A method for safe utilization applicable to slightly and moderately cadmium-polluted calcareous soils

Abstract

The present invention relates to the technical field of safe utilization of contaminated cultivated land, and particularly relates to a safe utilization method applicable to slightly and moderately cadmium-contaminated calcareous soil. The present invention provides a safe utilization method applicable to slightly and moderately cadmium-contaminated calcareous soil. Wheat is planted on the cadmium-contaminated calcareous soil, and the grains of the harvested wheat are used as seeds after maturity; in the next wheat growing season, the seeds are planted in uncontaminated clean soil, and wheat grains meeting the national food safety standards are harvested after maturity. This method can not only ensure the safe utilization of cadmium-contaminated cultivated land, no secondary pollution of clean soil, and the green and safe production of wheat, but also has low cost, convenient operation, and is easy to promote, achieving a win-win situation of economic, ecological, and social benefits.

Description

Technical Field

[0001] The present invention relates to the technical field of safe application of contaminated cultivated land, and particularly relates to a safe utilization method applicable to slightly and moderately cadmium-contaminated calcareous soil. Background Art

[0002] At present, in slightly and moderately cadmium-contaminated areas, the safe utilization of contaminated cultivated land is advocated, and agronomic measures are mostly adopted to control the cadmium accumulation in the edible parts of wheat, and finally reduce the cadmium content in wheat grains. For example, CN116921407A, CN116369321A, CN116463245A and CN115589912A, but the cadmium content in wheat grains is still difficult to be reduced below the national food safety standard limit of 0.1 mg / kg (GB 2762-2022). Moreover, some agronomic measures are complex in operation, high in cost, unstable in subsequent control effects and sometimes cause secondary pollution, resulting in the cadmium content of wheat grown on cadmium-contaminated cultivated land exceeding the standard and being difficult to be safely consumed. It cannot be normally circulated as food commodities and can only be treated as feed or raw materials for brewing. Not only is it difficult to make full use of the cadmium-contaminated soil, resulting in a waste of cultivated land resources, but also the economic benefits are reduced and the income of farmers is affected. Summary of the Invention

[0003] In view of this, the present invention provides a safe utilization method applicable to slightly and moderately cadmium-contaminated calcareous soil. This method can not only ensure the safe utilization of cultivated land soil in cadmium-contaminated areas and the clean and safe production of wheat, but also has low cost, is easy to operate, and is easy to realize large-scale popularization and application, achieving a win-win situation of economic, ecological and social benefits.

[0004] To solve the above technical problems, the present invention provides a safe utilization method applicable to slightly and moderately cadmium-contaminated calcareous soil. Wheat is planted in slightly and moderately cadmium-contaminated calcareous soil. After maturity, the grains of the wheat are harvested as seeds. In the next wheat growing season, the seeds are planted in uncontaminated clean soil. After maturity, wheat grains meeting the national food safety standard are harvested.

[0005] The inventors found in multiple planting experiments that the cadmium content in the grains obtained after planting wheat in cadmium-contaminated calcareous soil is often higher than the requirements for cadmium content in the national food safety standard. However, when the grains with excessive cadmium content are used as seeds and planted in uncontaminated clean soil in the next season, the cadmium content in the obtained grains is much lower than the safety limit requirements for cadmium content in the national food safety standard. Moreover, considering that the seeds of grains with excessive cadmium content may cause cadmium pollution to uncontaminated clean soil, after the crops are mature and harvested, the cadmium content analysis of the rhizosphere soil of the crops is continued. The results show that the physical and chemical properties of the uncontaminated clean soil, especially the total cadmium content and available cadmium content, are not affected by the seeds of crops with excessive cadmium content.

[0006] The present invention uses calcareous soil contaminated by light to moderate cadmium as a wheat seed production base. Wheat is planted in the cadmium-contaminated calcareous soil and the grains are harvested. Regardless of the cadmium content in the grains, they can be used as seeds, and the germination rate of the seeds is comparable to that of normal clean seeds. In the next sowing season, the harvested seeds are planted in uncontaminated clean soil, the grains are harvested after maturity, and the cadmium content in the grains is measured, so that crop grains meeting the national food safety standards can be obtained.

