CN106932538A - A kind of nickel ion is to the Forecasting Methodology of wheat root elongation toxicity and its application in soil - Google Patents

Abstract

The invention discloses a kind of nickel ion to the Forecasting Methodology of wheat root elongation toxicity and its application in soil, belong to ecological heavy metal toxicity evaluation areas.The present invention considers Ca²⁺Deng cation to the toxicity Competitive assays effect of nickel ion, and influence of the osmotic pressure effect to toxicity under edaphic condition is have modified, the poisonous effect of nickel is calculated while being calculated using visual MINTEQ programs and obtaining the activity of nickel ion.Determine that each cation suppresses parameter, the poisonous effect parameter of nickel form, osmotic pressure effect parameter to the bio-toxicity of nickel ion under the conditions of sand culture first, the parameter of acquisition can be used for prediction of the nickel ion to wheat root toxicity under soil type, this method is also applied for the prediction that nickel ion extends toxicity to other roots of the crop, can be that heavy metal-polluted soil ecological risk assessment and remediation contaminated soil provide reference.

Description

A kind of nickel ion is to the Forecasting Methodology of wheat root elongation toxicity and its application in soil

Technical field

The invention belongs to ecological heavy metal toxicity evaluation areas, more specifically to a kind of nickel ion to small in soil Wheat root extends the Forecasting Methodology of toxicity, extends the forecast model and ginseng of toxicity to wheat root using acquisition nickel ion under the conditions of sand culture Number, it is competitive on biomembrane part with heavy metal ion that this method had both considered cation, it is also considered that a large amount of sun in solution The osmotic pressure influence of ion, obtain parameter has good effect for predicting the root toxicity of nickel in soil type.

Background technology

Nickel contamination be due to excessive nickel and its compound into a kind of heavy metal pollution caused in environment, soil and The nickel of water body middle and high concentration can produce toxic action to animals and plants.Cereal crops can be right in the soil containing high concentration of nickel simultaneously Nickel has certain enrichment, and then is eaten, and finally influences human life and health.Wheat as one of big cereal in the world three, It is a kind of cereal crops worldwide planted extensively.So nickel for wheat toxicity prediction with estimate for planting industry There is extremely important meaning with environmental protection industry.

Heavy metal is existed with variform in soil, for different forms, its biological effectiveness and to plant The toxicity of growth is all different.Often can not completely just when being therefore estimated as quality standard using the total metal content of soil Really reflect heavy metal pollution and the bio-toxicity situation of soil.Research finds can be preferably using heavy metal available state concentration Prediction soil environment quality, the heavy metal free state (shape not being coordinated with organic or inorganic part wherein in the soil liquid State) activity be considered as having with phytotoxicity and directly contact；Additionally, in the soil liquid other cation coexists may be to freedom State heavy metal ion with competitive toxicity inhibition effect；Simultaneously under edaphic condition, brought by salinity in the soil liquid Osmotic pressure influence can also influence the biological effect of plant.Conditions above all should comprehensively give in model is set up and consider.It is in the past literary Offer on metal to the method more than the toxicity prediction method of plant using water planting, for example, Chinese Patent Application No. is 201610317197.0, Shen Qing Publication day is that the patent application document on October 12 in 2016 discloses nickel under the conditions of a kind of water planting The determination method of ion pair wheat root elongation toxicity and application, invention are individually controlled each cation concn using control variate method And change, step by step calculation goes out K⁺、Na⁺、Ca²⁺、Mg²⁺And H⁺Five kinds of cations are to the inhibitory action of nickel ion toxicity, while utilizing MINTEQ programs calculate Ni under the conditions of each²⁺And NiHCO₃ ⁺Amount calculate the poisonous effect of the two nickel forms, determine each sun The bio-toxicity of ion pair Ni suppresses parameter and two kinds of poisonous effect parameters of Ni forms, creates Ni under the conditions of water planting²⁺To small The determination method of wheat root toxicity.The result of study discloses Mg²⁺Presence Deng cation to nickel ion toxicity competes protective effect, because This must take in toxicity prediction model.But we study the toxicity for being further discovered that to obtain using above-mentioned ciltivating process Parameter occurs relatively large deviation when true soil environment is applied to, it is impossible to be completely suitable for soil environment, and at present on nickel pair The soil toxicity forecast model of wheat has not been reported.

