Method and system for correcting DOM concentration measured based on ultraviolet absorbance method

Abstract

The invention discloses a method and system for correcting DOM concentration measured based on an ultraviolet absorbance method, and belongs to a water quality monitoring technology. Comprising the following steps: measuring absorbance data of an environmental water sample at a target wavelength of a UV-Vis wave band; solving a characteristic coefficient according to a plurality of groups of wavelengths in the UVA-Vis wave band and correspondingly measured absorbance data; constructing a characteristic function based on the characteristic coefficient obtained by solving, and substituting the target wavelength in the UVC-UVB wave band into the characteristic function to calculate suspended matter absorbance data; and subtracting suspended matter absorbance data from the measured target wavelength absorbance to obtain absorbance data of the DOM of the environmental water body under the target wavelength. Compared with the prior art, the device and the method have the advantages that the interference of suspended matters in different environmental water bodies on the ultraviolet absorption spectrum of the soluble organic matters can be automatically eliminated in real time, so that the soluble organic matters and related chemical oxygen demand (COD) indexes can be quickly and accurately detected.

Description

Technical Field

[0001] The present invention relates to the technical field of water quality monitoring, and more specifically, to a method and system for correcting the measurement of DOM concentration based on ultraviolet absorbance method. Background Art

[0002] Chemical Oxygen Demand (COD), as an important indicator for evaluating the content of Dissolved Organic Matter (DOM) in water bodies, is widely used in various water quality monitoring, including domestic sewage, industrial wastewater, surface water, and groundwater. Traditional chemical determination methods of COD include potassium dichromate method and potassium permanganate method. Although effective, they are cumbersome to operate, have a long reaction time, and rely on the consumption of a large amount of chemical reagents, making it difficult to meet the requirements of rapid real-time online monitoring. Therefore, it is particularly important to find a rapid, sensitive, and reagent-free method for determining the concentration of COD or DOM.

[0003] The wavelength range of the UVA band is 320 nm to 400 nm. The UVA band has strong penetration ability, can penetrate most transparent glasses and plastics, and can reach the dermis layer of the skin directly, damaging elastic fibers and collagen fibers and causing harm to the skin; the Vis band refers to the visible light band, with a wavelength range of 400 nm to 700 nm. The UV-Vis band refers to the ultraviolet-visible light band, which is the part of the electromagnetic spectrum located between ultraviolet and visible light, and it covers the UVA, UVB, and visible light parts.

[0004] The wavelength range of the UVC-UVB band is 100 nm to 320 nm. The wavelength range of the UVC band is 100 nm to 280 nm. The ozone layer in the Earth's atmosphere has a strong absorption effect on UVC, so UVC radiation rarely reaches the Earth's surface. UVC is mainly used for sterilization and disinfection, such as in water treatment, air purification, and medical and laboratory environments. The wavelength range of the UVB band is 275 nm to 320 nm. UVB radiation can reach the Earth's surface and is harmful to human skin to a certain extent. It should be noted that other ultraviolet bands such as UVB and UVC are not included in UVA-Vis.

[0005] Since UV-Vis analysis is based on the light absorption characteristics of substances, when a substance is irradiated with light, its molecules or ions will absorb light of specific wavelengths and transition from low energy levels to high energy levels, forming an absorption spectrum. This absorption characteristic is closely related to the composition, content, and structure of the substance. Therefore, by measuring the light absorption of the substance, in-depth analysis and inference of the properties of the substance can be carried out. The absorption spectrum refers to the curve of the absorption degree of a substance to light of different wavelengths changing with wavelength, which can reflect the absorption characteristics of the substance at different wavelengths; while the absorbance at a specific wavelength refers to the absorbance data of the substance at a certain specific wavelength, which can reflect the absorption degree of the substance at that wavelength.

[0006] In recent years, based on the significant absorption characteristics of DOM in water bodies in the UVC-UVB band (especially 250 nm - 320 nm); and research shows that there is a good linear correlation between the DOM concentration and the absorbance of UV254 or UV275. The local standard DB37 / T 4149-2020 "Determination of UV254 in Water Quality - Ultraviolet Spectrophotometry" has taken the absorbance of UV254 as an alternative method for the chemical determination of COD. This method has the advantages of high sensitivity, fast speed, and no need for chemical reagents. Existing spectral online water quality monitoring equipment includes continuous ultraviolet-visible absorption spectrometers and discrete multi-wavelength absorbance monitoring probes. However, in complex environmental water samples such as drainage systems, the concentration of suspended substances is high and variable, the cost of model training is high, and the process is complex. When determining the COD or DOM concentration based on the absorbance in the UVC-UVB band range, it still faces the interference problem of suspended substances (Suspended Substance, SS), which affects the accuracy of measurement. Although patents such as CN220603302U report pre-treating water samples by filtration before spectral measurement, the maintenance cost of the membrane module is high, the device is large in volume and high in power consumption, and it is difficult to meet the in-situ monitoring scenarios such as sewage pipe networks.

