Methods, equipment, media, and products for nitrate source analysis in water bodies using coupled nitrogen, oxygen, and boron isotope tracing.

Abstract

This application discloses a method, equipment, medium, and product for nitrate source identification in water bodies coupled with nitrogen and oxygen isotope and boron isotope tracing, relating to the field of environmental monitoring technology. The method includes: collecting water samples and samples from different pollution sources at sampling points deployed within a study area according to a hydrological cycle; preprocessing the water samples and samples from different pollution sources; performing isotope determination of water treatment information using a stable isotope ratio mass spectrometer and a multi-receiver inductively coupled plasma mass spectrometer; calculating the contribution rate of different pollution sources to nitrate in water bodies based on the MixSIAR model and nitrate nitrogen and oxygen isotope data, obtaining the nitrate contribution rate of different endmembers; and using an endmember mixing model to distinguish pollution flows with similar nitrogen and oxygen isotope fingerprints based on boron isotope data, quantifying the contribution ratio of sewage and manure. This application can improve the accuracy of water pollution source identification and provide a basis for regional water environment management and pollution control.

Description

Technical Field

[0001] This application relates to the field of environmental monitoring technology, and in particular to a method, equipment, medium and product for nitrate source analysis in water bodies coupled with nitrogen and oxygen isotope and boron isotope tracing. Background Technology

[0002] For tracing the source of nitrate pollution in irrigation areas, traditional methods such as hydrochemical statistics and land use analysis are mainly qualitative, lacking sufficient quantitative precision; based on nitrate nitrogen and oxygen dual isotope analysis... , While source apportionment techniques can distinguish typical sources such as chemical nitrogen fertilizers, organic fertilizers / sewage, soil organic nitrogen, and atmospheric deposition, and can quantify contribution rates using mixed models such as SIAR and MixSIAR, limitations remain. For example, quantitative results from the MixSIAR model show that the main sources and contribution rates of nitrate in a certain river's main stream are: manure / sewage (35%-45%), chemical fertilizers (25%-35%), soil organic nitrogen mineralization (15%-25%), atmospheric deposition (3%-8%), and irrigation water from the Yellow River (5%-10%). Groundwater in the irrigation area is more significantly affected by agricultural non-point source pollution, with livestock and poultry farming and sewage contributing 44.5%-51.1%, chemical fertilizers 28.7%-30%, and soil organic nitrogen 15%-20%. Furthermore, manure accounts for a higher proportion during the dry season, while chemical fertilizers make a significant contribution during the wet season. It is worth noting that livestock and poultry manure... Typically, it ranges from +8‰ to +25‰. The range is +0‰ to +10‰; while the wastewater... The range is from +10‰ to +22‰. The concentration ranges from +5‰ to +15‰. This makes it difficult to accurately distinguish between the two using only dual-isotope mapping methods, becoming a core bottleneck in current source tracing efforts. Studies have confirmed that when using Bayesian mixture models such as SIAR to invert the contribution rates of feces and sewage, the uncertainty can reach as high as ±22% to ±38%. However, current technology cannot reliably distinguish between these two pollution streams with similar isotopic "fingerprints," leading to unclear boundaries of responsibility for controlling anthropogenic point sources (sewage) and agricultural non-point sources (livestock and poultry manure). Therefore, it is urgent to develop an integrated and innovative source tracing framework to overcome current technological bottlenecks and provide solid scientific support for the refined management of nitrogen pollution in similar irrigation areas. Summary of the Invention

[0003] The purpose of this application is to provide a method, equipment, medium, and product for tracing the source of nitrates in water bodies by coupling nitrogen and oxygen isotopes and boron isotopes, which can improve the accuracy of water pollution source identification and provide a basis for regional water environment management and pollution control.

[0004] To achieve the above objectives, this application provides the following solution: In a first aspect, this application provides a method for sourcing nitrates in water using nitrogen and oxygen isotopes coupled with boron isotope tracing, comprising: Water samples and samples from different pollution sources were collected at sampling points set up in the study area according to the hydrological cycle; the sampling points covered different pollution source types and migration paths; Pre-treatment of water samples and samples from different pollution sources yields water treatment information. The water treatment information was measured using a stable isotope ratio mass spectrometer and a multi-receiver inductively coupled plasma mass spectrometer, respectively, to obtain the measurement information; the measurement information included: nitrate nitrogen and oxygen isotope data and boron isotope data. Based on the MixSIAR model, the contribution rate of different pollution sources to nitrate in water is calculated according to the nitrate nitrogen and oxygen isotope data, and the nitrate contribution rate of different endmembers is obtained. The MixSIAR model is a model constructed using a Bayesian mixture model to quantify the contribution of each pollution source to nitrate, with nitrate nitrogen and oxygen isotope data as a tracer index of nitrate sources in water. Based on the nitrate contribution rates of different end-members, an end-member mixing model is used to distinguish pollution flows with similar nitrogen and oxygen isotope fingerprints according to the boron isotope data, so as to quantify the contribution ratio of sewage and manure.

