Microalgae model-based multi-index organophosphorus pesticide ecological risk assessment method

Abstract

The invention discloses a multi-index organophosphorus pesticide ecological risk evaluation method based on a microalgae model. The method comprises physiological and biochemical influence evaluation, algal bloom outbreak risk evaluation, algal toxin synthesis and release influence evaluation and water algal toxin ecological risk influence evaluation. According to the evaluation method, by constructing a multi-index joint evaluation system based on the microalgae model, early interference signals of organophosphorus pesticides on an ecological system can be captured from multiple dimensions, and the limitation of traditional single-index evaluation is overcome; according to the evaluation method disclosed by the invention, macroscopic and microscopic processes of the microalgae in the water body are considered, the action mechanisms of the organophosphorus pesticide on blue-green algae growth, algal toxin synthesis and release and the like are included, the environmental risk of microalgae metabolites is considered, and the ecological risk of the organophosphorus pesticide in the water body can be systematically and comprehensively evaluated; the evaluation method provided by the invention can provide powerful theoretical basis and support for behavior research and use management of the organophosphorus pesticide in the water environment.

Description

Technical Field

[0001] The invention belongs to the technical field of environmental risk assessment, and in particular relates to a multi-index method for assessing the ecological risk of organophosphorus pesticides based on a microalgae model. Background Art

[0002] During use, organophosphorus pesticides enter water bodies, soil and other ecosystems through surface runoff, atmospheric deposition and soil infiltration. In the aquatic environment, they will cause direct or indirect harm to aquatic organisms, from plankton to higher organisms such as fish, and the entire aquatic ecological food chain is threatened.

[0003] Existing methods for evaluating the ecological risk of organophosphorus pesticides often focus on a single indicator or toxicity tests on a few organisms. For example, they only focus on the acute mortality rate of organophosphorus to fish, or use the growth inhibition of a single aquatic invertebrate as the criterion. However, ecosystems are highly complex, and a single indicator cannot fully reflect the comprehensive impact of pesticides on the entire ecosystem. Different organisms have different sensitivities to organophosphorus pesticides, and it is difficult to accurately measure the potential hazards of pesticides in the actual environment by relying solely on the responses of individual species. To this end, it is very necessary to develop a multi-indicator method for evaluating the ecological risk of organophosphorus pesticides based on a microalgae model that can solve the above problems. Summary of the invention

[0004] In order to solve the above technical problems, the purpose of the present invention is to provide a multi-index method for evaluating the ecological risk of organophosphorus pesticides based on a microalgae model; microalgae, as primary producers in aquatic ecosystems, play a fundamental role in material circulation and energy flow. They are extremely sensitive to environmental changes and can quickly respond to the pollution stress of organophosphorus pesticides in water bodies; the present invention can capture the early interference signals of organophosphorus pesticides on the ecosystem from multiple dimensions by constructing a multi-index joint evaluation system based on a microalgae model, overcome the limitations of traditional single-index evaluation, and provide strong support for more accurate and comprehensive evaluation of the ecological risks of organophosphorus pesticides, which is of great practical significance for maintaining ecological balance and ensuring sustainable agricultural development.

