Site compound contaminated soil ecological risk assessment method

Abstract

The present application relates to the technical field of soil ecological risk assessment, in particular to a kind of site composite contaminated soil ecological risk assessment method, including risk rapid identification stage, first stage preliminary assessment, second stage detailed assessment and third stage composite pollution risk characterization, based on the ecological receptor of different land types, exposure route, toxicity end point and protection level derivation screening value, compare and obtain the pollutant concentration of investigation with screening value, and based on pollutant concentration and form investigation, pollutant bioavailability investigation test, pollutant biological toxicity test and ecological investigation, using quotient method, index method (evidence weight method), probability method assesses site soil pollution ecological risk, and the ecological risk of composite contaminated soil is characterized, compared with prior art, the ecological risk of site composite contaminated soil can be reasonably evaluated, and the safety of ecological environment is guaranteed.

Description

Technical Field

[0001] This invention relates to the field of soil ecological risk assessment technology, specifically a method for assessing the ecological risk of soil with complex site pollution. Background Technology

[0002] In recent years, with the accelerated pace of industrial upgrading and rapid urbanization in my country, much land in cities has been repurposed as part of this urbanization process, such as becoming new industrial land, residential land, or parkland.

[0003] Currently, the main focus is on the impact of soil pollution on human health. The impact of soil pollution on ecological receptors such as soil animals, microorganisms, and plants, as well as their service functions, has not received sufficient attention, and there is no systematic method to assess the ecological risk of soils with complex pollution at a site.

[0004] Therefore, it is necessary to design an ecological risk assessment method for soils with complex contamination at a site. Based on different land types, the ecological risk of the corresponding contaminated soil can be obtained through multiple assessment steps and risk assessment methods, thus providing a guarantee for ecological security during urban development. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for ecological risk assessment of soil with complex pollution in a site. Based on different land types, through multiple assessment steps and risk assessment methods, the ecological risk of the corresponding polluted soil can be obtained, thus providing a guarantee for ecological security in the process of urban development.

[0006] To achieve the above objectives, the present invention provides a method for ecological risk assessment of soil with complex contamination at a site, comprising the following steps:

[0007] S1: Rapid Risk Identification Phase;

[0008] S2: Initial assessment of the first phase;

[0009] S3: Second Phase Detailed Assessment;

[0010] S4: Third-stage composite pollution risk characterization;

[0011] S1 is based on the rapid observation, measurement, and testing of pollutant concentrations and other physical, chemical, and biological indicators in the soil or organisms of the assessment and control areas to preliminarily identify whether there are potential risks, to preliminarily determine areas that may be at risk, and to identify receptors that may be affected.

[0012] S2 is to take the lower of the screening values ​​derived from the direct exposure pathway and the screening values ​​derived from the uptake pathway as the final screening value. The soil pollutant concentrations obtained from the survey are compared with the derived soil pollution ecological risk screening values ​​to determine whether the risk is acceptable. If it is acceptable, the assessment is terminated; if it is not acceptable, the second stage of detailed assessment is entered.

[0013] S3 is based on pollutant concentration and speciation surveys, pollutant bioavailability surveys and tests, pollutant biotoxicity tests and ecological surveys, and uses the quotient method, index method (weight of evidence method) and probability method to assess site soil pollution risk.

[0014] S4 involves conducting a study on the toxic effects of combined pollution. It uses either a concentration summation or effect summation method to comprehensively characterize the risk values ​​of different pollutants obtained in the second stage. First, the concentration of residual pollutants in the tissue is obtained and compared with toxicity reference values. If the ratio is less than 1, the risk of different pollutants is characterized using a concentration summation method, i.e., the following formula is used:

[0015]

[0016] If the ratio of tissue residual concentration to toxicity reference value is >1, it is classified into different toxicity mechanisms of MeOA. The internal toxicity unit ITUmix for each MeOA is calculated using CA, as follows:

[0017]

[0018]

[0019] If ITUmix is ​​less than the threshold, it is characterized using the CA formula:

[0020]

[0021] For values ​​greater than or equal to the threshold, the summation of effects (IA) is used for characterization, as shown in the formula:

[0022]

[0023] In the formula, HQi represents the ecological risk of a single pollutant, PAFi represents the proportion of damaged biological species by a single pollutant, ITUi is the internal toxicity unit, ICI is the liquid phase concentration of i in the mixture, and IECpi is the effective concentration of i.

