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    • 专利摘要:
    The invention is related to the field of heavy metal ecotoxicity assessment, and in particular to a method for predicting toxicity of tungsten to wheat root elongation. 2- - - 2- Complexing stability constants of WO4 , HWO4 , H2PO4 , and SO4 for the wheat root 5 ligand are estimated based on BLM so as to establish the BLM adapted to predict toxicity 2- - - of W(IV) to wheat. After determining concentrations of WO4 , HWO4 , H2PO4 , and 2- SO4 in a soil for growing wheat, values thereof are substituted into the established BLM so as to predict toxicity of W(IV) to wheat root elongation. According to the method, 2- - - 2- WO4 and HWO4 are regarded as toxic forms of W(IV), and H2PO4 and SO4 are 10 regarded as competitors for binding to the wheat root ligand. The method takes into account the competition between the W(IV) forms and coexisting anions. In this way, the prediction accuracy of the toxicity of W(IV) to wheat root elongation can be significantly improved.
    公开号:NL2027968A
    申请号:NL2027968
    申请日:2021-04-14
    公开日:2021-07-30
    发明作者:Li Shaojing；Che Guangjie
    申请人:Univ Qingdao Agricultural；
    IPC主号:
    专利说明:

    METHOD FOR PREDICTING TOXICITY OF TUNGSTEN TO WHEAT ROOT
    ELONGATION BY USING BIOTIC LIGAND MODEL Technical Field The present invention is related to the field of heavy metal ecotoxicity assessment, and in particular to a method for predicting toxicity of tungsten to wheat root elongation. Background The wide use of tungsten (W(VI)) has caused environmental pollution. In particular, dissolution of metallic tungsten powder may lead to acidified water and cause concentration of dissolved oxygen therein to be lowered. This may cause soil properties to be varied and migration and transformation capabilities of other heavy metals to be enhanced. It has been reported that, when the particle size of the tungsten powder is about 5 um, the critical tungsten concentration at which the tungsten metal can have obvious harmful consequences for the environment is around 1 %. Once the concentration of tungsten present in soil reaches or exceeds this value, undesirable results may be caused, which include soil acidification, increased release of dioxide carbon (CO:), reduction of organic carbon content and of the ability to decompose organic matter, and inhibited growth of biological communities and of ryegrass and even death thereof. It is known that tungsten is present in water body and soil as single compounds and multiple complexes, such as, polyoxotugstate. Tungsten has multiple oxidation states, and tends to form poly-tungstates in a water body having a low pH level and a high tungsten concentration. The poly-tungstates have a higher grade toxicity and may coexist with single tungsten compounds. Currently, W(VI) migration in the environment and the ecotoxicological mechanism thereof have not yet been discussed sufficiently, and possible ecotoxic effects of W(VT) on the environment are rarely reported. Summary In view of the above problems, an objective of the invention is to provide a method for predicting toxicity of W(IV) to wheat root elongation, which makes possible an accurate prediction of the toxicity of W(IV) to wheat root elongation.
    Accordingly, an objective of the invention is realized by a method for predicting toxicity of W(IV) to wheat root elongation, comprising steps of: a. determining concentrations of WO4*, HWO:, H:PO, and SO4* in a soil for growing wheat, with the concentrations being expressed in the same unit; and 5b. substituting the determined values of the WO, HWOr, HoPO:, and SO: concentrations into Formula (I) to calculate relative root elongation; 100 of Kyo, zi WO }+ Kimo: (Ho: } oe | | fom 1 + Kom WO: - i+ Kian: HO: i+ Ky ron HPO: i+ Kon 505 i Formula (I) {5% where, RE represents the relative root elongation, "2: =024-036; B=1.92-2.06; logKyos.=4.05-4.11; logKrwo481=6.39-6.49, logKa2p0431=2.00-2.18, logKsous=1.70-
    2.04; and, {WO}, {HWO:}, {H2POy}, and {$SO: } represent the determined vales of the WO:”, HWOr, HoPO-, and SO4” concentrations, respectively.
