Method for enhancing tolerance and removal effect of restoration plants on herbicide atrazine pollution

Abstract

The invention discloses a method for enhancing tolerance and removal effect of a remediation plant on herbicide atrazine pollution. The remediation plant is an emergent aquatic plant yellow acorus gramineus which is high in atrazine tolerance and has ornamental value. According to the method, graphene oxide is added into a restoration plant growth substrate, and the growth substrate is river sand which is low in organic matter content and weak in graphene oxide adsorption. The method not only can promote the growth of acorus gramineus of the atrazine polluted remediation plant, but also can increase more atrazine entering the plant body to be enriched in the cell wall, thereby reducing the atrazine reaching the target chloroplast which acts on the atrazine, and reducing the phytotoxicity of the atrazine. Moreover, the graphene oxide can also significantly increase the removal rate of atrazine and significantly shorten the half-life period of atrazine in water.

Description

Technical Field

[0001] The invention relates to the technical field of water pollution ecological management, and in particular to a method for enhancing the pollution tolerance and removal effect of restoration plants on the herbicide atrazine. Background Art

[0002] The herbicide atrazine has been used in my country for decades. Because it is not easily photodegraded and its microbial degradation is relatively slow, it is one of the pesticides with the highest detection rate in the water environment, threatening the health of aquatic ecosystems. Atrazine pollution in water bodies is increasingly becoming an environmental problem that needs to be solved urgently.

[0003] Phytoremediation technology mainly uses plants and their coexisting microorganisms as technical means to purify pollutants in the environment. It is low-cost, sustainable, and helps to improve the ecological landscape. It is an environmentally friendly green biotechnology with incomparable advantages over traditional pollution control technologies. It is a technology with great application potential for removing atrazine pollution from water bodies.

[0004] However, phytoremediation technology mainly relies on biological processes, which are slower to take effect and take a long time to repair compared with some commonly used engineering measures. In addition, the toxicity of the target pollutants will also pose a threat to the growth of the repair plants, especially herbicide pollutants, which usually inhibit plant growth and reduce the repair efficiency of plants. Therefore, the current phytoremediation technology that relies solely on the functions of the plants themselves can no longer meet the actual needs of herbicide pollution control, and the combined effects of other synergistic measures must be considered. The ideal synergistic measure is to be able to enhance the tolerance of the repair plants to the stress of pollutants, so that the plants can grow well in the contaminated site and accumulate a higher biomass, and have a better purification effect on pollutants, shortening the treatment time.

[0005] Conventional phytoremediation technology also has a certain purification effect on atrazine pollution in water bodies, but the herbicide atrazine is phytotoxic and will inhibit the growth of remediation plants under long-term stress, thereby limiting the continued effectiveness of phytoremediation and reducing removal efficiency. Summary of the invention

[0006] In view of the deficiencies in the prior art, the present invention provides a method for enhancing the tolerance and removal effect of restoration plants to the herbicide atrazine pollution, which can effectively alleviate the stress of atrazine on restoration plants and improve restoration efficiency.

[0007] In order to achieve the object of the present invention, the technical solution of the present invention is as follows:

[0008] 1. Screening of suitable restoration plants. Based on the ornamental value and the convenience of management and maintenance, common emergent plants were initially selected as the screening objects; and further hydroponic experiments were conducted, using plant growth and physiological characteristics as indicators to screen out the yellow calamus, a plant with strong tolerance to atrazine.

[0009] 2. Determination of synergist and its appropriate addition concentration. The inventors of this patent found that the two-dimensional carbon nanomaterial graphene oxide can not only adsorb atrazine, but also significantly increase the enrichment amount of atrazine on the cell wall of Iris pseudacorus, reduce the amount of atrazine reaching the target site of chloroplast, thereby reducing the stress of atrazine on plants; in addition, it also has a promoting effect on the growth of Iris pseudacorus. By observing the growth and physiological performance of Iris pseudacorus in graphene oxide solutions with different concentrations, the optimal addition concentration of graphene oxide was determined to be 80 mg·L -1 .

[0010] 3. Method for adding synergist. The synergist graphene oxide is added to the plant culture medium. Considering the anchoring effect of the medium on plants and its possible adsorption effect on graphene oxide, which may affect its synergistic effect, river sand with a relatively large specific gravity and low organic matter content is selected as the culture medium.

[0011] 4. Application of the enhanced phytoremediation technology. Using a permeable ceramic cup as the culture container, and river sand added with graphene oxide (the addition amount is 80 mg·kg -1 ) as the culture medium, transplant the pre-cultured adult plants of Iris pseudacorus, and place them in the water to be treated after planting.