[0024] The screening values ​​derived from S2 need to be selected based on different land use types to select appropriate ecological receptors, exposure pathways, toxic endpoints, and protection levels.

[0025] Land use types include industrial land, residential land, park green space, and mines. The ecological receptors for industrial land are microorganisms and soil animals, the exposure pathway is direct exposure, and the protection level is set at 50%. The ecological receptors for residential land are microorganisms, soil animals, and plants, the exposure pathway is direct exposure, and the protection level is set at 60%. The ecological receptors for park green space are microorganisms, soil animals, plants, and birds, the exposure pathways are direct exposure and ingestion, and the protection level is set at 80%. The ecological receptors for mines are microorganisms, soil animals, plants, and higher animals, the exposure pathways are direct exposure and ingestion, and the protection level is set at 80%.

[0026] The principle for selecting toxicity endpoints is: EC10>EC20>EC25>EC30>EC50>NOEC. EC represents the toxicity effect data of pollutants, which is mainly used to construct SSD curves. The 5th percentile on the curve is selected as the screening value.

[0027] The quotient method is based on information obtained in the detailed assessment phase. The screening values ​​obtained in the first phase are corrected, and the pollutant concentration is compared with the corrected screening values ​​to obtain a risk quotient based on soil pollution concentration. Alternatively, based on information obtained in the detailed investigation and assessment phase, the biological exposure is calculated, and a toxicity reference value is derived. The biological exposure is compared with the toxicity reference value to obtain a risk quotient based on biological exposure.

[0028] The index method (weighted evidence method) considers indicators related to soil pollution risk, constructs a comprehensive assessment index, and calculates a comprehensive risk index.

[0029] The probabilistic approach to risk assessment mainly involves superimposing the probability distributions of pollutant concentrations and toxicity data to obtain probabilistic risk.

[0030] The quotient method, the index method (weight of evidence method), and the probability method can all be used for industrial land, residential land, park green space, and mines.

[0031] Compared with existing technologies, this invention derives screening values ​​based on ecological receptors, exposure pathways, toxic endpoints, and protection levels for different land types. The screening values ​​are then compared with pollutants obtained from surveys. Based on pollutant concentration and speciation surveys, pollutant bioavailability surveys and tests, pollutant biotoxicity tests, and ecological surveys, the invention employs the quotient method, index method (weight of evidence method), and probability method to assess the ecological risk of site soil pollution. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the evaluation process of the present invention.

[0033] Figure 2 This is a schematic diagram of a non-ferrous metal mining and processing site according to the present invention.

[0034] Figure 3 This is a schematic diagram of soil pollutant concentration data according to the present invention.

[0035] Figure 4 This is a schematic diagram of existing soil pollution ecological risk screening values ​​in developed countries.

[0036] Figure 5 This is a schematic diagram of pollutant toxicity data from various countries, as presented in this invention.

[0037] Figure 6 This is an SSD curve of arsenic according to the present invention.

[0038] Figure 7 This is an SSD curve of lead according to the present invention.

[0039] Figure 8 This is a schematic diagram illustrating the situation where the concentration of soil pollutants at the site exceeds the ecological screening value according to the present invention.

[0040] Figure 9 This is a schematic diagram of pollutant concentration data and its logarithm according to the present invention.

[0041] Figure 10 This is a schematic diagram of the pollutant toxicity data and its logarithm according to the present invention.

