Soil heavy metal pollution ecological risk assessment method and system

Abstract

The invention discloses a soil heavy metal pollution ecological risk assessment method and system, and relates to the technical field of soil pollution risk assess.The method comprises the steps that a topsoil mixed sample in a land parcel needing ecological risk assessment is collected, and the topsoil mixed sample is obtained according to the national soil pollution condition detailed investigation soil sample analysis and test method technical regulation; heavy metal elements in the surface soil mixed sample are analyzed and determined; for the analyzed and determined heavy metal elements, obtaining 10% inhibition effect concentration EC10 of different heavy metal elements on barley, and standardizing the EC10; calculating a risk quotient of each heavy metal element by taking the standardized EC10 as an ecological risk reference value, adding the risk quotients of the heavy metal elements to obtain a total risk quotient of the topsoil mixed sample, and performing ecological risk assessment on the topsoil mixed sample; according to the method, EC10 is taken as an ecological risk reference value, the risk quotient of each heavy metal element is calculated, and then refined ecological risk assessment of soil heavy metal pollution is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of soil pollution risk assessment, and in particular to a soil heavy metal pollution ecological risk assessment method and system. Background Art

[0002] At present, the three waste emissions and surface runoff from industrial activities such as metal mining, smelting and processing, electroplating, leather manufacturing, electronic disassembly sites, phosphate fertilizer production, and coal combustion are continuously bringing heavy metals into the soil environment near the enterprises. The continuous accumulation of heavy metals poses a great risk to the safety of the soil ecosystem, which will not only affect the function and species diversity of the soil ecosystem, but also endanger human health through the food chain. Therefore, the ecological risks of the soil in and around enterprise sites have attracted widespread attention.

[0003] The Hakanson potential ecological risk index method is the most commonly used method for ecological risk assessment of heavy metal contaminated soil, that is, the quotient of the concentration of a certain element in the environment and its environmental background value is multiplied by the corresponding toxicity coefficient. The toxicity coefficient is calculated based on the "abundance principle" (potential biological toxicity is inversely proportional to its abundance) and "release effect". However, there are two problems in the application of this method. On the one hand, the determination of the toxicity coefficient value only clarifies 12 elements with toxicity coefficients. Among them, the biological toxicity response coefficients of 7 elements, mercury, cadmium, arsenic, lead, copper, chromium and zinc are 40, 30, 10, 5, 5, 5, 2, and 1 respectively, and the toxicity coefficients of the five heavy metals, titanium, manganese, vanadium, nickel, and cobalt, are 1, 1, 2, 5, and 5 respectively. These toxicity coefficients are not based on toxicological tests on various organisms in the soil for these pollutants; on the other hand, in the current situation where heavy metals in soil are very common, the potential risk coefficient calculated with soil background values ​​as a reference is too high, which greatly increases the scope and cost of risk control.

[0004] Based on the predicted exposure concentration (PEC) of a pollutant in the environment and the ecological risk threshold (predicted no effect concentration, PNEC), the risk quotient (HQ = PEC / PNEC) is obtained to make ecological risk assessment more accurate and comparable. Estimating the ecological risk threshold of soil heavy metals is the primary task of this soil ecological risk assessment method, and the estimation of the ecological risk threshold needs to be based on the results of ecotoxicological studies of heavy metals.

[0005] The biological composition of soil ecosystems is very complex and diverse. There are 106 to 109 microorganisms in 1 gram of soil, as well as various plants and soil animals. The toxic effects of different species of organisms on the same pollutant can show significant differences due to differences in their respective physiological structures and absorption, conversion and metabolism. In order to protect the vast majority of organisms in the entire ecosystem, the HC5 value (hazardous concentration, the concentration threshold that can protect 95% of organisms) is often obtained based on the 10% inhibitory effect concentration (10% effect concentration, EC10) of ecotoxicological data of more than 8 species at different levels of the food chain, using the species sensitivity distribution curve (SSD) as the risk threshold (Ministry of Ecology and Environment, 2024. Letter on Soliciting Opinions on Three National Environmental Protection Standards including the "Technical Guidelines for the Development of Ecological Safety Soil Environmental Benchmarks (Draft for Comments)" [EB / OL]. [2024-06-02]. https: / / www.mee.gov.cn / xxgk2018 / xxgk / xxgk06 / 201808 / t20180803_629807.html).

[0006] However, the workload of obtaining the results of the ecotoxicological effects of eight organisms is very large, time-consuming and costly. In practice, many ecotoxicological tests that have been carried out are not used for ecological risk assessment, so the selection of species, exposure time and toxicity endpoints are also various, and cannot be fully used for the SSD method; moreover, some common pollutants such as cadmium, chromium, lead, copper, mercury, and arsenic have relatively many research results, but my country has not yet sorted out these data to form a soil ecotoxicological database for risk assessment; the ecotoxicological research results of some emerging pollutants such as rare earth elements are still lacking, and it is difficult to obtain their risk thresholds, which makes it difficult to effectively carry out soil ecological risk assessment. The metal elements specified in the "Standards for Risk Control of Soil Pollution in Agricultural Land for Soil Environmental Quality (Trial)" (GB15618-2018) in my country are only cadmium, mercury, arsenic, lead, chromium, copper, nickel, and zinc. Therefore, it is urgent to explore a simple and feasible ecological risk assessment scheme for soil heavy metals. Summary of the invention

[0007] The purpose of the present invention is to provide a method and system for assessing the ecological risk of soil heavy metal pollution, based on the EC of barley root elongation with heavy metal elements. 10 As an ecological risk reference value, the risk quotient of each heavy metal element is calculated and used for ecological risk assessment of heavy metal pollution in soil samples, thereby improving the accuracy of risk assessment.

[0008] To achieve the above object, the present invention provides the following solutions:

[0009] An ecological risk assessment method for soil heavy metal pollution, comprising the following steps:

[0010] S1. Collect a mixed surface soil sample within the plot to be ecologically risk-assessed, and analyze and determine the heavy metal elements in the mixed surface soil sample according to the "Technical Regulations for the Analysis and Testing Methods of Soil Samples in the Detailed Survey of the National Soil Pollution Status".

[0011] S2. For the heavy metal elements analyzed and determined in S1, obtain the 10% inhibitory effect concentration EC 10 of different heavy metal elements on barley, and perform standardization processing on EC 10 .

[0012] S3. Using the standardized EC 10 as the ecological risk reference value, calculate the risk quotient of each heavy metal element, and sum up the risk quotients of each heavy metal element to obtain the total risk quotient of the mixed surface soil sample; and conduct an ecological risk assessment on the mixed surface soil sample according to the total risk quotient.

[0013] Further, the calculation formula for the total risk quotient in S3 is:

[0014]

[0015] where C D，i is the soil heavy metal content, EC 10 is the geometric mean of the EC 10 of different heavy metals on barley root elongation after standardization. If there are multiple geometric means for the same heavy metal element, the average of these geometric means is used; RQ 4 is the total risk quotient calculated with the standardized EC 10 as the ecological risk reference value.