[0005] Secondly, this application provides a computer device, including: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the above-described method for tracing nitrates in water using nitrogen and oxygen isotopes and boron isotopes.

[0006] Thirdly, this application provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the above-described method for tracing nitrates in water using coupled nitrogen and oxygen isotopes and boron isotopes.

[0007] Fourthly, this application provides a computer program product, including a computer program that, when executed by a processor, implements the above-described method for tracing nitrates in water using coupled nitrogen and oxygen isotopes and boron isotopes.

[0008] According to the specific embodiments provided in this application, the following technical effects are disclosed: This application provides a method, equipment, medium, and product for nitrate source identification in water bodies using coupled nitrogen and oxygen isotope and boron isotope tracers. The method utilizes a stable isotope ratio mass spectrometer and a multi-receiver inductively coupled plasma mass spectrometer to determine the isotope content of water treatment information. Based on the MixSIAR model, the contribution rate of different pollution sources to nitrate levels in water bodies is calculated based on nitrate nitrogen and oxygen isotope data, yielding the nitrate contribution rate of different endmembers. Furthermore, an endmember mixing model is employed to determine the contribution proportion of different pollution sources based on boron isotope data, enabling the differentiation and quantification of pollution sources. Building upon quantitative source tracing based on nitrogen and oxygen dual isotopes, this application introduces boron isotopes as tracers, which is beneficial because livestock manure and wastewater have similar nitrogen and oxygen isotope ratios but significantly different boron isotope ratios. This allows for accurate identification of the contributions of livestock manure and wastewater, significantly improving the accuracy of nitrogen pollution source identification in water bodies and providing a scientific basis for regional water environment management and pollution control. Attached Figure Description

[0009] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0010] Figure 1 A flowchart for a method of tracing the source of nitrates in water using nitrogen and oxygen isotopes and boron isotopes; Figure 2 This is a spatiotemporal distribution map of nitrate, nitrogen, and oxygen isotopes in section A of the main stream of a certain river; among which... Figure 2 (a) represents the δ of the water body in section A of the main stream of a certain river. 15 N-NO3 - Spatiotemporal distribution map; Figure 2 (b) represents the δ of the water body in section A of the main stream of a certain river. 18 O-NO3 - Spatiotemporal distribution map; Figure 3 δ of the water body in section A of the main stream of a certain river 15 N-NO3 - With δ 18 O-NO3 - Relationship diagram; Figure 4 This is a schematic diagram comparing the contributions of various pollution sources to nitrate levels during the dry and wet seasons based on the MixSIAR model; among them, Figure 4 (a) in the figure is a schematic diagram comparing the contributions of various pollution sources to nitrate during the dry season based on the MixSIAR model; Figure 4(b) in the figure is a schematic diagram comparing the contributions of various pollution sources to nitrate during the high-water season based on the MixSIAR model; Figure 5 For δ 11 A schematic diagram illustrating the source analysis of B isotopes in manure and sewage nitrates; Figure 6 This is a schematic diagram of the structure of a computer device provided in an embodiment of this application. Detailed Implementation

[0011] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0012] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0013] In one exemplary embodiment, such as Figure 1 As shown, a method for tracing the source of nitrates in water using nitrogen and oxygen isotopes and boron isotopes is provided, comprising: Step 100: Collect water samples and samples from different pollution sources at sampling points set up within the study area according to the hydrological cycle. The sampling points cover different types of pollution sources and their migration paths.

[0014] Step 200: Pre-treat water samples and samples from different pollution sources to obtain water treatment information.

[0015] In one embodiment, water samples and samples from different pollution sources are pretreated to obtain water treatment information, specifically including: Water samples and samples from different pollution sources were acidified after passing through a 0.45µm filter membrane to obtain water treatment information.

[0016] Step 300: Isotope measurements of the water treatment information are performed using a stable isotope ratio mass spectrometer and a multi-receiver inductively coupled plasma mass spectrometer, respectively, to obtain the measurement information. The measurement information includes nitrate nitrogen and oxygen isotope data and boron isotope data.

[0017] The water treatment information was analyzed by isotopic determination using a stable isotope ratio mass spectrometer and a multi-receiver inductively coupled plasma mass spectrometer, respectively, to obtain the following information: The nitrate nitrogen and oxygen isotopes of the samples in the water treatment information were determined using a stable isotope ratio mass spectrometer to obtain nitrate nitrogen and oxygen isotope data.

