A method for remediation of cadmium and arsenic composite pollution in cultivated land based on artemisia extraction and organic material regulation

Abstract

This invention relates to the field of soil remediation technology, specifically to a method for remediating cadmium-arsenic co-polluted farmland based on Artemisia argyi extract and organic material regulation. The method includes: preparing Artemisia argyi hot water extract to modify organic materials; preparing inner cadmium-activating materials and outer arsenic-controlling materials; applying the two types of materials in sections along the Artemisia argyi planting rows, with the inner strip activating cadmium close to the root zone and the outer strip intercepting arsenic migration; after transplanting the Artemisia argyi, applying a root zone activation solution containing Artemisia argyi extract and citric acid in stages; and after harvesting, applying a composite passivation material and rotary tilling to incorporate it into the topsoil. This invention achieves integrated "remediation-safe utilization" management of cadmium-arsenic co-polluted farmland through spatial synergy of organic material interface modification, local root zone activation, and arsenic migration interception, combined with the temporal switching between activation during the remediation season and passivation during the safe utilization season. This improves the cadmium absorption efficiency of Artemisia argyi while effectively controlling the risk of arsenic migration.

Description

Technical Field

[0001] This invention relates to the field of soil remediation technology, and in particular to a method for remediating cadmium and arsenic compound pollution in arable land based on Artemisia argyi extraction and organic material regulation. Background Technology

[0002] The problem of combined cadmium and arsenic pollution in arable land in southern my country is prominent. Existing remediation technologies are mostly designed for single pollutants, making it difficult to address the contradictory needs of cadmium activation and extraction, and arsenic fixation and control. Traditional phytoremediation often uses hyperaccumulating plants such as Artemisia argyi, but relying solely on plants has limited absorption efficiency. Furthermore, while low-molecular-weight organic acids can enhance cadmium availability, they can easily trigger simultaneous activation and migration of arsenic, increasing risks to groundwater and the surrounding environment. Passivation remediation often employs the full-layer mixing of materials such as biochar, organic fertilizer, or iron salts. Although this can reduce the content of available heavy metals in the short term, it does not consider the dynamic changes in the rhizosphere microenvironment and pollutant speciation. After remediation, the soil may still experience reactivation of heavy metals due to changes in environmental conditions.

[0003] Furthermore, existing remediation models often disrupt the continuity between "remediation and safe utilization," failing to promptly switch control strategies after the remediation season ends, resulting in persistent heavy metal contamination risks during subsequent crop planting. The application of single technologies often leads to unintended consequences; for example, measures to enhance cadmium activation are frequently accompanied by increased arsenic migration risks, while excessive passivation can inhibit plant cadmium absorption efficiency. This makes it difficult to simultaneously achieve remediation effects and ensure the safety of subsequent agricultural production. Therefore, there is an urgent need to develop a comprehensive technical solution that can synergistically regulate cadmium and arsenic behavior and seamlessly integrate remediation and safe utilization. Summary of the Invention

[0004] In view of this, the purpose of this invention is to propose a method for remediating cadmium and arsenic compound pollution in arable land based on Artemisia argyi extraction and organic material regulation, so as to achieve efficient activation and absorption of cadmium and effective interception of arsenic migration in the root zone of Artemisia argyi in cadmium and arsenic compound polluted arable land, and to quickly transform the soil from an activated and remediated state to a state that is safe for subsequent crops after Artemisia argyi harvest.

[0005] To achieve the above objectives, this invention provides a method for remediating cadmium and arsenic compound pollution in arable land based on Artemisia argyi extraction and organic material regulation, comprising the following steps: S1. Taking cadmium-arsenic combined contaminated farmland as the treatment target, Artemisia argyi planting rows are set up in the cadmium-arsenic combined contaminated farmland during the remediation season. S2. A hot water extract of Artemisia argyi for modifying the outer layer of organic materials is obtained by hot water extraction of dried Artemisia argyi and water. Crop straw biochar, commercial organic fertilizer, potassium humate, the hot water extract of Artemisia argyi for modifying the outer layer of organic materials and water are mixed and piled up to obtain Artemisia argyi extract-modified organic materials. S3. The directional modified organic material of Artemisia argyi extract is divided into two parts. One part is mixed with citric acid monohydrate, oyster shell powder and water and piled up to obtain the inner cadmium-activating material. The other part is mixed with polyferric sulfate, oyster shell powder and water and piled up to obtain the outer arsenic migration control material. S4. Set an inner strip along the Artemisia argyi planting row, and apply the inner cadmium activating material into the inner strip; set outer strips on both sides of the inner strip, and apply the outer arsenic migration control material into the outer strip, with the inner edge of the outer strip being 8-12cm away from the edge of the inner strip. S5. Transplant the mugwort seedlings above the inner strip. 40-50 days and 70-80 days after transplanting, extract the mugwort hot water extract from dried mugwort leaves and water respectively to obtain a ready-to-use mugwort hot water extract. Mix the ready-to-use mugwort hot water extract, citric acid monohydrate and water to form a root zone activation solution. Apply the root zone activation solution locally to the root zone of the mugwort. S6. Harvest the above-ground part of the Artemisia argyi 110-130 days after transplanting, and remove the above-ground part of the Artemisia argyi from the cadmium-arsenic contaminated farmland. S7. After the harvest of Artemisia argyi, a hot water extract of Artemisia argyi for immediate use is obtained by hot water extraction of dried Artemisia argyi leaves and water. Commercial organic fertilizer, polyferric sulfate, potassium humate, oyster shell powder, the hot water extract of Artemisia argyi for immediate use and water are mixed and piled up to obtain a safe pre-season passivation material. The safe pre-season passivation material is applied to the cadmium and arsenic compound contaminated farmland after harvest and mixed into the topsoil.

