CN108485671B - Cadmium-polluted soil conditioner, preparation method thereof and cadmium-polluted soil conditioning method - Google Patents
Cadmium-polluted soil conditioner, preparation method thereof and cadmium-polluted soil conditioning method Download PDFInfo
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Abstract
The invention relates to a cadmium-polluted soil conditioner, a preparation method thereof and a cadmium-polluted soil conditioning method. The cadmium-polluted soil conditioner comprises the following raw materials in percentage by weight: 1-7% of polyaluminium chloride, 3-28% of ferric sulfate, 7-28% of calcium hydrophosphate, 35-85% of citric acid, 2-15% of polyacrylamide and 0.5-8% of L-proline. The invention also discloses a preparation method of the cadmium-polluted soil conditioner and a cadmium-polluted soil conditioning method. According to the cadmium-polluted soil conditioner, the preparation method thereof and the cadmium-polluted soil conditioning method, the prepared conditioner has the characteristics of surface adsorption, surface complexation and the like, can obviously reduce the migration and effectiveness of cadmium in heavy metal-polluted soil, reduce the absorption of plants to cadmium, improve the physiological stress resistance of crops, improve the structure and the property of soil, improve the uniformity of soil microorganisms, and is particularly suitable for calcareous soil. The modifier has the advantages of easily obtained raw materials, low cost, simple preparation, simple improvement method of the cadmium-polluted soil and stable effect.
Description
Technical Field
The invention belongs to the technical field of soil remediation, and particularly relates to a cadmium-polluted soil conditioner, a preparation method thereof and a cadmium-polluted soil conditioning method.
Background
In recent years, the heavy metal pollution in China presents an aggravating situation, and the heavy metal pollution in soil poses serious threats to the ecological environment, food safety and human health. Cadmium (Cd) has nondegradable property on environmental pollution and long duration, and is difficult to reduce naturally from the environment. About 2.0X 10 in China7hm2The cultivated land is polluted by heavy metal, wherein the farmland area polluted by cadmium reaches 2.8 multiplied by 105hm2。
Common repair methods include engineering physical techniques, chemical passivation techniques, and biological repair techniques. The physical remediation technology is only suitable for remediation of small-area severely polluted soil, the bioremediation target biomass is low, the remediation period is long, and the subsequent treatment of plants is difficult, while the chemical passivation technology is a method for directly or indirectly changing the form and the biological effectiveness of heavy metals by adding a chemical modifier to change the chemical properties of the soil so as to inhibit or reduce the absorption of the heavy metals by the plants, so that the method is a low-investment and high-effect method for treating heavy metal pollution. Cadmium is mainly in an exchangeable ionic state, a carbonate combined state, an iron-manganese oxide combined state, an organic combined state and a residue state in soil, wherein the exchangeable state is an effective state which can be absorbed and utilized by plants, and the other exchangeable states are non-effective states. Moreover, the available cadmium can be converted into the non-available cadmium under certain conditions, and vice versa, namely, the available cadmium and the unavailable cadmium in the soil keep a dynamic balance. The application of the corresponding passivator in the soil can keep the effective cadmium in the soil in a low content state.
The existing chemical remediation method is widely applied to soil cadmium treatment, and the prior art has a chemical fixing agent for remediation of cadmium and lead polluted soil, the components of which comprise titanium dioxide waste residues, phosphate, oxidant and the like, and the remediation specificity on cadmium is not strong. The prior art has a passivating agent for controlling vegetable field pollution, which is mainly used for chemical remediation of south acidic soil polluted by cadmium and is not suitable for calcareous soil. The prior art has a cadmium-polluted soil conditioner which is beneficial to reducing the absorption of crops to heavy metals, and the conditioner has different effects and unstable repairing effect under different soil textures. The prior art also has a chemical repairing agent for cadmium pollution of farmland soil, which is suitable for calcareous farmland soil, and the repairing agent is applied into soil along with soil plowing and is not suitable for drip irrigation of farmlands.
The cadmium pollution of soil is treated by a chemical remediation method, but mainly acid soil in the south and less drip irrigation conditions are used, so that the cadmium pollution drip irrigation farmland soil conditioner which is non-toxic, harmless, capable of reducing the accumulation of cadmium in plants and suitable for calcareous loam, and the preparation method and the application method thereof are provided aiming at the defects of the existing chemical remediation technology.
Disclosure of Invention
The cadmium-polluted soil conditioner is non-toxic, harmless, low in cost, stable in effect, capable of reducing cadmium accumulation of plants, improving the structure and the property of soil and improving the uniformity of soil microorganisms, and is suitable for calcareous loam.