[0018] Boron isotope measurements were performed on water samples from the water treatment information using a multi-receiver inductively coupled plasma mass spectrometer to obtain boron isotope data.

[0019] As an optional implementation method, a stable isotope ratio mass spectrometer is used to determine the nitrate nitrogen and oxygen isotopes of the samples in the water treatment information to obtain nitrate nitrogen and oxygen isotope data, specifically including: Nitrate nitrogen in the sample was converted to N2O using a specific denitrifying bacteria method; N2O was collected and concentrated using a Trace-Gas instrument; the concentrated gas was passed into a continuous-flow stable isotope ratio mass spectrometer to determine the nitrogen and oxygen isotope characteristic values ​​in N2O; using USGS32, USGS34, and USGS35 as standards, the detection results of nitrogen and oxygen isotope characteristic values ​​were corrected using a two-point correction method to obtain nitrate nitrogen and oxygen isotope data.

[0020] Boron isotope analysis was performed on water samples from the water treatment information using a multi-receiver inductively coupled plasma mass spectrometer (ICP-MS) to obtain boron isotope data, specifically including: The water sample in the water treatment information was separated and enriched using boron-specific resin. The resin was activated sequentially with dilute nitric acid, ultrapure water, and dilute ammonia. The water sample was then passed through the resin column at a rate of 1 mL / min to allow for full adsorption of boron. Impurity ions were removed by rinsing with ultrapure water. The adsorbed boron was desorbed with dilute nitric acid, the desorbed liquid was collected, evaporated and concentrated, and finally diluted to volume with dilute nitric acid.

[0021] Boron isotope ratios in separated and enriched water samples were determined using a multi-receiver inductively coupled plasma mass spectrometer (MRP-MS). The separated and enriched water samples underwent evaporation, atomization, and ionization to form a boron ion beam. After mass separation using the electromagnetic field of the MRP-MS, the ions were simultaneously received by a multi-receiver array. 11 B and 10 The ion current signal of B will 11 B / 10 The B ratio is calculated by comparing it with a preset standard substance to obtain the δ value. 11 The boron isotope composition results, represented by the B value, ultimately yield boron isotope data.

[0022] Step 400: Based on the MixSIAR model, calculate the contribution rate of different pollution sources to nitrate in the water body according to nitrate nitrogen and oxygen isotope data, and obtain the nitrate contribution rate of different endmembers. The MixSIAR model is a Bayesian mixture model constructed using nitrate nitrogen and oxygen isotope data as tracer indicators of nitrate sources in the water body to quantify the contribution of each pollution source to nitrate.

[0023] The mathematical expression corresponding to the Bayesian mixture model is: .

[0024] .

[0025] .

[0026] .

[0027] in, For mixed samples medium isotope The value; As a source of pollution The contribution rate; The total number of pollution sources; The value of isotope j in pollution source k; As a source of pollution medium isotope Fractionation correction term; for The mean of a normal distribution; for The standard deviation of a normally distributed system; for The mean of a normal distribution; for The standard deviation of a normally distributed system; For residuals; for The standard deviation of the normal distribution it follows. It is used to correct the isotope fractionation effect that occurs during nitration, denitration, and other processes.

[0028] Step 500: Based on the nitrate contribution rates of different endmembers, an endmember mixing model is used to distinguish pollution flows with similar nitrogen and oxygen isotope fingerprints according to boron isotope data, so as to quantify the contribution ratio of sewage and manure.

[0029] The mathematical expression corresponding to the endmember hybrid model is: .

[0030] .

[0031] in, Data on boron isotopes in water samples; Characteristic data of end-members in livestock and poultry manure; Feature data for wastewater end-members; The percentage of contribution to pollution from livestock and poultry manure; The percentage of contribution to wastewater pollution.

[0032] This application identifies and spatially locates target water bodies to delineate pollution source areas with different characteristics; it systematically collects water samples and detects nitrate content and nitrogen-oxygen isotope ratio (δ¹⁸O). 15 N-NO3 - and δ 18 O-NO3 - ), boron isotopes (δ) 11 B) Ratio: The MixSIAR model was used to quantitatively calculate the contribution of nitrate from different sources, and boron isotopes were further used to separate the contributions of sewage and livestock manure. This application quantifies the contributions of different nitrogen pollution sources, such as agricultural fertilizers, soil organic nitrogen, livestock manure, and sewage. In particular, it overcomes the problem that traditional nitrogen and oxygen isotopes cannot distinguish the contributions of sewage and livestock manure, significantly improving the accuracy of nitrogen pollution source identification in water bodies and providing a scientific basis for regional water environment management and pollution control.

