1. A regional protection aquatic organism water quality benchmark derivation method for optimally controlling heavy metal pollutant chromium is characterized by comprising the following specific steps:

(1) collection and screening of toxicity data

The toxicity data collection is from toxicity databases at home and abroad, publicly published file reports and toxicity data obtained by carrying out heavy metal toxicity experiments on the local aquatic organisms, after the data are collected, the obtained data are evaluated and screened, and data of non-regional characteristic species, data without setting a control group and blank group tests and data with overlarge difference of death numbers of the control group are removed;

(2) species screening

Selecting representative aquatic organisms according to the biological characteristics of the region to establish a water quality standard, and performing species inspection and screening on heavy metal toxicity experiments and data collected from a database;

(3) water quality benchmark derivation

Calculating average acute/chronic value

According to the formulas (1) to (2), SMAV and SMCV are calculated in a divided manner,

in the formula: SMAV_iSpecies mean acute value, μ g/L, for species i;

SMCV_ispecies mean chronic value, μ g/L, for species i;

ATV-acute toxicity value, μ g/L;

CTV-chronic toxicity value, μ g/L;

m-ATV of species i_HThe number of the cells is two;

n-CTV of species i_HThe number of the cells is two;

i-a species, dimensionless;

distribution test of toxicity data

For SMAV_iAnd SMCV_iRespectively carrying out normal distribution test, namely K-S test, if the normal distribution is not met, carrying out re-test after logarithmic transformation, and according to the requirement of 'model fitting and evaluation' on data meeting the normal distributionPerforming species sensitivity distribution model fitting, namely SSD model fitting;

calculating cumulative probability

The species SMAV_i/SMCV_iOr the logarithm values are respectively sorted from small to large, the toxicity rank R is determined, the rank of the minimum toxicity value is 1, the rank of the second order is 2, the sequence is arranged in sequence, if the toxicity values of two or more species are the same, the two or more species are randomly arranged into continuous ranks, the number of the species under each rank is 1, the cumulative probability P of the species is respectively calculated, and the P is R/(N +1),

model fitting and evaluation

SMAV_i/SMCV_iTaking the logarithm of base 10, and dividing lg (SMAV)_i)/lg(SMCV_i) As an argument in the model fitting, lg (SMAV)_i)/lg(SMCV_i) Corresponding P is a dependent variable, China-WQC is led in to carry out SSD model fitting, and the determining coefficient r of the model fitting is used²The method comprises the following steps of (1) determining an optimal fitting model according to results of Root Mean Square (RMSE), residual Sum of Squares (SSE) and K-S tests, wherein the independent variables are required to be positive numbers by a lognormal distribution model and a loglogistic distribution model;

(4) determination of a reference

Determining the acute/chronic 5% species hazard concentration HC according to the SSD curve fitted by the best fit model₅And dividing the water quality standard value by the evaluation factor to obtain the water quality standard value of the freshwater aquatic organisms.

2. The method for deducing the water quality benchmark of the regional protection aquatic organism for the optimal control of the heavy metal pollutant chromium according to the claim 1, characterized in that the toxicity data is collected and screened mainly by the following points:

a. the experimental method of the selected data is consistent with the national standard experimental method, and the selected data has clear physicochemical index measurement data and method requirements;

b. only local aquatic organisms in the region are selected, and species-related toxicity data of non-selected regions are removed;

c. in an acute toxicity experiment, when the tested species is daphnia type organisms, the experiment data with the longest period of 48h LC should be selected₅₀/EC₅₀As an experimental indicator of acute toxicity; the fish and other organisms are in 96h LC₅₀Or EC₅₀Shows that if the data of the same fish experiment is 96 hours, 24 hours, 48 hours and 72 hours are abandoned, h is hour, no feeding is carried out during the acute toxicity test period, and LC₅₀At a semi-lethal concentration, EC₅₀Half maximal effect concentration;

d. selecting toxicity data with the lowest affecting concentration LOEC or the largest non-affecting concentration NOEC as the final value of the experiment for more than 14d as an experiment index in a chronic toxicity experiment;

e. in the experiment of aquatic plants, an acute toxicity experiment is used as a standard test of algae, and 96h LC is selected₅₀/EC₅₀Toxicity data of (a); the chronic toxicity test is adopted for the underwater acoustic vascular bundle plants, and long-term LC is selected₅₀/EC₅₀To show the results of toxicity experiments.