In order to realize the purpose, the adopted technical scheme is as follows:
the cadmium-polluted soil conditioner comprises the following raw materials in percentage by weight:
1-7% of polyaluminium chloride, 3-28% of ferric sulfate, 7-28% of calcium hydrophosphate, 35-85% of citric acid, 2-15% of polyacrylamide and 0.5-8% of L-proline.
Further, the content of the polyaluminium chloride is 2 to 5 percent;
the content of ferric sulfate is 7% -23%;
the content of the calcium hydrophosphate is 7 to 23 percent;
the citric acid content is 40% -75%;
the content of the polyacrylamide is 3% -11%;
the content of the L-proline is 1% -5%.
The invention also aims to provide the preparation method of the cadmium-polluted soil conditioner, which is simple, low in energy consumption and environment-friendly.
In order to realize the purpose, the adopted technical scheme is as follows:
the preparation method of the cadmium-polluted soil conditioner comprises the following steps:
(1) sequentially adding polyaluminium chloride, ferric sulfate, calcium hydrophosphate and citric acid into water, and stirring at 60-70 ℃ until the polyaluminium chloride, the ferric sulfate, the calcium hydrophosphate and the citric acid are completely dissolved to obtain a first mixture;
(2) adding polyacrylamide into the first mixture, and stirring at 67-78 ℃ until the polyacrylamide is completely dissolved to obtain a second mixture;
(3) adding L-proline into the second mixture, and uniformly stirring to obtain the cadmium-polluted soil conditioner;
the content of the polyaluminum chloride is 1-7 wt%, the content of the ferric sulfate is 3-28 wt%, the content of the calcium hydrophosphate is 7-28 wt%, the content of the citric acid is 35-85 wt%, the content of the polyacrylamide is 2-15 wt%, and the content of the L-proline is 0.5-8 wt%.
Further, in the step (1), after each component is completely dissolved, the next component is added.
Further, in the step (1), the total stirring time is 25-65 min;
in the step (2), the stirring time is 8-25 min.
Further, the volume ratio of the total mass of the polyaluminium chloride, the ferric sulfate, the calcium hydrophosphate, the citric acid, the polyacrylamide and the L-proline to the water is 25-35 g: 1L; the content of the polyaluminium chloride is 2 to 5 percent;
the content of ferric sulfate is 7% -23%;
the content of the calcium hydrophosphate is 7 to 23 percent;
the citric acid content is 40% -75%;
the content of the polyacrylamide is 3% -11%;
the content of the L-proline is 1% -5%.
Furthermore, the fineness of the ferric sulfate, the calcium hydrophosphate and the citric acid is 20-50 meshes;
the volume ratio of the total mass of the polyaluminium chloride, the ferric sulfate, the calcium hydrophosphate, the citric acid, the polyacrylamide and the L-proline to the water is 30 g: 1L of the compound.
The invention also aims to provide a method for improving the cadmium-polluted soil, which is simple and has good effect.
In order to realize the purpose, the adopted technical scheme is as follows:
the cadmium-polluted soil improvement method adopts the cadmium-polluted soil improvement agent;
adopting drip irrigation, micro-spraying and flushing modes, and applying the fertilizer into soil once or in multiple times along with water; wherein the content of the first and second substances,
the total cadmium content of the soil is less than 0.6 mg/kg-1The application amount of the modifying agent is 3kg hm-2；
The total cadmium content of the soil is 0.6-7 mg/kg-1The application amount of the modifying agent is 3-7 kg.hm-2；
The total cadmium content of the soil is more than 7 mg/kg-1The application amount of the modifying agent is 7-10 kg.hm-2。
Furthermore, the cadmium-polluted soil conditioner can be applied to soil holes at one time or irrigated along with ditches by adopting hole application and ditch irrigation.
Compared with the prior art, the invention has the beneficial effects that:
1. according to the cadmium-polluted soil conditioner, the preparation method thereof and the cadmium-polluted soil conditioning method, the soil conditioner is added with the macromolecular compound, and can be complexed or chelated with cadmium ions in soil, and meanwhile, cadmium in the soil can be fully contacted with other materials in the soil conditioner, so that the chelating ratio and effect are further improved.
2. The citric acid added in the conditioner is a high-quality complexing and chelating agent which can also complex and chelate cadmium in soil, change the form of cadmium in the soil, reduce the toxicity of the cadmium and reduce the absorption of cadmium by plants.
