CN115901675A - Method for detecting ammonia nitrogen content in water body - Google Patents
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Abstract
The invention discloses a method for detecting the content of ammonia nitrogen in a water body, which relates to the technical field of ammonia nitrogen detection and comprises the following steps: (1) sample collection and processing; (2) collecting a spectrum; (3) Measuring the ammonia nitrogen content of each correction set by a chemical method; 4) Fusing and preprocessing ultraviolet visible-near infrared spectrum; (5) Constructing a detection model of the ammonia nitrogen content of the water body based on ultraviolet visible-near infrared data fusion; (6) And predicting the ammonia nitrogen content of the unknown water sample by using the constructed model. The invention has the beneficial effects that: compared with the traditional chemical method, the detection process is objective and rapid, no reagent is consumed, the sample treatment required by detection is less, and the detection process is rapid and environment-friendly; compared with the single use of ultraviolet visible spectroscopy or near infrared spectroscopy, the method has higher accuracy.
Description
Technical Field
The invention relates to the technical field of ammonia nitrogen detection, in particular to a method for detecting the content of ammonia nitrogen in a water body.
Background
The ammonia nitrogen content in the water body is ammonium ion (NH) 4 + ) And nonionic ammonia (NH) 3 ) The general term of (1) is a key index for measuring the eutrophication degree of the water body because the water body eutrophication has obvious positive correlation.
The traditional detection method for the content of ammonia nitrogen in the water body is a wet chemical method (salicylic acid spectrophotometry, a nano reagent spectrophotometry and the like), and the detection methods have the advantages of low detection efficiency, long detection time, reagent consumption, environmental pollution and difficulty in rapid evaluation and continuous real-time monitoring of the ammonia nitrogen in the water body. Therefore, a new rapid and environment-friendly technology needs to be developed to realize more rapid, accurate, objective and real-time monitoring of the ammonia nitrogen content in the water body.
Some rapid detection methods, ultraviolet-visible spectrum or near infrared spectroscopy can realize rapid detection of the ammonia nitrogen content in the water body, such as Zhang Mengwei, wang Lin. The application of an ultraviolet visible spectrophotometer in rapid determination of the mass concentration of the ammonia nitrogen in sewage [ J ]. Liaoning chemical, 2021 (050-009). The content of the ammonia nitrogen in the water body in the document is higher, and the minimum content is also 10mg/L; huang et al (https:// doi. Org/10.1080/00032719.2016.1238923) utilize near infrared to detect the ammonia nitrogen content in river water, and the ammonia nitrogen concentration of the adopted water sample is 0.57-45.04 mg/L. However, because the limit of the national standard of surface water to the content of ammonia nitrogen in five levels of surface water is between 0.15 and 2.0mg/L, these reports can only detect water samples with high ammonia nitrogen concentration, and there are few examples in which accurate detection is successfully realized at low concentration, and the requirement of detecting water bodies of all levels cannot be met. However, since the ammonia nitrogen content in water is usually in the ppm level, the accuracy of the two methods, especially the detection accuracy in low concentration water sample, needs to be further improved.
Disclosure of Invention
The invention aims to solve the technical problem of how to further improve the accuracy of a method for detecting ammonia nitrogen in a water body, and provides a method for detecting the content of ammonia nitrogen in the water body.