[0006] Preferably, the cadmium-arsenic contaminated farmland is farmland with a total cadmium content of 0.980-1.780 mg / kg, a total arsenic content of 48-82 mg / kg, and a pH of 5.4-6.8 in the 0-20cm topsoil layer. No edible crops are planted during the remediation season; only Artemisia argyi is planted for cadmium activation and absorption and removal from the aboveground parts.

[0007] Preferably, at 667m 2 According to the processing unit, the hot water extract of Artemisia argyi for modifying the outer layer of organic materials is prepared by the following method: 30-40 kg of dried Artemisia argyi leaves are added to 300-400 kg of water and extracted at 75°C for 2 hours. During the extraction, the mixture is stirred once every 20 minutes for 5 minutes each time. After the extraction, the mixture is filtered through an 80-mesh filter cloth. The filter residue is rinsed with 30-40 kg of water and the filtrates are combined. The combined filtrate is concentrated to 200-240 kg at 70°C, or water is added to 200-240 kg if the combined filtrate is less than the target mass, to obtain the hot water extract of Artemisia argyi for modifying the outer layer of organic materials.

[0008] Preferably, at 667m 2According to the processing unit, the directional modified organic material of Artemisia argyi extract is prepared by the following method: 105-150 kg of crop straw biochar, 270-360 kg of commercial organic fertilizer and 25-40 kg of potassium humate are mixed for 20-30 min, then 200-240 kg of hot water extract of Artemisia argyi for modifying the outer layer of organic material and 45-90 kg of water are added, and the mixture is mixed for another 30 min and then piled for 48-60 h. The pile temperature is controlled at 25℃, and the mixture is turned over once every 24 h during the pile period to obtain the directional modified organic material of Artemisia argyi extract.

[0009] Preferably, at 667m 2 According to the processing unit, the inner cadmium-activated material is prepared by the following method: Take 400-500 kg of wormwood extract-modified organic material, add 5-12 kg of citric acid monohydrate, 8-14 kg of oyster shell powder and 70-100 kg of water, mix for 30 min and then pile at 20℃ to 35℃ for 24 h to obtain the inner cadmium-activated material.

[0010] Preferably, at 667m 2 According to the processing unit, the outer arsenic migration control material is prepared by the following method: Take 290-340 kg of wormwood extract-modified organic material, add 20-35 kg of polyferric sulfate, 20-35 kg of oyster shell powder and 80-120 kg of water, mix for 30 min and then pile at 25°C for 48 h to 96 h. During the pile-up period, stir once every 24 h, and the piled material is not sealed to obtain the outer arsenic migration control material.

[0011] Preferably, the width of the inner strip is 22-30cm and the depth is 10-15cm. All the inner cadmium activation material is applied into the inner strip in equal proportions according to the total length of the inner strip, and then covered with 2-5cm of soil. The width of the outer strip is 8-12cm and the depth is 8-15cm. All the outer arsenic migration control material is applied into the outer strip in equal proportions according to the total length of the outer strip, and then covered with soil.

[0012] Preferably, at 667m 2 For each treatment unit, 85-100 kg of Artemisia argyi seedlings are transplanted above the inner strip, with a plant spacing of 25-35 cm, a row spacing of 50-55 cm, and a transplanting depth of 6-10 cm. After transplanting, 400-600 kg of water is applied. Within 15 days after transplanting, the moisture content of the 0-20 cm tillage layer is controlled to 60% to 70% of field capacity. From 15 days after transplanting until harvest, the moisture content of the 0-20 cm tillage layer is controlled to 55% to 70% of field capacity.

[0013] Preferably, at 667m 2The preparation of the root zone activation solution for each treatment unit includes: adding 1.6-2.4 kg of dried Artemisia argyi leaves to 16-24 kg of water, extracting at 75°C for 1 hour, filtering through an 80-mesh filter cloth, and adjusting the volume to 8-12 kg to obtain a hot water extract of Artemisia argyi for immediate use. Then, 2-4 kg of citric acid monohydrate, 8-12 kg of the hot water extract of Artemisia argyi for immediate use, and 80-120 kg of water are mixed to obtain the root zone activation solution. The root zone activation solution is applied to the soil surface only along the radius of 8-12 cm from the base of the Artemisia argyi stem.

[0014] Preferably, at 667m 2 For the treatment unit, the safe utilization of pre-season passivated materials is prepared and applied as follows: 1.5-3 kg of dried Artemisia argyi leaves are added to 15-30 kg of water and extracted at 75℃ for 1 hour. After filtration through an 80-mesh filter cloth, the volume is adjusted to 15-25 kg to obtain a post-harvest Artemisia argyi hot water extract. 150-220 kg of commercial organic fertilizer, 10-20 kg of polyferric sulfate, 8-15 kg of potassium humate, 10-20 kg of oyster shell powder, 15-25 kg of post-harvest Artemisia argyi hot water extract, and 120-180 kg of water are mixed for 30 minutes and piled at 25℃ for 24-48 hours. The resulting material is then evenly spread on the surface of the treatment unit and rotary tilled into the 0-15 cm tillage layer. After rotary tillage, 250-350 kg of water is applied to maintain the moisture content of the 0-20 cm tillage layer at 60%-70% of field capacity, and the layer is maintained for 10-20 days.

