An integrated environmental nitrogen threshold assessment method and system

Abstract

The application provides a comprehensive environmental nitrogen threshold evaluation method and system, and relates to the technical field of environmental nitrogen threshold evaluation. The steps of the method comprise the following steps: identifying main nitrogen pollution problems; selecting nitrogen threshold standards corresponding to each pollution problem; obtaining a preliminary evaluation value based on monitoring data and model simulation; correcting the preliminary evaluation value to obtain a corrected evaluation value; comparing the corrected value with the threshold value, calculating the emission reduction amount; and outputting the emission reduction target and suggestions or recording the compliance state. The application improves the accuracy of the evaluation result and the scientificity of the management decision.

Description

Technical Field

[0001] This invention relates to the field of environmental nitrogen threshold assessment technology, and in particular to a comprehensive environmental nitrogen threshold assessment method and system. Background Technology

[0002] The extensive use of chemical nitrogen fertilizers is an important means of increasing grain yield, but the irrational application of nitrogen fertilizers has led to a series of environmental problems, such as eutrophication of water bodies, increased greenhouse gas emissions, soil acidification, excessive nitrates in groundwater, and loss of biodiversity, seriously threatening human health and sustainable socio-economic development. Current research on environmental nitrogen thresholds is relatively limited, mainly focusing on nitrogen deposition and surface water nitrogen pollution, and suffers from problems such as single research indicators and a lack of systematic and comprehensive approaches.

[0003] In Chinese patent application CN201410442797.0, a method for calculating the nitrogen input threshold in farmland is disclosed. This method includes the following steps: comparative planting and statistical data collection; determining the yield nitrogen threshold for farmland crops and the environmental nitrogen input threshold for farmland using the statistical results; determining the farmland soil type and classifying soil fertility levels based on the crop yield nitrogen threshold and the regional farmland environmental nitrogen input threshold, and correcting the determined nitrogen input threshold; finally, calculating the farmland nitrogen input threshold. This technology only considers the farmland nitrogen input threshold and does not comprehensively consider the environmental impact of nitrogen loss, and it lacks systematicity and comprehensiveness. Furthermore, this technology does not cover the entire process across multiple media (atmosphere, water, and soil) and lacks a universal quantitative correction mechanism. Summary of the Invention

[0004] To overcome the shortcomings of existing technologies, the purpose of this invention is to provide a comprehensive method and system for assessing environmental nitrogen thresholds, which effectively improves the accuracy of assessment results and the scientific nature of management decisions.

[0005] To achieve the above objectives, the present invention provides the following solution:

[0006] A comprehensive method for assessing environmental nitrogen thresholds includes:

[0007] Identify the main nitrogen pollution problems based on the environmental characteristics and current pollution status of the target area;

[0008] For each of the nitrogen pollution problems mentioned, the corresponding nitrogen threshold standard CL(i) is selected based on the preset environmental quality standards and literature research; where i represents the i-th indicator;

[0009] Preliminary evaluation values ​​N for each indicator were obtained using monitoring data and model simulation. pre (i);

[0010] For the preliminary assessment value N pre(i) Perform correction to obtain the corrected evaluation value N. cor (i);

[0011] The corrected evaluation value N cor (i) Compare with the nitrogen threshold standard CL(i) corresponding to the threshold, and calculate the nitrogen load emission reduction E(i) for each indicator;

[0012] If E(i) > 0, output the corresponding emission reduction targets and recommended measures for each item; if E(i) = 0, record it as a compliance status.

[0013] Preferably, the major nitrogen pollution problems include: atmospheric nitrogen deposition, total nitrogen load in surface water, nitrate in groundwater, atmospheric ammonia emissions, and nitrous oxide emissions.

[0014] Preferably, for each of the aforementioned nitrogen pollution problems, a corresponding nitrogen threshold standard CL(i) is selected based on preset environmental quality standards and literature research, including:

[0015] The atmospheric nitrogen deposition threshold CL(1) was calculated using the steady-state mass balance method.

[0016] The total nitrogen concentration was set at 1.0 mg·L⁻¹, which is Class III in the pre-set surface water environmental quality standards. -1 Based on the benchmark, the total nitrogen load threshold CL(2) for surface water was determined by combining representative watershed monitoring data;

[0017] The nitrate limit of 10 mg / L is set in the pre-defined drinking water hygiene standards. -1 The groundwater nitrate threshold CL(3) was determined based on this benchmark.

[0018] 3 μg·m -3 The atmospheric NH3 threshold CL(4) was determined.

