阅读说明：本技术 有机污染物影响下的水生生态系统种群数量的预测方法 (Method for predicting population quantity of aquatic ecosystem under influence of organic pollutants ) 是由 王颖 徐秋童 范文宏 李晓敏 于 2020-10-20 设计创作，主要内容包括：本发明所述有机污染物影响下的水生生态系统种群数量预测方法,通过分析污染物在生物体内传递转化的过程,建立单一物种的生物体内污染物转化模型(单一物种生物积累模型),进而得到水生生态系统的生物体内有机污染物浓度受摄食行为影响下的变化情况模型；通过分析污染物浓度与种群死亡率之间的关系,建立了单一物种有机污染物毒性效应模型；在Lotka-Volterra模型基础上,引入单一物种有机污染物毒性效应模型后,完成了污染物影响下的水生生态系统食物网种群数量动态模型的构建,以对水生生态系统污染物影响下种群数量的变化进行预测,为研究种群生存阈值、如何保持生态平衡和健康的生态系统提供重要手段和科学的理论依据。(According to the method for predicting the population quantity of the aquatic ecosystem under the influence of the organic pollutants, disclosed by the invention, an in-vivo pollutant conversion model (a single-species organism accumulation model) of a single species is established by analyzing the process of transferring and converting the pollutants in an organism, so that a change condition model of the aquatic ecosystem under the influence of ingestion behaviors on the concentration of the organic pollutants in the organism is obtained; establishing a single-species organic pollutant toxicity effect model by analyzing the relationship between the pollutant concentration and the population mortality; on the basis of a Lotka-Volterra model, after a toxic effect model of organic pollutants of a single species is introduced, the construction of a dynamic model of the population quantity of a food net of an aquatic ecosystem under the influence of the pollutants is completed, so that the change of the population quantity under the influence of the pollutants of the aquatic ecosystem is predicted, and an important means and a scientific theoretical basis are provided for researching the population survival threshold value and how to keep ecological balance and a healthy ecosystem.)

1. The method for predicting the population quantity of the aquatic ecosystem under the influence of organic pollutants is characterized by comprising the following steps,

s1, constructing an in-vivo pollutant transformation model through the transfer and transformation process of the organic pollutants in the organism, and further obtaining a change condition model of the concentration of the organic pollutants in the organism of the aquatic ecosystem under the influence of ingestion behaviors;

s2, establishing an equivalent relation for the same organic pollutants accumulated when the organisms die through the in-vivo pollutant conversion model to obtain a model of the change condition of the concentration of the organic pollutants in the water body influenced by the ingestion of the organisms,

s3, comparing the fitting effect of the species sensitivity distribution model of the organism by analyzing the data of the organic pollutant concentration and the biological lethality rate, and constructing a single species organic pollutant toxicity effect model;

s4, constructing a population quantity dynamic model of the aquatic ecosystem food net under the influence of pollutants; the dynamic change model of the number of the food net populations is at least related to the natural growth rate and the natural mortality rate of each nutrition level biological population in the food net of the aquatic ecosystem, the predation and predation relation among each nutrition level biological population and the toxic lethal effect of pollutants on each nutrition level biological population; and the toxic lethal effect of the pollutant on each nutritional level biological population is calculated and obtained through the single-species pollutant toxic effect model and the in-vivo pollutant transformation model.

2. The method for predicting population quantity of an aquatic ecosystem according to claim 2, wherein in the step S1, an in-vivo pollutant transformation model is constructed through a process of transferring and transforming organic pollutants in an organism, and a change situation model of organic pollutant concentration in the organism of the aquatic ecosystem under the influence of feeding behaviors is obtained, specifically comprising the following steps:

s1.1, because the main intake route of the organic pollutants in the organism comprises the intake from food and the direct acquisition from a water body, the in-organism pollutant conversion model is expressed by the following differential equation of the pollutant transfer conversion in the organism:

in the formula, C_B-concentration of organic contaminants in the organism, mg/g;

C_w-concentration of organic pollutants in water, mg/L;

C_f-concentration of organic contaminants in food, mg/g;

k_wthe absorption rate constant of the organic pollutants in the water body is unitless;

k_f-the rate constant of absorption of organic contaminants in food, unitless;

k₂-organic contaminant discharge rate constant, unitless;

s1.2, because the long-term toxic effect of the organic pollutants needs to be simulated, the organic pollutants in organisms and water body environment are considered to reach an equilibrium state, namely dC_B0/dt; so that the concentration of organic contaminants C in the living body_BCan be represented by the following formula:

3. the method for predicting population quantity of an aquatic ecosystem of claim 2, wherein in step S2, an equivalent relation is established for the same organic pollutants accumulated when the organisms die through the in-vivo organic pollutant transformation model, and a model of the variation of the concentration of the organic pollutants in the water body due to the absorption of the organisms is obtained,

the method specifically comprises the following steps:

C_B＝C′_B (2.1)

that is to say that the first and second electrodes,

k_wC_w＝k_wC′_ω+k_fC_f (2.3)

therefore, the expression of the model of the change condition of the concentration of the organic pollutants in the water body influenced by the ingestion of the organisms is as follows:

in the formula, C_wThe concentration of organic pollutants in the water body, mg/L, when the organisms take the organic pollutants through food is not considered;

C_w' -consider the concentration of organic contaminants in a body of water, mg/L, when the organisms ingest the organic contaminants through food.

