Construction method and application of marine micro-plastic ecological risk assessment model based on multilevel toxicity effect

Abstract

The invention relates to a construction method and application of a marine micro-plastic ecological risk assessment model based on a multilevel toxicity effect, and belongs to the technical field of ecological risk assessment of marine pollutants. According to the method, a toxicity end point sensitive to exposure of the microplastics is determined by screening research results of the microplastics on toxicity effects of marine organisms at different levels, and non-effect concentration is deduced and predicted by adopting a species sensitivity distribution model. The ecological risk of micro-plastic pollution in the marine water environment is determined according to the environmental concentration of the micro-plastic and the PNEC of the micro-plastic to marine organisms. According to the method, the ecological risk of the micro-plastics is evaluated from multiple levels, and the ecological risk of the micro-plastics to marine organisms can be pre-judged in advance. When it is detected that the microplastic with pathological damage, oxidative stress, metabolic toxicity and genotoxicity is in a high-risk state, intervention needs to be performed in advance to prevent the risk from being further expanded to affect individuals and populations of marine organisms.

Description

Technical Field

[0001] The present invention belongs to the technical field of ecological risk assessment of marine pollutants, and particularly relates to a method for constructing and applying an ecological risk assessment model of marine microplastics based on multi-level toxicity effects. Background Art

[0002] Microplastics (<5 mm) are a class of new pollutants that have attracted extensive international attention. Microplastic pollution is widespread in the global ocean, and microplastics have been found in marine surveys from the coast to the open ocean, from the equator to the poles, and from surface seawater to deep-sea sediments. Due to their small particle size, microplastics are easily ingested by marine organisms and transferred to higher trophic levels through the food chain. Microplastics can also release toxic chemicals or adsorb more environmental pollutants, posing a serious threat to marine organisms as a pollutant carrier.

[0003] Microplastic pollution has had an ecological impact on marine organisms. However, at present, there is little research on the ecological risk of microplastics to marine organisms in the real environment, and the few existing studies are based on the survival, death, reproduction, etc. of individual or population of aquatic organisms caused by microplastics. In most cases, these individual-level indicators are mostly at the mg / L level, much higher than the environmental pollution level of microplastics, and are even less able to provide early warning and rapid response to the damage of microplastics to organisms. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a method for constructing and applying an ecological risk assessment model of marine microplastics based on multi-level toxicity effects, which can more accurately and objectively evaluate the ecological hazards caused by microplastic pollution.

[0005] The principle of the present invention: Screening the research results of the multi-level toxicity effects of microplastics on marine organisms to determine the toxicity endpoints sensitive to microplastic exposure, using the Species Sensitivity Distribution (SSD) model to derive and predict the Predicted No Effect Concentration (PNEC), and determining the ecological risk of microplastic pollution in the marine water environment based on the Environmental Concentration (EC) of microplastics and their PNEC for marine organisms.

[0006] The present invention is realized by the following technical solutions:

[0007] A method for constructing an ecological risk assessment model of marine microplastics based on multi-level toxicity effects, the method comprising the following steps:

[0008] Step 1: Screen representative biological species of the target marine ecosystem. The selected biological groups must include different biological groups such as microalgae, arthropods, shellfish, and fish, and the biological species meet more than 8 species in 5 families of 3 phyla;

[0009] Step 2: Obtain toxicity data of microplastics on marine organisms at different levels including population, individual, organ, cell, physiology, and gene;

[0010] Step 3: The toxicity data described in Step 2 includes acute and chronic toxicity data, including toxicity concentrations such as LC 50 , EC 50 , LOEC, and NOEC. Normalize and convert the collected toxicity data through an assessment factor;

[0011] Step 4: Use the data after normalization in Step 3 and construct an ecological model through the SSD method to determine the concentration corresponding to the fifth percentile of SSD (HC5), that is, determine the pollutant concentration protecting 95% of the species, and deduce PNEC by extrapolation;

[0012] Step 5: Compare the sensitivities of different-level toxicity endpoints to microplastic exposure, and screen out the toxicity endpoints most sensitive to microplastic pollution;

[0013] Step 6: Adopt the risk quotient method to calculate the ratio of microplastic EC to PNEC, which is the ecological risk value of microplastic pollution in the target sea area;

[0014]

[0015] And give the risk level through the following judgment;

[0016] When RQ < 0.01, it indicates that there is no risk of microplastic pollution in the target sea area;

[0017] When 0.01 ≤ RQ < 0.1, it indicates that the ecological risk of microplastic pollution in the target sea area is low risk;

[0018] When 0.1 ≤ RQ < 1.0, it indicates that the ecological risk of microplastic pollution in the target sea area is medium risk;

[0019] When RQ ≥ 1.0, it indicates that the ecological risk of microplastic pollution in the target sea area is high risk;

[0020] Step 7: Adopt the potential impact proportion method, and the cumulative probability directly obtained based on the position of the microplastic pollution concentration on the SSD curve is the proportion of species affected at the target station (Potential affect fraction, PAF);

[0021]

[0022] Wherein, a and b are model parameters.