[0005] The object of the present invention is achieved by comprising: (1) Physiological and biochemical impact assessment: By measuring algae density, photosynthetic activity, metabolic activity, oxidative stress, and cell membrane integrity, the macroscopic and microscopic effects of organophosphorus pesticides on cyanobacteria in water bodies are assessed, including: (101) Growth evaluation: At different time points during the cyanobacteria cultivation, the density of cyanobacteria cultured with different concentrations of organophosphorus pesticides was measured, the inhibition rate of organophosphorus pesticides at different concentrations on cyanobacteria was calculated, and the effects of organophosphorus pesticides at different concentrations on the growth of cyanobacteria were evaluated; For algae density determination, absorbance method, cell counter, blood cell counting plate counting method and flow cytometer can be used for determination. Low-light method requires the establishment of a standard curve of algae absorbance at 680nm and algae density. However, when algae cells grow to the plateau stage and the decline stage, the cell damage may affect its accuracy. The cell counter cannot distinguish between intact cells and damaged cells. The blood cell counting plate has a large workload and many error factors. Therefore, it is recommended to use flow cytometer to determine algae density. (102) Evaluation of photosynthetic activity: Take the cyanobacteria cultured with different concentrations of organophosphorus pesticides, separate the algal cells by centrifugation, and then use 95% ethanol to extract chlorophyll a at 80°C (water bath) in the dark for 1 hour. Measure the absorbance of the supernatant at 649 and 665 nm to determine the chlorophyll a, and calculate the chlorophyll a content of the extract to evaluate the effects of different concentrations of organophosphorus pesticides on the photosynthesis of cyanobacteria; The photosynthetic activity of algae cells was analyzed by measuring the chlorophyll content. The algae cells were separated by centrifugation, and then chlorophyll a was extracted with 95% ethanol at 80°C (water bath) in the dark for 1 hour; then the absorbance of the supernatant was measured at 649 and 665nm using a UV-visible spectrophotometer to determine chlorophyll a, and then the chlorophyll a content (μg / L) of the extract was calculated using the following formula; note that different methods correspond to different calculation formulas, and you can also refer to published literature; ; (103) Metabolic activity evaluation: Take the cyanobacteria liquid cultured with different concentrations of organophosphorus pesticides, centrifuge to obtain cyanobacterial cells, add ATP extract, freeze the cells in liquid nitrogen, thaw at ambient temperature and repeat the cycle, calculate the ATP content under different concentrations of organophosphorus pesticides, and evaluate the effects of different concentrations of organophosphorus pesticides on the metabolic activity of cyanobacteria; ATP is determined by a kit, and the specific determination is carried out according to the instructions of the kit; (104) Oxidative stress assessment: Take the cyanobacteria cultured with different concentrations of organophosphorus pesticides, centrifuge to obtain cyanobacterial cells, measure reactive oxygen species (ROS), superoxide dismutase (SOD), and reduced glutathione (GSH), and evaluate the effects of different concentrations of organophosphorus pesticides on oxidative stress of cyanobacteria; all indicators can be measured by purchasing corresponding kits according to the kit instructions; (105) Cell membrane integrity: Take cyanobacteria cultured with different concentrations of organophosphorus pesticides, measure the permeability of cyanobacterial cell membranes, and evaluate the effects of different concentrations of organophosphorus pesticides on the integrity of cyanobacterial cell membranes. The membrane permeability can be measured using SYTOX Green nucleic acid fluorescent dye, and it is recommended to use flow cytometry for measurement. (2) Algal bloom risk assessment: Use the logistic model to analyze the data on the change of algal density over time at each organophosphorus pesticide concentration and obtain the maximum population density corresponding to each concentration. K , the relative position a of the curve to the origin, the value of the intrinsic growth rate r of the population, and then calculate the maximum growth rate R of the population max , the formula is: Where N is the population density at time t, mL -1 ; t is the culture time, d; K is the maximum population density, mL -1 ; a is a constant, indicating the relative position of the curve to the origin; r is the intrinsic growth rate of the population, d -1 ; R is the maximum growth rate of the population, mL -1 ·d -1 ; By comparison K Value and R max The value of the effect of organophosphorus pesticides on the growth of cyanobacteria was evaluated. K Value and R max The larger the value, the higher the risk of algal bloom outbreak; The time it takes for the exposure group and the control group to reach the same bloom level and the final cyanobacteria bloom level can also be compared to evaluate the effects of organophosphorus pesticides on the outbreak time and level of cyanobacteria bloom in water bodies. (3) Evaluation of the impact of algal toxin synthesis and release: Take the cyanobacterial liquid cultured with different concentrations of organophosphorus pesticides, break the algal cells (freeze-thaw method or ultrasonic method can be used. If freeze-thaw method is used, the breaking effect must be tested first to ensure accuracy. Ultrasonic method is recommended to break the algal cells) to release algal toxins. After centrifugation, measure the algal toxin concentration in the supernatant. The concentration of algal toxins can be determined using the corresponding kit to evaluate the effects of different concentrations of organophosphorus pesticides on the synthesis and release of algal toxins in cyanobacterial cells; (4) Assessment of ecological risk impact of algae toxins in water bodies: The risk entropy method is used. Specifically, ecological receptors are selected and the peak concentrations of algae toxins in the culture system of organophosphorus pesticides at different concentrations are compared with the toxic endpoint value EC50 measured in the laboratory to characterize the hazard of algae toxins. The risk quotient RQ is obtained. When RQ>1, it is a high risk; when 0.1≤RQ<1, it is a medium risk; when 0.0.1≤RQ<0.1, it is a low risk. In this way, a preliminary judgment on the ecological risk of organophosphorus pesticides is made. The calculation formula is as follows: Wherein, MEC is the mass concentration measured in the environment, ng / L; PNEC is the expected no-effect mass concentration, ng / L; AF is the assessment factor used to select acute toxicity data, which is 1000; Among them, it is necessary to determine the selection of ecological receptors. It is recommended to select more representative aquatic species as ecological receptors. The biological toxicity endpoint value EC50 can be obtained through self-experiments or from the US ECOTOX database.

