CN114839290B - A screening method for colored organic substances in water - Google Patents

Abstract

The invention discloses a method for screening colored organic substances in water bodies. The invention uses high-throughput screening technology to identify colored soluble substances related to water color characteristics in the research area based on correlation analysis with CDOM (440) detection values and physical and chemical properties analysis. organic matter. The present invention can screen out the soluble organic pollutants in the water body, and after determining the types of pollutants that will focus on the characteristics of the water color, the relationship between the water color characteristics of the water body and the pollutants is verified through related experiments, and the research on the relationship between the water color characteristics of the water body and the pollutants is carried out to determine the key points Pay attention to the types of pollutants that affect water color characteristics.

Description

A screening method for colored organic substances in water

technical field

The invention relates to the technical field of water body screening, in particular to a method for screening colored organic substances in water bodies.

Background technique

Chromophoric Dissolved Organic Matter (CDOM for short), suspended matter and phytoplankton are important factors affecting water color remote sensing, known as the three elements of water color. CDOM exists in all water bodies, and it is an important component of dissolved organic matter. It is composed of a series of substances such as humic acid, fulvic acid, and aromatic hydrocarbon polymers, and is mainly the degradation product of soil and aquatic plants. CDOM represents an important class of light-absorbing substances in water bodies, and its concentration and composition can significantly change the underwater light field. At present, the research on CDOM in water mainly focuses on CDOM light absorption characteristics, fluorescence characteristics, photochemical degradation and water color remote sensing of CDOM and DOC. And CDOM water color remote sensing research can be roughly divided into two directions: one is how to eliminate CDOM interference when performing water color remote sensing of phytoplankton and suspended matter, so as to improve remote sensing accuracy; the other is to study how to directly detect the temporal and spatial distribution of CDOM and DOC.

Along with water temperature, salinity and transparency, water body color is one of the oldest time-series water quality data and is an important content in traditional surface water quality surveys. In recent years, water body color has been listed as one of the basic climate variables of lakes by the World Meteorological Organization and the Global Climate Observing System Program. The color change of the water body is directly related to the change of the concentration of optical components in the water, which is an important optical feature of the water body. The temporal and spatial changes of the water quality of the water body can be monitored by means of the color of the water body, such as the change of chlorophyll concentration and turbidity of ocean water, and the change of turbidity of lake water, etc. etc., and can detect natural events and human disturbances in water bodies, such as harmful algal blooms, black water clusters, urban black and odorous water and colored sewage discharges, etc.

Therefore, in order to study the colored soluble organic matter in the water body of the watershed, the surface samples of the water body of the typical watershed reservoir are collected, the present invention adopts the high-throughput screening technology, and based on the correlation analysis with the CDOM (440) detection value and the analysis of the physical and chemical properties, the identification of the research area and the water color Characteristic associated colored soluble organic compounds.

Contents of the invention

The purpose of the present invention is to provide a screening method for colored organic substances in water bodies, which can screen soluble organic pollutants in water bodies. After determining the types of pollutants that will focus on the characteristics of water color, after verifying the relationship between water color characteristics and pollutants, carry out related experiments. Research on the relationship between water color characteristics and pollutants to determine the types of pollutants that affect water color characteristics.

In order to achieve the above object, the present invention is achieved through the following technical solutions: a method for screening colored organic substances in water, comprising the following steps:

1. Sample collection: collect water samples at the sampling point, wash the sampler and the water sample container 2 to 3 times with the collected water sample, then collect the water sample into the container, add a fixative, shake well, and stick it well Label;