[0033] This application is traditionally based on nitrogen and oxygen diisotopes (δ¹⁸O). 15 N-NO3 - δ 18 O-NO3 - Based on quantitative tracing, boron isotopes (δ¹²) are introduced. 11 B) As a tracer, it is advantageous because livestock manure and sewage have similar nitrogen-oxygen isotope ratios and δ¹⁸O values. 11 B's significantly different features enabled accurate identification of the contributions of livestock and poultry manure and sewage.

[0034] In practical applications, the specific design process includes the following steps: S1. Set up sampling points within the study area to cover different pollution source types and migration paths as much as possible.

[0035] S2. Collect water samples and samples from different pollution sources in the study area and pre-treat them.

[0036] The collected water samples were acidified after passing through a 0.45µm filter membrane, thus completing the water sample collection and pretreatment.

[0037] S3. Nitrate nitrogen and oxygen isotopes and boron isotopes were determined using an isotope ratio mass spectrometer (IRMS) and a multi-collector inductively coupled plasma mass spectrometer (MC-ICPMS), respectively.

[0038] The determination of nitrogen and oxygen isotopes using a stable isotope ratio mass spectrometer includes the following steps: δ in nitrate 15 N-NO3 - and δ 18 O-NO3 - The determination was performed using the denitrifying bacteria method, which includes the following steps: (1) Nitrate in the sample is converted into N2O by specific denitrifying bacteria; (2) N2O is collected and concentrated by Trace-Gas instrument; (3) The concentrated gas is passed into a continuous flow isotope ratio mass spectrometer to identify the nitrogen and oxygen isotope characteristic values ​​in N2O; (4) The detection results are corrected by using USGS32, USGS34 and USGS35 as standard samples and combining the two-point correction method.

[0039] Nitrate pollution source apportionment methods based on nitrogen and oxygen stable isotopes rely on the δ-coefficients between different sources. 15 N and δ 18 Significant differences in O values: δ of atmospheric deposition 15 The N value ranges from -7.5‰ to -8‰, with a mean of -4.3‰, and δ 18 The O value was relatively high, ranging from 26.5‰ to 73.8‰; the δ values ​​of manure and wastewater were... 15 N ranged from 5.9‰ to 22‰ and from 4.6‰ to 18.4‰, with average values ​​of 12.7‰ and 11.4‰, respectively; nitrate δ produced by soil organic nitrogen mineralization 15 N ranges from 0‰ to 11‰, with a mean of 4.7‰, δ 18 O is influenced by both water and atmospheric oxygen, ranging from -10‰ to 10‰; the δ of ammonium nitrogen and nitrate nitrogen in chemical fertilizers 15 N values ​​were -8.2‰ to 5‰ and -4‰ to 6.5‰, respectively, and the δ of nitrate nitrogen fertilizer... 18 The concentration of oxygen (O) ranged from 13.5‰ to 22.7‰. Isotopic characteristic spectra of different pollution sources were established, and the δ¹⁸O values ​​of water samples from sampling points were analyzed. 15 N-NO3 - With δ 18 O-NO3 - By comparing the measured values ​​with those of sewage, the source of pollution can be qualitatively identified. For example, if the isotope value of the sample falls within the characteristic range of manure and sewage, it indicates that nitrate pollution in the area mainly originates from such emissions.

[0040] The determination of boron isotope ratios using MC-ICPMS includes the following steps: The filtered water sample was adjusted to pH 8.5–9.5 and then separated and enriched using Amberlite IRA-743 boron-specific resin. The resin was activated sequentially with dilute nitric acid, ultrapure water, and dilute ammonia. The water sample was then passed through the resin column at a rate of 1 mL / min to ensure sufficient boron adsorption. Impurity ions were removed by rinsing with ultrapure water. Subsequently, the adsorbed boron was desorbed with dilute nitric acid, and the eluent was collected, evaporated, concentrated, and finally diluted to volume with dilute nitric acid for boron isotope ratio determination. The pretreated water sample was then introduced into an inductively coupled plasma source, where it underwent evaporation, atomization, and ionization to form a boron ion beam. After mass separation using an electromagnetic field, the beam was simultaneously received using a multi-receiver array. 11 B and 10 The ion current signal of B is used to accurately determine its intensity ratio. The sample... 11 B / 10 The B ratio was calculated by comparing it with international standard reference materials to obtain the δ value. 11 The B value represents the boron isotope composition.

[0041] S4. Using the MixSIAR toolkit, the nitrogen and oxygen stable isotope ratios from different sources were input into the stable isotope mixing model for calculation to obtain the nitrate contribution rate of different endmembers; δ 15 N-NO3 - and δ 18 O-NO3 - The value was used as a tracer indicator of the source of nitrate in water to construct a MixSIAR model.