4. An aquatic ecosystem population quantity prediction method according to claim 2 or 3, wherein the organic pollutant absorption rate constant k in the water body_wThe method is simplified as follows:

in the formula, E_wThe organic pollutant intake efficiency of the organisms through the water body environment exposure way is unitless;

G_v-the respiration rate of the organism, L/d;

W_B-wet weight of organism, g;

wherein E is_wlogK characteristic of organic pollutants_owIn relation to different logK_owThe value range corresponds to different relational expressions and is the water distribution coefficient of the n-octanol of the organic pollutant; g_vIs the rate of biological uptake of water, which is related to the rate of biological consumption of oxygen and is expressed as:

in the formula, V_oxThe rate of biological consumption of oxygen, mg O₂/d；

C_ox-oxygen concentration in water, mg O₂/L；

C_oxRelated to the temperature and oxygen saturation of the water body, is expressed as:

C_ox＝(-0.24T+14.04)S (1.5)

wherein, T is water temperature, DEG C;

s-dissolved oxygen content in water,%;

and the rate V of biological consumption of oxygen_oxIn relation to the quality of the organism:

combining the formulas 1.4-1.6, the following Gv expression is obtained for fish, invertebrates and zooplankton simultaneously:

the rate constant k of absorption of organic contaminants in said food_fThe method is simplified as follows:

k_f＝E_fR(1.8)

in the formula, E_fThe efficiency of food exposure pathway intake of organic contaminants, unitless; with different E for different species types_fA value;

r-food intake, g prey/(g d);

the organic contaminant discharge rate constant k₂The expression is as follows:

wherein, p is species constant, 445 is taken from fish, 890 is taken from invertebrate, and no unit is taken from invertebrate;

l is the lipid content in the organism, g lipid/g organ.

5. An aquatic ecosystem population quantity prediction method according to claim 4, wherein the absorption rate constant k of organic pollutants in the water body is determined_wExpression and the rate constant k of absorption of organic contaminants in said food_fSubstituting the expression into the model of the change condition of the concentration of the organic pollutants in the water body, which is influenced by the ingestion of the organisms, and obtaining the expression of the model of the change condition of the concentration of the organic pollutants in the water body, which is influenced by the ingestion of the organisms, as follows:

6. the aquatic ecosystem population quantity prediction method of claim 5, wherein the organic pollutants comprise polychlorinated biphenyls (PCBs), species sensitivity distribution models of organisms are compared against the polychlorinated biphenyls (PCBs), a Weber distribution model with a better fitting effect is selected, and according to a cumulative probability function expression of the Weber distribution, an expression of a toxicity effect model of the organic pollutants of a single species is obtained as follows:

in the formula, m and n are parameters for determining the Weber distribution range and the shape respectively;

C_w-considering the content of contaminants in the water body, mg/L, when the organisms ingest organic contaminants through food;

P_i-lethality of organic contaminants to i population.

7. The aquatic ecosystem population quantity prediction method of claim 1, wherein in step S4, constructing a population quantity dynamic model of the aquatic ecosystem food net under the influence of pollutants comprises the following steps:

s4.1 determining the number of trophic levels of organisms in the food net of the aquatic ecosystem and simplifying each trophic level into a representative species,

s4.2, determining the predation relation among the representative species, simplifying the predation relation into a linear predation relation,

s4.3, determining the natural growth rate of the first representative species simplified from the first nutrition level, the natural mortality rate of the representative species simplified from the rest nutrition levels except the first nutrition level, the environment accommodating capacity of the representative species of each nutrition level, the predation rate and the feeding rate among the nutrition levels and the mortality rate of organic pollutants to each representative species, and establishing a dynamic model of the population quantity of the food net of the aquatic ecosystem under the influence of the pollutants based on a Lotka-Volterra model.

8. An aquatic ecosystem population quantity prediction method according to claim 6, wherein the nutrition levels of organisms in the aquatic ecosystem food net include a first nutrition level, a second nutrition level and a third nutrition level, and the step S4 of constructing a population quantity dynamic model of the aquatic ecosystem food net under the influence of pollutants includes the steps of:

s4.1, simplifying the first nutrition level into an X population, simplifying the second nutrition level into a Y population, and simplifying the third nutrition level into a Z population, wherein the population numbers are recorded as X, Y and Z respectively;

s4.2, the X population is a producer, the Y population and the Z population are consumers, and the X population, the Y population and the Z population are in a linear predation relation;

s4.3, establishing a dynamic model of the population quantity of the food net of the aquatic ecosystem under the influence of organic pollutants based on a Lotka-Volterra model, wherein the expression is as follows:

in the formula, K₁-environmental containment of the first trophic class species in units of only;

K₂-environmental containment of the second nutritional grade species in units of only;

K₃-environmental containment of the third trophic class species in units of only;

r-X population natural growth rate, no unit;

d₁，d₂-natural mortality of the Y, Z population, no unit;

a₁-predation rate of Y to X, unitless;

a₂the rate of supply of X to Y is unitless;

b₁-predation rate of Z to Y, unitless;

b₂the rate of Y feeding Z is unitless;

P₁the lethality of organic pollutants to the X population, unitless;

P₂lethality of organic pollutants to Y populations, unitless;

P₃the lethality of organic pollutants to the Z population, unitless;

the formula (2.5) is substituted into the formula (3.1) and then the formula (4.1) - (4.3) are used, and the change situation of the population quantity of the food net of the aquatic ecosystem under the influence of the organic pollutants can be calculated.