[0007] In related technologies, for example, Chinese patent CN111807548A provides a treatment method for the reuse of mung bean sprout wastewater. First, polyaluminum chloride, polyacrylamide, and lye are added to the reaction sedimentation tank to react with the mung bean sprout wastewater to remove protein pollutants in the mung bean sprout wastewater. The flocs produced by the reaction are discharged after precipitation, and the supernatant enters the air flotation tank. Then, micro-aeration is carried out in the air flotation tank through a pressurized dissolved air device, so that the suspended substances in the air flotation tank float up and are removed, and the water produced by the air flotation tank enters the membrane filtration system. The filter membrane in the membrane filtration system intercepts the suspended substances and macromolecular organic substances in the water body. Although pretreatment methods such as membrane filtration can eliminate the interference of suspended substances SS, this method is complex in operation and difficult to apply to in-situ monitoring scenarios such as sewage pipe networks.

[0008] As can be seen from the above, how to correct the interference of suspended solids (SS) on the determination of DOM concentration in real time has become an urgent problem to be solved in the field of online water quality monitoring by spectrometry. Summary of the Invention

[0009] 1. Technical Problem to be Solved Aiming at the problem in the prior art of how to improve the accuracy of water quality measurement in the presence of suspended solids interference in the drainage pipe network system, the present invention provides a method and system for correcting the measurement of DOM concentration based on the ultraviolet absorbance method, which can eliminate the interference of suspended solids on the determination of dissolved organic matter by the ultraviolet absorbance method and effectively improve the accuracy and stability of water quality measurement in the drainage pipe network system.

[0010] 2. Technical Solution The object of the present invention is achieved by the following technical solutions.

[0011] The content part of this application is used to briefly introduce the concepts, which will be described in detail in the subsequent specific implementation part. The content part of this application is not intended to identify the key features or essential features of the claimed technical solution, nor is it intended to limit the scope of the claimed technical solution.

[0012] Some embodiments of this application propose a method and system for correcting the measurement of DOM concentration based on the ultraviolet absorbance method to solve the technical problems mentioned in the above background art part.

[0013] As the first aspect of this application, some embodiments of this application provide a method for correcting the measurement of DOM concentration based on the ultraviolet absorbance method, including the following steps: measuring the absorbance data of the target wavelength in the UV-Vis band of the environmental water sample; solving the characteristic coefficients according to several groups of wavelengths in the UVA-Vis band and the corresponding measured absorbance data; constructing a characteristic function based on the obtained characteristic coefficients, substituting the target wavelength in the UVC-UVB band into the characteristic function to calculate the absorbance data of suspended solids; subtracting the calculated absorbance data of suspended solids from the measured absorbance of the target wavelength, and finally obtaining the absorbance data of DOM in the environmental water body at the target wavelength.

[0014] Furthermore, the ultraviolet-visible light band is 200 nm to 700 nm; a continuous ultraviolet-visible absorption spectrometer is used to scan the ultraviolet-visible light band to generate a continuous absorption spectral curve, and the absorbance data of the target wavelength is extracted from it.

[0015] Furthermore, the number of wavelengths selected in the UVA-Vis band ≥ 3, and the intervals between the selected wavelengths ≥ 50 nm; according to the selected wavelengths and their corresponding absorbance data to form multiple groups ( , ); Based on these data, the characteristic coefficients are solved by nonlinear fitting method, and the process is expressed as: ; Where C is the baseline offset, k is the absorbance amplitude coefficient, b is the decay rate coefficient, and e is the base of the natural logarithm; The characteristic function is constructed according to the characteristic coefficients obtained, which can be expressed as: , represents the wavelength, Indicates absorbance.

[0016] Furthermore, the nonlinear fitting adopts the nonlinear least square method, and the number of selected wavelengths is ≥3 and the interval between adjacent wavelengths is ≥50 nm.

[0017] Furthermore, the target wavelength and its corresponding absorbance data are selected in the UVC-UVB band; According to the characteristic function , calculate the wavelength Absorbance data of suspended solids , the process is expressed as: .

[0018] Furthermore, the wavelength selected in the UVC-UVB band is 254nm or 275nm.

[0019] Furthermore, the target wavelength is selected in the UVC-UVB band. , according to the absorbance data of the measured target wavelength, the DOM absorbance is calculated by differential spectroscopy, and the process is expressed as: ; in, is the absorbance data of the environmental water sample at the target wavelength. is the fitted solution data of the absorbance of the suspension, It is the absorbance data of DOM in environmental water at the target wavelength.

[0020] Furthermore, the number of wavelengths selected in the UVA-Vis band is 3, and the intervals between the three groups of wavelengths are 100 nm.

[0021] Furthermore, a continuous UV-visible spectrometer is used to measure the full-band absorption spectrum, and the absorbance data of the target wavelength is extracted therefrom.

[0022] A discrete multi-wavelength probe is used to measure the absorbance data of the target wavelength, and the probe has a built-in deep ultraviolet LED light source.

[0023] As a second aspect of the present application, some embodiments of the present application provide a system for measuring DOM concentration based on the above-mentioned method for correcting the ultraviolet absorbance method, including a determination module: determining the absorbance data of the target wavelength in the UV-Vis band of the environmental water sample; A coefficient solving module: selecting wavelengths and corresponding absorbance data in several groups of absorption spectra within the UVA-Vis band to solve the characteristic coefficients; An absorbance calculation module: constructing a characteristic function based on the characteristic coefficients obtained by solving, substituting the target wavelength within the UVC-UVB band into the characteristic function to calculate the absorbance data of suspended solids; subtracting the calculated absorbance data of suspended solids from the measured absorbance of the target wavelength, and finally obtaining the absorbance data of DOM in the environmental water body at the target wavelength.