[0007] Combined with the first aspect, the cadmium content in the calcareous soil contaminated by light to moderate cadmium ranges from 1.2 to 3.0 mg / kg. According to the "National Soil Pollution Status Survey Bulletin" published by the Ministry of Environmental Protection and the Ministry of Land and Resources in 2014, when the pollutant content exceeds 2 to 3 times (inclusive) of the evaluation standard, it is lightly polluted; when the pollutant content exceeds 3 to 5 times (inclusive) of the evaluation standard, it is moderately polluted.

[0008] Preferably, the cadmium content in the calcareous soil contaminated by light to moderate cadmium ranges from 1.5 to 2.5 mg / kg.

[0009] More preferably, the cadmium content in the calcareous soil contaminated by light to moderate cadmium is 1.8 mg / kg.

[0010] The calcareous soil in the present invention contains calcium carbonate and / or magnesium carbonate, which are mainly in the free state. This calcareous soil is widely distributed in North China, Northeast China and Northwest China, and has the water conditions of semi-humid and semi-arid, arid soils.

[0011] Combined with the first aspect, the pH value of the calcareous soil is 7.5 to 8.5.

[0012] Preferably, the pH value of the calcareous soil is 7.8 to 8.2.

[0013] Preferably, the wheat variety can be Jimai 22 or Yannong 1212, or other wheat varieties with low cadmium accumulation.

[0014] Combined with the first aspect, the wheat straw planted in the calcareous soil contaminated by light to moderate cadmium or planted in uncontaminated clean soil is harmlessly treated.

[0015] The beneficial effects of the present invention are as follows: The safe utilization method applicable to cadmium-polluted calcareous soil provided by the present invention uses the cadmium-polluted calcareous soil as a wheat seed multiplication base, realizing the safe application of polluted cultivated land. At the same time, when the crop seeds obtained from this seed multiplication base are sown in unpolluted clean soil the following year, their germination rate is equivalent to that of clean seeds, and the cadmium content in the harvested seeds meets the national food safety standard (0.1 mg / kg). In addition, the method of growing wheat seeds with excessive cadmium in unpolluted clean soil adopted in the present invention will neither have an adverse effect on other elements in the harvested wheat seeds nor cause adverse effects on the unpolluted clean soil, realizing the safe application of polluted cultivated land and ensuring the safe production of wheat. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a control chart of the influence of clean wheat seeds and wheat seeds with excessive cadmium of two varieties on the wheat germination rate in the embodiment of the present invention;

[0017] Figure 2 It is a control chart of the cadmium content in each part of wheat seedlings after 7 days of germination of clean wheat seeds and wheat seeds with excessive cadmium of Jimai 22 in the embodiment of the present invention;

[0018] Figure 3 It is a control chart of the cadmium content in each part of wheat seedlings after 7 days of germination of clean wheat seeds and wheat seeds with excessive cadmium of Yannong 1212 in the embodiment of the present invention;

[0019] Figure 4 It is a control chart of the cadmium content in the mature seeds corresponding to clean wheat seeds and wheat seeds with excessive cadmium of two varieties grown and matured in culture boxes in the embodiment of the present invention;

[0020] Figure 5 It is a control chart of the cadmium content in the mature seeds corresponding to clean wheat seeds and wheat seeds with excessive cadmium of two varieties grown and matured in experimental fields in the embodiment of the present invention;

[0021] Figure 6 It is a control chart of the content of each element in the wheat seeds harvested from clean wheat seeds and wheat seeds with excessive cadmium of Jimai 22 in the embodiment of the present invention;

[0022] Figure 7 It is a control chart of the content of each element in the wheat seeds harvested from clean wheat seeds and wheat seeds with excessive cadmium of Yannong 1212 in the embodiment of the present invention;

[0023] Figure 8 It is a control chart of the cadmium content in the rhizosphere soil corresponding to clean wheat seeds and wheat seeds with excessive cadmium of two varieties grown and matured in experimental fields in the embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0024] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the following further elaborates on the present invention in combination with specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0025] Given that the current cost of remediating cadmium-contaminated soil is relatively high, the remediation efficiency is low, and the remediation cycle is long, and the method of reducing cadmium content by controlling cadmium accumulation in the edible parts of grains has the defects of complex agronomic measures, high costs, and unstable subsequent remediation effects, resulting in the difficult safe utilization of cadmium-contaminated soil and wasting land resources. The present invention provides a safe utilization method applicable to slightly and moderately cadmium-contaminated calcareous soil, which can not only achieve the safe utilization of cadmium-contaminated soil, but also ensure the safe production of wheat. At the same time, this method is easy to promote and apply on a large scale, and can promote the win-win situation of economic, ecological and social benefits.

