A method and device for obtaining environmental benchmarks for land-based pollution sources entering the sea

Abstract

The present invention discloses a method and device for obtaining an environmental benchmark for land-based pollution sources entering the sea. By investigating and collecting data in a research sea area and a land catchment area, a standard index method and an equal-standard pollution load method are used to obtain main water quality exceeding standard indicators and main land-based pollution entering the sea indicators in the sea area, and a marine ecological health evaluation index system is constructed based on a pressure-state-response model. The frequency distribution method and the pressure-response method are used to derive the benchmark value according to the evaluation result, and the average value of the derived benchmark value data is used as the environmental benchmark recommended value for land-based pollutants entering the sea. The method not only avoids a large amount of monitoring data required to determine the reference state, but also introduces indicators for the emission and treatment of land-based pollution sources entering the sea to evaluate the marine ecological health state, which can better reflect the land-based pollution input situation in the research sea area, and provide a scientific basis for the quantitative control of land-based pollution input guided by the improvement of marine environmental quality.

Description

Technical Field

[0001] The present invention belongs to the technical field of marine environmental protection, and in particular relates to a method and device for obtaining an environmental benchmark for land-based pollution sources entering the sea. Background Art

[0002] The input of land-based pollutants is the main factor affecting the environmental quality of coastal waters. With the development of social economy, rivers and sewage outlets entering the sea have brought a large amount of nutrients such as nitrogen and phosphorus, which have destroyed the balance of the marine ecosystem and caused eutrophication problems in some coastal waters. It is necessary to control land-based pollutants entering the sea. The existing calculation method of environmental benchmark values ​​generally only processes and calculates the seawater environmental data in the study area, but does not take into account the impact of the adjacent land environment on the marine environment. There are also large differences between the land environment and the seawater environment, and the environmental data and related parameter indicators are also very different, making it difficult to form a comprehensive and complete land and ocean evaluation system. Therefore, in the face of regional differences, international evaluation standards, and the assessment of the control of major land-based pollutants entering the sea, there is still room for further resolution.

[0003] The Chinese patent with publication number CN112417649A discloses a method, device, equipment and storage medium for formulating a joint nutrient salt benchmark. The method requires the establishment of multiple alternative quantile regression models in advance, and the best quantile regression model is selected from the multiple alternative quantile regression models according to different management target indicators. The operation is relatively complicated, and the regression quantiles of the management target indicators are determined mainly by referring to foreign research cases, which is inconsistent with my country's current evaluation standard system and has low applicability.

[0004] Therefore, there is an urgent need to provide a method and device for obtaining environmental benchmarks for land-based marine pollution sources to solve the above-mentioned technical problems. Summary of the invention

[0005] In view of the problems existing in the prior art, the present invention provides a method and device for obtaining the environmental benchmark of land-based pollution sources entering the sea. By investigating and collecting data in the research sea area and land catchment area, the sea water quality evaluation and land-based pollution sources entering the sea are investigated and calculated. The standard index method and the equal standard pollution load method are used to identify the main water quality exceeding standard index and the main land-based pollution entering the sea index in the sea area, respectively. The marine ecological health evaluation index system is constructed based on the pressure-state-response model, and the frequency distribution method and the pressure-response method are used to derive the benchmark value according to the evaluation results. This method not only avoids the large amount of monitoring data required to determine the reference state, but also introduces the emission and governance indicators of land-based pollution sources entering the sea to evaluate the ecological health state of the sea area, which can better reflect the land-based pollution input in the research sea area, and provide a scientific basis for the control standards of the main land-based pollutants entering the sea, such as total nitrogen, total phosphorus and other nutrients in seawater, which is conducive to the connection between the indicators and standard values ​​of the "Seawater Quality Standard" and the "Surface Water Environmental Quality Standard", and provides a scientific basis for the quantitative control of land-based pollution input guided by the improvement of marine environmental quality.

[0006] The technical solution of the present invention is achieved in this way:

[0007] A method for obtaining an environmental benchmark for land-based pollution sources entering the sea, comprising the following steps:

[0008] S1. Divide the land catchment area of ​​the research sea area, the catchment area includes plain area, non-plain area and artificial diversion area; collect environmental data of the catchment area to obtain a land environmental data set; collect seawater environmental data of the research sea area to obtain a sea environmental data set;

[0009] S2. Evaluate the seawater quality in the research area, calculate the pollution index of different pollutants in the seawater by the standard index method and rank them, and obtain the seawater quality exceeding standard index;

[0010] Calculate the pollution discharge load of land-based pollutants entering the sea, calculate the equivalent pollution load of land-based pollutants entering the sea by the equivalent pollution load method and sort them, and obtain the indicators of land-based pollutants entering the sea;

[0011] The union of the obtained seawater quality exceeding standard index and the land-based pollutant inflow index is used as the pressure variable index for calculating the environmental benchmark of land-based pollutants inflow into the sea, and dissolved oxygen and chlorophyll a are used as response variable indexes;

[0012] S3. Construct a pressure-state-response model, evaluate the ecological health status of the study sea area through the pressure-state-response model, and obtain the evaluation results of the ecological health status of the study sea area;

[0013] S4. Based on the ecological health status assessment results, pressure variable indicators and response variable indicators of the study sea area, the frequency distribution method and pressure-response method are used to derive the baseline value for the study sea area;

[0014] S5. The average value of the baseline data obtained in S4 is used as the recommended environmental baseline value for land-based pollutants entering the sea.

