filter assembly; 71 - first filter; 72 - second filter; 80 - first window; 90 - second window; 100 - sample; 110 - second photodiode. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0031] Unless otherwise defined herein, scientific and technical terms used in conjunction with the present invention shall have the meanings commonly understood by those of ordinary skill in the art. The meanings and scopes of the terms should be clear. However, in any case of potential ambiguity, the definitions provided herein shall prevail over any dictionary or extrinsic definition. In this application, unless otherwise specified, the use of "or" means "and / or". In addition, the use of the term "including" and other forms is non-restrictive.

[0032] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without making creative efforts shall fall within the protection scope of the present invention.

[0033] The first aspect of the present invention provides a method for qualitative and quantitative analysis of colored dissolved organic matter in water based on the absorption and fluorescence spectral characteristics of substances, including the following steps:

[0034] Construct an excitation and emission spectrum with an excitation band of 230 - 290 nm and an emission band of 340 - 440 nm, select standard substances of marine origin, endogenous origin, and terrestrial origin, establish a standard spectral library, and then perform qualitative measurement and quantitative measurement on the sample;

[0035] Among them, the qualitative measurement includes: measuring the excitation and fluorescence spectra of the actual water body, comparing with the standard spectra, finding characteristic spectra, and diagnosing the source of the colored dissolved organic matter; the quantitative measurement includes: analyzing with the established standard spectral library as the independent variable and the actual water body spectrum as the dependent variable to obtain the concentrations of colored dissolved organic matter of terrestrial origin, endogenous origin, and marine origin.

[0036] Specifically, the method includes the following steps:

[0037] (a) Construct an optical path: Construct an optical path system, select the excitation band and the emission band, and construct an excitation and emission spectrum;

[0038] (b) Establish a standard spectral library: Select standard substances of marine origin, endogenous origin, and terrestrial origin, obtain the spectra of the standard substances, and after concentration normalization, establish a standard excitation and fluorescence spectral library of different organic substances;

[0039] (c) Qualitative measurement of the sample: Measure the excitation and fluorescence spectra of the actual water body, compare with the standard spectra, find characteristic spectra, and diagnose the source of the colored dissolved organic matter;

[0040] (d) Quantitative measurement of the sample: Analyze with the established standard spectral library as the independent variable and the actual water body spectrum as the dependent variable to obtain the concentrations of colored dissolved organic matter of terrestrial origin, endogenous origin, and marine origin.

[0041] The qualitative and quantitative analysis method for chromophoric dissolved organic matter (CDOM) in water based on the absorption and fluorescence spectral characteristics of substances provided by the present invention is a method for rapid qualitative and quantitative analysis of CDOM in water. According to the properties of CDOM from different sources, by selecting appropriate excitation bands and emission bands, through the selection of bands, different types of CDOM can be more accurately distinguished, improving the detection accuracy; measuring the fluorescence spectra of standard substances, establishing a standard spectral library, measuring the fluorescence spectra of actual water samples, exciting the CDOM in the water samples, and then capturing specific fluorescence signals, and then comparing with the spectra in the standard spectral library, quickly identifying the characteristic spectrum most similar to the standard substance in the spectral data, so as to judge the main source of CDOM in the water sample and complete the qualitative analysis of the sample. This method makes the detection process more intuitive and efficient. The present invention can also obtain the specific concentrations of different types of CDOM in the water sample. The qualitative and quantitative analysis method for chromophoric dissolved organic matter (CDOM) in water based on the absorption and fluorescence spectral characteristics of substances provided by the present invention solves the problems of easy destruction of water samples, low accuracy, slow speed and difficult in-situ monitoring in current detection methods.

[0042] Among them, endogenous CDOM is composed of phytoplankton degradation, aquatic organism secretions, and aquatic vegetation degradation to form endogenous CDOM.

[0043] In some preferred embodiments, in the optical path construction, the excitation band includes at least one of 230 nm, 245 nm, 260 nm, 275 nm, and 290 nm.

[0044] In some preferred embodiments, in the optical path construction, the emission band includes at least one of 340 nm, 370 nm, 400 nm, and 440 nm.