2. Qualitative analysis of actual samples: For actual samples, the qualitative analysis of pollutants is completed with the help of high-throughput screening equipment (samples are collected for no less than 2 water periods). GC×GC-TOF-MS analysis is recommended, and the sampling method is Automatic sampling, injection volume is 1μL, ion scanning range: 50-500, ion source temperature: 240°C, interface temperature: 280°C, ionization energy: 70eV, chromatographic column: one-dimensional column: DB-5MS (30m×0.25 mm×0.25μm); two-dimensional column: Rxi-175Sil MS (1.2m×0.15mm×0.15μm), carrier gas flow rate: 1.5mL/min, quantitative method: internal standard method internal standard: Acstandard Z-104J; Gas chromatography temperature programming conditions: one-dimensional column temperature program: initial temperature 60°C, hold for 0.5min; increase to 200°C at a rate of 6°C/min; then increase to 235°C at a rate of 3°C/min; finally increase to 4°C Raise the rate per minute to 300°C and hold for 2min; the two-dimensional furnace temperature compensation temperature is 5°C, the modem compensation temperature is 15°C; the modulation period is 7s, and the heat blowing time is 1.4s;

3. Quantitative analysis of actual samples: For actual samples, the quantitative analysis of pollutants is completed with the help of gas chromatography mass spectrometer. It is recommended to use GC-MS analysis, equipped with 30m DB-5MS (5% diphenyl/95% dimethyl polysiloxane alkane, 30m×0.25mm×0.25μm film); the splitless injection method was adopted, the carrier gas was high-purity He, the constant flow was 1.5mL·min ^-1 , and the injection volume was 1μL; the temperatures of the ion source and transfer rod were respectively 230 °C and 250 °C;

4. Absorbance analysis of samples: For actual samples and laboratory samples, the spectrum measurement is completed with the help of a UV-Vis spectrophotometer. The recommended detection method is: the wavelength range is 240 to 750nm; the measurement uses ultrapure water as a blank reference; the absorption coefficient of CDOM Then it is obtained by the following formula:

ag'(λ)=2.303×D(λ)/r

ag(λ)=ag'(λ)-ag'(700)×λ/700

where ag′(λ) and ag(λ) represent the uncorrected CDOM absorption coefficient and the scattering-corrected absorption coefficient (m ^-1 ) at wavelength λ, respectively; D(λ) represents the absorbance measured by the instrument at wavelength λ; and r represents the optical path length (m) of the cuvette;

Due to the complex composition of CDOM, its concentration is difficult to measure directly, so the absorption coefficient of 355nm (ag(355)), the absorption coefficient of 400nm (ag(400)) or the absorption coefficient of 440nm (ag(440)) are used to represent CDOM The concentration of CDOM; the specific absorption coefficient (SUVA254) of CDOM in the 254nm band is used to characterize the light absorption ability of CDOM per unit DOC concentration, which is obtained by the following formula:

SUVA254=ag(254)/DOC

The spectral slope of CDOM is calculated using a single exponential function according to the nonlinear regression method of the following formula:

ag(λ)=ag(λ0)×exp[-Sg(λ-λ0)]

In the formula, λ0 represents the reference wavelength (nm), and Sg represents the spectral slope of the exponential function curve (μm ^-1 );

5. Data processing: High-throughput screening detects a wide variety of pollutants, so it is necessary to select the detection data. The specific selection principle is that the matching degree of the compound spectrum is > 700; the detection rate of the compound is > 50%. The correlation between pollutant concentration and absorbance was analyzed by index method; the absorbance was fitted by SPSS software for fitting calculation of related indicators.

Beneficial effects of the present invention: the present invention uses high-throughput screening technology to identify colored soluble organic matter related to water color characteristics in the research area based on correlation analysis with CDOM (440) detection value and physical and chemical property analysis. The screening method is convenient and reliable in operation, good in detection effect and strong in practicability.

Description of drawings

The present invention is described in detail below in conjunction with accompanying drawing and specific embodiment;

Fig. 1 is that the present invention focuses on pollutants and CDOM (440) correlation analysis fitting curve;

Fig. 2 is a schematic diagram of the myristic acid absorbance fitting curve of the present invention;

Fig. 3 is a schematic diagram of the DEET absorbance fitting curve of the present invention;

Fig. 4 is the schematic diagram of the fitting curve of di-tert-butylbenzoquinone absorbance of the present invention;

Fig. 5 is the octadecanoic acid absorbance fitting curve schematic diagram of the present invention;

Fig. 6 is a schematic diagram of relevant parameters of the absorbance fitting curve of the present invention;

Fig. 7 is a schematic diagram of the absorbance fitting curve of the present invention.

