A method for remediation of soil contaminated by neonicotinoid pesticides and heavy metals

Abstract

The application discloses a neonicotinoid pesticide-heavy metal compound contaminated soil remediation method, which comprises the following steps: after ploughing and leveling the neonicotinoid pesticide-heavy metal compound contaminated soil, applying bottom fertilizer and neonicotinoid pesticide remediation agent in sequence, ploughing and maintaining, and then transplanting grain amaranth seedlings; when the grain amaranth seedlings grow to the present budding stage, spraying a heavy metal activator to adsorb the soil heavy metal. The application can effectively adsorb, extract and degrade the heavy metal and the neonicotinoid pesticide in the neonicotinoid pesticide-heavy metal compound contaminated soil, reduce the heavy metal and the pesticide residue in the soil, and has the advantages of fast remediation speed, good effect, simple operation and large treatment capacity.

Description

TECHNICAL FIELD

[0001] The present application relates to a neonicotinoid pesticide-heavy metal compound contaminated soil remediation method, belonging to the technical field of soil remediation. BACKGROUND

[0002] The pollutants in the current soil environment are becoming diversified and complex, the types of pollutants entering the ecological system increase exponentially over time, and environmental pollution is no longer an ideal state of single pollution, but a compound pollution composed of various pollutants. In the field of agriculture, pesticides and heavy metals appear at a higher rate, so they will exist in most agricultural soil ecosystems at the same time.

[0003] Heavy metals have long-term persistence and are difficult to biodegrade in soil, once they enter the soil ecosystem, they will migrate, enrich and transform, producing various ecological effects of heavy metal pollution.

[0004] Neonicotinoid insecticides occupy an important position in the global insecticide market due to their novel, efficient mode of action and insecticidal activity. The large amount of use inevitably leads to residues in the environment, which has a negative impact on non-target organisms. Soil is the storage and distribution center of neonicotinoid pesticides, and the absorption rate of plant roots to neonicotinoid pesticides is less than 28%, the rest mostly migrates to other environmental media, which has a certain toxic effect on surrounding plants, animals, microorganisms and humans.

[0005] The compound pollution caused by pesticides and heavy metals can cause changes in the genome expression of organisms, cause oxidative stress effects, growth retardation, slow sexual development, and may affect the reproduction of species, the survival rate of larvae, the abundance of species, and the diversity of species. The current remediation technology for contaminated soil in cultivated land includes soil replacement, passivation, phytoremediation and agronomic control. Compared with other remediation technologies, phytoremediation has low treatment cost, simple operation, green environmental protection, and certain effect on soil improvement and soil and water conservation. Moreover, phytoremediation can also be combined with chemical and agronomic measures for implementation, which has important significance for the remediation and management of cultivated soil pollution. SUMMARY

[0006] In view of the defects in the prior art neonicotinoid pesticide-heavy metal compound contaminated soil remediation method, the purpose of the present application is to provide a neonicotinoid pesticide-heavy metal compound contaminated soil remediation method, which combines chemical modification, microbial regulation and plant enrichment to remediate compound contaminated soil, and realizes efficient and rapid remediation of neonicotinoid pesticide-heavy metal compound contaminated soil.

[0007] In order to achieve the above technical purposes, the application provides a neonicotinoid pesticide-heavy metal compound contaminated soil remediation method, which comprises the following steps: after the neonicotinoid pesticide-heavy metal compound contaminated soil is ploughed and leveled, bottom fertilizer and neonicotinoid pesticide remediation agent are applied in sequence, and then the soil is ploughed and maintained, and then seedling amaranth seedlings are transplanted; when the seedling amaranth seedlings grow to the present budding stage, a heavy metal activator is sprayed to adsorb the soil heavy metals; the neonicotinoid pesticide remediation agent is composed of the following components in percentage by mass: 55-65% of potassium persulfate modified straw biochar, 1-5% of microbial agent, 20-30% of humic acid, 1-5% of iron slag powder and 1-10% of limestone powder.