[0016] Further, the method further includes:

[0017] When it is difficult to obtain the 5% hazard concentration HC 5 of some heavy metal elements, multiply the risk quotient calculated according to the barley EC 10 by 4, and define the risk levels as slight risk, medium risk, strong risk, and extremely strong risk according to the types N of heavy metal elements, <N, (1 - 2)N, (2 - 4)N, and >4N respectively.

[0018] Further, S3 can be replaced with: Using the standardized EC 10 as the ecological risk reference value, calculate the risk quotient of each heavy metal element, and sum up the risk quotients of each heavy metal element to obtain the total risk quotient of the mixed surface soil sample; and conduct an ecological risk assessment on the mixed surface soil sample according to the total risk quotient.

[0019] Obtained the literature on soil heavy metal ecotoxicology research, screened and sorted the literature data, and obtained the 5% hazard concentration HC of some heavy metal elements. 5 ;

[0020] The risk screening value under non-paddy field conditions or the risk screening value under paddy field conditions or HC 5 As a toxicity threshold, a risk quotient corresponding to the toxicity threshold is obtained by calculation;

[0021] An ecological risk assessment is performed based on the risk quotient corresponding to the toxicity threshold.

[0022] Furthermore, the S3, after normalization of EC 10 is the ecological risk reference value, the risk quotient of each heavy metal element is calculated, and the risk quotients of each heavy metal element are added to obtain the total risk quotient of the surface soil mixed sample; the ecological risk assessment of the surface soil mixed sample is performed according to the total risk quotient, which can be replaced by:

[0023] Taking the soil background value as the reference value, calculate the potential ecological risk assessment index value RI corresponding to each heavy metal element in the surface soil mixed sample 1 , according to RI 1 Conducting an ecological risk assessment:

[0024]

[0025] Alternatively, the potential ecological risk assessment index value RI corresponding to each heavy metal element in the surface soil mixed sample is calculated using the risk screening value as the reference value. 2 , and according to RI 2 Conducting an ecological risk assessment:

[0026]

[0027] Where n is the number of metals; RI i is the potential ecological risk assessment index of a single metal; T r，i is the toxicity coefficient of heavy metals, among which the toxicity coefficients of Cd, Ni, Pb, Cu, and Zn are 30, 5, 5, 5, and 1 respectively; C D，i is the measured soil heavy metal content; RS i The risk screening value of agricultural land soil pollution under non-paddy field conditions in the Soil Environmental Quality Agricultural Land Soil Pollution Risk Control Standard (Trial) is used; Cu adopts the risk screening value of agricultural land soil pollution under non-orchard conditions; C R，i is the background value of soil heavy metals, among which the soil heavy metal background paper values ​​of Cd, Ni, Pb, Cu and Zn are 0.14, 12.4, 45.8, 14.8 and 63 respectively.

[0028] Further, the risk screening value under non-paddy field conditions or the risk screening value under paddy field conditions or HC 5 or EC 10 As the toxicity threshold, the risk quotient corresponding to the toxicity threshold is calculated, specifically including:

[0029] The risk screening value under non-paddy field conditions was used as the ecological risk reference value to calculate the risk quotient RQ 1 :

[0030]

[0031] The risk screening value under paddy field conditions was used as the ecological risk reference value to calculate the risk quotient RQ 2 :

[0032]

[0033] HC 5 As the ecological risk reference value, calculate the risk quotient RQ 3 :

[0034]

[0035] Where: n is the amount of heavy metals; RQ i is the risk quotient of a single heavy metal, i is 1, 2, 3, 4; C D，i is the content of heavy metals in soil; RS 1i , RS 2i The HC are the risk screening values ​​of agricultural land soil pollution under non-paddy field conditions and paddy field conditions in the "Soil Environmental Quality Agricultural Land Soil Pollution Risk Control Standard (Trial)" respectively; 5 HC of different heavy metal elements 5 The geometric mean of .

[0036] Furthermore, in S1, the heavy metals in the soil samples are analyzed and measured according to the "Technical Regulations on Analysis and Testing Methods for Soil Samples in the National Soil Pollution Status Detailed Survey", specifically including:

[0037] Soil samples with different degrees of contamination were collected around the contaminated site. The soil samples at each sampling point were air-dried to remove impurities, crushed and sieved, and the soil physical and chemical properties, soil pH value, soil organic matter content, and cation exchange capacity were measured. Heavy metal elements were determined using flame atomic absorption spectrometry.

[0038] The present invention also provides a soil heavy metal pollution ecological risk assessment system, which is applied to the soil heavy metal pollution ecological risk assessment method, and comprises:

[0039] The element determination module is used to collect mixed samples of topsoil in the plots that require ecological risk assessment, and analyze and determine the heavy metal elements in the mixed samples of topsoil according to the "Technical Regulations on Analysis and Testing Methods of Soil Samples for National Soil Pollution Status Detailed Investigation";

[0040] Standardization module, used for analyzing and determining the heavy metal elements in the S1, and obtaining the 10% inhibitory effect concentration EC of different heavy metal elements on barley 10 , and for EC 10 Standardize the process;

[0041] Evaluation module for standardized EC 10 The risk quotient of each heavy metal element is calculated as the ecological risk reference value, and the risk quotients of each heavy metal element are added up to obtain the total risk quotient of the surface soil mixed sample; and the ecological risk assessment of the surface soil mixed sample is performed based on the total risk quotient.

[0042] According to the specific embodiments provided by the present invention, the present invention discloses the following technical effects: the soil heavy metal pollution ecological risk assessment method and system provided by the present invention sorts out some ecotoxicological research results of heavy metals and metalloids, and uses them in soil ecological evaluation; the four risk quotients and two potential ecological risk values ​​calculated by different reference values ​​of 20 samples all show extremely significant correlation (P<0.01). 10 The risk quotient was calculated by using the HC value as the reference threshold, and the proportion of extremely high risk in the 20 samples was 35%. 5 If it is difficult to obtain, use barley EC 10 The soil heavy metal pollution risk quotient is calculated as the reference value by multiplying the risk quotient by 4. The soil risk quotient of a single element is defined as slight risk, medium risk, strong risk, and extremely strong risk level according to <1, 1-2, 2-4, and >4, respectively, achieving a more refined ecological risk assessment. This method provides a simple and feasible ecological risk assessment method, reduces the risk of ecosystem risk management, has a more comprehensive management scope, and is less costly. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0044] Figure 1 Flow chart of the method for ecological risk assessment of soil heavy metal pollution in an embodiment of the present invention;

[0045] Figure 2 This is a ranking diagram of EC10 values ​​of different heavy metals on barley according to the embodiments of the present invention;

[0046] Figure 3 is the risk quotient of the soil sample in the embodiment of the present invention;

[0047] Figure 4 It is the potential ecological risk index (optimized) of the soil sample in the embodiment of the present invention. DETAILED DESCRIPTION

[0048] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of 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.