[0042] Figure 11 This is a schematic diagram of the probability curve corresponding to the arsenic concentration of the present invention (i.e., 5% of species are affected).

[0043] Figure 12 This is a schematic diagram of the probability curve corresponding to the arsenic concentration of the present invention (i.e., 1% of species are affected).

[0044] Figure 13 This is a schematic diagram of the probability curve corresponding to the lead concentration of the present invention (i.e., 5% of species are affected).

[0045] Figure 14 This is a schematic diagram of the probability curve corresponding to the lead concentration of the present invention (i.e., 1% of species are affected). Detailed Implementation

[0046] The present invention will now be further described with reference to the accompanying drawings.

[0047] See Figure 1 This invention provides a method for ecological risk assessment of soil with complex pollution at a site, comprising the following steps:

[0048] S1: Rapid Risk Identification Phase;

[0049] S2: Initial assessment of the first phase;

[0050] S3: Second Phase Detailed Assessment;

[0051] S4: Third-stage composite pollution risk characterization;

[0052] S1 is based on the rapid observation, measurement, and testing of pollutant concentrations and other physical, chemical, and biological indicators in the soil or organisms of the assessment and control areas to preliminarily identify whether there are potential risks, to preliminarily determine areas that may be at risk, and to identify receptors that may be affected.

[0053] S2 is the lower of the screening values ​​derived from direct exposure and ingestion pathways, which is taken as the final screening value. The soil pollutant concentrations obtained from the survey are compared with the derived soil pollution ecological risk screening values ​​to determine whether the risk is acceptable. If it is acceptable, the assessment is terminated; if it is not acceptable, the second stage of detailed assessment is entered.

[0054] S3 is based on pollutant concentration and speciation surveys, pollutant bioavailability surveys and tests, pollutant biotoxicity tests and ecological surveys, and uses the quotient method, index method (weight of evidence method) and probability method to assess site soil pollution risk.

[0055] S4 involves conducting a study on the toxic effects of combined pollution. It uses either a concentration summation or effect summation method to comprehensively characterize the risk values ​​of different pollutants obtained in the second stage. First, the concentration of residual pollutants in the tissue is obtained and compared with toxicity reference values. If the ratio is less than 1, the risk of different pollutants is characterized using a concentration summation method, i.e., the following formula is used:

[0056]

[0057] If the ratio of tissue residual concentration to toxicity reference value is >1, it is classified into different toxicity mechanisms of MeOA. The internal toxicity unit ITUmix for each MeOA is calculated using CA, as follows:

[0058]

[0059]

[0060] If ITUmix is ​​less than the threshold, it is characterized using the CA formula:

[0061]

[0062] For values ​​greater than or equal to the threshold, the summation of effects (IA) is used for characterization, as shown in the formula:

[0063]

[0064] In the formula, HQi represents the ecological risk of a single pollutant, PAFi represents the proportion of damaged biological species by a single pollutant, ITUi is the internal toxicity unit, ICI is the liquid phase concentration of i in the mixture, and IECpi is the effective concentration of i.

[0065] The screening values ​​derived from S2 need to be selected based on different land use types to identify appropriate ecological receptors, exposure pathways, toxicity priorities, and protection levels.

[0066] Land use types include industrial land, residential land, park green space, and mines. The ecological receptors for industrial land are microorganisms and soil animals, the exposure pathway is direct exposure, and the protection level is set at 50%. The ecological receptors for residential land are microorganisms, soil animals, and plants, the exposure pathway is direct exposure, and the protection level is set at 60%. The ecological receptors for park green space are microorganisms, soil animals, plants, and birds, the exposure pathways are direct exposure and ingestion, and the protection level is set at 80%. The ecological receptors for mines are microorganisms, soil animals, plants, and higher animals, the exposure pathways are direct exposure and ingestion, and the protection level is set at 80%.