[0008] The application is beneficial to the growth of the subsequent seedling amaranth seedlings by applying the bottom fertilizer to the contaminated soil, and the application of the neonicotinoid pesticide remediation agent can provide a favorable environment for the degradation of the neonicotinoid pesticide, and the change of the contaminated soil environment in the early stage is beneficial to the degradation and enrichment of the subsequent neonicotinoid pesticide and heavy metal, and is also beneficial to the growth of the subsequent seedling amaranth. The selected seedling amaranth is a crop variety type with wide adaptability and strong stress resistance, and the organic acid and enzyme substances in the root exudates of the seedling amaranth have a certain activation effect on the heavy metals such as Cd and Pb in the soil, and the seedling amaranth also has strong heavy metal adsorption and enrichment capacity, fast growth speed and large biomass, and is an advantageous crop for the remediation of heavy metal contaminated soil. The heavy metal activator is sprayed during the growth of the seedling amaranth seedlings, which can activate the heavy metals in the soil, improve the bioavailability of the heavy metals, increase the adsorption amount of the seedling amaranth to the heavy metals in the soil, and also help the growth of the seedling amaranth.

[0009] Meanwhile, the neonicotinoid pesticide remediation agent used in the application promotes the oxidation and decomposition of organic matter by the potassium sulfate modified straw biochar and the iron slag powder, enhances the microbial degradation effect, adjusts the soil physical and chemical properties by the limestone powder and the humic acid, provides a favorable environment for the degradation of the neonicotinoid pesticide, and degrades the pollutants by the microbial agent taking the humic acid as the carbon source and the nitrogen source, through the nitro reduction and hydroxylation reactions in the microbial body to generate CO2 and other small molecules. The synergistic effect among the components is obvious, and the efficient degradation of the neonicotinoid pesticide in the soil is realized.

[0010] Therefore, the technical scheme of the application realizes the economic and efficient remediation of the neonicotinoid pesticide compound heavy metal contaminated soil by the combined remediation of the chemical improvement, microbial regulation and plant enrichment of the contaminated soil.

[0011] As a preferred scheme, the base fertilizer comprises organic fertilizer and nitro compound fertilizer. The organic fertilizer can improve soil structure and maintain soil humidity, increase microbial activity in the soil, help improve soil fertility, and plant residues in the organic fertilizer can provide various nutrients required by plants for the soil. The nitro compound fertilizer contains various nutrients such as nitrogen, phosphorus, and potassium, can provide rapid nutrient supply, promote rapid growth and development of plants, and increase crop yield and quality. The nitro compound fertilizer can also adjust soil pH, and enhance the resistance of plants to diseases and pests. Therefore, the combined use of organic fertilizer and nitro compound fertilizer in the base fertilizer can fully meet the nutrient requirements of crops and provide a good growth environment for crops.

[0012] As a preferred scheme, the spraying amount of the organic fertilizer is 4000-7500 kg / hm 2 ; and the spraying amount of the nitro compound fertilizer is 400-750 kg / hm 2 .

[0013] As a preferred scheme, the heavy metal activator is composed of 95-96 wt% of NTA (nitrilotriacetic acid), 1-5 wt% of sophorolipid, and 0.5-1 wt% of gibberellin. The heavy metal activator provided by the present application is compounded by NTA, sophorolipid, and gibberellin. First, the sophorolipid reduces the interfacial tension between the pollutants and the soil, so that the heavy metal ions are separated from the soil particles, thereby promoting the complexation of NTA with the heavy metals in the soil, improving the bioavailability of the heavy metals, and strengthening the adsorption and enrichment of grain amaranth to the heavy metals in the soil. At the same time, the gibberellin can accelerate the growth of grain amaranth cells, reduce the toxic effects of heavy metals and organic matter on grain amaranth, promote the growth of grain amaranth, and increase the biomass of grain amaranth. Moreover, each component of the heavy metal activator is easily biodegradable, and the heavy metal activator is an economical, efficient, green, and environmentally friendly heavy metal activator. The sophorolipid and gibberellin in the heavy metal activator play an auxiliary role in the activation of heavy metals and the extraction of plants, so a small amount of addition can produce a synergistic effect with NTA. However, when the amount of addition is too large, it will have a negative impact on soil structure, fertility, and plant growth.