[0015] The beneficial effects of this invention are: This invention utilizes the synergistic modification of organic materials with hot water extract of Artemisia argyi and potassium humate to construct an adsorption interface rich in active functional groups on the surface of biochar and organic fertilizer. This enhances the complexation capacity for cadmium and the pre-fixation capacity for arsenic from the source, laying the material foundation for subsequent zoned regulation. Cadmium-activating material containing buffered citrate is applied through the inner strip, combined with the local pulse input of free citric acid during the rapid growth period of Artemisia argyi, forming a short-term, highly efficient cadmium activation window in the root zone, significantly improving the absorption of cadmium by Artemisia argyi and the enrichment of cadmium in the aboveground parts. Simultaneously, an arsenic migration-controlling material containing polyferric sulfate is set in the outer strip. Utilizing the iron-arsenic precipitation reaction and the pH buffering effect of oyster shell powder, a physical-chemical dual interception barrier for arsenic migration is constructed, effectively blocking the diffusion of activated arsenic into the deep soil and root zone.

[0016] This invention achieves synergistic activation-resistance control during the remediation season and passivation switching before the safe utilization season through time-series control. After the remediation season ends, a composite passivation material containing Artemisia argyi extract is applied to smoothly transform the soil environment from an "activated remediation state" to a "safe utilization state." This avoids the arsenic risk caused by simple activation and overcomes the inhibition of remediation efficiency by traditional passivation.

[0017] The results of the examples show that the present invention can improve the removal of available cadmium in the rhizosphere and cadmium in the aboveground parts of Artemisia argyi while maintaining the soil pH in the rhizosphere at 5.54-5.93. The cadmium removal amount from Artemisia argyi in Example 1 was 6.55 g / 667 m³. 2 Compared to Comparative Example 4, which eliminated two local pulses of free citric acid monohydrate during the rapid growth phase, the concentration was 2.96 g / 667 m. 2 The improvement was 121.3%. In Example 1, compared to Comparative Example 5 (which omitted polyferric sulfate), the available arsenic in the outer strip (0-20cm) at harvest decreased from 2.418 mg / kg to 0.982 mg / kg, a reduction of 59.4%, and the total arsenic in the edible portion of the Chinese cabbage decreased from 0.422 mg / kg to 0.148 mg / kg, a reduction of 64.9%. In Example 1, compared to Comparative Example 8 (which used full-layer mixed application), the cadmium in the edible portion of the Chinese cabbage decreased from 0.214 mg / kg to 0.118 mg / kg, a reduction of 44.9%. In Example 1, compared to Comparative Example 9 (which omitted post-harvest safe utilization pre-season passivation treatment), the cadmium in the edible portion of the Chinese cabbage decreased from 0.236 mg / kg to 0.118 mg / kg, and the total arsenic decreased from 0.305 mg / kg to 0.148 mg / kg, indicating the necessity of switching from the activated repair state to the passivated safe utilization state after harvest. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0019] Raw material sources: Dried Artemisia argyi leaves are harvested from unpolluted areas, with a moisture content not exceeding 13%, total cadmium not exceeding 0.3 mg / kg, and total arsenic not exceeding 2 mg / kg. Artemisia argyi harvested from this treatment unit or other heavy metal-contaminated areas must not be used as extraction raw materials. Corn straw biochar is sourced from the Biochar and Green Agriculture Research Center of the Institute of Agricultural Resources and Ecological Environment, Nanjing Agricultural University, or equivalent crop straw biochar. The pyrolysis temperature is 450-550℃, particle size is 1-2 mm, moisture content is not exceeding 10%, and the total cadmium content of the incoming batch is not exceeding 3 mg / kg, and the total arsenic content is not exceeding 15 mg / kg. Commercial organic fertilizer is powdered bio-organic fertilizer from Nantong Erkang Bio-organic Fertilizer Co., Ltd., in 40 kg / bag specifications, conforming to NY / T525-2021, with an organic matter content of not less than 30%, a total nutrient content of not less than 4%, and a moisture content not exceeding 30%. The pH value is 6.5, and the heavy metal limits of the batches entering the site comply with NY / T525-2021; the potassium humate used is agricultural powdered potassium humate from Shandong Huayuan Humic Acid Ecological Agriculture Technology Co., Ltd., with a dry basis content of humic acid not less than 60%, potassium oxide content not less than 8%, and moisture not more than 15%; the polyferric sulfate used is solid polyferric sulfate from Longbai Group Co., Ltd., with a total iron content not less than 19%, a basicity of 10.5%, a pH of 2.2 for a 10g / L aqueous solution, and total arsenic not more than 0.0002% and total lead not more than 0.0002%; the oyster shell powder used is biological calcium carbonate oyster shell powder or oyster shell powder of equivalent grade from Penglai Marine Biological Co., Ltd., which is passed through an 80-mesh sieve before use, with a calcium carbonate content not less than 90%, moisture not more than 5%, total cadmium not more than 2mg / kg, and total arsenic not more than 5mg / kg; the irrigation water used meets the requirements for farmland irrigation water quality.

[0020] Example 1: Implementation location and soil conditions: 667 m² of cadmium-arsenic contaminated farmland with a total cadmium concentration of 1.350 mg / kg, a total arsenic concentration of 65 mg / kg, and a pH of 6.2 in the 0-20 cm topsoil layer was selected. 2 As a treatment unit, no edible crops are planted during the remediation season; only Artemisia argyi is planted for cadmium activation and absorption, as well as for aboveground removal. During the safe utilization season, crops are planted after the Artemisia argyi harvest. The soil is tilled to a depth of 20 cm, and the raised beds are kept level after preparation. Drainage ditches are installed to prevent continuous waterlogging during the activation period.

[0021] Step 1: 667m 2Soil samples from the 0-20cm topsoil layer were collected in the treatment unit using the five-point mixing method to test total cadmium, total arsenic, available cadmium, available arsenic, and soil pH. The treatment unit was then tilled to a depth of 20cm, soil clods larger than 3cm in diameter were broken up, and surface weeds and crop residues from the previous season were removed. Artemisia argyi planting strips were set along the length of the plot, with a center-to-center spacing of 50cm. Drainage ditches 20cm to 30cm deep were set up around the treatment unit to ensure that the surface water in the field during the activation period did not remain continuously for more than 24 hours.