[0067] The principle for selecting the toxicity priority is: EC10>EC20>EC25>EC30>EC50>NOEC, where EC represents the toxicity effect data of the pollutant, used to construct the SSD curve, and the 5th percentile on the curve is selected as the screening value.

[0068] The quotient method is based on information obtained in the detailed assessment phase. The screening values ​​obtained in the first phase are corrected, and the pollutant concentration is compared with the corrected screening values ​​to obtain a risk quotient based on soil pollution concentration. Alternatively, based on information obtained in the detailed investigation and assessment phase, the biological exposure is calculated, and a toxicity reference value is derived. The biological exposure is compared with the toxicity reference value to obtain a risk quotient based on biological exposure.

[0069] The index method (weighted evidence method) considers indicators related to soil pollution risk, constructs a comprehensive assessment index, and calculates a comprehensive risk index.

[0070] The probabilistic approach to risk assessment mainly involves superimposing the probability distributions of pollutant concentrations and toxicity data to obtain probabilistic risk.

[0071] The quotient method, the index method (weight of evidence method), and the probability method can all be used for industrial land, residential land, park green space, and mines.

[0072] Example:

[0073] Drawing on the soil pollution ecological risk assessment methods of developed countries, and combining them with the current status, characteristics and needs of contaminated sites in my country, we have constructed a method for ecological risk assessment of complex contaminated soil in contaminated sites in my country.

[0074] The method consists of four stages: rapid risk identification, preliminary assessment in the first stage, detailed assessment in the second stage, and complex pollution risk characterization in the third stage.

[0075] The rapid risk identification phase is mainly based on the rapid observation, measurement, and testing of pollutant concentrations and other physical, chemical, and biological indicators in the soil or organisms of the assessment and control areas. This phase aims to preliminarily identify whether there are potential risks, make preliminary judgments about areas that may be at risk, and identify receptors that may be affected.

[0076] The first phase of the preliminary assessment primarily relies on existing or derived ecological risk screening values ​​for soil pollution. The surveyed soil pollutant concentrations are compared with these screening values ​​to determine the acceptable level of risk. The derivation of these screening values ​​requires selecting appropriate ecological receptors, exposure pathways, toxic endpoints, and protection levels based on different land use types. In my country, contaminated sites from key industries such as metal smelting and petrochemicals are mainly converted into industrial land, residential land, and parks / green spaces. For industrial land, the primary ecological receptors are microorganisms and soil animals, with direct exposure as the main pathway, and a protection level of 50% is set. For residential land, the primary ecological receptors are microorganisms, soil animals, and plants, with direct exposure as the main pathway, and a protection level of 60% is set. For parks / green spaces, the primary ecological receptors are microorganisms, soil animals, plants, and birds, with direct exposure and ingestion as the main pathways, and a protection level of 80% is set. For mines, the primary ecological receptors are microorganisms, soil animals, plants, and higher animals, with direct exposure and ingestion as the main pathways, and a protection level of 80% is set. The selection principle for toxicity endpoints is EC10 > EC20 > EC25 > EC30 > EC50. The lower of the screening values ​​derived from direct exposure and ingestion pathways is used as the final screening value. The soil pollutant concentrations obtained from the survey are compared with the derived soil pollution ecological risk screening values ​​to determine whether the risk is acceptable. If acceptable, the assessment is terminated; if unacceptable, the detailed assessment phase begins.