[0049] The purpose of the present invention is to provide a method and system for assessing the ecological risk of soil heavy metal pollution, based on the EC of barley root elongation with heavy metal elements. 10 As an ecological risk reference value, the risk quotient of each heavy metal element is calculated and used for ecological risk assessment of heavy metal pollution in soil samples, thereby improving the accuracy of risk assessment.

[0050] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0051] Example 1

[0052] The present invention summarizes the ecotoxicological research results of several heavy metals and obtains the EC of barley root elongation of some heavy metals. 10 (hereinafter referred to as barley EC 10 ) as reference values ​​for soil ecological risk assessment; and apply them to the ecological risk assessment of soil in and around the enterprise site, and compare and analyze them with soil risk screening values ​​and environmental background values ​​as reference values, providing a research basis for a simple and feasible ecological risk assessment method for soil heavy metals and the screening of soil priority pollutants.

[0053] like Figure 1 As shown, the soil heavy metal pollution ecological risk assessment method provided by the embodiment of the present invention includes the following steps:

[0054] S1. Collect mixed samples of topsoil from the plots that require ecological risk assessment, and analyze and determine the heavy metal elements in the mixed samples of topsoil according to the "Technical Regulations on Analysis and Testing Methods of Soil Samples for National Soil Pollution Status Detailed Investigation";

[0055] S2. Analyze and determine the heavy metal elements in S1 to obtain the 10% inhibitory effect concentration EC of different heavy metal elements on barley 10 , and standardize EC 10 ;

[0056] S3. Using the standardized EC 10 as the ecological risk reference value, calculate the risk quotient of each heavy metal element, and sum up the risk quotients of each heavy metal element to obtain the total risk quotient of the surface soil mixed sample; and conduct an ecological risk assessment on the surface soil mixed sample according to the total risk quotient.

[0057] In this embodiment, the calculation formula of the total risk quotient in S3 is:

[0058]

[0059] Among them, C D，i is the soil heavy metal content, EC 10 is the geometric mean of the EC 10 of different heavy metals on the root elongation of barley after standardization. If there are multiple geometric means for the same heavy metal element, the average of these geometric means is used; RQ 4 is the total risk quotient calculated with the standardized EC 10 as the ecological risk reference value.

[0060] When it is difficult to obtain the 5% hazard concentration HC 5 of some heavy metal elements, multiply the risk quotient calculated according to the barley EC 10 by 4, and define it as slight risk, medium risk, strong risk, and extremely strong risk levels according to the types N of heavy metal elements, <N, (1 - 2)N, (2 - 4)N, and >4N respectively.

[0061] In a further embodiment, S3, using the standardized EC 10 as the ecological risk reference value, calculate the risk quotient of each heavy metal element, and sum up the risk quotients of each heavy metal element to obtain the total risk quotient of the surface soil mixed sample; and conduct an ecological risk assessment on the surface soil mixed sample according to the total risk quotient, can be replaced by:

[0062] 1) Obtain the literature on the ecological toxicology research of soil heavy metals, and screen and sort out the data in the literature to obtain the 5% hazard concentration HC 5 of some heavy metal elements;

[0063] 2) Using the risk screening value under non-paddy field conditions or the risk screening value under paddy field conditions or HC 5 as the toxicity threshold, calculate the risk quotient corresponding to the toxicity threshold through calculation. The specific formula is:

[0064] The risk screening value under non-paddy field conditions was used as the ecological risk reference value to calculate the risk quotient RQ 1 :

[0065]

[0066] The risk screening value under paddy field conditions was used as the ecological risk reference value to calculate the risk quotient RQ 2 :

[0067]

[0068] HC 5 As the ecological risk reference value, calculate the risk quotient RQ 3 :

[0069]

[0070] Where: n is the amount of heavy metals; RQ i is the risk quotient of a single heavy metal, i is 1, 2, 3, 4; C D，i is the content of heavy metals in soil; RS 1i , RS 2i The HC are the risk screening values ​​of agricultural land soil pollution under non-paddy field conditions and paddy field conditions in the "Soil Environmental Quality Agricultural Land Soil Pollution Risk Control Standard (Trial)" respectively; 5 HC of different heavy metal elements 5 The geometric mean of

[0071] 3) Conducting ecological risk assessment based on the risk quotient corresponding to the toxicity threshold.

[0072] In a further embodiment, the S3 is based on the normalized EC 10 is the ecological risk reference value, the risk quotient of each heavy metal element is calculated, and the risk quotients of each heavy metal element are added to obtain the total risk quotient of the surface soil mixed sample; the ecological risk assessment of the surface soil mixed sample is performed according to the total risk quotient, which can also be replaced by:

[0073] Taking the soil background value as the reference value, calculate the potential ecological risk assessment index value RI corresponding to each heavy metal element in the surface soil mixed sample 1 , according to RI 1 Conducting an ecological risk assessment:

[0074]

[0075] Alternatively, the potential ecological risk assessment index value RI corresponding to each heavy metal element in the surface soil mixed sample is calculated using the risk screening value as the reference value. 2 , and according to RI 2Conducting an ecological risk assessment:

[0076]

[0077] Where n is the number of metals; RI i is the potential ecological risk assessment index of a single metal; T r，i is the toxicity coefficient of heavy metals, among which the toxicity coefficients of Cd, Ni, Pb, Cu, and Zn are 30, 5, 5, 5, and 1 respectively; C D，i is the measured soil heavy metal content; RS i The risk screening value of agricultural land soil pollution under non-paddy field conditions in the Soil Environmental Quality Agricultural Land Soil Pollution Risk Control Standard (Trial) is used; Cu adopts the risk screening value of agricultural land soil pollution under non-orchard conditions; C R，i is the background value of soil heavy metals, among which the soil heavy metal background paper values ​​of Cd, Ni, Pb, Cu and Zn are 0.14, 12.4, 45.8, 14.8 and 63 respectively.

[0078] In a further embodiment, in S1, heavy metals in soil samples are analyzed and measured according to the "Technical Regulations on Analysis and Testing Methods for Soil Samples in the National Soil Pollution Status Detailed Investigation", specifically including:

[0079] Soil samples with different degrees of contamination were collected around the contaminated site. The soil samples at each sampling point were air-dried to remove impurities, crushed and sieved, and the soil physical and chemical properties, soil pH value, soil organic matter content, and cation exchange capacity were measured. Heavy metal elements were determined using flame atomic absorption spectrometry.

[0080] In this embodiment, the EC of barley root elongation can also be obtained according to the following method: 10 value:

[0081] If the target pollutant is not listed in Table 1, the EC values ​​for barley root elongation were obtained from the literature. 10 Value, and normalized: Standardized EC 10 =EC in the original text 10 *3.8% / percentage of organic matter in the literature. If the literature contains organic carbon content, the organic matter content is calculated as organic matter = organic carbon * 1.724 and then normalized. If different literature has different EC values ​​for barley root elongation, 10 , then calculate the EC of barley root elongation in each literature 10 The geometric mean is taken as the final reference value of the element;

[0082] If the EC value of barley root elongation for a certain element is not found in the literature, 10If the value is not obtained, the barley seed germination test and root elongation test are carried out according to "OECD 208 Effects of Chemical Substances on Seedling Emergence Rate and Seedling Growth of Higher Plants in Soil" to obtain the EC value of barley root elongation of the pollutant. 10 value.