[0022] Step 2: Add 34 kg of dried Artemisia argyi leaves to 340 kg of clean water and extract at 75°C for 2 hours. Stir once every 20 minutes for 5 minutes during extraction. After extraction, filter with an 80-mesh filter cloth. Rinse the filter residue with 34 kg of clean water and combine the filtrates. Concentrate the combined filtrate to 220 kg at 70°C, or add clean water to 220 kg if the combined filtrate is less than 220 kg, to obtain 220 kg of Artemisia argyi hot water extract for modifying the outer layer of organic materials. The Artemisia argyi hot water extract is used in Step 3 within 24 hours after preparation.

[0023] Step 3: Mix 120kg of corn stalk charcoal, 300kg of commercial organic fertilizer and 30kg of potassium humate for 20 minutes, then add 220kg of Artemisia argyi hot water extract for modifying the outer layer of organic materials and 80kg of water. Continue mixing for 30 minutes and then pile for 48 hours. The pile temperature is controlled at 25℃. During the pile period, turn the mixture once every 24 hours to obtain Artemisia argyi extract-modified organic materials.

[0024] Step 4: Take 450 kg of Artemisia argyi extract-modified organic material, add 8 kg of citric acid monohydrate, 8 kg of oyster shell powder and 80 kg of water, mix for 30 min and then pile at 20℃ to 35℃ for 24 h to obtain inner cadmium-activated material; make inner strips 25 cm wide and 12 cm deep along the intended planting row of Artemisia argyi, distribute all the inner cadmium-activated material equally according to the total length of the strips and apply it into the inner strips, and cover with 3 cm of soil.

[0025] Step 5: Take 300 kg of Artemisia argyi extract-modified organic material, add 25 kg of polyferric sulfate, 25 kg of oyster shell powder and 100 kg of water, mix for 30 min and then pile at 25℃ for 72 h. During the pile period, turn it over once every 24 h. The piled material should not be sealed to obtain the outer arsenic migration control material. On both sides of each inner strip, open outer strips with a width of 10 cm and a depth of 8 cm to 15 cm. The inner edge of the outer strip is 8 cm to 12 cm away from the edge of the inner strip. Distribute all the outer arsenic migration control material equally according to the total length of the outer strip and apply it into the outer strip, and cover it with soil.

[0026] Step Six: Transplant 90kg of Artemisia seedlings above the inner strip, with a plant spacing of 30cm, a row spacing of 50cm, and a transplanting depth of 8cm. Apply 500kg of clean water after transplanting. Within 15 days after transplanting, control the moisture content of the 0-20cm topsoil layer to 60% to 70% of field capacity. From 15 days after transplanting until harvest, control the moisture content of the 0-20cm topsoil layer to 55% to 70% of field capacity. The topsoil moisture content is measured using a soil moisture meter.

[0027] Step 7: 45 days after transplanting, add 2 kg of dried mugwort leaves to 20 kg of water and extract at 75℃ for 1 hour. Filter through an 80-mesh filter and bring the volume to 10 kg to obtain the first pre-use hot water extract of mugwort. Mix 3 kg of citric acid monohydrate, 10 kg of the first pre-use hot water extract of mugwort, and 100 kg of water to obtain the first root zone activation solution, and apply it to the soil surface only within a 10 cm radius of the base of the mugwort stem. 75 days after transplanting, prepare 10 kg of the second pre-use hot water extract of mugwort using the same method with 2 kg of dried mugwort leaves. Take the liquid, then mix 3 kg of citric acid monohydrate, 10 kg of the second-use Artemisia argyi hot water extract, and 100 kg of clean water to obtain the second root zone activation solution, and apply it to the same location. Before each application, measure the soil pH of the base of the Artemisia argyi stem (0-10 cm). If the pH is below 5, postpone the application until the pH recovers to above 5. Within 7 days after each application, control the moisture content of the 0-20 cm topsoil layer to 60% to 70% of field capacity. If the weather forecast predicts rainfall of more than 20 mm 24 hours before application, postpone the application until 48 hours after the rainfall ends.

[0028] Step 8: 120 days after transplanting, harvest the top part of the mugwort at 5cm from the ground surface. At the same time, collect the scattered leaves and stem residues on the field surface and remove them from the treatment unit. The harvested top part of the mugwort must not be returned to the farmland as medicinal material, feed, fuel ash fertilizer or organic fertilizer. It should be dried, compressed and temporarily stored or handed over to a qualified unit for treatment in accordance with the requirements for the management of plant residues contaminated with heavy metals. After harvesting, control the moisture content of the 0-20cm topsoil layer to 55% to 65% of field capacity and let it stand for 15 days.

[0029] Step 9: After standing for 15 days, add 2 kg of dried Artemisia argyi leaves to 20 kg of clean water and extract at 75℃ for 1 hour. After filtering through an 80-mesh filter cloth, bring the volume to 20 kg to obtain a hot water extract of Artemisia argyi for immediate use after harvest. Mix 180 kg of commercial organic fertilizer, 15 kg of polyferric sulfate, 10 kg of potassium humate, 15 kg of oyster shell powder, 20 kg of hot water extract of Artemisia argyi for immediate use after harvest, and 150 kg of clean water for 30 minutes. Pile the mixture at 25℃ for 24 hours. Then, evenly spread the material on the surface of the treatment unit and rotary tillage it into the 0-15 cm tillage layer. After rotary tillage, apply 300 kg of clean water to maintain the moisture content of the 0-20 cm tillage layer at 60% to 70% of field capacity and maintain it for 14 days.