[0015] Preferably, the division of the watershed area in the plain area is performed by automatically extracting and drawing the watershed area boundary through the ArcSWAT model;

[0016] The demarcation of the watershed in the non-plain area is done by manually extracting and drawing the boundaries of the watershed;

[0017] The artificial diversion area is an area where the natural drainage direction is affected by sewage interception and diversion. The boundary of the catchment area is drawn and corrected through the direction of the drainage network and artificial channels.

[0018] Specifically, the ArcSWAT model is the Soil Water and Assessment Tools model, which is a hydrological model widely used at the basin scale, and is often used to analyze hydrological processes and water resources management within the basin.

[0019] ArcSWAT model is used to automatically extract the watershed boundary in non-plain areas. The operation steps include loading the digital elevation model without depression (with an accuracy of no less than 30m), performing flow direction analysis, calculating the accumulated flow volume, setting thresholds, extracting the river network, specifying the total outlet and dividing the sub-basin, and drawing the watershed boundary.

[0020] Manual extraction of watershed boundaries in plain areas includes identifying ridges and valleys, extracting river channels and watersheds based on high-precision topographic maps (with an accuracy of no less than 1:100,000). In flat areas, extraction is performed with reference to roads, administrative boundaries, etc. Starting from the river mouth, along the watershed and back to the river mouth, the watershed boundaries are outlined.

[0021] For areas where the natural drainage direction is affected by sewage interception and diversion, the boundaries of the catchment area will be adjusted and corrected according to the direction of the drainage network, artificial channels, etc.

[0022] Preferably, the marine environment data set includes seawater environment quality data and biodiversity data;

[0023] The terrestrial environmental data set includes the pollution source discharge data into the sea in the catchment area and the pollution control data in the catchment area.

[0024] Specifically, the seawater environmental quality data collected in the research area include dissolved oxygen, permanganate index, ammonia nitrogen, nitrate, nitrite, total nitrogen, active phosphate, total phosphorus, active silicate, chlorophyll a and other indicators;

[0025] Biodiversity data include phytoplankton, zooplankton, and macrobenthic diversity;

[0026] The data on pollution sources discharged into the sea in the catchment area include industrial sources, urban life sources, rural life sources, livestock and poultry breeding sources, aquaculture sources, and agricultural planting sources;

[0027] The pollution control data of the catchment area include the centralized collection rate of urban domestic sewage, the rural domestic sewage treatment rate, the industrial wastewater discharge rate that meets the standards, population, land use, establishment of nature reserves and other information.

[0028] Preferably, in S2, the seawater quality of the research sea area is evaluated, and the pollution index of different pollutants in the seawater is calculated by the standard index method; specifically, it includes:

[0029] According to the seawater environmental quality data in the marine environment data set, the concentrations of different pollutants in seawater are obtained; the pollution index of different pollutants in seawater is obtained through the standard index calculation formula. The standard index calculation formula is as follows:

[0030]

[0031] Among them, P i is the pollution index of pollutant i in seawater. When the pollution index>1, it means it exceeds the standard. i The values ​​are arranged from large to small, and the pollutants corresponding to the top three pollution indices are selected as the indicators of seawater quality exceeding the standard;

[0032] C i is the concentration of pollutant i in seawater, in mg / L; S i It is the environmental quality standard of pollutant i in seawater, and the unit is mg / L.

[0033] Specifically, the pollutants corresponding to the top three pollution indices are selected as the main indicators of seawater quality exceeding the standard, and the number of pollutants corresponding to the specific selected pollution indices can be one or more.

[0034] Preferably, in S2, the pollution discharge load of land-based pollutants entering the sea is calculated and ranked, specifically including:

[0035] According to the emission data of pollution sources in the catchment area into the sea in the terrestrial environmental data set, the absolute emission of different pollutants is obtained; the equivalent pollution load of different pollutants is obtained through the equivalent pollution load calculation formula. The calculation formula of the equivalent pollution load is as follows:

[0036]

[0037] Among them, L jis the equivalent pollution load of pollutant j in any pollution source entering the sea in the catchment area, q j is the absolute emission of pollutant j, in tons / year, C oj is the evaluation standard of pollutant j, the unit is mg / L, L n is the equivalent pollution load of all pollution sources entering the sea in the catchment area, and n is the number of pollution sources entering the sea in the catchment area;

[0038] L j The values ​​are arranged from large to small, and the pollutants corresponding to the equivalent pollution loads of the top three pollutants are selected as indicators of land-based pollutants entering the sea.

[0039] There are many pollution sources in the catchment area, such as industrial sources, urban living sources, etc. Each pollution source contains a variety of pollutants. n The design and calculation are to facilitate a better understanding of the environmental conditions of the catchment area.

[0040] Specifically, the pollutants corresponding to the top three equivalent pollution loads are selected as the main indicators of land-based pollutants entering the sea, and the number of pollutants corresponding to the specific selected equivalent pollution loads can be one or more.

[0041] Preferably, in S3, a marine ecological health evaluation index system is established based on a pressure-state-response model, and the ecological health status of the research sea area is evaluated by the marine ecological health evaluation index system;

[0042] The marine ecological health assessment index system includes a pressure layer, a status layer, and a response layer.