The content of the invention

1. the problem to be solved

For existing heavy metal in soil methods of Toxicity Assessment there are problems that assessment it is not comprehensive, this hair It is bright that Forecasting Methodology and its application that a kind of nickel ion extends toxicity to wheat root in soil are provided, in the soil liquid, more often The a large amount of cations seen mainly have Ca²⁺、Mg²⁺And H⁺, while form of the nickel ion in the solution there may be bio-toxicity is main It is Ni²⁺.Wherein it is determined that each cation is to Ni²⁺Bio-toxicity suppress parameter, the poisonous effect parameter of nickel ion form and to ooze Pressure effect parameter is to set up key of the nickel ion to the determination method of wheat root elongation toxicity under the conditions of sand culture thoroughly.The present invention is based on Free ion activity model, the activity of each ion under different condition is calculated using visual MINTEQ programs, while considering not With competitive effect of the cation on biomembrane part, each cation concn is individually controlled and changed using control variate method, Obtain Ca²⁺、Mg²⁺And H⁺Three kinds of cations to the inhibitory action parameter of nickel ion toxicity, according to certain dose-effect relationship side Journey can predict Ni in sand²⁺To the poisonous effect of wheat root.Osmotic pressure is carried out simultaneously to wheat root toxotest, obtain solution from Sub- intensity and the docs-effect equation of wheat root elongation, using influence of the mode amendment osmotic pressure to Ni toxicity that act synergistically, build The vertical wheat root toxicity prediction equation suitable under edaphic condition.Obtained model is tested with actual earth culture toxicity test result Card, illustrates the validity of model.

2. technical scheme

In order to solve the above problems, the technical solution adopted in the present invention is as follows：

A kind of nickel ion extends the Forecasting Methodology of toxicity to wheat root in soil, comprises the following steps：

(1) toxicity tests design：

Breeding is carried out to wheat seed, selection chitting piece carries out toxicity tests, chitting piece is carried out into sand culture, controls Ion concentration in sand culture liquid processed, pair with nickel ion produce competitive effect cation Ca²⁺、Mg²⁺And H⁺Using control variate method, Under conditions of controlling the concentration of other cations constant while the concentration of certain cation is only changed, to wheat germination seed Carry out sand culture；

(2) wheat toxicity parameter is determined：

After toxicity test terminates, the root elongation of wheat under the conditions of different sand cultures is measured, calculate biological response value, accounting equation For：

Wherein, RE is biological response, L_iRepresent the root elongation of the wheat under nickel ion toxic effect, L_ckRepresent and L_iPhase The root elongation of the corresponding wheat without nickel ion toxic effect；

After obtaining RE values, then calculate corresponding EC under each cation concn₅₀It is worth, accounting equation is：

Wherein, C represents alignment processing group { Ni²⁺Activity, β is the form parameter of equation, the free state ion of each cation Activity is calculated by form software for calculation visual MINTEQ；According to EC₅₀With each cation Ca²⁺、Mg²⁺And H⁺Pass Toxicity tests data, it is determined that there is the cation of Competitive assays effect with nickel ion, non-thread are carried out using equation (3) by system Property fitting, obtain toxicity prediction model parameter f₅₀, β and K_XBL。

Corresponding EC₅₀Value can be calculated by below equation and obtained：

Wherein, { Ni²⁺}、{Ca²⁺}、{Mg²⁺And { H⁺Refer to the free state activity of each ion, K_XBLIt is that X ions are matched somebody with somebody with biology Binding constant (such as K of body_CaBLIt is the binding constant of Ca ions and bio-ligand, K_HBLIt is the combination of H ions and bio-ligand Constant etc. is by that analogy).The study find that for nickel ion, main competitiveness ion is Mg²⁺, i.e., equation (3) can be with letter Turn to below equation；

(3) the influence experiment of osmotic pressure：

Wheat root of the measurement under different salinity is long, and Ni is free of in exposure solution²⁺, correct molten using below equation Influence of the osmotic pressure to wheat root poisonous effect long in liquid：

Wherein I is the ionic strength of solution, β₀It is the form parameter of equation.Can be fitted using osmotic pressure toxicity test result Go out corresponding I₅₀And β₀；

(4) toxicity prediction model is built：

According to EC₅₀With each cation Ca²⁺、Mg²⁺And H⁺Relation, it is determined that there is the sun of Competitive assays effect with nickel ion Ion, and after going out osmotic pressure to toxic effect using osmotic pressure influence experimental calculation, it is believed that there is synergy between the two Toxicity Relationships (multiplication relationship), i.e., be modified using equation (6) to equation (5), can obtain nickel ion to small in different soils Wheat root elongation toxicity predictive equation be：