[0042] The nitrate nitrogen-oxygen isotope ratio data of water samples were compiled into a .csv file and named consumer. The endmember mean values ​​of different pollution sources were compiled into a .csv file and named source. A .csv file with the same row and column names as source but with 0 data was named discrimination.

[0043] The compiled files were imported into the MixSIAR model, and the contribution rate of different pollutant endmembers to nitrate was obtained after verifying the model results.

[0044] The contribution rate of nitrate pollution sources in water samples is quantified using a Bayesian mixture model in R. The expression for the Bayesian mixture model is as follows: .

[0045] .

[0046] .

[0047] .

[0048] Calculated using the MixSIAR model; Follows a normal distribution , Follows a normal distribution , Residuals represent the undetermined variables between different water samples. Follows a normal distribution 0 represents the average value.

[0049] S5. Combining boron isotope data, further distinguish and quantify the relative contributions of livestock and poultry manure and sewage.

[0050] Using boron isotope data, an endmember mixing model was constructed to distinguish the contribution ratios of livestock and poultry manure and sewage in fecal wastewater. The expression of the model is as follows: .

[0051] .

[0052] The contribution of livestock and poultry manure pollution and the contribution of wastewater pollution to the output water samples were calculated using the coefficient of determination R. 2 The model was validated using residual analysis; the actual proportion of livestock and poultry manure pollution sources and the actual proportion of sewage pollution sources were obtained by multiplying the model by the contribution ratio of livestock and poultry manure.

[0053] By inputting nitrate nitrogen and oxygen isotope data into a Bayesian mixture model (MixSIAR toolkit), the contribution rate of different endmembers (such as agricultural fertilizers, soil organic nitrogen, livestock manure, and sewage) to nitrate pollution can be scientifically calculated. Based on this, boron isotope data is further used to distinguish between livestock manure and sewage, making the model's output contribution rate results more reliable and significantly reducing errors caused by overlapping endmember features, thus laying the foundation for accurate assessment of nitrate pollution load. Traditionally, methods based on nitrate nitrogen and oxygen isotope tracing perform well in distinguishing sources such as agricultural fertilizers and soil organic nitrogen, but when distinguishing between livestock manure and sewage, which are both organic pollution sources, their isotopic features may overlap, leading to decreased identification accuracy. This application creatively introduces boron isotope (δ¹⁰)... 11 B) As a tracer, livestock manure and sewage have significant differences in boron isotope composition (where sewage has a δ¹⁸O₅). 11 B ranges from -7.7‰ to 12.9‰, and the δ of animal manure... 11 (B ranges from 6.9‰ to 42.1‰), which can effectively compensate for the shortcomings of nitrogen and oxygen isotope source tracing methods, and achieve accurate differentiation and quantification of these two important pollution sources (livestock and poultry manure and sewage), making the quantitative analysis of nitrate pollution sources more accurate.

[0054] Thirteen sampling points were selected from section A of a certain river main stream and 23 sampling points in the Hetao Irrigation District (including the main canal, main drainage canal, branch drainage canals and a certain freshwater sea area). Sampling was carried out during the dry season (May) and the wet season (August). The pollution characteristics and source contributions of nitrate were systematically analyzed by comprehensively using hydrochemical analysis, stable isotope tracing and Bayesian mixture model (MixSIAR).

[0055] The nitrate concentration in the study area ranged from 0.01 mg / L to 2.60 mg / L. This concentration range was generally below the Class III limit of the Surface Water Environmental Quality Standard (10 mg / L, expressed as nitrogen), indicating that there was no widespread exceedance of nitrate concentrations in the area. However, significant spatial and temporal variations in concentration were observed, which resulted from the combined effects of differences in the intensity of input from various pollution sources and complex aquatic environmental processes.

[0056] The source was traced using the nitrogen-oxygen stable isotope ratio of nitrates. δ 15 N-NO3 - The value distribution is extremely wide, ranging from -2.06‰ to 23.26‰; δ 18 O-NO3 - The values ​​also vary significantly, ranging from -13.17‰ to 20.96‰, which may be due to the diversity of nitrate sources and complex biogeochemical processes. Figure 2 This is a spatiotemporal distribution map of nitrate, nitrogen, and oxygen isotopes in section A of the main stream of a river. Figure 2 (a) represents the δ of the water body in section A of the main stream of a certain river. 15 N-NO3 - Spatiotemporal distribution map; Figure 2 (b) represents the δ of the water body in section A of the main stream of a certain river. 18 O-NO3 - Spatiotemporal distribution map. Spatially, the nitrate content and isotope values ​​in the irrigation area are higher than those in the main stream of a certain river; temporally, there are significant differences in nitrate content and isotope values ​​between the dry and wet seasons. This spatiotemporal heterogeneity reflects not only the uneven spatial distribution of pollution sources, such as stronger sewage sources near the irrigation area's drainage, but also the influence of seasonal changes in hydrological conditions, which regulate the dilution and migration of pollutants, as well as the rate of biogeochemical processes such as denitrification.