9. The method for predicting the population quantity of the aquatic ecosystem according to claim 8, further comprising a step S5 of inputting the formulas (1.1) - (1.9), (2.1) - (2.5), (3.1) and (4.1) - (4.3) into numerical simulation software, and substituting the formula (2.5) into the formula (3.1) and then into the formulas (4.1) - (4.3) in the numerical simulation software, so as to obtain a dynamic model simulation model of the population quantity of the food net of the aquatic ecosystem under the influence of the organic pollutants.

Technical Field

The invention relates to the technical field of biological population quantity change conditions of different biodiversity levels under the influence of organic pollutants, in particular to a method for predicting the population quantity of an aquatic ecosystem under the influence of the organic pollutants.

Background

The same mathematical model describing interspecies relationships was proposed by Lotka and Volterra in 1925 and 1928, respectively, and is called the Lotka-Volterra model. The dynamic change process of the two groups of numbers is described by mainly combining the intra-species competition relationship and the inter-species competition relationship (formula 1-2).

In the formula, alpha₁₂,α₂₁Is the competition coefficient; k₁And K₂Environmental bearing capacity for species 1 and 2, respectively; n is a radical of₁And N₂Population numbers for species 1 and species 2, respectively; r is₁And r₂The respective maximum intrinsic growth rates of the two species. The model mainly represents the retarding effect of the individual on population growth through the occupied resource space. 1/K₁Can be understood as the resource space occupied by the individual of species 1, N₁/K₁That is, the resource space already occupied by species 1, the effect of the resource space already occupied by species 2 on species 1 needs to be at N₂/K₁On the basis of the corresponding competition coefficient alpha₁₂. The expression pattern of species 2 population numbers is the same. The Lotka-Volterra model shows the relationship of the interaction among the populations from a relatively macroscopic angle, and still is the object of extensive research and the basis of practical application.

With the acceleration of the industrialization process and the increasing severity of the environmental pollution problem, the influence of pollutants on the individual and population of the living beings in the nature is larger and larger, and even the daily survival of the species is threatened. In order to study the mechanism of action and the dynamic impact of pollutants on populations, ecotoxicological dynamics studies based on population ecological model studies were opened by professor t.g. halam and his students in the 80 s of the 20 th century. However, more researches on the population quantity prediction method under the influence of pollutants still focus on theoretical characteristics such as a specific prediction model balance point, various population coexistence threshold conditions, a survival extinction boundary curve and the like, and a prediction method which can be directly applied to an actual natural ecosystem is lacked.

Disclosure of Invention

The method comprises the steps of establishing an in-vivo pollutant conversion model (namely a biological accumulation model) of a single species by analyzing the process of transferring and converting pollutants in an organism; establishing a single species toxicity effect model by analyzing the relationship between the pollutant concentration and the population mortality; on the basis of a Lotka-Volterra model, a toxicity effect model is introduced, so that the construction of a population quantity dynamic model of the food net of the aquatic ecosystem under the influence of pollutants is completed, the change of the population quantity under the influence of the pollutants of the aquatic ecosystem is predicted, and an important means and a scientific basis are provided for keeping ecological balance and how to keep a healthy ecosystem.

The technical scheme of the invention is as follows:

the method for predicting the population quantity of the aquatic ecosystem under the influence of organic pollutants comprises the following steps,

s1, constructing an in-vivo pollutant transformation model through the transfer and transformation process of the organic pollutants in the organism, and further obtaining a change condition model of the concentration of the organic pollutants in the organism of the aquatic ecosystem under the influence of ingestion behaviors;

s2, establishing an equivalent relation for the same organic pollutants accumulated when the organisms die through the in-vivo pollutant conversion model to obtain a model of the change condition of the concentration of the organic pollutants in the water body influenced by the ingestion of the organisms,

s3, comparing the fitting effect of the species sensitivity distribution model of the organism by analyzing the data of the organic pollutant concentration and the biological lethality rate, and constructing a single species organic pollutant toxicity effect model;

s4, constructing a population quantity dynamic model of the aquatic ecosystem food net under the influence of pollutants; the dynamic change model of the number of the food net populations is at least related to the natural growth rate and the natural mortality rate of each nutrition level biological population in the food net of the aquatic ecosystem, the predation and predation relation among each nutrition level biological population and the toxic lethal effect of pollutants on each nutrition level biological population; and the toxic lethal effect of the pollutant on each nutritional level biological population is calculated and obtained through the single-species pollutant toxic effect model and the in-vivo pollutant transformation model.