[0045] Specifically, according to the properties of CDOM from different sources, different substances will emit different fluorescence under different excitation light sources. Select the excitation bands of 230 nm, 245 nm, 260 nm, 275 nm, and 290 nm, and select the emission bands of 340 nm, 370 nm, 400 nm, and 440 nm to construct the excitation and emission spectra of 20 characteristic points (i.e., 5 excitations multiplied by 4 emissions). By selecting specific excitation bands and emission bands, effective excitation can be carried out for CDOM from different sources, enabling different types of CDOM to generate specific fluorescence signals, and then these specific fluorescence signals under specific excitations can be captured. Through the selection of these specific bands, different types of CDOM can be more accurately distinguished, improving the detection accuracy.

[0046] In some preferred embodiments, humic acid, tryptophan, and fulvic acid are used as standard substances for marine-derived humic substances, endogenous protein-like substances, and terrestrial-derived humic substances, respectively.

[0047] Specifically, in the present invention, humic acid, tryptophan, and fulvic acid are used as standard substances for marine-derived humic-like substances, endogenous protein-like substances, and terrestrial-derived humic-like substances. After obtaining the spectra of these standard substances and normalizing the concentrations, a standard excitation and fluorescence spectral library for different organic substances is established.

[0048] In some preferred embodiments, in the qualitative measurement of the sample, the source of chromophoric dissolved organic matter is judged by calculating the similarity index SI between the actual water body spectrum and the standard spectrum.

[0049] In some preferred embodiments, the calculation formula of the similarity index SI is as follows:

[0050]

[0051] Wherein, A1 represents the actual water body spectrum, and A2 represents the standard spectrum.

[0052] In some preferred embodiments, SI is greater than or equal to 0 and less than or equal to 1. The similarity between the actual water body spectrum and the standard spectrum is proportional to the value of SI.

[0053] Specifically, in the present invention, the steps for qualitative measurement of the sample are as follows: Measure the excitation and fluorescence spectra of the actual water body, compare with the standard spectrum, find the most similar characteristic spectrum, and quickly diagnose the source of CDOM. Calculate the similarity index SI between the spectra by the vector cosine method. The closer SI is to 1, the higher the spectral similarity; the closer SI is to 0, the lower the spectral similarity. The standard organic substance with the highest similarity to the actual water body spectrum is the main component of CDOM in this water body. By constructing a standard spectral library and using the vector cosine method to calculate the spectral similarity index (SI), the present invention can find the characteristic spectrum most similar to the actual sample in a short time. This method simplifies the detection process and shortens the detection time.

[0054] In some preferred embodiments, in the quantitative measurement of the sample, multiple linear regression analysis is performed on the actual water body spectrum, and the formula is as follows:

[0055]

[0056] Wherein, M is the spectral data of the actual water body, f i is the standard fluorescence spectral library of a certain standard organic substance, a i is the concentration of a certain standard organic substance, k mn is the normalized fluorescence intensity of a certain standard organic substance at the excitation wavelength n and the emission wavelength m, and x represents the minimum iterative error.

[0057] Specifically, in the present invention, taking the established standard spectral library as the independent variable and the actual water body spectrum as the dependent variable, multiple linear regression analysis is performed to obtain the concentrations of terrigenous, endogenous, and marine-source CDOM. As Figure 1 shown in the flowchart of

[0058] Furthermore, preferably, the qualitative and quantitative analysis method for chromophoric dissolved organic matter in water based on the absorption and fluorescence spectral characteristics of substances comprises the following steps:

[0059] (1) Construct an optical path: According to the properties of CDOM from different sources, select excitation bands of 230, 245, 260, 275, and 290 nm, and emission bands of 340, 370, 400, and 440 nm to construct excitation and emission spectra of 20 characteristic points, and construct the optical path system as follows Figure 2 .

[0060] (2) Establish a standard spectral library: Use humic acid, tryptophan, and fulvic acid as standard substances for marine-source humic-like substances, endogenous protein-like substances, and terrigenous humic-like substances, obtain the spectra of these standard substances, and establish standard excitation and fluorescence spectral libraries for different organic substances after concentration normalization.