3. According to the cadmium-polluted soil conditioner, the preparation method thereof and the cadmium-polluted soil conditioning method, ferric sulfate and calcium hydrogen phosphate added into the conditioner can participate in soil ion exchange reaction, so that the activity of cadmium is reduced, organic and inorganic nutrients can be provided for soil and plants, the soil fertility is improved, and the soil structure is improved. The added L-proline can improve the plant resistance.
4. According to the cadmium-polluted soil conditioner, the preparation method thereof and the cadmium-polluted soil conditioning method, the prepared conditioner is a light yellow liquid, has the characteristics of surface adsorption, surface complexation and the like, can be subjected to electro-neutralization and co-precipitation with metal, can obviously reduce the mobility and effectiveness of cadmium in heavy metal-polluted soil, and is particularly suitable for calcareous soil.
5. The cadmium-polluted soil conditioner, the preparation method thereof and the cadmium-polluted soil conditioning method can change the chemical form of cadmium in soil when the conditioner is applied to the soil, the exchangeable cadmium content in the soil is reduced by 14.36-24.52%, the cadmium content in a carbonate combined state, an iron-manganese oxidation state, an organic matter combined state and a residue state is respectively increased by 52.50-62.75%, 1.80-3.69%, 9.25-19.34% and 17.03-27.56%, so that the effective cadmium in the soil is kept in a low-content state. Meanwhile, the soil can be effectively improved, wherein the cation exchange capacity of the soil is increased by 5.88-21.54%, the total nitrogen of the soil is increased by 1.18-11.51%, and the organic matter of the soil is increased by 1.40-12.03%.
6. According to the cadmium-contaminated soil conditioner, the preparation method thereof and the cadmium-contaminated soil conditioning method, the physical structure of soil is improved by applying the conditioner, the MWD value, the GMA value and the R0.25 of soil aggregates are respectively increased to 2.39-3.13mm, 3.00-4.63mm and 0.86-0.93%, and the formation of large aggregates is facilitated.
7. According to the cadmium-polluted soil conditioner, the preparation method thereof and the cadmium-polluted soil conditioning method, under the condition of alkaline cadmium-polluted soil, although the abundance of bacteria is overall high, the microbial diversity has certain difference by applying the conditioner, namely the relative proportion of common floras of a few dominant species is increased. When the repairing agent is not applied, the abundance of the actinomycete phylum is higher, and the average content reaches 19.10 percent; the modifier is applied to increase the abundance of proteobacteria, acidophyla and baromonas, and the average proportion is respectively as high as 39.89%, 19.76% and 15.30%.
8. According to the cadmium-polluted soil conditioner, the preparation method thereof and the cadmium-polluted soil conditioning method, the conditioner is combined with the characteristics of Xinjiang agriculture and is suitable for drip irrigation application; the modifier has the advantages of easily obtained raw materials, low cost, simple preparation, simple improvement method of the cadmium-polluted soil and stable effect.
Drawings
FIG. 1 is a process flow diagram of the preparation method of the cadmium-contaminated soil conditioner of the invention;
fig. 2 is a SEM image of soil in experimental test 4.
Detailed Description
In order to further illustrate the cadmium-contaminated soil conditioner, the preparation method thereof and the cadmium-contaminated soil conditioning method of the present invention, and achieve the intended purpose of the invention, the following detailed description is provided for the cadmium-contaminated soil conditioner, the preparation method thereof and the cadmium-contaminated soil conditioning method according to the present invention, with reference to the preferred embodiments. In the following description, different "one embodiment" or "an embodiment" refers to not necessarily the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.
The raw materials used in the present invention are all commercially available.
Polyaluminum chloride, also known as basic aluminum chloride, PAC, also commonly known as water-purifying agent or coagulant, is interposed between AlCl3And Al (OH)3A water-soluble inorganic high molecular polymer with a chemical general formula of [ Al2(OH)nCl6-n]m(ii) a Solid of itThe product is white, light gray, light yellow or tan grain or powder.
Ferric sulfate (Fe) with molecular formula2(SO4)3Molecular weight 399.86, the solid is an off-white powder or an orthorhombic prismatic crystalline flowing pale yellow powder.
Calcium hydrogen phosphate, white monoclinic crystalline powder, odorless and tasteless, usually in the form of dihydrate (chemical formula CaHPO)4·2H2O), stable in air, and loses crystal water to form anhydrous substance when heated to 75 ℃, and becomes pyrophosphate when heated to high temperature; is easily soluble in dilute hydrochloric acid, dilute nitric acid, and acetic acid, slightly soluble in water (100 deg.C, 0.025%), and insoluble in ethanol.
