Method for repairing polycyclic aromatic hydrocarbon polluted soil by chemically enhanced plants

Abstract

The invention relates to the technical field of facility agriculture organic contaminated soil phytoremediation, in particular to a method for chemically enhancing phytoremediation of polycyclic aromatic hydrocarbon contaminated soil. A surfactant alkyl glycoside is added into the polycyclic aromatic hydrocarbon contaminated soil in facility agriculture, and green manure plants are planted for winter grazing. The solubilizing effect of the surfactant is utilized to promote the release of the adsorbed polycyclic aromatic hydrocarbon in the soil to the soil solution and improve the bioavailability of the soil, and then the content of the polycyclic aromatic hydrocarbon in the soil is removed or obviously reduced through the combined action of absorption in the winter grazing growth process, root exudates and microbial degradation. By adopting the green manure plant, the polycyclic aromatic hydrocarbon contaminated soil can be restored, a large amount of green manure can be provided for facility soil, the facility agriculture soil environment performance is improved, the problems of facility agriculture soil degradation and continuous cropping obstacles are effectively relieved, and sustainable production of facility agriculture is guaranteed.

Description

Technical Field

[0001] The invention relates to the research field of restoration of polycyclic aromatic hydrocarbons-contaminated soil in facility agriculture, and specifically is a method for restoring polycyclic aromatic hydrocarbons-contaminated soil in facility agriculture by strengthening winter grazing of gramineous plants using surfactant alkyl glycoside. Background Art

[0002] Since facility agriculture can greatly improve the level of productivity, my country's facility agriculture has been developed on a large scale in recent years. Facility cultivation improves the shortcomings of traditional agricultural production affected by seasons and greatly increases crop yields. However, with the rapid development of industry and agriculture and the acceleration of urbanization, soil organic pollution has become increasingly serious, causing soil degradation and continuous cropping obstacles. At the same time, the accumulation and pollution of soil organic pollutants are aggravated during the application of large amounts of fertilizers, organic fertilizers and pesticides. Polycyclic aromatic hydrocarbons (PAHs), as a typical persistent organic pollutant, have been widely concerned since their discovery. The content and distribution of PAHs in the soil environment are closely related to human activities. The pollution of PAHs in agricultural soil in my country is relatively serious, with an average residual value of 993.0 μg / kg. The content of PAHs in agricultural soil in the northwest region is the highest, reaching 3836.5 μg / kg. Since PAHs are not easily degraded in the soil environment and have a long half-life, they can be bioaccumulated and biomagnified through the food chain, endangering biological communities, vegetation and crops, and ultimately leading to direct or indirect human exposure to pollutants, threatening ecological security and human health.

[0003] Therefore, seeking safe, green and efficient methods for remediation of PAH pollution in facility agriculture soil is an effective way to ensure the sustainable development of facility agriculture and the ecological environment governance of facility agriculture. Due to the large area of ​​moderate and mild PAH-contaminated farmland, from the perspective of economy and promotion, moderate and mild PAH-contaminated farmland is mainly used for safe utilization at this stage. Studies have shown that compared with physical and chemical remediation, phytoremediation technology has the advantages of low cost, no secondary pollution, safety and applicability to large-scale site remediation. However, PAHs in soil have low water solubility and hydrophobicity, are easily adsorbed by soil solid phase, and have low bioavailability. Therefore, how to increase the bioavailability of PAHs and improve the efficiency of phytoremediation has become the research focus in the field of PAH pollution remediation. The method of strengthening phytoremediation by adding surfactants can significantly improve the remediation efficiency of PAHs in contaminated soil. But the key is the screening and combined use of plants and surfactants. Therefore, it is crucial to screen out surfactants that can effectively solubilize PAHs and plants that can effectively absorb and degrade PAHs in soil. In addition, choosing non-edible plants, including green manure plants, as remediation plants not only avoids the harm caused by pollutants entering the food chain during the remediation process, but also green manure plants can provide a large amount of organic green manure for facility agriculture soil improvement while repairing pollutants, effectively alleviating the problems of soil degradation and continuous cropping problems in facility agriculture. Summary of the invention

[0004] The invention aims to provide a method for chemically enhancing phytoremediation of soil contaminated by polycyclic aromatic hydrocarbons.

[0005] To achieve the above object, the present invention provides the following technical solutions: A method for chemically enhanced phytoremediation of polycyclic aromatic hydrocarbons-contaminated soil, characterized in that: surfactant alkyl glycoside is added to facility agricultural soil contaminated with polycyclic aromatic hydrocarbons, and green manure plants winter grazing are planted at the same time, PAHs are desorbed from soil particles through the solubilization effect of alkyl glycoside, and then the absorption and degradation during the growth of winter grazing and the combined effect of rhizosphere microorganisms are utilized to achieve the reduction of PAHs content in facility soil and the removal of PAHs.