    In a preferred embodiment, the step (b) further comprises: substituting the determined values of the WO”, HWOr, HoPOr, and SO concentrations, obtained in the step (a), into Formula (II) to calculate EC50 of WO4*" on wheat root system; and substituting the determined values of the WO4*, HWOr, H;POr, and SOs concentrations, obtained in the step (a), into Formula (III) to calculate EC50 of HWO- on wheat root system; 50% _ fe 2- | f 4 } Jon {1 + Kopo BE [H,PO,; jn Kos WO; h EC50WO |= — TR en wo, | 1 for | Aro: + K yon or Formula (II) 500 > { “1, Pa Sea A+ K WPO, (+ Kp 3807 } ECSO{HWO, |= Lo oT 50% > | aj ( = Jaa. [ K H¥WC,BL + Koos: wo. Formula (IIT) 30% in the formulas (II) and (III), is =0.30; logKrose:=4.08, logKuwosr=6.44, logKr2r0481=2.09; logKsos:=1.87; and, (W042), {HWOy}, {HPO}, and {S04}
    represent the determined values of the WO:%, HWO-, HaPO-, and SO4* concentrations, respectively. In a preferred embodiment, the wheat variety comprises Jimai 22, Jimai 23, Jimai 44 and Yanmai 1212.
    The present invention provides a method for predicting toxicity of W(IV) to wheat root elongation, which is based on the Biotic Ligand Model (BLM). According to the method, complexing stability constants of WO4*, HWOr, HsPOr, and SO:* for the wheat root ligand are estimated based on BLM so as to establish the BLM adapted to predict the toxicity of W(IV) to wheat. After determining the concentrations of WO:%, HWOr, HyPOy, and SO4*" in the soil for growing wheat, values thereof are substituted into the established BLM so as to predict the toxicity of W(IV) to wheat root elongation. According to the method, WO and HWO are regarded as toxic forms of W(IV), and H;PO- and SO are regarded as competitors for binding to the wheat root ligand. Thus, the method takes into account the competition between the W(IV) forms or species and coexisting anions. In this way, the prediction accuracy of the toxicity of W(IV) to wheat root elongation can be significantly improved. According to the method, further, formulas for calculating EC50 of WO on wheat root system and for calculating EC50 of HWO: on wheat root system are obtained based on the established BLM for predicting the toxicity of W(IV) to wheat. It has been found that the EC50 values predicted by the method are within 2 times the measured values. Therefore, the method of the invention can provide high-accuracy prediction.
    Brief Description of the Drawings FIG. 1 shows the procedures in Example 1 in a flowchart; FIG. 2 shows distribution of various W(VI) forms at different pH levels; FIG. 3 illustrates relationships between OH activity and EC50{WO:}, and between OH activity and EC50{HWO:t; FIG. 4 illustrates a correlation between EC50{WO:} and HWOr/WO:*; FIG. 5 illustrates a correlation between EC50{WO. } and CaWO*/WO: ; FIG. 6 illustrates a relationship between EC50{WO4} and HaPO:; FIG. 7 illustrates a relationship between EC50{HWO:'} and H:PO:; FIG. 8 illustrates a relationship between EC50{WO4 } and SO:4% activity; FIG. 9 illustrates a relationship between EC50{HWO:"} and SO: activity;
    FIG. 10 illustrates a relationship between predicted EC50{HWQO4} and measured EC50{HWOy}, where the dashed line indicates a good agreement therebetween and solid lines indicates the predicted EC50{HWO:} within 2 times the measured EC50{HWO:3;
    S FIG. 11 illustrates a relationship between predicted EC50{WO: } and measured EC50{WO0.*}, where the dashed line indicates a good agreement therebetween and solid lines indicates the predicted EC50{WO4*"} within 2 times the measured EC50{WO4>}: FIG. 12 illustrates a relationship between WO activity and measured wheat root lengths;
    FIG. 13 illustrates a relationship between predicted values of wheat root lengths and measured values thereof, obtained through free ion activity model for WO:”; FIG. 14 illustrates a relationship between HWO- activity and measured wheat root lengths; FIG. 15 illustrates a relationship between predicted values of wheat root lengths and measured values thereof, obtained through free ion activity model for HWO:; FIG. 16 illustrates a relationship between partition coefficient based on the BLM theory and measured wheat root lengths; and FIG. 17 illustrates a relationship between predicted values of wheat root lengths obtained through the BLM theory and measured values thereof.
    In FIGS. 12 to 17, the dashed lines indicate a very good agreement between predicted values and measured values, and the solid lines show a predication curve.