Citric acid is an important organic acid, also called citric acid, colorless crystal, often contains a molecular crystal water, is odorless, has strong sour taste and is easily dissolved in water.
Polyacrylamide (PAM) is a linear high molecular polymer, is white powder or semitransparent particles, is odorless, is soluble in water, is hardly soluble in organic solvents such as benzene, toluene, ethanol, acetone, esters and the like, and is only dissolved in about 1 percent of glycol, glycerol, formamide, lactic acid and acrylic acid; it has no corrosiveness and solid has hygroscopicity.
L-proline (proline for short) is one of eighteen amino acids of human body synthetic protein, is colorless to white crystal or crystalline powder at normal temperature, is slightly smelly and slightly sweet in taste, is easily soluble in water and ethanol, is insoluble in diethyl ether, butanol and isopropanol, and is soluble in inorganic acid.
In the invention, the polyaluminium chloride, the ferric sulfate, the calcium hydrophosphate and the citric acid are sequentially added into water to be dissolved, so that the problems of insufficient dissolution and long dissolution time caused by one-time addition are solved.
The invention has the advantages that firstly, the modifier can obviously reduce the mobility and the effectiveness of cadmium in heavy metal polluted soil, and is particularly suitable for calcareous soil. Secondly, the modifier is suitable for drip irrigation application by combining the characteristics of Xinjiang agriculture, and meanwhile, the modifier is easy to obtain raw materials, low in cost, simple to prepare, convenient to use and stable in effect. Thirdly, aiming at the reduction of the physiological stress resistance of crops caused by cadmium pollution, the components of the fertilizer can improve the effectiveness of cadmium in soil, reduce the absorption of plants to cadmium and improve the physiological stress resistance of crops. Finally, the synthesized modifier is environment-friendly, improves the structure and the property of soil and improves the uniformity of soil microorganisms.
The cadmium-contaminated soil improvement agent, the preparation method thereof and the cadmium-contaminated soil improvement method of the present invention will be further described in detail with reference to fig. 1 and 2 and specific examples:
one embodiment of the invention
Example 1.
A cadmium-polluted soil conditioner is prepared from the following raw materials: 1g (1%) of polyaluminium chloride, 7g (7%) of ferric sulfate, 10g (10%) of calcium hydrophosphate, 75g (75%) of citric acid, 2g (2%) of polyacrylamide and 5g (5%) of L-proline.
With reference to fig. 1, the specific operation steps are as follows:
(1) respectively pulverizing ferric sulfate, calcium hydrogen phosphate and citric acid into 20 mesh fine powder for use.
(2) And (2) completely dissolving the crushed fine powder and polyaluminium chloride in 4L of distilled water in sequence, carrying out high-speed homogenizing and stirring at the temperature of 67 ℃ for 30min, and adding the materials in the sequence: polyaluminum chloride → ferric sulfate → calcium hydrogen phosphate → citric acid, each component is fully dissolved, and then the next component is added to obtain a first mixture.
(3) And uniformly dissolving polyacrylamide in the first mixture, and carrying out high-speed homogenizing stirring at 73 ℃ for 10min to obtain a second mixture.
(4) And uniformly dissolving the L-proline in the second mixture, and packaging to obtain the cadmium-polluted soil conditioner.
According to the cadmium-polluted soil conditioner and the preparation method thereof and the cadmium-polluted soil conditioning method, the prepared conditioner is a light yellow liquid, has the characteristics of surface adsorption, surface complexation and the like, can be electrically neutralized and coprecipitated with metal, can remarkably reduce the mobility and effectiveness of cadmium in heavy metal-polluted soil, can reduce the absorption of plants on cadmium, and can improve the physiological stress resistance of crops; the modifier is environment-friendly, can improve the structure and the property of soil and improve the uniformity of soil microorganisms. In addition, the modifier is combined with the characteristics of Xinjiang agriculture, is suitable for drip irrigation application, and is particularly suitable for calcareous soil. The modifier has the advantages of easily available raw materials, low cost, simple preparation, convenient use and stable effect.
Example 2.
A cadmium-polluted soil conditioner is prepared from the following raw materials: 2.1g (2%) of polyaluminium chloride, 24.15g (23%) of ferric sulfate, 24.15g (23%) of calcium hydrogen phosphate, 42g (40%) of citric acid, 11.55g (11%) of polyacrylamide and 1.05g (1%) of L-proline.
With reference to fig. 1, the specific operation steps are as follows:
(1) respectively pulverizing ferric sulfate, calcium hydrogen phosphate and citric acid into 30 mesh fine powder.