The invention solves the technical problems through the following technical means:
a method for detecting the content of ammonia nitrogen in a water body comprises the following steps:
(1) Sample collection and processing: collecting the organic polluted water, and removing impurities and suspended matters to be used as a correction set;
(2) Spectrum collection: collecting the near infrared spectrum of each correction set in a diffuse transmission mode, wherein the collection range of the spectrum is not less than 850nm to 1726nm; collecting the ultraviolet-visible spectrum of each correction set, wherein the collection range of the spectrum is not less than 230nm to 800nm;
(3) Determining the ammonia nitrogen content of each correction set by a chemical method;
(4) Fusing and preprocessing ultraviolet visible-near infrared spectrum: respectively intercepting fragments of which the ultraviolet visible spectrum range is 418-800nm of each water sample, intercepting fragments of which the near infrared spectrum range is 850-851.7nm and 1024.7-1286nm of each water sample, splicing the fragments end to end in sequence from low to high in wavelength, then preprocessing by using vector normalization, and taking the processed spectrum as the ultraviolet visible-near infrared fused spectrum of the water sample;
(5) Constructing a detection model of the ammonia nitrogen content of the water body based on ultraviolet visible-near infrared data fusion: processing the ultraviolet visible-near infrared fusion spectrum of the correction set and the ammonia nitrogen content determined by a chemical method by using a partial least square method, and constructing a relation model between the ultraviolet visible-near infrared fusion spectrum and the ammonia nitrogen content;
(6) And predicting the ammonia nitrogen content of the unknown water sample by using the constructed model.
Has the advantages that: compared with the traditional chemical method, the detection process is objective and rapid, no reagent is consumed, the sample treatment required by detection is less, and the detection process is rapid and environment-friendly; compared with the single use of ultraviolet visible spectroscopy or near infrared spectroscopy, the method has higher accuracy.
The parameters of the band selection and the corresponding modeling in the step (4) are screened and optimized, and if the selected spectral range and the modeling parameters are not in the range recorded by the invention, the accuracy of modeling and prediction in the invention is not higher than the accuracy of detecting the content of ammonia nitrogen in the water body by using an ultraviolet-visible spectrum technology method or a near infrared technology alone.
The method can be used for detecting ammonia nitrogen with lower concentration.
Preferably, not less than 30 parts of the organic polluted water body is collected.
Preferably, the water body with different ammonia nitrogen contents under different pollution conditions is collected in the step (1).
Has the beneficial effects that: the water sample difference is large, and the modeling precision is better.
Preferably, the collected water is filtered by a filter membrane to remove impurities and suspended substances.
Preferably, the pore size of the filter membrane is less than or equal to 0.45 μm.
Preferably, the ammonia nitrogen content of each calibration set is determined by a wet chemical method.
Preferably, the ammonia nitrogen content of each calibration set is determined by adopting a nano-reagent spectrophotometry.
Preferably, the said naesli reagent spectrophotometry comprises the following steps:
a. performing flocculation precipitation and pre-distillation on the water sample with concentrated correction;
b. adopting an ammonia nitrogen standard solution to draw a calibration curve: discharging to ammonia nitrogen standard working solution, adding sodium tartrate solution, shaking, adding Nassner reagent, standing for 10min, and measuring absorbance at wavelength of 420nm with water as reference;
c. taking a water sample, and determining the absorbance by adopting the step in the step b;
calculating the ammonia nitrogen concentration of the sample according to the following formula:
where ρ is N The mass concentration (mg/L) of ammonia nitrogen in a water sample; a. The s Absorbance of a water sample, A b Absorbance of blank test, a intercept of calibration curve, b slope of calibration curve, V volume of sample (mL).
The na's reagent is formulated by one of the following two methods:
the method comprises the following steps: mercuric dioxide-potassium iodide-potassium hydroxide (HgCl) 2 -KI-KOH) solution:
5g of potassium iodide are weighed out, dissolved in 10mL of water and 2.5g of HgCl are added with stirring 2 Adding the powder for multiple times until the solution is dark yellow or has light red precipitate, stirring and mixing completely, and adding saturated mercuric dioxide solution dropwise until a small amount of vermilion precipitate appears and no longer dissolves; adding potassium hydroxide solution (obtained by dissolving 15g of potassium hydroxide in 50mL of water and cooling) under stirring, diluting to 100mL, standing for over 24 hr, and decanting the supernatant to obtain HgCl solution 2 -KI-KOH solution.