[0057] δ 18 O-NO3 - With δ 15 N-NO3 - Perform dual isotope analysis. Figure 3 δ of the water body in section A of the main stream of a certain river 15 N-NO3 - With δ 18 O-NO3 -The relationship diagram shows a clear linear distribution of data points, with a fitting slope ranging from 1.3 to 2.1. This slope range is much higher than the theoretical slope of pure nitrification, confirming the existence of significant denitrification in the water. Denitrification is the process by which microorganisms reduce nitrate to nitrogen or nitrous oxide. This process preferentially consumes nitrate molecules containing light isotopes, resulting in a decrease in the concentration of nitrate in the remaining nitrate. 15 N and 18 Enrichment of O.

[0058] To quantify the contribution of different pollution sources to nitrate levels in water bodies, a MixSIAR model based on a Bayesian statistical framework was used for systematic analysis. Based on regional pollution source characteristics, five end-members were established: atmospheric deposition, chemical fertilizers (further distinguished into nitrate and ammonium nitrogen fertilizers), soil organic nitrogen, and a mixture of "sewage / manure". The nitrogen and oxygen isotope eigenvalues ​​(δ¹⁸O⁻) of each end-member were analyzed. 15 N and δ 18 O) Based on data reported in multiple studies for similar environments, the parameters were set and localized for adjustment. Specifically: atmospheric deposition (δ) 15 N: 3.2±2.4‰, δ 18 O: 44.0±9.1‰), nitrate nitrogen fertilizer (δ 15 N: 0.9±2.0‰, δ 18 O: 19.2±4.9‰), ammonium nitrogen fertilizer (δ 15 N: 0.2±0.8‰, δ 18 O: -0.6±1.6‰), soil organic nitrogen (δ 15 N: 5.0±1.4‰, δ 18 O: 3.0±1.7‰) and wastewater / manure mixed source (δ 15 N: 16.3±5.7‰, δ 18 O: 7.0±2.7‰). The model not only inputs the mean of each endmember, but also integrates their standard deviation to characterize the internal variation of the source and measurement uncertainty, thus making the contribution rate estimation more robust.

[0059] The quantization results of the MixSIAR model reveal significant spatiotemporal differentiation patterns. Figure 4 This is a schematic diagram comparing the contributions of various pollution sources to nitrate levels during the dry and wet seasons based on the MixSIAR model. Figure 4 (a) in the figure is a schematic diagram comparing the contributions of various pollution sources to nitrate during the dry season based on the MixSIAR model; Figure 4Figure (b) shows a schematic diagram comparing the contributions of various pollution sources to nitrate during the wet season based on the MixSIAR model. Spatially, the drainage canal system within the irrigation area exhibits distinct pollution characteristics, with the mixed source of manure / sewage making the most significant contribution, averaging as high as 51.4% during the dry season and still reaching 36.2% during the wet season, although decreasing slightly. This result directly confirms the strong impact of increased organic fertilizer application and domestic wastewater discharge on surface water bodies through the irrigation and drainage network. Furthermore, the contribution of soil organic nitrogen remains stable and significant (approximately 20%-30%) across different seasons, reflecting the continuous release of background nitrogen from agricultural soils. The contribution of atmospheric deposition shows a higher rate in the main stream than in the canal system, with a slight increase during the wet season, reflecting its widespread use as a non-point source input. The overall contribution of chemical fertilizers is relatively low. Figure 2 and Figure 4 In this context, YR stands for river, GC stands for canal, PG stands for drain, and WLSH stands for freshwater sea area.

[0060] The "sewage / manure" endmember in the above model is still a mixture of the two. To achieve more refined source analysis, this application innovatively introduces boron isotopes (δ¹⁰). 11 B) As an auxiliary discrimination tool. Through δ... 11 The B-isotope tracing technology decomposed the contribution rates of manure and sewage (based on manure + sewage = 100%) output by the MixSIAR model. At multiple monitoring points, the contribution rate of livestock and poultry manure to sewage / manure ranged from 51.1% to 100%, while the contribution rate of sewage ranged from 0% to 48.9%. Figure 5 For δ 11 A schematic diagram illustrating the sources of nitrates from manure and wastewater using B isotopes. Spatially, the main stream of a certain river, as the receiving water body, receives nitrates from both upstream inflow and irrigation runoff. The contribution of wastewater / manure is mainly from manure (82.8%). The main canal, as the water diversion channel, sees manure contributing 72.9% of the wastewater / manure contribution. The drainage canal, as the collection channel for farmland runoff, has the highest contribution rate from manure, accounting for 89.6% of the wastewater / manure contribution. This fully demonstrates the process of significant nitrogen loss through irrigation runoff after manure application in agricultural production within the irrigation area.