[0043] Specifically, the pressure layer includes population density, proportion of urban land and pollutant load per unit area indicators; the state layer includes CODMn, TN, TP, phytoplankton diversity, zooplankton diversity and large benthic biodiversity indicators; the response layer includes urban domestic sewage centralized collection rate, rural domestic sewage treatment rate, industrial wastewater discharge rate and protected area grade indicators.

[0044] Preferably, according to each indicator contained in the pressure layer, the state layer, and the response layer, each indicator is divided into intervals, and the divided intervals are assigned values; according to the assigned values ​​corresponding to the intervals where the indicators are located, the assignment results are obtained, and then the weighted method or the equal weighted method is used to calculate the comprehensive scores of the assignment results of each indicator, and the ecological health status evaluation results of the research sea area are evaluated and obtained according to the comprehensive scores;

[0045] The ecological health status evaluation results include very healthy, healthy, sub-healthy, unhealthy, and pathological.

[0046] Specifically, the result of the assignment is the assignment corresponding to the interval in which the actual value of a certain indicator lies;

[0047] The weighting method is to give weight calculation to the corresponding value results of the indicators, and different weights can be given according to the degree of impact of different indicators on the environment;

[0048] The equal weight method is to give the same weight to the assignment results corresponding to all indicators for calculation, that is, to find the average, and give the same weight to different indicators;

[0049] The weighted method or equal-weighted method can set reasonable weights according to actual needs or the impact of indicators in a specific environment.

[0050] After obtaining the assignment results of the three indicators of the pressure layer, according to the equal weight method or the weight method, the assignment results of the three indicators are weighted and then summed to obtain the assignment result of the pressure layer; similarly, the assignment results of the state layer and the response layer can be obtained;

[0051] After obtaining the assignment results of the pressure layer, state layer and response layer, the assignment results of the three layers are weighted again according to the equal weight method or the weight method, and then summed up to obtain the assignment results of the ecological health status; according to the comprehensive score range corresponding to the assignment results of the ecological health status, the ecological health status evaluation results of the study sea area are obtained.

[0052] Specifically, the corresponding range of the comprehensive score is:

[0053] Very healthy (4 < score ≤ 5); healthy (3 < score ≤ 4); sub-healthy (2 < score ≤ 3); unhealthy (1 < score ≤ 2); sick (0 < score ≤ 1).

[0054] Preferably, in S4, based on the ecological health status evaluation results of the research sea area obtained in S3, the frequency distribution method is used to derive the benchmark value, which specifically includes:

[0055] The seawater environmental quality data in the marine environmental data set of the research sea area were used to conduct a normal distribution test, and the data that conformed to the normal distribution were used to derive the benchmark value;

[0056] If it does not conform to the normal distribution, the data will be transformed after identifying abnormal and extreme values, and re-tested until the data conforms to the normal distribution; if the data still cannot pass the normal distribution test, the pressure-response method will be used to derive the benchmark value;

[0057] Conduct frequency distribution analysis on the data that conform to normal distribution after inspection. For sea areas with very healthy or healthy ecological health status, take the corresponding value of 50% point of the frequency distribution curve as the benchmark value;

[0058] For sea areas with sub-healthy ecological health status, the corresponding value of the lower 25% point of the frequency distribution curve is taken as the benchmark value;

[0059] For sea areas where the ecological health status is unhealthy or pathological, the corresponding value of the lower 5% points of the frequency distribution curve is taken as the benchmark value.

[0060] Specifically, if it does not conform to the normal distribution, the data is transformed after identifying abnormal and extreme values, and re-tested until the data conforms to the normal distribution; the data transformation method can be achieved through logarithmic transformation and other methods.

[0061] The derivation of benchmark values ​​is mainly carried out by using the pressure-response method combined with the frequency distribution method. That is, since the frequency distribution method is only applicable when the data passes the normal distribution test; therefore, the pressure response method is mainly used, and the frequency distribution method is used when it can be combined with data that are applicable to the frequency distribution method.

[0062] When calculating the average value in S5, there may be a benchmark value obtained by the frequency distribution method, or there may be no benchmark value obtained by the frequency distribution method; if there is a benchmark value obtained by the frequency distribution method, the average value of the two is calculated as the environmental benchmark recommended value;

[0063] If the data cannot be applied to the frequency distribution method, only the benchmark value of the pressure-response method will be obtained in the end. Then the benchmark value of the pressure-response method is the recommended environmental benchmark value.

[0064] Preferably, according to the pressure variable index and the response variable index obtained in S2, the baseline value is derived by the pressure-response method, and the pressure-response model is established by using a classification regression tree, which specifically includes:

[0065] S4.1,Tree construction,The tree is constructed using a binary recursive classification method of nodes, and each generated node is assigned a prediction class based on the distribution of training dataset classes appearing in the nodes and cost decision matrix;

[0066] S4.2. Stop building the tree. The tree generated at this stage contains overfitting information in the training data set. S4.3. Prune the tree. Generate a series of simpler trees by pruning the added important nodes. S4.4. Select the optimal tree. In a series of pruning processes, select the optimal tree model that removes overfitting. S4.5. Use the root node index concentration value of the optimal tree of the classification regression tree as the benchmark value.