Detailed ways

In order to make the technical means, creative features, goals and effects achieved by the present invention easy to understand, the present invention will be further described below in conjunction with specific embodiments.

Referring to Figures 1-7, the present embodiment adopts the following technical solutions: a method for screening colored organic substances in water, comprising the following steps:

1. Sample collection: collect water samples at the sampling point, wash the sampler and the water sample container 2 to 3 times with the collected water sample, then collect the water sample into the container, add a fixative, shake well, and stick it well Label;

2. Qualitative analysis of actual samples: For actual samples, the qualitative analysis of pollutants is completed with the help of high-throughput screening equipment (samples are collected for no less than 2 water periods). GC×GC-TOF-MS analysis is recommended, and the sampling method is Automatic sampling, injection volume is 1μL, ion scanning range: 50-500, ion source temperature: 240°C, interface temperature: 280°C, ionization energy: 70eV, chromatographic column: one-dimensional column: DB-5MS (30m×0.25 mm×0.25μm); two-dimensional column: Rxi-175Sil MS (1.2m×0.15mm×0.15μm), carrier gas flow rate: 1.5mL/min, quantitative method: internal standard method internal standard: Acstandard Z-104J; Gas chromatography temperature programming conditions: one-dimensional column temperature program: initial temperature 60°C, hold for 0.5min; increase to 200°C at a rate of 6°C/min; then increase to 235°C at a rate of 3°C/min; finally increase to 4°C Raise the rate per minute to 300°C and hold for 2min; the two-dimensional furnace temperature compensation temperature is 5°C, the modem compensation temperature is 15°C; the modulation period is 7s, and the heat blowing time is 1.4s;

3. Quantitative analysis of actual samples: For actual samples, the quantitative analysis of pollutants is completed with the help of gas chromatography mass spectrometer. It is recommended to use GC-MS analysis, equipped with 30m DB-5MS (5% diphenyl/95% dimethyl polysiloxane alkane, 30m×0.25mm×0.25μm film); the splitless injection method was adopted, the carrier gas was high-purity He, the constant flow was 1.5mL·min ^-1 , and the injection volume was 1μL; the temperatures of the ion source and transfer rod were respectively 230 °C and 250 °C;

4. Absorbance analysis of samples: For actual samples and laboratory samples, the spectrum measurement is completed with the help of a UV-Vis spectrophotometer. The recommended detection method is: the wavelength range is 240 to 750nm; the measurement uses ultrapure water as a blank reference; the absorption coefficient of CDOM Then it is obtained by the following formula:

ag'(λ)=2.303×D(λ)/r

ag(λ)=ag'(λ)-ag'(700)×λ/700

where ag′(λ) and ag(λ) represent the uncorrected CDOM absorption coefficient and the scattering-corrected absorption coefficient (m ^-1 ) at wavelength λ, respectively; D(λ) represents the absorbance measured by the instrument at wavelength λ; and r represents the optical path length (m) of the cuvette;

Due to the complex composition of CDOM, its concentration is difficult to measure directly, so the absorption coefficient of 355nm (ag(355)), the absorption coefficient of 400nm (ag(400)) or the absorption coefficient of 440nm (ag(440)) are used to represent CDOM The concentration of CDOM; the specific absorption coefficient (SUVA254) of CDOM in the 254nm band is used to characterize the light absorption ability of CDOM per unit DOC concentration, which is obtained by the following formula:

SUVA254=ag(254)/DOC

The spectral slope of CDOM is calculated using a single exponential function according to the nonlinear regression method of the following formula:

ag(λ)=ag(λ0)×exp[-Sg(λ-λ0)]

In the formula, λ0 represents the reference wavelength (nm), and Sg represents the spectral slope of the exponential function curve (μm ^-1 );

5. Data processing: High-throughput screening detects a wide variety of pollutants, so it is necessary to select the detection data. The specific selection principle is that the matching degree of the compound spectrum is > 700; the detection rate of the compound is > 50%. The correlation between pollutant concentration and absorbance was analyzed by index method; the absorbance was fitted by SPSS software for fitting calculation of related indicators.