(5) earth culture confirmatory experiment method

To verify application effect of the toxicity parameter obtained under sand culture experiment condition in actual soil, this earth culture is devised Confirmatory experiment.About 18 kinds of collection National Representative soil, soil crosses 2mm sieves after air-drying, obtain different using artificial contaminating mode The contaminated soil of Ni concentration levels, balances 30 days after keep soil moisture content to be field capacity 80% that added water after contamination, adopts Wheat root elongation experiment is carried out with identical toxicity tests method is tested with sand culture, period is micro using the soil liquid The soil liquid of liquid device (Rhizon MOM) in-situ acquisition about 5mL is adopted, Ni in solution ph, total organic carbon TOC, solution is determined²⁺、 Mg²⁺、Na⁺、K⁺、Ca²⁺、Cl^-、NO₃ ^-、SO₄ ^2-Concentration, calculates and obtains solution ion strength, and wherein TOC represents fulvic acid FA contents, Each ionic activity is calculated by form software for calculation visual MINTEQ, using the toxicity of nickel in equation (7) prediction corresponding soils Effect.During using this model, can be without carrying out toxotest, directly the collection soil liquid simultaneously determine related component, The toxicity parameter obtained using equation (7) and the present invention carries out toxicity prediction calculating.

Further, using sand culture, rather than water planting mode extends come nickel ion in predicting actual soil to the root of wheat Toxicity.

Further, the dominant cation that there is Competitive assays effect with nickel ion is determined using method in step (2) It is Mg²⁺, basic toxicity prediction equation is set up using equation (7) and crucial toxicity parameter is obtained, while being corrected using equation (7) The influence that osmotic pressure is produced to toxicity；

Further, the input data of described form software for calculation visual MINTEQ includes pH value, all ions With the total concentration of part, system is set to open system, i.e., with CO in air₂Balance.

Further, the Forecasting Methodology of the poisonous effect that nickel ion extends to wheat root is：Know sand culture solution system In each total ion concentration, { Ni under the conditions of this is calculated by form software for calculation visual MINTEQ²⁺}、{Mg²⁺Activity, profit The poisonous effect that nickel ion extends to wheat root under the conditions of this is predicted with equation (7).

A kind of above-mentioned nickel ion is to the Forecasting Methodology of wheat root elongation toxicity in soil in heavy metal toxicity evaluation areas In application.

A kind of Forecasting Methodology answering in wheat planting field of the above-mentioned nickel ion to wheat root elongation toxicity in soil With.

The invention provides the poisonous effect parameter that heavy metal nickel ion pair wheat root is obtained under the conditions of a kind of use sand culture, Nickel extends the determination method of toxicity to wheat root in for predicting soil, and establishes the biochemistry ginseng of complete models fitting Number.

The concentration referred in the present invention is the amount of solute in solution, is represented with [] or c；And activity refers to effects of ion reality The valid density that border plays a role, is represented with { } or α.Relation between the two is c=γ α, and wherein γ is activity coefficient.

The soil liquid is the part of plant root most directly contact, and nickel can to the toxic action of wheat root in the soil liquid To be modeled as number of the nickel in wheat root binding sites, cation Ca at the same time common in the soil liquid²⁺、Mg²⁺And H⁺ The point position that can be combined with nickel competition wheat root is likely to, so as to suppress the root toxicity of nickel.

Toxicity Computing Principle is as follows：

The active site position of plant root is modeled as part, and the toxicity response of plant is changed into heavy metal and ligand binding The percentage (f) of point position represent that therefore the measuring effect relation of toxicity can be expressed as：

Here f₅₀Refer to that total part point position of plant generates 50% biological inhibition toxicity effect after being combined by nickel ion Seasonable heavy metal and the percentage of the point position of ligand binding.

When concentration is relatively low, competitive cation (Ca²⁺、Mg²⁺And H⁺) it is considered as nontoxic to wheat, and they can Bio-ligand point position is competed so as to reduce nickel ion to wheat root toxicity with nickel ion.Total point position (TBL) can be expressed as：

[TBL]=[BL^-]+[NiBL⁺]+[CaBL⁺]+[MgBL⁺]+[HBL] (9)

Wherein, [BL^-] represent biological the point position, [NiBL not combined by cation⁺] represent by Ni²⁺With reference to biological point Position, [CaBL⁺] represent by Ca²⁺With reference to biological point position, [MgBL⁺] represent by Mg²⁺With reference to biological point position, [NaBL] represents quilt Na⁺With reference to biological point position, [KBL] is represented by K⁺With reference to biological point position, [HBL] is represented by H⁺With reference to biological point position.