[0019] Based on the non-CO2 greenhouse gas emission reduction requirements corresponding to the preset 2℃ temperature control target, the target of reducing emissions by 30% in 2050 relative to 2020 is converted into the annual allowable emission limit to determine the atmospheric N2O threshold CL (5).

[0020] Preferably, preliminary evaluation values ​​N for each indicator are obtained using monitoring data and model simulation. pre (i), including:

[0021] Retrieve real-time monitoring records from monitoring stations and download meteorological fields, land use, and emission inventories that match the target area;

[0022] The WRF-CMAQ coupled model is invoked to perform simulations based on the meteorological field, land use, and emission inventory to obtain gridded deposition fluxes. These fluxes are then integrated along administrative or watershed boundaries to obtain a preliminary assessment value N for atmospheric nitrogen deposition. pre(1);

[0023] For rivers with monitoring sections, the amount of nitrogen entering the river is calculated by multiplying the average flow rate by the total nitrogen concentration;

[0024] For sub-basins without monitoring sections, the emission inventory method is used to summarize agricultural, domestic and industrial source emissions and deduct nitrogen reduction coefficients to obtain the summary data;

[0025] The amount of nitrogen entering the river is added to the total data to obtain a preliminary assessment value N for surface water. pre (2);

[0026] Nitrate concentration data from monitoring wells were collected, and a regional representative value was calculated using the area-weighted average method. This regional representative value was then multiplied by the annual groundwater turnover to obtain a preliminary assessment value N for groundwater nitrate. pre (3); Among them, due to the lack of data on annual groundwater renewal, the actual relationship between agricultural nitrogen surplus and groundwater nitrate concentration is expressed.

[0027] The emission inventories of agricultural ammonia and livestock farming are retrieved, and the results are summed cell-by-cell on the GIS platform to obtain a preliminary assessment value of atmospheric NH3, N. pre (4);

[0028] By calling the EDGAR v7.0 database, the annual N2O emissions of the target area are extracted to obtain a preliminary assessment value of atmospheric N2O. pre (5).

[0029] Preferably, for the preliminary evaluation value N pre (i) Perform correction to obtain the corrected evaluation value N. cor (i), including:

[0030] Preliminary assessment value Compared with independent measured data Unify them to the same time scale and spatial unit to form one-to-one matching data pairs;

[0031] right Outlier removal is performed using box plots to remove outliers;

[0032] According to the formula Calculate system deviation ;

[0033] According to the formula Calculate the correction factor ;

[0034] when season ;

[0035] According to the correction factor and preliminary assessment values Generate corrected evaluation values ;in, ;

[0036] Randomly select no less than 20% of the total comparison data as the validation set, and repeat the cross-validation ten times; if the root mean square error If the decrease is less than 1% in two consecutive iterations, stop the iteration and confirm. ;in, n is the number of data pairs in the validation set. For the first Corrected evaluation values ​​for each sample For the first Independent measured data for each sample;

[0037] When the RMSE of the validation set does not exceed the preset threshold, output the corrected evaluation value after validation. Otherwise, return to step "for". Outlier removal is performed using a box plot method to remove outliers, and quality control is re-executed and iterated until the preset threshold is met.

[0038] Preferably, the corrected evaluation value N cor (i) Compare with the nitrogen threshold standard CL(i) corresponding to the threshold, and calculate the nitrogen load emission reduction E(i) for each indicator, including:

[0039] According to the formula The corrected evaluation value N cor (i) is subtracted from the nitrogen threshold standard CL(i) corresponding to the threshold to obtain the difference value. ;

[0040] According to the formula Determine nitrogen load emission reduction .

[0041] Preferably, it further includes:

[0042] When i=3, meaning i corresponds to the groundwater nitrate index, assuming that the decrease in groundwater nitrate concentration is directly proportional to the decrease in agricultural nitrogen surplus, according to the formula... Calculate agricultural nitrogen surplus emission reduction ;in Let p be the agricultural nitrogen surplus of the p-th province or watershed. Let m be the average nitrate concentration in the p-th province or river basin, and m be the number of provinces or river basins. The calculated value is... Used to replace E(i).

[0043] A comprehensive environmental nitrogen threshold assessment system includes:

[0044] The nitrogen pollution identification unit is used to identify major nitrogen pollution problems based on the environmental characteristics and current pollution status of the target area.

[0045] The threshold selection unit is used to select the corresponding nitrogen threshold standard CL(i) for each nitrogen pollution problem, referring to the preset environmental quality standards and literature research; where i represents the i-th indicator.