[0067] A device for obtaining an environmental benchmark for a land-based pollution source entering the sea is used in a method for obtaining an environmental benchmark for a land-based pollution source entering the sea as described in any one of the above items.

[0068] Compared with the prior art, the present invention achieves the following beneficial effects:

[0069] 1. The present invention proposes a marine ecological health evaluation index system based on a pressure-state-response model, wherein the pressure layer includes population density, urban land use ratio and pollutant load per unit area, the state layer includes CODMn, TN, TP, phytoplankton diversity, zooplankton diversity and large benthic biodiversity indicators, and the response layer includes urban domestic sewage centralized collection rate, rural domestic sewage treatment rate, industrial wastewater discharge rate and protection zone grade indicators. The evaluation index system not only includes the water environment quality and ecological status of the sea area, but also introduces the discharge and treatment of land-based pollution sources entering the sea, and considers the ecological environmental pressure, pollution prevention and control and environmental protection measures of the land catchment area. Compared with the use of only seawater environmental quality and biodiversity indicators for ecological health evaluation, the marine ecological health evaluation index system proposed by the present invention can better reflect the impact of land-based pollution input on the sea area, and the assessment of the ecological health status of the sea area is more comprehensive, which can provide a better scientific basis for the sea area to control the main land-based pollutants entering the sea.

[0070] 2. The present invention proposes a method for identifying major land-based pollutants entering the sea using the equal-standard pollution load method. Compared with the traditional pollution load calculation method, the equal-standard pollution load method makes it possible to compare different pollution sources and different pollutants that are not convenient for quantitative comparison by standardizing different pollutants. It can comprehensively evaluate the potential pollution capacity of different pollutants or pollution sources to the environment, which helps to more accurately identify major land-based pollutants entering the sea.

[0071] 3. The present invention provides a method for assigning values ​​to various indicators in the marine ecological health evaluation index system, which is easy to operate and helps to better carry out the marine ecological health status evaluation.

[0072] 4. The present invention uses a combination of statistical analysis methods and pressure-response model methods to establish a baseline value derivation method for major land-based pollutants entering the sea, which can better reveal the complex interaction relationship between pressure variable indicators and response variable indicators, thereby determining the baseline value of pollutants. BRIEF DESCRIPTION OF THE DRAWINGS

[0073] Figure 1 It is a flow chart of a method for obtaining an environmental benchmark for land-based marine pollution sources provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0074] In order to make the purpose, technical solution and advantages of the present invention more clear, the technical solution in the embodiment of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiment of the present invention. Obviously, the described embodiment is only a part of the embodiment of the present invention, not all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0075] Example

[0076] like Figure 1 , a method for obtaining an environmental benchmark for land-based pollution sources entering the sea, comprising the following steps,

[0077] S1. Divide the land catchment area of ​​the research sea area, which includes plain areas, non-plain areas, and artificial diversion areas;

[0078] The watershed division in the plain area is to automatically extract and draw the watershed boundary through the ArcSWAT model; the operation steps include loading a digital elevation model without depressions (with an accuracy of not less than 30m), performing flow direction analysis, calculating the accumulated flow volume, setting a threshold, extracting a river network, specifying the total water outlet and dividing the sub-basin, and drawing the watershed boundary;

[0079] The watershed area of ​​the non-plain area is divided by manually extracting and drawing the boundaries of the watershed area; the operation steps include identifying ridges and valleys, extracting rivers and watersheds based on high-precision topographic maps (with an accuracy of no less than 1:100,000), extracting flat areas with reference to roads, administrative boundaries, etc., starting from the river mouth, along the watershed and then back to the river mouth, and outlining the boundaries of the watershed area;

[0080] The artificial diversion area is an area where the natural drainage direction is affected by sewage interception and diversion. The boundary of the catchment area is drawn, adjusted and corrected through the direction of the drainage network and artificial channels.

[0081] Collect environmental data of the catchment area to obtain a terrestrial environmental data set; collect seawater environmental data of the research sea area to obtain a marine environmental data set;

[0082] The marine environment data set includes seawater environment quality data and biodiversity data;

[0083] The survey collected seawater environmental quality data in the research area, including dissolved oxygen, permanganate index, ammonia nitrogen, nitrate, nitrite, total nitrogen, active phosphate, total phosphorus, active silicate, chlorophyll a and other indicators;

[0084] Biodiversity data include phytoplankton, zooplankton, and macrobenthic diversity;

[0085] The terrestrial environmental data set includes the pollution source discharge data into the sea in the catchment area and the pollution control data in the catchment area;

[0086] The data on pollution sources discharged into the sea in the catchment area include industrial sources, urban life sources, rural life sources, livestock and poultry breeding sources, aquaculture sources, and agricultural planting sources;

[0087] The pollution control data of the catchment area include the centralized collection rate of urban domestic sewage, the rural domestic sewage treatment rate, the industrial wastewater discharge rate that meets the standards, population, land use, establishment of nature reserves and other information.