[0024] 3. Beneficial effects Compared with the prior art, the advantages of the present invention are as follows: (1) Precise elimination of the interference of suspended solids SS: By using the negative exponential model of the SS absorbance, quantitatively deducting the absorbance contribution of SS in the UVC-UVB band, improving the detection accuracy of DOM / COD, overcoming the limitations of traditional single-wavelength calibration, reducing the pre-treatment steps of filtration compared with the traditional filtration method, and reducing the relative error of DOM detection; (2) Breaking through short-wavelength on-line monitoring: Using a deep ultraviolet probe to achieve high-precision real-time measurement of high-attenuation wavelengths such as 254 nm, reducing the measurement volatility of the on-line monitoring system and shortening the response time; (3) Flexibly adapting to complex water quality: Through the dual-mode architecture of full-spectrum scanning and discrete probe, it supports both the fine analysis of the 700 nm full band of the laboratory-grade 2600 spectrometer and the five-wavelength probe scheme; based on the multi-wavelength fitting model (≥3 interval wavelengths), reducing data dependence, taking into account both cost reduction and enhanced anti-interference ability. Description of the drawings

[0025] Figure 1 It is a schematic flow chart of the method for correcting the ultraviolet absorbance method to measure DOM concentration in an embodiment of the present invention; Figure 2 It is a graph of the absorption spectra before and after filtration of a river water sample in the UV-Vis band (200 nm - 700 nm) in an embodiment of the present invention; Figure 3 It is a schematic diagram of the absorption spectra and fitting curves of a river water sample before and after filtration in the UV-Vis band (200 nm - 700 nm) in an embodiment of the present invention. Detailed implementation manners

[0026] The present invention will be described in detail below in conjunction with the drawings of the specification and specific embodiments.

[0027] Suspended solids SS have absorption characteristics in the UV-Vis band due to absorption, occlusion, and scattering. The UV-Vis band refers to the ultraviolet-visible spectral band, which is the part between ultraviolet and visible light in the electromagnetic spectrum. By measuring and calculating the difference data of the absorption spectra before and after filtering the water sample (i.e., the differential absorption spectrum), the UV-Vis absorption spectrum of suspended solids SS in the water sample can be obtained. Through the analysis of a series of environmental water samples, it is found that the UV-Vis absorption spectrum characteristics of suspended solids SS are that the absorbance decreases monotonically with the increase of wavelength and can be fitted to a negative exponential function curve.

[0028] Since DOM has weak or no obvious absorption in the UVA-Vis band (320 nm - 700 nm) within a certain concentration range, it can be considered that the absorbance in the UVA-Vis band of environmental water bodies is mainly attributed to suspended solids SS. Based on this, the absorption spectrum of suspended solids SS in the UVC-UVB band and the absorbance at specific wavelengths can be deduced from the UVA-Vis absorption spectrum of environmental water bodies, and then the absorption spectrum of DOM in the UVC-UVB band and the absorbance at specific wavelengths can be corrected to improve the accuracy of the determination of DOM concentration and its related COD indicators.

[0029] Combined with Figures 1 to 2 , a method for correcting the measurement of DOM concentration based on ultraviolet absorbance method of the present invention includes the following steps: S1. Determination of the absorbance of environmental water samples based on full-spectrum and discrete wavelengths Determine the absorbance data of the target wavelength of the environmental water sample in the UV-Vis band, and synchronously obtain the full-band absorption spectrum according to requirements to support the interference correction of suspended solids (SS). In this embodiment, the wavelength range covered by the UV-Vis band is 200 nm - 700 nm.

[0030] In a specific embodiment, a continuous ultraviolet-visible absorption spectrometer can be used to measure the absorption spectrum of the environmental water sample in the UV-Vis band and then obtain the absorbance of the target wavelength; or a discrete multi-wavelength absorbance monitoring probe can be used to measure the absorbance of the target wavelength. Through the measurement of the full-band absorption spectrum or the discrete wavelength probe, the absorbance data of the environmental water sample at the target wavelength (including 254 nm) are obtained, and the discrete wavelength probe supports the high-precision measurement of the absorbance in the ultraviolet band (200 nm - 300 nm).

[0031] When using a continuous ultraviolet-visible spectrometer for measurement, scan the full-band absorption spectrum of 200 nm - 700 nm to generate a continuous absorbance curve (wavelength-absorbance map), so that the absorbance at any wavelength can be extracted therefrom Absorbance data. In this way, the absorbance at any target wavelength within the ultraviolet-visible light band can be obtained. Rich data can be obtained, and it can support the flexible selection of interference correction wavelengths.

[0032] Specifically, when using a discrete multi-wavelength absorbance monitoring probe for measurement, a certain target wavelength within the range of 200 nm to 700 nm in the ultraviolet-visible band can be selected for measurement, and the absorbance data at this wavelength is denoted as .

[0033] More specifically, a customized multi-wavelength probe (such as a five-wavelength probe) is adopted, with a deep ultraviolet LED light source and a high-sensitivity photoelectric sensor built in, and the absorbance at the target wavelength (such as 254 nm and 275 nm, etc.) is directly measured. The measurement of the absorbance at the 254 nm target wavelength overcomes the problems of short-wavelength light attenuation and sensor noise, realizes the support for on-line monitoring, and is especially suitable for the high-precision DOM detection at the 254 nm wavelength.