[0083] Table 1 Effects of different heavy metals on the EC of barley root elongation after standardized treatment 10 value

[0084]

[0085] Example 2

[0086] The present embodiment is a specific case of the method described in Example 1, and compares the method of calculating the risk quotient according to other toxicity thresholds.

[0087] 1. Acquisition of ecotoxicological literature and processing of relevant data:

[0088] In Chinese and English databases such as CNKI, Wanfang Data, VIP Data, Elsevier and Springer, we searched for heavy metal elements and "soil" as keywords to obtain literature on soil heavy metal ecotoxicology research. At the same time, we screened and sorted the data in the literature to obtain the HC values ​​of some elements. 5 Among them, some heavy metal elements were not found in HC 5 , then other ecotoxicological data of soil were collated.

[0089] Select EC in toxicological data 10 Barley, a relatively large and frequently occurring species, was used as the test species. 10 " was used as the key word to organize the data. Since different studies used different soil types, it is necessary to 10 Different soil characteristics can affect the toxicity of heavy metals, and organic matter has been considered to be one of the most influential factors for EC 10 The data is standardized:

[0090]

[0091] Where: EC 10(e) EC for the collated literature 10 OM standard is the organic matter content of artificial soil, which is 3.8%; OM inexperiment is the organic matter content of the literature experiment;

[0092] The meaning of this formula is: Standardized EC 10 =EC in the original text 10 *3.8% / percentage of organic matter in the literature;

[0093] After that, the geometric mean was taken after standardization to compare and analyze the order of their toxicity.

[0094] 2. HC of nine common heavy metals in the literature 5 And toxic effect value:

[0095] A total of 308 relevant Chinese and English literatures were retrieved, from which the HC values ​​of nine metal elements, including lead, cadmium, antimony, zinc, chromium, nickel, copper, mercury and cobalt, were collected. 5 There are 17 values ​​in total, as shown in Table 1. 5 HC under different soil conditions from the literature 5 range, and then find its geometric mean to obtain the HC of each element 5 The order of the mean values ​​of mercury is: mercury < cadmium < chromium < cobalt < copper < antimony < nickel < zinc < lead. 5 0.53 mg kg -1 and 1.2 mg kg -1 , which is much lower than other elements, indicating that its ecotoxicity is relatively the greatest, followed by cadmium and chromium. 5 The average geometric mean is 157.04 mg kg -1 and 111.43 mg kg -1 , which is 140 to 197 times that of mercury, and has lower ecological toxicity. 5 The difference is the largest, reaching 2 orders of magnitude. 5 There are 4 and 3 related papers respectively. In these papers, the HC 5 Close, but there is a HC in the literature on lead 5 Much higher than the other two articles; HC of the same metal 5 The possible reasons for the differences are the test conditions, organism sensitivity, effective state of metal elements, test methods and other factors.

[0096] Table 1 Ecotoxicological HC of heavy metals in soil 5 Value (mg kg -1 )

[0097]

[0098]

[0099] Note: HC 5 It refers to the pollutant concentration when the cumulative probability of affected species reaches 5%, or the pollutant concentration at which 95% of species can be effectively protected.

[0100] Since there is no HC of elements molybdenum, arsenic, and vanadium in the above literature5 Therefore, their toxic effect data are summarized in Table 2. There are relatively many ecotoxicological studies on molybdenum, and the tested species include multiple plants (barley, rapeseed, red clover, ryegrass and tomato) and Eisenia fetida. The lowest and highest toxic effect values ​​of different species are similar in magnitude, and the EC50 value of Eisenia fetida is significantly lower than the LC50 of plants. 50 This indicates that E. deficient is more sensitive to the toxic effects of molybdenum pollution in the soil than plants. Compared with plants such as barley and ryegrass, red clover shows a higher sensitivity to molybdenum. 10 The geometric mean is 418.41 mg kg -1 , E.C. 50 The geometric mean is 1006.76 mg kg -1 ; Molybdenum is relatively less toxic to tomatoes, and its EC 10 The geometric mean is 770.91 mg kg -1 , E.C. 50 The geometric mean is 2055.90 mg kg -1 , nearly twice that of red clover. Among the toxic effect values ​​of molybdenum, arsenic and vanadium on Eisenia deliciosa, vanadium has the lowest toxic effect value and the largest toxic effect.

[0101] Table 2 No HC 5 Soil ecotoxicological study results of some heavy metals with low values ​​(mg·kg -1 )

[0102]

[0103] Note: ECx: the concentration that causes X% toxic effect in organisms within a certain time interval; LCx: the concentration that causes X% death in organisms within a certain time interval; LD 50 : The concentration of a chemical that causes the death of half of the organisms within a certain time interval.

[0104] Because most of the toxicological studies of these metals use barley root elongation as the evaluation endpoint, in order to compare their toxic effects, the EC values ​​of 10 heavy metal elements, including copper, nickel, lead, zinc, cadmium, antimony, cobalt, chromium (III), chromium (VI), and molybdenum, on barley were screened and sorted out. 10 range and experimental soil organic matter content, a total of 19 literature data. As shown in Table 3, the EC 10 Range: 1.3-2.5 mg kg -1 , which is lower than other elements, indicating that its toxicity is relatively the greatest, followed by chromium and nickel. 10 Range: 385.9~7277.5mg·kg -1 , the higher the value, the less toxic it is.10 The range was the largest, reaching 3 orders of magnitude. 10 There are many studies on this, and there are 3 related papers. 10 The different ranges may be due to differences in soil physical and chemical properties, experimental conditions and other factors.

[0105] Table 3 EC values ​​of different heavy metals on barley 10 value

[0106]

[0107]

[0108] Note: Organic matter = organic carbon * 1.724.

[0109] Barley EC of most heavy metal elements 10 There are multiple research results, and the differences are quite large; for the same element, if there are multiple EC 10 If the same element has EC values ​​from multiple different documents, the geometric mean is calculated. 10 value, then take the average value to get the final EC 10 The final EC 10 The value results are sorted, such as Figure 2 Barley shows different toxicity sensitivities to different metal element pollution. The EC 10 The value is relatively small, 1.79 mg kg -1 , followed by hexavalent chromium, which is 38.46 mg kg -1 , that is, barley showed a high toxic sensitivity to cadmium and hexavalent chromium. The EC values ​​of antimony and molybdenum were 10 Relatively large, 2410.40 mg kg -1 and 2544.39 mg kg -1 , which are 1345 and 1420 times that of cadmium. It can be seen that cadmium is relatively toxic to barley, while antimony or molybdenum is less toxic. 10 The order of the mean values ​​is: cadmium < chromium (VI) < copper < chromium (III) < nickel < lead < cobalt < zinc < antimony < molybdenum. Compared with the risk screening values ​​of the corresponding metals under non-paddy field conditions (copper under non-orchard conditions) in the "Soil Environmental Quality Agricultural Land Soil Pollution Risk Control Standard (Trial)" (GB15618-2018), the lower the screening value, the greater the toxicity. The order of the toxicity of the relevant metals is cadmium> copper> nickel> lead> zinc; compared with barley EC 10 The order is consistent.