3. The derivation method for the water quality standard of the regional protection aquatic organisms with the optimal control of the heavy metal pollutant chromium according to claim 1, wherein the species screening specifically requires the following steps:

1) carpidae in the class teleost;

2) non-cyprinid in the class teleost;

3) another family in the phylum vertebrates, other than 1) or 2);

4) a zooplankton;

5) a benthic animal;

6) an insect;

7) a family other than the phylum arthropoda or phylum chordata;

8) a member of any order of insects or any member not mentioned above;

9) contains at least one of the most sensitive phytoplankton or aquatic plant.

Background

The water quality standard is a scientific basis for determining the water environment management standard and is also a scientific basis for developing water environment quality evaluation and determining a water environment protection target and direction. The water environment reference and the standard jointly form an important guideline for water environment management, so that the aquatic organisms are protected from negative ecological effects caused by pollutants in the water body, and the important role in environmental protection is played. The water quality reference value is regional, the characteristics of biological systems in different regions are different, and the environmental behaviors and the toxicological effects of pollutants can be greatly different, so that the water quality reference value is different.

Although China has successively provided a series of legal rules and documents of relevant water quality standards, most of the derivation of the water quality reference value refers to developed countries such as the United states and Europe, and the toxicity data of local aquatic organisms cannot be systematically and comprehensively utilized to derive the water quality reference value in the selection of the toxicity data. Therefore, when a water quality standard is established, the research on water quality standards cannot be carried out according to the national conditions of China, so that the established water quality standard is difficult to reflect the regional characteristics of China and lacks scientific effectiveness. Moreover, the topography of China is complex, the environmental pollution is diversified, and the water environments of different watersheds have different regional characteristics due to differences of species, climate, geographical positions and the like. Therefore, basin or regional water environment management and pollution control should be established on the basis of national water quality benchmark derivation, so that scientific and effective protection of the water environment can be realized, and a powerful basis is provided for the construction of the ecological risk assessment of the heavy metal in the water body.

Disclosure of Invention

The invention aims to provide a derivation method for the water quality benchmark of regional protection aquatic organisms for optimally controlling heavy metal pollutant chromium, which provides effective protection for watershed or regional aquatic organisms and provides technical support for regional water environment management and water quality benchmark establishment.

In order to achieve the purpose, the invention provides the following technical scheme: a regional protection aquatic organism water quality benchmark derivation method for optimally controlling heavy metal pollutant chromium comprises the following specific steps:

(1) collection and screening of toxicity data

Toxicity data collection is derived from the published reports of toxicity databases at home and abroad and toxicity data obtained by carrying out corresponding heavy metal chromium toxicity experiments on local aquatic organisms. Because the water quality reference derivation needs to meet the biological data of the three-door five-family department, which meets the requirements of the guideline, the toxicity data needs to be supplemented by experiments aiming at the indigenous organisms under the condition that the collected data can not meet the derivation requirements. In the data collection part, after data collection, the obtained data needs to be evaluated and screened, the data of non-selected regional characteristic species are removed, and the data without setting the experiment of a control group and a blank group and the data with excessive difference of the death numbers of the control group are removed;

(2) principle of species selection

The most critical point for establishing regional water quality benchmark is that the aquatic organisms used for benchmark derivation need to be the species in the region. Screening effective data according to the biological system characteristics of the region, selecting representative aquatic organisms to complement the data, and finally using the two groups of data together for deducing the water quality benchmark;

(3) water quality benchmark derivation

Calculating average acute/chronic value

According to the formulas (1) to (2), SMAV and SMCV are calculated in a divided manner,

in the formula: SMAV_iSpecies mean acute value, μ g/L, for species i;