[0014] As a preferred scheme, the spraying amount of the heavy metal activator is 450-750 kg / hm 2 . The heavy metal activator of the present application has the effects of promoting the activation of heavy metals, improving the bioavailability of heavy metals, and strengthening the adsorption and enrichment of plants to heavy metals, but improper application amount will also affect the soil and plants. If too much compound heavy metal activator is applied, the nutrient elements in the soil will be excessively activated and lost, thereby affecting the soil fertility and plant growth; if too little compound heavy metal activator is applied, the heavy metal activation efficiency in the soil is low, the enrichment amount of grain amaranth to the heavy metals in the soil is small, the heavy metal content in the soil decreases slowly, and problems such as poor repair effect and long repair period are caused.

[0015] As a preferred embodiment, the spacing between the amaranth seedlings is (20-30cm) × (20-40cm). In the process of remediating contaminated soil, the spacing between the amaranth seedlings will have a certain impact on the remediation effect. If the spacing is too large, the gaps between plants will be too large, which may affect light and soil cover, thus worsening the soil remediation effect. In addition, excessive gaps can also easily lead to weed growth and soil moisture evaporation, affecting soil moisture retention and plant growth. If the spacing is too small, it means intense competition among plants, which may lead to poor plant growth and, in severe cases, plant death. Furthermore, overly dense planting may also lead to poor soil ventilation, increasing the risk of soil-borne diseases and pests.

[0016] As a preferred embodiment, the transplanting process is as follows: amaranth seedlings are first cultivated in uncontaminated soil, and when the seedlings reach a height of 15-20 cm, they are transplanted with soil attached. This invention, by selecting amaranth seedlings of suitable height for transplanting, not only ensures the survival rate of the transplanted seedlings but also effectively improves their ability to accumulate heavy metals.

[0017] As a preferred embodiment, the application rate of the neonicotinoid pesticide remediation agent is 2000–4500 kg / hm². 2 The application rate of neonicotinoid pesticide remediation agents in this invention has a certain impact on the remediation effect. If the application rate of the remediation agent is too low, the decomposition of neonicotinoid pesticides in the soil will be slow, and the degradation capacity of microorganisms will be limited; while if the application rate of the remediation agent is too high, the limestone powder and iron slag in the remediation agent may have an adverse effect on the physical and chemical properties and structure of the soil, thereby causing soil compaction, and excessive remediation will increase the remediation cost.

[0018] As a preferred embodiment, the neonicotinoid pesticide remediation agent is obtained by uniformly mixing raw materials including potassium persulfate modified straw biochar, rhizobium microbial inoculant, humic acid, iron slag powder, and limestone powder.

[0019] As a preferred option, the straw is at least one of corn straw, rice straw, wheat straw, and sorghum straw.

[0020] As a preferred option, the microbial agent is at least one of the following: Proteobacterium microbial agent, Actinobacterium microbial agent, Rhizobium microbial agent, and Bacillus aeruginosa microbial agent.

[0021] As a preferred embodiment, the potassium persulfate modified straw biochar is obtained by shaking and mixing straw biochar and potassium persulfate solution and then drying; the straw biochar is obtained by anaerobic carbonization treatment of corn straw.

[0022] As a preferred scheme, the mass ratio of the straw biochar and the potassium persulfate solution is (0.5-3):(1-5).

[0023] As a preferred scheme, the condition of the anaerobic charring treatment is that the temperature is 300-500 DEG C and the time is 2-3h. By controlling the temperature and time of the anaerobic charring treatment, the straw can be fully carbonized.

[0024] As a preferred scheme, the anaerobic charring treatment passes in the carbon dioxide with a flow of 80-100ml / min as a reaction atmosphere.

[0025] Compared with the prior art, the technical scheme of the present application has the beneficial technical effects:

[0026] 1) The present application can effectively carry out the adsorption, extraction and degradation of heavy metals and neonicotinoid pesticides in the soil with neonicotinoid pesticide-heavy metal composite pollution, reduce the heavy metal and pesticide residues in the soil, has the characteristics of fast repair speed, good effect, simple operation, large treatment capacity, easy to master by artificial, etc., provides an effective method for large-area repair of neonicotinoid pesticide-heavy metal composite pollution soil.