[0023] The present invention also provides a method for evaluating the ecological risk of marine microplastics using the constructed model, and the method is as follows:

[0024] Step 1: Representative sampling stations are arranged in the target sea area to collect water samples. The microplastics in the samples are separated, extracted, observed and identified to determine the quantity, size, shape and composition characteristics of microplastics in the seawater samples.

[0025] Step 2: According to the quantity, size, shape and composition characteristics of microplastics, the number concentration of microplastics is converted into mass concentration. The mass concentration of microplastics is the product of the number concentration of microplastics and its density and volume.

[0026] Step 3: Input the mass concentration obtained in Step 2 into the model to obtain the ratio of EC to PNEC, which is the ecological risk value of microplastic pollution in the target sea area, and obtain the risk level.

[0027] Step 4: Based on the position of the microplastic mass concentration on the SSD curve, the cumulative probability directly obtained is the proportion of species affected at the target station.

[0028] The beneficial effects of the present invention compared with the prior art: The present invention evaluates the ecological risk of microplastics at multiple levels, not only from the individual and community levels, but also from pathological damage, oxidative stress, metabolic toxicity and genotoxicity, and can predict in advance the ecological risk of microplastics to marine organisms. When it is detected that the pathological damage, oxidative stress, metabolic toxicity and genotoxicity of microplastics are in a high-risk state, intervention should be carried out in advance to prevent the risk from further expanding and affecting the individuals and populations of marine organisms. Description of the Drawings

[0029] Figure 1 Ecological risk assessment model diagram of marine microplastics based on multi-level toxicity effects;

[0030] Figure 2 Ecological risk map of microplastic pollution at different stations in the northern Yellow Sea based on multi-level toxicity effects;

[0031] Figure 3 Diagram of the proportion of biological species affected by microplastic pollution at different stations in the northern Yellow Sea based on multi-level toxicity effects. Detailed Embodiments

[0032] The technical solutions of the present invention will be further explained below through examples, but the protection scope of the present invention is not limited by any form of the examples.

[0033] Example 1

[0034] A construction method of an ecological risk model for microplastics in the surface water of the northern Yellow Sea based on multi-level toxicity effects, the method comprising the following steps:

[0035] (1) Screening representative biological species with the characteristics of the biological flora in the Yellow Sea area, and the selected biological groups must include different marine biological groups such as microalgae, arthropods, shellfish and fish, and more than 8 species in 5 families of 3 phyla are selected; As a specific implementation method, the selected representative organisms are shown in Tables 1 to 5;

[0036] (2) Obtaining the toxicity endpoints of microplastics at different levels of marine organisms. As a specific implementation method, growth and survival, histopathology, oxidative stress, metabolic toxicity and genotoxicity are selected;

[0037] (3) The toxicity data includes acute and chronic toxicity data, including LC 50 , EC 50 , LOEC and NOEC and other toxicity concentrations. As a specific implementation method, the selected toxicity data are shown in Tables 1 to 5; The collected toxicity data is converted into NOEC through the assessment factors AF time and AF effect . For acute toxicity data, AF time = 10, for chronic toxicity data, AF time = 1, for LC 50 and EC 50 , AF effect = 10, for LOEC, AF effect = 2, for NOEC, AF effect = 1;

[0038] Table 1 Individual-population level toxicity data

[0039]

[0040] Table 2 Histopathological injury toxicity data

[0041]

[0042] Table 3 Oxidative stress toxicity data

[0043]

[0044] Table 4 Metabolic toxicity data

[0045]

[0046] Table 5 Genotoxicity data

[0047]

[0048] (4) Fit the SSD curve using the normal distribution model to determine HC5, and derive PNEC by extrapolation method;

[0049] Arrange the toxicity values of the species in ascending order, assign ranks to them, and calculate the cumulative probability of each species according to the following formula:

[0050]

[0051] In the formula, P is the cumulative probability (%), R is the rank of the species in the ranking, and N is the number of species.

[0052] Then establish a coordinate system with concentration and cumulative probability as the X-axis and Y-axis respectively, and mark these data points according to the toxicity values and cumulative probabilities of different organisms. Finally, select the normal distribution to fit the distribution of these data points to obtain the SSD curve of the toxicity effects of microplastics on different levels of marine organisms.