[0006] The method for chemically enhanced phytoremediation of polycyclic aromatic hydrocarbons-contaminated soil is characterized in that the concentration of polycyclic aromatic hydrocarbons in the facility agriculture contaminated soil is 100-1000 μg / kg.

[0007] The method for chemically enhanced phytoremediation of polycyclic aromatic hydrocarbons-contaminated soil is characterized in that: before winter grazing, a surfactant alkyl glycoside is added to the contaminated soil and fully mixed, and the amount of alkyl glycoside added is 1.0-5.0 g / kg.

[0008] The method for chemically enhanced phytoremediation of polycyclic aromatic hydrocarbons-contaminated soil is characterized by selecting full, mature, and infested winter forage seeds, placing them in a clean container, and soaking them in clean water at 25°C±5°C for 8-10 hours.

[0009] The method for chemically enhanced phytoremediation of polycyclic aromatic hydrocarbons-contaminated soil is characterized in that: the germinated winter herb seeds are sown in polycyclic aromatic hydrocarbons-contaminated soil added with alkyl glycosides, and then covered with soil to a depth of 1.0-2.0 cm.

[0010] The method for chemically enhanced phytoremediation of polycyclic aromatic hydrocarbons-contaminated soil is characterized in that after winter grazing is planted, regular watering, weeding, and pest control are performed according to conventional management methods of facility agriculture, and the field water holding capacity is maintained at 55-75%.

[0011] The surfactant alkyl polyglycoside used in the present invention is a new type of highly efficient, non-toxic, biodegradable non-ionic surfactant, which is known as a world-class non-toxic surfactant for its superior performance. As a green surfactant, alkyl polyglycoside is of great significance for the remediation of organic pollution in facility agriculture soil.

[0012] The green manure plants used in the present invention are not only rich in nutrition and crude protein for winter grazing, but can also be used as forage to feed livestock and can also be turned over and returned to the field as green manure to improve the soil environment of facility agriculture and increase soil fertility. They have high economic and ecological value.

[0013] The advantages of the present invention are as follows: 1. On the one hand, the present invention utilizes the solubilization effect of surfactant alkyl glycoside on PAHs to promote the release of adsorbed PAHs in the soil into the soil solution, improve their bioavailability, and then effectively remove PAHs in the soil through plant absorption, degradation and synergistic action of microorganisms. On the other hand, surfactant alkyl glycoside can promote plant growth. In this experiment, in the treatment with 3g / kg alkyl glycoside added, the winter herd biomass increased by 35.57% compared with the treatment without alkyl glycoside added. This further promotes the phytoremediation efficiency of PAHs in the soil; 2. The present invention selects winter grazing plants that can be used as green manure plants to absorb and degrade polycyclic aromatic hydrocarbons in the soil. The method is easy to operate, safe and low-cost. The most important thing is that during the winter grazing planting process, it can not only effectively reduce the content of polycyclic aromatic hydrocarbons in the soil, but also can be used as green manure and applied to the soil after being crushed to provide a large amount of organic matter and nutrients for facility soil improvement. While improving soil fertility and soil environmental quality, it reduces the secondary pollution problems that may be introduced during conventional restoration, and at the same time does not affect the normal production of facility agriculture; 3. The present invention applies surfactant alkyl polyglycoside to soil contaminated by PAHs and mixes it evenly before planting winter pasture. When the concentration of PAHs in the soil is 100-1000 μg / kg and 60 days after planting, the PAHs in the contaminated soil are effectively removed through the solubilization effect of surfactant alkyl polyglycoside and the absorption of winter pasture, the interaction of root secretions and rhizosphere microorganisms. When the amount of alkyl polyglycoside added is 3.0 g / kg, the reduction rate of PAHs in the soil is 40.5%, while the reduction rate of PAHs in the treatment of planting winter pasture without adding surfactant is 17.5%, and the reduction rate of PAHs in the control treatment without planting plants and adding surfactant is only 3.75%. The results show that winter pasture has a strong tolerance to PAHs, and alkyl polyglycoside-enhanced winter pasture can effectively reduce PAHs in contaminated soil; 4. The method of using chemical enhanced plants to repair polycyclic aromatic hydrocarbons contaminated soil in the present invention has the advantages of not destroying the site structure, simple operation, low investment, large-scale application, green environmental protection, safety and effectiveness, and is of great significance to the sustainable and efficient utilization of soil resources in facility agriculture. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 The plant biomass diagram of different treatment groups after 60 days provided by the embodiment of the present invention, in which: G1 is a single planting winter grazing treatment; G2 is a 1.0g / kg alkyl glucoside addition + winter grazing treatment; G3 is a 3.0g / kg alkyl glucoside addition + winter grazing treatment; G4 is a 5.0g / kg alkyl glucoside addition + winter grazing treatment; Figure 2 The residual amount and removal rate of polycyclic aromatic hydrocarbons in the soil after 60 days in different treatment groups provided by the embodiment of the present invention. In the figure: G1 is a single planting winter grazing treatment; G2 is a 1.0g / kg alkyl glucoside + winter grazing treatment; G3 is a 3.0g / kg alkyl glucoside + winter grazing treatment; G4 is a 5.0g / kg alkyl glucoside + winter grazing treatment; CK is a no plant planting treatment; Figure 3 This is a graph of plant enrichment coefficients and polycyclic aromatic hydrocarbons content in plants after 60 days in different treatment groups provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0015] A method for chemically enhanced phytoremediation of polycyclic aromatic hydrocarbons-contaminated soil, mainly comprising: By applying surfactant alkyl glycosides to the facility agricultural soil contaminated with polycyclic aromatic hydrocarbons and planting the green manure plant winter pasture, the content of polycyclic aromatic hydrocarbons in the contaminated soil can be effectively removed or continuously reduced through the solubilization effect of alkyl glycosides and the absorption of winter pasture itself during its growth, the interaction between root secretions and rhizosphere microorganisms.