SMCV_ispecies mean chronic value, μ g/L, for species i;

m is the number of ATVs of the species i;

n is the number of CTV of the species i;

i-a species, dimensionless;

distribution test of toxicity data

For SMAV_iAnd SMCV_iRespectively carrying out normal distribution test, namely K-S test, if the normal distribution is not met, carrying out logarithmic transformation and then carrying out re-test, and carrying out species sensitivity distribution model fitting on data which are in accordance with the normal distribution according to the requirement of 'model fitting and evaluation', namely SSD model fitting;

calculating cumulative probability

The species SMAV_i/SMCV_iOr the logarithm values are respectively sorted from small to large, the toxicity rank R is determined, the rank of the minimum toxicity value is 1, the rank of the second order is 2, the sequence is arranged in sequence, if the toxicity values of two or more species are the same, the two or more species are randomly arranged into continuous ranks, the number of the species under each rank is 1, the cumulative probability P of the species is respectively calculated, and the P is R/(N +1),

model fitting and evaluation

SMAV_i/SMCV_iTaking the logarithm of base 10, and dividing lg (SMAV)_i)/lg(SMCV_i) As an argument in the model fitting, lg (SMAV)_i)/lg(SMCV_i) Corresponding P is a dependent variable, China-WQC is introduced to carry out SSD model fitting, and a decision system for model fitting is determinedNumber r²The method comprises the following steps of (1) determining an optimal fitting model according to results of Root Mean Square (RMSE), residual Sum of Squares (SSE) and K-S tests, wherein the independent variables are required to be positive numbers by a lognormal distribution model and a loglogistic distribution model;

(4) determination of a reference

Determining the acute/chronic 5% species hazard concentration HC according to the SSD curve fitted by the best fit model₅And dividing the value by the evaluation factor to obtain the short-term water quality reference value of the freshwater aquatic organisms. And under the condition of insufficient chronic toxicity data, deriving and obtaining a long-term water quality reference value according to the acute-chronic ratio.

The toxicity data is collected and screened mainly by the following points:

a. the experimental method of the selected data is consistent with the national standard experimental method, and the selected data has clear physicochemical index measurement data and method requirements;

b. only local aquatic organisms in the region are selected, and species-related toxicity data of non-selected regions are removed;

c. in an acute toxicity experiment, when the tested species is daphnia type organisms, the experiment data with the longest period of 48h LC should be selected₅₀/EC₅₀As an experimental indicator of acute toxicity; the fish and other organisms are in 96h LC₅₀Or EC₅₀Shows that if the data of the same fish experiment is 96 hours, 24 hours, 48 hours and 72 hours are abandoned, the fish experiment is hours, the fish can not be fed during the acute toxicity test period, and LC₅₀At a semi-lethal concentration, EC₅₀Half maximal effect concentration;

d. selecting toxicity data with the lowest affecting concentration LOEC or the largest non-affecting concentration NOEC as the final value of the experiment for more than 14d as an experiment index in a chronic toxicity experiment;

e. in the experiment of aquatic plants, an acute toxicity experiment is used as a standard test of algae, and 96h LC is selected₅₀/EC₅₀Toxicity data of (a); the chronic toxicity test is adopted for the underwater acoustic vascular bundle plants, and long-term LC is selected₅₀/EC₅₀To show the results of toxicity experiments.

The species screening specifically requires the following:

1) carpidae in the class teleost;

2) non-cyprinid in the class teleost;

3) another family in the phylum vertebrates, other than 1) or 2);

4) a zooplankton;

5) a benthic animal;

6) an insect;

7) a family other than the phylum arthropoda or phylum chordata;

8) a member of any order of insects or any member not mentioned above;

9) contains at least one of the most sensitive phytoplankton or aquatic plant.

Compared with the prior art, the invention has the beneficial effects that: according to the method, through screening of local species, representative aquatic organisms are selected for reference derivation, and the toxicity data of local species and local species are highlighted, so that the reference value can be better suitable for water environment protection of watershed places, and the ecological environment can be more scientifically and effectively protected.

Drawings

FIG. 1 is a curve fitted to a model of the distribution of 5 SSD of chromium to lake Taihu aquatic organisms.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The following examples are set forth to provide those of ordinary skill in the art with a more complete understanding of the present invention, and are not to be construed as limiting the invention in any way.