[0012] The technical solution of the present invention can specifically be as follows:

[0013] First of all, the present invention provides a method for enhancing the tolerance and removal effect of phytoremediation plants to herbicide atrazine pollution, which is to cultivate phytoremediation plants with a growth medium added with graphene oxide.

[0014] Preferably, the phytoremediation plant is Iris pseudacorus.

[0015] Preferably, the growth medium is river sand.

[0016] Preferably, the addition amount of graphene oxide is 80 mg·L -1 .

[0017] In addition, the present invention also provides a method for treating water body to remove atrazine pollution in the water body, which is to place the phytoremediation plants obtained by the above method in the water body to be treated after planting.

[0018] In an embodiment of the present invention, the concentration of atrazine in the water body treated by the above method can be 0.1 - 2.5 mg·L -1 .

[0019] The beneficial effects of the present invention are as follows:

[0020] The present invention provides a method for enhancing the tolerance and removal effect of plants for atrazine pollution repair. By adding graphene oxide to the growth substrate of Iris pseudacorus, which is a plant for atrazine pollution repair, graphene oxide can not only adsorb atrazine by itself, but also significantly increase the enrichment of atrazine on the cell wall after entering the repair plant, effectively reducing the amount of atrazine reaching its target of action and significantly alleviating the stress of atrazine on the repair plant. Moreover, graphene oxide has an obvious promoting effect on the growth of the repair plant. In summary, graphene oxide can ensure that the repair plant continuously and stably exerts its function of purifying atrazine. Description of the Drawings

[0021] Figure 1 Shows the effects of different concentrations of graphene oxide on the growth of Iris pseudacorus;

[0022] Figure 2 Shows the removal effect and adsorption capacity of graphene oxide for atrazine (0.1, 0.5 and 2.5 mg·L -1 );

[0023] Figure 3 Shows the promoting effect of graphene oxide on the removal of atrazine (0.1 mg·L -1 );

[0024] Figure 4 Shows the atrazine enrichment ratio in different subcellular components of the stems, leaves and roots of Iris pseudacorus;

[0025] Figure 5 Shows the promoting effect of graphene oxide on the removal of atrazine (0.5 mg·L -1 );

[0026] Figure 6 Shows the promoting effect of graphene oxide on the removal of atrazine (2.5 mg·L -1 ); Detailed Embodiments

[0027] The preferred embodiments of the present invention will be described in detail below in conjunction with the embodiments. It should be understood that the following embodiments are given only for the purpose of illustration and are not used to limit the scope of the present invention. Those skilled in the art can make various modifications and substitutions to the present invention without departing from the purpose and spirit of the present invention.

[0028] The experimental methods used in the following embodiments are all conventional methods unless otherwise specified.

[0029] The materials, reagents, etc. used in the following embodiments can be obtained from commercial channels unless otherwise specified.

[0030] Parameter Screening and Determination of the Method for Enhancing the Tolerance and Removal Effect of Remediation Plants to Atrazine Pollution

[0031] I. Screening and Determination of the Appropriate Concentration of Graphene Oxide

[0032] The graphene oxide is a 1.4% suspension with a purity of ≥99%. The graphene oxide culture solutions with concentrations of 1, 20, 80, and 140 mg·L -1 were prepared with 10% Hoagland nutrient solution. Taking the 10% Hoagland nutrient solution without adding graphene oxide as the control, Iris pseudacorus with consistent growth was transferred into conical flasks containing 250 mL of the above-mentioned culture solutions and cultured for 4 weeks. The plants were carefully taken out, washed with deionized water, and then the plant samples were dried in an oven at 65°C for 48 hours until a constant mass was reached. The dry weight was measured with an electronic balance (accuracy of ±0.01 g), and the relative growth rate (RGR) was calculated.

[0033] The results showed that 20, 80, and 140 mg·L -1 graphene oxide significantly promoted the biomass accumulation of Iris pseudacorus ( Figure 1 ). Among them, 80 mg·L -1 was the optimal concentration, which could increase the dry matter weight and relative growth rate of Iris pseudacorus by 84% and 28% respectively.

[0034] II. Determination of the Appropriate Culture Medium Substrate

[0035] Since phytoremediation of atrazine pollution is carried out in water, and the water already contains the basic nutrients required for plant growth, the main function of the substrate is to anchor the plants. Therefore, materials with a relatively large specific gravity should be selected. At the same time, considering that the adsorption of organic matter on graphene oxide will reduce the activity of graphene oxide, the organic matter content of the substrate material should be as low as possible. In summary, river sand has a low organic matter content, uniform particle size composition, round and smooth particles, and is an ideal culture medium substrate.