[0034] Specifically, for the determination of the absorption spectrum, a Shimadzu 2600 model UV-Vis absorption spectrometer with a tungsten lamp, a deuterium lamp or a pulsed xenon lamp as the light source can be used; for the determination of the absorbance, a five-wavelength water quality monitoring probe with an LED combined light source can be used, and the set wavelengths are 254 nm, 275 nm, 320 nm, 420 nm or 520 nm.

[0035] In a specific embodiment, before measurement, the water sample needs to be shaken and homogenized. Turbid samples should be allowed to stand and defoamed before measurement to ensure no bubble interference in the optical path.

[0036] S2. Characteristic coefficient fitting Within the UVA-Vis band, several wavelengths in the absorption spectra are selected, and the corresponding absorbance data are obtained as N groups of data at specific wavelengths. Based on this, the characteristic coefficients are solved to establish a characteristic function. In this embodiment, the value of N can be 3.

[0037] Specifically, the number of wavelengths selected within the UVA-Vis band ≥ 3, and the intervals between the selected wavelengths ≥ 50 nm to reduce the correlation between data. The selected wavelengths and their corresponding absorbance data constitute multiple groups ( , ); based on these data, the characteristic coefficients C, k, and b are solved by a non-linear fitting method.

[0038] More specifically, the absorption characteristic function of suspended solids SS is fitted by non-linear least squares method, and the process of solving the characteristic coefficients is expressed as follows: ; Wherein, C is the baseline offset, reflecting the non-wavelength-dependent absorption, k is the absorbance amplitude coefficient, which is positively correlated with the suspended solid SS concentration, b is the attenuation rate coefficient, characterizing the trend of the absorbance of the suspended solid SS changing with the wavelength, and e is the base of the natural logarithm. The relationship between the absorbance and the wavelength of the water sample in the UVA-Vis band is described by this function, and the characteristic function is constructed based on the solved characteristic coefficients: ; represents the wavelength, represents the absorbance.

[0039] In this embodiment, the wavelength range of the UVA-Vis band is 320 nm to 700 nm.

[0040] S3. Calculation of the absorbance of suspended solids Since the UVC-UVB band is more sensitive to suspended solids, this band is selected for the calculation of the absorbance of suspended solids.

[0041] Specifically, within the UVC-UVB band, the target wavelength and its corresponding absorbance data are selected; According to the characteristic coefficients C, k, and b obtained by solving in step S2, combined with the characteristic function , calculate the absorbance data of the suspended solid SS at the wavelength , and the calculation process is as follows: ; ; In a specific embodiment, the wavelength selected within the UVC-UVB band can be 254 nm or 275 nm.

[0042] S4. Solution of the absorbance of DOM Select the same target wavelength as in step S3 within the UVC-UVB band and its absorbance data , and calculate the absorbance of DOM by the differential spectroscopy method.

[0043] Specifically, at the same target wavelength selected in step S3, is the actual measured absorbance data of the environmental water sample at the specific wavelength , is the fitting solution data of the absorbance of the suspended solid in step S3. Subtract the absorbance of the suspended solid calculated in step S3 from the absorbance data measured in step S1, then the absorbance data of the DOM in the environmental water body at this target wavelength can be obtained.​​​​ The calculation method of this process is expressed as: ; Wherein, is the absorbance data of the environmental water sample measured in step S1 at the target wavelength, is the fitting solution data of the absorbance of suspended solids in step S3, and the absorbance of DOM in the environmental water body at can be solved. .

[0044] Specifically, the absorption difference spectrum before and after filtering the environmental water sample can be used to fit and obtain the absorption spectral curve of suspended solids in the environmental water sample.

[0045] In a specific embodiment, a system for correcting the measurement of DOM concentration based on the ultraviolet absorbance method of the present invention includes: Measurement module: Measure the absorbance data of the environmental water sample at the target wavelength in the ultraviolet-visible light band; Coefficient solving module: Select several groups of wavelengths and corresponding absorbance data in the absorption spectra within the UVA-Vis band to solve the characteristic coefficients; Absorbance calculation module: Establish a characteristic function based on the obtained characteristic coefficients, select the target wavelength λ within the UVC-UVB band, and substitute it into the characteristic function to calculate the absorbance of suspended solids; Subtract the calculated absorbance of suspended solids from the measured absorbance data at the target wavelength to obtain the absorbance data of DOM in the environmental water body at the target wavelength.

[0046] Through the above steps, the interference of suspended solids SS can be accurately eliminated, the absorbance contribution of SS in the UVC-UVB band can be quantitatively deducted through the negative exponential model of SS absorbance, the detection accuracy of DOM / COD can be improved, the limitations of traditional single-wavelength correction can be overcome, 90% of the pretreatment steps can be reduced compared with the traditional filtration method, and the relative error of DOM detection can be reduced; secondly, by using a deep ultraviolet probe, high-precision real-time measurement of high-attenuation wavelengths such as 254 nm can be achieved, the measurement volatility of the on-line monitoring system can be reduced, and the response time can be shortened; in addition, through the dual-mode architecture of full-spectrum scanning and discrete probe, it not only supports the fine analysis of the 700 nm full band of the laboratory-level 2600-type spectrometer, but also can select the five-wavelength probe scheme; based on the multi-wavelength fitting model (≥3 interval wavelengths), the data dependence can be reduced, and both the cost reduction and the anti-interference ability enhancement can be taken into account.

