Agricultural non-point source pollution abatement monitoring and evaluation method based on entropy weight comprehensive pollution index

Abstract

The invention discloses an agricultural non-point source pollution abatement monitoring and evaluation method based on an entropy weight comprehensive pollution index, and belongs to the field of agricultural pollution abatement. The method comprises the following steps: determining monitoring point positions, monitoring frequencies and monitoring indexes of each treatment project according to a monitoring thought of pollution source-conveying path-receiving water area; a single-factor evaluation method and a comprehensive pollution index method are adopted to perform quantitative analysis on the pollution control effect, and an entropy weight method is combined to calculate the pollution removal rate, so that the effect of the pollution control project is evaluated. The method can be used for various agricultural non-point source pollution treatment scenes such as livestock and poultry breeding pollution treatment and aquaculture pollution treatment, and the scientificity and accuracy of pollution treatment monitoring are improved.

Description

Technical Field

[0001] The present invention belongs to the field of agricultural pollution control, relates to agricultural environmental monitoring and pollution control evaluation, and specifically relates to an agricultural non-point source pollution control monitoring and evaluation method based on an entropy weight comprehensive pollution index. Background Art

[0002] Agricultural non-point source pollution is a major environmental issue facing the sustainable development of agriculture in the Yangtze River Basin and even globally. Current agricultural pollution control methods mostly rely on engineering measures, such as anaerobic field restoration, ex situ fermentation, and oxidation ponds. However, how to scientifically monitor their effectiveness remains an urgent issue. Currently, commonly used pollution assessment methods include single-factor assessment and comprehensive pollution index methods. However, these methods fail to fully consider the relative importance of pollution factors, resulting in low accuracy and scientificity of the assessment results. Therefore, a scientific and reasonable monitoring and evaluation method is urgently needed to improve the ability to analyze the effectiveness of agricultural non-point source pollution control and provide a scientific basis for agricultural pollution control decision-making. Summary of the Invention

[0003] The present invention aims to provide a method for monitoring and evaluating agricultural non-point source pollution control based on an entropy-weighted comprehensive pollution index to address the limitations of existing technologies in evaluating pollution control effectiveness. The core of this method is to use entropy weights to determine the relative importance of pollution factors and combine single-factor evaluation methods with a comprehensive pollution index method to form a more scientific and reasonable pollution control effectiveness evaluation system.

[0004] The purpose of the present invention is achieved through the following technical solutions:

[0005] A monitoring and evaluation method for agricultural non-point source pollution control based on an entropy weight comprehensive pollution index comprises the following steps:

[0006] (1) Determine the monitoring locations, frequency and indicators for agricultural non-point source pollution control projects;

[0007] (2) Use the single factor evaluation method to independently evaluate each pollution factor;

[0008] (3) Use the comprehensive pollution index method to calculate the pollution index of each pollutant before and after treatment;

[0009] (4) Calculate the weight factor of pollution control effect based on the entropy weight method and conduct weighted comprehensive evaluation;

[0010] (5) Conduct a graded assessment of the pollution reduction effect of the treatment project based on the calculation results.

[0011] In step (1), the monitoring points are arranged according to the characteristics of "pollution source - transport route - receiving water area" of agricultural non-point source pollution, including livestock and poultry breeding areas, irrigated farmland, aquaculture areas and receiving water areas. The monitoring frequency can be set according to the implementation stage of the pollution control project, including baseline surveys before treatment, dynamic monitoring during treatment implementation and long-term follow-up monitoring after treatment. The monitoring indicators include but are not limited to key pollutants such as total nitrogen (TN), ammonium nitrogen (NH4+-N), chemical oxygen demand (COD), total phosphorus (TP) and suspended solids (SS).

[0012] In step (2), the single factor evaluation method is used to evaluate the pollution degree by calculating the multiples of each pollutant exceeding the standard.

[0013] Single factor evaluation method: used to calculate the excess multiples of each pollution factor. The calculation formula is:

[0014] P (i) =C (i) / S (i) (Formula 1)

[0015] in:

[0016] P (i) is the single factor evaluation index of the i-th pollution factor;

[0017] C (i) is the measured concentration of the i-th pollution factor;

[0018] S (i) is the evaluation standard value of the i-th pollution factor (for example, the Class III water quality standard in the "Surface Water Environmental Quality Standard" GB3838-2002).

[0019] In step (3), the comprehensive pollution index method is used to calculate the pollution index before and after treatment, and the pollution treatment effect is compared and analyzed.