The second method comprises the following steps: mercuric iodide-potassium iodide-sodium hydroxide (HgI) 2 -KI-NaOH) solution: weighing 7g of potassium iodide and 10g of mercuric iodide, dissolving in water, slowly adding into 50mL of sodium hydroxide solution (obtained by dissolving 16g of sodium hydroxide in 50mL of water and cooling) under stirring, and diluting with water to 100mL to obtain HgI 2 -KI-NaOH solution.
Wherein the flocculation precipitation comprises the following steps: to 100mL of the sample, 1mL of a zinc sulfate solution (ρ =100 g/L) and 0.1 to 0.2mL of a sodium hydroxide solution (ρ =250 g/L) were added, and the pH was adjusted to about 10.5, and the mixture was mixed, and the mixture was allowed to stand to precipitate, and then the supernatant was taken.
The pre-distillation comprises the following steps: 50ml of boric acid solution (p =20 g/L) was transferred into a receiving flask, ensuring the outlet of the condenser below the page of the boric acid solution, 250ml of sample was taken, transferred into a flask, several drops of bromothymol blue indicator (p =0.5 g/L) were added, after which the pH was adjusted to between 6.0 and 7.4 with sodium hydroxide solution (c (NaOH) =1 mol/L) or hydrochloric acid solution (c (HCl) =1 mol/L), 0.25g of light magnesium oxide and several glass beads were added, connecting the nitrogen ball and the condenser. Heating and distilling to ensure that the distilling rate is about 10mL/min, stopping distilling when the distillate reaches 200mL, and adding water to reach the constant volume of 250mL.
The calibration curve drawing method comprises the following steps: respectively adding 0, 0.5, 1, 2, 4, 6, 8 and 10mL of ammonia nitrogen standard working solution into 850 mL colorimetric tubes, wherein the corresponding ammonia nitrogen content is 0, 5, 10, 20, 40, 60, 80 and 100 mu g, adding water to a marked line, adding 1.0mL of sodium tartrate solution (rho =500 g/L) for shaking up, then adding 1.5mL or 1.0mL of Nashin reagent for shaking up, standing for 10 minutes, and measuring the absorbance at the wavelength of 420nm by using a 20mm cuvette and taking water as a reference. And (5) taking the absorbance after blank correction as a vertical coordinate and taking the corresponding ammonia nitrogen content (mu g) as a horizontal coordinate to draw a calibration curve.
In the step c, directly taking 50mL of clean water sample, and measuring the absorbance according to the same steps as the calibration curve; for a water sample with suspended matters or chromaticity interference, taking 50mL of the water sample subjected to flocculation precipitation pretreatment in the step a, and measuring the absorbance according to the same steps as the calibration curve; blank test: the water sample was replaced with water, and the pretreatment and measurement were carried out in the same manner as the sample.
Preferably, the number of latent variables of the partial least squares regression model constructed in the step (5) is 7.
Preferably, the steps of sample pretreatment, spectrum collection, spectrum fusion and pretreatment are sequentially performed on the water sample to be detected in the step (6) in the same manner as the correction water collection sample in the steps (1) to (4), and then the regression model constructed in the step (5) is used for predicting the treated ultraviolet visible-near infrared fusion spectrum to obtain the predicted value of the ammonia nitrogen content of the water sample to be detected.
The invention has the advantages that: compared with the traditional chemical method, the detection process is objective and quick, no reagent is consumed, the sample treatment required by the detection is less, and the detection process is quick and environment-friendly; compared with the single use of ultraviolet visible spectroscopy or near infrared spectroscopy, the method has higher accuracy.
The parameters of the band selection and the corresponding modeling in the step (4) are optimized, and if the selected spectral range and the modeling parameters are not in the range recorded by the method, the accuracy of modeling and prediction in the method is not higher than the accuracy of detecting the ammonia nitrogen content of the water body by using an ultraviolet-visible spectrum technology method or a near infrared technology alone.