[0110] 3. Collect soil samples and obtain their physical and chemical properties and heavy metal content:

[0111] Twenty soil samples with different degrees of pollution were collected from sites or surrounding environments of some key heavy metal-related industries in Guangdong Province (electroplating, lead-zinc mining areas, steel mills, smelters, etc.). The surface soil of 0-20 cm was collected. The soil samples at each sampling point were air-dried to remove debris, crushed and passed through 60 and 100 nylon mesh sieves. The physical and chemical properties of the soil were determined according to the reference (Bao Shidan, 2000) and relevant standards. The soil pH value was determined by the potentiometric method with a water-soil ratio of 2.5:1 (HJ962-2018); the soil organic matter content was determined by the concentrated sulfuric acid-potassium dichromate external heating method (GB / T19656-006); and the cation exchange capacity was determined by the ammonium acetate extraction method (NY / T1121.5-2006). After the soil samples were digested by nitric acid-hydrochloric acid-hydrofluoric acid microwave method, cadmium, lead, copper, zinc and nickel were determined by flame atomic absorption spectrometry (Z-33000, Hitachi, Japan).

[0112] The physicochemical properties and heavy metal contents of the 20 soil samples are shown in Table 4. The physicochemical properties and heavy metal contents of each sampling point vary greatly. The pH, organic matter content and cation exchange capacity of each sample are 3.79-8.32 and 1.25-57.44 g·kg, respectively. -1 , 3.91~18.87cmol·kg -1 The contents of metal Pb, Cd, Cu, Zn and Ni are 26.87-2146.36 mg kg -1 , 0.13~63.36mg·kg -1 4.14~3463.83mg·kg -1 36.34~10665.07mg·kg -1 and 13.87~702.35mg·kg -1 The Cd contents of samples 17 and 19 were as high as 63.36 and 49.59 mg kg -1 The Cd content of samples 7 and 9 was the second highest, at 20 mg kg -1 About; Sample 9 has the highest Pb content, exceeding 2100 mg kg -1 The Pb content of sample 1 and sample 7 is next highest, which is 717.23 mg·kg -1 and 629.37 mg kg -1 The Cu and Zn contents of sample 17 were as high as 3463.83 mg·kg -1 and 10665 mg kg -1 ; The Ni content of sample 14 is as high as 702.35 mg·kg -1 , while the Ni content of most other samples is less than 50 mg·kg -1。The average heavy metal contents of 20 soil samples were in the order of Cd < Ni < Pb < Cu < Zn, and their average values were 9.07 mg·kg -1 、65.95 mg·kg -1 、288.63 mg·kg -1 、448.8 mg·kg -1 and 1357.61 mg·kg -1 respectively. The coefficients of variation of Pb, Cd, Cu, Zn, and Ni were 1.69, 1.93, 1.88, 1.84, and 2.28 respectively, all belonging to strong variation, verifying that there are significant differences in the heavy metal pollution levels at different sampling points, which is suitable for the exploration, analysis, and comparison of risk assessment methods.

[0113] Table 4 Physical and chemical properties and heavy metal contents of soil samples

[0114]

[0115]

[0116] 4. The ecological risk assessment results based on different evaluation criteria are as follows:

[0117] The risk quotients of soil samples were calculated and ranked. The higher the value, the higher the risk. The results are as Figure 3 shown. Four risk quotients (risk quotient, RQ) were calculated using the risk screening values under non-paddy field and paddy field conditions specified in GB15618-2018, HC5, and the EC of barley 10 as toxicity thresholds respectively, namely risk quotient 1, risk quotient 2, risk quotient 3, and risk quotient 4. The overall trends of the four risk quotients of different samples were relatively consistent. The lowest-risk soil samples for these risk quotients were sample 18 (1.09), sample 18 (0.94), sample 2 (1.29), and sample 2 (0.32) respectively. However, sample 2 was also in the low-risk range in the calculations of risk quotient 1 and risk quotient 2, which were 1.55 and 1.49 respectively. The reason for the low risk quotient of sample 18 may be that the pH is relatively high, so the value of RS i in the "Soil Environmental Quality Risk Control Standards for Agricultural Land Soil Pollution (Trial)" (GB15618-2018) is relatively high, resulting in a relatively small risk quotient value after calculation. The highest-risk soil samples for risk quotient 1, risk quotient 2, risk quotient 3, and risk quotient 4 were all sample 17 (177.04, 150.33, 263.21, 73.70). The ranges of risk quotient 1, risk quotient 2, risk quotient 3, and risk quotient 4 for each sample were: 1.1 - 177, 0.9 - 150, 1.3 - 263, and 0.3 - 74 respectively. The order of the four risk quotients calculated using different reference values was: risk quotient 4 < risk quotient 2 < risk quotient 1 < risk quotient 3. Using HC 5The highest risk quotient calculated as the ecological risk reference value is based on barley EC 10 The two risk quotients calculated using the risk screening values ​​of paddy fields and non-paddy fields are close, probably HC 5 The reference risk quotient value is 57% to 85%. Judging from this result, the risk screening value specified in my country's standards is relatively rigorous and reasonable.

[0118] HC 5 The risk quotient used as the reference value is calculated. Each element is defined as a slight risk, a medium risk, a strong risk, and an extremely strong risk level as <1, 1-2, 2-4, and >4, respectively. The five elements are defined as a slight risk, a medium risk, a strong risk, and an extremely strong risk level as <5, 5-10, 10-20, and >20, respectively. 5 The risk quotient calculated as the ecological risk reference value is based on the barley EC 10 The reference value is 2.20 to 4.33 times, so barley EC 10 The calculated risk value quotient was multiplied by 4, and then <5, 5-10, 10-20 and >20 were defined as slight risk, medium risk, strong risk and extremely strong risk levels respectively. 5 EC 10 The numbers of samples of slight risk, medium risk, strong risk and extremely strong risk levels calculated for the reference values ​​are 8, 2, 2, 8, 6, 3, 4, 7 respectively. The numbers corresponding to these two reference values ​​are relatively close.

[0119] Taking the risk screening value of non-paddy fields and the soil background value of Shaoguan, Guangdong Province as reference values, the calculated potential ecological risk index values ​​RI of the five elements in 20 soil samples were 14-3382 and 41-14952, which were much larger than the above risk quotient values. Figure 4 The RI classification standard proposed in the document "HAKANSON L, 1980. An ecological risk index for aquatic pollution control: A sedimentological approach. Water Res. 14, 975-1001" is RI < 150 (slight ecological risk), 150 ≤ RI < 300 (medium ecological risk), 300 ≤ RI < 600 (strong ecological risk), RI ≥ 600 (very low ecological risk).