[0006] Preferably, the cyanobacteria is Microcystis aeruginosa.

[0007] Preferably, the cultivation of different concentrations of organophosphorus pesticides is specifically: the initial algae density is 1.0×10 6 cells / mL-1.5×10 6 cells / mL of cyanobacteria were exposed to a culture medium containing different concentrations of organophosphorus pesticides. The culture medium was 250mL of BG11 medium. The culture conditions were: temperature 25±1℃, light intensity 2000lx, light-dark ratio 12h:12h, humidity 50%, and continuous shaking at 120rpm.

[0008] Preferably, the organophosphorus pesticides of different concentrations are set in multiple groups within the actual water concentration range according to the concentration change trend, including a blank control group and the concentration changes of the target organophosphorus pesticide during accumulation, degradation and transformation in the water body.

[0009] Compared with the prior art, the present invention has the following technical effects: 1. The evaluation method of the present invention can capture the early interference signals of organophosphorus pesticides on the ecosystem from multiple dimensions by constructing a multi-index joint evaluation system based on a microalgae model, thus overcoming the limitations of traditional single-index evaluation; 2. The evaluation method of the present invention takes into account both the macroscopic and microscopic processes of microalgae in water bodies, encompasses the mechanism of action of organophosphorus pesticides on the growth of cyanobacteria, the synthesis and release of algal toxins, and considers the environmental risks of microalgae metabolites. It can systematically and comprehensively evaluate the ecological risks of organophosphorus pesticides in water bodies; the evaluation method of the present invention can provide a strong theoretical basis and support for the behavior research and use management of organophosphorus pesticides in water environments; 3. The present invention establishes an evaluation method based on the effects of organophosphorus pesticides at different concentrations on the growth of cyanobacteria and the production of algal toxins, which will supplement the understanding of the interaction between cyanobacteria and organophosphorus pesticides in water. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 The algae density (A) and growth promotion rate (B) of Microcystis aeruginosa exposed to different concentrations of trichlorfon in Example 1; Figure 2 The chlorophyll a (A) and ATP (B) contents of Microcystis aeruginosa exposed to different concentrations of trichlorfon in Example 1; Figure 3The results of measuring the oxidative stress indexes of Microcystis aeruginosa under exposure to different concentrations of trichlorfon in Example 1, (A) is ROS, (B) is SOD, and (C) is GSH; Figure 4 The cell membrane integrity of Microcystis aeruginosa exposed to different concentrations of trichlorfon in Example 1; Figure 5 is the maximum biomass of Microcystis aeruginosa under exposure to different concentrations of trichlorfon in Example 1 ( K ) and the maximum growth rate (R max ); Figure 6 The content of algal toxin per unit cell of Microcystis aeruginosa under exposure to different concentrations of trichlorfon in Example 1; Figure 7 The ecological risks of water bodies exposed to different concentrations of trichlorfon in Example 1. DETAILED DESCRIPTION

[0011] The present invention is further described below in conjunction with the accompanying drawings, but the present invention is not limited in any way. Any changes or substitutions made based on the teachings of the present invention belong to the protection scope of the present invention.