Drawings
FIG. 1 is a flow chart of a method for detecting ammonia nitrogen content in a water body according to an embodiment of the invention;
FIG. 2 is a scatter diagram of a leave-one-cross validation result of a water ammonia nitrogen content detection model in the embodiment of the invention;
FIG. 3 is a prediction result scatter diagram of a water ammonia nitrogen content detection model in the embodiment of the invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, and it is obvious that the described embodiments are some embodiments of the present invention, but not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The test materials and reagents used in the following examples, etc., are commercially available unless otherwise specified.
The specific techniques or conditions not specified in the examples can be performed according to the techniques or conditions described in the literature in the field or according to the product specification.
As shown in figure 1, the method for detecting the content of ammonia nitrogen in water based on the fusion of ultraviolet visible and near infrared spectrum data specifically comprises the following steps:
s1: sample collection and processing:
50 parts of water samples with different water qualities and 20 parts of water samples with different water qualities are collected in each water source area, and the total amount of the water samples is 70 parts, and the water samples are respectively used as a correction set (recorded as a water ammonia nitrogen correction set) for calibrating the method and a verification set (recorded as a water ammonia nitrogen verification set) for verifying the result of the method. Each of the above samples was subjected to suction filtration (0.45 μm membrane filtration) with a circulating water vacuum pump to remove impurities and suspended substances.
S2: spectrum collection:
the near infrared spectrum of each water sample is collected in a diffuse transmission mode on a German Brookfield multi-point amplification (MPA) type Fourier transform near infrared spectrometer, the sample is placed in a cylindrical glass vessel during collection, the thickness of the water sample in the vessel is ensured to be 50mm, and a light source emitted by the spectrometer penetrates through the glass vessel from bottom to top to collect diffuse transmission signals. The spectrum was collected at a range of 850nm to 1726nm with a resolution of 1.13nm, once per sample.
And (3) collecting the ultraviolet-visible spectrum of each water sample on a Perkinelmer Lambda 35 type ultraviolet-visible spectrophotometer, wherein the collection range of the spectrum is 230nm to 800nm, the resolution is 1nm, and the spectrum is collected once for each sample.
S3: and (3) measuring the content of ammonia nitrogen by a wet chemical method: the method for detecting the ammonia nitrogen content of each sample by using a nano reagent spectrophotometry according to the national standard comprises the following steps:
s3a, water sample pretreatment:
when the water sample is a water sample with suspended matters or chromaticity interference, pretreatment is required before detection, and the pretreatment steps are as follows:
s3aa, flocculation and precipitation: to 100mL of the sample, 1mL of a zinc sulfate solution (ρ =100 g/L) and 0.1 to 0.2mL of a sodium hydroxide solution (ρ =250 g/L) were added, and the pH was adjusted to about 10.5, and the mixture was mixed, and the mixture was allowed to stand to precipitate, and then the supernatant was taken.
S3ab, pre-distillation: 50ml of boric acid solution (p =20 g/L) was transferred into a receiving bottle, the outlet of the condenser was ensured to be below the page of the boric acid solution, 250ml of sample was taken, transferred into a flask, a few drops of bromothymol blue indicator (p =0.5 g/L) were added, after which the pH was adjusted to between 6.0 and 7.4 with sodium hydroxide solution (c (NaOH) =1 mol/L) or hydrochloric acid solution (c (HCl) =1 mol/L), 0.25g of light magnesium oxide and several glass beads were added, and the nitrogen spheres and the condenser were connected. Heating and distilling to ensure that the distilling rate is about 10mL/min, stopping distilling when the distillate reaches 200mL, and adding water to reach the constant volume of 250mL.
S3b, calibration curve:
respectively adding 0, 0.5, 1, 2, 4, 6, 8 and 10mL of ammonia nitrogen standard working solution into 850 mL colorimetric tubes, wherein the corresponding ammonia nitrogen content is 0, 5, 10, 20, 40, 60, 80 and 100 mu g, adding water to a marked line, adding 1.0mL of sodium tartrate solution (rho =500 g/L) for shaking up, then adding 1.5mL or 1.0mL of Nashin reagent for shaking up, standing for 10 minutes, and measuring the absorbance at the wavelength of 420nm by using a 20mm cuvette and taking water as a reference. And (4) taking the absorbance after blank correction as a vertical coordinate, and taking the corresponding ammonia nitrogen content (mu g) as a horizontal coordinate to draw a calibration curve.