Preferably, in step S1, an in vivo pollutant transformation model is constructed through a process of transferring and transforming organic pollutants in a living body, and a change condition model of organic pollutant concentration in a living body of an aquatic ecosystem under the influence of feeding behavior is obtained, which specifically includes the following steps:

s1.1, because the main intake route of the organic pollutants in the organism comprises the intake from food and the direct acquisition from a water body, the in-organism pollutant conversion model is expressed by the following differential equation of the pollutant transfer conversion in the organism:

in the formula, C_B-concentration of organic contaminants in the organism, mg/g;

C_w-concentration of organic pollutants in water, mg/L;

C_f-concentration of organic contaminants in food, mg/g;

k_wthe absorption rate constant of the organic pollutants in the water body is unitless;

k_f-the rate constant of absorption of organic contaminants in food, unitless;

k₂-organic contaminant discharge rate constant, unitless;

s1.2, because the long-term toxic effect of the organic pollutants needs to be simulated, the organic pollutants in organisms and water body environment are considered to reach an equilibrium state, namely dC_B0/dt; so that the concentration of organic contaminants C in the living body_BCan be represented by the following formula:

preferably, in step S2, the equivalent relation is established for the same organic pollutants accumulated when the organisms die by the in-vivo organic pollutant conversion model, a model of the change of the concentration of the organic pollutants in the water body due to the influence of organism ingestion is obtained,

the method specifically comprises the following steps:

C_B＝C′_B (2.1)

that is to say that the first and second electrodes,

k_wC_w＝k_wC′_w+k_fC_f (2.3)

therefore, the expression of the model of the change condition of the concentration of the organic pollutants in the water body influenced by the ingestion of the organisms is as follows:

in the formula, C_wThe concentration of organic pollutants in the water body, mg/L, when the organisms take the organic pollutants through food is not considered;

C_w' -considering the concentration of organic contaminants in the water body when the organisms ingest the organic contaminants through food, mg/L;

preferably, the absorption rate constant k of the organic pollutants in the water body_wThe method is simplified as follows:

in the formula, E_wThe organic pollutant intake efficiency of the organisms through the water body environment exposure way is unitless;

G_v-the respiration rate of the organism, L/d;

W_B-wet weight of organism, g;

wherein E is_wlogK characteristic of organic pollutants_owIn relation to different logK_owThe value range corresponds to different relational expressions and is the water distribution coefficient of the n-octanol of the organic pollutant; g_vIs the rate of biological uptake of water, which is related to the rate of biological consumption of oxygen and is expressed as:

in the formula, V_oxThe rate of biological consumption of oxygen, mg O₂/d；

C_ox-oxygen concentration in water, mg O₂/L；

C_oxRelated to the temperature and oxygen saturation of the water body, is expressed as:

G_ox＝(-0.24T+14.04)S (1.5)

wherein, T is water temperature, DEG C;

s-dissolved oxygen content in water,%;

and the rate V of biological consumption of oxygen_oxIn relation to the quality of the organism:

combining equations 1.4-1.6, the following G is obtained which is suitable for fish, invertebrates and zooplankton simultaneously_vExpression:

the rate constant k of absorption of organic contaminants in said food_fThe method is simplified as follows:

k_f＝E_fR (1.8)

in the formula, E_fThe efficiency of food exposure pathway intake of organic contaminants, unitless; with different E for different species types_fA value;

r-food intake, g prey/(g d);

the organic contaminant discharge rate constant k₂The expression is as follows:

wherein, p is species constant, 445 is taken from fish, 890 is taken from invertebrate, and no unit is taken from invertebrate;

l is the lipid content in the organism, g lipid/g organ;

preferably, the absorption rate constant k of the organic pollutants in the water body is determined_wExpression and the rate constant k of absorption of organic contaminants in said food_fSubstituting the expression into the model of the change condition of the concentration of the organic pollutants in the water body, which is influenced by the ingestion of the organisms, and obtaining the expression of the model of the change condition of the concentration of the organic pollutants in the water body, which is influenced by the ingestion of the organisms, as follows:

6. the aquatic ecosystem population quantity prediction method of claim 5, wherein the organic pollutants comprise polychlorinated biphenyls (PCBs), species sensitivity distribution models of organisms are compared against the polychlorinated biphenyls (PCBs), a Weber distribution model with a better fitting effect is selected, and according to a cumulative probability function expression of the Weber distribution, an expression of a toxicity effect model of the organic pollutants of a single species is obtained as follows:

in the formula, m and n are parameters for determining the Weber distribution range and the shape respectively;

C_w-considering the content of contaminants in the water, mg/L, before the organisms ingest the organic contaminants through food;

P_i-lethality of organic contaminants to i population.

Preferably, in step S4, the constructing a population quantity dynamic model of the food net of the aquatic ecosystem under the influence of the pollutants includes the following steps:

s4.1 determining the number of trophic levels of organisms in the food net of the aquatic ecosystem and simplifying each trophic level into a representative species,

s4.2, determining the predation relation among the representative species, simplifying the predation relation into a linear predation relation,

s4.3, determining the natural growth rate of the first representative species simplified from the first nutrition level, the natural mortality rate of the representative species simplified from the rest nutrition levels except the first nutrition level, the environment accommodating capacity of the representative species of each nutrition level, the predation rate and the feeding rate among the nutrition levels and the mortality rate of organic pollutants to each representative species, and establishing a dynamic model of the population quantity of the food net of the aquatic ecosystem under the influence of the pollutants based on a Lotka-Volterra model.