[0046] The preliminary assessment unit is used to obtain preliminary assessment values ​​N for each indicator using monitoring data and model simulation. pre (i);

[0047] The correction processing unit is used to process the initial evaluation value N. pre (i) Perform correction to obtain the corrected evaluation value N. cor (i);

[0048] The emission reduction calculation unit is used to calculate the corrected evaluation value N. cor (i) Compare with the nitrogen threshold standard CL(i) corresponding to the threshold, and calculate the nitrogen load emission reduction E(i) for each indicator;

[0049] The result output unit is used to output the emission reduction targets and recommended measures for the corresponding indicators if E(i)>0; if E(i)=0, it is recorded as the compliance status.

[0050] The present invention discloses the following technical effects:

[0051] (1) By introducing a correction process, this invention systematically corrects the preliminary assessment values ​​of various nitrogen pollution indicators in simulation or monitoring, significantly improving the accuracy of environmental nitrogen load assessment and avoiding the problem of misjudgment of emission reduction caused by factors such as model input errors and insufficient data representativeness. Compared with existing methods that directly use model results or inventory calculation values ​​as the basis, this invention provides a quantifiable and verifiable correction mechanism, ensuring the scientificity and reliability of subsequent threshold comparisons and policy decisions.

[0052] (2) The present invention constructs a unified multi-indicator evaluation process, which integrates nitrogen pollution problem identification, threshold selection, simulation evaluation, data correction, emission reduction calculation and treatment suggestion output into a system. It solves the problem of independent evaluation and logical separation of multiple pollution indicators in the prior art, and is particularly suitable for the integrated management needs of large-scale areas (such as provinces and river basins).

[0053] (3) The present invention uses measured values ​​aligned with national monitoring data as the basis for correction, which has strong operability and data adaptability. It can be flexibly deployed at different time scales (years, seasons) and spatial units (administrative regions, sub-basins), which enhances the dynamic updating capability and regional adaptability of the environmental management system and effectively responds to the multi-source and ever-changing pollution pattern.

[0054] (4) The “threshold-correction-emission reduction” coupling method proposed in this invention improves the accuracy and target decomposition ability of nitrogen pollution control strategies. In particular, it introduces a correction mechanism that links agricultural nitrogen surplus with concentration in the case of hidden pollution such as groundwater nitrate, filling the technical gap that existing methods cannot accurately correspond to the quantitative relationship between the source and the medium response. It has significant environmental benefits and promotion prospects. Attached Figure Description

[0055] To more clearly illustrate the technical solutions in the embodiments of the present invention 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 the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0056] Figure 1 A flowchart of the method provided in an embodiment of the present invention;

[0057] Figure 2 This is a schematic diagram of the system structure provided in an embodiment of the present invention. Detailed Implementation

[0058] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0059] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0060] Figure 1 The method flowchart provided in the embodiments of the present invention is as follows: Figure 1 As shown, the present invention provides a comprehensive method for assessing environmental nitrogen thresholds, comprising:

[0061] Step 100: Identify the main nitrogen pollution problems based on the environmental characteristics and current pollution status of the target area;

[0062] Step 200: For each nitrogen pollution problem, select the corresponding nitrogen threshold standard CL(i) based on the preset environmental quality standards and literature research; where i represents the i-th indicator;

[0063] Step 300: Obtain preliminary evaluation values ​​N for each indicator using monitoring data and model simulation. pre (i);

[0064] Step 400: For the preliminary evaluation value N pre (i) Perform correction to obtain the corrected evaluation value N. cor (i);

[0065] Step 500: Adjust the corrected evaluation value N cor (i) Compare with the nitrogen threshold standard CL(i) corresponding to the threshold, and calculate the nitrogen load emission reduction E(i) for each indicator;

[0066] Step 600: If E(i) > 0, output the emission reduction targets and recommended measures for the corresponding indicators; if E(i) = 0, record it as a compliance status.

[0067] Specifically, the problems selected in step 100 of this embodiment include: atmospheric nitrogen deposition, total nitrogen load in surface water, nitrate in groundwater, atmospheric NH3, and atmospheric N2O.