So Ni²⁺Percentage (f) with the point position of ligand binding can be expressed as：

Wherein, { Ni²⁺}、{Ca²⁺}、{Mg²⁺And { H⁺Refer to the free state activity of each ion, K_XBLIt is that each ion is matched somebody with somebody with biology The binding constant of body, bringing equation (10) into equation (8), can to calculate biological response (RE) as follows：

If (f when f is in 50% biological inhibition poisonous effect₅₀), equation (10) can be changed into：

Wherein, EC₅₀Refer to produce 50% biological inhibition poisonous effect when solution in Ni²⁺Activity.

When a large amount of cation concns are higher, its osmotic pressure depression effect for producing cannot just be ignored, and add osmotic pressure shadow Ring after calculating, after corrected Calculation result, nickel ion is to the accounting equation of wheat root elongation toxicity：

Above equation is Ni toxic models fitting framework, wherein RE and EC₅₀Toxic degrees of the Ni to wheat is represented, Model parameter (f₅₀、I₅₀、β、β₀And K_XBL) can be carried out by using toxicity tests data and DAS it is non-linear Fitting minimizes root-mean-square error (RMSE) and obtains, and finally sets up Ni under the conditions of complete sand culture²⁺To wheat root elongation toxicity Determine method.

Specifically technical step is：

The first step：The sand culture toxicity tests design of wheat root elongation

For three cation (Ca of generation competitive effect²⁺、Mg²⁺And H⁺) control variate method is used, only change certain sun Control the concentration of other cations constant while the concentration of ion, each treatment group carries out three repetitions and tests.Before experiment Breeding need to be carried out to wheat seed, specific breeding method is as follows：To clean and sterilized wheat seed, be equably placed on By in the culture dish containing filter paper of ultrapure water-soaked, culture dish is positioned in growth cabinet carries out breeding.Climate box Ambient parameter is 20 DEG C of temperature, air humidity 80%, no light, and breeding continues 48h, and culture dish is kept during breeding Interior filter paper moistening.After the completion of 48h breedings, select Germinating status good and seed that is there are three be about 1cm short is given birth to Thing toxicity test.

The seed that five are chosen is planted on quartz sand in toxicity tests, quartz sand is for analysis is pure, cross 16 mesh sieves And it is treated with watery hydrochloric acid.Whole toxicity test is carried out in growth cabinet, and the setting of growth cabinet environmental condition is as follows： The time is 16 hours daytime, 8 hours nights round the clock；25 DEG C of daytime temperature, air humidity 75%；20 DEG C of night temperature, air is wet Degree 85%.The toxicity test time is 7 days, and wheat is harvested when reaching toxic endpoints.

Second step：Determine wheat toxicity parameter and calculate each ionic activity in solution

After toxicity tests reach toxic endpoints, the root elongation of wheat in each treatment group, wheat root extension measurement are measured It is as follows：Three root records most long are one plant of root elongation situation of wheat in every plant of wheat root of selection.The corresponding life of each treatment group Thing response (RE) be calculated as follows for：

Wherein L_iRepresent the root elongation of the wheat under Ni toxic effects, L_ckRepresent and L_iCorresponding does not have Ni toxic effects Wheat root elongation.After calculating there emerged a the corresponding biological response for the treatment of group (RE), using bio-toxicity measuring effect relation Equation (equation (2)) calculates corresponding EC under each cation concn₅₀Value.

Wherein C represents alignment processing group { Ni²⁺Activity, β is the form parameter of equation.

The free state ionic activity of each cation is calculated using free form software for calculation visual MINTEQ, and this is soft The input data of part includes the total concentration of pH value, all ions and part, and system is set to open system, i.e., with CO in air₂ Balance.

3rd step：Build toxicity prediction model

According to EC₅₀With each cation (Ca²⁺、Mg²⁺And H⁺) relation, it is determined that and Ni²⁺There is the cation of competitive effect, It is a discovery of the invention that { Ni²⁺Poisonous effect is shown to wheat root elongation, while in five kinds of cations, only { Mg²⁺Can be to nickel Toxicity produces linear Competitive assays effect, and toxicity tests data are carried out using DAS using equation (5) Nonlinear fitting, is aided with the calculating that a large amount of cation permeabilities press depression effect, can obtain toxicity prediction model parameter (f₅₀、I₅₀、 β、β₀And K_XBL), as shown in Tables 1 and 2.Finally set up the accounting equation that nickel under the conditions of complete sand culture extends toxicity to wheat root And biochemical parameters.