[0030] Example 2: Implementation location and soil conditions: 667 m² of cadmium-arsenic contaminated farmland with a total cadmium concentration of 0.980 mg / kg, a total arsenic concentration of 48 mg / kg, and a pH of 5.8 in the 0-20 cm topsoil layer was selected. 2 As a treatment unit, no edible crops are planted during the remediation season; only Artemisia argyi is planted for cadmium activation and absorption, as well as for aboveground removal. During the safe utilization season, crops are planted after the Artemisia argyi harvest. The soil is tilled to a depth of 20 cm, and the raised beds are kept level after preparation. Drainage ditches are installed to prevent continuous waterlogging during the activation period.

[0031] Step 1: 667m 2 Soil samples from the 0-20cm topsoil layer were collected in the treatment unit using the five-point mixing method to test total cadmium, total arsenic, available cadmium, available arsenic, and soil pH. The treatment unit was then tilled to a depth of 20cm, soil clods larger than 3cm in diameter were broken up, and surface weeds and crop residues from the previous season were removed. Artemisia argyi planting strips were set along the length of the plot, with a center-to-center spacing of 50cm. Drainage ditches 20cm to 30cm deep were set up around the treatment unit to ensure that the surface water in the field during the activation period did not remain continuously for more than 24 hours.

[0032] Step 2: Add 30kg of dried Artemisia argyi leaves to 300kg of clean water and extract at 75℃ for 2 hours. Stir once every 20 minutes for 5 minutes during extraction. After extraction, filter with an 80-mesh filter cloth. Rinse the filter residue with 30kg of clean water and combine the filtrates. Concentrate the combined filtrate to 200kg at 70℃, or add clean water to 200kg if the combined filtrate is less than 200kg, to obtain 200kg of Artemisia argyi hot water extract for modifying the outer layer of organic materials. The Artemisia argyi hot water extract is used in Step 3 within 24 hours after preparation.

[0033] Step 3: Mix 105kg of corn stalk charcoal, 270kg of commercial organic fertilizer and 25kg of potassium humate for 20 minutes, then add 200kg of Artemisia argyi hot water extract for modifying the outer layer of organic materials and 90kg of water. Continue mixing for 30 minutes and then pile for 48 hours. The pile temperature is controlled at 25℃. During the pile period, turn the mixture once every 24 hours to obtain Artemisia argyi extract-modified organic materials.

[0034] Step 4: Take 400 kg of Artemisia argyi extract-modified organic material, add 5 kg of citric acid monohydrate, 10 kg of oyster shell powder and 70 kg of water, mix for 30 min and then pile at 20℃ to 35℃ for 24 h to obtain inner cadmium-activated material; make inner strips 22 cm wide and 10 cm deep along the intended planting row of Artemisia argyi, distribute all the inner cadmium-activated material equally according to the total length of the strips and apply it into the inner strips, and cover with 2 cm of soil.

[0035] Step 5: Take 290 kg of Artemisia argyi extract-modified organic material, add 20 kg of polyferric sulfate, 20 kg of oyster shell powder and 80 kg of water, mix for 30 min and then pile at 25℃ for 48 h. During the pile period, turn it over once every 24 h. The piled material should not be sealed to obtain the outer arsenic migration control material. On both sides of each inner strip, open outer strips with a width of 8 cm and a depth of 8 cm to 12 cm. The inner edge of the outer strip is 8 cm away from the edge of the inner strip. Distribute all the outer arsenic migration control material equally according to the total length of the outer strip and apply it into the outer strip, and cover it with soil.

[0036] Step Six: Transplant 85kg of Artemisia seedlings above the inner strip, with a plant spacing of 25cm, a row spacing of 50cm, and a transplanting depth of 6cm. Apply 400kg of clean water after transplanting. Within 15 days after transplanting, control the moisture content of the 0-20cm topsoil layer to 60% to 70% of field capacity. From 15 days after transplanting until harvest, control the moisture content of the 0-20cm topsoil layer to 55% to 70% of field capacity. The topsoil moisture content is measured using a soil moisture meter.

[0037] Step 7: 40 days after transplanting, add 1.6 kg of dried mugwort leaves to 16 kg of water and extract at 75℃ for 1 hour. Filter through an 80-mesh filter and bring the volume to 8 kg to obtain the first pre-use hot water extract of mugwort. Mix 2 kg of citric acid monohydrate, 8 kg of the first pre-use hot water extract of mugwort, and 80 kg of water to obtain the first root zone activation solution, and apply it to the soil surface only along an 8 cm radius around the base of the mugwort stem. 70 days after transplanting, prepare 8 kg of the second pre-use hot water extract of mugwort using the same method with 1.6 kg of dried mugwort leaves. The extract is then mixed with 2 kg of citric acid monohydrate, 8 kg of the second-use Artemisia argyi hot water extract, and 80 kg of water to obtain the second root zone activation solution. This solution is then applied to the same location. Before each application, the soil pH of the base of the Artemisia argyi stem (0-10 cm) is measured. If the pH is below 5, the application is postponed until the pH recovers to above 5. Within 7 days after each application, the moisture content of the 0-20 cm topsoil layer is controlled to 60% to 70% of field capacity. If the weather forecast predicts rainfall greater than 20 mm 24 hours before application, the application is postponed until 48 hours after the rainfall ends.