[0088] S2. Evaluate the seawater quality in the research area, calculate the pollution index of different pollutants in the seawater by the standard index method and rank them, and obtain the seawater quality exceeding standard index; specifically include:

[0089] According to the seawater environmental quality data in the marine environment data set, the concentrations of different pollutants in seawater are obtained; the pollution index of different pollutants in seawater is obtained through the standard index calculation formula. The standard index calculation formula is as follows:

[0090]

[0091] Among them, P i is the pollution index of pollutant i in seawater. When the pollution index > 1, it means that the standard is exceeded; C i is the concentration of pollutant i in seawater, in mg / L; S i is the environmental quality standard of pollutant i in seawater, in mg / L;

[0092] P i The values ​​are arranged from large to small, and the pollutants corresponding to the top three pollution indices are selected as the main indicators of seawater quality exceeding the standard.

[0093] The pollution discharge load of land-based pollutants entering the sea is calculated, and the equivalent pollution load of major land-based pollutants entering the sea is calculated and ranked by the equivalent pollution load method to obtain the indicators of land-based pollutants entering the sea; specifically, it includes:

[0094] According to the emission data of pollution sources in the catchment area into the sea in the terrestrial environmental data set, the absolute emission of different pollutants is obtained; the equivalent pollution load of different pollutants is obtained through the equivalent pollution load calculation formula. The calculation formula of the equivalent pollution load is as follows:

[0095]

[0096] Among them, L j is the equivalent pollution load of pollutant j in any pollution source entering the sea in the catchment area, q j is the absolute emission of pollutant j, in tons / year, C ojis the evaluation standard of pollutant j, the unit is mg / L, L n is the equivalent pollution load of all pollution sources entering the sea in the catchment area, and n is the number of pollution sources entering the sea in the catchment area;

[0097] L j The values ​​are arranged from large to small, and the pollutants corresponding to the top three equal-standard pollution loads are selected as the main indicators of land-based pollutants entering the sea.

[0098] There are many pollution sources in the catchment area, such as industrial sources, urban living sources, etc. Each pollution source contains a variety of pollutants. n The design and calculation are to facilitate a better understanding of the environmental conditions of the catchment area.

[0099] The union of the obtained seawater quality exceeding standard index and the land-based pollutant inflow index is used as the pressure variable index for calculating the environmental benchmark of land-based pollutants inflow into the sea, and dissolved oxygen and chlorophyll a are used as response variable indexes;

[0100] S3. Based on the pressure variable index and the response variable index, a pressure-state-response model is constructed. Based on the pressure-state-response model, an evaluation index system for marine ecological health is established. The ecological health status of the research sea area is evaluated to obtain the evaluation results of the ecological health status of the research sea area.

[0101] The marine ecological health assessment index system includes a pressure layer, a state layer, and a response layer;

[0102] The pressure layer includes population density, proportion of urban land and pollutant load per unit area; the state layer includes CODMn, TN, TP, phytoplankton diversity, zooplankton diversity and large benthic biodiversity indicators; the response layer includes urban domestic sewage centralized collection rate, rural domestic sewage treatment rate, industrial wastewater discharge rate and protected area grade indicators.

[0103] According to the various indicators contained in the pressure layer, state layer, and response layer, each indicator is divided into intervals and assigned values; according to the corresponding values ​​of the intervals where the indicators are located, the assignment results are obtained, and then the weighted method or equal weighted method is used to calculate the comprehensive scores of the assignment results of each indicator. According to the comprehensive scores, the ecological health status evaluation results of the research sea area are evaluated and obtained;

[0104] The ecological health status evaluation results include very healthy, healthy, sub-healthy, unhealthy, and pathological.

[0105] The result of the assignment is the value assigned to the interval in which the actual value of a certain indicator is located;

[0106] The weighting method is to give weight calculation to the corresponding value results of the indicators, and different weights can be given according to the degree of impact of different indicators on the environment;

[0107] The equal weight method is to give the same weight to the assignment results corresponding to all indicators for calculation, that is, to find the average, and give the same weight to different indicators;

[0108] The weighted method or equal-weighted method can set reasonable weights according to actual needs or the impact of indicators in a specific environment.

[0109] After obtaining the assignment results of the three indicators of the pressure layer, according to the equal weight method or the weight method, the assignment results of the three indicators are weighted and then summed to obtain the assignment result of the pressure layer; similarly, the assignment results of the state layer and the response layer can be obtained;

[0110] After obtaining the assignment results of the pressure layer, state layer and response layer, the assignment results of the three layers are weighted again according to the equal weight method or the weight method, and then summed up to obtain the assignment results of the ecological health status; according to the comprehensive score range corresponding to the assignment results of the ecological health status, the ecological health status evaluation results of the study sea area are obtained.

[0111] The corresponding range of the comprehensive score is: very healthy (4 < score ≤ 5); healthy (3 < score ≤ 4); sub-healthy (2 < score ≤ 3); unhealthy (1 < score ≤ 2); pathological (0 < score ≤ 1).