Example 1:

A method for screening colored organic substances in water bodies, comprising the following steps:

1. Sample collection

Samples for all indicators were collected in the Panjiakou and Daheiting reservoir areas, and water samples were collected in accordance with the "Water Environment Monitoring Specification" (SL219-2013). In order to ensure the representativeness of the samples and ensure the accurate location of the sampling points, a locator (GPS) was used for positioning. At the same time, it is equipped with full-time sampling personnel and special sampling facilities (vehicle refrigerator, incubator, etc.) to ensure that the water samples are in the delivery environment required by the specification. Wash the sampler and the water sample container 2 to 3 times for the collected water sample, then put the water sample into the container, and immediately add the corresponding fixative as required, shake well, and stick the label. The number of quality control samples such as on-site blank samples, on-site parallel samples, and on-site standard samples should reach 10% to 20% of the total number of water samples, and each batch of water samples should not be less than 1.

2. Qualitative analysis of actual samples

In this example, the instrument detection of high-throughput screening of compounds mainly uses GC×GC-TOF-MS analysis, the injection method is automatic injection, the injection volume is 1 μL, the ion scanning range: 50-500, and the ion source temperature: 240℃, interface temperature: 280℃, ionization energy: 70eV, chromatographic column: one-dimensional column: DB-5MS (30m×0.25mm×0.25μm); two-dimensional column: Rxi-175SilMS (1.2m×0.15mm×0.15μm ), carrier gas flow rate: 1.5mL/min, quantitative method: internal standard method, internal standard substance: Acstandard Z-104J; gas chromatography temperature programming conditions: one-dimensional column temperature program: initial temperature 60 ° C, retain 0.5 min; Rise to 200°C at a rate of ℃/min; then rise to 235°C at a rate of 3°C/min; finally rise to 300°C at a rate of 4°C/min and hold for 2 minutes. Two-dimensional furnace temperature compensation temperature: 5°C, modem compensation temperature: 15°C. The modulation period is 7s, and the heat blowing time is 1.4s.

3. Quantitative analysis of actual samples

Use GC-MS to quantitatively analyze the colored organic compounds (here six types of compounds) in actual samples, equipped with 30m DB-5MS (5% diphenyl/95% dimethyl polysiloxane, 30m×0.25mm ×0.25μm film); the splitless injection method was adopted, the carrier gas was high-purity He, the constant flow was 1.5mL·min ^-1 , and the injection volume was 1μL. The temperature of the ion source and the transfer rod are 230°C and 250°C, respectively; the derivatization standard sample heating program: the initial temperature is 90°C, the rate is raised to 230°C at a rate of 5°C/min, and then the rate is increased to 280°C at a rate of 15°C/min Keep it for 1min. Derivatization-free standard sample heating program: initial temperature 90°C, increase to 160°C at a rate of 5°C/min, then increase to 280°C at a rate of 15°C/min and hold for 1 min. Derivatization process: Take 50 μL standard solution into the 250 μL plastic liner in the sample bottle, add 50 μL silanization reagent (99:1/BSTFA-TMCS), immediately tighten the bottle cap, mix well, and then measure on the machine. The whole process should avoid contact with water and the samples and derivatization reagents should not be exposed to the air for a long time.