    Detailed Description The present invention provides a method for predicting toxicity of W(IV) to wheat root elongation, comprising steps of: a. determining concentrations of WO:%, HWOr, H:PO:, and SO in a soil for growing wheat, with the concentrations being expressed in the same unit; and b. substituting the determined values of the WO, HWOr, H;POr, and SO:” concentrations, obtained in the step (a), into Formula (I) to calculate relative root elongation;
    RE = - 0; | Kou WO Kou WO} | | | fol + Kio WOS [+ K yy WO} Ky py 0 (HPO }+ Kg SO 3} Formula (I) where, RE represents the relative root elongation; fist =0.24-0.36;, B=1.92-2.06; 5 logKwoupi=4.05-4.11; logÄmros8=6.39-6.49; logKn2r048:=2.00-2.18; logKsosmi=1.70-
    2.04; and, {WO*}, {HWO:}, {H2POy}, and {S047} represent the determined vales of the WO”, HWO:, H:PO, and SO4 concentrations, respectively. According to the method, the concentrations of WO:>, HWO:, H:PO:, and SO4% in a soil for growing wheat are first determined, with the concentrations being expressed in the same unit. Preferably, the wheat variety comprises Jimai 22, Jimai 23, Jimai 44 and Yanmai 1212. Further, after the concentrations of WO”, HWOr, H;PO:, and SO4 are determined, the determined values thereof are substituted into a model as shown in Formula (I) to calculate relative root elongation; RF = EE ol Kyo WOP 4 Kaan EVO | | y TENT R aaa FO T+ K waat FIO 1K yp 1.0L [+ Ko (507) Formula (I) where, RE represents the relative root elongation; Sint =0.24-0.36;, B=1.92-2.06; logKwo48:=4.05-4 11; logKuno451=6.39-6.49; logK2r048:=2.00-2.18; logKso48=1.70-
    2.04, preferably, Lest =0.30; B=1.99; logKwosus=4.08; logKmromnr=6.44, logKero:81=2.09; logKsom=1.87, and, {WO}, {HWO:}, {HoPOr}, and {SO:#} represent the determined vales of the WO”, HWOr, HPO, and SO4* concentrations, respectively, take for example, Kon WOP} means that Krozs is multiplied with {WOR}. Preferably, after the concentrations of WO4>, HWOr, H2PO-, and SO are determined, the method further comprises: substituting the determined values of the WO:”, HWOr, H:PO-r, and SO concentrations into Formula (I) to calculate EC50 of WO4* on wheat root system; and substituting the determined values of the WO:%, HWOr, H:PO-, and SO concentrations, obtained in the step (a), into Formula (III) to calculate EC50 of HWO- on wheat root system; EC500° ! = Eppan EPO Kena BO: Mab) Formula (II) BSO; 1st 04 Ke mn WPO; + Kon oi ) Formula (IIT) in the formulas (II) and (IIT), Jie =0.24-0.36; B=1.92-2.06; logKwosgr=4.05-4. 11; logKrwo:81=6.39-6.49, logKrerossr=2.00-2.18; logKsossr=1.70-2.04; and, {WO}, {HWOr}, {HPO}, and {SO} represent the determined values of the WO”, HWOr, HoPOr, and SO4* concentrations, respectively.
    In the case of Jimai 22, for the formulas (I), (II), and (III), Sint =0.30, B=1.99, logKro4er=4.08, logKerro421=6.44, logK mara: =2.09, and logKsossr=1.87. The invention will now be described in connection with example embodiments.
    Apparently, these example embodiments are not all of but only part of the embodiments of the invention.
    All other embodiments obtained by those skilled in the art based on the embodiments described herein without creative efforts shall fall within the protection scope of the invention.
    Example 1 Bio-available forms of W(VI) which were considered to be toxic to wheat root elongation, at different pH levels or with the presence of differing coexisting ions, and effects of coexisting ions on the W(VI) toxicity were studied through culturing of soil simulation solutions.
    Effects of the pH values of the solutions and of the coexisting ions on the W(VI) toxicity to wheat root elongation and quantification of the relationships therebetween were further determined through the single factor test.
    Complexing stability constants of the various W(VI) forms and of the coexisting ions for the wheat root ligand were estimated.
    A Biotic Ligand Model (BLM) was established for predicting the toxicity of W(VI) in the soil stimulation solutions to wheat root elongation, and thus may provide solid scientific basis for formulation of environmental quality standards for tungsten contaminated soil and risk assessment therefor. The procedures in this example are shown in the flowchart in FIG. 1.