[0112] The marine ecological health assessment index system is shown in the following table:

[0113]

[0114] Taking the population density index in the pressure layer as an example, the population density of the land catchment area is first divided into intervals, which can be specifically divided into population density [0,400); [400,600); [600,800); [800,1000);

[0115] [1000,+∞); Unit: person / km 2 ;

[0116] Assign values ​​to the five divided intervals: [0,400), assign 5; [400,600), assign 4;

[0117] [600,800), assigned a value of 3; [800,1000), assigned a value of 2; [1000,+∞), assigned a value of 1; that is, the higher the population density, the greater the impact on the environment, and the lower the value;

[0118] According to the actual population situation of the land catchment area of ​​the study sea area, the corresponding value of population density is obtained; for example, if the population density is 700 people km2 ; The corresponding assignment result is 3;

[0119] Similarly, the assignment results of the urban land proportion index and the unit area pollutant load in the pressure layer can be obtained; for example, the assignment result of the urban land proportion index is 4, and the assignment result of the unit area pollutant load is 5; thus, the assignment results of the three indicators of the pressure layer are 3, 4, and 5 respectively; then the equal weight method is adopted, that is, the weights of the three indicators are the same, all 1 / 3; after multiplying the assignment results of the three indicators by the weight 1 / 3 respectively, the added value is the assignment result of the pressure layer; that is, 1 / 3*3+1 / 3*4+1 / 3*5=4; that is, the assignment result of the pressure layer is 4;

[0120] This method can also be used to obtain the assignment results of the six indicators of the state layer. According to the equal weight method, the weight of each indicator is 1 / 6. The assignment result of the state layer can be obtained by calculation. If the assignment result of the state layer is 3;

[0121] Similarly, the assignment result of the response layer can be obtained. If the assignment result of the response layer is 2; then according to the assignment result of the pressure layer 4, the assignment result of the state layer is 3, and the assignment result of the response layer is 2, the equal weight method is used, that is, the weights of the three layers are 1 / 3, multiplied by the weights and then summed up, the assignment result is 3, the corresponding range of the comprehensive score, 3 points corresponds to sub-health (2 < score ≤ 3); then the final ecological health status evaluation result of the study sea area can be obtained as sub-health.

[0122] It is also possible to adopt a weighting method according to the actual environmental conditions, assign different weight ratios to different assignment results and then sum them up to obtain assignment results with different indicator weights.

[0123] S4. Based on the pressure variable index, response variable index and ecological health status of the study sea area, the frequency distribution method and pressure-response method are used to derive the baseline value for the study sea area;

[0124] First, based on the ecological health status evaluation results of the research area obtained by S3, the frequency distribution method was used to derive the benchmark value, including:

[0125] The seawater environmental quality data in the marine environmental data set of the research sea area were used to conduct a normal distribution test, and the data that conformed to the normal distribution were used to derive the benchmark value;

[0126] If it does not conform to the normal distribution, the data will be transformed after identifying abnormal and extreme values, and re-tested until the data conforms to the normal distribution; if the data still cannot pass the normal distribution test, the pressure-response method will be used to derive the benchmark value;

[0127] Conduct frequency distribution analysis on the data that conform to normal distribution after inspection. For sea areas with very healthy or healthy ecological health status, take the corresponding value of 50% point of the frequency distribution curve as the benchmark value;

[0128] For sea areas with sub-healthy ecological health status, the corresponding value of the lower 25% point of the frequency distribution curve is taken as the benchmark value;

[0129] For sea areas where the ecological health status is unhealthy or pathological, the corresponding value of the lower 5% points of the frequency distribution curve is taken as the benchmark value.

[0130] Secondly, according to the pressure variable index and response variable index obtained by S2, the baseline value is derived through the pressure-response method, and the pressure-response model is established using the classification regression tree, which includes:

[0131] S4.1,Tree construction,The tree is constructed using a binary recursive classification method of nodes, and each generated node is assigned a prediction class based on the distribution of training dataset classes appearing in the nodes and cost decision matrix;

[0132] S4.2. Stop building the tree. The "largest" tree generated at this stage may contain overfitting information in the training data set.

[0133] S4.3, tree pruning, generating a series of increasingly simple trees by pruning increasingly important nodes;

[0134] S4.4, optimal tree selection, in a series of branch reduction processes, the optimal tree model that fits the training data set information but does not overfit is selected;

[0135] S4.5. The root node index concentration value of the optimal classification and regression tree is used as the benchmark value.

[0136] The classification regression tree model is established using R language. The code example is as follows:

[0137] # Load the package

[0138] library(rpart)

[0139] library(rpart.plot)

[0140] library(readxl)

[0141] library(tidyverse)

[0142] library(caret)

[0143] # Load data

[0144] cartdata<-read_excel("Classification and regression tree analysis data.xlsx")

[0145] # Distribution of dependent variables

[0146] hist(cartdata$response variable 1, breaks=50)

[0147] hist(log(cartdata$response variable 1),breaks=50)

[0148] ##########################

[0149] #Train model

[0150] set.seed(1025)

[0151] dtree<-rpart(

[0152] Response variable 1 ~ pressure variable 1 + pressure variable 2,

[0153] data = cartdata,

[0154] method = "anova",

[0155] control=rpart.control(cp=0.005,minbucket=10))

[0156] #Regression Tree

[0157] dtree

[0158] Complexity related data

[0159] #printcp(dtree)

[0160] #plotcp(dtree)

[0161] #

[0162] ##cp corresponding to the minimum rule

[0163] #dtree$cptable

[0164] #cpMin<-

[0165] #dtree$cptable[which.min(dtree$cptable[,4]),1]#cpMin

[0166] #

[0167] ##cp corresponding to one standard deviation rule

[0168] #thres1SE<-sum(dtree$cptable[

[0169] #which.min(dtree$cptable[,4]),4:5])