[0036] III. Removal Effect of Graphene Oxide on Atrazine

[0037] To verify the removal effect of graphene oxide on atrazine, an experiment on the removal of atrazine by graphene oxide was designed. The concentration of graphene oxide was 80 mg·L -1 determined above. For atrazine, a 90% water dispersible granule commonly used in production practice was selected. According to the water pollution monitoring data, the concentrations were designed to be 0.1, 0.5, and 2.5 mg·L -1, using the atrazine solution without adding graphene oxide as the control. Each treatment was set with 3 replicates, and each treatment solution was 50 mL, all placed in a 150 mL Erlenmeyer flask, and the bottle mouth was sealed with a sealing film to prevent water evaporation. All treatments were placed in a constant temperature (25 °C) shaker and run at 120 rpm. The experiment was carried out for a total of 240 min. Water samples were collected at 5, 10, 20, 30, 60, 120, and 240 min respectively. The water samples were filtered through a 0.22 μm filter membrane and centrifuged at 10000 rpm for 20 min to detect the atrazine concentration in the supernatant. The atrazine was extracted by solid-phase extraction, and the atrazine content in each treatment solution was determined by high-performance liquid chromatography. Calculate the removal rate (Formula 1) and adsorption capacity (Formula 2) of graphene oxide for atrazine.

[0038] Atrazine removal rate (%) = (C 0 - C t ) / C 0 × 100% (1)

[0039] q e (mg / g) = V / m × (C 0 - C e ) (2)

[0040] In the formula, V is the volume of the solution (L); m is the mass of graphene oxide (mg); C 0 and C t (mg·L -1 ) are the initial concentration of atrazine and the atrazine concentration of the sample at different sampling times respectively; q e (mg·g -1 ) is the adsorption capacity, and C e (mg·L -1 ) is the equilibrium concentration of atrazine.

[0041] The adsorption rate of graphene oxide for atrazine is relatively fast. When the initial concentration of atrazine is 0.1 mg·L -1 , graphene oxide reaches the maximum adsorption capacity within 5 min; when the initial concentration of atrazine is 0.5 mg·L -1 , graphene oxide reaches the maximum adsorption capacity within 20 min; when the initial concentration of atrazine is 2.5 mg·L -1 , graphene oxide reaches the maximum adsorption capacity within 30 min ( Figure 2 A). The removal rates of graphene oxide for atrazine with initial concentrations of 0.1, 0.5, and 2.5 mg·L -1 are 11.2%, 14.8%, and 19.1% respectively, and the removal rate increases significantly with the increase of the initial concentration of atrazine ( Figure 2In B), the adsorption capacities of graphene oxide for atrazine are 0.19, 0.91, and 6.1 mg·g -1 , respectively, and increase significantly with the increase of the initial concentration of atrazine ( Figure 2 In C).

[0042] Example 2. Treat the polluted water body by using the method of enhancing the tolerance and removal effect of the phytoremediation plant on the herbicide atrazine pollution of the present invention

[0043] Take water samples from the upper, middle, and lower reaches of the river that receives the reclaimed water discharged from the municipal sewage treatment plant and mix them. After measurement, the atrazine concentration is 0.1 mg·L -1 . Mix graphene oxide into the river sand to make the target concentration 80 mg·kg -1 ; Put the river sand mixed with graphene oxide into a permeable ceramic cup with a diameter of 8 cm and a height of 12 cm, and then transplant the Iris pseudacorus cultivated in the greenhouse (the plant height is preferably > 30 cm). One plant is placed in each cup. Put the ceramic cup with the plant into a tray filled with clean water and place it in the greenhouse for cultivation. After about one week, fix the plants. During this period, replenish clean water into the tray every day to keep the tray always in a water-filled state. Put the fixed Iris pseudacorus and the cultivation container together into a plastic bucket with a diameter of 20 cm and a height of 30 cm. Three plants are placed in each bucket. Then add the retrieved river water. The height of the added water should just submerge the ceramic cup. Use the river sand without adding graphene oxide as the culture medium for the control, and the other treatment steps are the same. The treatment lasts for 21 days. Collect plant and culture solution samples at 1, 3, 5, 7, 14, and 21 days of cultivation respectively. Extract atrazine in the samples by solid-phase extraction method, and determine the atrazine concentration in plant and culture solution samples by high-performance liquid chromatography. Use the first-order kinetic model (Formula 3) to simulate the elimination dynamics of atrazine, and calculate the half-life (Formula 4) and removal rate (Formula 5) of atrazine.