[0047] Example 1 As Figure 1 shown, when fitting according to the absorption spectrum, the process of correcting the method for measuring DOM concentration based on the ultraviolet absorbance method is as follows: First, the absorption spectrum of a certain river water sample without filtration treatment in the UV-Vis band (200 nm - 700 nm) was measured using a Shimadzu model 2600 UV-Vis absorption spectrometer and denoted as .

[0048] Secondly, the wavelengths in the UVA-Vis band range (320 nm - 700 nm) of the measured absorption spectrum and their absorbances were selected and substituted into the function to solve for the characteristic coefficients C, k, and b, thereby obtaining the absorption spectral curve of the fitting suspended solids SS in the entire UV-Vis band range.

[0049] Finally, based on the fitting absorption spectral curve of the suspended solids SS in the UV-Vis band range obtained from the above steps, the absorption spectral curve of DOM in the water sample at the UVC or UVB target wavelengths can be obtained .

[0050] Traditional DOM detection methods require filtering through a 0.45 μm filter membrane to remove SS. However, in this embodiment, a Shimadzu 2600 spectrometer was used to directly measure the full spectrum (200 nm - 700 nm) of the original water sample, and a SS absorbance model was constructed by fitting three wavelengths in the range of 320 nm - 700 nm without filtration. This greatly saves the pretreatment time compared to the traditional filtration method and avoids the loss of colloidal DOM caused by filtration. This embodiment innovatively adopts the three-wavelength spectral fitting method in the range of 320 nm - 700 nm, which can accurately analyze the absorbance of suspended solids in the unfiltered water sample without filtration pretreatment, shortening the detection time from 30 - 50 minutes of the traditional method to instantaneously complete, while avoiding the loss of colloidal DOM caused by filtration, achieving a technical breakthrough of "pre-treatment-free - high-precision" for water pollutant detection.

[0051] Example 2 In a specific embodiment, the wavelengths in the UVA-Vis band were selected as 320 nm, 420 nm, and 520 nm, and the wavelength in the UVB-UVC band was selected as 254 nm. The process of modifying the method for measuring DOM concentration based on the ultraviolet absorbance method is as follows: Measure the absorbance of a certain river water sample at specific wavelengths in the UV-Vis band (200 nm - 700 nm); select N groups of ( , ) data at specific wavelengths. In this embodiment, N = 3.

[0052] Specifically, select N groups of ( , When selecting data, the interval of the three groups of wavelengths is 100 nm, meeting the requirements of the number of groups ≥ 3 and the wavelength interval ≥ 50 nm.

[0053] In this embodiment, the data adopted are (320, 0.417), (420, 0.266), and (520, 0.206).

[0054] The solved characteristic coefficients are respectively: C = 0.0653, k = 0.7755, and b = -0.0033. Based on the solved characteristic coefficients, the characteristic function can be expressed as .

[0055] Secondly, select the target wavelength = 254 nm and its absorbance data = 0.554 in the selected UVC - UVB band (250 nm - 320 nm) and substitute them into the characteristic function with known characteristic coefficients for solution; it is obtained that = 0.444, that is, the absorbance data of suspended solids SS at the specific wavelength of 254 nm in the UVC - UVB band.

[0056] Then, select the same target wavelength = 254 nm and its absorbance data = 0.554 in the selected UVC - UVB band (250 nm - 320 nm) and substitute them into , then the absorbance of DOM in the environmental water body at 254 nm can be obtained = 0.110.

[0057] Among them, is the actually measured data of the absorbance of the environmental water sample at the specific wavelength of 254 nm, is the fitting solution data of the absorbance of suspended solids SS.

[0058] The absorbance of the river water sample at the target wavelength of 254 nm is measured by a continuous ultraviolet - visible spectrometer, expressed as * = 0.107. Comparing with the obtained , it can be found that *≈ .

[0059] Therefore, it can be considered that according to the discrete absorbance data of the UVA-Vis band (320 nm - 700 nm) of the environmental water body, the absorption spectral function curve (function formula) of suspended solids SS in the UV-Vis band (200 nm - 700 nm) and its characteristic coefficients are solved, and further the absorbance difference data between the measured data of the environmental water body and suspended solids SS in the UVC-UVB band is calculated, that is, the absorbance of DOM at specific wavelengths in the UVC-UVB band.

[0060] In this embodiment, by constructing a spectral response function model of suspended solids (SS) in the range of 200 nm - 700 nm, the accurate separation of the absorbance signals of SS and dissolved organic matter (DOM) in unfiltered water samples is realized for the first time. This technical breakthrough enables the simultaneous acquisition of the spectral characteristic coefficients of SS and the accurate absorbance of DOM at a specific UVC wavelength (such as 254 nm) in a single detection, filling the technical gap in the field of in-situ spectral analysis of water pollutants.

[0061] Example 3 In a specific embodiment, the wavelengths of the UVA-Vis band are selected as 320 nm, 420 nm, and 520 nm, and the wavelengths of the UVB-UVC band are selected as 275 nm; the method process for measuring the DOM concentration based on the ultraviolet absorbance method is corrected as follows: Measure the absorbance at specific wavelengths in the UV-Vis band (200 nm - 700 nm) of a certain river water sample; select N groups ( , ) of data at the target wavelengths. In this embodiment, N = 3.