[0012] Example 1 Ecological risk assessment of organophosphorus pesticide trichlorfon in water bodies. The cyanobacteria used in this example are Microcystis aeruginosa (FACHB905) purchased from the Freshwater Algae Seed Bank of the Chinese Academy of Sciences; The specific cultivation of different concentrations of organophosphorus pesticides is as follows: the initial algae density is 1.0×10 6 cells / mL-1.5×10 6 cells / mL of cyanobacteria were exposed to a culture medium containing different concentrations of organophosphorus pesticides, the culture medium was 250mL of BG11 culture medium, the culture conditions were: temperature 25±1℃, light intensity 2000lx, light-dark ratio 12h:12h, humidity 50%, and continuous shaking at a speed of 120rpm; considering the concentration change trend within the concentration range of the water body, 0mg / L, 0.00001mg / L, 0.0001mg / L, 0.001mg / L, 0.01mg / L, 0.1mg / L, 1mg / L, 10mg / L, and 100mg / L of trichlorfon solution were set, and the concentration design took into account the actual concentration of trichlorfon in water and the impact addition; The multi-index method for evaluating the ecological risk of organophosphorus pesticides based on the microalgae model in this embodiment includes: (1) Physiological and biochemical impact assessment: (101) Growth evaluation: On the 0th, 1st, 3rd, 5th, 7th, 9th, 11th, 13th, 15th, 17th and 19th days of cyanobacteria cultivation, the densities of cyanobacteria under different concentrations of organophosphorus pesticides were measured, and a standard curve of absorbance and algae density was established: y = 12.5x + 0.206 (R 2 =0.99), where x is the absorbance at 680 nm (dimensionless), and y is the algae density measured by the cell counter (10 6 cells / mL); after each sampling, the absorbance at 680nm was measured by UV-visible spectrometer, and the algae density of the sample was calculated by the standard curve. The results are as follows Figure 1 As shown, from Figure 1 In A, it can be seen that compared with the control group (0 mg / L), trichlorfon <100 mg / L enhanced the growth of microalgae, while trichlorfon 100 mg / L inhibited the growth of Microcystis aeruginosa; Figure 1 B shows that when the concentration of trichlorfon is 0.01 mg / L, the cell density increases to 127.8% of the control group, while the inhibition rate of 100 mg / L trichlorfon on Microcystis aeruginosa cells is 44.2%, indicating that the promotion effect of trichlorfon on Microcystis aeruginosa becomes more obvious with the increase of trichlorfon concentration (0.00001-0.01 mg / L); this shows that low concentration of trichlorfon in water can promote the growth of Microcystis aeruginosa, and as trichlorfon continues to enter the water body, this promotion effect will increase, which may increase the risk of blue algae blooms in the water body; (102) Photosynthetic activity evaluation: Take the cyanobacteria liquid cultured with different concentrations of organophosphorus pesticides (cultured for 9 days (logarithmic growth period), 2 mL of liquid), centrifuge (10000 rpm, 10 min, 4°C), pour out the supernatant, add 2 mL of 80°C 95% ethanol, and water bath at 80°C for 1 h. Use 95% ethanol as a reference to measure the OD649 and OD665 of the supernatant, and then calculate (μg / L) according to the formula. The results are as follows: Figure 2 As shown in A, it can be seen from the figure that as the concentration of trichlorfon increases from 0.00001 to 0.01 mg / L, the concentration of chlorophyll a increases from 16.9×10 -8 mg / L increased to 18.23×10 -8 mg / L, chlorophyll a is an important component of the photosynthesis process, so low concentrations of trichlorfon can improve photosynthesis efficiency, and gradually enhance the ability to promote photosynthesis with the increase of trichlorfon concentration. The trend of trichlorfon promoting chlorophyll a is consistent with the trend of promoting algae growth, indicating that the increase of chlorophyll a may be one of the factors promoting the growth of Microcystis aeruginosa, while high concentrations of trichlorfon inhibit photosynthesis, thereby inhibiting the growth of Microcystis aeruginosa. The chlorophyll content is calculated according to the following formula: ; (103) Metabolic activity assessment: Cyanobacterial