1. sand culture of table Ni under the conditions of 7 days²⁺The biochemical parameter of poisonous effect is extended to wheat root

A) unit of K is L/mol, NM other cation (K in table⁺、Na⁺、H⁺、Ca²⁺) K values be 0；

b)R²(coefficient of determination) and RMSE (root-mean-square error) represent the fit solution of fit procedure result.

The biochemical parameter of 2. sand culture of table cation permeability pressure effect under the conditions of 7 days

a)R²(coefficient of determination) and RMSE (root-mean-square error) represent the fit solution of fit procedure result.

4th step：The application of toxicity prediction model

In known any Sand culture under conditions of each total ion concentration, this is calculated by visual MINTEQ equations Under the conditions of { Ni²⁺}{Mg²⁺Activity, while the ionic strength in overall solution is calculated, using the parameter of table 1 and 2, substitution side Journey (7), you can realize prediction poisonous effect for being extended to wheat root of nickel under the conditions of this.

3. beneficial effect

Compared to prior art, beneficial effects of the present invention are：

(1) present invention solves Ni under edaphic condition²⁺To wheat root toxicity cannot Accurate Prediction problem, considering Ni²⁺Toxicity and competitive cation on the basis of, while have modified influence of the osmotic pressure to toxicity, determine each cation to Ni Bio-toxicity suppress the affecting parameters of parameter and osmotic pressure, create Ni under the conditions of sand culture²⁺To the determination side of wheat root toxicity Method, the result of acquisition can be used for Ni under the conditions of earth culture²⁺Prediction to wheat root toxicity, be heavy metal-polluted soil ecological risk assessment and Remediation contaminated soil provides reference；

(2) advantage of the invention is that the Ni obtained under the conditions of sand culture²⁺Prediction Parameters to wheat root toxicity can be used directly In earth culture experiment, it is achieved thereby that Ni in prediction different soils²⁺To the purpose of wheat root toxicity, while experimental technique can be used for it The root toxicity prediction of his similar crop；

(3) innovative point of the invention is to have considered nickel fractions and concentration, competitive cation and osmotic pressure effect Tackle the influence of wheat root toxicity；

(4) method that the present invention is provided can consider soil nickel concentration, complex ion, competing ions, osmotic pressure etc. Many factors, obtain toxicity parameter by polytype true soil checking effectively reliability, are the plant of heavy metal in soil Toxicity assessment provides direct method；

(5) present invention is proposed to carry out toxotest using sand culture mode, and poisonous effect to osmotic pressure is corrected, institute The toxicity prediction model for obtaining verified on National Representative soil, obtains better result.

Brief description of the drawings

Fig. 1 for the present invention in each cation to 7 days Ni²⁺The EC of wheat root toxicity₅₀Influence figure (wherein each figure generation respectively Refer to that cation is as follows：Ca²⁺(A)、Mg⁺And H (B)⁺(C)；Each figure ordinate represents 7 days Ni²⁺Wheat root toxicity EC₅₀, abscissa table Show the activity of each cation in Hydroponic Solution, wherein Mg²⁺To Ni²⁺The EC of toxicity₅₀Influence it is more obvious, pretend linear point Analysis)；

Fig. 2 be cation permeability pressure influence fitted figure (when various Common Cations change in solution, effects of ion intensity Meet dose-effect relationship with growth inhibition situation with wheat；Ordinate represents 7 days cation permeability pressures to wheat root in figure Suppress, abscissa represents the ionic strength in solution)；

Fig. 3 is that (with the experiment of actual earth culture for confirmatory experiment group, 18 kinds of sampling soils are in the whole nation for collecting soil sample distribution map Distribution situation as scheme)；

Fig. 4 is that (figure A is only to use for comparing figure between the biological response result that two kinds of toxicity calculations are obtained in the present invention Ni in Sand culture solution²⁺Activity earth culture toxicity data is carried out as toxicity considerations, i.e. Free ion activity model FIAM The calculating that fitting obtains model predicts the outcome；Figure B is that the model parameter calculation obtained using determination method of the invention predicts knot Really.Wherein A and B are the comparings of the result of calculation in earth culture experiment.The ordinate of two figures is the biological response of model prediction, Abscissa is the biological response for actually observing, and RMSE in figure is between model prediction result and actual observation result Root-mean-square error, r is the coefficient correlation between model prediction result and actual observation result, and solid line represents 1 in two figures:1 Line, dotted line is represented relative to 1:1 deviation of unit of 1 line).

Specific embodiment

The present invention is further described below with reference to specific embodiment.