[0068] Optionally, step 200 in this embodiment includes:

[0069] Step 201: The nitrogen deposition threshold is estimated using the steady-state mass balance method, referring to existing literature (Duan Lei. Study on the boundary load zoning of acid deposition in China [D]. Beijing: Tsinghua University, 2000.). The calculation formula is as follows:

[0070]

[0071]

[0072]

[0073]

[0074]

[0075] In the formula, CL(S), CL(N), CL max (N), CL nut (N) represents the sulfur deposition threshold, nitrogen deposition threshold, acidified nitrogen threshold, and nutrient nitrogen threshold, respectively. BC * dep (BC = Ca) 2+ + Mg 2+ + Na + + K + ) represents the amount of basic cations deposited after sea salt correction; BC w Bc represents the rate at which soil weathering produces basic cations. u (Bc = Ca) 2+ + Mg 2+ + K + ) represents the rate at which plants absorb basic cations; Ni The nitrogen mineralization rate; N u The rate at which plants absorb nitrogen; N de The rate of nitrogen denitrification; f de For denitrification rate; N le,crit Critical nitrogen leaching rate; ANC le,crit The critical alkalinity leaching rate. These are intermediate calculation parameters used to calculate the nitrogen acidification threshold.

[0076] Step 202: Surface water nitrogen load threshold: According to my country's existing quality standard "Surface Water Environmental Quality Standard" (GB3838-2002), Class III water standard, 1.0 mg / L... -1 Confirmed. Based on existing literature (Yu CQ, Huang X, Chen H, et al. Managing nitrogen to restore water quality in China [J]. Nature, 2019, 567(7749): 516-520.), the total nitrogen load threshold for surface water in each province was determined empirically, i.e., the threshold was set when the total nitrogen concentration in a representative watershed of each province first reached 1.0 mg L⁻¹. -1 Total nitrogen load for the year;

[0077] Step 203: The nitrate level in groundwater is set at the nitrate limit of 10 mg / L as specified in my country's "Standards for Drinking Water Quality" (GB5749-2022). -1 (N) is used as the threshold standard.

[0078] Step 204: Since my country currently does not have a quality standard for atmospheric NH3 concentration, the standard set forth in the Convention on Long-Distance Transboundary Air Pollution, which aims to protect higher plant communities and their ecological functions, is 3 μg / m³. -3 The critical level of NH3.

[0079] Step 205: The atmospheric N2O threshold is mainly based on my country's established emission reduction strategy under the Paris Agreement's temperature control target. According to existing literature (Institute of Climate Change and Sustainable Development of Tsinghua University. China's long-term low-carbon development strategies and pathways [M]. Singapore: Springer, 2022.) on the current status, future emission scenarios, and outcomes of non-CO2 greenhouse gas emissions, to achieve the 2°C temperature control target, N2O emissions need to be reduced by 30% by 2050 compared to 2020.

[0080] Optionally, step 300 in this embodiment includes:

[0081] Step 301: The current atmospheric nitrogen deposition is simulated using the coupled air quality model WRF-CMAQ (Community Multiscale Air Quality Modeling System - Weather Research and Forecasting). The model parameters are set according to the actual conditions of the target area, and source emission inventories and meteorological data are input to simulate nitrogen deposition in the target area for the target year. For example, major anthropogenic emission sources include agricultural sources, industrial sources, power plant sources, residential sources, mobile sources, dust sources, biomass combustion sources, and solvent use sources.

[0082] Step 302: The current total nitrogen load in surface water is obtained using the emission inventory method. This method estimates the nitrogen budget flux of the system by acquiring activity data and relevant emission coefficients, and analyzes the sources and destinations of nitrogen in the system. Nitrogen load flowing into water bodies includes agricultural runoff, grassland runoff, forest runoff, nitrogen deposition, sewage discharge, and human and animal excrement discharge. Nitrogen inputs involved in the calculation mainly include biological fixation, chemical fertilizers, atmospheric deposition, and food and feed imports; nitrogen outputs mainly include NH3 volatilization, output to water bodies, food and feed output, and biomass combustion emissions.

[0083] Step 303: Estimate the agricultural nitrogen surplus by subtracting the amount of nitrogen absorbed by crops from the total nitrogen input to farmland. Nitrogen input to farmland includes chemical fertilizers, organic fertilizers, nitrogen deposition, biological nitrogen fixation, and straw return to the field. Nitrogen absorbed by crops includes nitrogen absorbed by crop grains and nitrogen absorbed by straw.

[0084] Step 304: The current atmospheric NH3 emissions are derived from the 2019 high-resolution NH3 emission inventory of my country compiled by the National Key Research and Development Program project "High-efficiency control technology for ammonia emissions from agriculture and animal husbandry" (data not published). The estimation of NH3 emissions from farmland is based on existing literature (Wang C, Liu ZH, Zhang XM, et al. Managing Ammonia for Multiple Benefits Based on Verified High-Resolution Emission Inventory in China [J]. Environ. Sci. Technol. 2025, 59(10): 5131-5144). NH3 emissions from livestock and poultry farming, industrial sources, natural sources, aquaculture sources, grassland sources, and other sources can be estimated using the Human-Nature Coupled System (CHANS) developed in existing literature (GuB J, Ju XT, Chang J, et al. Integrated reactive nitrogen budgets and future trends in China [J]. Proceedings of the National Academy of Sciences of the United States of America, 2015, 112(28): 8792-8797.).