Preferably, the nutrition levels of the organisms in the aquatic ecosystem food net comprise a first nutrition level, a second nutrition level and a third nutrition level, and the step S4 of constructing a population quantity dynamic model of the aquatic ecosystem food net under the influence of pollutants comprises the following steps:

s4.1, simplifying the first nutrition level into an X population, simplifying the second nutrition level into a Y population, and simplifying the third nutrition level into a Z population, wherein the population numbers are recorded as X, Y and Z respectively;

s4.2, the X population is a producer, the Y population and the Z population are consumers, and the X population, the Y population and the Z population are in a linear predation relation;

s4.3, establishing a dynamic model of the population quantity of the food net of the aquatic ecosystem under the influence of organic pollutants based on a Lotka-Volterra model, wherein the expression is as follows:

in the formula, K₁-environmental containment of the first trophic class species in units of only;

K₂-environmental containment of the second nutritional grade species in units of only;

K₃-environmental containment of the third trophic class species in units of only;

r-X population natural growth rate, no unit;

d₁-natural mortality of the Y population, unitless;

d₂z population natural mortality, unitless;

a₁-predation rate of Y to X, unitless;

a₂the rate of supply of X to Y is unitless;

b₁-predation rate of Z to Y, unitless;

b₂the rate of Y feeding Z is unitless;

P₁the lethality of organic pollutants to the X population, unitless;

P₂lethality of organic pollutants to Y populations, unitless;

P₃the effect of organic contaminants on the Z populationMortality rate, no unit;

the formula (2.5) is substituted into the formula (3.1) and then the formula (4.1) - (4.3) are used, and the change situation of the population quantity of the food net of the aquatic ecosystem under the influence of the organic pollutants can be calculated.

Preferably, the method for predicting the population quantity of the aquatic ecosystem further comprises a step S5 of inputting the formulas (1.1) - (1.9), (2.1) - (2.5), (3.1) and (4.1) - (4.3) into numerical simulation software, and substituting the formula (2.5) into the formula (3.1) and then into the formulas (4.1) - (4.3) in the numerical simulation software, so as to obtain a dynamic model simulation model of the population quantity of the food net of the aquatic ecosystem under the influence of organic pollutants.

Compared with the prior art, the invention has the advantages that: according to the method for predicting the population quantity of the aquatic ecosystem under the influence of the organic pollutants, disclosed by the invention, an in-vivo pollutant conversion model (a single-species organism accumulation model) of a single species is established by analyzing the process of transferring and converting the pollutants in an organism, so that a change condition model of the aquatic ecosystem under the influence of ingestion behaviors on the concentration of the organic pollutants in the organism is obtained; establishing a single-species organic pollutant toxicity effect model by analyzing the relationship between the pollutant concentration and the population mortality; on the basis of a Lotka-Volterra model, after a toxic effect model of organic pollutants of a single species is introduced, the construction of a dynamic model of the population quantity of a food net of an aquatic ecosystem under the influence of the pollutants is completed, so that the change of the population quantity under the influence of the pollutants of the aquatic ecosystem is predicted, and an important means and a scientific theoretical basis are provided for researching the population survival threshold value and how to keep ecological balance and a healthy ecosystem.

Drawings

FIG. 1 is a schematic diagram illustrating the conversion of organic pollutants in organisms in the method for predicting population quantity of aquatic ecosystems under the influence of organic pollutants according to the present invention;

FIG. 2 is a graph showing the predation relationship of a three-nutrition-level ecosystem in the method for predicting population numbers of aquatic ecosystems affected by organic pollutants according to the present invention, wherein FIG. 2(a) is a linear predation relationship and FIG. 2(b) is a triangular predation relationship;

FIG. 3 is a flow chart of the method for predicting population quantity of aquatic ecosystem under the influence of organic pollutants according to the present invention;

FIG. 4(a) is a X, Y, Z population quantity variation curve under the influence of the concentration of a specific pollutant simulated by a population quantity dynamic model simulation model under the influence of an organic pollutant in the method for predicting population quantity of an aquatic ecosystem under the influence of an organic pollutant according to the present invention, wherein a line in an area A is an X population quantity variation curve, a line in an area B is a Y, Z population quantity variation curve, a dotted line is a population quantity variation curve when the concentration of the organic pollutant is 0mg/L, and a solid line is a population quantity variation curve when the concentration of the organic pollutant is 0.1 mg/L;

FIG. 4(B) is a partial enlarged view of a X, Y, Z population quantity variation curve under the influence of the concentration of a specific pollutant simulated by a population quantity dynamic model simulation model under the influence of an organic pollutant in the method for predicting the population quantity of an aquatic ecosystem under the influence of the organic pollutant of the present invention, wherein a line in a B1 region is a Y population quantity variation curve, a line in a B2 region is a Z population quantity variation curve, a dotted line is a population quantity variation curve when the concentration of the organic pollutant is 0mg/L, and a solid line is a population quantity variation curve when the concentration of the organic pollutant is 0.1 mg/L;

FIG. 5 is a X, Y, Z population quantity variation curve under the influence of different pollutant concentrations simulated by a population quantity dynamic model simulation model under the influence of organic pollutants in the method for predicting population quantity of an aquatic ecosystem under the influence of organic pollutants of the present invention, wherein a line in an A region is an X population quantity variation curve, a line in a B region is a Y, Z population quantity variation curve, a dotted line is a population quantity variation curve when the concentration of organic pollutants is 0mg/L, and a solid line is a population quantity variation curve when the concentration of organic pollutants is in a range from 0.01mg/L to 0.05 mg/L;