[0026] The following further elaborates on the present invention through specific embodiments.

[0027] The following further elaborates on the present invention through specific embodiments.

[0028] Embodiment

[0029] This embodiment provides a safe utilization method applicable to slightly and moderately cadmium-contaminated calcareous soil:

[0030] (1) Test materials

[0031] Clean wheat seeds (L): Jimai 22 (denoted as L-Jimai 22) and Yannong 1212 (denoted as L-Yannong 1212); cadmium-exceeding wheat seeds (H): Jimai 22 (denoted as H-Jimai 22) and Yannong 1212 (denoted as H-Yannong 1212). The cadmium contents of different wheat seeds are shown in Table 1.

[0032] Table 1

[0033]

[0034] Among them, the clean wheat seed Jimai 22 was purchased from Hebei Letu Seed Industry Co., Ltd., and Yannong 1212 was provided by the Agriculture and Rural Affairs Bureau of Caofeidian; the cadmium-exceeding wheat seeds Jimai 22 and Yannong 1212 were obtained from the wheat grains after planting the corresponding clean wheat seeds in cadmium-contaminated calcareous soil (pH = 8.08, cadmium content = 1.80 mg / kg, located in Xilaladi Village, Anxin County, Xiongan New Area, Hebei Province) and through conventional field management; the field application location of the clean soil was the teaching experimental field of Hebei Agricultural University in Baoding, Hebei Province. The basic physical and chemical properties of the experimental field soil are shown in Table 2.

[0035] Table 2 Basic physical and chemical properties of the experimental field soil

[0036]

[0037] As can be seen from Table 2, the total cadmium content of the experimental field used in this example is 0.25 mg / kg, which is lower than the threshold standard of 0.36 mg / kg for cadmium content specified in the national standard GB / T 41685-2022 (Thresholds of Cadmium, Lead, Chromium, Mercury, and Arsenic in Soils for Safe Wheat Production), and it is determined as clean soil.

[0038] (2) Experimental scheme

[0039] (2.1) Select the above-mentioned 4 kinds of wheat seeds with plump grains and consistent sizes, soak and disinfect them with 10% H2O2 for 15 min, then rinse them thoroughly with ultrapure water (rinsing more than 3 times), and soak them with an appropriate amount of ultrapure water for 12 h to break dormancy. After the wheat seeds are fully swollen, place the seeds with the ventral groove facing down in a petri dish lined with gauze. Place 30 seeds of the same kind of wheat evenly in each petri dish, set 3 replicates (i.e., 3 petri dishes) for each kind of wheat seed, and place them in a light incubator at 22°C with a light-dark ratio of 12 h / 12 h for continuous cultivation for 7 d, and keep the gauze moist during the germination period.

[0040] (2.2) Select the above-mentioned 4 kinds of wheat seeds with plump grains and consistent sizes, soak and disinfect them with 10% H2O2 for 15 min, then rinse them thoroughly with ultrapure water (rinsing more than 3 times), and soak them with an appropriate amount of ultrapure water for 12 h to break dormancy. After the wheat seeds are fully swollen, place the seeds evenly on a seedling tray for 4 - 5 d of seedling raising. Select wheat seedlings with consistent growth, cultivate them in 1 / 2 Hoagland nutrient solution until the three-leaf stage, and then transfer the wheat at the three-leaf stage to a hydroponic box filled with modified 1 / 2 Hoagland nutrient solution, and place it in an artificial climate chamber for indoor cultivation. Set the temperature at 25 / 20°C (day / night), the light cycle at 16 / 8 h (day / night) (light intensity 5000 - 6000 Lux), and cultivate until maturity.

