Method for evaluating PFAS toxicity based on phytoplankton

Abstract

The invention discloses a phytoplankton-based PFAS toxicity evaluation method, which is an efficient detection system using a specific variety of phytoplankton as an indicator organism and is used for evaluating the influence of perfluoroalkyl and polyfluoroalkyl substances on the environment. The system can quickly and accurately determine the toxicity level of PFASs in the water body by monitoring the change of the growth state of phytoplankton. Compared with the traditional chemical analysis method, the invention provides a more accurate PFASs environmental toxicity detection method, which has the advantages of short period, simplicity and convenience in operation and lower cost, and can more truly reflect the ecological effect of PFASs.

Description

Technical Field

[0001] The present invention relates to the field of environmental toxicology, and in particular to an efficient PFASs toxicity assessment method based on phytoplankton. Background Art

[0002] PFASs are a class of persistent organic pollutants widely used in industrial production and daily life. Due to their high stability, they are difficult to degrade and pose a potential threat to the ecological environment. Currently, the commonly used PFASs toxicity assessment methods mainly include chemical analysis methods such as chromatography-mass spectrometry. Although these methods can provide quantitative data, they are time-consuming, costly, and cannot directly reflect ecological impacts. Therefore, developing a biological detection method that can quickly and accurately evaluate the ecotoxicity of PFASs has become a research focus. Summary of the invention

[0003] The present invention aims to overcome the deficiencies of the prior art and provide a method for evaluating the toxicity of PFASs using phytoplankton, so as to overcome the deficiencies of the prior art and achieve rapid and accurate evaluation of the ecotoxicity of PFASs.

[0004] The technical solution of the present invention is a method for evaluating PFAS toxicity based on phytoplankton, comprising the following steps:

[0005] (1) Chlorella sp. was selected as the indicator organism based on the sensitivity of phytoplankton. The complete growth cycle of Chlorella sp. is about 14 days.

[0006] (2) Design PFAS standard solutions with different concentrations of 50-500 mg / L, as well as a control group. All experiments were conducted under the same environment;

[0007] The specific conditions are as follows: the initial density of algae is 1×10 6 cell / μL, light intensity 2000-3000lx, photoperiod set to 12h light / 12h dark, ambient temperature 25℃;

[0008] (3) algal density was measured by flow cytometry on the 1st, 3rd, 5th, and 7th day after the addition of PFASs;

[0009] (4) Calculate IC50 values ​​to quantify the toxicity of PFASs.

[0010] The control group did not add PFASs.

[0011] In step (2), the concentration of the PFAS standard solution is set at 100-150 mg / L.

[0012] In step (2), the concentration of the PFAS standard solution is set at 150-200 mg / L.

[0013] In step (2), the concentration of the PFAS standard solution is set at 200-300 mg / L.

[0014] Furthermore, the Chlorella sp. was used as an indicator organism, and in order to more intuitively observe the toxicity differences of different PFASs, BG11 culture medium was added to make it enter the logarithmic growth phase before the toxicity test experiment;

[0015] The components of BG11 medium are shown in Table 1 below:

[0016] Table 1

[0017]

[0018] Furthermore, the present invention designs standard solutions containing different concentrations of PFASs and sets up a control group, with three biological parallels for each concentration.

[0019] The present invention has the following advantages:

[0020] (1) High efficiency: By observing the changes in the growth status of phytoplankton, conclusions can be drawn in a relatively short period of time.

[0021] (2) Accuracy: Biological indicators are used to directly reflect the ecological effects of PFASs, which is more comprehensive than single chemical analysis.

[0022] (3) Economical: Compared with traditional chemical analysis methods, the present invention requires simple equipment, is easy to operate, and has low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 Effects of different concentrations of PFASs on algae growth: (a) PFOA, (b) HFPO-DA, (c) HFPO-TA;

[0024] Figure 2 PFASs concentration-inhibition rate DoseResp fitting curve. DETAILED DESCRIPTION

[0025] The present invention is further described below in conjunction with the accompanying drawings and specific implementations. It should be emphasized that the following description is only for illustrative purposes and is not intended to limit the scope of use and application of the present invention.

[0026] The present invention selects specific types of phytoplankton as indicator organisms, monitors the changes in their growth state after exposure to PFASs solutions of different concentrations, and then evaluates the toxicity level of PFASs. The specific technical solution is as follows:

[0027] (1) Selection of phytoplankton: Chlorella sp. was selected as the indicator organism based on the characteristics of PFASs and the sensitivity of phytoplankton.