[0038] Step 8: 110 days after transplanting, harvest the top part of the mugwort at 5cm from the ground surface. At the same time, collect the scattered leaves and stem residues on the field surface and remove them from the treatment unit. The harvested top part of the mugwort must not be returned to the farmland as medicinal material, feed, fuel ash fertilizer or organic fertilizer. It should be dried, compressed and temporarily stored or handed over to a qualified unit for treatment in accordance with the requirements for the management of plant residues contaminated with heavy metals. After harvesting, control the moisture content of the 0-20cm topsoil layer to 55% to 65% of field capacity and let it stand for 10 days.

[0039] Step 9: After standing for 10 days, add 1.5 kg of dried Artemisia argyi leaves to 15 kg of clean water and extract at 75℃ for 1 hour. After filtering through an 80-mesh filter cloth, bring the volume to 15 kg to obtain a hot water extract of Artemisia argyi for immediate use after harvest. Mix 150 kg of commercial organic fertilizer, 10 kg of polyferric sulfate, 8 kg of potassium humate, 10 kg of oyster shell powder, 15 kg of hot water extract of Artemisia argyi for immediate use after harvest, and 120 kg of clean water for 30 minutes. Pile the mixture at 25℃ for 24 hours. Then, evenly spread the material on the surface of the treatment unit and rotary tillage it into the 0-15 cm tillage layer. After rotary tillage, apply 250 kg of clean water to maintain the moisture content of the 0-20 cm tillage layer at 60% to 70% of field capacity and maintain it for 10 days.

[0040] Example 3: Implementation location and soil conditions: 667 m² of cadmium-arsenic contaminated farmland with a total cadmium concentration of 1.780 mg / kg, a total arsenic concentration of 78 mg / kg, and a pH of 6.4 in the 0-20 cm topsoil layer was selected. 2 As a treatment unit, no edible crops are planted during the remediation season; only Artemisia argyi is planted for cadmium activation and absorption, as well as for aboveground removal. During the safe utilization season, crops are planted after the Artemisia argyi harvest. The soil is tilled to a depth of 20 cm, and the raised beds are kept level after preparation. Drainage ditches are installed to prevent continuous waterlogging during the activation period.

[0041] Step 1: 667m 2 Soil samples from the 0-20cm topsoil layer were collected in the treatment unit using the five-point mixing method to test total cadmium, total arsenic, available cadmium, available arsenic, and soil pH. The treatment unit was then tilled to a depth of 20cm, soil clods larger than 3cm in diameter were broken up, and surface weeds and crop residues from the previous season were removed. Artemisia argyi planting strips were set along the length of the plot, with a center-to-center spacing of 55cm. Drainage ditches 20cm to 30cm deep were set up around the treatment unit to ensure that the surface water in the field during the activation period did not remain continuously for more than 24 hours.

[0042] Step 2: Add 40kg of dried Artemisia argyi leaves to 400kg of clean water and extract at 75℃ for 2 hours. Stir once every 20 minutes for 5 minutes during extraction. After extraction, filter with an 80-mesh filter cloth. Rinse the filter residue with 40kg of clean water and combine the filtrates. Concentrate the combined filtrate to 230kg at 70℃, or add clean water to 230kg if the combined filtrate is less than 230kg, to obtain 230kg of Artemisia argyi hot water extract for modifying the outer layer of organic materials. The Artemisia argyi hot water extract is used in Step 3 within 24 hours after preparation.

[0043] Step 3: Mix 150kg of corn stalk charcoal, 360kg of commercial organic fertilizer and 40kg of potassium humate for 30 minutes, then add 230kg of Artemisia argyi hot water extract for modifying the outer layer of organic materials and 60kg of water. Continue mixing for 30 minutes and then pile for 60 hours. The pile temperature is controlled at 25℃. During the pile period, turn the mixture once every 24 hours to obtain Artemisia argyi extract-modified organic materials.

[0044] Step 4: Take 500 kg of Artemisia argyi extract-modified organic material, add 12 kg of citric acid monohydrate, 12 kg of oyster shell powder and 100 kg of water, mix for 30 min and then pile at 20℃ to 35℃ for 24 h to obtain inner cadmium-activated material; make inner strips 30 cm wide and 15 cm deep along the intended planting row of Artemisia argyi, distribute all the inner cadmium-activated material equally according to the total length of the strips and apply it into the inner strips, and cover with 5 cm of soil.

[0045] Step 5: Take 340 kg of Artemisia argyi extract-modified organic material, add 35 kg of polyferric sulfate, 30 kg of oyster shell powder and 120 kg of water, mix for 30 min and then pile at 25℃ for 96 h. During the pile period, turn it over once every 24 h. The piled material should not be sealed to obtain the outer arsenic migration control material. On both sides of each inner strip, open outer strips with a width of 12 cm and a depth of 12 cm to 15 cm. The inner edge of the outer strip is 12 cm away from the edge of the inner strip. Distribute all the outer arsenic migration control material equally according to the total length of the outer strip and apply it into the outer strip, and cover it with soil.

[0046] Step Six: Transplant 100kg of Artemisia seedlings above the inner strip, with a plant spacing of 35cm, a row spacing of 55cm, and a transplanting depth of 10cm. Apply 600kg of clean water after transplanting. Within 15 days after transplanting, control the moisture content of the 0-20cm topsoil layer to 60% to 70% of field capacity. From 15 days after transplanting until harvest, control the moisture content of the 0-20cm topsoil layer to 55% to 70% of field capacity. The topsoil moisture content is measured using a soil moisture meter.