Embodiment 1

For three cation (Ca of generation competitive effect²⁺、Mg²⁺And H⁺) control variate method is used, only change certain sun Control the concentration of other cations constant while the concentration of ion, each treatment group carries out three repetitions and tests.Each treatment group The ion component of sand culture solution is shown in Table 3 and 4.Breeding is carried out before experiment to wheat seed, specific breeding method is as follows：Will cleaning Cross and sterilized wheat seed, be equably placed on by the culture dish containing filter paper of ultrapure water-soaked, culture dish is put Being placed in carries out breeding in growth cabinet.The ambient parameter of climate box is 20 DEG C of temperature, air humidity 80%, no light, breeding Continue 48h, and to keep filter paper in culture dish to moisten during breeding.After the completion of 48h breedings, selection Germinating status are good simultaneously And the seed for having three be about 1cm short carries out toxicity tests.

The seed that five are chosen is planted on quartz sand in toxicity tests, quartz sand is for analysis is pure and uses dilute salt It is acid-treated.Whole toxicity test is carried out in growth cabinet, and the setting of growth cabinet environmental condition is as follows：Round the clock the time be 16 hours daytime, 8 hours nights；25 DEG C of daytime temperature, air humidity 75%；20 DEG C of night temperature, air humidity 85%.Toxicity Experimental period is 7 days, and wheat is harvested when reaching toxic endpoints.

Ion components of the table 3.Ni to each treatment group sand culture solution in the experiment of wheat root toxicity sand culture

Ion component of the osmotic pressure of table 4. to each treatment group sand culture solution in the experiment of wheat root toxicity sand culture

After toxicity tests reach toxic endpoints, the root elongation of wheat in each treatment group, wheat root extension measurement are measured It is as follows：Three root records most long are one plant of root elongation situation of wheat in every plant of wheat root of selection.The corresponding life of each treatment group Thing response (RE) be calculated as follows for：

Wherein L_iRepresent the root elongation of the wheat under Ni toxic effects, L_ckRepresent and L_iCorresponding does not have Ni toxic effects Wheat root elongation.According to equation (1) and the elongation of the wheat root of measurement, the corresponding biological response for the treatment of group being calculated (RE) value is as shown in Table 5 and 6；Then each cation is calculated using bio-toxicity measuring effect relation equation (equation (2)) Corresponding EC under concentration₅₀Value

Wherein C represents alignment processing group { Ni²⁺Activity, β is the form parameter of equation.Wherein β and EC₅₀Value passes through In the case of the data of known RE% and C, with equation (2) as Computational frame, it is calculated with nonlinear fitting.Each cation Free state ionic activity calculated using free form software for calculation visual MINTEQ, the input data of the software includes The total concentration of pH value, all ions and part, system is set to open system, i.e., with CO in air₂Balance.Each treatment group correspondence L_i、L_ck、RE、C、EC₅₀With β value such as table 5 below and 6：

Relevant parameters of the table 5.Ni to each treatment group in the experiment of wheat root toxicity sand culture

a.H⁺It is pH value, Ca that group is corresponding²⁺、Mg²⁺It is concentration, unit that group is corresponding：mM

Relevant parameter of the osmotic pressure of table 6. to each treatment group in the experiment of wheat root toxicity sand culture

a.Ca²⁺、Mg²⁺、Na⁺、K⁺It is concentration, unit that group is corresponding：mM

Wheat (poplar wheat No. 13) is by after breeding, toxotest 7 days, as a result finding there was only Mg²⁺Exist to nickel toxicity linear Competitive effect (Fig. 1), competing ions and nickel root toxicity EC₅₀Relation equation be respectively：

EC₅₀=0.0668 { Mg²⁺}+0.0797 (14)

Wherein, EC₅₀Unit be mM, { Mg²⁺Unit be mM.

Under the conditions of being calculated respectively using visual MINTEQ, the free state activity of each ion in system, using equation (3) (4) toxicity tests data are carried out with nonlinear fitting using DAS, fitting result finds, { Ni²⁺And it is a large amount of Cation permeability pressure is acted on and shows poisonous effect to wheat root elongation (see Fig. 2), while in five kinds of cations, only {Mg²⁺Competitive assays effect can be produced to nickel toxicity.Toxicity prediction model parameter (f is obtained when drawing up a contract₅₀、I₅₀、β、β₀With K_XBL), as shown in Tables 1 and 2.