(2) And (2) completely dissolving the crushed fine powder and polyaluminium chloride in 3L of distilled water in sequence, carrying out high-speed homogenizing and stirring at the temperature of 60 ℃ for 65min, and adding the materials in the sequence: polyaluminum chloride → ferric sulfate → calcium hydrogen phosphate → citric acid, each component is fully dissolved, and then the next component is added to obtain a first mixture.
(3) And uniformly dissolving polyacrylamide in the first mixture, and carrying out high-speed homogenizing stirring at 67 ℃ for 25min to obtain a second mixture.
(4) And uniformly dissolving the L-proline in the second mixture, and packaging to obtain the cadmium-polluted soil conditioner.
According to the cadmium-polluted soil conditioner and the preparation method thereof and the cadmium-polluted soil conditioning method, the prepared conditioner is a light yellow liquid, has the characteristics of surface adsorption, surface complexation and the like, can be electrically neutralized and coprecipitated with metal, can remarkably reduce the mobility and effectiveness of cadmium in heavy metal-polluted soil, can reduce the absorption of plants on cadmium, and can improve the physiological stress resistance of crops; the modifier is environment-friendly, can improve the structure and the property of soil and improve the uniformity of soil microorganisms. In addition, the modifier is combined with the characteristics of Xinjiang agriculture, is suitable for drip irrigation application, and is particularly suitable for calcareous soil. The modifier has the advantages of easily available raw materials, low cost, simple preparation, convenient use and stable effect.
Example 3.
A cadmium-polluted soil conditioner is prepared from the following raw materials: 5g (5%) of polyaluminium chloride, 3g (3%) of ferric sulfate, 28g (28%) of calcium hydrophosphate, 41g (41%) of citric acid, 15g (15%) of polyacrylamide and 8g (8%) of L-proline.
With reference to fig. 1, the specific operation steps are as follows:
(1) respectively pulverizing ferric sulfate, calcium hydrogen phosphate and citric acid into 50 mesh fine powder for use.
(2) And (2) completely dissolving the crushed fine powder and polyaluminium chloride in 3L of distilled water in sequence, carrying out high-speed homogenizing and stirring at the temperature of 70 ℃ for 25min, and adding the materials in the sequence: polyaluminum chloride → ferric sulfate → calcium hydrogen phosphate → citric acid, each component is fully dissolved, and then the next component is added to obtain a first mixture.
(3) And uniformly dissolving polyacrylamide in the first mixture, and carrying out high-speed homogenizing stirring at 78 ℃ for 8min to obtain a second mixture.
(4) And uniformly dissolving the L-proline in the second mixture, and packaging to obtain the cadmium-polluted soil conditioner.
According to the cadmium-polluted soil conditioner and the preparation method thereof and the cadmium-polluted soil conditioning method, the prepared conditioner is a light yellow liquid, has the characteristics of surface adsorption, surface complexation and the like, can be electrically neutralized and coprecipitated with metal, can remarkably reduce the mobility and effectiveness of cadmium in heavy metal-polluted soil, can reduce the absorption of plants on cadmium, and can improve the physiological stress resistance of crops; the modifier is environment-friendly, can improve the structure and the property of soil and improve the uniformity of soil microorganisms. In addition, the modifier is combined with the characteristics of Xinjiang agriculture, is suitable for drip irrigation application, and is particularly suitable for calcareous soil. The modifier has the advantages of easily available raw materials, low cost, simple preparation, convenient use and stable effect.
Example 4.
A cadmium-polluted soil conditioner is prepared from the following raw materials: 8.4g (7%) of polyaluminium chloride, 33.6g (28%) of ferric sulfate, 30g (25%) of calcium hydrogen phosphate, 42g (35%) of citric acid, 3.6g (3%) of polyacrylamide and 2.4g (2%) of L-proline.
With reference to fig. 1, the specific operation steps are as follows:
(1) respectively pulverizing ferric sulfate, calcium hydrogen phosphate and citric acid into 20-50 mesh fine powder.
(2) Dissolving the above pulverized fine powder and polyaluminium chloride in 4L distilled water, homogenizing at 68 deg.C for 45min, and adding: polyaluminum chloride → ferric sulfate → calcium hydrogen phosphate → citric acid, each component is fully dissolved, and then the next component is added to obtain a first mixture.
(3) And uniformly dissolving polyacrylamide in the first mixture, and carrying out high-speed homogenizing stirring at 72 ℃ for 12min to obtain a second mixture.