[0041] (2.3) Plant the above-mentioned 4 kinds of wheat seeds in the above-mentioned experimental field according to the sowing habits of local farmers, and carry out field management according to local habits during the growth period of wheat. After the wheat is mature, according to the three-point sampling method for each quadrat, collect 5 whole wheat plants at each sampling point, collect wheat grains separately, and collect rhizosphere soil by the "shaking root method", place it in an air-drying box to air-dry naturally, and sieve it through a 0.15 mm sieve for storage and standby.

[0042] Test Example 1

[0043] For the test results and analysis of experiment (2.1):

[0044] After 7 d of wheat germination, calculate the germination rates of the above-mentioned 4 kinds of wheat seeds respectively. The results are as Figure 1As shown, it can be seen that for Jimai 22, the germination rates of L-Jimai 22 and H-Jimai 22 are 94.44% and 92.22% respectively; for Yannong 1212, the germination rates of L-Yannong 1212 and H-Yannong 1212 are 72.22% and 60.00% respectively. It is calculated that there is no significant effect on the germination rates of the clean wheat seeds and cadmium-exceeding-standard wheat seeds of Jimai 22 and Yannong 1212 ( P >0.05), indicating that there is no significant difference in the germination rates between the clean wheat seeds and the cadmium-exceeding-standard wheat seeds, that is, using wheat seeds with cadmium content exceeding the standard has no obvious effect on the germination rate of the seeds.

[0045] To further study the effect of cadmium content exceeding the standard in wheat seeds on the seedlings, the inventors continued to measure the cadmium content in the roots, above-ground parts (i.e., the parts other than the seeds and roots) and seed coats of the seedlings after 7 days of germination, and the test results are respectively as Figures 2 - 3 shown.

[0046] From Figure 2 it can be seen that for the clean wheat seeds and cadmium-exceeding-standard wheat seeds of Jimai 22, the cadmium content in the corresponding seedling roots is 0.0395 mg / kg and 0.1962 mg / kg respectively, the cadmium content in the above-ground parts is 0.0212 mg / kg and 0.1682 mg / kg respectively, and the cadmium content in the seed coats is 0.0129 mg / kg and 0.1207 mg / kg respectively. It can be seen that the cadmium content in each part of the seedlings of the cadmium-exceeding-standard wheat seeds corresponding to Jimai 22 is significantly higher than that in each part of the seedlings of the clean wheat seeds ( P <0.05).

[0047] From Figure 3 it can be seen that for the clean wheat seeds and cadmium-exceeding-standard wheat seeds of Yannong 1212, the cadmium content in the corresponding seedling roots is 0.2247 mg / kg and 0.2928 mg / kg respectively, the cadmium content in the above-ground parts is 0.1606 mg / kg and 0.1624 mg / kg respectively, and the cadmium content in the seed coats is 0.0814 mg / kg and 0.1199 mg / kg respectively. It can be seen that the cadmium content in the seed coats of the seedlings of the cadmium-exceeding-standard wheat seeds of Yannong 1212 is significantly higher than that in the seed coats of the seedlings of the clean wheat seeds, showing a significant difference ( P <0.05), and although the same trend is also shown in its roots and above-ground parts, the difference is not significant ( P >0.05).

[0048] Overall Figures 2 - 3 it can be known that when planting cadmium-exceeding-standard wheat seeds, the cadmium content in each part of the wheat seedlings will increase compared with that in each part of the seedlings of the clean wheat seeds.

[0049] Test Example 2

[0050] Test results and analysis for test (2.2):

[0051] To confirm whether planting wheat seeds with excessive cadmium content will cause cadmium pollution to the mature wheat grains, the inventors measured the cadmium content of the wheat grains obtained after growing and maturing in the hydroponic boxes respectively. The results are as Figure 4 shown. It can be seen that for the clean wheat seeds and the wheat seeds with excessive cadmium content of Jimai 22, the cadmium content in their grains is 0.0058 mg / kg and 0.0068 mg / kg respectively, both far lower than the limit requirement of 0.1 mg / kg in the national standard (GB2762-2022). Moreover, compared with the clean wheat seeds, the cadmium content in the grains obtained from the wheat seeds with excessive cadmium content increased by 17.24%, but the difference was not significant ( P >0.05), indicating that the higher the cadmium content of the wheat seeds used during sowing, the higher the cadmium content in the wheat grains harvested at maturity. For the clean wheat seeds and the wheat seeds with excessive cadmium content of Yannong 1212, the cadmium content in their grains is 0.0075 mg / kg and 0.0063 mg / kg respectively, also far lower than the limit requirement of 0.1 mg / kg in the national standard (GB2762-2022). Moreover, compared with the wheat seeds with excessive cadmium content, the cadmium content in the grains obtained from the clean wheat seeds increased by 16.00%, and the difference was significant ( P <0.05) (Regarding the slightly higher cadmium content in the grains of the clean wheat seeds of Yannong 1212 than that of the grains obtained from the wheat seeds with excessive cadmium content, the inventors speculated that it might be due to the uneven distribution of cadmium content in the seeds, but both are lower than the national standard limit).