To verify the reliability of proposition method of the present invention, serial earth culture experiment is separately carried out and has removed checking fitting parameter in reality Usable condition in soil pot experiment.Selected soil picks up from national 18 different places in soil pot experiment, Soil labile organic matter difference is larger, and with very strong representativeness, the soil of collection is shown in Fig. 3, the base of soil in national distribution situation This physicochemical property is shown in Table 7.Confirmatory experiment result is as shown in figure 4, show that the method and parameter prediction are functional.Knot is predicted simultaneously Fruit will be much better than and traditional only consideration { Ni²⁺Predicting the outcome for toxic ion.

7. ten eight kinds of physiochemical properties of soil of table

Claims (9)

1. a kind of nickel ion extends the Forecasting Methodology of toxicity to wheat root in soil, comprises the following steps：

(1) toxicity tests design：

Breeding is carried out to wheat seed, selection chitting piece carries out toxicity tests, chitting piece is carried out into sand culture, controls sand Training liquid in ion concentration, pair with nickel ion generation competitive effect cation Ca²⁺、Mg²⁺And H⁺Using control variate method, only Under conditions of controlling the concentration of other cations constant while the concentration for changing certain cation, wheat germination seed is carried out Sand culture；

(2) wheat toxicity parameter is determined：

After toxicity test terminates, the root elongation of wheat under the conditions of different sand cultures is measured, calculate biological response value, accounting equation is：

$RE\%=\frac{L_i}{L_{ck}}\×100---\left(1\right)$

Wherein, RE is biological response, L_iRepresent the root elongation of the wheat under nickel ion toxic effect, L_ckRepresent and L_iIt is corresponding The wheat without nickel ion toxic effect root elongation；

After obtaining RE values, then calculate corresponding EC under each cation concn₅₀It is worth, accounting equation is：

$RE\%=\frac{100}{1+{\left(\frac{C}{EC50}\right)}^{\mathrm{\β}}}---\left(2\right)$

Wherein, C represents alignment processing group { Ni²⁺Activity, β is the form parameter of equation, the free state ionic activity of each cation It is calculated by form software for calculation visual MINTEQ；According to EC₅₀With each cation Ca²⁺、Mg²⁺And H⁺Relation, really There is the cation of Competitive assays effect in fixed and nickel ion, Nonlinear Quasi is carried out to toxicity tests data using equation (3) Close, obtain toxicity prediction model parameter f₅₀, β and K_XBL；

$RE\%=\frac{100}{1+{\left(\frac{K_{NiBL}\left\{{\mathrm{Ni}}^{2+}\right\}}{f_{50}(1+K_{NiBL}\{{\mathrm{Ni}}^{2+}\}+K_{CaBL}\{{\mathrm{Ca}}^{2+}\}+K_{MgBL}\{{\mathrm{Mg}}^{2+}\}+K_{HBL}\{H^{+}\left\}\right)}\right)}^{\mathrm{\β}}}---\left(3\right)$

Corresponding EC₅₀Value can be calculated by below equation and obtained：

${\mathrm{EC}}_{50}=\frac{f_{50}}{(1-f_{50})K_{NiBL}}(1+K_{CaBL}\{{\mathrm{Ca}}^{2+}\}+K_{MgBL}\{{\mathrm{Mg}}^{2+}\}+K_{HBL}\{H^{+}\left\}\right)---\left(4\right)$

Wherein, { Ni²⁺}、{Ca²⁺}、{Mg²⁺And { H⁺Refer to the free state activity of each ion, K_XBLIt is the knot of X ions and bio-ligand Close constant；For nickel ion, main competitiveness ion is Mg²⁺, i.e. equation (3) can be reduced to below equation (5)；

$RE\%=\frac{100}{1+{\left(\frac{K_{NiBL}\left\{{\mathrm{Ni}}^{2+}\right\}}{f_{50}(1+K_{NiBL}\{{\mathrm{Ni}}^{2+}\}+K_{MgBL}\{{\mathrm{Mg}}^{2+}\left\}\right)}\right)}^{\mathrm{\β}}}---\left(5\right)$

(3) the influence experiment of osmotic pressure：

Wheat root of the measurement under different salinity is long, and Ni is free of in exposure solution²⁺, using in below equation calibration solution Influence of the osmotic pressure to wheat root poisonous effect long：

$RE\%=\frac{1}{1+{\left(\frac{I}{I_{50}}\right)}^{{\mathrm{\β}}_0}}---\left(6\right)$

Wherein I is the ionic strength of solution, β₀It is the form parameter of equation；Phase can be fitted using osmotic pressure toxicity test result The I for answering₅₀And β₀；