[0120] However, the RI classification standard should take into account the type and quantity of pollutants, so the classification standard is adjusted according to the type and number of pollutants studied in this embodiment. This embodiment is adjusted with reference to the adjustment method proposed in "Ma Jianhua, Wang Xiaoyun, Hou Qian, et al., 2011. Heavy metal pollution and potential ecological risks of surface dust in a kindergarten in a certain city [J]. Geographical Research, 30(03): 486-495", that is, firstly, the RI classification value (1.13) of the unit toxicity response coefficient is obtained by dividing the first-level classification limit value (150) of Hakanson by the total value (133) of the toxicity response coefficients of 8 pollutants; then, the RI classification value of the unit toxicity response coefficient is multiplied by the total value (46) of the toxicity response coefficients of the 5 heavy metals of the present invention and the ten-digit integer is taken to obtain the first-level RI classification limit value (51.98≈50) of the present invention; the classification values ​​of other levels are obtained by multiplying the classification values ​​of the previous level by 2. Finally, the evaluation criteria for each risk level are: RI < 50 for slight ecological risk, 50 ≤ RI < 100 for moderate ecological risk, 100 ≤ RI < 200 for strong ecological risk, and RI ≥ 200 for very strong ecological risk.

[0121] According to the readjusted grading standards, among the 20 soil samples, the numbers of samples with slight risk, moderate risk, strong risk and extremely strong risk levels in the potential ecological risk index values ​​PERI1 and PERI2 calculated based on the soil background value and risk screening value were 1, 2, 2, 15 (RI was 216-14952), 4, 3, 4, 9 (RI was 208-3383), respectively. The risk levels estimated based on the soil background value were mostly higher than those of other methods, and the highest risk value was close to 15000.

[0122] Table 5 Risk quotient and potential ecological risk index of 20 soil samples based on different reference values

[0123]

[0124]

[0125] Note: RQ1, RQ2, RQ3, and RQ4 use the risk screening value (non-paddy field and paddy field) specified in GB15618-2018, HC5, and barley root elongation EC10 as toxicity thresholds to calculate the risk quotient (RQ); 2) RI1 and RI2 use the risk screening value (non-paddy field) and Guangdong Shaoguan soil background value as ecological risk thresholds to calculate the potential ecological risk assessment index.

[0126] 5. Correlation analysis:

[0127] The Spearman rank correlation analysis (Table 5) and canonical correlation analysis were performed on the ranking of risk quotients and potential ecological risk assessment indices. As shown in Table 6, each risk quotient and each potential ecological risk index has a strong correlation. Risk quotient 3 is extremely significantly correlated with risk quotient 1, risk quotient 2, risk quotient 4, potential ecological risk index RI1 and potential ecological risk index RI2, with correlation coefficients of 0.937, 0.925, 0.950, 0.896 and 0.896, respectively. Risk quotient 4 is also extremely significantly correlated with risk quotient 1, risk quotient 2, risk quotient 3, potential ecological risk index PERI1 and potential ecological risk index RI2, with correlation coefficients of 0.977, 0.961, 0.950, 0.929 and 0.926, respectively. The correlation coefficient between risk quotient 4 and other risk values ​​is slightly higher than the corresponding value of risk quotient 3. From the typical correlation analysis, it can be seen that there is a significant correlation between the six variables of risk quotient and potential ecological risk index, and the correlation reaches 0.996 (P=0.000, P<0.050). Therefore, it can be considered that these six methods can be used for ecological risk assessment, but corresponding risk classification standards should be formulated according to each assessment method to obtain more accurate risk assessment results.

[0128] Table 6 Spearman rank correlation analysis

[0129]

[0130]

[0131] Note: **The correlation is significant at the 0.01 level (two-tailed).

[0132] Jiang Bing et al. (2022) used the paddy field risk screening value and background value specified in GB15618-2018 as reference values ​​to conduct ecological risk assessment of Cd, Hg, As, Cr, Ni, Cu, Zn and Pb in agricultural soil of Nanzhanglou Village, Qingzhou City, Weifang City, Shandong Province. The results showed that the risk values ​​of individual elements were 0.36-7.12 and 1.35-69.17, respectively. When the soil background value was used as the reference value for potential ecological risk assessment, its ecological risk value was 3.75-9.71 times that of the risk screening value. Shi Shuaihang et al. (2022) used the background value to calculate the average ecological risk index of Pb and Cd in the No. 1 lead-zinc mine in a mineral mining area in the southwest region, which was as high as 2095.05 and 3658.50, respectively. Similarly, in this embodiment, the potential ecological risk index values ​​RI of Cd, Ni, Cu, Zn and Pb calculated based on the risk screening value of non-paddy fields specified in GB15618-2018 and the soil background value of Shaoguan, Guangdong Province are 14-3382 and 41-14952, respectively. The latter is 2.92-4.42 times of the former, and the highest value of the latter is close to 15000. According to the original regulations, more than 320 is an extremely strong ecological risk. The PERI of sample points 4 and 17 are 408.2 and 14951.7, respectively, both of which are extremely strong ecological risks, and there is no difference in risk level, but the PERI value of the latter is 36.63 times that of the former, and the latter is 14543.5 larger than the former. In addition, for the assessment of areas with high background values, the ecological risk will also be weakened.

[0133] Finally, the proportion of soil ecological risks at various levels based on different reference values ​​in 20 samples was obtained, as shown in the following table:

[0134] Table 7 Proportion of soil ecological risks at various levels based on different reference values ​​in 20 samples (%)

[0135]

[0136]

[0137] Note: (1) Each element of RQ1, RQ2, and RQ3 is defined as a slight risk, a medium risk, a strong risk, and an extremely strong risk level as <1, 1-2, 2-4, and >4, respectively. The total risk of the five elements is defined as a slight risk, a medium risk, a strong risk, and an extremely strong risk level as <5, 5-10, 10-20, and >20, respectively. After RQ4*4 is multiplied, the total risk is further defined as a slight risk, a medium risk, a strong risk, and an extremely strong risk level as <5, 5-10, 10-20, and >20, respectively. (2) The risk level of RI is adjusted based on the type of element according to the adjustment method proposed by Ma Jianhua et al. (2011): RI < 50 is a slight ecological risk, 50 ≤ RI < 100 is a medium ecological risk, 100 ≤ RI < 200 is a strong ecological risk, and RI ≥ 200 is a very strong ecological risk.