liquid cultured with different concentrations of organophosphorus pesticides (cultured for 9 days (logarithmic growth phase), 2 mL of liquid) was centrifuged (10,000 rpm, 10 min, 4°C) to obtain cyanobacterial cells (5 million to 20 million). ATP extract was added, the cells were frozen in liquid nitrogen, thawed at ambient temperature and repeated three cycles. ATP was determined according to the manufacturer's recommendations (Greis Biotech, China). The results are shown in Table 1. Figure 2 As shown in Figure B, it can be seen from the figure that when the concentration of trichlorfon is 0.01 mg / L, the ATP content is 1.83 times that of the control group; when it is 100 mg / L, ATP is 87.28% of the control group; ATP is the basic carrier of energy conversion in organisms and the most direct energy source in organisms. The increase in ATP indicates that low concentrations of trichlorfon enhance the metabolic activity of Microcystis aeruginosa; these changes verify the growth trend of Microcystis aeruginosa under low concentrations of trichlorfon; (104) Oxidative stress assessment: Take the cyanobacterial liquid cultured with different concentrations of organophosphorus pesticides (cultured for 9 days (logarithmic growth phase), 2 mL of liquid), centrifuge (10000 rpm, 10 min, 4°C) to obtain cyanobacterial cells (5 million to 20 million), add 1 mL of DCFH-DA probe with an initial concentration of 10 μM, incubate at 37°C in the dark for 30 min, centrifuge (10000 rpm, 10 min, 4°C), remove the supernatant, wash twice with 1 mL of phosphate buffered saline (PBS), and then add 1 mL Resuspend in PBS; take 0.2 mL of the resuspended algae solution into a 96-well plate, and measure the fluorescence intensity of Ex / Em: 465 / 525 nm with a microplate reader to determine ROS; obtain a certain number (5 million to 20 million) of algae cells by centrifugation (10000 rpm, 10 min, 4°C), and then add SOD and GSH extracts; freeze the cells in liquid nitrogen, thaw at ambient temperature and repeat three cycles; then, determine SOD and GSH according to the recommendations of the kit manufacturer (Greis Biotech, China), and the results are shown in the figure. Figure 3 As shown, from Figure 3 It can be seen that exposure to trichlorfon caused a significant increase in ROS, which is a common byproduct of oxidative metabolism. SOD and GSH are important components of the antioxidant system, which increase and decrease due to oxidative stress, respectively; these results indicate that low concentrations of trichlorfon cause mild oxidative stress in Microcystis aeruginosa cells; (105) Cell membrane integrity: Take the cyanobacteria cultured with different concentrations of organophosphorus pesticides (cultured for 9 days (logarithmic growth phase), 1 mL of algae solution), add SYTOXGREEN dye with an initial concentration of 10 μM, and incubate in the dark for 7 min. The fluorescence intensity of SYTOXGreen nucleic acid dye is measured at 488 nm using an ELISA reader. The cell membrane integrity of Microcystis aeruginosa is as follows: Figure 4As shown, it can be seen from the figure that compared with the control group, the cell membrane integrity is the lowest at 100 mg / L, indicating that the cell membrane damage is more serious than other conditions. Exposure to a relatively high concentration of trichlorfon (100 mg / L) will destroy the cell integrity of cyanobacteria; (2) Risk assessment of algal blooms: Using data processing software such as origin, the logistic model was used to analyze the data on the change of algal density over time at each organophosphorus pesticide concentration, and the maximum population density corresponding to each concentration was obtained. K , the relative position a of the curve to the origin, the value of the intrinsic growth rate r of the population, and then calculate the maximum growth rate R of the population max , the formula is: Where N is the population density at time t, mL -1 ; t is the culture time, d; K is the maximum population density, mL -1 ; a is a constant, indicating the relative position of the curve to the origin; r is the intrinsic growth rate of the population, d -1 ; R is the maximum growth rate of the population, mL -1 ·d -1 ; By comparison K Value and R max The value of the effect of organophosphorus pesticides