In this embodiment, a water quality reference derivation method of heavy metal chromium is taken as an example, and the specific steps are as follows:

(1) collection and screening of toxicity data

After the toxicity data is collected, the data needs to be screened and removed, and the screening and removing principle is mainly based on the related documents of the United states EPA and the technical guidance of the quality standard of freshwater aquatic organisms issued by the China (HJ 831-2017). The method mainly comprises the following points:

a. the experimental method of the selected data is consistent with the national standard experimental method, and the selected data has definite physicochemical index measurement data and method requirements, such as exposure type, hydration factor, period length, exposure type and the like;

b. only local aquatic organisms in the region are selected, and non-regional species toxicity data are removed;

c. in the acute toxicity test, when the tested species is daphnia species, the test data (48h LC) with the longest period should be selected₅₀/EC₅₀) As an experimental indicator of acute toxicity; the fish and other organisms are in 96h LC₅₀Or EC₅₀The data of 24h, 48h and 72h are abandoned if the data of 96h exist in the same fish experiment. No feeding is needed during acute toxicity experiments;

d. selecting toxicity data with LOEC or NOEC as final value of the experiment for more than 14d as experiment index in chronic toxicity experiment;

e. in the experiment of aquatic plants, an acute toxicity experiment is used as a standard test of algae, and 96h LC is selected₅₀/EC₅₀Toxicity data of (a); the chronic toxicity test is adopted for the underwater acoustic vascular bundle plants, and long-term LC is selected₅₀/EC₅₀To show the results of toxicity experiments;

(2) species screening

The rejected and screened toxicity data meet the requirements of 'three-door eight-family', and according to the regional characteristics of China, the final toxicity data also meet at least three nutrition levels including primary producers, primary consumers and secondary consumers, so that the toxicity data can be used for deducing the water quality standard, and the specific screening requirements are as follows:

a. carpidae in the class teleost;

b. non-cyprinid in Osteichthyes (such as Hemisalanx laticifera, Pelteobagrus fulvidraco, Misgurni anguillicaudati, etc.);

c. another family (not a or b) in the phylum vertebrales (possibly in the class teleostean or in the class amphibian, etc.);

d. a zooplankton (e.g., cheilogramma, cyclopia, etc.);

e. a benthonic animal (such as Exopalaemon modestus, Cipangopaludina chinensis, Corbicula fluminea, Lumbriatus lumbricus, etc.);

f. an insect (such as Chironomus, Rotifer, Brachionus calycinus, and Chitosan);

g. a family other than the phylum Arthropoda or chordata (e.g., Protozoa, Annelida, Mollusca, etc.);

h. a member of any order of insects or any member not mentioned above;

i. contains at least one of the most sensitive phytoplankton or aquatic plant.

(3) Water quality benchmark derivation

54 reliable toxicity data are obtained through literature search collection and screening. These 54 acute data relate to 14 species in total, of which: 14 species of Taihu native soil, including Acute Toxicity Values (ATV) of the screened species such as crucian, pelteobagrus fulvidraco and chub widely distributed in Taihu lake water, and calculating the average acute toxicity value SMAV of the species according to a fitting formula (1). Arranged as in table 1:

TABLE 1 mean acute value and cumulative probability of chromium vs. Taihu lake aquatic species

(4) Model fitting and evaluation

And the normalized SMAV is brought into SPSS 26 software for normal test, and the K-S test result shows that the acute toxicity value data accords with normal distribution and meets the fitting requirement of an SSD model. And substituting the SMAV value into the software China-WQC to obtain the fitting results of the five models. Selecting a best-fit model, R thereof²Maximum, while the RMSE and SSE values are both smaller than the other four models, the simulation of this modelThe resultant is used as the basis for deducing the short-term water quality standard of the aquatic organisms protected by chromium. The fitting results are shown in table 2 below:

TABLE 2 chromium short-term Water quality reference model fitting results

(5) Fiducial determination

Determining the chromium acute 5% species hazard concentration HC according to the SSD curve fitted by the optimal fitting model₅62.66, and dividing by the evaluation factor 2 to obtain the short-term water quality reference value of 31 mug/L (rounded) for protecting aquatic organisms in the chrome Taihu lake region. According to the USEPA (1995) chromium acute-chronic ratio 2.917, a long-term water quality reference value of 22 mug/L (rounded) for protecting aquatic organisms in the chromium Taihu lake region is obtained.

Those skilled in the art should understand that the water quality monitoring in our country is lack and the local biological toxicity data is less extensive, and the above description is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention; all equivalent changes and modifications made according to the present invention are covered by the claims of the present invention.

Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.