Naeser reagent (HgI) 2 -KI-NaOH solution) was prepared by the following method: weighing 7g of potassium iodide and 10g of mercuric iodide, dissolving in water, slowly adding into 50mL of sodium hydroxide solution (obtained by dissolving 16g of sodium hydroxide in 50mL of water and cooling) under stirring, and diluting with water to 100mL to obtain HgI 2 -KI-NaOH solution;
s3c, sample determination:
for clean water samples: 50mL of the solution was directly taken, and absorbance was measured in the same manner as in the calibration curve.
For a water sample with suspended matters or chromaticity interference, 50mL of the water sample pretreated in the step S3a is taken, and the absorbance is measured according to the same steps as the calibration curve.
Blank test: the water sample was replaced with water, and the pretreatment and measurement were carried out in the same procedure as for the sample.
And (4) calculating a result: calculating the ammonia nitrogen concentration of the sample according to the following formula:
where ρ is N The mass concentration (mg/L) of ammonia nitrogen in a water sample; a. The s Absorbance of a water sample, A b Absorbance of blank test, a intercept of calibration curve, b slope of calibration curve, V volume of sample (mL).
Descriptive statistics of ammonia nitrogen content of water samples subjected to wet chemistry measurements are shown in table 1. As can be seen from Table 1, the ammonia nitrogen content of the corrected sample set has wide distribution, and the range of the ammonia nitrogen content can cover the content range of the verification set from the national standard I to V type surface water range (the range is less than or equal to 0.15mg/L and more than 2.0 mg/L), which indicates that the sample set has good representativeness.
TABLE 1 descriptive statistics of ammonia nitrogen content of water body determined by chemical method
| Water ammonia nitrogen correction set | Water ammonia nitrogen verification set | |
| Content Range (mg/L) | 0.027-2.93 | 0.045-2.91 |
| Mean value (mg/L) | 0.486 | 0.667 |
| Standard deviation (mg/L) | 0.654 | 0.797 |
S4: fusing and preprocessing ultraviolet visible-near infrared spectrum: respectively intercepting fragments of which the ultraviolet visible spectrum interception range is 418-800nm of each water sample, intercepting fragments of which the near infrared spectrum interception range is 850-851.7nm and 1024.7-1286nm of each water sample, splicing the fragments end to end according to the sequence of wavelengths from low to high, then preprocessing by using vector normalization, and taking the processed spectrum as the ultraviolet visible-near infrared fused spectrum of the water sample.
S5: constructing a water ammonia nitrogen content detection model based on ultraviolet visible-near infrared data fusion: and processing the ultraviolet visible-near infrared fusion spectrum of the water ammonia nitrogen correction set and the corresponding wet chemical measured value of the ammonia nitrogen content by using a partial least square method, and constructing a relation model between the ultraviolet visible-near infrared fusion spectrum and the corresponding wet chemical measured value of the ammonia nitrogen content. The number of latent variables of the constructed partial least squares regression model is 7. Model correction set for ammonia nitrogen in water bodyThe cross-validation results for the samples are shown in fig. 2. As can be seen from FIG. 2, the predicted result has a high cross-validation decision coefficient (R) between the true value and the predicted value 2 cv = 0.891) and lower root mean square error (RMSECV = 0.214), indicating good modeling.
S6: and (5) predicting the unknown water sample by using the model constructed in the steps S1-S5. In the embodiment, 20 parts of water ammonia nitrogen validation set samples are used for testing, and the sample treatment and the spectrum collection are respectively as described in S1 and S2; and in the spectrum fusion step, as described in S4, an ultraviolet visible-near infrared fusion spectrum of the water ammonia nitrogen verification set is obtained, and then the ammonia nitrogen content of the verification set sample is predicted by using the ultraviolet visible-near infrared data fusion model constructed in S5.