[0016] The method for restoring polycyclic aromatic hydrocarbons-contaminated soil by chemically enhancing plants comprises adding a surfactant alkyl glycoside to the polycyclic aromatic hydrocarbons-contaminated soil and mixing the mixture thoroughly, wherein the amount of the alkyl glycoside added is 1.0-5.0 g / kg.

[0017] The method of using chemical enhanced plants to repair polycyclic aromatic hydrocarbons-contaminated soil is as follows: before planting winter pasture, plump, mature, and infested winter pasture seeds are selected and placed in a clean container, and soaked in 25°C±5°C water for 8-10 hours.

[0018] The method for restoring polycyclic aromatic hydrocarbons-contaminated soil by chemically enhancing plants comprises sowing the germinated winter herb seeds in polycyclic aromatic hydrocarbons-contaminated soil with alkyl glycosides added, and then covering the soil with 1.0-2.0 cm.

[0019] The method of using chemical enhanced plants to repair polycyclic aromatic hydrocarbons contaminated soil is to regularly water, weed and pest control according to conventional management methods of facility agriculture after winter pasture planting, and maintain the field water holding capacity of 55%-75%.

[0020] The method of using chemical enhanced plants to repair polycyclic aromatic hydrocarbons contaminated soil is to harvest plants during their growth period (60-90 days), measure the polycyclic aromatic hydrocarbons content in the above-ground and underground parts of the plants and the polycyclic aromatic hydrocarbons content in the soil, and calculate the reduction rate of polycyclic aromatic hydrocarbons in the soil. The polycyclic aromatic hydrocarbons content in the contaminated soil is effectively removed or continuously reduced through repeated combined action of alkyl glycosides and winter grazing until the polycyclic aromatic hydrocarbons content in the soil reaches the agricultural environmental safety standard. Example

[0021] The following specific examples illustrate the embodiments of the present invention. The following examples can make ordinary technicians familiar with this field understand the present invention more comprehensively, but do not limit the present invention in any way. The experimental site is located in the greenhouse of Shenyang University. The potted test soil is collected from the facility agriculture in Xinmin District, Shenyang City. The typical facility agriculture soil with a planting period of more than 20 years is collected. Its basic physical and chemical properties are pH value 5.80, organic matter content 29.40g / kg, conductivity 578.62μs / cm, cation exchange capacity 355.44cmol / kg, alkaline nitrogen, available phosphorus and available potassium content are 29.07, 52.47 and 206.95 mg / kg respectively, and the background value of polycyclic aromatic hydrocarbons in the soil is 413.17μg / kg, which has a large ecological and health risk. After the potted soil is air-dried, a surfactant alkyl glycoside is added and fully mixed, and the amount of alkyl glycoside added is 1.0-5.0g / kg. Select plump, mature, and infested winter grazing seeds and soak them in 25℃±5℃ water for 8-10h. Then plant the germinated winter grazing seeds in polycyclic aromatic hydrocarbon contaminated soil with alkyl glycosides and cover them with 1.0-2.0cm of soil. Four treatments were set up in the experiment, namely, the winter grazing treatment group (G1) planted alone, the winter grazing treatment group (G2) with 1.0g / kg alkyl glycosides, the winter grazing treatment group (G3) with 3.0g / kg alkyl glycosides, and the winter grazing treatment group (G4) with 5.0g / kg alkyl glycosides. A blank control group (i.e., no plant planting treatment CK) was also set up in the experiment. The experimental pots were round PE plastic pots with a diameter of 20cm and a height of 15cm. The mass of soil in each pot was 1.0kg. 15 winter grazing seeds were evenly sown in the pots. After the growth was stable, the seedlings were thinned to 3 plants / pot. Deionized water was used for irrigation during the growth period. Each treatment was repeated 5 times. During the experiment, the irrigation frequency and water volume were strictly controlled to prevent the loss of PAHs and nutrients in the soil. After 60 days of planting, the aboveground stems and leaves and underground roots of the plants were harvested, and the corresponding planting soil and the control soil without plants were collected to determine the plant biomass and the content of PAHs in the plants and soil.