[0028] (2) Experimental conditions: PFAS standard solutions with different concentrations of 50, 100, 150, 200, 300, and 500 mg / L were designed, as well as a control group (without PFASs). All experiments were conducted under the same environment, and the specific conditions are as follows:

[0029] The initial density of algae was 1×10 6 cell / μL, light intensity 1000-2000lx, photoperiod set to 12h light / 12h dark, ambient temperature 25℃.

[0030] (3) Growth status assessment: The algal density was measured by flow cytometry on the 1st, 3rd, 5th, and 7th day after the addition of PFASs.

[0031] (4) Data analysis: The IC50 (half-maximal inhibitory concentration) index was calculated based on the experimental results to quantify the toxicity of PFAS.

[0032] In the embodiment, the IC50 (half maximal inhibitory concentration) index is calculated based on the experimental results, comprising the following steps:

[0033] 1) Calculation of biomass inhibition rate:

[0034]

[0035] Y c represents the algae density of the control group (cell / μL), Y t Represents the density of algae exposed to PFASs solution (cell / μL).

[0036] 2) In order to more accurately evaluate the toxicity of PFASs, the present invention uses the DoseResp model to fit the experimental data to calculate the IC50 value. The DoseResp model is a nonlinear regression model used to describe the relationship between dose and response.

[0037]

[0038] f(x) is the response variable, representing the biomass inhibition rate or other response index;

[0039] xx is the dose variable, i.e., the concentration of PFASs;

[0040] a is the maximum response (the upper limit of the response);

[0041] d is the minimum response (lower limit of the response);

[0042] c is the IC50 value, which is the dose that causes the response variable to reach the middle value (usually a+da+d / 2);

[0043] b is the steepness parameter, which determines the shape of the curve (a larger bb value means a steeper curve).

[0044] The present invention selects and constructs a model according to the above description, and performs toxicity tests using PFOA (CAS NO. 335-67-1), HFPO-DA (CAS NO. 13252-13-6), and HFPO-TA (CAS NO. 13252-14-7) as examples.

[0045] Table 1 DoseResp fitting IC50 values ​​and fitting performance

[0046] Compound Model <![CDATA[R 2 ]]> IC50 PFOA DoseResp 0.97 211 HPFO-DA DoseResp 0.99 188 HPFO-TA DoseResp 0.99 236

[0047] Figure 1 The effects of different concentrations of PFASs on algae growth are shown in Table 2. Figure 1 It can be seen that high concentrations of PFASs have a significant inhibitory effect on the growth of algae.

[0048] Figure 2 The DoseResp model fitting curve of PFASs concentration-inhibition rate can be obtained according to the model. The corresponding concentration of 50% inhibition rate can be obtained. The corresponding half inhibition concentration IC50 of PFOA, HFPO-DA and HFPO-TA are 211, 188 and 236 mg / L respectively. It can be obtained that the toxicity relationship is HFPO-DA>PFOA>HFPO-TA.

Claims

1. A method for evaluating PFAS toxicity based on phytoplankton, characterized in that: The following steps are involved: (1) Chlorella sp. was selected as the indicator organism based on the sensitivity of phytoplankton, among which Chlorella sp. A complete growth cycle is 14±5 days; (2) Design PFAS standard solutions of different concentrations of 50-500 mg / L, as well as a control group. All experiments were conducted under the same environment. The specific conditions are as follows: the initial density of algae was 1×10 6 cell / μL, light intensity 2000-3000lx, photoperiod set to 12h light / 12h dark, ambient temperature 25℃; (3) algal density was measured by flow cytometry on the 1st, 3rd, 5th, and 7th day after the addition of PFASs; (4) Calculate IC50 values ​​to quantify the toxicity of PFASs.

2. The evaluation method according to claim 1, characterized in that: The Chlorella sp. was used as an indicator organism and was added into BG11 culture medium to make it enter the logarithmic growth phase before the toxicity test experiment.

3. The evaluation method according to claim 1, characterized in that: Standard solutions containing different concentrations of PFASs were designed and a control group was set up, with three biological parallels for each concentration.

4. The evaluation method according to claim 1, characterized in that: In step (2), the concentration of the PFAS standard solution is set at 100-150 mg / L.

5. The evaluation method according to claim 1, characterized in that: In step (2), the concentration of the PFAS standard solution is set at 150-200 mg / L.

6. The evaluation method according to claim 1, characterized in that: In step (2), the concentration of the PFAS standard solution is set at 200-300 mg / L.

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