In order to verify the accuracy of the model for predicting the ammonia nitrogen content of the water body, the ammonia nitrogen content of the verification set sample is determined by taking the Nassner reagent spectrophotometry adopted in the step S3 as a standard. The relationship between the spectrum predicted value and the chemical detection value of the ammonia nitrogen content of the verification set sample is shown in figure 3. As can be seen from FIG. 3, the prediction decision coefficient (R) between the predicted value of the spectrum of the ammonia nitrogen content and the chemical detection value of 20 water samples in the verification set is predicted by adopting an ultraviolet visible-near infrared data fusion model 2 p ) At 0.820, the predicted Root Mean Square Error (RMSEP) was 0.329. The result shows that the prediction result of the method for the ammonia nitrogen content of the water body and the chemical measurement result have higher correlation and lower error, namely the method can realize more accurate prediction for external samples.
As a comparison, respectively constructing a partial least square model by adopting the ultraviolet visible spectrum (comparison 1) and the near infrared spectrum (comparison 2) of the water ammonia nitrogen correction set collected in the step S2, and evaluating the advantages and disadvantages of the correction and prediction effects of the two models compared with the fusion model; in addition, in order to verify the superiority of the modeling parameters adopted by the invention, a partial least squares model (control 3) is constructed by using untreated ultraviolet visible-near infrared fusion spectrum (directly spliced by ultraviolet visible spectrum and near infrared spectrum without band truncation and vector normalization treatment). The comparison 1 and comparison 2 models are the optimal models screened under the combination of various spectral ranges and parameters. Wherein the water bodyThe ultraviolet visible detection model for the ammonia nitrogen content adopts the spectral ranges of 401-572nm and 629-743nm, does not adopt spectral pretreatment, and has the potential variable number of 8; the near infrared detection model for the ammonia nitrogen content of the water body adopts the spectral ranges of 850-1066.9nm and 1139.1-1222.9nm, the spectral pretreatment is first-order derivative 17-point smoothing, and the number of latent variables of the model is 9. The control 3 model uses spectra in the range of 230nm to 800nm and 850 to 1726nm with a number of modeling latent variables of 3. The four sets of model calibration and verification results are shown in table 2. As can be seen from table 2, the uv-ir fusion model used in this embodiment has better correction and prediction accuracy (higher R) than the uv-visible model and the near-ir model used only 2 cv And R 2 p Lower RMSECV and RMSEP), exhibit higher accuracy. In addition, the large prediction results of the fusion model without parameter optimization (control 3) are the worst of the models in several groups, and are even inferior to the control 1 and control 2 models, but the prediction results of the models are greatly improved after the parameter optimization of the invention, which shows that the optimization parameters adopted by the invention are necessary for accurate detection. Since the ammonia nitrogen concentration range of the sample set adopted in the embodiment covers the concentration range of all the I-V type surface water required by the national standard, the result also shows that the method can accurately predict the ammonia nitrogen at low concentration.
TABLE 2 correction and prediction results of fusion model and contrast model for ammonia nitrogen content in water
Through the technical scheme, the rapid detection method for the ammonia nitrogen content in the water body, provided by the invention, has the advantages of rapidness, environmental protection and objective and accurate detection result, and can be applied to real-time continuous monitoring of the ammonia nitrogen content in the water body. Through the modeling parameter treatment, compared with the method only using the ultraviolet-visible spectrum method or the near infrared spectrum method to detect the ammonia nitrogen content, the method has higher measurement accuracy.
The above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.