    Materials and methods
    1. Experimental materials Agents: Na2WO,, CaCly, NaCl, NaSOs, NaNO;, NaH;PO4, NaOH, HCl, 2-[N- morpholino] ethane sulfonic acid (MES), and 3-[N-morpholino] propane sulfonic acid (MOPS). As 1 mM MES (pH<7.00) and 3.6 mM MOPS (pH>7.00) are each not complexed with the tungsten metal, they do not affect the forms and toxicity of the metal and thus serve as pH stabilisers here. Experimental wheat variety: Jimai 22.
    2. Preparation of solutions Effects of each of pH, H:POr, SO4%, NOs’, and CT on toxicity of W(VI) to wheat were investigated with single factor method. So, there were five such experimental groups, i.e., groups for HPO, SOs, NOs, Cl, and pH. A series of runs were performed for each group using the corresponding solutions having differing concentrations of H2PO:, SO4*, NOs, or CI, or the solutions having different pH values to conduct interactions with solutions having differing concentrations of W(VI) in the range of 0.01 to 500 uM. The pH ranged from 6 to 8.5, and the concentration ranges of the ions corresponded to the concentrations thereof in soil pore water (as shown in Table 1). 0.2 mM CaCl; was used as the background solution of the groups other than the group for CT. Each run was repeated 3 times. The pH values were adjusted using 1 M HCI and 1 M NaOH.
    3. Wheat root elongation inhibition test Referring to the test method for wheat growth and cultivation in soil, plastic beakers, suitable for growth of wheat seedlings, and healthy and plump wheat seeds were selected. The selected seeds were sterilized using 30 % H20: for 20 min. Thereafter, they were cleaned by flushing with deionized water, and were then placed on an iron dish lined with a sterilized filter paper. Deionized water was then added to the dish such that the seeds were submerged in water. The dish was then placed into an incubator for culturing at 20 °C for 36 h without light irradiation. The seeds were transferred into the plastic beakers after radicle emergence and root growth up to 2 mm, with 7 seeds in each beaker for further culturing (14 h and (24+2) °C per day, 10 h and (18+2) °C per night, and illumination intensity: 25000 Ix). Seed culture liquid exchange was performed once every 2 days. After 5 days, root lengths were measured and relative root elongation (RE, %) of wheat subjected to the solutions having differing concentrations of W(VI) was calculated.
    4. Prediction of W(VI) forms The forms or species of W(VI) were predicted using Visual Minteq3.0 software. When the prediction was conducted, the pH and the concentrations of W(VI), K*, Ca *, Nat, PO”, SO4%, NOs", and Cl were each inputted, and the partial pressure of CO» was set to3.5x107 atm.
    5. Statistic processing of data Dose-response curves were fitted with the log-logistic equation (Formula TV), y=- Yo 1+e®x—a)h : Formula (IV) The curve fitting was performed using Microsoft Office Excel. EC50 values (EC50 is the dosage of tungsten at which 50 % of an evaluation index was inhibited as compared to control) of the various evaluation indexes and 95 % confidence intervals were derived from the fitted curves. In the formula (TV), y represents a value of an evaluation index, x represents natural logarithm of the tungsten dose, yo and b are fitted parameters, and a=login(ECS0).
    The statistical analysis of the data was carried out by the software of Statistic Package for Social Science (SPSS). Here, when the data value of the significant difference was below 0.05 (p<0.05), the least significant difference test (LSD) of one-way ANOVA analysis was used for statistics.
    6. Mathematical basis of W(VI)-BLM W(VI) was present in the solutions having a pH value of 6.0 to 8.5 in the forms of WO: and HWO:. WO” was regarded as the toxic form of W(VI) which was most likely to act on the biological ligand. According to the BLM theory, the tungsten ions were bound to biological ligand (BL) binding sites, and the coexisting anions competed with the tungsten ions for binding to the BL binding sites. According to the hypothesis of the BLM, when the competing ions including OH, H:PO:, SO4%, NOx", and Cl were taken into account, the fraction of all BL binding sites occupied by the tungsten ions was defined as f (also called partition coefficient), the magnitude of which is independent of biomass and the total number of the ligands, The partition coefficient f could be expressed as a following Equation (1):
    ho TO Krom WO} /
    FOE I+ Kyo, a wo : - | +K OHBL lon . + K Ho POLBL 7 7 ‚P O° + K SO, BL 507 i + Ko NO i+ K CIBL cr} 5 . Equation (1) When 50 % inhibition occurred, Equation (1) could be represented by a following Equation (2): fo
    - Ee J megs , ert, { 1, ep! vt oz de)
    ECSOPO: Pe KomlOH HK pon HPO Ko SO HK 5 NO + Kogge CT} . vaar WEL | Equation (2) where, EC50{WO, } represents the activity of free tungsten ions at 50 % inhibition of {9% wheat root elongation, and * *«= represents the fraction of all wheat root binding sites occupied by the tungsten ions at 50 % inhibition of wheat root elongation.