[0044] C t = C 0 e -Kt (3)

[0045] T 1 / 2 = (ln2) / K (4)

[0046] Atrazine removal rate (%) = (C 0 -C t ) / C t ×100% (5)

[0047] In the formula, t (days) is the sampling time, C 0 and C t (mg·L –1 ) are the initial concentration of atrazine and the concentration at different sampling times respectively, and K is the atrazine elimination rate constant.

[0048] After the Iris pseudacorus colonized with graphene oxide was treated in the substrate for 7, 14, and 21 days, the atrazine removal rates in the solution were 64.8%, 88.1%, and 93.1% respectively, which were significantly higher than those of the control (p<0.01); the removal rates increased by 21.5%, 15.7%, and 9.3% respectively ( Figure 3 in A). After the Iris pseudacorus colonized with graphene oxide was treated in the substrate for 21 days, the atrazine elimination rate constant increased significantly (p<0.01), and the increase rate was 42.2% ( Figure 3 in B); the half-life of atrazine in water decreased significantly (p<0.01), which was 29.9% shorter than that of the control ( Figure 3 in C).

[0049] Adding 80mg·L -1 graphene oxide significantly increased the enrichment amount of atrazine on the cell walls of the stems, leaves and roots of Iris pseudacorus, and significantly reduced the enrichment amount on the cell organelles ( Figure 4 ). The action target of atrazine is the cell organelle (chloroplast). Therefore, adding graphene oxide can significantly reduce the amount of atrazine reaching the action target, thereby reducing the stress effect of atrazine on plants.

[0050] Example 3. Treating polluted water bodies by using the method of enhancing the tolerance and removal effect of phytoremediation plants on herbicide atrazine pollution of the present invention

[0051] Considering the actual situation, when a large rainfall occurs shortly after atrazine is applied in farmland, the atrazine concentration in the surface runoff is relatively high. According to existing reports, application scenarios with atrazine concentrations of 0.5 and 2.5mg·L -1 were set. By adding 90% atrazine water dispersible granule to the retrieved river water, the target concentrations of atrazine in the river water were 0.5 and 2.5mg·L -1 respectively. The treatment device, graphene oxide addition, phytoremediation plant planting, etc. were the same as in Example 1.

[0052] When the initial concentration of atrazine was 0.5mg·L -1 , the atrazine removal rates of the Iris pseudacorus colonized with graphene oxide in the substrate were higher than those of the control after 3 days of treatment. Among them, the removal rates at 3, 5, 14, and 21 days were 22.6%, 36.9%, 74.3%, and 87.5% respectively, which were significantly higher than those of the control (p<0.05); the removal rates increased by 59.8%, 33.7%, 24.5%, and 10.1% respectively ( Figure 5 in A). After the Iris pseudacorus colonized with graphene oxide was treated in the substrate for 21 days, the atrazine elimination rate constant increased significantly (p<0.01), and the increase rate was 27.7% ( Figure 5In B); the half-life of atrazine in water was significantly shortened (p < 0.01), being shortened by 21.7% compared to the control ( Figure 5 In C).

[0053] When the initial concentration of atrazine was 2.5 mg·L -1 during the 21-day operation, the atrazine removal rates of the treatments with Iris pseudacorus colonized with graphene oxide added to the substrate were all higher than those of the control. Among them, the removal rates at 7, 14, and 21 days were 47.7%, 59.9%, and 72.2% respectively, which were significantly higher than those of the control (p < 0.05); the removal rates were increased by 49.8%, 24.7%, and 16.7% respectively ( Figure 6 In A). After 21 days of treatment with Iris pseudacorus colonized with graphene oxide added to the substrate, the elimination rate constant of atrazine increased significantly (p < 0.01), and the increase rate was 46.8% ( Figure 6 In B); the half-life of atrazine in water was significantly shortened (p < 0.01), being shortened by 31.8% compared to the control ( Figure 6 In C).

[0054] Although the present invention has been described in detail with general descriptions and specific embodiments above, based on the present invention, some modifications or improvements can be made, which are obvious to those skilled in the art. Therefore, these modifications or improvements made without departing from the spirit of the present invention all fall within the scope of protection required by the present invention.

Claims

1. A method for enhancing the tolerance and removal effect of restoration plants to atrazine pollution, which is to cultivate restoration plants using a growth matrix with added graphene oxide.

2. The method according to claim 1, characterized in that The restoration plant is Iris phellodendri.

3. The method according to claim 1, characterized in that The growth substrate is river sand.

4. The method according to claim 1, characterized in that: The addition amount of graphene oxide is 80 mg·L -1 .

5. A method for treating water to remove atrazine pollution, comprising planting the remediation plant obtained by the method according to any one of claims 1 to 4 into the water to be treated.

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