Claims (10)
1. A method for detecting the content of ammonia nitrogen in a water body is characterized by comprising the following steps: the method comprises the following steps:
(1) Sample collection and processing: collecting the organic polluted water, removing impurities and suspended matters, and taking the water as a correction set;
(2) Spectrum collection: collecting the near infrared spectrum of each correction set in a diffuse transmission mode, wherein the collection range of the spectrum is not less than 850nm to 1726nm; collecting the ultraviolet-visible spectrum of each correction set, wherein the collection range of the spectrum is not less than 230nm to 800nm;
(3) Measuring the ammonia nitrogen content of each correction set by a chemical method;
(4) Fusing and preprocessing ultraviolet visible-near infrared spectrum: respectively intercepting fragments of which the ultraviolet visible spectrum range is 418-800nm of each water sample, intercepting fragments of which the near infrared spectrum range is 850-851.7nm and 1024.7-1286nm of each water sample, splicing the fragments end to end in sequence from low to high in wavelength, then preprocessing by using vector normalization, and taking the processed spectrum as the ultraviolet visible-near infrared fused spectrum of the water sample;
(5) Constructing a detection model of the ammonia nitrogen content of the water body based on ultraviolet visible-near infrared data fusion: processing the ultraviolet visible-near infrared fusion spectrum of the correction set and the ammonia nitrogen content determined by a chemical method by using a partial least square method, and constructing a relation model between the ultraviolet visible-near infrared fusion spectrum and the ammonia nitrogen content;
(6) And predicting the ammonia nitrogen content of the unknown water sample by using the constructed model.
2. The method for detecting the content of ammonia nitrogen in the water body according to claim 1, which is characterized in that: at least 30 parts of organic polluted water is collected.
3. The method for detecting the content of ammonia nitrogen in the water body according to claim 1, which is characterized in that: and (2) collecting water bodies with different ammonia nitrogen contents under different pollution conditions in the step (1).
4. The method for detecting the content of ammonia nitrogen in the water body according to claim 1, which is characterized in that: and filtering the collected water body by using a filter membrane to remove impurities and suspended matters.
5. The method for detecting the content of ammonia nitrogen in the water body according to claim 4, which is characterized in that: the pore diameter of the filter membrane is less than or equal to 0.45 μm.
6. The method for detecting the content of ammonia nitrogen in the water body according to claim 1, which is characterized in that: and (3) measuring the ammonia nitrogen content of each correction set by adopting a wet chemical method.
7. The method for detecting the content of ammonia nitrogen in the water body according to claim 6, wherein the method comprises the following steps: and measuring the ammonia nitrogen content of each correction set by adopting a nano reagent spectrophotometry.
8. The method for detecting the content of ammonia nitrogen in a water body according to claim 7, wherein: the nano-grade reagent spectrophotometry comprises the following steps:
a. performing flocculation precipitation and pre-distillation on the water sample concentrated for correction;
b. and (3) drawing a calibration curve by adopting an ammonia nitrogen standard solution: discharging to ammonia nitrogen standard working solution, adding sodium tartrate solution, shaking, adding Nashin reagent, standing for 10min, measuring absorbance at a wavelength of 420nm with water as reference;
c. taking a water sample, and determining the absorbance by adopting the step in the step b;
calculating the ammonia nitrogen concentration of the sample according to the following formula:
where ρ is N The mass concentration (mg/L) of ammonia nitrogen in a water sample; a. The s Absorbance of a water sample, A b Absorbance of blank test, a intercept of calibration curve, b slope of calibration curve, V volume of sample (mL).
9. The method for detecting the content of ammonia nitrogen in the water body according to claim 1, which is characterized in that: the number of latent variables of the partial least squares regression model constructed in the step (5) is 7.
10. The method for detecting the content of ammonia nitrogen in the water body according to claim 1, which is characterized in that: and (3) performing sample pretreatment, spectrum collection, spectrum fusion and pretreatment on the water sample to be detected in the step (6) sequentially by adopting the same steps as the step (1) to the step (4) for correcting the collected water sample, and predicting the treated ultraviolet visible-near infrared fusion spectrum by adopting the regression model constructed in the step (5) to obtain the predicted value of the ammonia nitrogen content of the water sample to be detected.
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