[0077] The second phase of detailed assessment primarily relies on pollutant concentration and speciation surveys, bioavailability testing, biotoxicity testing, and ecological surveys. Methods such as the quotient method, index method (weighted evidence method), and probability method are used to assess the ecological risk of soil pollution at the site. These methods can be applied to industrial land, residential land, parks and green spaces, and mines. The quotient method, based on information obtained in the detailed assessment phase, modifies the screening values ​​obtained in the first phase, comparing the pollutant concentration with the modified screening values ​​to obtain a risk quotient based on soil pollution concentration. Alternatively, based on information obtained in the detailed investigation and assessment phase, it calculates biological exposure and derives toxicity reference values, comparing the biological exposure with the toxicity reference values ​​to obtain a risk quotient based on biological exposure. The index method (weighted evidence method) considers indicators related to soil pollution risk, constructs a comprehensive assessment index, and calculates a comprehensive risk index. The probability method assesses risk by superimposing the probability distributions of pollutant concentration and toxicity data to obtain probabilistic risk.

[0078] The third stage of risk characterization of compound pollution mainly involves conducting research on the toxic effects of compound pollution and selecting methods such as concentration summation or effect summation to comprehensively characterize the risk values ​​of different pollutants obtained in the second stage.

[0079] We will now select typical sites to validate the method for ecological risk assessment of soils with complex contamination:

[0080] The project research team collected 13 soil samples from a non-ferrous metal mining and processing site (see...). Figure 2 The concentration of heavy metals in the sample was analyzed (see results). Figure 3 According to the "Screening Values ​​and Control Values ​​for Soil Pollution Risk of Construction Land" (DB4403 / T67-2020), the concentrations of heavy metals such as arsenic, lead, nickel, and antimony in the soil exceeded the screening values ​​for Class II land use, indicating typical heavy metal-heavy metal complex pollution. Therefore, arsenic and lead were selected as representative indicators, and multiple methods were used to assess the ecological risk of soil pollution at this site.

[0081] Preliminary assessment phase:

[0082] Through a survey of existing soil pollution ecological risk screening values ​​in developed countries (see...) Figure 4 The study found that the minimum ecological risk screening value for As was 12 mg / kg and that for Pb was 11 mg / kg. Comparison of the collected soil pollutant concentrations with the screening values ​​showed that the pollutant concentrations at all locations exceeded the minimum ecological risk screening values, indicating that the site may have a high ecological risk due to As and Pb pollution.

[0083] A preliminary evaluation is conducted based on the derived screening values:

[0084] The first step in applying the entropy method for assessment is to derive the ecological screening values ​​for arsenic, lead, and nickel. Deriving soil screening values ​​based on the Species Sensitivity Distribution (SSD) is currently the most commonly used method. This method describes the probability distribution function of the differences in the toxic response effects of a limited number of species within an ecosystem to a specific pollutant in the environment. This method assumes that species are randomly selected from the entire ecosystem to obtain toxicity data, and that the toxicity data of different species in the ecosystem conform to a certain probability function, i.e., the species sensitivity distribution. First, the normality of the obtained toxicity data is tested. Then, a statistical model is used to fit the pollutant concentration and the cumulative probability of the species sensitivity distribution to calculate the pollutant concentration that can protect most species. This is generally expressed as the concentration at which 5% of species are harmed (HC5), or the concentration at which the 95% protection level is reached. Various distribution models are commonly used for fitting toxicity data, such as the normal distribution model, the log-normal distribution model, the logistic distribution model, and the log-logistic distribution model. This case study uses the log-normal distribution model for fitting.

[0085] The key step in the SSD method is the acquisition and processing of toxicity data. Currently, the 10% effective concentration (EC50) is widely used internationally. 10 (and no-observed-effect concentrations (NOECs), such as those from the United States, Canada, Australia, and the Netherlands. Due to the limited amount of terrestrial biotoxicity data, this case study will also use ECs.) 10 In addition to NOEC, some LC was also applied. 50 Despite numerous and valid criticisms of NOEC, which is widely used as a screening value derivation tool, its application in the derivation and formulation of international screening values ​​is deeply rooted. Using NOEC data not only maintains consistency with human health protection but also has the advantage of being comparable to standards / benchmarks of other countries.