4. Sample absorbance analysis

For the CDOM absorption coefficient of actual samples and laboratory samples, the spectrum was measured by UV-Vis spectrophotometer. The measurement wavelength range is 240 to 750 nm (1 nm interval). Use ultrapure water as a blank reference during measurement. The absorption coefficient of CDOM is obtained by the following formula:

ag'(λ)=2.303×D(λ)/r

ag(λ)=ag'(λ)-ag'(700)×λ/700

where ag′(λ) and ag(λ) represent the uncorrected CDOM absorption coefficient and the scattering-corrected absorption coefficient (m ^-1 ) at wavelength λ, respectively; D(λ) represents the absorbance measured by the instrument at wavelength λ; and r represents the optical path length (m) of the cuvette, and a cuvette with an optical path length of 10 cm was used in the measurement of CDOM in this embodiment.

Due to the complex composition of CDOM, its concentration is difficult to measure directly, so it is usually represented by the absorption coefficient of 355nm (ag(355)), the absorption coefficient of 400nm (ag(400)) or the absorption coefficient of 440nm (ag(440)) Concentration of CDOM. This example uses ag(355) to characterize CDOM content. The ratio (E2/E3) of the absorption coefficient of CDOM at 250nm wavelength (ag(250)) to the absorption coefficient of 365nm wavelength (ag(365)) is used to characterize the molecular weight of CDOM. The specific absorption coefficient (SUVA254) of CDOM in the 254nm band is used to characterize the light absorption ability of CDOM per unit DOC concentration, which is obtained by the following formula:

SUVA254=ag(254)/DOC

The spectral slope of CDOM is calculated using a single exponential function according to the nonlinear regression method of the following formula:

ag(λ)=ag(λ0)×exp[-Sg(λ-λ0)]

In the formula, λ0 represents the reference wavelength (nm), which is 440 nm in this embodiment; Sg represents the spectral slope (μm ⁻¹ ) of the exponential function curve. In this embodiment, the corresponding Sg values (S275-295, S350-400 and S400-600) are obtained by performing nonlinear fitting calculation on the 275-295nm, 350-400nm and 400-600nm band ranges respectively.

5. Data processing

There are many types of pollutants detected by high-throughput screening, so it is necessary to select the detection data. The specific selection principle is that the matching degree of the compound spectrum is > 700; the detection rate of the compound is > 50%, that is, there are more than 4 points in a single time If the compound is detected multiple times, select the peak area with the same peak time as the reference area. The correlation between pollutant concentration and absorbance was analyzed by index method. The absorbance was fitted using SPSS software to perform fitting calculations on relevant indicators.

6. Result analysis

1) Analysis of high-throughput screening results of colored soluble organic compounds

According to the above-mentioned high-throughput screening pollutant detection method, the water samples collected in September 2017 and June 2018 were pre-treated and tested. The specific test results were analyzed according to the above-mentioned high-throughput screening data selection principles. A total of 288 and 66 compounds were selected respectively; the results of the two tests were summarized, and a total of 44 intersection compounds were selected. According to the correlation analysis between the detection results of each sampling point in different periods and CDOM (440), there are 15 compounds with a correlation index ^R2 above 0.6, namely 2-fluorobiphenyl, dibutyl atrazine, arginine Terazine, DEET, Caffeine, 2,4,7,9-Tetramethyl-5-Decyne-4,7-diol, N,N-Dibutylformamide, Dodecanal, Tetradecane acid, 2,6-di-tert-butylbenzoquinone, octadecanoic acid, 2,4,6-tribromophenol, oleic acid amide, phthalates and 1-eicosanol. The specific correlation fitting curve is shown in Figure 1.

2) Focus on the results analysis of soluble colored organic compounds

For the above 15 compounds, physical and chemical data were collected, see Table 1. The analysis found that the white or colorless compounds were 2-fluorobiphenyl, dibutyl atrazine, atrazine, caffeine, 2,4,7,9-tetramethyl-5-decyne-4, There are 9 kinds of 7-diol, N,N-dibutylformamide, oleic acid amide, phthalate and 1-eicosanol; the colored compounds include DEET, dodecanal, myristic acid, 2 , 6-di-tert-butylbenzoquinone, octadecanoic acid and 2,4,6-tribromophenol, a total of 6 kinds.