[0027] 2) The heavy metal activator provided by the present application reduces the interfacial tension between the pollutants and the soil through sophorolipid, makes the heavy metal ions separate from the soil particles, thereby promoting the complexation of NTA and soil heavy metals, improving the biological availability of heavy metals, and strengthening the adsorption and enrichment of grain amaranth on soil heavy metals. At the same time, gibberellin can accelerate the growth of grain amaranth cells, reduce the toxic effect of heavy metals and organic matter on grain amaranth, promote the growth of grain amaranth, and improve the biomass of grain amaranth.

[0028] 3) The present application realizes the economic and efficient repair of neonicotinoid pesticide composite heavy metal contaminated soil through the combined repair of special neonicotinoid pesticide repair agent, grain amaranth and heavy metal activator, chemical improvement, microbial regulation and plant enrichment of contaminated soil. DETAILED DESCRIPTION

[0029] The following examples only specifically describe the preferred embodiments of the present application, and do not limit the scope of the present application. For those skilled in the art, improvements made without departing from the present application should be considered within the protection scope of the present application.

[0030] The compound heavy metal and compound contaminated soil of the neonicotinoid pesticide used in the examples and comparative examples of the present application is the surface soil of a certain vegetable base in Changsha County. The collected soil is broken, sieved to remove large particles, mixed uniformly, and then a soil mixture sample is collected for detection: the soil pH is 5.65; the imidacloprid content is 2.344 mg / kg; and the cadmium content is 0.382 mg / kg. A vegetable planting pot with a size of 50 cm x 40 cm x 28 cm is selected, and 50 kg of the compound contaminated soil is placed in each pot.

[0031] The seedling cultivation method of the Amaranthus hypochondriacus planted in the present application is as follows:

[0032] A piece of uncontaminated dry field is plowed and leveled, and then a drainage ditch is opened after four weeks. 60 kg of organic fertilizer and 6 kg of nitro compound fertilizer are applied as base fertilizer, and then plowed and mixed uniformly. 100 g of high-quality American Amaranthus hypochondriacus (K472) seeds are uniformly sown, and a thin layer of soil is lightly covered. The seedlings are 8-10 cm high (two-leaf stage) and need to be thinned, and gradually thinned to single plants. According to the actual situation, weed control, insect prevention, and irrigation management are done well. When the seedlings are 15-20 cm high (four-leaf stage), they are transplanted with mud.

[0033] The preparation method of the neonicotinoid pesticide repair agent in the present application is as follows:

[0034] The corn straw is washed, dried to constant weight, crushed to powder, and sieved through a 60-mesh sieve; the straw powder is put into a tubular atmosphere furnace, and is heated to a target temperature of 400℃ at a temperature rising rate of 20±0.5℃ / min; carbon dioxide with a flow rate of 80 ml / min is introduced into the tubular atmosphere furnace as the reaction atmosphere; after the tubular atmosphere furnace is cooled to room temperature, it is taken out and sieved through a 100-mesh sieve to obtain corn straw biochar.

[0035] 270 g of potassium persulfate is taken and prepared into a 1.0 mol / L potassium persulfate aqueous solution, and the prepared straw biochar is added to the solution. The straw biochar and the potassium persulfate aqueous solution are mixed uniformly at a mass ratio of 1:1, and are oscillated at 25℃ for 10 hours to prepare potassium persulfate modified straw biochar. -1 )10 hours at 25℃ to prepare potassium persulfate modified straw biochar.

[0036] 10.0 g of rhizobium microbial inoculant, 45.0 g of humic acid, 5.0 g of iron slag powder, 10.0 g of limestone powder, and 130.0 g of potassium persulfate modified straw biochar are weighed and mixed uniformly to obtain 200 g of neonicotinoid pesticide repair agent, which is denoted as T1.

[0037] 10.0 g of rhizobium microbial inoculant, 50.0 g of humic acid, 10.0 g of iron slag powder, 20.0 g of limestone powder, and 110.0 g of potassium persulfate modified straw biochar are weighed and mixed uniformly to obtain 200 g of neonicotinoid pesticide repair agent, which is denoted as T2.