    The relative root elongation could be expressed as a following Equation (3): 100 RE =— { WOgBL i + | fom v FOL Equation (3) From Equation (1) above, Equation (3) could be transformed into a following Equation (4): 4 Ad Jard - 14 / Ko, Wo i / | ' Ln + Kyo Wor i+ Kosar OH i+ Ki rom #1, PO, + Kom New + Ki a NO, f+ Kes: cr
    Equation (4) Equation (4) was the mathematical basis of W(VI)-BLM.
    Root Mean Square error (RMSE) acquired by fitting using DPS 9.0 software
    (http://www.chinadps.net/index htm) was used as a criterion for determining optimal parameters, RMSE = = > Roese = Ropes where, N is the number of data to be processed, Rmeasurea is a measured value of relative root elongation, and Rpredieea 18 a predicated value of relative root elongation. Results and analysis
    1. Distribution of various forms of W(VI) at different pH levels Distribution of various forms of W(VI) at pH levels of 6.0 to 8.5 is as shown in FIG. 2. At pH 6, the contents of WO:%, HWO:, and CaWO:(aq) in the solutions were 82.27 %,
    0.34 %, and 5.21 %, respectively, with respect to the total amount of W(VI). As pH increased, the WO:4%, HWO:, and CaWO:(aq) contents did not vary significantly. In particular, the WO: and CaWQs(aq) contents demonstrated a slightly upward trend, while the HWO: content gradually tended towards 0.001 nM. At pH 8.5, the contents of WO, HWOr, and CaWO:(aq) were 82.85 %, 0.001 %, and 5.25 %, respectively, with respect to the total amount of W(VI). Contents of other forms, such as, W-024*"and HW-0,4>, were very low at any pH level within the above range, so they were not taken into account. Therefore, the three major forms of W(VI), i.e, WO4>, HWOy, and CaWO:(aq), would be subjected to analysis of possible toxicity to wheat root elongation at a next step.
    2. Effects of pH and coexisting anions on W(VI) toxicity Table 1 shows chemical compositions of the test solutions used in each run, and corresponding ECS0 values expressed as ECSO{W(VI)r}, ECS0{WO0.¥}, and EC50{HWO:} and 95 % confidence intervals. Table 1 Chemical compositions of test solutions in each run and EC50 values © EC50value and 95% confidence interval M EC50{HWOy }/nM 05 281(232-340) 218(182-26.1) 90.9(758-109) SO& (mM) 1 31.5(28.6-34.7) 23.2(21.2-25.4) 96.9(88.6-106)
    2.5 36.2(32.3-40.6) 24 1(21.7-26.8) 101(90.6-111)
    © EC50valueand 95% confidence interval 3 Run PE CoO: Hu ECS0{HWOs nM 429(39.0-472) 256(234-280) 107(97.6-117)
    52.3(47.3-57.8) 26.9(24.6-29.4) 112(103-122)
    63.6(58.3-69.5) 29.6(27.5-31.8) 123(115-133) 05 349630.9-39.3) 28151314) 117(105-131) 1 40.1(36.5-44.1) 31.4(28.9-34.2) 131(121-143) H:POr 2.5 45.7(40.7-51.3) 33.7(30.5-37.4) 141(127-156) (mM) 5 54.8(49.7-60.3) 37.7(34.3-41.3) 157(143-172) 10 64.9(60.6-69.6) 40.4(38.0-43.0) 168(158-179) 15 72.9(69.8-76.2) 42.2(40.6-43.8) 175(169-183) OT 258(217-307) 203(172-24.1) 848(71.7-100)
    2.5 26.6(22.2-31.8) 19.8(16.6-23.6) 82.5(69.2-98.4) NO; (mM) 5 27.4(22.7-33.1) 19.1(15.9-22.9) 79.5(66.1-95.6) 10 28.3(24.4-32.9) 17.9(15.4-20.7) 74.6(64.4-86.4) 15 32.0(29.5-34.8) 18.8(17.4-20.7) 78.5(72.5-85.0)