(4) And uniformly dissolving the L-proline in the second mixture, and packaging to obtain the cadmium-polluted soil conditioner.
According to the cadmium-polluted soil conditioner and the preparation method thereof and the cadmium-polluted soil conditioning method, the prepared conditioner is a light yellow liquid, has the characteristics of surface adsorption, surface complexation and the like, can be electrically neutralized and coprecipitated with metal, can remarkably reduce the mobility and effectiveness of cadmium in heavy metal-polluted soil, can reduce the absorption of plants on cadmium, and can improve the physiological stress resistance of crops; the modifier is environment-friendly, can improve the structure and the property of soil and improve the uniformity of soil microorganisms. In addition, the modifier is combined with the characteristics of Xinjiang agriculture, is suitable for drip irrigation application, and is particularly suitable for calcareous soil. The modifier has the advantages of easily available raw materials, low cost, simple preparation, convenient use and stable effect.
Example 5.
A cadmium-polluted soil conditioner is prepared from the following raw materials: 3.3g (2.2%) of polyaluminium chloride, 4.8g (3.2%) of ferric sulfate, 10.5g (7%) of calcium hydrogen phosphate, 127.5g (85%) of citric acid, 3.15g (2.1%) of polyacrylamide and 0.75g (0.5%) of L-proline.
With reference to fig. 1, the specific operation steps are as follows:
(1) respectively pulverizing ferric sulfate, calcium hydrogen phosphate and citric acid into 40 mesh fine powder.
(2) And (2) completely dissolving the crushed fine powder and polyaluminium chloride in 5L of distilled water in sequence, carrying out high-speed homogenizing and stirring at the temperature of 65 ℃ for 45min, and adding the materials in the sequence: polyaluminum chloride → ferric sulfate → calcium hydrogen phosphate → citric acid, each component is fully dissolved, and then the next component is added to obtain a first mixture.
(3) And uniformly dissolving polyacrylamide in the first mixture, and carrying out high-speed homogenizing stirring at 75 ℃ for 15min to obtain a second mixture.
(4) And uniformly dissolving the L-proline in the second mixture, and packaging to obtain the cadmium-polluted soil conditioner.
According to the cadmium-polluted soil conditioner and the preparation method thereof and the cadmium-polluted soil conditioning method, the prepared conditioner is a light yellow liquid, has the characteristics of surface adsorption, surface complexation and the like, can be electrically neutralized and coprecipitated with metal, can remarkably reduce the mobility and effectiveness of cadmium in heavy metal-polluted soil, can reduce the absorption of plants on cadmium, and can improve the physiological stress resistance of crops; the modifier is environment-friendly, can improve the structure and the property of soil and improve the uniformity of soil microorganisms. In addition, the modifier is combined with the characteristics of Xinjiang agriculture, is suitable for drip irrigation application, and is particularly suitable for calcareous soil. The modifier has the advantages of easily available raw materials, low cost, simple preparation, convenient use and stable effect.
Example 6.
The cadmium-polluted soil improvement method comprises the following steps:
the cadmium-contaminated soil conditioner of examples 1 to 5 was used. The invention is more suitable for farmland with neutral or alkaline soil, so that the application amount is different according to the total cadmium content of soil and land types of different degrees. The method comprises the following specific steps:
the total cadmium content of the soil is less than 0.6 mg/kg-1The agricultural land type is cultivated land, garden land, grassland or forest land, and the application amount of the improver is as follows: 3kg hm-2The method can adopt drip irrigation, micro-spraying and flushing application modes, can be applied once along with water or applied for multiple times, has better one-time application effect, can reduce the effective cadmium content in the soil by 7.69-58.24 percent, and can not change the type after the agricultural land is improved.
The total cadmium content of the soil is 0.6-7 mg/kg-1The agricultural land type is cultivated land, garden land, grassland or forest land, and the application amount of the improver is as follows: 3-7kg hm-2The method can adopt drip irrigation, micro-spraying and flushing application modes, can be applied along with water at one time or applied in multiple times, has better one-time application effect, can reduce the effective cadmium content in the soil by 1.75-12.50 percent, and recommends changing the land utilization type into ornamental gardens, grasslands and forest lands after the agricultural land is improved.
The total cadmium content of the soil is more than 7 mg/kg-1The agricultural land type is cultivated land, garden land, grassland or forest land, and the application amount of the improver is as follows: 7-10kg hm-2The method can adopt drip irrigation, micro-spraying and flushing application modes, can be applied once along with water or applied for multiple times, has better one-time application effect, can reduce the effective cadmium content in the soil by 1.69-71.98 percent, and recommends changing the land utilization type into forest land after the agricultural land is improved.