on the growth of cyanobacteria was evaluated. K Value and R max The larger the value, the higher the risk of algal bloom outbreak; like Figure 5 As shown, in the range of 0.00001mg / L-0.01mg / L, K The value increases with the increase of trichlorfon concentration; under 0.01 mg / L trichlorfon treatment, the maximum K The value is 75.22×10 6 cells / mL, which was 1.12 times that of the control group; K Similar values, R max The value also increases with the increase of trichlorfon concentration. When the concentration is 0.01 mg / L trichlorfon, the Rmax value is 6.90×10 6 cells / mL / d, which was 1.11 times that of the control group; these results indicate that low concentrations of trichlorfon enhance the maximum algal density and growth rate of Microcystis aeruginosa, and this promotion becomes more significant with the increase of trichlorfon concentration, which may lead to an increased risk of cyanobacterial blooms (3) Assessment of the impact of algal toxin synthesis and release: Determination of extracellular algal toxins: Take 1 mL of sample and centrifuge at 10,000 rpm, 4°C for 10 min, and take the supernatant for determination; Determination of total algal toxins: cells need to be broken first to release intracellular algal toxins, 1 mL of sample is quickly frozen with liquid nitrogen for 1 min, thawed naturally, and frozen and thawed three times, then centrifuged to obtain the supernatant for determination ((10000 rpm, 10 min, 4°C)); The concentration of extracellular algal toxins was determined by using a microcystin detection kit. The detection range of the ELISA kit (Beacon, USA) was 0 ppb to 2.0 ppb. Therefore, the sample may need to be diluted before each measurement. When diluting, the solution should be pipetted as accurately as possible, and a larger final solution volume should be selected to reduce the error. Note that the kit should be warmed up in advance before the measurement, and the measurement process should be carried out according to the ELISA kit instructions. Figure 6 As shown, compared with the control (0 mg / L), the concentration of algal toxins per unit cell increased under low concentration of trichlorfon exposure, showing a trend similar to the growth curve, and the concentration increased with the increase of trichlorfon concentration; the maximum concentration of algal toxins per unit cell under 0.01 mg / L trichlorfon exposure was 11.24 μg / L, which was 1.27 times that of the control group; (4) Assessment of ecological risk impact of algae toxins in water bodies: The risk entropy method is used. Specifically, ecological receptors are selected and the peak concentrations of algae toxins in the culture system of organophosphorus pesticides at different concentrations are compared with the toxic endpoint value EC50 measured in the laboratory to characterize the hazard of algae toxins. The risk quotient RQ is obtained. When RQ>1, it is a high risk; when 0.1≤RQ<1, it is a medium risk; when 0.0.1≤RQ<0.1, it is a low risk. In this way, a preliminary judgment on the ecological risk of organophosphorus pesticides is made. The calculation formula is as follows: Wherein, MEC is the mass concentration measured in the environment, ng / L; PNEC is the expected no-effect mass concentration, ng / L; AF is the assessment factor used to select acute toxicity data, which is 1000; The EC50 values ​​of trichlorfon and algae toxin were 16.03 and 70.32 mg / L respectively through the acute toxicity test of luminescent bacteria. The RQ values ​​of water bodies after exposure to different concentrations of trichlorfon were calculated by substituting them into the formula. The results are as follows Figure 7 As shown in the figure, under exposure to 0.01 mg / LTCF, the RQsum value on the 9th day was 13.95, which was significantly greater than 1 and 15.7 times the initial value of 0.89, significantly increasing from low risk to high risk; in addition, the RQ value showed an increasing trend with the increase of trichlorfon concentration, similar to the results of cell growth and algal toxins mentioned above. The results showed that low concentrations of trichlorfon would increase the ecological risk of algal toxins, and with the continuous accumulation of trichlorfon, the ecological risk of algal toxins would further increase.