[0086] Ecological receptors are preferentially screened for typical model species of the site area, including soil animals (insects, earthworms, and nematodes), plants, and microbial-dominated soil biological processes (such as respiration, nitrification, organic matter mineralization, and soil enzyme activity). For toxicity tests on terrestrial plants, biomass and root elongation are preferred endpoints; for toxicity tests on soil animals, reproductive rate and growth rate are preferred endpoints; and for toxicity tests on soil ecological processes, inhibition rate of soil ecological processes is preferred.

[0087] The pollutant toxicity data used in this study primarily came from the US EPA's ECOTOX toxicity database (https: / / cfpub epa.gov / ecotox), Web of Science (http: / / www.isiknowledge.com), CNKI (http: / / www.cnki.net), and the raw data used by developed countries to derive ecological screening values. The collected toxicity data can be found in [link to relevant documentation]. Figure 5 .

[0088] Using a log-normal distribution model, the toxicity data were substituted to obtain the SSD curves for arsenic and lead (see...). Figure 6 and Figure 7 ).

[0089] According to the SSD curves, the HC5 for arsenic is 5.74 mg / kg, and the HC5 for lead is 142.53 mg / kg. This means that, based on the site's need to protect 95% of species, the ecological risk screening values ​​for arsenic in the soil are 5.74 mg / kg, and for lead, 142.53 mg / kg.

[0090] Compare pollutant concentration data with the aforementioned ecological risk screening values ​​(see...). Figure 8 It can be concluded that the arsenic and lead concentrations of almost all samples exceeded the above-mentioned ecological risk screening values ​​(except for the lead concentration at tailings dam point 1, which did not exceed the screening value), and the site is preliminarily judged to have a high ecological risk.

[0091] Detailed risk assessment:

[0092] Since the preliminary risk assessment results show that the ecological risk of As and Pb pollution in the soil of the demonstration site is high, a detailed risk assessment is needed. Based on the data obtained from site investigation, experimental research and other processes, a probabilistic method should be used to further assess the ecological risk of the site and obtain a more accurate and reliable risk assessment conclusion.

[0093] Margin of Safety (MOS) 10 The critical value (SSD) is determined by using the cumulative probability distribution curve of biotoxicity data at the 10% level. 10 The critical value at 90% of the cumulative probability distribution curve of pollutant environmental exposure concentration (ECD) 90 The ratio of the toxicity effect distribution curve to the environmental exposure concentration curve of the pollutant is used to characterize the ecological risk level of the target pollutant. Generally speaking, the safety threshold method uses both the pollutant toxicity effect distribution curve and the pollutant environmental exposure concentration curve, and is an extension of the quotient method. (Generally, MOS...) 10 The threshold value is set to 1; MOS 10<1 indicates a high degree of overlap between the toxicity data and the distribution of exposure concentrations and a high risk to soil organisms; MOS10>1 indicates almost no risk to soil organisms.

[0094] Substituting the soil sample survey data from the collection site into Excel, the critical value (ECD) at the 90% of the cumulative probability distribution curve of arsenic environmental exposure concentration was obtained. 90 The critical value (SSD) at the 10% of the cumulative probability distribution curve of biotoxicity data is 2800 mg / kg. 10 The concentration was 7.37 mg / kg, MOS 10 >1 indicates a high ecological risk; the critical value at the 90% probability distribution of cumulative lead environmental exposure concentration (ECD) is [value missing]. 90 The critical value (SSD) at the 10% cumulative probability distribution of biotoxicity data is 6500 mg / kg. 10 The concentration was 182.77 mg / kg, MOS 10 >1. There is a high ecological risk.

[0095] 4.2.3.2 Probability Curve Distribution Method

[0096] The probability curve distribution method is obtained by plotting the probability of exposure concentration exceeding the corresponding effect on the vertical axis and the cumulative probability of toxic effects on the horizontal axis. This curve can describe the probability of exceeding the concentration that produces a specific harmful effect, and the area under the curve represents the magnitude of the potential ecological risk of the chemical substance.