Table 1 focuses on the related properties of soluble colored organic compounds

3) Analysis of the relationship between soluble colored organic matter and water color characteristics

For the six types of compounds determined in the previous work, carry out the CDOM absorbance verification experiment in the laboratory. The specific operation steps are: add 100ppm standard solution to the graduated colorimetric tube filled with 10mL ultrapure water, and prepare 500ppb, 1ppm, 2ppm, and 5ppm respectively 10ppm of the six types of compound solution, after shaking for 5 minutes, ultrasonic for 10 minutes, using a UV-visible spectrophotometer, measure the absorbance of the solution at wavelengths of 355nm, 400nm and 440nm, and draw the absorbance curve of the solution. The experimental results show (Fig. 2 to Fig. 5), among the six types of compounds, the concentration of the four types of compounds including myristic acid, DEET, di-tert-butylbenzoquinone and octadecanoic acid have a good fit with the relevant CDOM values. Compatibility (under exponential function fitting, R ² ≥0.976). It can be inferred that the four types of compounds in the water body have the basic conditions to affect the water body remote sensing detection.

4) Analysis of the fitting verification results of the relationship between the actual sample and the water color characteristics

The water body of the Panjiakou-Daheiting Reservoir was collected in September 2020. It is planned to obtain the relationship between the six types of compounds and the water color characteristics through the concentration detection of the six types of compounds in the actual samples and the CDOM detection of the water body.

In terms of CDOM detection of actual samples: 200mL of water samples were collected and processed into CDOM samples for testing. First, the water sample is filtered at low pressure (not higher than 30kPa) by using Whatman GF/F glass fiber filter membrane with a diameter of 47mm and a pore size of 0.7μm (pre-packaged with aluminum foil and burned in a muffle furnace at 450°C for 4 hours), Use a Millipore filter membrane with a pore size of 0.22 μm to filter the filtered water sample of the above part, take 60 mL of the filtered water sample again and store it in a brown glass bottle (rinse with the filtered solution three times first), store it in the refrigerator as a CDOM sample Refrigerate at 4°C for testing. The absorbance of water samples was measured at wavelengths of 355nm, 400nm and 440nm using a UV-visible spectrophotometer.

Table 2 Absorbance of Panda Reservoir water samples at different wavelengths

Using SPSS software to perform fitting calculations on relevant indicators (results shown in Figure 6), it was found that except for leaf green, suspended solids and transparency, the fitting significance of DEET was as high as 0.829, while the selected myristic acid, octadecanoic acid The significance of alkanoic acid and tert-butylbenzoquinone is between 0.074 and 0.576. The schematic diagram of the relevant fitting results is shown in Figure 7.

7. Conclusion

Through the research on the relationship between water color characteristics and pollutants, the primary focus is on the types of pollutants that affect water color characteristics.

(1) After two high-throughput screenings in different water seasons, a key organic compound list containing 44 organic compounds was established; correlation analysis was carried out with the detection values of the corresponding sample CDOM (440), and 15 remote sensing related Organic compounds: The physical and chemical properties of 15 organic compounds related to remote sensing were analyzed, and 6 colored soluble organic compounds related to remote sensing were preliminarily determined.

(2) In the laboratory, it was verified that among the 6 kinds of colored soluble organic compounds related to remote sensing, only four compounds, DEET, myristic acid, octadecanoic acid and tert-butylbenzoquinone, could fit the curve relationship between absorbance and concentration.

(3) Through the verification of actual samples outside the laboratory, it was found that DEET was significantly higher, or it was an important soluble organic pollutant affecting the water color characteristics in the study area.