    39.0(34.9-43.6) 19.8(17.8-22.0) 82.5(74.1-91.8) 1 248221278) 196(175-218) 815(73.1909)
    2.5 25.7(22.2-29.8) 19.1(16.6-22.1) 79.8(69.0-92.2) Cr (mM) 5 26.1(22.2-30.8) 18.2(15.5-21.3) 75.8(64.6-89.0) 10 28.1(24.0-33.0) 17.8(15.2-20.8) 74.1(63.2-86.9) 15 29.4(24.4-35.4) 17.3(14.4-20.8) 72.1(60.0-86.5) 30 32.1(28.8-35.9) 17.3(13.8-21.7) 68.0(61.2-75.6) 60 247(218279) 205(183-23.1) 855(76.1-96.1)
    6.25 29.1(23.7 -35.6) 24.3(19.9 -29.6) 57.0(46.7-69.5)
    6.5 36.8(34.4-39.2) 30.8(28.9-32.8) 40.5(38.1-43.2)
    7.0 41.7(36.5-47.5) 34.8(30.7-39.5) 14.5(12.8-16.5) PH 7.5 43.6(40.6-46.9) 36.4(34.1-38.9) 4.82(4.50-5.10)
    7.75 44.2(42.8-45 8) 37.0(35.9-38.2) 2.71(2.70-2.80)
    8.0 45.6(42.0-49.4) 38.0(35.3-41.0) 1.68(1.50-1.70)
    8.5 46.6(43.3-50.1) 38.9(36.4-41.6) 0.51(0.47-0.58)
    It can be seen from Table 1 that, when the pH was increased from 6 to 8.5, EC50{W(VDr} and EC50{WO. } were increased from 24.7 and 20.5 uM to 46.6 and
    38.9 uM, respectively, with a 1.89-fold and a 1.90-fold increase, respectively. Unlike EC50{W(VI)r} and EC50{WOs"), when pH was increased from 6 to 8.5, EC50{HWO:'} was decreased from 85.5 to 0.51 nM, with a 167.6-fold decrease. These suggest that the W(VI) toxicity was influenced significantly by the pH possibly through transformation among the W(VI) forms and competition with OH" alone or in combination. According to the theoretical basis of the BLM, if OH’ and WO." compete with each other at a high pH level for binding to the ligand binding sites, the OH’ activity should be linearly dependent on EC50{WO4”} and thus logKorer was set to zero. It follows from W(VI) form analysis that changes in pH value affected transformation among the W(VI) forms, and changes in the contents of WO4 and HWOr with pH value can be used to explain why there was change in toxicity of W(VI). As the pH value was increased, H* activity was gradually decreased and hence the WO+ activity and EC50{WO0.*} were slightly increased; and the HWO- activity was decreased and hence EC50{HWO:} decreased sharply. FIG. 3 shows that the OH activity was not linearly dependent on EC50{WO: } or EC50{HWO:}, which suggests that OH" ions did not compete with WO or HWO- ions for binding to the binding sites on the wheat root ligand, and the toxicity of W(VI) to wheat was reduced by transformation among the W(VI) forms.
    Analysis of correlation between EC50{W0O4>"} and HWO:/WO: and CaWO4/WOs* was conducted. As shown in FIGS. 4 and 5, there was a linear relationship (R*>0.99) between 1/ECS0{WO4*} and HWO:/WO , which had a significant slope, and there was no linear relationship between 1/EC50{W0.*} and CaWO:/WO:”.
    Assuming that variation of EC50{WO+} with a change in pH was caused by transformation among the different forms of W(VI), Equation (2) could be transformed into a following Equation (5) based on equilibrium equations of WO +H*=HWO4 and WO4+Ca7=CaWO..