[0062] Specifically, when selecting N groups ( , ) of data at specific wavelengths, the interval between the N groups of selected wavelengths is 100 nm, meeting the requirements of the number of groups ≥ 3 and the wavelength interval ≥ 50 nm.

[0063] In this embodiment, the data used are (320, 0.417), (420, 0.266), (520, 0.206); the solved characteristic coefficients are respectively: C = 0.0653, k = 0.7755, b = -0.0033; based on the solved characteristic coefficients, the characteristic function can be expressed as 。

[0064] Select the target wavelength = 275 nm and its absorbance data = 0.507 in the selected UVC-UVB band (250 nm - 320 nm), substitute them into the characteristic function with known characteristic coefficients, and after solution, it can be obtained that = 0.422, which is the absorbance data of suspended solids SS at a specific wavelength of 275 nm in the UVC - UVB band.

[0065] Select the same target wavelength in the selected UVC - UVB band (250 nm - 320 nm) = 275 nm and its absorbance data = 0.507, substitute it into , then the absorbance of DOM in the environmental water body at 275 nm can be obtained = 0.085.

[0066] Among them, is the actual measured data of the absorbance of the environmental water sample at a specific wavelength of 275 nm, is the fitting solution data of the absorbance of suspended solids SS.

[0067] Using a continuous ultraviolet - visible spectrometer, the absorbance of the river water sample at the target wavelength of 275 nm is measured, denoted as * = 0.082, compared with the obtained it can be found that *≈ .

[0068] Therefore, it can be considered that this solution solves the absorption spectral function curve and its characteristic coefficients of suspended solids SS in the UV - Vis band (200 nm - 700 nm) according to the discrete absorbance data of the environmental water body in the UVA - Vis band (320 nm - 700 nm), and further calculates the difference data between the measured data of the environmental water body and the absorbance of suspended solids SS in the UVC - UVB band, that is, the absorbance of DOM at a specific wavelength in the UVC - UVB band.

[0069] In this embodiment, by constructing a spectral response function model of suspended solids (SS) in the range of 200 nm - 700 nm, the accurate separation of the absorbance signals of SS and dissolved organic matter (DOM) in unfiltered water samples is realized for the first time. This technical breakthrough enables the simultaneous acquisition of the spectral characteristic coefficients of SS and the accurate absorbance of DOM at a specific UVC wavelength (such as 254 nm) in a single detection, filling the technical gap in the field of in - situ spectral analysis of water pollutants.

[0070] Example 4 In a specific embodiment, the process of modifying the method for measuring DOM concentration based on ultraviolet absorbance is as follows: The water quality monitoring probe with a specific LED combined light source of five wavelengths (254 nm, 275 nm, 350 nm, 460 nm, and 570 nm) was used to measure the water sample data of River 1, River 2, and River 3, respectively, and the absorbance data at 254 nm, 275 nm, 350 nm, 460 nm, and 570 nm were obtained respectively; (1) Measure the absorbance at specific wavelengths in the UV-Vis band (200 nm - 700 nm) of the water samples of River 1, River 2, and River 3; Select 3 groups of ( , ) data of the target wavelength.

[0071] Specifically, when selecting 3 groups of ( , ) data of the specific wavelength, the interval between the 3 selected wavelengths is 100 nm, meeting the requirements of the number of groups ≥ 3 and the wavelength interval ≥ 50 nm.

[0072] In this embodiment, the data used are for River 1: (350, 0.082), (460, 0.053), (570, 0.038); for River 2: (350, 0.075), (460, 0.044), (570, 0.033); for River 3: (350, 0.127), (460, 0.086), (570, 0.069).

[0073] The solved characteristic coefficients are for River 1: C = -0.0243, k = 0.1620, and b = -0.0016; for River 2: C = 0.0105, k = 0.1885, and b = -0.0037; for River 3: C = 0.0527, k = 0.6323, and b = -0.0064. Based on the solved characteristic coefficients, the characteristic function can be expressed as , , .

[0074] Secondly, select the target wavelength = 254 nm and its absorbance data = 0.206, = 0.160, = 0.227 in the selected UVC-UVB band (250 nm - 320 nm), and substitute them into the characteristic function with known characteristic coefficients for solution; obtain = 0.159, = 0.081, = 0.139, which is the absorbance data of suspended solids SS at the specific wavelength of 254 nm in the UVC-UVB band.

[0075] Next, select the same target wavelength within the selected UVC-UVB band (250 nm - 320 nm). = 254 nm and its absorbance data = 0.206, = 0.160, = 0.227, substitute into , then the absorbance of DOM in the water samples of River 1, River 2, and River 3 at 254 nm can be obtained = 0.047, = 0.079, = 0.088.

[0076] Among them, is the actual measured data of the absorbance of the water sample of River 1 at the specific wavelength of 254 nm, is the fitting solution data of the absorbance of suspended solids SS; is the actual measured data of the absorbance of the water sample of River 2 at the specific wavelength of 254 nm, is the fitting solution data of the absorbance of suspended solids SS; is the actual measured data of the absorbance of the water sample of River 3 at the specific wavelength of 254 nm, is the fitting solution data of the absorbance of suspended solids SS.