[0170] #cp1SE<-dtree$cptable[

[0171] #min(which(dtree$cptable[,4]<=thres1SE)),1]

[0172] #cp1SE

[0173] #

[0174] ##Post-pruning (one standard deviation rule)

[0175] #dtree_pruned<-prune(dtree,cp=cp1SE)

[0176] #print(dtree_pruned)

[0177] #summary(dtree_pruned)

[0178] #Treemap

[0179] prp(dtree,

[0180] type=1,

[0181] extra=101,

[0182] fallen.leaves=TRUE,

[0183] main="Decision Tree")

[0184] #Box plot

[0185] cartdata2<-cartdata

[0186] cartdata2$leaf node number <- dtree$wherecartdata2 grouping <- cartdata2 %> %

[0187] group_by(leaf node number) %>%

[0188] summarise(response variable 1 mean = mean(response variable 1)) %>%

[0189] arrange(response variable 1 mean) %>%

[0190] mutate(group=paste0("group",1:length(unique(dtree$where))))cartdata2%>%

[0191] left_join(cartdata2 grouping) %>%

[0192] ggplot(aes(x=group,y=response variable1))+

[0193] geom_boxplot()+

[0194] theme_bw()

[0195] #####################

[0196] #Prediction results

[0197] prepy<-predict(dtree,newdata=cartdata)

[0198] #Prediction error indicator

[0199] defaultSummary(data.frame(obs=cartdata$response variable1,pred=predy))

[0200] #Graphical prediction results

[0201] plot(x=cartdata$response variable1,

[0202] y=predy,

[0203] xlab="Actual",

[0204] ylab="Prediction",

[0205] main="Comparison of actual value and predicted value")

[0206] abline(a=0,b=1,col="red",lwd=2.5,lty="dashed")

[0207] The present invention provides an R language code example for implementing a classification regression tree model in a pressure-response model method, which is helpful for deriving benchmark values ​​of major land-based pollutants entering the sea.

[0208] S5. The average value of the baseline data obtained in S4 is used as the recommended environmental baseline value for land-based pollutants entering the sea.

[0209] The derivation of benchmark values ​​is mainly carried out by using the pressure-response method combined with the frequency distribution method. That is, since the frequency distribution method is only applicable when the data passes the normal distribution test; therefore, the pressure response method is mainly used, and the frequency distribution method is used when it can be combined with data that are applicable to the frequency distribution method.

[0210] When calculating the average value in S5, there may be a benchmark value obtained by the frequency distribution method, or there may be no benchmark value obtained by the frequency distribution method; if there is a benchmark value obtained by the frequency distribution method, the average value of the two is calculated as the environmental benchmark recommended value;

[0211] If the data cannot be applied to the frequency distribution method, only the benchmark value of the pressure-response method will be obtained in the end. Then the benchmark value of the pressure-response method is the recommended environmental benchmark value.

[0212] This embodiment also provides a device for obtaining an environmental benchmark for land-based pollution sources entering the sea, which is applied to the method for obtaining an environmental benchmark for land-based pollution sources entering the sea as described above.

[0213] According to the disclosure and teaching of the above description, those skilled in the art to which the present invention belongs may also make changes and modifications to the above embodiments. Therefore, the present invention is not limited to the specific embodiments disclosed and described above, and some modifications and changes to the present invention should also fall within the scope of protection of the claims of the present invention. In addition, although some specific terms are used in this specification, these terms are only for the convenience of description and do not constitute any limitation to the present invention.

Claims

1. A method for obtaining environmental benchmarks for land-based pollution sources entering the sea, characterized in that: The following steps are involved: S1. Divide the land catchment area of ​​the research sea area, which includes plain areas, non-plain areas, and artificial diversion areas; Collect environmental data of the catchment area to obtain a terrestrial environmental data set; collect seawater environmental data of the research sea area to obtain a marine environmental data set; The marine environment data set includes seawater environment quality data and biodiversity data; The terrestrial environmental data set includes the pollution source discharge data into the sea in the catchment area and the pollution control data in the catchment area; S2. Evaluate the seawater quality in the research area, calculate the pollution index of different pollutants in the seawater by the standard index method and rank them, and obtain the seawater quality exceeding standard index; The pollution discharge load of land-based pollutants entering the sea is calculated, and the equivalent pollution load of land-based pollutants entering the sea is calculated and ranked by the equivalent pollution load method to obtain the indicators of land-based pollutants entering the sea; specifically, it includes: According to the emission data of pollution sources in the catchment area into the sea in the terrestrial environmental data set, the absolute emission of different pollutants is obtained; the equivalent pollution load of different pollutants is obtained through the equivalent pollution load calculation formula. The calculation formula of the equivalent pollution load is as follows: Among them, L j is the equivalent pollution load of pollutant j in any pollution source entering the sea in the catchment area, q j is the absolute emission of pollutant j, in tons / year, C oj is the evaluation standard of pollutant j, the unit is mg / L, L n is the equivalent pollution load of all pollution sources entering the sea in the catchment area, and n is the number of pollution sources entering the sea in the catchment area; L j The values ​​are arranged from large to small, and the pollutants corresponding to the equivalent pollution loads of the top three pollutants are selected as indicators of land-based pollutants entering the sea; The union of the obtained seawater quality exceeding standard index and the land-based pollutant inflow index is used as the pressure variable index for calculating the environmental benchmark of land-based pollutants inflow into the sea, and dissolved oxygen and chlorophyll a are used as response variable indexes; S3. Construct a pressure-state-response model, evaluate the ecological health status of the study sea area through the pressure-state-response model, and obtain the evaluation results of the ecological health status of the study sea area; specifically include: Based on the pressure-state-response model, an evaluation index system for marine ecological health is established, and the ecological health status of the research sea area is evaluated through the evaluation index system for marine ecological health. The marine ecological health assessment index system includes a pressure layer, a state layer, and a response layer; According to the various indicators contained in the pressure layer, state layer, and response layer, each indicator is divided into intervals and assigned values. According to the corresponding values ​​of the intervals where the indicators are located, the assignment results are obtained, and then the weight method or equal weight method is used to calculate the comprehensive scores of the assignment results of each indicator. According to the comprehensive scores, the ecological health status evaluation results of the research sea area are evaluated and obtained. The specific methods are as follows: After obtaining the assignment results of the pressure layer, state layer and response layer, the assignment results of the three layers are weighted and summed according to the equal weight method or weight method to obtain the assignment result of the ecological health status; according to the comprehensive score range corresponding to the assignment result of the ecological health status, the ecological health status evaluation result of the research sea area is obtained; The ecological health status evaluation results include very healthy, healthy, sub-healthy, unhealthy, and pathological; S4. Based on the ecological health status assessment results, pressure variable indicators and response variable indicators of the study sea area, the frequency distribution method and pressure-response method are used to derive the baseline value for the study sea area; S5. The average value of the baseline data obtained in S4 is used as the recommended environmental baseline value for land-based pollutants entering the sea.