FIG. 6 is a partial enlarged view of X, Y, Z population quantity variation curves under the influence of different pollutant concentrations simulated by a population quantity dynamic model simulation model under the influence of organic pollutants in the method for predicting population quantity of an aquatic ecosystem under the influence of organic pollutants of the present invention, wherein a line in a B1 region is a Y population quantity variation curve, a line in a B2 region is a Z population quantity variation curve, a dotted line is a population quantity variation curve when the concentration of organic pollutants is 0mg/L, and a solid line is a population quantity variation curve when the concentration of organic pollutants is in a range from 0.01mg/L to 0.05 mg/L;

FIG. 7 is a further partial enlarged view of X, Y, Z population quantity variation curves under the influence of different pollutant concentrations simulated by the population quantity dynamic model simulation model under the influence of organic pollutants in the method for predicting population quantity of an aquatic ecosystem under the influence of organic pollutants of the present invention, wherein the line in the B2 region is a Z population quantity variation curve, the dotted line is the population quantity variation curve when the concentration of organic pollutants is 0mg/L, and the solid line is the population quantity variation curve when the concentration of organic pollutants is in the range of 0.01mg/L to 0.05 mg/L.

Detailed Description

In order to facilitate understanding of the present invention, the present invention will be described in more detail below with reference to specific examples and comparative examples.

Example 1

The method for predicting the population quantity of the aquatic ecosystem under the influence of the organic pollutants, which has a flow chart shown in figure 3 and takes three levels of nutrition as an example, predicts the population quantity of the aquatic ecosystem under the influence of the organic pollutants of X, Y and Z populations and comprises the following steps,

s1, constructing a change condition model of the concentration of organic pollutants in organisms of the aquatic ecosystem under the influence of feeding behaviors;

through the process of transferring and converting organic pollutants in organisms, as shown in fig. 1, the main uptake routes of pollutants in aquatic organisms include the route 1 for taking pollutants from water and the route 2 for taking pollutants from food, and the discharge route is mainly the route 3 for discharging pollutants into water, so that the exchange of organic compounds between organisms and the surrounding environment can use the following differential equation of transferring and converting pollutants in organisms, namely the conversion model of pollutants in organisms is as follows:

in the formula, C_B-concentration of organic contaminants in the organism, mg/g;

C_w-concentration of organic pollutants in water, mg/L;

C_f-concentration of organic contaminants in food, mg/g;

k_wthe absorption rate constant of the organic pollutants in the water body is unitless;

k_f-the rate constant of absorption of organic contaminants in food, unitless;

k₂-organic contaminant discharge rate constant, unitless;

because of the need to simulate the long-term toxic effects of organic pollutants, it is believed that the organic pollutant transport in living organisms and in aqueous environments reaches an equilibrium state, i.e., dC_E0/dt; so that the concentration of organic contaminants C in the living body_BCan be represented by the following formula:

wherein the absorption rate constant k of the organic pollutants in the water body_wThe method is simplified as follows:

in the formula, E_wThe organic pollutant intake efficiency of the organisms through the water body environment exposure way is unitless;

G_V-the respiration rate of the organism, L/d;

W_B-wet weight of organism, g;

wherein E is_wlogK characteristic of organic pollutants_owIn relation to different logK_owThe value ranges correspond to different relations, see (table 1.1):

TABLE 1E_wAnd logK_owIs a relational expression of

In the formula, K_owThe pollutant n-octanol water distribution coefficient is unitless;

wherein G is_VIs the rate of biological uptake of water, which is related to the rate of biological consumption of oxygen and is expressed as:

in the formula, V_oxThe rate of biological consumption of oxygen, mg O₂/d；

C_ox-oxygen concentration in water, mg O₂/L；

C_oxRelated to the temperature and oxygen saturation of the water body, is expressed as:

C_ox＝(-0.24T+14.04)S (1.5)

wherein, T is water temperature, DEG C;

s-dissolved oxygen content in water,%;

and the rate V of biological consumption of oxygen_oxIn relation to the quality of the organism:

combining equations 1.4-1.6, the following G is obtained which is suitable for fish, invertebrates and zooplankton simultaneously_VExpression:

the rate constant k of absorption of organic contaminants in said food_fThe method is simplified as follows:

k_f＝E_fR (1.8)

in the formula, E_fThe efficiency of food exposure pathway intake of organic contaminants, unitless; with different E for different species types_fA value; r-food intake, g prey/(g d); wherein there is a difference in E for different species types_fThe values are shown in Table 2:

TABLE 2E of different species_fValue of

The organic contaminant discharge rate constant k₂The expression is as follows:

wherein, p is species constant, 445 is taken from fish, 890 is taken from invertebrate, and no unit is taken from invertebrate;

l is the lipid content in the organism, g lipid/g organ;

s2, establishing an equivalent relation for the same organic pollutants accumulated when the organisms die through the in-vivo pollutant conversion model, and obtaining a model of the influence change condition of the concentration of the organic pollutants in the water body, which is caused by the ingestion of the organisms, as follows:

C_B＝C′_B (2.1)

that is to say that the first and second electrodes,

k_wC_w＝k_wC′_w+k_fC_f (2.3)

therefore, the expression of the model of the change condition of the concentration of the organic pollutants in the water body influenced by the ingestion of the organisms is as follows:

in the formula, C_wThe concentration of organic pollutants in the water body, mg/L, when the organisms take the organic pollutants through food is not considered;