[0138] In summary, in this embodiment, the risk screening values ​​(under non-paddy field and paddy field conditions) and HC 5 and EC of barley 10 Four risk quotients (RQ) were calculated as toxicity thresholds, and the potential ecological risk assessment index was calculated using the risk screening value and the soil background value of Shaoguan, Guangdong as ecological risk reference values. The results showed that there was a strong correlation between the four risk quotients and the two potential ecological risk indices. 10 The correlation coefficients between the risk quotient calculated as the reference value and the other three risk quotients and two potential ecological risk indices were 0.977, 0.961, 0.950, 0.929, and 0.929, respectively. 5 The risk quotient used for reference value calculation is defined as slight risk, medium risk, strong risk, and extremely strong risk level for each heavy metal element according to the risk quotient <1, 1-2, 2-4, and >4, respectively. The five elements are defined as slight risk, medium risk, strong risk, and extremely strong risk level according to the risk quotient <5, 5-10, 10-20, and >20, respectively. 5 The risk quotient calculated as the ecological risk reference value is based on the barley EC 10 The reference value is 2.20 to 4.33 times, so we use barley EC 10 The calculated risk value quotient is multiplied by 4, and then <5, 5-10, 10-20 and >20 are defined as slight risk, medium risk, strong risk and extremely strong risk levels respectively. The above potential ecological risk value assessment results are also very strong ecological risk level samples 4 and 17 RQ4 multiplied by 4, which are 5.68 and 483.12 respectively, and the risk levels are medium risk and extremely strong risk respectively, with very significant differences.

[0139] Among the 20 soil samples, HC 5 EC 10 The percentages of samples with slight risk, medium risk, strong risk and extremely strong risk levels calculated for reference values ​​are 40%, 10%, 10% and 40%, 30%, 15%, 20% and 35%, respectively, which are quite close. The percentages of samples with slight risk, medium risk, strong risk and extremely strong risk levels in the potential ecological risk index values ​​RI1 and RI2 calculated with soil background value and risk screening value as reference values ​​are 5%, 10%, 10% and 75%, 20%, 15%, 20% and 45%, respectively. The percentage of samples with extremely strong risk level calculated with soil background value as reference is 1.67-2.14 times that of other methods, which is much greater than the evaluation results of other methods. Therefore, the overall ecological risk assessed by the potential ecological risk index method is much greater than the result of the entropy value method. In HC 5If it is difficult to obtain, use barley EC 10 The result of calculating the risk quotient by 4 times as the reference value, the adjusted risk quotient of a single element is defined as slight risk, moderate risk, strong risk, and extremely strong risk level according to <1, 1-2, 2-4, and >4, respectively, which can be used for a relatively more refined ecological risk assessment. In the future, the EC of other species such as rice seed germination and root elongation can also be studied. 10 , as a feasibility study of risk assessment thresholds.

[0140] 6. Conclusion:

[0141] 1) HC 5 and barley EC 10 The geometric means showed that mercury, cadmium and chromium had higher ecotoxicity, while lead, zinc, antimony and molybdenum had relatively lower ecotoxicity.

[0142] 2) By using the risk screening values ​​(under non-paddy field and paddy field conditions) specified in GB15618-2018, HC 5 and barley EC 10 Four risk quotients (RQs) were calculated as toxicity thresholds, and the risk screening value and the soil background value in Shaoguan, Guangdong were used as ecological risk reference values ​​to calculate the potential ecological risk assessment index; the four risk quotients and the two potential ecological risk indices were significantly correlated. 10 The correlation coefficients between the risk quotient used for reference value calculation and the other three risk quotients and two potential ecological risk indices were 0.977, 0.961, 0.950, 0.929, and 0.929, respectively.

[0143] 3) When pollution is widespread, the potential ecological risk index value calculated using background values ​​as a reference is too high, which greatly increases the scope and cost of heavy metal pollution ecological risk control. 5 If it is difficult to obtain, use barley EC 10 The risk quotient is calculated as a reference value and multiplied by 4. The adjusted risk quotient of a single element is defined as slight risk, moderate risk, strong risk and extremely strong risk levels according to <1, 1-2, 2-4 and >4, respectively, which allows for a relatively more refined ecological risk assessment.

[0144] In summary, the present invention provides a method for 10 The method of obtaining the risk quotient as a reference value is simple and easy to use. In addition, many heavy metal elements have relevant research results on barley root elongation, which can be directly used to calculate the risk quotient; even if there are no such results, the standard method of "OECD 208 Effects of Chemical Substances on Seedling Emergence Rate and Seedling Growth of Higher Plants in Soil" can be used to obtain the risk quotient, which is also relatively easy and feasible. 10The result obtained by multiplying the risk quotient by 4 times as the reference value is calculated. The adjusted risk quotient of a single element is defined as slight risk, medium risk, strong risk, and extremely strong risk level according to <1, 1-2, 2-4, and >4, respectively, which can be used for relatively refined and rapid preliminary ecological risk assessment. The technical solution of the present invention provides a simple and feasible ecological risk assessment method, reduces the risk of ecosystem risk management, has a more comprehensive management scope, and lowers the cost. And HC 5 Obtaining a large number of toxicological results from various organisms is required, which greatly increases the time and cost of risk assessment.

[0145] Example 3

[0146] The embodiment of the present invention further provides a soil heavy metal pollution ecological risk assessment system, which is applied to the soil heavy metal pollution ecological risk assessment method described in Example 1, and comprises:

[0147] The element determination module is used to collect mixed samples of topsoil in the plots that require ecological risk assessment, and analyze and determine the heavy metal elements in the mixed samples of topsoil according to the "Technical Regulations on Analysis and Testing Methods of Soil Samples for National Soil Pollution Status Detailed Investigation";

[0148] Standardization module, used for analyzing and determining the heavy metal elements in the S1, and obtaining the 10% inhibitory effect concentration EC of different heavy metal elements on barley 10 , and for EC 10 Standardize the process;

[0149] Evaluation module for standardized EC 10 The risk quotient of each heavy metal element is calculated as the ecological risk reference value, and the risk quotients of each heavy metal element are added up to obtain the total risk quotient of the surface soil mixed sample; and the ecological risk assessment of the surface soil mixed sample is performed based on the total risk quotient.

[0150] In summary, the method of the present invention is simple and easy to implement. Many heavy metal elements have relevant research results on barley root elongation, which can be directly used for the calculation of risk quotients; even if there is no EC for barley root elongation, 10 The values ​​can be easily obtained using the standard method of "OECD 208 Effects of Chemical Substances on Seedling Emergence and Growth of Higher Plants in Soil". 10 The result of calculating the risk quotient by 4 times as the reference value is obtained. The adjusted risk quotient of a single element is defined as slight risk, medium risk, strong risk, and extremely strong risk level according to <1, 1-2, 2-4, and >4, respectively, which can be used for relatively refined rapid preliminary ecological risk assessment. 5 Obtaining a large number of toxicological results from various organisms is required, which greatly increases the time and cost of risk assessment.

[0151] The remaining technical features in this embodiment can be flexibly selected by those skilled in the art according to actual conditions to meet different specific practical needs. However, it is obvious to those skilled in the art that it is not necessary to adopt these specific details to implement the present invention. In other examples, in order to avoid confusing the present invention, the well-known components, structures or parts are not specifically described, which are all within the technical protection scope defined by the technical solution claimed for protection in the claims of the present invention.

[0152] Modifications and changes made by those skilled in the art that do not depart from the spirit and scope of the present invention should be within the scope of protection of the claims attached to the present invention. In the above description, a large number of specific details are set forth in order to provide a thorough understanding of the present invention. However, it is obvious to those of ordinary skill in the art that these specific details are not necessary to practice the present invention. In other examples, in order to avoid confusing the present invention, well-known technologies, such as specific construction details, operating conditions and other technical conditions, are not specifically described.