[0047] Step 7: 50 days after transplanting, add 2.4 kg of dried mugwort leaves to 24 kg of water and extract at 75℃ for 1 hour. Filter through an 80-mesh filter and bring the volume to 12 kg to obtain the first pre-use hot water extract of mugwort. Mix 4 kg of citric acid monohydrate, 12 kg of the first pre-use hot water extract of mugwort, and 120 kg of water to obtain the first root zone activation solution, and apply it to the soil surface only along a 12 cm radius around the base of the mugwort stem. 80 days after transplanting, use the same method to prepare 12 kg of the second pre-use hot water extract of mugwort. The aqueous extract is then mixed with 4 kg of citric acid monohydrate, 12 kg of the second-use Artemisia argyi hot water extract, and 120 kg of water to obtain the second root zone activation solution. This solution is then applied to the same location. Before each application, the soil pH of the base of the Artemisia argyi stem (0-10 cm) is measured. If the pH is below 5, the application is postponed until the pH recovers to above 5. Within 7 days after each application, the moisture content of the 0-20 cm topsoil layer is controlled to 60% to 70% of field capacity. If the weather forecast predicts rainfall greater than 20 mm 24 hours before application, the application is postponed until 48 hours after the rainfall ends.

[0048] Step 8: 130 days after transplanting, harvest the top part of the mugwort at 5cm from the ground surface. At the same time, collect the scattered leaves and stem residues on the field surface and remove them from the treatment unit. The harvested top part of the mugwort must not be returned to the farmland as medicinal material, feed, fuel ash fertilizer or organic fertilizer. It should be dried, compressed and temporarily stored or handed over to a qualified unit for treatment in accordance with the requirements for the management of plant residues contaminated with heavy metals. After harvesting, control the moisture content of the 0-20cm topsoil layer to 55% to 65% of field capacity and let it stand for 20 days.

[0049] Step 9: After standing for 20 days, add 3 kg of dried Artemisia argyi leaves to 30 kg of clean water and extract at 75℃ for 1 hour. After filtering through an 80-mesh filter cloth, bring the volume to 25 kg to obtain a hot water extract of Artemisia argyi for immediate use after harvest. Mix 220 kg of commercial organic fertilizer, 20 kg of polyferric sulfate, 15 kg of potassium humate, 20 kg of oyster shell powder, 25 kg of hot water extract of Artemisia argyi for immediate use after harvest, and 180 kg of clean water for 30 minutes. Pile the mixture at 25℃ for 48 hours. Then, evenly spread the material on the surface of the treatment unit and rotary tillage it into the 0-15 cm tillage layer. After rotary tillage, apply 350 kg of clean water to maintain the moisture content of the 0-20 cm tillage layer at 60% to 70% of field capacity and maintain it for 20 days.

[0050] Example 4: Implementation location and soil conditions: 667 m² of cadmium-arsenic contaminated farmland with a total cadmium concentration of 1.240 mg / kg, a total arsenic concentration of 66 mg / kg, and a pH of 5.4 in the 0-20 cm topsoil layer was selected. 2As a treatment unit, no edible crops are planted during the remediation season; only Artemisia argyi is planted for cadmium activation and absorption, as well as for aboveground removal. During the safe utilization season, crops are planted after the Artemisia argyi harvest. The soil is tilled to a depth of 20 cm, and the raised beds are kept level after preparation. Drainage ditches are installed to prevent continuous waterlogging during the activation period.

[0051] Step 1: 667m 2 Soil samples from the 0-20cm topsoil layer were collected in the treatment unit using the five-point mixing method to test total cadmium, total arsenic, available cadmium, available arsenic, and soil pH. The treatment unit was then tilled to a depth of 20cm, soil clods larger than 3cm in diameter were broken up, and surface weeds and crop residues from the previous season were removed. Artemisia argyi planting strips were set along the length of the plot, with a center-to-center spacing of 50cm. Drainage ditches 20cm to 30cm deep were set up around the treatment unit to ensure that the surface water in the field during the activation period did not remain continuously for more than 24 hours.

[0052] Step 2: Add 36 kg of dried Artemisia argyi leaves to 360 kg of clean water and extract at 75°C for 2 hours. Stir once every 20 minutes for 5 minutes during extraction. After extraction, filter with an 80-mesh filter cloth. Rinse the filter residue with 36 kg of clean water and combine the filtrates. Concentrate the combined filtrate to 210 kg at 70°C, or add clean water to 210 kg if the combined filtrate is less than 210 kg, to obtain 210 kg of Artemisia argyi hot water extract for modifying the outer layer of organic materials. The Artemisia argyi hot water extract is used in Step 3 within 24 hours after preparation.

[0053] Step 3: Mix 130kg of corn stalk charcoal, 320kg of commercial organic fertilizer and 35kg of potassium humate for 20 minutes, then add 210kg of Artemisia argyi hot water extract for modifying the outer layer of organic materials and 55kg of water. Continue mixing for 30 minutes and then pile for 48 hours. The pile temperature is controlled at 25℃. During the pile period, turn the mixture once every 24 hours to obtain Artemisia argyi extract-modified organic materials.

[0054] Step 4: Take 450 kg of Artemisia argyi extract-modified organic material, add 7 kg of citric acid monohydrate, 14 kg of oyster shell powder and 80 kg of water, mix for 30 min and then pile at 20℃ to 35℃ for 24 h to obtain inner cadmium-activated material; make inner strips 25 cm wide and 12 cm deep along the intended planting row of Artemisia argyi, distribute all the inner cadmium-activated material equally according to the total length of the strips and apply it into the inner strips, and cover with 3 cm of soil.

[0055] Step 5: Take 300 kg of Artemisia argyi extract-modified organic material, add 28 kg of polyferric sulfate, 35 kg of oyster shell powder and 100 kg of water, mix for 30 min and then pile at 25℃ for 72 h. During the pile period, turn it over once every 24 h. The piled material should not be sealed to obtain the outer arsenic migration control material. On both sides of each inner strip, open outer strips with a width of 10 cm and a depth of 10 cm to 15 cm. The inner edge of the outer strip is 10 cm away from the edge of the inner strip. Distribute all the outer arsenic migration control material equally according to the total length of the outer strip and apply it into the outer strip, and cover it with soil.