[0097] Will Figure 9 and Figure 10 Substituting the data into Matlab, the probability that a species would be affected when arsenic concentrations exceeded 5% was found to be 0.1629 (see...). Figure 11 The probability of a species being affected when arsenic concentrations exceed 1% is 0.3501 (see...). Figure 12 The probability of a species being affected when lead concentrations exceed 5% is 0.5538 (see...). Figure 13 The probability of a species being affected when arsenic concentrations exceed 1% is 0.6939 (see...). Figure 14 ).

[0098] Characterization of complex pollution risks:

[0099] As early as 1952, Plackett and Hewlett proposed two methods to characterize the toxic effects of compound pollutants: concentration summation (also known as simple similar combined effects) and effect summation (also known as independent combined effects). Later, the two types of predictive equations, concentration summation (CA) and independent effects (IA), were widely used to characterize the toxicity of compound pollution. CA is applicable to situations where all chemical substances have the same mechanism of action and do not affect each other's biological activity, while IA is applicable to situations where chemical substances have different mechanisms of action and affect each other's biological activity.

[0100] The application of concentration summation models to calculate the combined effects or risks of multiple pollutants is based on the premise that these chemicals have similar toxic effects. Therefore, the environmental concentrations of each pollutant are converted into dimensionless toxicity units (HU), meaning that the toxicity data of each pollutant should have similar distribution patterns and the same standard deviation. Figure 10 It can be seen that the standard deviations of the toxicity data for arsenic and lead are quite similar, at 0.4674 and 0.3235, respectively. Furthermore, considering that the toxicity of most combined pollution is concentration-additive (accounting for approximately 70-90%), with only a small portion exhibiting antagonistic or synergistic effects, this case study uses a concentration-additive model to characterize the combined pollution risk of arsenic and lead, as shown in the following formula:

[0101] HI = HO A +HQ B

[0102] MOS of arsenic and lead calculated based on the safety threshold method 10 The MOS transistors are 380 and 35.6 respectively, after recombination. 10 The value is 415.6, MOS 10 >1. There is a high ecological risk.

[0103] The above are merely preferred embodiments of the present invention, intended only to aid in understanding the method and core ideas of this application. The scope of protection of the present invention is not limited to the above embodiments; all technical solutions falling within the scope of the present invention's concept are within its protection. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principles of the present invention should also be considered within the scope of protection of the present invention.

[0104] This invention comprehensively solves the problem that there is no solution in the existing market for ecological risk assessment of complex contaminated soil. Through the steps of rapid assessment, preliminary assessment, detailed assessment and risk characterization, it can make predictions on the pollution risks of different land types and contribute to the safe construction of urbanization.