C_w' -considering the concentration of organic contaminants in the water body when the organisms ingest the organic contaminants through food, mg/L;

absorbing the organic pollutant in the water body with a rate constant k_wExpression and the rate constant k of absorption of organic contaminants in said food_fSubstituting the expression into the model of the change condition of the concentration of the organic pollutants in the water body, which is influenced by the ingestion of the organisms, and obtaining the expression of the model of the change condition of the concentration of the organic pollutants in the water body, which is influenced by the ingestion of the organisms, as follows:

s3, comparing the fitting effect of the species sensitivity distribution model of the organism by analyzing the data of the organic pollutant concentration and the biological lethality rate, and constructing a single species organic pollutant toxicity effect model;

there have been many studies on the relationship between contaminant concentration and the lethality of contaminants to X, Y, Z populations. However, here we are concerned with organic contaminants and set PCBs as the main subject of study, so three general species sensitivity distribution models were compared and finally a weber distribution with better fitting effect was determined.

TABLE 3 comparison of fitting results of three general species sensitivity distribution models

According to the cumulative probability function expression of the Weber distribution, the expression of the toxicity effect model of the organic pollutants of the single species is obtained as follows:

in the formula, m and n are parameters for determining the Weber distribution range and the shape respectively;

C_w-considering the content of contaminants in the water body, mg/L, when the organisms ingest organic contaminants through food;

pi-the lethality of organic contaminants to the i population.

S4, constructing a population quantity dynamic model of the aquatic ecosystem food net under the influence of pollutants;

s4.1, respectively recording the population numbers of the X population, the Y population and the Z population as X, Y and Z; the food net population quantity variation model is a refinement of the Lotka-Volterra model under the influence of contaminants. The food net is a three-trophic-level ecosystem, each trophic level reduced to a species representative. Two predation relationships possible for a three-trophic-level ecosystem are shown in fig. 2, where fig. 2(a) is a linear predation relationship and fig. 2(b) is a triangular predation relationship.

S4.2, the X population is a producer, the Y population and the Z population are consumers, and the X population, the Y population and the Z population are in a linear predation relation, which is shown in a figure 2 (a);

s4.3, establishing a dynamic model of the population quantity of the food net of the aquatic ecosystem under the influence of organic pollutants based on a Lotka-Volterra model, wherein the expression is as follows:

in the formula, K₁-environmental containment of the first trophic class species in units of only;

K₂-environmental containment of the second nutritional grade species in units of only;

K₃-environmental containment of the third trophic class species in units of only;

r-X population natural growth rate, no unit;

d₁-natural mortality of the Y population, unitless;

d₂z population natural mortality, unitless;

a₁-predation rate of Y to X, unitless;

a₂the rate of supply of X to Y is unitless;

b₁-predation rate of Z to Y, unitless;

b₂the rate of Y feeding Z is unitless;

P₁the lethality of organic pollutants to the X population, unitless;

P₂lethality of organic pollutants to Y populations, unitless;

P₃the lethality of organic pollutants to the Z population, unitless;

and substituting the formula (2.5) into the formula (3.1) and then into the formulae (4.1) - (4.3), so that the change conditions of the number of the X population, the Y population and the Z population in the food net of the aquatic ecosystem under the influence of the organic pollutants can be calculated.

In summary, the parameters required for using the model are summarized as follows:

table 4 table of parameters of dynamic model of population number under the influence of organic pollutants

Aiming at an aquatic ecosystem formed by any three nutrition levels, as long as the environmental parameters and species parameters shown in the table above are obtained, the dynamic model of the population quantity under the influence of the constructed pollutants can be substituted to predict the change condition of the population quantity.

Example 2

In addition to the steps described in the above embodiments, the method for predicting population number of aquatic ecosystem under the influence of organic pollutants further comprises the following steps:

s5, inputting the formulas (1.1) - (1.9), (2.1) - (2.5), (3.1) and (4.1) - (4.3) into numerical simulation software, and substituting the formula (2.5) into the formula (3.1) and then into the formulas (4.1) - (4.3) in the numerical simulation software, so as to obtain a dynamic model simulation model of the population quantity of the food net of the aquatic ecosystem under the influence of the organic pollutants.

In numerical simulation software, a reliable dynamic model simulation result of the population quantity of the food net of the aquatic ecosystem under the influence of the organic pollutants is obtained through a dynamic model simulation model of the population quantity of the food net of the aquatic ecosystem under the influence of the organic pollutants, and the following points are also required to be noticed:

s5.1, determining the organic pollutant types and the species contained in the food net

Multiple transfers of contaminants from the aquatic ecosystem occur, from the aquatic environment to the organisms, from within one organism to within another, and from within each organism to the aquatic environment. During each transfer of the compound, the final state is equilibrium. At present, the prediction technology mainly aims at lipophilic organic compounds, and because the lipophilic organic compounds are mainly present in tissues with higher content of biological lipid, the transfer process of the compounds is actually a process of continuously distributing and diffusing in two phases, and can directly pass through the logarithm of the n-octanol-water partition coefficient, namely logK_owAnd (4) performing representation. Therefore, we first need to identify the class of lipophilic organic compounds under investigation, here we use polychlorinated biphenyls (PCBs) as an example.