The basic principles and main features of the present invention and the advantages of the present invention have been shown and described above. Those skilled in the industry should understand that the present invention is not limited by the above-mentioned embodiments. What are described in the above-mentioned embodiments and the description only illustrate the principle of the present invention. Without departing from the spirit and scope of the present invention, the present invention will also have Variations and improvements are possible, which fall within the scope of the claimed invention. The protection scope of the present invention is defined by the appended claims and their equivalents.

Claims (1)

1. A screening method for colored organic substances in water bodies, characterized in that, comprising the following steps: (1) Sample collection: collect water samples at the sampling point, wash the sampler and the water sample container 2 to 3 times with the collected water sample, then collect the water sample into the container, add fixative and shake well, affix a good label; (2) Qualitative analysis of actual samples: For actual samples, the qualitative analysis of pollutants is completed with the help of high-throughput screening equipment, and GC×GC-TOF-MS is used for analysis. The injection method is automatic injection, and the injection volume is 1 μL. Ion scanning range: 50-500, ion source temperature: 240°C, interface temperature: 280°C, ionization energy: 70eV, chromatographic column: one-dimensional column: DB-5MS 30m×0.25mm×0.25μm; two-dimensional column: Rxi- 175Sil MS 1.2m×0.15mm×0.15μm, carrier gas flow rate: 1.5mL/min, quantitative method: internal standard method internal standard: Acstandard Z-014J; gas chromatography temperature programming conditions: one-dimensional column temperature program: initial temperature 60°C, hold for 0.5min; rise to 200°C at a rate of 6°C/min; then rise to 235°C at a rate of 3°C/min; finally rise to 300°C at a rate of 4°C/min, hold for 2min; two-dimensional Furnace temperature compensation temperature: 5°C, modem compensation temperature: 15°C; modulation cycle: 7s, heat blowing time: 1.4s; (3) Quantitative analysis of actual samples: For actual samples, the quantitative analysis of pollutants is completed with the help of gas chromatography mass spectrometer, using GC-MS analysis, equipped with 30m DB-5MS 5% diphenyl/95% dimethyl polysiloxane Alkanes, 30m×0.25mm×0.25μmfilm; the splitless injection method was adopted, the carrier gas was high-purity He, the constant flow was 1.5mL·min ^-1 , and the injection volume was 1μL; the temperatures of the ion source and transfer rod were 230℃ and 250°C; (4) Absorbance analysis of samples: For actual samples and laboratory samples, the spectrum measurement is completed with the help of a UV-visible spectrophotometer. The detection method is: the wavelength range is 240 to 750nm; ultrapure water is used as a blank reference during measurement; the absorption of CDOM The coefficients are then given by the following formula: ag'(λ)=2.303×D(λ)/r ag(λ)=ag'(λ)–ag'(700)×λ/700 where ag'(λ) and ag(λ) represent the uncorrected CDOM absorption coefficient and the scattering-corrected absorption coefficient m ^-1 at wavelength λ, respectively; Dλ represents the absorbance measured by the instrument at wavelength λ; and r represents the cuvette The optical path length m; Due to the complex composition of CDOM, its concentration is difficult to measure directly, so the absorption coefficient ag(355) at 355nm, ag(400) at 400nm or ag(440) at 440nm are used to represent the concentration of CDOM; CDOM is at 254nm The specific absorption coefficient SUVA254 of the band is used to characterize the light absorption ability of CDOM per unit DOC concentration, which is obtained by the following formula: SUVA254=ag(254)/DOC The spectral slope of CDOM is calculated using a single exponential function according to the nonlinear regression method of the following formula: ag(λ)=ag(λ0)×exp[-Sg(λ-λ0)] In the formula, λ0 represents the reference wavelength nm, and Sg represents the spectral slope of the exponential function curve μm ^-1 ; (5) Data processing: There are many types of pollutants detected by high-throughput screening, so it is necessary to select the detection data. The specific selection principle is that the matching degree of the compound spectrum is > 700; The correlation between concentration and absorbance was analyzed by exponential method; the absorbance was fitted by SPSS software for fitting and calculation of related indicators.

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