[0061] (3) Qualitative measurement of samples: Measure the excitation and fluorescence spectra of the actual water body, compare with the standard spectra, find the most similar characteristic spectra, and quickly diagnose the source of CDOM.

[0062] According to the requirements of step (3), the present invention calculates the similarity index SI between spectra by the vector cosine method, and the calculation formula is as follows:

[0063]

[0064] A1 and A2 respectively represent the actual water body spectrum and the standard spectrum. The closer SI is to 1, the higher the spectral similarity; the closer SI is to 0, the lower the spectral similarity. The standard organic substance with the highest similarity to the actual water body spectrum is the main component of CDOM in this water body.

[0065] (4) Quantitative measurement of samples: Taking the established standard spectral library as the independent variable and the actual water body spectrum as the dependent variable, perform multiple linear regression analysis to obtain the concentrations of terrigenous, endogenous, and marine-source CDOM.

[0066] According to the requirements of step (4), perform multiple linear regression analysis on the actual water body spectrum, and the formula is as follows:

[0067]

[0068]

[0069] where M is the spectral data of the actual water body, and f i is the standard fluorescence spectrum library of a certain standard organic substance, and a i is the concentration of a certain standard organic substance, and k mn is the normalized fluorescence intensity of a certain standard organic substance at the excitation wavelength n and the emission wavelength m, and x represents the minimum iterative error.

[0070] In some preferred embodiments, the process of constructing the optical path includes: the ultraviolet-band LEDs 10 emit excitation light, and after passing through the beam splitter 20, part of the light hits the first photodiode 40, which is used to feedback the light intensity of the ultraviolet-band LEDs 10, and the rest of the light converges on the sample 100, causing the sample 100 to emit corresponding fluorescence. After filtering, a specific band is selected and injected into the second photodiode 110 to complete the acquisition of the fluorescence signal.

[0071] In an alternative embodiment, as Figure 2 shown, the optical path system in the present invention includes ultraviolet-band LEDs 10, a beam splitter 20, a first lens 30, a first photodiode 40, a second lens 50, a third lens 60, a filter assembly 70, and a second photodiode 110; the ultraviolet-band LEDs 10 emit excitation light with a specific wavelength. After passing through the beam splitter 20, part of the light passes through the first lens 30 and hits the first photodiode 40, which is used to feedback the light intensity of the LEDs to control the consistency of the excitation light intensity for each measurement; part of the light passes through the second lens 50 and converges on the sample 100, causing the sample 100 to emit corresponding fluorescence. The fluorescence is focused by the third lens 60 and passes through the filter assembly 70 to select a specific band and is injected into the second photodiode 110 to complete the acquisition of the fluorescence signal.

[0072] Optionally, the optical path system in the present invention further includes a first window plate 80 and a second window plate 90. The first window plate 80 is disposed between the second lens 50 and the sample 100. The second window plate 90 is disposed between the sample 100 and the third lens 60.

[0073] The present invention uses an LED lamp as the light source, which has a lower cost and is easier to maintain compared with the traditional xenon lamp, and can greatly reduce the overall cost of the equipment.

[0074] Preferably, the thickness of the beam splitter 20 is 3 mm, and its length and width dimensions are 25 mm * 36 mm.

[0075] Preferably, the parameters of the first lens 30 are: f = 25 mm, D = 25 mm, T = 5.96 mm.

[0076] Preferably, the parameters of the second lens 50 are: f = 100 mm, D = 25 mm, T = 53.78 mm.

[0077] Preferably, the third lens 60 is a biconvex focusing lens with parameters f = 1.6 mm, D = 16 mm, T = 6.51 mm.

[0078] Preferably, the filter assembly 70 is disposed between the third lens 60 and the second photodiode 110. The filter assembly 70 includes a first filter 71 and a second filter 72. The first filter 71 is disposed close to the third lens 60, and the second filter 72 is disposed close to the second photodiode 110. The band-pass of the first filter is 665 - 705 nm and the thickness is 3 mm; the band-pass of the second filter is 665 - 705 nm and the thickness is 3 mm.