Claims

1. A method for ecological risk assessment of soil with complex contamination at a site, characterized in that... Includes the following steps: S1: Rapid Risk Identification Phase; S2: Initial Phase Assessment; S3: Second Phase Detailed Assessment; S4: Third-stage composite pollution risk characterization; S1 is based on the rapid observation, measurement and testing of pollutant concentrations and other physical, chemical and biological indicators in the soil or organisms of the assessment area and control area to preliminarily identify whether there are potential risks, and to preliminarily determine the areas that may be at risk and the receptors that may be affected. The receptors are preferentially screened for typical model species in the region, including soil animals, plants, and microbial-dominated soil biological processes; for toxicity tests on terrestrial plants, biomass and root elongation toxicity endpoints are selected; for toxicity tests on soil animals, reproductive rate and growth rate toxicity endpoints are selected; and for toxicity tests on soil ecological processes, the inhibition rate of soil ecological processes is selected. S2 is to take the lower of the screening values ​​derived from the direct exposure pathway and the screening values ​​derived from the uptake pathway as the final screening value. The soil pollutant concentration obtained from the investigation is compared with the derived soil pollution ecological risk screening value to determine whether the risk is acceptable. If it is acceptable, the assessment is terminated. If it is not acceptable, the second stage of detailed assessment is entered. The S3 method is based on pollutant concentration and speciation surveys, pollutant bioavailability surveys and tests, pollutant biotoxicity tests and ecological surveys, and uses the quotient method, index method (i.e., evidence weight method), and probability method to assess the site soil pollution risk. S4 involves conducting a study on the toxic effects of combined pollution. The risk values ​​of different pollutants obtained in the second stage are comprehensively characterized by either concentration summation or effect summation. First, the concentration of residual pollutants in the tissue is obtained and compared with a toxicity reference value. If the ratio is less than 1, the risk of different pollutants is characterized using a concentration summation method, i.e., the following formula is used: ； If the ratio of tissue residual concentration to toxicity reference value is >1, it is classified into different toxicity mechanisms of MeOA. The internal toxicity unit ITUmix for each MeOA is calculated using CA, as follows: ； ； If ITUmix is ​​less than the threshold, it is characterized using the CA formula: ； For values ​​greater than or equal to the threshold, the summation of effects (IA) is used for characterization, as shown in the formula: ； In the formula, HQi represents the ecological risk of a single pollutant, PAFi represents the proportion of damaged biological species by a single pollutant, ITUi is the internal toxicity unit, ICI is the liquid phase concentration of i in the mixture, and IECpi is the effective concentration of i.

2. The method for ecological risk assessment of soil with complex site pollution according to claim 1, characterized in that: The screening values ​​derived from S2 need to be selected based on different land use types to select appropriate ecological receptors, exposure pathways, toxic endpoints, and protection levels.

3. The method for ecological risk assessment of soil with complex pollution at a site according to claim 2, characterized in that: The land use types include industrial land, residential land, park green space, and mines. The ecological receptors for industrial land are microorganisms and soil animals, the exposure pathway is direct exposure, and the protection level is set at 50%. The ecological receptors for residential land are microorganisms, soil animals, and plants, the exposure pathway is direct exposure, and the protection level is set at 60%. The ecological receptors for park green space are microorganisms, soil animals, plants, and birds, the exposure pathways are direct exposure and ingestion, and the protection level is set at 80%. The ecological receptors for mines are microorganisms, soil animals, plants, and higher animals, the exposure pathways are direct exposure and ingestion, and the protection level is set at 80%.

4. The method for ecological risk assessment of soil with complex pollution at a site according to claim 2, characterized in that: The selection principle for the toxicity endpoint is: EC10>EC20>EC25>EC30>EC50>NOEC, where EC represents the toxicity effect data of the pollutant, used to construct the SSD curve, and the 5th percentile on the curve is selected as the screening value.

5. The method for ecological risk assessment of soil with complex pollution at a site according to claim 1, characterized in that: The quotient method is based on information obtained in the detailed assessment phase. The screening values ​​obtained in the first phase are corrected, and the pollutant concentration is compared with the corrected screening values ​​to obtain a risk quotient based on the soil pollution concentration. Alternatively, based on information obtained during the detailed investigation and assessment phase, the biological exposure level can be calculated, and a toxicity reference value can be derived. The biological exposure level can then be compared with the toxicity reference value to obtain a risk quotient based on the biological exposure level.

6. The method for ecological risk assessment of soil with complex pollution at a site according to claim 1, characterized in that: The index method considers indicators related to soil pollution risk, constructs a comprehensive assessment index, and calculates a comprehensive risk index.

7. The method for ecological risk assessment of soil with complex pollution at a site according to claim 1, characterized in that: The probabilistic risk assessment method mainly involves superimposing the probability distribution of pollutant concentration and the probability distribution of toxicity data to obtain probabilistic risk.

8. The method for ecological risk assessment of soil with complex pollution at a site according to claim 1, characterized in that: The quotient method, index method, and probability method can all be used for industrial land, residential land, park green space, and mines.

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