[0061] In one exemplary embodiment, a computer device is provided, which may be a server or a terminal, and its internal structure diagram may be as follows. Figure 6As shown, the computer device includes a processor, memory, input / output (I / O) interfaces, and a communication interface. The processor, memory, and I / O interfaces are connected via a system bus, and the communication interface is also connected to the system bus via the I / O interfaces. The processor provides computational and control capabilities. The memory includes non-volatile storage media and internal memory. The non-volatile storage media stores the operating system, computer programs, and a database. The internal memory provides the environment for the operation of the operating system and computer programs stored in the non-volatile storage media. The database stores data on the source of nitrates in water using nitrogen, oxygen, and boron isotope tracing. The I / O interfaces are used for exchanging information between the processor and external devices. The communication interface is used for communication with external terminals via a network connection. When the computer program is executed by the processor, it implements a method for source of nitrates in water using nitrogen, oxygen, and boron isotope tracing.

[0062] Those skilled in the art will understand that Figure 6 The structure shown is merely a block diagram of a portion of the structure related to the present application and does not constitute a limitation on the computer device to which the present application is applied. Specific computer devices may include more or fewer components than those shown in the figure, or combine certain components, or have different component arrangements.

[0063] In one exemplary embodiment, a computer device is also provided, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the steps in the above-described method embodiments.

[0064] In one exemplary embodiment, a computer-readable storage medium is provided storing a computer program that, when executed by a processor, implements the steps in the above-described method embodiments.

[0065] In one exemplary embodiment, a computer program product is provided, including a computer program that, when executed by a processor, implements the steps in the above-described method embodiments.

[0066] It should be noted that the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data used for analysis, data stored, data displayed, etc.) involved in this application are all information and data authorized by the user or fully authorized by all parties, and the collection, use and processing of the relevant data must comply with relevant regulations.

[0067] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium, and when executed, it can include the processes of the embodiments of the above methods. Any references to memory, databases, or other media used in the embodiments provided in this application can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM can take many forms, such as Static Random Access Memory (SRAM) or Dynamic Random Access Memory (DRAM).

[0068] The databases involved in the embodiments provided in this application may include at least one type of relational database and non-relational database. Non-relational databases may include, but are not limited to, blockchain-based distributed databases. The processors involved in the embodiments provided in this application may be general-purpose processors, central processing units, graphics processing units, digital signal processors, programmable logic devices, data processing logic devices, etc., and are not limited to these.

[0069] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0070] This document uses specific examples to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the methods and core ideas of this application. Furthermore, those skilled in the art will recognize that, based on the ideas of this application, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A method of coupling nitrogen and oxygen isotope and boron isotope tracers of nitrate sources in water bodies, characterized in that, include: Water samples and samples from different pollution sources were collected at sampling points set up in the study area according to the hydrological cycle. The sampling points cover different types of pollution sources and migration paths; Pre-treatment of water samples and samples from different pollution sources yields water treatment information. The water treatment information was measured using a stable isotope ratio mass spectrometer and a multi-receiver inductively coupled plasma mass spectrometer, respectively, to obtain the measurement information; the measurement information included: nitrate nitrogen and oxygen isotope data and boron isotope data. Based on the MixSIAR model, the contribution rate of different pollution sources to nitrate in water is calculated according to the nitrate nitrogen and oxygen isotope data, and the nitrate contribution rate of different endmembers is obtained. The MixSIAR model is a model constructed using a Bayesian mixture model to quantify the contribution of each pollution source to nitrate, with nitrate nitrogen and oxygen isotope data as a tracer index of nitrate sources in water. Based on the nitrate contribution rates of different end-members, an end-member mixing model is used to distinguish pollution flows with similar nitrogen and oxygen isotope fingerprints according to the boron isotope data, so as to quantify the contribution ratio of sewage and manure.

2. The method for tracing the source of nitrates in water using coupled nitrogen and oxygen isotopes and boron isotopes according to claim 1, characterized in that, Pretreatment of water samples and samples from different pollution sources yields water treatment information, specifically including: Water samples and samples from different pollution sources were acidified after passing through a 0.45µm filter membrane to obtain water treatment information.