[0079] Preferably, the size of the first window pane 80 is 26 mm * 14 mm (length * width), and the size of the second window pane 90 is 26 mm * 14 mm (length * width).

[0080] Preferably, the distance between the ultraviolet band LEDs 10 and the beam splitter 20 is 55.6 mm, the distance between the beam splitter 20 and the first lens 30 is 30.2 mm, the distance between the first lens 30 and the first photodiode is 25.8 mm, the distance between the second lens 50 and the beam splitter 20 is 15 mm, the distance between the second lens 50 and the first window pane 80 is 9.78 mm, the distance between the second window pane 90 and the third lens 60 is 5.155 mm, the distance between the third lens 60 and the first filter 71 is 18.325 mm. There is a diaphragm between the second filter and the second photodiode. The height of the diaphragm is 3 mm and the aperture is 4 mm.

[0081] In the lens parameters of the present invention, f represents the focal length of the lens, D represents the diameter of the lens, and T represents the central thickness of the lens.

[0082] The advantages of the qualitative and quantitative analysis method for water - body colored dissolved organic matter based on the absorption and fluorescence spectral characteristics of substances provided by the present invention are as follows:

[0083] (1) Rapid diagnosis of the source of water - body CDOM through the presence of humic - like substances and protein - like substances.

[0084] (2) Establishing a standard spectrum and using multiple linear regression to explain the composition content of water - body CDOM;

[0085] (3) Compared with methods such as gas phase and liquid phase, it does not require a cumbersome pretreatment process, nor any chemical reagents, does not damage the water body, saves costs, and is environmentally friendly.

[0086] (4) Compared with the complete three-dimensional fluorescence spectrum that relies on a xenon lamp, only characteristic spectral points are selected, and LED lamps corresponding to the selected wavelength bands can be used, which reduces the measurement time and makes it easier to implement on portable and in-situ devices. At the same time, a reference optical path system is provided.

[0087] The second aspect of the present invention provides an application of the qualitative and quantitative analysis method of colored dissolved organic matter in water based on the absorption and fluorescence spectral characteristics of substances in water quality monitoring.

[0088] Example 1

[0089] Step 1. Measure standard solutions of humic acid, tryptophan, and fulvic acid at a certain concentration through the constructed optical path to obtain excitation and fluorescence spectra, which are used to indicate marine-derived humic-like substances, endogenous protein-like substances, and terrestrial-derived humic-like substances.

[0090] Step 2. Divide the excitation and fluorescence spectra obtained in Step 1 by the concentrations of the humic acid, tryptophan, and fulvic acid standard solutions to obtain the normalized spectra of the standard solutions, that is, the standard excitation and fluorescence spectra;

[0091] Step 3. Collect unknown water samples, and the spectral collection method is the same as that in Steps 1 and 2;

[0092] Step 4. First, the present invention calculates the similarity index SI between spectra through the vector cosine method for a quick qualitative judgment of the main CDOM components in the water sample.

[0093] Compare the spectra obtained in Step 3 with the standard spectra obtained in Step 2 in sequence to calculate the similarity index SI. The calculation formula is as follows:

[0094]

[0095] A1 and A2 represent the actual water body spectrum and the standard spectrum respectively. The closer SI is to 1, the higher the spectral similarity; the closer SI is to 0, the lower the spectral similarity. The standard organic substance with the highest similarity to the actual water body spectrum is the main component of CDOM in the water body.

[0096] Step 5. Based on the least squares multiple linear regression analysis idea, the present invention analyzes the actual water body spectrum and quantitatively analyzes the CDOM in the actual water body.

[0097]

[0098] Where M is the spectral data of the actual water body obtained in Step 2, f i is the standard fluorescence spectrum library of a certain standard organic substance obtained in Step 1, a i is the concentration of a certain standard organic substance, k mnis the normalized fluorescence intensity of a certain standard organic substance at the excitation wavelength n and the emission wavelength m, and x represents the minimum iterative error.