(4) toxicity prediction model is built：

According to EC₅₀With each cation Ca²⁺、Mg²⁺And H⁺Relation, it is determined that there is the cation of Competitive assays effect with nickel ion, And after using osmotic pressure influence experimental calculation going out osmotic pressure to toxic effect, it is believed that the toxicity that there is synergy between the two is closed System, i.e., be modified using equation (6) to equation (5), can be obtained nickel ion and be extended the pre- of toxicity to wheat root in different soils Surveying equation is：

$RE\%=\frac{100}{1+{\left(\frac{K_{NiBL}\left\{{\mathrm{Ni}}^{2+}\right\}}{f_{50}(1+K_{NiBL}\{{\mathrm{Ni}}^{2+}\}+K_{MgBL}\{{\mathrm{Mg}}^{2+}\left\}\right)}\right)}^{\mathrm{\β}}}\×\frac{1}{1+{\left(\frac{I}{I_{50}}\right)}^{{\mathrm{\β}}_0}}---\left(7\right).$

2. a kind of nickel ion according to claim 1 extends the Forecasting Methodology of toxicity to wheat root in soil, and its feature exists In：Toxicity is extended to the root of wheat come nickel ion in predicting actual soil using sand culture, rather than water planting mode.

3. a kind of nickel ion according to claim 1 and 2 extends the Forecasting Methodology of toxicity, its feature to wheat root in soil It is：Method determines that the dominant cation that there is Competitive assays effect with nickel ion is Mg in using step (2)²⁺, using equation (7) set up basic toxicity prediction equation and obtain crucial toxicity parameter, while osmotic pressure is corrected using equation (7) being produced to toxicity Raw influence.

4. a kind of nickel ion according to claim 1 extends the Forecasting Methodology of toxicity to wheat root in soil, and its feature exists In：The input data of described form software for calculation visual MINTEQ includes the total concentration of pH value, all ions and part, System is set to open system, i.e., with CO in air₂Balance.

5. a kind of nickel ion according to claim 1 extends the Forecasting Methodology of toxicity to wheat root in soil, and its feature exists In：The Forecasting Methodology of the poisonous effect that nickel ion extends to wheat root is：Know each total ion concentration in sand culture solution system, lead to Cross form software for calculation visual MINTEQ and calculate { Ni under the conditions of this²⁺}、{Mg²⁺Activity, predict this using equation (7) The poisonous effect that nickel ion extends to wheat root under part.

6. a kind of nickel ion described in claim 1 is commented the Forecasting Methodology of wheat root elongation toxicity in soil in heavy metal toxicity Estimate the application in field.

7. a kind of nickel ion described in claim 1 extends the Forecasting Methodology of toxicity to wheat root in soil in wheat planting field In application.

It is 8. a kind of to predict the model equation that nickel ion extends toxicity to wheat root in soil, it is characterised in that：Described model side Cheng Wei：

$RE\%=\frac{100}{1+{\left(\frac{K_{NiBL}\left\{{\mathrm{Ni}}^{2+}\right\}}{f_{50}(1+K_{NiBL}\{{\mathrm{Ni}}^{2+}\}+K_{MgBL}\{{\mathrm{Mg}}^{2+}\left\}\right)}\right)}^{\mathrm{\β}}}\×\frac{1}{1+{\left(\frac{I}{I_{50}}\right)}^{{\mathrm{\β}}_0}}$

Wherein, { Ni²⁺And { Mg²⁺Refer to the free state activity of each ion, K_XBLIt is the binding constant of X ions and bio-ligand；I is The ionic strength of solution, β₀It is the form parameter of equation (6), f₅₀It is prediction model parameterses.

9. a kind of method that nickel ion verified described in claim 1 extends the Forecasting Methodology of toxicity to wheat root in soil, It is characterised in that it includes following steps：About 18 kinds of collection National Representative soil, soil crosses 2mm sieves after air-drying, using artificial dye Malicious mode obtains the contaminated soil of different Ni concentration levels, and it is the 80% of field capacity to be added water after contamination and keep soil moisture content Afterwards balance 30 days, using with claim 1 in test identical toxicity tests method carry out wheat root elongation experiment, Period using the micro soil liquid for adopting liquid device (Rhizon MOM) in-situ acquisition about 5mL of the soil liquid, determines solution ph, total Ni in Organic Carbon TOC, solution²⁺、Mg²⁺、Na⁺、K⁺、Ca²⁺、Cl^-、NO₃ ^-、SO₄ ^2-Concentration, calculates and obtains solution ion strength, wherein TOC represents fulvic acid FA contents, and each ionic activity is calculated by form software for calculation visual MINTEQ, pre- using equation (7) Survey the poisonous effect of nickel in corresponding soils.