Claims

1. A multi-index method for evaluating the ecological risk of organophosphorus pesticides based on a microalgae model, characterized in that include: (1) Physiological and biochemical impact assessment: (101) Growth evaluation: At different time points during the cyanobacteria cultivation, the density of cyanobacteria cultured with different concentrations of organophosphorus pesticides was measured, the inhibition rate of organophosphorus pesticides at different concentrations on cyanobacteria was calculated, and the effects of organophosphorus pesticides at different concentrations on the growth of cyanobacteria were evaluated; (102) Photosynthetic activity evaluation: Take the cyanobacteria liquid cultured with different concentrations of organophosphorus pesticides, extract chlorophyll a, measure the chlorophyll a content, and evaluate the effects of different concentrations of organophosphorus pesticides on the photosynthesis of cyanobacteria; (103) Metabolic activity evaluation: Take the cyanobacterial liquid cultured with different concentrations of organophosphorus pesticides, centrifuge to obtain cyanobacterial cells, add ATP extract, freeze the cells in liquid nitrogen, thaw at ambient temperature and repeat the cycle, calculate the ATP content under different concentrations of organophosphorus pesticides, and evaluate the effects of different concentrations of organophosphorus pesticides on the metabolic activity of cyanobacteria; (104) Oxidative stress assessment: Take the cyanobacterial liquid cultured with different concentrations of organophosphorus pesticides, centrifuge to obtain cyanobacterial cells, measure reactive oxygen species, superoxide dismutase, and reduced glutathione, and evaluate the effects of different concentrations of organophosphorus pesticides on oxidative stress of cyanobacteria; (105) Cell membrane integrity: Take cyanobacteria cultured with different concentrations of organophosphorus pesticides, measure the permeability of cyanobacterial cell membranes, and evaluate the effects of different concentrations of organophosphorus pesticides on the integrity of cyanobacterial cell membranes; (2) Algal bloom risk assessment: Use the logistic model to analyze the data on the change of algal density over time at each organophosphorus pesticide concentration and obtain the maximum population density corresponding to each concentration. K , the relative position a of the curve to the origin, the value of the population's intrinsic growth rate r, and then calculate the population's maximum growth rate R max , the formula is: Where N is the population density at time t, mL -1 ; t is the culture time, d; K is the maximum population density, mL -1 ; a is a constant, indicating the relative position of the curve to the origin; r is the intrinsic growth rate of the population, d -1 ; R is the maximum growth rate of the population, mL -1 ·d -1 ; By comparison K Value and R max The value of the effect of organophosphorus pesticides on the growth of cyanobacteria was evaluated. K Value and R max The larger the value, the higher the risk of algal bloom outbreak; (3) Evaluation of the impact of cyanobacterial toxin synthesis and release: Take the cyanobacterial liquid cultured with different concentrations of organophosphorus pesticides, break the algal cells to release the cyanobacterial toxins, and then measure the cyanobacterial toxin concentration to evaluate the impact of different concentrations of organophosphorus pesticides on the cyanobacterial toxin synthesis and release; (4) Ecological risk assessment of algae toxins in water bodies: The risk entropy method is used. Specifically, ecological receptors are selected and the peak concentrations of algae toxins in the culture system of organophosphorus pesticides at different concentrations are compared with the toxic endpoint value EC50 measured in the laboratory to characterize the hazard of algae toxins. The risk quotient RQ is obtained. When RQ>1, it is a high risk; when 0.1≤RQ<1, it is a medium risk; when 0.0.1≤RQ<0.1, it is a low risk. In this way, a preliminary judgment on the ecological risk of organophosphorus pesticides is made. The calculation formula is as follows: Wherein, MEC is the mass concentration measured in the environment, ng / L; PNEC is the expected no-effect mass concentration, ng / L; AF is the assessment factor used to select acute toxicity data, which is 1000.

2. The multi-index method for evaluating the ecological risk of organophosphorus pesticides based on a microalgae model according to claim 1 is characterized in that The cyanobacteria is Microcystis aeruginosa.

3. The multi-index method for evaluating the ecological risk of organophosphorus pesticides based on a microalgae model according to claim 1 is characterized in that The specific method of culturing the different concentrations of organophosphorus pesticides is as follows: the initial algae density is 1.0×10 6 cells / mL-1.5×10 6 cells / mL of cyanobacteria were exposed to a culture medium containing different concentrations of organophosphorus pesticides. The culture medium was 250mL of BG11 medium. The culture conditions were: temperature 25±1℃, light intensity 2000lx, light-dark ratio 12h:12h, humidity 50%, and continuous shaking at 120rpm.

4. The multi-index method for evaluating the ecological risk of organophosphorus pesticides based on a microalgae model according to claim 3 is characterized in that The organophosphorus pesticides of different concentrations are set in multiple groups within the actual water concentration range according to the concentration change trend, including a blank control group and the concentration changes of the target organophosphorus pesticide during accumulation, degradation and transformation in the water body.

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