[0085] Step 305: Current atmospheric N2O emissions were obtained from the Emissions Database for Global Atmospheric Research (EDGAR v7.0).

[0086] Further, step 400 of this embodiment includes:

[0087] Step 401: Perform spatiotemporal alignment to unify the model simulation output with the independent observation data to a consistent time scale and spatial unit. Specifically, this embodiment uses a double-key indexing method composed of geographic unit codes and timestamps to match and bind data pairs, ensuring that each preliminary evaluation value corresponds one-to-one with a unique measured data point.

[0088] Step 402: To address the potential for extreme values ​​in the measured data, a box plot-based outlier removal mechanism is employed for quality control. Specifically, this embodiment calculates the first quartile, third quartile, and interquartile range of the measured data, automatically identifying and removing outliers below the lower bound or above the upper bound. Simultaneously, the removed data is recorded in an outlier log for subsequent manual review or retrospective adjustment. Compared to the traditional fixed threshold method, this method offers advantages such as strong adaptability and applicability to different distribution patterns.

[0089] Step 403: After data cleaning, this embodiment performs system bias estimation and correction coefficient calculation. This embodiment calculates the difference between the preliminary assessment value and the observed value for each item, and takes their arithmetic mean as the system bias. Then, by subtracting the system bias from the preliminary assessment value and dividing by the preliminary assessment value, the correction coefficient for the corresponding index is generated. To prevent division by zero due to a zero preliminary assessment value, this embodiment sets a zero protection mechanism, directly setting the correction coefficient to 1 in this case. This strategy is simple to calculate, converges stably, and is suitable for unified correction processing of multiple nitrogen pollution indicators.

[0090] Step 404: To improve the stability and generalization ability of the correction coefficients, this embodiment designs a cross-validation and self-terminating mechanism. Specifically, this embodiment randomly selects no less than 20% of the samples from all alignment data pairs to form a validation set, repeats ten rounds of cross-validation, and calculates the root mean square error after each round. When the error decreases by less than 1% for two consecutive rounds, this embodiment automatically terminates the iteration, determining that the correction process has converged and stabilized. This strategy avoids the overfitting problem that may occur in traditional fixed-round validation.

[0091] Step 405: After calibration, this embodiment continues with the result judgment and quality backtracking process. If the root mean square error in the validation set does not exceed a preset threshold, this embodiment confirms the calibration is effective and uses the calibrated evaluation value as the final result for subsequent nitrogen load emission reduction calculations. If the error exceeds the threshold range, this embodiment returns to the outlier removal step to re-execute data cleaning and calibration calculations until the result meets the accuracy requirements. This closed-loop processing method ensures that every evaluation result output by this embodiment has sufficient credibility.

[0092] Furthermore, step 500 of this embodiment includes:

[0093] Step 501: First, read the corrected assessment value obtained in the previous stage and retrieve the corresponding nitrogen threshold standard. Compare the two one by one, and perform a differential calculation of "current status minus threshold" for each indicator to identify whether the indicator is in an excessive state. This differential operation is a rigid judgment, which directly reflects the absolute difference between the corrected actual nitrogen load and the target threshold, and is a prerequisite for subsequent emission reduction quantification.

[0094] Step 502: After the difference result is generated, this embodiment immediately performs a positive / negative judgment: if the difference is positive, it means that the indicator has exceeded the threshold and emission reduction needs to be implemented; if the difference is zero or negative, it is considered to meet the standard. In the case of exceeding the standard, this embodiment directly confirms the difference value as the nitrogen load emission reduction requirement of the indicator, and retains its original unit without conversion, so as to ensure a traceable consistency with the threshold standard.

[0095] Step 503: To avoid negative numbers interfering with subsequent summary analysis, this embodiment introduces a "non-negation" logic when recording emission reductions: the difference between compliant indicators is automatically set to zero, and only the positive difference between exceeding indicators is retained. This allows decision-makers to intuitively see the pollution items that need to be prioritized for treatment, while also reducing the repetitive display of redundant data in subsequent reports.