[0022] High Performance Liquid Chromatograph was used to determine the PAH content in soil and plants. National standard samples and blank samples were used for quality control during the analysis.

[0023] Figure 1The following are the plant biomass of different treatment groups after 60 days. The biomass of winter grazing plants without the addition of alkyl glycosides was 0.71 g / plant. After the addition of alkyl glycosides, the biomass of winter grazing plants increased significantly. When the addition of alkyl glycosides was 3 g / kg, the biomass of winter grazing plants increased by 35.57%. The level of biomass represents the growth and development of plants and their tolerance to pollutants. After the addition of surfactants, the plant biomass increased, indicating that the addition of alkyl glycosides can promote the growth of winter grazing plants.

[0024] Figure 2 Figure 2 shows the PAH residues and removal rates in the soil of different treatment groups after 60 days. G1 was a winter grazing plantation treatment, and the PAH reduction rate in the soil after planting was 17.46%. After adding alkyl glycosides to plant winter grazing, the PAH residues in the soil were significantly reduced. Among them, the PAH reduction rate in the soil of G3 treatment with 3g / kg alkyl glycosides added + winter grazing was 40.53%, while the PAH reduction rate in the control soil without alkyl glycosides added and no plants planted was only 3.75%.

[0025] Figure 3 The content of PAHs in the aboveground and underground parts of winter grazing in different treatment groups after 60 days. The content of PAHs in the roots of winter grazing was significantly higher than that in the aboveground stems and leaves, indicating that PAHs were mainly enriched in the roots of winter grazing, thereby reducing the toxic effects of various organs in the aboveground parts, and also avoiding the harm caused by pollutants in the soil entering the food chain during the phytoremediation process, which is suitable for the remediation of contaminated soil in facility agriculture.

Claims

1. A method for chemically enhanced phytoremediation of polycyclic aromatic hydrocarbons-contaminated soil, characterized in that: The method comprises adding a surfactant alkyl glycoside to the facility agricultural soil polluted by polycyclic aromatic hydrocarbons, and planting the green manure plant winter grazing, utilizing the solubilization effect of the surfactant alkyl glycoside on polycyclic aromatic hydrocarbons, and the combined effect of the absorption of winter grazing, root secretions and microorganisms to remove or significantly reduce the content of polycyclic aromatic hydrocarbons in the facility soil; The concentration of polycyclic aromatic hydrocarbons in the facility agricultural contaminated soil is 100-1000 μg / kg.

2. A method for chemically enhanced phytoremediation of polycyclic aromatic hydrocarbons-contaminated soil according to claim 1, characterized in that: Before planting winter grazing, surfactant alkyl glycoside is added to the PAH-contaminated soil and mixed thoroughly. The amount of alkyl glycoside added is 1.0-5.0 g / kg.

3. A method for chemically enhanced phytoremediation of polycyclic aromatic hydrocarbons-contaminated soil according to claim 1, characterized in that: Select plump, mature, and infested winter herd seeds and soak them in clean water at 25℃±5℃ for 8-10 hours. Then plant the germinated winter herd seeds in polycyclic aromatic hydrocarbon contaminated soil with alkyl glycosides added, and cover with 1.0-2.0 cm of soil.

4. A method for chemically enhanced phytoremediation of polycyclic aromatic hydrocarbons-contaminated soil according to claim 1, characterized in that: After planting winter grazing, follow the conventional management methods of facility agriculture, regularly water, weed and pest control, and maintain the field water holding capacity at 55%-75%.

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