阅读说明：本技术 一种盐碱化土壤的修复工艺及其应用 (Restoration process of salinized soil and application thereof ) 是由 杨鹤峰 卜繁婷 肖满 万鹏 马志强 王轶嘉 于 2020-06-03 设计创作，主要内容包括：本发明属于土壤修复技术领域,具体涉及一种盐碱化土壤的修复工艺及其应用。该工艺包括对耕作层土壤进行预处理；修建围堰、起垄、修建导排沟；对土壤进行第一次灌水,经第一静置后排水；添加钝化剂后对土壤进行第二次灌水,然后打浆直至土壤形成均匀的悬浊液,第二静置后排水。本发明提出了一种盐碱地脱盐、重金属去除与重金属钝化结合的复合工艺,该工艺可以有效降低土壤盐碱度和重金属有效态含量,有助于土壤的改良和钝化效果；该修复工艺通过修建围堰优化修复反应的水环境条件、提高药剂在修复范围分布的均匀性和投加剂量的准确性,有助于控制土壤在理想的酸碱度和离子浓度的溶液中溶出过量盐分及部分目标重金属,降低了土壤的盐度和碱度。(The invention belongs to the technical field of soil remediation, and particularly relates to a remediation process for salinized soil and application thereof. The process comprises pretreating the soil of the plough layer; constructing cofferdams, ridging and constructing drainage channels; carrying out first irrigation on the soil, and draining after first standing; adding a passivating agent, irrigating the soil for the second time, pulping until the soil forms a uniform suspension, and discharging water after standing for the second time. The invention provides a composite process combining saline-alkali soil desalination, heavy metal removal and heavy metal passivation, which can effectively reduce the salinity and alkalinity of soil and the content of effective states of heavy metals and is beneficial to the improvement and passivation effects of the soil; according to the restoration process, the water environment condition of restoration reaction is optimized by building the cofferdam, the distribution uniformity of the medicament in the restoration range and the accuracy of the adding dosage are improved, the excessive salt and part of target heavy metal dissolved out from the soil in the solution with ideal pH value and ion concentration are favorably controlled, and the salinity and alkalinity of the soil are reduced.)

1. A saline-alkali soil restoration process is characterized by comprising the following steps,

pretreating the soil of the plough layer to keep the water content of the soil at 65-75%;

constructing cofferdams, ridging and constructing drainage channels;

carrying out first irrigation on the soil until the water surface is at least 20cm higher than the ground surface, and carrying out first drainage after the soil is stood for the first time;

adding a passivating agent, performing secondary irrigation on the soil until the water surface is 5-10cm higher than the ground surface, pulping until the soil forms uniform suspension, standing for the second time, and performing secondary drainage.

2. The process for remediating saline-alkali soil as claimed in claim 1, further comprising the step of uniformly spreading a chemical into the soil after the first watering and before the first standing;

the mass ratio of the medicament to the dry weight of the soil is (0.001-0.005): 1.

3. the process for remediating saline-alkali soil as recited in claim 2, wherein the agent comprises a weakly acidic modifier and an iron-based agent.

4. The process for remediating saline and alkaline land soil as claimed in any one of claims 1 to 3, wherein the passivating agent comprises at least one of an iron-based agent, an alkaline soil conditioner, a natural mineral passivating agent, a bio-organic matter and a natural mineral soil texture improver.

5. The saline-alkali soil remediation process of any one of claims 1 to 4, wherein the mass ratio of the dosage of the passivating agent to the dry weight of the soil is (0.005-0.05): 1.

6. the process for remediating saline-alkali soil according to any one of claims 1 to 5, wherein the ratio of the height of the cofferdam to the thickness of the plough layer is (1.5-2): 1, the ratio of the width of the upper bottom surface of the cofferdam to the thickness of the plough layer is (1-1.3) to 1; the slope coefficient of the cofferdam is 1-1.5.

7. The saline-alkali soil remediation process of any one of claims 1 to 6, wherein the ratio of the width of the drainage guide channel to the thickness of the plough layer is (1-1.3):1, and the ratio of the depth of the drainage guide channel to the thickness of the plough layer is (1.1-1.4): 1.