[0096] Step 504: When the index number is three, corresponding to the groundwater nitrate concentration, this embodiment adopts an agricultural source-driven replacement algorithm. This embodiment assumes that the reduction in groundwater nitrate concentration is linearly related to the reduction in agricultural nitrogen surplus in each province or watershed: first, the agricultural nitrogen surplus of each province in the previous year is statistically analyzed, and then combined with the annual average concentration of groundwater nitrate in the same province, the potential surplus reduction contribution of each province is calculated; then, the summation is performed on all provinces to obtain the total surplus that can be reduced. This total amount directly replaces the original difference as the final emission reduction target for the groundwater nitrate index, thereby realizing the precise governance approach of source-media linkage.

[0097] Step 505: After completing the above processing, this embodiment writes the emission reduction amount, compliance status, and (if applicable) agricultural surplus replacement value for each indicator into the result cache area for subsequent result output and governance measure matching unit to call. Through the combination of differential judgment, nonnegation processing, and source-end replacement mechanism, this embodiment achieves differentiated emission reduction calculation for special media while ensuring simple and efficient operation, fully solving the shortcomings of existing technologies in accurately tracing the source and quantifying the treatment needs of groundwater nitrate.

[0098] As an optional implementation, step 600 of this embodiment includes:

[0099] Step 601: Based on the emission reduction results calculated in the previous stage, first determine whether the emission reduction of each indicator is greater than zero. This determination serves as the entry condition for the logical branch, distinguishing between two processing paths: indicators exceeding the standard and indicators that have met the standard, thereby achieving targeted management of different pollution control statuses. This branch determination is direct and executable, and is a prerequisite for subsequently generating control recommendations and forming compliance records.

[0100] Step 602: For indicators judged to be exceeding the standard, i.e., when the emission reduction is greater than zero, this embodiment directly uses the emission reduction as the sub-item treatment target for the pollution indicator, and simultaneously matches the corresponding treatment measure list in the preset nitrogen pollution control knowledge base. This list automatically selects several recommended measures based on pollution type (such as ammonia volatilization, runoff into rivers, nitrate leaching, etc.) and regional attributes (such as arable land type, fertilization intensity, groundwater vulnerability, etc.), forming a structured "indicator-target-recommendation" ternary output format, which is convenient for policymakers and implementers to quickly reference.

[0101] Step 603: For indicators that have already met the standards, i.e., those with zero emission reductions, this embodiment records the corrected assessment value, the corresponding threshold, the determination result of a zero difference, and the processing timestamp into the compliance database. This database, as a component of the regional compliance file management module, is used to generate annual environmental quality reports, support the evaluation of governance effectiveness, and dynamically track indicators. These records do not generate emission reduction targets or include governance recommendations to avoid wasting resources.

[0102] Step 604: After the above branch outputs are completed, this embodiment packages and organizes the processing results of all indicators and pushes them to the output interface, including the reporting module, decision support terminal, or remote management platform. Through this result output mechanism, this embodiment realizes an integrated closed loop of pollutant identification, assessment, judgment, and response, ensuring that each emission reduction or compliance status has clear quantitative basis and supporting technical path, thereby improving the scientific nature, pertinence, and feasibility of environmental governance.

[0103] Corresponding to the above methods, such as Figure 2 As shown, this embodiment also provides a comprehensive environmental nitrogen threshold assessment system, including:

[0104] The nitrogen pollution identification unit is used to identify major nitrogen pollution problems based on the environmental characteristics and current pollution status of the target area.

[0105] The threshold selection unit is used to select the corresponding nitrogen threshold standard CL(i) for each nitrogen pollution problem, referring to the preset environmental quality standards and literature research; where i represents the i-th indicator.

[0106] The preliminary assessment unit is used to obtain preliminary assessment values ​​N for each indicator using monitoring data and model simulation. pre (i);

[0107] The correction processing unit is used to process the initial evaluation value N. pre (i) Perform correction to obtain the corrected evaluation value N. cor (i);

[0108] The emission reduction calculation unit is used to calculate the corrected evaluation value N. cor(i) Compare with the nitrogen threshold standard CL(i) corresponding to the threshold, and calculate the nitrogen load emission reduction E(i) for each indicator;

[0109] The result output unit is used to output the emission reduction targets and recommended measures for the corresponding indicators if E(i)>0; if E(i)=0, it is recorded as the compliance status.

[0110] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the systems disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the descriptions are relatively simple; relevant parts can be referred to the method section.

[0111] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. Furthermore, those skilled in the art will recognize that, based on the ideas of the present invention, 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 the present invention.