[0020] Comprehensive pollution index method (based on entropy weight method): This method integrates the data of various monitoring indicators and uses the entropy weight method to assign weights to each indicator to obtain a weighted comprehensive pollution index. The calculation steps and formula are as follows:

[0021] (a) Normalization

[0022] Construct a judgment matrix A consisting of m monitoring points and n pollution indicators. ij ), normalize the index data to get the matrix R:

[0023] R ij =a ij / (∑ (i＝1) m a ij ) (Formula 2)

[0024] (b) Calculating information entropy

[0025] For the jth pollution index, calculate its information entropy H j :

[0026]

[0027] where k = 1 / ln(m);

[0028] (c) Determine weights

[0029] Determine the weight ωj of the jth indicator according to the information entropy value:

[0030]

[0031] (d) Calculation of comprehensive pollution index

[0032] Single factor evaluation index P of each monitoring point (ij) After weighting (obtained from formula 1), the comprehensive pollution index P is:

[0033]

[0034] In step (4), the removal rate of each pollutant is calculated, and the corresponding weights of different pollution factors are assigned by the entropy weight method; the weighted pollution removal rate is calculated to form the final pollution control effect evaluation result.

[0035] 1) Calculation of removal rate

[0036] The calculation formula for the pollution removal rate Q of each treatment project is:

[0037] Q = (c in – c out ) / c in × 100% (Formula 6)

[0038] Where: c in is the pollutant concentration at the project inlet, c in It is the pollutant concentration at the outlet after treatment.

[0039] 2) Weighted pollution removal rate

[0040] Calculate the removal rate Qj of each pollutant separately, and then weight the removal rate of each pollutant according to the weight ωj obtained by the entropy weight method to obtain the final weighted pollution removal rate:

[0041]

[0042] In step (5), the governance effect is graded and evaluated: based on the calculation results, the governance effect is divided into categories such as "significant improvement", "general improvement", and "poor effect", and an optimized governance plan is proposed.

[0043] The method of the present invention is applicable to the effect evaluation of pollution control processes such as anaerobic land restoration, ectopic fermentation, oxidation ponds, and "three ponds and two dams".

[0044] The evaluation results of the method of the present invention can be used to optimize the design of pollution control projects and improve the efficiency and effect of pollution control.

[0045] The method of the present invention can be applied to the Yangtze River Basin and other areas where agricultural non-point source pollution is relatively serious, providing a scientific basis for agricultural environmental management.

[0046] The method of the present invention can be applied to various agricultural non-point source pollution control scenarios such as livestock and poultry breeding pollution control and aquaculture pollution control. It can improve the scientificity and accuracy of pollution control monitoring and promote the further development of agricultural pollution control technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 Schematic diagram of the layout of 11 monitoring points for the construction of ecologically clean small watersheds for agricultural non-point source pollution control in Shaanxi, Henan and Hubei provinces by 2024. DETAILED DESCRIPTION

[0048] The following examples are used to further illustrate the present invention, but should not be construed as limiting the present invention. Unless otherwise specified, the technical means used in the examples are conventional means well known to those skilled in the art.

[0049] Example 1

[0050] This example selects 11 ecological clean small watersheds to be built in Shaanxi, Henan and Hubei provinces in 2024 ( Figure 1 ) as an example, the method proposed in this invention was used to evaluate the removal of major pollutants in water before and after treatment. Monitoring indicators included total nitrogen (TN), total phosphorus (TP), chemical oxygen demand (COD), ammonium nitrogen (NH₄⁻⁻N), and suspended solids (SS). Table 1 below provides the monitoring data (all in mg / L).

[0051] Table 1

[0052]

[0053] In addition, the Class III water body standard in the "Surface Water Environmental Quality Standard" is used as the evaluation standard, and its specified values are shown in Table 2 below.

[0054] Table 2

[0055]

[0056] 1. Single factor evaluation method calculation

[0057] (1) The formula for calculating the excess multiple of each pollutant is:

[0058] P (i) =C (i) / S (i)

[0059] Among them, C (i) is the actual concentration of a pollutant, S (i) is the standard value corresponding to the pollutant. To illustrate the problem, here we only use the data after treatment to calculate the pollution index to reflect the improvement of the treatment effect. For example:

[0060] For TN:P TN =0.869 / 1.0=0.869;

[0061] For TP:P TP =0.063 / 0.2=0.315;

[0062] For COD:P COD =42.5 / 20.0=2.125;

[0063] For NH4 + -N:

[0064] For SS:P SS =20.1 / 25.0=0.804.

[0065] (2) It can be seen from the above results that after treatment, some indicators in the water body have dropped below the standard, but some indicators (such as COD) still exceed the standard.