[0099] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A qualitative and quantitative analysis method for chromophoric dissolved organic matter in water based on the absorption and fluorescence spectral characteristics of substances, characterized in that, It includes the following steps: Construct excitation and emission spectra with an excitation band of 230 - 290 nm and an emission band of 340 - 440 nm, select standard substances of marine origin, endogenous origin, and terrestrial origin, establish a standard spectral library, and then conduct qualitative and quantitative measurements on the sample; Among them, the qualitative measurement includes: measuring the excitation and fluorescence spectra of the actual water body, comparing with the standard spectra, finding characteristic spectra, and diagnosing the source of chromophoric dissolved organic matter; the quantitative measurement includes: analyzing with the established standard spectral library as the independent variable and the actual water body spectrum as the dependent variable to obtain the concentrations of chromophoric dissolved organic matter of terrestrial origin, endogenous origin, and marine origin.

2. The qualitative and quantitative analysis method for chromophoric dissolved organic matter in water based on the absorption and fluorescence spectral characteristics of substances according to claim 1, characterized in that, In the construction of the optical path, the excitation band includes at least one of 230 nm, 245 nm, 260 nm, 275 nm, and 290 nm.

3. The qualitative and quantitative analysis method for colored dissolved organic matter in water based on the absorption and fluorescence spectral characteristics of substances according to claim 1, wherein In the construction of the optical path, the emission band includes at least one of 340 nm, 370 nm, 400 nm, and 440 nm.

4. The qualitative and quantitative analysis method for chromophoric dissolved organic matter in water based on the absorption and fluorescence spectral characteristics of substances according to claim 1, characterized in that In the qualitative measurement of the sample, the source of chromophoric dissolved organic matter is judged by calculating the similarity index SI between the actual water body spectrum and the standard spectrum.

5. The qualitative and quantitative analysis method for chromophoric dissolved organic matter in water based on the absorption and fluorescence spectral characteristics of substances according to claim 4, characterized in that, The calculation formula of the similarity index SI is as follows: Among them, A1 represents the actual water body spectrum, and A2 represents the standard spectrum.

6. The qualitative and quantitative analysis method for chromophoric dissolved organic matter in water based on the absorption and fluorescence spectral characteristics of substances according to claim 5, characterized in that SI is greater than or equal to 0 and less than or equal to 1, and the similarity between the actual water body spectrum and the standard spectrum is proportional to the value of SI.

7. The qualitative and quantitative analysis method for chromophoric dissolved organic matter in water based on the absorption and fluorescence spectral characteristics of substances according to claim 1, characterized in that In the quantitative measurement of the sample, multiple linear regression analysis is performed on the actual water body spectrum, and the formula is as follows: Among them, M is the spectral data of the actual water body, and f i is the standard fluorescence spectrum library of a certain standard organic substance, and a i is the concentration of a certain standard organic substance, x represents the minimum iteration error, and k mn is the normalized fluorescence intensity of a certain standard organic substance at the excitation wavelength n and the emission wavelength m.

8. The qualitative and quantitative analysis method for chromophoric dissolved organic matter in water based on the absorption and fluorescence spectral characteristics of substances according to claim 1, wherein, Using humic acid, tryptophan, and fulvic acid as standard substances for marine humic - like substances, endogenous protein - like substances, and terrestrial humic - like substances respectively.

9. The qualitative and quantitative analysis method for chromophoric dissolved organic matter in water based on the absorption and fluorescence spectral characteristics of substances according to claim 1, characterized in that The process of constructing the optical path includes: The ultraviolet - band LEDs emit excitation light. After passing through the beam splitter, part of the light hits the first photodiode for feedback on the light intensity in the ultraviolet band, and the remaining light converges on the sample, causing the sample to emit corresponding fluorescence. After filtering, specific bands are selected and incident on the second photodiode to complete the acquisition of the fluorescence signal.

10. The application of the qualitative and quantitative analysis method for chromophoric dissolved organic matter in water based on the absorption and fluorescence spectral characteristics of substances according to any one of claims 1 - 9 in water quality monitoring.

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