3. The method for tracing the source of nitrates in water using coupled nitrogen and oxygen isotopes and boron isotopes according to claim 1, characterized in that, The water treatment information was analyzed by isotopic determination using a stable isotope ratio mass spectrometer and a multi-receiver inductively coupled plasma mass spectrometer, respectively, to obtain the determination information, including: The nitrate nitrogen and oxygen isotopes of the samples in the water treatment information were determined using a stable isotope ratio mass spectrometer to obtain nitrate nitrogen and oxygen isotope data. Boron isotope measurements were performed on water samples from the water treatment information using a multi-receiver inductively coupled plasma mass spectrometer to obtain boron isotope data.

4. The method for tracing the source of nitrates in water using coupled nitrogen and oxygen isotopes and boron isotopes according to claim 3, characterized in that, The nitrate nitrogen and oxygen isotopes of the samples in the water treatment information were determined using a stable isotope ratio mass spectrometer, and the nitrate nitrogen and oxygen isotope data were obtained, specifically including: Nitrate nitrogen in the sample was converted into N2O using a specific denitrifying bacteria method. N2O was collected and concentrated using a Trace-Gas instrument; The concentrated gas was passed into a continuous flow stable isotope ratio mass spectrometer to determine the nitrogen and oxygen isotope characteristic values ​​in N2O. Using USGS32, USGS34, and USGS35 as standard samples, the detection results of nitrogen and oxygen isotope characteristic values ​​were corrected by combining the two-point correction method to obtain nitrate nitrogen and oxygen isotope data.

5. The method for tracing the source of nitrates in water using coupled nitrogen and oxygen isotopes and boron isotopes according to claim 3, characterized in that, Boron isotope analysis was performed on water samples from the water treatment information using a multi-receiver inductively coupled plasma mass spectrometer (ICP-MS) to obtain boron isotope data, specifically including: The water sample in the water treatment information was separated and enriched using boron-specific resin. The resin was activated sequentially with dilute nitric acid, ultrapure water and dilute ammonia. The water sample was then passed through the resin column at a rate of 1 mL / min to allow for full adsorption of boron. Impurity ions were removed by rinsing with ultrapure water. The adsorbed boron was desorbed with dilute nitric acid, the desorbed liquid was collected, evaporated and concentrated, and finally diluted to volume with dilute nitric acid. The boron isotope ratio of the separated and enriched water sample is determined by using a multi-receiving inductively coupled plasma mass spectrometer; wherein the separated and enriched water sample is evaporated, atomized and ionized based on the multi-receiving inductively coupled plasma mass spectrometer to form a boron ion beam; after mass separation by the electromagnetic field of the multi-receiving inductively coupled plasma mass spectrometer, the ion flow signals of B and B are simultaneously received by using a multi-receiver array 11 B and 10 B 11 B 10 B ratio is compared and calculated with a preset standard substance, and a boron isotope composition result expressed by δ 11 B value is obtained, and finally boron isotope data is obtained.

6. The method for tracing the source of nitrates in water using coupled nitrogen and oxygen isotopes and boron isotopes according to claim 1, characterized in that, The mathematical expression corresponding to the Bayesian mixture model is: ； ； ； ； in, For mixed samples medium isotope The value; As a source of pollution The contribution rate; The total number of pollution sources; The value of isotope j in pollution source k; As a source of pollution medium isotope Fractionation correction term; for The mean of a normal distribution; for The standard deviation of a normally distributed system; for The mean of a normal distribution; for The standard deviation of a normally distributed system; For residuals; for The standard deviation of the normal distribution it follows.

7. The method for tracing the source of nitrates in water using coupled nitrogen and oxygen isotopes and boron isotopes according to claim 1, characterized in that, The mathematical expression corresponding to the endmember hybrid model is: ； ； in, Data on boron isotopes in water samples; Characteristic data of end-members in livestock and poultry manure; Feature data for wastewater end-members; The percentage of contribution to pollution from livestock and poultry manure; The percentage of contribution to wastewater pollution.

8. A computer device, comprising: A memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that the processor executes the computer program to implement the method for nitrate source in water with coupled nitrogen and oxygen isotope and boron isotope tracing as described in any one of claims 1-7.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that, When executed by a processor, the computer program implements the method for nitrate source in water using coupled nitrogen and oxygen isotope and boron isotope tracing as described in any one of claims 1-7.

10. A computer program product, comprising a computer program, characterized in that, When executed by a processor, the computer program implements the method for nitrate source in water using coupled nitrogen and oxygen isotope and boron isotope tracing as described in any one of claims 1-7.

Images