[0038] The preparation method of the heavy metal activator is as follows:

[0039] Take 95g of NTA, 4g of acid-type sophorolipid powder, and 1g of gibberellin, mix uniformly to obtain 100g of the composite heavy metal activator, denoted as S1.

[0040] Take 96g of NTA, 3g of acid-type sophorolipid powder, and 1g of gibberellin, mix uniformly to obtain 100g of the composite heavy metal activator, denoted as S2.

[0041] Example 1

[0042] Apply 130g of organic fertilizer (4000kg / hm 2 ) and 12g of nitro compound fertilizer (400kg / hm 2 ) as base fertilizer to each pot of composite contaminated soil, apply 80g of neonicotinoid pesticide remediation agent T1 (4000kg / hm 2 ), mix uniformly after plowing, and then water and maintain for 2-3 days; transplant 2 seed amaranth seedlings at a spacing of 20cm x 20cm, and perform normal weeding, pest prevention, and drainage and irrigation management; when the seed amaranth grows to the present budding stage, spray 13g of the composite heavy metal activator S1 (650kg / hm 2 ) diluted 1000 times on the soil surface; after the seed amaranth grows for 90 days, collect soil and plant samples for detection.

[0043] Example 2

[0044] Apply 130g of organic fertilizer (4000kg / hm 2 ) and 12g of nitro compound fertilizer (400kg / hm 2 ) as base fertilizer to each pot of composite contaminated soil, apply 80g of neonicotinoid pesticide remediation agent T2 (4000kg / hm 2 ), mix uniformly after plowing, and then water and maintain for 2-3 days; transplant 2 seed amaranth seedlings at a spacing of 20cm x 20cm, and perform normal weeding, pest prevention, and drainage and irrigation management; when the seed amaranth grows to the present budding stage, spray 13g of the composite heavy metal activator S2 (650kg / hm 2 ) diluted 1000 times on the soil surface; after the seed amaranth grows for 90 days, collect soil and plant samples for detection.

[0045] Comparative Example 1

[0046] The difference between this comparative example and Example 1 is that no seed amaranth is planted, no neonicotinoid pesticide remediation agent is added, and no heavy metal activator is sprayed, and the remaining conditions are consistent; after 90 days, soil samples are collected for detection.

[0047] Comparative Example 2

[0048] The difference between the comparative example and example 1 is only that no neonicotinoid pesticide repair agent is added and no heavy metal activator is sprayed, and the rest is consistent, and after the amaranth grows for 90 days, the soil and plant samples are collected for detection.

[0049] Comparative example 3

[0050] The difference between the comparative example and example 1 is only that no heavy metal activator is sprayed, and the rest is consistent, and after the amaranth grows for 90 days, the soil and plant samples are collected for detection.

[0051] Comparative example 4

[0052] The difference between the comparative example and example 1 is only that no neonicotinoid pesticide repair agent is added, and the rest is consistent, and after the amaranth grows for 90 days, the soil and plant samples are collected for detection.

[0053] Comparative example 5

[0054] The difference between the comparative example and example 1 is only that 30g of neonicotinoid pesticide repair agent T1 (1500kg / hm 2 ) is added, and the rest is consistent, and after the amaranth grows for 90 days, the soil and plant samples are collected for detection.

[0055] Comparative example 6

[0056] The difference between the comparative example and example 1 is only that 8g of heavy metal activator S1 (400kg / hm 2 ) is sprayed, and the rest is consistent, and after the amaranth grows for 90 days, the soil and plant samples are collected for detection.

[0057] The soil and plant samples collected in examples 1-2 and comparative examples 1-6 are detected, and the results are shown in Table 1.

[0058] Table 1 Detection results of soil and plant samples collected in examples 1-2 and comparative examples 1-6

[0059]

[0060] From Table 1, it can be seen that:

[0061] The contaminated soil in examples 1-2 is repaired by the repair method of the application, the enrichment ability of amaranth to cadmium is obviously improved, the contents of imidacloprid and cadmium in the soil are effectively reduced, and the repair effect is obvious.