[0066] 2. Calculation of pollution removal rate

[0067] The removal rate Q of each pollutant is calculated using the following formula:

[0068] Q=(c in –c out ) / c in ×100%

[0069] The specific calculation is as follows:

[0070] For TN:

[0071] For TP:

[0072] For COD:

[0073] For NH4+-N:

[0074] For SS:

[0075] 3. Calculate weighted pollution removal rate using entropy weight method

[0076] In order to further integrate the treatment effects of each pollutant, this embodiment introduces the entropy weight method to calculate the weight of each indicator. First, normalize the data of each indicator and construct the data matrix A = (a ij )(where i is the monitoring point number and j is the pollution index number), the normalization formula is: Since this embodiment processes regional average data, assuming that the fluctuation of each indicator among multiple monitoring points is small, after normalization and information entropy calculation, the weight of each indicator is obtained as follows:

[0077] ω TN =0.20,ω TP =0.25,ω COD =0.15, ω SS =0.15.

[0078] Weighted pollution removal rate Q weighted The calculation formula is:

[0079] Substitute the removal rate values of each indicator and calculate:

[0080] Q weighted =0.20×45.1%+0.25×74.8%+0.15×41.0%+0.25×69.9%+0.15×55.6%≈59.69%.

[0081] 4. Final evaluation results

[0082] Through the above data processing and calculations, the final weighted pollution removal rate was approximately 59.7%. This indicates that through the use of a combination of treatment processes such as anaerobic soil restoration, ex situ fermentation, and oxidation ponds, the overall water body's main pollutants were significantly reduced. Among them, the removal of TN, NH₄⁺-N, and TP was particularly effective. The comprehensive evaluation results show that the treatment effect met the expected requirements and the overall water quality tended to improve.

[0083] The method of the present invention can be widely used in the field of agricultural non-point source pollution control, providing data support for environmental management and policy formulation.

[0084] The above embodiments are only used to help illustrate the present invention. The implementation methods of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. A method for monitoring and evaluating agricultural non-point source pollution control based on entropy weight comprehensive pollution index, characterized in that: The following steps are involved: (1) Determine the monitoring locations, frequency and indicators for agricultural non-point source pollution control projects; (2) Use the single factor evaluation method to independently evaluate each pollution factor; (3) Use the comprehensive pollution index method to calculate the pollution index of each pollutant before and after treatment; (4) Calculate the weight factor of pollution control effect based on the entropy weight method and conduct weighted comprehensive evaluation; (5) Conduct a graded assessment of the pollution reduction effect of the treatment project based on the calculation results.

2. The method for monitoring and evaluating agricultural non-point source pollution control according to claim 1, wherein: In step (1), the monitoring points are arranged according to the main transmission routes of agricultural non-point source pollution, including livestock and poultry breeding areas, irrigated farmland, aquaculture areas and receiving waters.

3. The method for monitoring and evaluating agricultural non-point source pollution control according to claim 1, wherein: In step (1), the monitoring frequency is set according to the implementation stage of the pollution control project, including a baseline survey before treatment, dynamic monitoring during treatment implementation, and long-term follow-up monitoring after treatment.

4. The method for monitoring and evaluating agricultural non-point source pollution control according to claim 1, wherein: In step (1), the monitoring indicators include total nitrogen, ammonium nitrogen, chemical oxygen demand, total phosphorus, and suspended solids.

5. The method for monitoring and evaluating agricultural non-point source pollution control according to claim 1, wherein: In step (2), the calculation formula of the single factor evaluation method is: P (i) =C (i) / S (i) ; Where: P (i) is the single factor evaluation index of the i-th pollution factor, C (i) is the measured concentration of the i-th pollution factor, S (i) is the evaluation standard value of the i-th pollution factor.

6. The method for monitoring and evaluating agricultural non-point source pollution control according to claim 1, characterized in that: In step (3), the calculation steps and formula of the comprehensive pollution index method are as follows: (a) Normalization Construct a judgment matrix A consisting of m monitoring points and n pollution indicators. ij ), normalize the index data to get the matrix R: (b) Calculate the information entropy for the jth pollution index and calculate its information entropy H j : where k = 1 / ln(m); (c) Determine weights Determine the weight ω of the jth indicator according to the information entropy value j : (d) Calculation of comprehensive pollution index Single factor evaluation index P of each monitoring point (ij) After weighting, the comprehensive pollution index P is:

7. The method for monitoring and evaluating agricultural non-point source pollution control according to claim 1, characterized in that: In step (4), the removal rate of each pollutant is calculated, and the corresponding weights of different pollution factors are assigned by the entropy weight method; Calculate the weighted pollution removal rate to form the final pollution control effect evaluation result; 1) Calculation of removal rate The calculation formula for the pollution removal rate Q of each treatment project is: Q=(c in –c out ) / c in ×100% Where: c in is the pollutant concentration at the project inlet, c in The pollutant concentration at the outlet after treatment; 2) Weighted pollution removal rate Calculate the removal rate Q for each pollutant j , and then the weight ω obtained by the entropy weight method j , weight the removal rates of each pollutant to obtain the final weighted pollution removal rate:

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