[0077] According to the obtained target wavelength absorbances of the water samples of River 1, River 2, and River 3 at the wavelength of 254 nm in the continuous UV-visible spectrometer, that is * = 0.043, * = 0.075, * = 0.083, compared with the obtained , it can be found that *≈ , *≈ *≈ .

[0078] (2) Measure the specific wavelength absorbances of the water samples of River 1, River 2, and River 3 in the UV-Vis band (200 nm - 700 nm); select 3 groups ( , ) of data of the target wavelength.

[0079] Specifically, when selecting 3 groups ( , ) of data of the specific wavelength, the interval between the 3 selected wavelengths is 100 nm, meeting the requirements of the number of groups ≥ 3 and the wavelength interval ≥ 50 nm.

[0080] In this embodiment, the data used are River 1: (350, 0.082), (460, 0.053), (570, 0.038); River 2: (350, 0.075), (460, 0.044), (570, 0.033); River 3: (350, 0.127), (460, 0.086), (570, 0.069).

[0081] The solved characteristic coefficients are respectively for River 1: C = -0.0243, k = 0.1620, and b = -0.0016; for River 2: C = 0.0105, k = 0.1885, and b = -0.0037; for River 3: C = 0.0527, k = 0.6323, and b = -0.0064. Based on the solved characteristic coefficients, the characteristic function can be expressed as , , .

[0082] Secondly, select the target wavelength = 275 nm and its absorbance data = 0.166, = 0.136, = 0.202 in the selected UVC - UVB band (250 nm - 320 nm), and substitute them into the characteristic function with known characteristic coefficients for solution; it is obtained that = 0.129, = 0.075, = 0.132, that is, the absorbance data of suspended solids SS at the specific wavelength of 275 nm in the UVC - UVB band.

[0083] Then, select the same target wavelength = 275 nm and its absorbance data = 0.166, = 0.136, = 0.202 in the selected UVC - UVB band (250 nm - 320 nm), and substitute them into , then the absorbance of DOM at 254 nm in the water samples of River 1, River 2, and River 3 can be obtained = 0.037, = 0.061, = 0.070.

[0084] Among them, is the actually measured data of the absorbance of the water sample of River 1 at the specific wavelength of 275 nm, is the fitting solution data of the absorbance of suspended solids SS; is the actual measured absorbance data of the water sample of River 2 at a specific wavelength of 275 nm, is the fitting solution data of the absorbance of suspended solids SS; is the actual measured absorbance data of the water sample of River 3 at a specific wavelength of 275 nm, is the fitting solution data of the absorbance of suspended solids SS.

[0085] Based on the target wavelength absorbance at 275 nm of the water samples of River 1, River 2, and River 3 obtained by a continuous UV-Vis spectrometer, that is, * = 0.034, * = 0.056, * = 0.064, compared with the obtained 、 it can be found that *≈ 、 *≈ *≈ .

[0086] Therefore, it can be considered that this scheme solves the absorption spectral function curve (function formula) and its characteristic coefficients of suspended solids SS in the UV-Vis band (200 nm - 700 nm) based on the discrete absorbance data of the UVA-Vis band (320 nm - 700 nm) of environmental water bodies, and further calculates the difference data between the measured data of environmental water bodies and the absorbance of suspended solids SS in the UVC-UVB band, that is, the absorbance of DOM at specific wavelengths in the UVC-UVB band.

[0087] Specifically, by integrating the obtained data, the data of water samples of River 1, River 2, and River 3 measured by a five-wavelength (254 nm, 275 nm, 350 nm, 460 nm, and 570 nm) water quality monitoring probe using a specific LED combination light source can be obtained, as well as the predicted absorbance data at 254 nm and 275 nm by the correction algorithm, the actual data, and the error data between the two. The specific data are shown in Table 1 and Table 2.

[0088] Table 1 Data of water samples of River 1, River 2, and River 3 measured by a five-wavelength water quality monitoring probe using a specific LED combination light source

[0089] Table 2 Predicted absorbance data at 254 nm and 275 nm by the correction algorithm, the actual data, and the error between the two

[0090] According to the data shown in Table 1 and Table 2, after analysis, the DOM prediction data obtained by the correction algorithm is relatively close to the actual data, and the errors are all within 10%. After correction, the prediction error ≤ 9.3%, which is significantly better than the error level of 21 - 35% of the uncorrected method.

[0091] The dynamic correction algorithm of the present invention greatly compresses the DOM prediction error from 21 - 35% of the traditional method to within 9.3%, which is better than the error threshold data of 15% of the international standard. Through intelligent spectral signal correction, the detection sensitivity at wavelengths of 254 nm and 275 nm is improved, and no filtration pretreatment is required. High-precision in-situ analysis of DOM in non-filtered water samples is directly achieved, effectively avoiding the problem of loss of colloidal organic matter.

[0092] The correction of the present invention is based on the method of measuring the DOM concentration by ultraviolet absorbance method. Through the correction algorithm, the absorbance curve of suspended solids (SS) in environmental water samples is fitted, and further the measured data of the environmental water body and the differential spectrum or absorbance difference data of SS in the UVC - UVB band are calculated, that is, the absorption spectrum or absorbance of DOM in the UVC - UVB band. Thus, this solution can effectively improve the accuracy and stability of water quality measurement, and can be widely applied in the field of environmental monitoring, providing strong technical support for pollution control.