The modifier can also be applied to hole application and furrow irrigation, and can be applied to soil holes at one time or irrigated along with water ditches.
Two experimental tests
1. Example 1
In 2017, the field barrel-planting heavy cadmium test was carried out at the agricultural college laboratory of rock river university (N44 degrees 18 '42.37', E86 degrees 03 '20.72'), wherein the soil type was grey desert soil and the soil texture was loam. Planting crop cotton, setting 40 mg.kg in experiment-1And (4) cadmium. Applying the cadmium contaminated soil conditioner of the example 1, and applying 8.48kg hm along with the seedling emergence water by one-time drip irrigation-2. The results are as follows:
TABLE 1 cadmium content (unit: mg. kg) of various chemical forms of soil-1)
As can be seen from Table 1, after the cadmium-contaminated soil conditioner disclosed by the invention is applied, the exchangeable cadmium content in the soil is reduced by 19.36%, the carbonate binding state and the iron-manganese oxidation state are increased, the organic matter binding state is improved by 14.25%, the mobility and the effectiveness of cadmium in heavy metal-contaminated soil can be obviously reduced, and the organic matter content in the soil is improved.
TABLE 2 Cotton growth
As can be seen from Table 2, after the cadmium-contaminated soil conditioner of the present invention was applied, the plant height, leaf area, root dry weight, stem weight, leaf dry weight and boll dry weight of cotton were significantly increased, which could improve the growth of crops and increase the yield of crops.
2. Example 2
In 2017, the field barrel-planting heavy cadmium test was carried out at the agricultural college laboratory of rock river university (N44 degrees 18 '42.37', E86 degrees 03 '20.72'), wherein the soil type was grey desert soil and the soil texture was loam. Planting crop cotton, setting 40 mg.kg in experiment-1And (4) cadmium. The cadmium-contaminated soil conditioner of example 2 was applied by drip irrigation for a plurality of times during the development period, and the total amount was 9.48 kg. hm-2. In the inventive examples, the results are as follows:
TABLE 3 cadmium content of cotton (unit: mg. kg)-1)
As can be seen from Table 3, the cadmium content in the cadmium part of the crop is obviously reduced after the cadmium-contaminated soil conditioner is applied, and the absorption of cadmium by the plant can be reduced.
TABLE 4 Cotton yield composition
As can be seen from Table 4, the cadmium-contaminated soil conditioner of the present invention can increase the single-boll weight and increase the crop yield.
3. Example 3
In 2017, the field low-cadmium test was carried out at the agricultural college of rock river university (N44 degrees 18 '42.37', E86 degrees 03 '20.72'), the soil type was grey desert soil, and the soil texture was loam. Planting cotton crop, setting 5 mg.kg for experiment-1And (4) cadmium. Applying the cadmium contaminated soil conditioner of the example 3, and carrying out one-time drip irrigation with the seedling emergence water to apply 4.73kg hm-2. The results are as follows:
TABLE 5 cadmium content of cotton (unit: mg. kg)-1)
As can be seen from Table 5, after the cadmium-contaminated soil conditioner of the invention is applied, the cadmium content in the roots, stems, leaves and cotton seeds of cotton is obviously reduced, and the cadmium-contaminated soil conditioner of the invention is proved to be capable of effectively reducing the absorption of cadmium by plants.
TABLE 6 Cotton yield composition
As can be seen from Table 6, the number of bolls per plant and the weight of bolls per plant were increased and the yield of crops could be increased by applying the soil conditioner for cadmium contamination of the present invention.
TABLE 7 soil available cadmium content (unit: mg. kg)-1)
As can be seen from Table 7, the cadmium activity can be effectively reduced for a long time after the cadmium-contaminated soil conditioner is applied, so that the effective cadmium in the soil can be kept in a low content state.
4. Example 4
In 2017, the field low-cadmium test was carried out at the agricultural college of rock river university (N44 degrees 18 '42.37', E86 degrees 03 '20.72'), the soil type was grey desert soil, and the soil texture was loam. Planting cotton crop, setting 5 mg.kg for experiment-1And (4) cadmium. The cadmium-contaminated soil conditioner of example 4 was applied by drip irrigation for a plurality of times during the development period, in a total amount of 5.73 kg. hm-2. The results are as follows:
TABLE 8 stability of soil aggregates
Fig. 2 is a soil SEM (× 3000)).