[0062] Comparative example 1 is used as a blank control, only bottom fertilizer and normal field management are applied to the contaminated soil, and it can be seen that the indicators before and after soil repair change little.

[0063] Comparative Example 2 only plants amaranth, and does not apply neonicotinoid pesticide remediator and composite heavy metal activator to the contaminated soil, so the content of imidacloprid and cadmium in the contaminated soil slightly decreases, but the remediating effect is not obvious; and the soil pH environment is not improved, and the enrichment of amaranth to cadmium is not obvious.

[0064] Comparative Example 3 does not apply composite heavy metal activator to the contaminated soil, although the content of imidacloprid in the soil decreases to 1.196 mg / kg, but the enrichment ability of amaranth to cadmium is obviously lower than that of the examples, and the content of cadmium in the contaminated soil does not obviously decrease.

[0065] Comparative Example 4 does not apply neonicotinoid pesticide remediator to the contaminated soil, although the content of cadmium in the soil obviously decreases, but the degradation of imidacloprid in the soil is not obvious, and the remediating effect is poor, and the enrichment ability of amaranth to cadmium is higher than that of Comparative Examples 2-3, but is still lower than that of the examples, which reflects that the neonicotinoid pesticide remediator has a synergistic effect on the bioavailability of amaranth.

[0066] Comparative Examples 5-6 respectively reduce the application amount of neonicotinoid pesticide remediator and heavy metal activator, so the degradation efficiency of imidacloprid in the soil of Comparative Example 5 obviously decreases, the enrichment ability of amaranth to cadmium in the soil of Comparative Example 6 obviously decreases, and the remediating of cadmium in the soil obviously decreases.

[0067] In summary, the above-mentioned combination of remediating measures has obvious remediating effect on the neonicotinoid pesticide-heavy metal composite contaminated soil, and has the characteristics of fast remediating speed, good effect, simple operation, large treatment capacity, easy to be mastered by artificial, and the like, and provides an effective method for remediating large-area neonicotinoid pesticide-heavy metal composite contaminated soil.

Claims

1. A method for remediating soil contaminated with neonicotinoid pesticides and heavy metals, characterized in that: After tilling and leveling the soil contaminated with neonicotinoid pesticides and heavy metals, base fertilizer and neonicotinoid pesticide remediation agent were applied in sequence, followed by tilling and maintenance, and then amaranth seedlings were transplanted; when the amaranth seedlings grew to the budding stage, a heavy metal activator was sprayed to adsorb heavy metals in the soil; The neonicotinic acid pesticide remediation agent is composed of the following components by mass percentage: 55-65% potassium persulfate modified straw biochar, 1-5% microbial inoculant, 20-30% humic acid, 1-5% iron ore slag powder, and 1-10% limestone powder; The heavy metal activator is composed of 95-96 wt% NTA, 3-4 wt% sophorolipid and 1 wt% gibberellin; The application rate of the neonicotinoid pesticide remediation agent is 2000~4500 kg / hm². 2 ; The application rate of the heavy metal activator is 450~750 kg / hm. 2 .

2. The method for remediating soil contaminated with neonicotinoid pesticides and heavy metals according to claim 1, characterized in that: The base fertilizer includes organic fertilizer and nitro compound fertilizer; The application rate of the organic fertilizer is 4000~7500 kg / hm. 2 ; The application rate of the nitro compound fertilizer is 400-750 kg / hm². 2 .

3. The method for remediating soil contaminated with neonicotinoid pesticides and heavy metals according to claim 1, characterized in that: The spacing between the seed amaranth seedlings is (20~30cm) × (20~40cm).

4. A method for remediating soil contaminated with neonicotinoid pesticides and heavy metals according to claim 1 or 3, characterized in that: The transplanting process is as follows: the seedlings of amaranth are first raised in uncontaminated soil, and when the seedlings are 15-20cm tall, they are transplanted with soil attached.

5. The method for remediating soil contaminated with neonicotinoid pesticides and heavy metals according to claim 1, characterized in that: The potassium persulfate modified straw biochar is obtained by shaking and mixing straw biochar and potassium persulfate solution and then drying; the straw biochar is obtained by anaerobic carbonization treatment of corn straw.

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