[0093] The above schematically describes the present invention and its implementation manners. This description is not restrictive. Without departing from the spirit or basic characteristics of the present invention, the present invention can be implemented in other specific forms. What is shown in the drawings is only one of the implementation manners of the present invention, and the actual structure is not limited thereto. Any reference signs in the claims should not limit the claimed claims. Therefore, if those of ordinary skill in the art are inspired by it and design similar structural manners and embodiments without creative efforts without departing from the purpose of this creation, they shall fall within the protection scope of this patent. In addition, the word "comprising" does not exclude other elements or steps, and the word "a" before an element does not exclude including "a plurality of" such elements. The multiple elements stated in the product claims can also be implemented by one element through software or hardware. The words such as first and second are used to represent names and do not represent any specific order.

Claims

1. A method for correcting the measurement of DOM concentration based on ultraviolet absorbance method, characterized in that, It includes the following steps: Measure the absorbance data of the target wavelength in the UV-Vis band of the environmental water sample; Solve the characteristic coefficients according to several groups of wavelengths in the UVA-Vis band and the corresponding measured absorbance data; Construct a characteristic function based on the solved characteristic coefficients, and substitute the target wavelength in the UVC-UVB band into the characteristic function to calculate the absorbance data of suspended solids; Subtract the calculated absorbance data of suspended solids from the measured absorbance of the target wavelength to finally obtain the absorbance data of DOM in the environmental water body at the target wavelength.

2. The method for correcting the measurement of DOM concentration based on the ultraviolet absorbance method according to claim 1, wherein: The UV-Vis band is 200 nm to 700 nm; a continuous ultraviolet-visible absorption spectrometer is used to scan the ultraviolet-visible light band to generate a continuous absorption spectrum curve, and the absorbance data of the target wavelength is extracted therefrom.

3. The method for correcting the measurement of DOM concentration based on the ultraviolet absorbance method according to claim 1, wherein: The number of wavelengths selected within the UVA-Vis band is ≥ 3, and the selected wavelengths are spaced ≥ 50 nm apart from each other; according to the selected wavelengths and their corresponding measured absorbance data to form multiple groups ( , ); based on these data, the characteristic coefficients are solved by a non-linear fitting method, and the process is expressed as: ； Among them, represents the wavelength, represents the absorbance data of the measured environmental water sample at the target wavelength, C is the baseline offset, k is the absorbance amplitude coefficient, b is the attenuation rate coefficient, and e is the base of the natural logarithm; Construct a characteristic function based on the solved characteristic coefficients, expressed as: , represents the wavelength, represents the wavelength of the absorbance.

4. The method for correcting the measurement of DOM concentration based on the ultraviolet absorbance method according to claim 3, wherein: Nonlinear fitting uses the nonlinear least squares method, and the number of selected wavelengths ≥ 3 and the adjacent wavelength interval ≥ 50 nm.

5. The method for correcting the measurement of DOM concentration based on the ultraviolet absorbance method according to claim 3, wherein: Select the target wavelength and its corresponding absorbance data in the UVC-UVB band; According to the constructed characteristic function , calculate the absorbance of suspended substances at the wavelength . The process is expressed as: 。 6. The method for correcting the measurement of DOM concentration based on the ultraviolet absorbance method according to claim 5, wherein: The wavelength selected in the UVC-UVB band is 254 nm or 275 nm.

7. The method for correcting the measurement of DOM concentration based on the ultraviolet absorbance method according to claim 5, wherein: Select the target wavelength in the UVC-UVB band, and calculate the absorbance of DOM by the differential spectroscopy method according to the measured absorbance data of the target wavelength. The process is expressed as: ； wherein, is the absorbance data of the measured environmental water sample at the target wavelength, is the absorbance data of the suspended solids, is the absorbance data of DOM in the environmental water body at the target wavelength.

8. The method for correcting the measurement of DOM concentration based on the ultraviolet absorbance method according to claim 1, wherein: The number of wavelengths selected in the UVA-Vis band is 3, and the intervals between the 3 groups of wavelengths are 100 nm.

9. The method for correcting the measurement of DOM concentration based on the ultraviolet absorbance method according to claim 1, wherein: A continuous ultraviolet-visible spectrometer is used to measure the full-band absorption spectrum and extract the absorbance data of the target wavelength therefrom; or a discrete multi-wavelength probe with a deep ultraviolet LED light source built into the probe is used to measure the absorbance data of the target wavelength.

10. A system for modifying the method of measuring DOM concentration based on ultraviolet absorbance method according to any one of claims 1 to 9, characterized in that: It includes a determination module: determining the absorbance data of the target wavelength in the UV-Vis band of the environmental water sample; A coefficient solving module: selecting the wavelengths and the corresponding absorbance data in several groups of absorption spectra in the UVA-Vis band to solve the characteristic coefficients; Absorbance calculation module: Construct a characteristic function based on the obtained characteristic coefficients by solving, substitute the target wavelengths within the UVC-UVB band into the characteristic function to calculate the absorbance data of suspended matter; subtract the calculated absorbance data of suspended matter from the measured absorbance at the target wavelengths, and finally obtain the absorbance data of DOM in environmental water at the target wavelengths.

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