    1 AEN KK Wo}, {Cawo ‚} ECs0WOT] © | woar t Apo. or] Cao LBL ve Equation (5)
    Equation (5) could be transformed into a multiple regression equation, as shown in Equation (6), with 1/EC50{WO:*} as the dependent variable as well as {(HWOr} {WO} and {CaWO:}/{WO: } as the arguments (independent variables). i snes 1/7 . . gezo wor! = U me) Je | 0.552(40.067)**+2.65(20.225}5** oe _ ET] J (R2=0.99, p<0.001) Equation (6) According to Equation (5), if HWO4* and CaWOa are toxic forms of W(VI), 1/EC50{WO } should be linearly dependent on HWO:/WO: and CaWO:/WO: . From Equation (6), it can be found that, for the intercept and slope of {HWO:}/{WO4}, p<0.001; while for {CaWOa4}/{WO:7}, no significant difference was observed (p>0.05), and {CaWO:}/{WO:} could thus not be ignored. Therefore, two major contributors to the toxicity of W(VI) to wheat root elongation were WO: and HWO-. Due to site competition from H:PO:. SO4*, NO, and CI, toxicity thresholds of W{(VD) in the forms of total W(VI), WO4*, and HWOr, expressed as ECSO[W(VI)r], EC50{WO0.*}, and EC50{HWO:}, varied widely. It can be seen from Table 1 that, when the NO: activity was increased from 0.001 to 25.224 mM and the CI activity was increased from 1.34 to 25.5 mM, EC50{WO#} and EC50{HWO:} were not significantly affected. As can be appreciated from Table 1 and FIGS. 6 to 9, when the activity of HsPO: and HPO.” (since the proportion of H2PO: was 90 % or more, “HPO” is used to represent the sum of H;PO and HPO” hereinafter) was increased from 0.445 to 11.6 mM, EC50{WO+*3 and EC50{HWO:} increased linearly from 21.8 and 90.9 mM to 29.6 and 123 mM, respectively; and when the SO: activity was increased from 0.396 to 6.49 mM, EC50{WO 3} and EC50{HWO:} also increased linearly, from 28.1 and 117 mM to 42.2 and 175 mM, respectively, with a 1.5-fold and a 1.49-fold increase, respectively. From the above results, it is found that H2PO- and SO: competed with WO and HWO- for binding to wheat root binding sites, while NOs" and Cl did not compete with them. So, logKxvosz, and logK os, were each set to zero.
    3. Optimization of Biotic Ligand Model (BLM)
    When the toxicity of WO4> and HWO: was taken into account, Equation (1) was transformed into a following Equation (7): 7 Koa WO, > } + Kros: IH WO: } C+ Koon Wor j+ K HWCLBL H WOS } + Ky roer i 1,POs + Kom is Of j Equation (7) The above Formula for calculating the relative root elongation was modified into a following Equation (8): RE= — 100 ~ al Korn WOS + Kro a AHO ui sens) - rey 2 ( TLT ( “1. U =| Lf GEL I+ Room WO, i+ K woe HH WO: 1+ Ko pom 1 POs + K 50 150: } J Equation (8) In order to confirm this optimized result, FIAM (Equation (9) and Equation (10)) was introduced here to make a comparison with the BLM. Comparison results are shown in Table 2. It was further found that, as compared with FIAM, the BLM had an improved capability of predicting the toxicity of a metal to plants. RE = — | ECso{muol | Equation (9) | {HO | | EC50, HWuO, 5) Equation (10) Table 2 Fitted parameters by FIAM and BLM LogK EC50{W0:*}/{H RM 3 Model Rr WOr} (M) or 8 WO HWOs HPO: SO: SE pe wos OLLI , 6.34 25.13+1.10 FIA = 7 06 M HW 0.7 191 0.75+40.
    0.06+0.10 Of 1 8 11
    40840 64440 209+0 187+0 0.9 1.99+0. BLM 471 0.30+0.06 .03 05 ‚09 17 8 07 Wheat root elongation was influenced by {WO}, {HWOr}, {H:POs}, and { SO}. Since {OH}, {NOs}, and {CI} had no effect on the toxicity of W(VI), they were excluded from Equation (7) described above. Parameters obtained through Mathematical Model function of DPS 9.0 software, such as, logKrosi=4.08, logKuwoms=6.44, logKuzromi=2.09, logKsoi.n=1.87, fint =0.30, and 5=1.99, further indicate that, as compared with FIAM, the BLM had an improved capability of predicting the toxicity of a metal to plants.