Claims

1. A comprehensive method for assessing environmental nitrogen thresholds, characterized in that, include: Based on the environmental characteristics and current pollution status of the target area, the main nitrogen pollution problems are identified; these main nitrogen pollution problems include: atmospheric nitrogen deposition, total nitrogen load in surface water, nitrate in groundwater, atmospheric ammonia emissions, and nitrous oxide emissions. For each of the nitrogen pollution problems mentioned, the corresponding nitrogen threshold standard CL(i) is selected based on the preset environmental quality standards and literature research; where i represents the i-th indicator; Preliminary evaluation values ​​N for each indicator were obtained using monitoring data and model simulation. pre (i); For the preliminary assessment value N pre (i) Perform correction to obtain the corrected evaluation value N. cor (i); The corrected evaluation value N cor (i) Compare with the nitrogen threshold standard CL(i) corresponding to the threshold, and calculate the nitrogen load emission reduction E(i) for each indicator; If E(i) > 0, output the emission reduction targets and recommended measures for the corresponding indicators; if E(i) = 0, record it as a compliance status. For the preliminary assessment value N pre (i) Perform correction to obtain the corrected evaluation value N. cor (i), including: The initial assessment value N pre (i) and independent measured data N obs (i) Unify to the same time scale and spatial unit to form one-to-one matching data pairs; For N obs (i) Perform outlier removal by using box plots to remove outliers; According to the formula Calculate system deviation B i ; According to the formula Calculate the correction factor k i ; When N pre When (i) = 0, let k i =1; According to the correction factor k i and preliminary assessment value N pre (i) Generate the corrected evaluation value N cor (i); where N cor (i)=k i ×N pre (i); Randomly select at least 20% of the comparison data pairs as the validation set, and repeat the cross-validation ten times; if the root mean square error (RMSE) decreases by less than 1% for two consecutive iterations, stop the iteration and confirm k. i ;in, n is the number of alignment pairs in the validation set. Let j be the corrected evaluation value of the j-th sample. For the j-th sample, there are independent measured data. When the RMSE of the validation set does not exceed the preset threshold, output the corrected evaluation value N after validation. cor (i), otherwise return to step "for N" obs (i) Perform outlier removal by using box plot method to remove outliers, and then re-execute outlier removal and iterate until the preset threshold is met; The corrected evaluation value N cor (i) Compare with the nitrogen threshold standard CL(i) corresponding to the threshold, and calculate the nitrogen load emission reduction E(i) for each indicator, including: According to the formula Δ i =N cor (i)-CL(i) will correct the evaluation value N cor (i) is subtracted from the nitrogen threshold standard CL(i) corresponding to the threshold to obtain the difference Δ. i ; According to the formula Determine the nitrogen load emission reduction E(i); When i = 3, meaning i corresponds to the groundwater nitrate index, assuming that the decrease in groundwater nitrate concentration is directly proportional to the decrease in agricultural nitrogen surplus, according to the formula... Calculate agricultural nitrogen surplus emission reduction R N ;where N sur (p) represents the agricultural nitrogen surplus of the p-th province or watershed, and c p Let R be the average nitrate concentration in the p-th province or watershed, and m be the number of provinces or watersheds. N Used to replace E(i).

2. The comprehensive environmental nitrogen threshold assessment method according to claim 1, characterized in that, For each of the aforementioned nitrogen pollution problems, referring to the preset environmental quality standards and literature research, the corresponding nitrogen threshold standard CL(i) is selected, including: The atmospheric nitrogen deposition threshold CL(1) was calculated using the steady-state mass balance method. The total nitrogen concentration is set at 1.0 mg / L, which is Class III in the preset surface water environmental quality standards. -1 Based on the benchmark, the total nitrogen load threshold CL(2) for surface water was determined by combining representative watershed monitoring data; The nitrate limit of 10 mg / L is set in the pre-defined drinking water hygiene standards. -1 The groundwater nitrate threshold CL(3) was determined based on this benchmark. 3 μg·m -3 The atmospheric NH3 threshold CL(4) was determined. Based on the non-CO2 greenhouse gas emission reduction requirements corresponding to the preset 2℃ temperature control target, the target of reducing emissions by 30% in 2050 relative to 2020 is converted into the annual allowable emission limit to determine the atmospheric N2O threshold CL (5).