[0153] The principles and implementation methods of the present invention are described in this article using specific examples. The description of the above embodiments is only used to help understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A soil heavy metal pollution ecological risk assessment method, characterized in that: The following steps are involved: S1. Collect mixed samples of topsoil from the plots that require ecological risk assessment, and analyze and determine the heavy metal elements in the mixed samples of topsoil according to the "Technical Regulations on Soil Sample Analysis and Testing Methods for National Soil Pollution Status Detailed Investigation"; S2, for the heavy metal elements analyzed and determined in S1, obtain the 10% inhibitory effect concentration EC of different heavy metal elements on barley 10 , and for EC 10 Standardize the process; S3, based on the normalized EC 10 The ecological risk reference value is calculated, and the risk quotient of each heavy metal element is added up to obtain the total risk quotient of the surface soil mixed sample; And carry out ecological risk assessment on the mixed surface soil sample according to the total risk quotient.

2. The method for ecological risk assessment of soil heavy metal pollution according to claim 1, characterized in that: The calculation formula of the total risk quotient in S3 is: Among them, C D,i is the content of heavy metals in soil, EC 10 The standardized EC values ​​of different heavy metals on barley root elongation 10 Geometric mean. If there are multiple geometric means for the same heavy metal element, the average of these ensemble means is used. RQ4 is the standardized EC 10 The total risk quotient calculated for the ecological risk reference value.

3. The method for ecological risk assessment of soil heavy metal pollution according to claim 1, characterized in that: The method further comprises: When the 5% Hazard Concentration HC5 of some heavy metal elements is difficult to obtain, the risk quotient calculated based on barley EC 10 will be multiplied by 4, and according to the type N of heavy metal elements, it will be defined as slight risk, medium risk, strong risk, and extremely strong risk levels as N, (1 - 2)N, (2 - 4)N, and >4N respectively.

4. The method for ecological risk assessment of soil heavy metal pollution according to claim 1, characterized in that: The S3, normalized to the EC 10 is the ecological risk reference value, the risk quotient of each heavy metal element is calculated, and the risk quotients of each heavy metal element are added to obtain the total risk quotient of the surface soil mixed sample; and the ecological risk assessment of the surface soil mixed sample is performed according to the total risk quotient, which can be replaced by: Obtain literature on soil heavy metal ecotoxicology research, screen and organize the data in the literature, and obtain the 5% hazardous concentration HC5 of some heavy metal elements; Using the risk screening value under non-paddy field conditions or the risk screening value under paddy field conditions or HC5 as the toxicity threshold, and calculating the risk quotient corresponding to the toxicity threshold; An ecological risk assessment is performed based on the risk quotient corresponding to the toxicity threshold.

5. The method for ecological risk assessment of soil heavy metal pollution according to claim 1, characterized in that: The S3, normalized to the EC 10 is the ecological risk reference value, the risk quotient of each heavy metal element is calculated, and the risk quotients of each heavy metal element are added to obtain the total risk quotient of the surface soil mixed sample; the ecological risk assessment of the surface soil mixed sample is performed according to the total risk quotient, which can be replaced by: Taking the soil background value as the reference value, calculate the potential ecological risk assessment index value RI1 corresponding to each heavy metal element in the surface soil mixed sample, and conduct ecological risk assessment based on RI1: Alternatively, the risk screening value is used as a reference value to calculate the potential ecological risk assessment index value RI2 corresponding to each heavy metal element in the surface soil mixed sample, and the ecological risk assessment is performed based on RI2: Where n is the number of metals; RI i is the potential ecological risk assessment index of a single metal; T r,i is the toxicity coefficient of heavy metals, among which the toxicity coefficients of Cd, Ni, Pb, Cu, and Zn are 30, 5, 5, 5, and 1 respectively; C D,i is the measured soil heavy metal content; RS i The risk screening value of agricultural land soil pollution under non-paddy field conditions in the Soil Environmental Quality Agricultural Land Soil Pollution Risk Control Standard (Trial) is used; Cu adopts the risk screening value of agricultural land soil pollution under non-orchard conditions; C R,i is the background value of soil heavy metals, among which the soil heavy metal background paper values ​​of Cd, Ni, Pb, Cu and Zn are 0.14, 12.4, 45.8, 14.8 and 63 respectively.

6. The method for ecological risk assessment of soil heavy metal pollution according to claim 4, characterized in that: The risk screening value under non-paddy field conditions or the risk screening value under paddy field conditions or HC5 or EC 10 As the toxicity threshold, the risk quotient corresponding to the toxicity threshold is calculated, specifically including: Taking the risk screening value under non-paddy field conditions as the ecological risk reference value, the risk quotient RQ1 is calculated: Taking the risk screening value under paddy field conditions as the ecological risk reference value, the risk quotient RQ2 is calculated: Taking HC5 as the ecological risk reference value, calculate the risk quotient RQ3: Where: n is the amount of heavy metals; RQ i is the risk quotient of a single heavy metal, i is 1, 2, 3, 4; C D,i is the content of heavy metals in soil; RS 1i , RS 2i They are the agricultural land soil pollution risk screening values ​​under non-paddy field conditions and paddy field conditions in the Soil Environmental Quality Agricultural Land Soil Pollution Risk Control Standard (Trial) respectively; HC5 is the geometric mean of HC5 of different heavy metal elements sorted out.

7. The method for ecological risk assessment of soil heavy metal pollution according to claim 1, characterized in that: In S1, the heavy metals in the soil samples are analyzed and measured according to the "Technical Regulations on Analysis and Testing Methods for Soil Samples in the National Soil Pollution Status Detailed Investigation", specifically including: Soil samples with different degrees of contamination were collected around the contaminated site. The soil samples at each sampling point were air-dried to remove impurities, crushed and sieved, and the soil physical and chemical properties, soil pH value, soil organic matter content, and cation exchange capacity were measured. Heavy metal elements were determined using flame atomic absorption spectrometry.

8. A soil heavy metal pollution ecological risk assessment system, applied to the soil heavy metal pollution ecological risk assessment method according to any one of claims 1 to 7, characterized in that: include: The element determination module is used to collect mixed samples of topsoil in the plots that require ecological risk assessment, and analyze and determine the heavy metal elements in the mixed samples of topsoil according to the "Technical Regulations on Analysis and Testing Methods of Soil Samples for National Soil Pollution Status Detailed Investigation"; Standardization module, used for analyzing and determining the heavy metal elements in the S1, and obtaining the 10% inhibitory effect concentration EC of different heavy metal elements on barley 10 , and for EC 10 Standardize the process; Evaluation module for standardized EC 10 The ecological risk reference value is calculated, and the risk quotient of each heavy metal element is added up to obtain the total risk quotient of the surface soil mixed sample; And carry out ecological risk assessment on the mixed surface soil sample according to the total risk quotient.

Images