    4. Validation of W(VI)-BLM To verity the accuracy of the BLM parameters obtained, a back-substitution method was employed to determine an agreement between predicted and measured EC50{WO 3 and EC50{HWO:}. On the basis of Equation (8), EC50{WO4*} and EC50{HWO:} could be respectively expressed as follows: Cy BOR LPO, JK 4507) ECsopo; je ———— 2 k Wo, } J Equation (11) oy BEE pgo VLPOT + Kg SOE) EC50HWO, {= Lo —r i : AHWO, | Equation (12) Values of Kwoupr, Kuwoas,, Krossr, Ksospr, and J vir as shown in Table 2 were substituted into Equations (11) and (12). Then, values of EC50{WO:#} and of EC50{HWOr} could be obtained from {WO}, {HWO4}, {HPO:}, and {SO4 }. As can be appreciated from FIGS. 10 and 11, predicted values of EC50{WO4*} and ECS0{HWOy } were within 2 times the measured values thereof. It can be seen from Table 2 and FIGS. 12 to 17 that, when the toxicity of W(VI) to wheat root elongation was predicted by using FIAM-WO4 and FIAM-HWOy", the RMSE value was 6.34 and 19.2, respectively, and R was 0.97 and 0.71, respectively. In contrast, the BLM took into account competition between the various forms of W(VI) and the coexisting anions, and thus had an improved capability of predicting the toxicity
    . : . 21 fo of W(VI) to wheat root elongation, with RMSE being 4.71, R* being 0.98, and ” #2: consistent with inhibition of wheat root elongation. The BLM explains the relationship between the wheat root ligand and the various forms of W(VI), and is believed to be a good model predictive of ecological risk. Relationships between the values of EC50{WO+} and EC50{HWO:} and the H2PO: and SO” activities, as shown in Equations (11) and (12) and FIGS. 6 to 9, suggest that HPO and SO4 competed with the toxic forms of W(VI) for binding to the wheat root ligand. Equation (8) and FIG. 15 further strengthen our conclusion that WO: and HWO: were toxic forms of W(VI) and H;PO: and SO competed with them for binding to the wheat root ligand.
    The invention is described above based on preferable embodiments. It will be apparent to those skilled in the art that various improvements and embellishments can be made without departing from the concept of the invention, and should fall within the scope of the invention as defined by the appended claims.
    权利要求:
    Claims (3)
    [1]
    A method for predicting W(IV) toxicity in wheat root elongation, the method comprising the steps of: a. determining concentrations of WO: , HWOr, H:PO- and SO4 in a soil for growing wheat, the concentrations being expressed in the same unit; and B. substituting the determined values of the WO4 >, HWO:, HoPOr and SO: concentrations in Formula (I) to calculate relative root elongation; 00 RE = — 1 | Kyo sc WOS {+ Korg {HO} | { Fer {i + Kone ¥ VO" } + & gga WI WOT } + Kg roa it LPO (3 Ky ge Sr ) J Formula (I) .. : fi where, RE represents the relative root extension, “#3: = 0 .24 - 0.36; B = 1.92 — 2.06; logKwoasL = 4.05 — 4.11; logKawosr = 6.39 — 6.49; logKuzpousr = 2.00 — 2.18; logKsoaeL = 1.70 — 2.04; and, {WO}, {(HWO:}, {H2PO:} and {SO47} represent the determined values of the WO:-, HWO:-, HoPOr and SO4 concentrations, respectively.
    [2]
    The method of claim 1, wherein step (b) further comprises substituting the determined values of the WO:", HWO:, H:PO: and SO4: concentrations obtained in the step (a), in Formula (II) to calculate EC50 of WO: in wheat root system, and substituting the determined values of the WO:47-, HWO:-, H:PO:- and SO1,* concentrations obtained in step (a), in Formula (IIT) to calculate EC50 of HWO- in wheat root system; sg pe i lp feos ef Yom 3+ K HB VL PO, Kot WU, ) ECS0yVO, i= TT TTT me i pe - WER ij] { = we | Kowa + Ko, Wor) } : i Formula (II)
    _18- NR ey oe { ie i ro {, wrs È ee rene Ja: FE a GPO, i + Km SOT pan) pe Wor {1 - / BE ] K HELL BE + Kn a Teron SY |
    I SENEWO Formula (IIT) wherein, in the formulas (II) and (III), Joa = 0.30; logKwousr = 4.08; logKnawousr = 6.44; logKinpossr = 2.09; logKsoaer = 1.87; and, {WO}, {HWO:}, {H2POs} and {SO} represent the determined values of the WO:, HWOy, HoPOr and SO:# concentrations, respectively.
    [3]
    The method of claim 1 or 2, wherein the wheat variety comprises Jimai 22, Jimai 23, Jimai 44 and Yanmai 1212.
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    同族专利:
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    NL2027968B1|2021-10-14|
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    CN106916213B|2015-12-25|2020-04-21|中国农业大学|Protein AsT, coding gene thereof and application thereof in plant stress tolerance|
    CN106932538A|2017-03-29|2017-07-07|南京大学|A kind of nickel ion is to the Forecasting Methodology of wheat root elongation toxicity and its application in soil|
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