2. The method for obtaining environmental benchmarks for land-based pollution sources entering the sea according to claim 1, characterized in that: The watershed area of ​​the plain area is divided by automatically extracting and drawing the watershed area boundary through the ArcSWAT model; The demarcation of the watershed in the non-plain area is done by manually extracting and drawing the boundaries of the watershed; The artificial diversion area is an area where the natural drainage direction is affected by sewage interception and diversion. The boundary of the catchment area is drawn and corrected through the direction of the drainage network and artificial channels.

3. The method for obtaining environmental benchmarks for land-based pollution sources entering the sea according to claim 1, characterized in that: In S2, the seawater quality of the research sea area is evaluated, and the pollution index of different pollutants in the seawater is calculated by the standard index method; specifically, it includes: According to the seawater environmental quality data in the marine environment data set, the concentrations of different pollutants in seawater are obtained; the pollution index of different pollutants in seawater is obtained through the standard index calculation formula. The standard index calculation formula is as follows: Among them, P i is the pollution index of pollutant i in seawater. When the pollution index is > 1, it means that the standard is exceeded. i The values ​​are arranged from large to small, and the pollutants corresponding to the top three pollution indices are selected as the indicators of seawater quality exceeding the standard; C i is the concentration of pollutant i in seawater, in mg / L; S i It is the environmental quality standard of pollutant i in seawater, and the unit is mg / L.

4. The method for obtaining environmental benchmarks for land-based pollution sources entering the sea according to claim 1, characterized in that: In S4, based on the ecological health status evaluation results of the research sea area obtained in S3, the frequency distribution method is used to derive the benchmark value, which specifically includes: The seawater environmental quality data in the marine environmental data set of the research sea area were used to conduct a normal distribution test, and the data that conformed to the normal distribution were used to derive the benchmark value; If it does not conform to the normal distribution, the data will be transformed after identifying abnormal and extreme values, and re-tested until the data conforms to the normal distribution; if the data still cannot pass the normal distribution test, the pressure-response method will be used to derive the benchmark value; Conduct frequency distribution analysis on the data that conform to normal distribution after inspection. For sea areas with very healthy or healthy ecological health status, take the corresponding value of 50% point of the frequency distribution curve as the benchmark value; For sea areas with sub-healthy ecological health status, the corresponding value of the lower 25% point of the frequency distribution curve is taken as the benchmark value; For sea areas where the ecological health status is unhealthy or pathological, the corresponding value of the lower 5% points of the frequency distribution curve is taken as the benchmark value.

5. A method for obtaining environmental benchmarks for land-based pollution sources entering the sea according to claim 4, characterized in that: In S4, based on the pressure variable index and the response variable index obtained in S2, the baseline value is derived by the pressure-response method, and the pressure-response model is established by using a classification regression tree, which specifically includes: S4.1,Tree construction,The tree is constructed using a binary recursive classification method of nodes, and each generated node is assigned a prediction class based on the distribution of training dataset classes appearing in the nodes and cost decision matrix; S4.2, stop building the tree. The tree generated at this stage contains overfitting information in the training data set; S4.3, tree pruning, generating a series of increasingly simple trees by pruning increasingly important nodes; S4.4, optimal tree selection, select the optimal tree model that removes overfitting in a series of branch reduction processes; S4.

5. The root node index concentration value of the optimal classification and regression tree is used as the benchmark value.

6. A device for obtaining environmental benchmarks for land-based pollution sources entering the sea, characterized in that: The method is applied in a method for obtaining an environmental benchmark for land-based marine pollution sources as described in any one of claims 1 to 5.

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