8. the saline-alkali soil remediation process of any one of claims 1 to 7, wherein after the first drainage, the water content of the soil is 60% to 80%;

after the second drainage, the height of the water surface is 4-6cm away from the ground surface;

the pulping depth is 0-20 cm.

9. The process for remediating saline-alkali soil as recited in any one of claims 1 to 8, wherein the thickness of the plough layer is 0 to 20cm, but not 0.

10. A method for planting a plant, characterized in that the soil is restored by the restoration process according to any one of claims 1 to 9 before planting seedlings, and then the seedlings are planted.

Technical Field

The invention belongs to the technical field of soil remediation, and particularly relates to a remediation process for salinized soil and application thereof.

Background

With the rapid increase of economy in China and the overall quality of soil environment being not optimistic, according to the national soil pollution condition survey bulletin issued by the ministry of environmental protection 2014, the national soil point standard exceeding rate is 19.4%, wherein the cadmium (Cd) standard exceeding rate reaches 7%. The saline soil is one of the most main intermediate-property soil types in China, is an important reserve land resource in China, has high change speed of the area and the quality of the saline soil, is strongly influenced by human factors, and can cause soil degradation due to improper irrigation, excessive cutting, excessive use of chemical fertilizers and the like, so that secondary salinization occurs on excellent cultivated lands.

At present, the quality of the cultivated land environment in China is great, the security of agricultural products and the health threat of human bodies in the state are caused by the heavy metal pollution of farmland soil, and the characteristics of concealment, long-term property, irreversibility and the like of the heavy metal pollution are the key points which are not negligible in the soil pollution prevention and treatment process. According to the characteristic that the combination potential of the effective state and soil particles is less than the absorption potential of a plant root system, the method is matched with the characteristic that passivation materials are scattered in farmlands in farming, so that the effective state content of heavy metal in the soil is reduced, and the purposes of reducing the content of heavy metal elements enriched by plants and not influencing normal agricultural production are achieved. At present, the research on the remediation of the heavy metal contaminated farmland soil is mostly directed at acid soil, and the research on the passivation of the salinized soil is relatively less.

In the process of passivating and repairing the salinized soil, the desalting and alkalization of the soil, the passivation of heavy metals in the soil and the guarantee of soil fertility are focused; factors affecting the remediation effect include two aspects of soil remediation-improving materials and processes: the concrete steps of construction and technical parameters of the construction process influence the dosage accuracy and the area accuracy of the adding of the repairing-improving material, and further influence the final repairing-improving effect; meanwhile, the coordinated matching of the step of applying the medicament, the step of mixing the medicament and the soil and the step of irrigating the paddy field not only influences the final effect of the repairing-improving material, but also influences the crop yield in the aspects of soil loosening degree (soil permeability), medicament reaction (anaerobic-aerobic environment), medicament residue (heterogeneous influence) and the like. In conclusion, the chemical proportion of the repair-improvement material is an important part influencing the passivation effect, but the construction process is the key for determining whether the repair-improvement effect can be realized in engineering practice.

Disclosure of Invention

Therefore, the technical problem to be solved by the invention is to overcome the defects of high salt content and alkalinity of saline-alkali soil, easy soil hardening in the construction process and the like in the prior art, thereby providing a restoration process of saline-alkali soil and application thereof.

Therefore, the invention provides the following technical scheme.

The invention provides a process for restoring saline-alkali soil, which comprises the following steps,

pretreating the soil of the plough layer to keep the water content of the soil at 65-75%;

constructing cofferdams, ridging and constructing drainage channels;

carrying out first irrigation on the soil until the water surface is at least 20cm higher than the ground surface, and carrying out first drainage after the soil is stood for the first time;

adding a passivating agent, performing secondary irrigation on the soil until the water surface is 5-10cm higher than the ground surface, pulping until the soil forms uniform suspension, standing for the second time, and performing secondary drainage.