In addition, many parameters of the model used to predict population size changes (e.g., organism wet weight, Lotka-Volterra model parameters, etc.) are also related to a particular species. In practice, these values vary with the food network formed by the different species. This example illustrates a food chain comprising midge, bluegill sunfish and largemouth bass.

S5.2, determining parameter values required by a dynamic model simulation model of the population quantity of the food nets of the aquatic ecosystem under the influence of the organic pollutants;

the required parameters are classified according to their characteristics. The first is a parameter related only to water and organic pollutants: c_WKow, T and S; the second category is the parameters associated with the biotoxicity of organic pollutants: p, E_f，L，W_BR, m and n; the third category is the Lotka-Volterra model-related parameters: r, d₁，d₂，a₁，a₂，b₁，b₂，K₁，K₂And K₃。

(1) Parameters related to water body and pollutants

Wherein, C_wAnd K_OWCan be directly obtained from the literature according to the type of the pollutant, wherein C_wSlightly above the concentration given in the water quality standard. The values of T and S are mainly referred to the standards given in the review literature for the evaluation method of BCF and BAF of organic matters: the recommended temperature for most species BCF assays is 20-25 ℃; meanwhile, the oxygen dissolved in water must be more than 60% by the measurement of BCF and BAF related to fish. Therefore, the water temperature T is 20 ℃, the dissolved oxygen in the water is 90%, and the water environment is maintained in a better state.

(2) Parameters relating to the biotoxicity of contaminants

Wherein, p and E_fThe values of (A) are mainly referred to data given by an AQUATOX model database (https:// www.epa.gov/cam/aqua) established by the U.S. environmental protection agency; w_BThe values of (a) are derived from a Fish base database (https:// www.fishbase.in/search. php); the value of L is mainly determined by OECD determinationAccording to the BCF and BAF experiment standards, the lipid content of fish is not greatly different, and the lipid content L of three species is 5%; the value of R is also referred to the standard of OECD determination BCF and BAF experiments, and the food intake of the BCF and BAF is controlled to be about 1 percent of the self wet weight in the feeding process of the aquatic organisms. And the value of the weber distribution range parameter m and the shape parameter n is taken according to the actual sensitivity distribution fitting result of the species.

(3) Lotka-Volterra model-related parameters

Finally, A, C and F can be understood as the intrinsic growth rate of the species corresponding to each of the three species, so that corresponding values can be obtained by searching the literature of the population quantity change and population growth rate of each species. B. D, E and G show the influence of interspecies predation effect on the population number of various species, but at present, the part has no clear reference value and can only be estimated according to the influence of the predation effect on the number of predators and predators. K₁、K₂And K₃The environmental capacity of each nutrition-grade species is respectively, and the parameters are related to the scale of the aquatic environment, so the values are taken in proportion, and the unit can be endowed according to the actual situation.

The parameter values for the subsequent simulation are summarized in table 5:

table 5 table of numerical simulation parameters of three group number dynamic models under influence of pollutants

Note: the population quantity is taken as a value in proportion, corresponding units can be given according to the size of an actual ecological system, and the time is in months;

s5.3, carrying out simulation on numerical simulation software

And (3) utilizing MATLAB programming to realize population quantity dynamic model simulation under the influence of organic pollutants, namely predicting population quantity change under the influence of the organic pollutants. The following variables can be changed in the simulation to observe different results of population quantity prediction:

(1) simulation time length: in general, the simulation duration is determined according to the time when the population quantity of a specific simulation result tends to be constant; or set according to the prediction requirement of the user.

(2) Concentration of contaminants in water: the method can be used for predicting different concentration conditions of pollutants in the water body.

The aquatic ecosystem has an example of the prediction result of the population quantity of food nets (midge-bluegill sunfish-largehead black bass) under the influence of PCBs:

(2.1) three population quantity change curves under the influence of a specific pollutant concentration

When the initial values of the three population numbers are set to [800000,800,80] and the contaminant concentrations are 0mg/L (dotted line) and 0.1mg/L, respectively, the population number change curves under the influence of the contaminants are shown in FIG. 4(a) and FIG. 4 (b):

from fig. 4(a) and 4(b), we can see that under this condition the population number of the first trophic class species decreases rapidly and then increases slowly to a constant value; the population number of the second trophic level species is slowly reduced to be constant; the population number of the third trophic class species slowly decreases to a constant number. In the presence of contaminants, the final constant values for the population numbers of the three species are less than in the absence of contaminants.

(2.2) three kinds of group quantity change curves under the influence of different pollutant concentrations

When the initial value of the three groups is set to [800000,800,80]]Changing the water body pollutant concentration C within the range of 0.01mg/L to 0.05mg/L_WThe number change curves of the first and second trophic species under the influence of the pollutants are shown in fig. 5-7, so that the number change trends of the first and second trophic species are not obviously changed along with the increase of the pollutant concentration, and the number of the third trophic species is changed from an increasing trend to a decreasing trend and finally still tends to a constant value. The final constant value of the population quantity of each trophic level species is continuously reduced along with the increase of the concentration of the pollutants in the water body, whereinThe final constant value of the third trophic level is zero.

It should be noted that the above-described embodiments may enable those skilled in the art to more fully understand the present invention, but do not limit the present invention in any way. Therefore, although the present invention has been described in detail with reference to the drawings and examples, it will be understood by those skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope of the invention.