As can be seen from fig. 2 and table 8, the MWD, GMA and R0.25 of soil aggregates are significantly increased by 17.24%, 64.05% and 6% and the number of macro aggregates in soil is also significantly increased after applying the cadmium contaminated soil conditioner of the present invention.
TABLE 9 abundance of soil dominant phyla
As can be seen from Table 9, the abundance of Proteobacteria, Acidobacterium and Baculomonas was significantly increased after the soil conditioner for cadmium contamination of the present invention was applied.
The above description is only a preferred embodiment of the present invention, and is not intended to limit the present invention in any way, and any simple modification, equivalent change and modification made to the above embodiments according to the technical spirit of the present invention are within the scope of the technical solution of the present invention.
Claims (8)
1. The cadmium-polluted soil conditioner is characterized by comprising the following raw materials in percentage by weight:
1-7% of polyaluminium chloride, 3-28% of ferric sulfate, 7-28% of calcium hydrophosphate, 35-85% of citric acid, 2-15% of polyacrylamide and 0.5-8% of L-proline; the preparation method of the cadmium-polluted soil conditioner is characterized by comprising the following steps:
(1) sequentially adding polyaluminium chloride, ferric sulfate, calcium hydrophosphate and citric acid into water, and stirring at 60-70 ℃ until the polyaluminium chloride, the ferric sulfate, the calcium hydrophosphate and the citric acid are completely dissolved to obtain a first mixture;
(2) adding polyacrylamide into the first mixture, and stirring at 67-78 ℃ until the polyacrylamide is completely dissolved to obtain a second mixture;
(3) and adding L-proline into the second mixture, and uniformly stirring to obtain the cadmium-polluted soil conditioner.
2. The soil conditioner for cadmium contamination according to claim 1, wherein,
the content of the polyaluminium chloride is 2 to 5 percent;
the content of ferric sulfate is 7% -23%;
the content of the calcium hydrophosphate is 7 to 23 percent;
the citric acid content is 40% -75%;
the content of the polyacrylamide is 3% -11%;
the content of the L-proline is 1% -5%.
3. The cadmium-contaminated soil conditioner according to claim 1, wherein in the preparation method,
in the step (1), after each component is completely dissolved, the next component is added.
4. The cadmium-contaminated soil conditioner according to claim 1, wherein in the preparation method,
in the step (1), the total stirring time is 25-65 min;
in the step (2), the stirring time is 8-25 min.
5. The cadmium-contaminated soil conditioner according to claim 1, wherein in the preparation method,
the volume ratio of the total mass of the polyaluminium chloride, the ferric sulfate, the calcium hydrophosphate, the citric acid, the polyacrylamide and the L-proline to the water is 25-35 g: 1L;
the content of the polyaluminium chloride is 2 to 5 percent;
the content of ferric sulfate is 7% -23%;
the content of the calcium hydrophosphate is 7 to 23 percent;
the citric acid content is 40% -75%;
the content of the polyacrylamide is 3% -11%;
the content of the L-proline is 1% -5%.
6. The soil conditioner for cadmium contamination according to claim 5, wherein,
the fineness of the ferric sulfate, the calcium hydrophosphate and the citric acid is 20-50 meshes;
the volume ratio of the total mass of the polyaluminium chloride, the ferric sulfate, the calcium hydrophosphate, the citric acid, the polyacrylamide and the L-proline to the water is 30 g: 1L of the compound.
7. A method for improving cadmium-contaminated soil is characterized in that,
applying the cadmium-contaminated soil conditioner of claim 1;
adopting drip irrigation, micro-spraying and flushing modes, and applying the fertilizer into soil once or in multiple times along with water; wherein the content of the first and second substances,
the total cadmium content of the soil is less than 0.6 mg/kg-1The application amount of the modifying agent is 3kg hm-2；
The total cadmium content of the soil is 0.6-7 mg/kg-1The application amount of the modifying agent is 3-7 kg.hm-2；
The total cadmium content of the soil is more than 7 mg/kg-1The application amount of the modifying agent is 7-10 kg.hm-2。
8. The method for improving cadmium-contaminated soil according to claim 7, wherein,
the cadmium-polluted soil conditioner can be applied to soil holes at one time or irrigated along with water ditches by adopting hole application and ditch irrigation.
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| CN112024584A (en) * | 2020-07-23 | 2020-12-04 | 湖南农业大学 | Cadmium-polluted soil treatment device and method |
| CN114393024B (en) * | 2022-01-19 | 2023-01-20 | 生态环境部南京环境科学研究所 | Method for stabilizing arsenic, cadmium and zinc in polluted soil by using calcium chloroaluminate |
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