[0052] Comparing the cadmium content in the grains harvested from the clean wheat seeds and the wheat seeds with excessive cadmium content of Jimai 22 and Yannong 1212 respectively with the cadmium content in the grains before sowing (as shown in Table 3), it can be seen that after one season of growth, the cadmium content in the grains harvested at maturity decreased significantly ( P <0.05). Among them, the cadmium content in the grains harvested from the clean wheat seeds and the wheat seeds with excessive cadmium content of Jimai 22 decreased significantly by 42.00% and 94.77% respectively, and the cadmium content in the grains harvested from the clean wheat seeds and the wheat seeds with excessive cadmium content of Yannong 1212 decreased significantly by 90.63% and 94.75% respectively. From this, it can be shown that the higher the initial cadmium content in the wheat seeds used before sowing, the greater the decrease in the cadmium content in the wheat grains harvested after one season of growth, and the stronger the dilution effect.

[0053] Table 3

[0054]

[0055] To further verify the reliability of the above-mentioned safe utilization method provided by the present invention, the wheat grains sown and harvested in the above experimental field according to this method were washed with tap water, distilled water, and ultrapure water respectively, blanched at 85 °C for 30 min, and dried to a constant weight at 60 °C, and the cadmium content and the contents of other trace elements and macro elements in the wheat grains were analyzed and determined. The results are as Figures 5 - 7 shown (the data are shown in Table 4).

[0056] As can be seen from Figure 5 (Table 4), when the clean wheat seeds of Jimai 22 and Yannong 1212 and the cadmium-exceeding wheat seeds were planted in the clean calcareous soil (the physical and chemical properties are shown in Table 2), compared with the cadmium content in the wheat seeds used for sowing, the cadmium content in the wheat grains harvested from the cadmium-exceeding wheat seeds of Jimai 22 was significantly reduced by 82.69% ( P <0.05), and the cadmium content in the wheat grains harvested from the cadmium-exceeding wheat seeds of Yannong 1212 was significantly reduced by 85.75% ( P <0.05), and the cadmium contents were far lower than the limit requirement of 0.1 mg / kg in the national standard (GB2762-2022).

[0057] As can be seen from Figure 6 (Table 4), when the clean wheat seeds of Jimai 22 and Yannong 1212 and the cadmium-exceeding wheat seeds were planted in the clean calcareous soil: there were no significant differences in the contents of K, Ca, Na, Mg, S, Mn, Cu, and Zn elements in the grains harvested from the clean wheat seeds and the cadmium-exceeding wheat seeds of Jimai 22. Compared with the grains harvested from the clean wheat seeds, the P content in the grains harvested from the cadmium-exceeding wheat seeds was significantly higher by 8.55%, and the Fe content was significantly higher by 2.46%, but the differences were all less than 10%. For Yannong 1212 ( Figure 7 ), there were no significant differences in the contents of Ca, Na, Cu, and Zn elements in the grains harvested from the clean wheat seeds and the cadmium-exceeding wheat seeds, and compared with the grains harvested from the clean wheat seeds, the K content in the grains harvested from the cadmium-exceeding wheat seeds was significantly higher by 8.96%, the Mg content was significantly higher by 10.11%, the P content was significantly higher by 6.21%, the S content was significantly higher by 13.35%, the Fe content was significantly higher by 21.21%, and the Mn content was significantly higher by 5.38%, but the differences were small, and planting the cadmium-exceeding wheat seeds promoted the increase in the Fe and S contents in the wheat grains. This shows that planting cadmium-exceeding wheat seeds will not have an adverse effect on other elements in the harvested wheat grains.