The pre-treatment comprises the steps of,

clearing up the soil by using straws and weeds, and removing plant remains and root systems in the restoration layer by means of plowing and the like;

the land is leveled by adopting equipment such as a plowing machine and the like, obvious potholes in the cultivated land are leveled, the surface soil is exposed, no obvious potholes exist in the cultivated land,

and (3) performing flood irrigation on the soil, maintaining the water content of the soil to be more than 90% after gravity water release, leveling the field by adopting a ground hanging machine, and then continuously standing for water release until the water content of the soil is maintained to be 65-75%.

After the first watering and before the first standing, the method also comprises the step of uniformly spreading a medicament into the soil;

the mass ratio of the medicament to the dry weight of the soil is (0.001-0.005): 1.

the medicament comprises a weakly acidic regulator and an iron-based medicament.

The passivator comprises at least one of an iron-based agent, an alkaline soil conditioner, a natural mineral passivator, a biological organic matter and a natural mineral soil texture improver.

The mass ratio of the dosage of the passivating agent to the dry weight of the soil is (0.005-0.05): 1.

the medicament is a weak acid mixed medicament, and comprises a weak acid regulator and an iron medicament; the weak acid regulator comprises at least one of citric acid, oxalic acid, carbonic acid and the like; the iron-based chemical comprises FeSO₄、FeCl₂、FeCl₃And the cation in the iron-based chemical is mainly iron.

The passivator comprises at least one of an iron series medicament, an alkaline soil conditioner, a biological organic matter and a natural mineral soil texture improver;

the iron-based chemical comprises FeSO₄、FeCl₂、FeCl₃Etc. and the cation in the iron-based chemical is mainly iron; the alkaline soil conditioner comprises at least one of calcium carbonate, sodium sulfate, calcium oxide and the like; the biological organic matter comprises at least one of activated sludge, organic fertilizer, fermented straw, biological carbon and the like; the natural mineral soil texture improvementThe effective agent comprises at least one of river sand, humus soil, natural zeolite and kaolin.

The mass ratio of the medicament to the dry soil weight is the adding ratio of the medicament, the mass ratio of the passivating agent to the dry soil weight is the adding ratio of the passivating agent, and the adding amount is equal to the soil density multiplied by the repairing area multiplied by the repairing depth multiplied by (1-water content) multiplied by the adding ratio.

The ratio of the height of the cofferdam to the thickness of the plough layer is (1.5-2): 1, the ratio of the width of the upper bottom surface of the cofferdam to the thickness of the plough layer is (1-1.3) to 1; the slope coefficient of the cofferdam is 1-1.5.

The ratio of the width of the guide and drainage channel to the thickness of the plough layer is (1-1.3) to 1, and the ratio of the depth of the guide and drainage channel to the thickness of the plough layer is (1.1-1.4): 1.

further, after the first drainage, the water content of the soil is 60-80%;

after the second drainage, the height of the water surface is 4-6cm away from the ground surface;

the beating depth is 0-20cm, but not 0.

The ratio of the thickness of the plough layer to the height of the water surface higher than the ground surface after adding the medicament and irrigating is 1: (0.75-1.25);

the ratio of the thickness of the plough layer to the height of the water surface higher than the ground surface after the passivant is added and the water is irrigated is 1: (0.25-0.50).

The thickness of the plough layer is 0-20cm, but not 0.

In addition, the invention also provides a planting method of plants, and the soil is repaired by adopting the repairing process before the seedlings are planted.

Performing primary irrigation on the soil until the water surface is at least 20cm higher than the ground surface, standing for 2-3 days, and performing primary drainage by using a drainage guide channel, wherein the process is large-water-pressure salt treatment;

the technical scheme of the invention has the following advantages:

1. the invention provides a saline-alkali soil remediation process, which comprises the following operation steps of pretreating plough layer soil to keep the water content of the soil at 65-75%; constructing cofferdams, ridging and constructing drainage channels; carrying out first irrigation on the soil until the water surface is at least 20cm higher than the ground surface, and carrying out first drainage after the soil is stood for the first time; adding a passivating agent, performing secondary irrigation on the soil until the water surface is 5-10cm higher than the ground surface, pulping until the soil forms uniform suspension, standing for the second time, and performing secondary drainage. The invention provides a compound process combining saline-alkali soil desalination, heavy metal removal and heavy metal passivation, which can effectively reduce the salinity and alkalinity of soil and the content of effective states of heavy metals and is beneficial to the improvement and passivation effect of the soil; according to the repairing process, the accuracy of adding the medicament and the uniformity of distribution in a repairing range can be improved by building the cofferdam, excessive salt and partial target heavy metal of the soil can be dissolved out in a solution with ideal pH value and ion concentration, the salt alkalinity and the effective state content of the heavy metal of the soil are reduced, and the subsequent soil passivation and improvement effects are further enhanced; standing after the salt is pressed under high water pressure can ensure that the medicament and the soil solution fully react, salt ions are fully dissolved and heavy metal ions are fully passivated, meanwhile, solid-liquid separation in a drainage link is controlled through a cofferdam, the salt ions are discharged along with supernatant, and heavy metal complex molecules are passivated and precipitated at the original position; accurate control of field inlet and outlet and standing water quantity can be achieved by building the cofferdam, and the purpose of uniform repair is achieved.

The repair process for the saline-alkali soil provided by the invention makes up the defects that the soil is easy to harden, the passivation effect is poor and the fertility of the passivated soil is reduced after a passivation medicament is applied independently, realizes the rapid and accurate repair of the saline-alkali soil, and ensures the yield and the quality of crops.

The invention can promote the dissolution of excessive salt in the soil by controlling the large hydraulic salt, overcomes the problem that the soil is easy to harden, can overcome the problem of soil hardening caused by construction in the prior art by adding the passivating agent, and achieves the purpose of loosening the soil.

2. According to the saline-alkali soil remediation process provided by the invention, the agent is added in the step of large water pressure salt, which is beneficial to enhancing the removal effect of the salt particles and heavy metals in the soil and simultaneously ensures the fertility of the soil; by adding the passivating agent, the soil fertility lost in the process of high water pressure salt can be supplemented; the auxiliary agricultural equipment is used for loosening soil, improving the air permeability of the soil and promoting the uniform mixing of the soil.

The saline-alkali soil remediation process provided by the invention can realize a good saline-alkali soil remediation effect by combining the process of adding the medicament and the passivator.

The iron-based medicament is added into the medicament and the passivator, so that the medicament and the passivator can effectively fix the effective state of the heavy metal through chemical complexation, physical adsorption and microbial chelation reaction, and the effect of removing the heavy metal in the soil by a repair process is improved.

3. According to the saline-alkali soil remediation process, the stability and the water impermeability of the cofferdam are ensured by controlling the parameters of the cofferdam, so that the water yield, the working period and the construction process of flooding and drainage in the cofferdam are ensured, and the accuracy of adding the medicament is improved; the thickness and the slope coefficient of the cofferdam can ensure the consistency of the water level and the water quantity of the surface water in the processes of adding the medicament and mixing and stirring (pulping), and avoid the influence on the salt pressing effect caused by medicament loss or solution concentration increase caused by water loss in the cofferdam;

the design of the drainage guide channel can increase the replacement rate of water in the cofferdam and inhibit the precipitation reaction of the insoluble salt in the partial dry-wet alternating process.

4. According to the saline-alkali soil remediation process, the problems that a passivator material is difficult to scatter, mix evenly and rework in the construction process are solved, and the purposes of desalting, passivating heavy metals and improving soil fertility are achieved by matching the process with a passivation material.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.

FIG. 1 is a view showing a positional relationship among a plurality of farmlands, cofferdams and drainage channels to be repaired in example 1 of the present invention;

FIG. 2 is a schematic view showing the positional relationship and dimensions of the drainage channels, the cofferdams and the plough layer in the embodiment 1 of the present invention;

reference numerals: 1-a guide and exhaust channel; 2-cofferdam; and 3, plowing the layer.

Detailed Description

The following examples are provided to further understand the present invention, not to limit the scope of the present invention, but to provide the best mode, not to limit the content and the protection scope of the present invention, and any product similar or similar to the present invention, which is obtained by combining the present invention with other prior art features, falls within the protection scope of the present invention.