3. The comprehensive environmental nitrogen threshold assessment method according to claim 1, characterized in that, Using monitoring data and model simulations, preliminary evaluation values ​​N for each indicator are obtained. pre (i), including: Retrieve real-time monitoring records from monitoring stations and download meteorological fields, land use, and emission inventories that match the target area; The WRF-CMAQ coupled model is invoked to perform simulations based on the meteorological field, land use, and emission inventory to obtain gridded deposition fluxes. These fluxes are then integrated along administrative or watershed boundaries to obtain a preliminary assessment value N for atmospheric nitrogen deposition. pre (1); For rivers with monitoring sections, the amount of nitrogen entering the river is calculated by multiplying the average flow rate by the total nitrogen concentration; For sub-basins without monitoring sections, the emission inventory method is used to summarize agricultural, domestic and industrial source emissions and deduct nitrogen reduction coefficients to obtain the summary data; The amount of nitrogen entering the river is added to the total data to obtain a preliminary assessment value N for surface water. pre (2); Nitrate concentration data from monitoring wells were collected, and a regional representative value was calculated using the area-weighted average method. This regional representative value was then multiplied by the annual groundwater turnover to obtain a preliminary assessment value N for groundwater nitrate. pre (3); The emission inventories of agricultural ammonia and livestock farming are retrieved, and the results are summed cell-by-cell on the GIS platform to obtain a preliminary assessment value of atmospheric NH3, N. pre (4); The EDGARv7.0 database was used to extract the annual N2O emissions for the target area, yielding a preliminary assessment value of atmospheric N2O. pre (5).

4. A comprehensive environmental nitrogen threshold assessment system, characterized in that, include: The nitrogen pollution identification unit is used to identify major nitrogen pollution problems based on the environmental characteristics and pollution status of the target area. The major nitrogen pollution problems include: atmospheric nitrogen deposition, total nitrogen load in surface water, nitrate in groundwater, atmospheric ammonia emissions, and nitrous oxide emissions. The threshold selection unit is used to select the corresponding nitrogen threshold standard CL(i) for each nitrogen pollution problem, referring to the preset environmental quality standards and literature research; where i represents the i-th indicator. The preliminary assessment unit is used to obtain preliminary assessment values ​​N for each indicator using monitoring data and model simulation. pre (i); The correction processing unit is used to process the initial evaluation value N. pre (i) Perform correction to obtain the corrected evaluation value N. cor (i); The emission reduction calculation unit is used to calculate the corrected evaluation value N. cor (i) Compare with the nitrogen threshold standard CL(i) corresponding to the threshold, and calculate the nitrogen load emission reduction E(i) for each indicator; The result output unit is used to output the emission reduction targets and recommended measures for the corresponding indicators if E(i) > 0; if E(i) = 0, it is recorded as a compliance status. For the preliminary assessment value N pre (i) Perform correction to obtain the corrected evaluation value N. cor (i), including: The initial assessment value N pre (i) and independent measured data N obs (i) Unify to the same time scale and spatial unit to form one-to-one matching data pairs; For N obs (i) Perform outlier removal by using box plots to remove outliers; According to the formula Calculate system deviation B i ; According to the formula Calculate the correction factor k i ; When N pre When (i) = 0, let k i =1; According to the correction factor k i and preliminary assessment value N pre (i) Generate the corrected evaluation value N cor (i); where N cor (i)=k i ×N pre (i); Randomly select at least 20% of the comparison data pairs as the validation set, and repeat the cross-validation ten times; if the root mean square error (RMSE) decreases by less than 1% for two consecutive iterations, stop the iteration and confirm k. i ;in, n is the number of alignment pairs in the validation set. Let j be the corrected evaluation value of the j-th sample. For the j-th sample, there are independent measured data. When the RMSE of the validation set does not exceed the preset threshold, output the corrected evaluation value N after validation. cor (i), otherwise return to step "for N" obs (i) Perform outlier removal by using box plot method to remove outliers, and then re-execute outlier removal and iterate until the preset threshold is met; The corrected evaluation value N cor (i) Compare with the nitrogen threshold standard CL(i) corresponding to the threshold, and calculate the nitrogen load emission reduction E(i) for each indicator, including: According to the formula Δ i =N cor (i)-CL(i) will correct the evaluation value N cor (i) is subtracted from the nitrogen threshold standard CL(i) corresponding to the threshold to obtain the difference Δ. i ; According to the formula Determine the nitrogen load emission reduction E(i); When i = 3, meaning i corresponds to the groundwater nitrate index, assuming that the decrease in groundwater nitrate concentration is directly proportional to the decrease in agricultural nitrogen surplus, according to the formula... Calculate agricultural nitrogen surplus emission reduction R N ;where N sur (p) represents the agricultural nitrogen surplus of the p-th province or watershed, and c p Let R be the average nitrate concentration in the p-th province or watershed, and m be the number of provinces or watersheds. N Used to replace E(i).

Images