[0053] Calculate the species hazard concentration with a cumulative frequency of 5%, which is HC5. In this study, the statistical extrapolation method is used to calculate the ecological safety threshold PNEC. Since it has been converted according to the assessment factors, HC5 is extracted as PNEC, as shown in Table 6;

[0054] Table 6 Predicted no-effect concentration PNEC (μg / L) of toxicity effects at different levels

[0055]

[0056] (5) Comparison of sensitivities of different levels of toxicity endpoints to microplastic exposure:

[0057] Use the two-sample K-S test to compare the differences between the SSDs of different toxicological endpoints of microplastics. When the difference in HC5 of different level indicators is within 2 times, it is considered no difference; when it is within one order of magnitude, there is a certain difference; when it exceeds one order of magnitude, there is a large difference. The toxicity endpoints most sensitive to microplastic pollution are screened out as follows: oxidative stress > metabolic toxicity > genotoxicity = pathological damage > individual-population toxicity;

[0058] (7) Set up representative sampling stations in the surface water of the northern Yellow Sea, separate, extract, observe and identify the microplastics in the samples to determine the quantity, size, shape and composition characteristics of the microplastics in the seawater samples;

[0059] (8) According to the quantity, size, shape and composition characteristics of the microplastics, convert the number concentration of the microplastics into mass concentration;

[0060] For spherical or irregularly shaped microplastics:

[0061]

[0062] For fibrous microplastics:

[0063] C mass = C number ·ρ·πγ 2 ·l

[0064] Where: ρ—the polymer density of microplastics, obtained from the polymer density database (http: / / polymerdatabase.com / );

[0065] r—the radius of spherical and irregular microplastics;

[0066] l—the length of fibrous microplastics.

[0067]

[0068] (9) Using the risk quotient method, calculate the ratio of microplastic EC to PNEC, which is the ecological risk value of microplastic pollution in the northern Yellow Sea, Figure 2 and give the risk values of microplastic pollution at different stations in the northern Yellow Sea based on different levels of toxic effects;

[0069]

[0070] (10) Using the potential impact fraction method, calculate the cumulative probability corresponding to the microplastic pollution concentration at different sampling stations in the northern Yellow Sea on the SSD curve, which is the species PAF; Figure 3 and give the potential impact fractions of microplastic pollution at different stations in the northern Yellow Sea based on different levels of toxic effects;

[0071]

[0072] (11) Assessment conclusion: The ecological risk of microplastic pollution in the northern Yellow Sea based on multi-level toxic effects ranges from low risk to high risk. This method is more sensitive than traditional ecological risk assessment methods established at the individual or population level of microplastics, which is conducive to early warning and rapid response to the damage of microplastics to organisms.

Claims

1. A method for constructing an ecological risk assessment model of marine microplastics based on multi-level toxicity effects, characterized in that, The method includes the following steps: Step 1: Screen representative biological species of the target marine ecosystem. The selected biological groups must include different biological groups such as microalgae, arthropods, shellfish, and fish, and the biological species meet more than 8 species in 5 families of 3 phyla; Step 2: Obtain toxicity data of microplastics on marine organisms at different levels including population, individual, organ, cell, physiology, and gene; Step 3. The toxicity data described in Step 2 includes acute and chronic toxicity data, including toxicity concentrations such as LC 50 , EC 50 , LOEC and NOEC. Normalize the collected toxicity data through the assessment factor; Step 4: Use the data after normalization in Step 3 and construct an ecological model through the SSD method to determine the concentration HC5 corresponding to the fifth percentile of SSD, that is, determine the pollutant concentration protecting 95% of the species, and derive the predicted no-effect concentration PNEC by extrapolation of the model; Step 5: Compare the sensitivities of different-level toxicity endpoints to microplastic exposure and screen out the toxicity endpoint most sensitive to microplastic pollution; Step 6: Adopt the risk quotient method to calculate the ratio of the environmental concentration EC of microplastics to the predicted no-effect concentration PNEC derived from the model, which is the ecological risk value RQ of microplastic pollution in the target sea area; And give the risk level through the following judgment; When RQ < 0.01, it indicates that there is no risk of microplastic pollution in the target sea area; When 0.01 ≤ RQ < 0.1, it indicates that the ecological risk of microplastic pollution in the target sea area is low risk; When 0.1 ≤ RQ < 1.0, it indicates that the ecological risk of microplastic pollution in the target sea area is medium risk; When RQ ≥ 1.0, it indicates that the ecological risk of microplastic pollution in the target sea area is high risk; Step 7: Adopt the potential impact fraction method, and the cumulative probability directly obtained based on the position of the microplastic pollution concentration on the SSD curve is the proportion of affected species PAF at the target station; In the formula, a and b are model parameters.

2. A method for evaluating the marine ecological risk using the model constructed by the method according to claim 1, characterized in that The method is as follows: Step 1: Arrange representative sampling stations in the target sea area to collect water samples, separate, extract, observe, and identify and analyze the samples to determine the quantity, size, shape, and composition characteristics of microplastics in the seawater samples; Step 2: Convert the number concentration of microplastics into mass concentration according to the quantity, size, shape, and composition characteristics of microplastics; Step 3: Input the mass concentration obtained in Step 2 into the model to obtain the ratio of EC to PNEC, which is the ecological risk value of microplastic pollution in the target sea area, and obtain the risk level; Step 4: Based on the position of the microplastic mass concentration on the SSD curve, the directly obtained cumulative probability is the proportion of affected species PAF at the target station.

3. The method according to claim 2, wherein The mass concentration of microplastics is the product of the number concentration of microplastics and its density and volume.

Images