[0058] Regarding the increase in the cadmium content in the wheat grains of the L-Jimai 22 variety, the inventor speculated that it might be because the cadmium content in the L-Jimai 22 seeds was too low, and there was a certain amount of cadmium in the soil, so the cadmium content in the harvested grains increased.

[0059] Table 4

[0060]

[0061] Test Example 3

[0062] Determination results and analysis of the rhizosphere soil of wheat grains obtained from Experiment (2.3):

[0063] To verify that sowing wheat seeds with excessive cadmium content will not pollute clean soil, the cadmium content in the rhizosphere soil after wheat maturation was also analyzed and measured. The results are as Figure 8 shown (the data is shown in Table 5).

[0064] Table 5

[0065]

[0066] From Figure 8 (Table 5), it can be seen that when the wheat seeds with excessive cadmium content harvested from the cadmium - polluted calcareous soil above were planted in the above - mentioned clean calcareous soil, at the time of wheat maturation, the cadmium contents in the rhizosphere soils of the clean wheat seeds and the wheat seeds with excessive cadmium content of Jimai 22 and Yannong 1212 are respectively as shown in Table 5. Although the cadmium contents in the rhizosphere soils of the clean wheat seeds and the wheat seeds with excessive cadmium content are different, there are no significant differences ( P >0.05), indicating that when the wheat seeds with excessive cadmium content are planted in clean soil, the cadmium content in the wheat seeds with excessive cadmium content will not cause adverse effects on the clean soil.

[0067] From the above examples and test examples, it can be known that the germination rate of wheat seeds with excessive cadmium content is not affected by the cadmium content. And when the wheat seeds with excessive cadmium content harvested from the cadmium - polluted calcareous soil are planted in uncontaminated clean soil, the cadmium content in the harvested wheat grains can meet the national standard limit of 0.1 mg / kg. Also, planting wheat seeds with excessive cadmium content will not cause adverse effects on other elements in the harvested wheat grains, nor will it cause adverse effects on the ecological environment of the clean soil. The above - mentioned safe utilization method for lightly and moderately cadmium - polluted calcareous soil provided by the present invention not only realizes the safe utilization of polluted cultivated land but also ensures the safety of wheat agricultural products.

[0068] The above - mentioned is only the preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, makes equivalent replacements or changes, and all should be covered within the protection scope of the present invention.

Claims

1. A safe utilization method applicable to slightly and moderately cadmium - polluted calcareous soil, characterized in that, Plant wheat in calcareous soil contaminated by light to moderate cadmium. After maturity, harvest the grains of the wheat as seeds. In the next wheat growing season, plant the seeds in uncontaminated clean soil. After maturity, harvest wheat grains that meet the national food safety standards. Among them, the variety of the wheat is a low cadmium-accumulating wheat variety. The cadmium content in the calcareous soil contaminated by light to moderate cadmium ranges from 1.2 to 3.0 mg / kg; the pH value of the calcareous soil is 7.5 to 8.

5.

2. The safe utilization method for slightly and moderately cadmium-polluted calcareous soils as described in claim 1, characterized in that, The cadmium content in the calcareous soil contaminated by light to moderate cadmium ranges from 1.5 to 2.5 mg / kg.

3. The safe utilization method for slightly and moderately cadmium-polluted calcareous soil as described in claim 2, characterized in that The cadmium content in the calcareous soil contaminated by light to moderate cadmium is 1.8 mg / kg.

4. The safe utilization method applicable to slightly and moderately cadmium-polluted calcareous soil as described in claim 1, characterized in that, The pH value of the calcareous soil is 7.8 to 8.

2.

5. The safe utilization method applicable to slightly and moderately cadmium-polluted calcareous soil as described in claim 1, characterized in that The variety of the wheat is Jimai 22 or Yannong 1212.

6. The safe utilization method applicable to slightly and moderately cadmium-polluted calcareous soil according to claim 1, wherein The wheat straw planted in calcareous soil contaminated by light to moderate cadmium or planted in uncontaminated clean soil is harmlessly treated.

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