[0056] Step Six: Transplant 90kg of Artemisia seedlings above the inner strip, with a plant spacing of 30cm, a row spacing of 50cm, and a transplanting depth of 8cm. Apply 500kg of clean water after transplanting. Within 15 days after transplanting, control the moisture content of the 0-20cm topsoil layer to 60% to 70% of field capacity. From 15 days after transplanting until harvest, control the moisture content of the 0-20cm topsoil layer to 55% to 70% of field capacity. The topsoil moisture content is measured using a soil moisture meter.

[0057] Step 7: 45 days after transplanting, add 2 kg of dried mugwort leaves to 20 kg of water and extract at 75℃ for 1 hour. Filter through an 80-mesh filter and bring the volume to 10 kg to obtain the first pre-use hot water extract of mugwort. Mix 2.5 kg of citric acid monohydrate, 10 kg of the first pre-use hot water extract of mugwort, and 100 kg of water to obtain the first root zone activation solution, and apply it to the soil surface only within a 10 cm radius of the base of the mugwort stem. 75 days after transplanting, prepare 10 kg of the second pre-use hot water extract of mugwort using the same method with 2 kg of dried mugwort leaves. Take the liquid, then mix 2.5 kg of citric acid monohydrate, 10 kg of the second-use Artemisia argyi hot water extract, and 100 kg of clean water to obtain the second root zone activation solution, and apply it to the same location. Before each application, measure the soil pH of the base of the Artemisia argyi stem (0-10 cm). If the pH is below 5, postpone the application until the pH recovers to above 5. Within 7 days after each application, control the moisture content of the 0-20 cm topsoil layer to 60% to 70% of field capacity. If the weather forecast predicts rainfall greater than 20 mm 24 hours before application, postpone the application until 48 hours after the rainfall ends.

[0058] Step 8: 120 days after transplanting, harvest the top part of the mugwort at 5cm from the ground surface. At the same time, collect the scattered leaves and stem residues on the field surface and remove them from the treatment unit. The harvested top part of the mugwort must not be returned to the farmland as medicinal material, feed, fuel ash fertilizer or organic fertilizer. It should be dried, compressed and temporarily stored or handed over to a qualified unit for treatment in accordance with the requirements for the management of plant residues contaminated with heavy metals. After harvesting, control the moisture content of the 0-20cm topsoil layer to 55% to 65% of field capacity and let it stand for 15 days.

[0059] Step 9: After standing for 15 days, add 2 kg of dried Artemisia argyi leaves to 20 kg of clean water and extract at 75℃ for 1 hour. After filtering through an 80-mesh filter cloth, bring the volume to 20 kg to obtain a hot water extract of Artemisia argyi for immediate use after harvest. Mix 190 kg of commercial organic fertilizer, 18 kg of polyferric sulfate, 12 kg of potassium humate, 20 kg of oyster shell powder, 20 kg of hot water extract of Artemisia argyi for immediate use after harvest, and 150 kg of clean water for 30 minutes. Pile the mixture at 25℃ for 24 hours. Then, evenly spread the material on the surface of the treatment unit and rotary tillage it into the 0-15 cm tillage layer. After rotary tillage, apply 300 kg of clean water to maintain the moisture content of the 0-20 cm tillage layer at 60% to 70% of field capacity and maintain it for 14 days.

[0060] Example 5: Implementation location and soil conditions: 667 m² of cadmium-arsenic contaminated farmland with a total cadmium concentration of 1.120 mg / kg, a total arsenic concentration of 82 mg / kg, and a pH of 6.8 in the 0-20 cm topsoil layer was selected. 2 As a treatment unit, no edible crops are planted during the remediation season; only Artemisia argyi is planted for cadmium activation and absorption, as well as for aboveground removal. During the safe utilization season, crops are planted after the Artemisia argyi harvest. The soil is tilled to a depth of 20 cm, and the raised beds are kept level after preparation. Drainage ditches are installed to prevent continuous waterlogging during the activation period.

[0061] Step 1: 667m 2 Soil samples from the 0-20cm topsoil layer were collected in the treatment unit using the five-point mixing method to test total cadmium, total arsenic, available cadmium, available arsenic, and soil pH. The treatment unit was then tilled to a depth of 20cm, soil clods larger than 3cm in diameter were broken up, and surface weeds and crop residues from the previous season were removed. Artemisia argyi planting strips were set along the length of the plot, with a center-to-center spacing of 50cm. Drainage ditches 20cm to 30cm deep were set up around the treatment unit to ensure that the surface water in the field during the activation period did not remain continuously for more than 24 hours.

[0062] Step 2: Add 38 kg of dried Artemisia argyi leaves to 380 kg of water and extract at 75°C for 2 hours. Stir once every 20 minutes for 5 minutes during extraction. After extraction, filter with an 80-mesh filter cloth. Rinse the filter residue with 38 kg of water and combine the filtrates. Concentrate the combined filtrate to 240 kg at 70°C, or add water to bring the combined filtrate to 240 kg if it is less than 240 kg, to obtain 240 kg of Artemisia argyi hot water extract for modifying the outer layer of organic materials. The Artemisia argyi hot water extract is used in Step 3 within 24 hours after preparation.

[0063] Step 3: Mix 140kg of corn stalk charcoal, 340kg of commercial organic fertilizer and 35kg of potassium humate for 20 minutes, then add 240kg of Artemisia argyi hot water extract for modifying the outer layer of organic materials and 45kg of water. Continue mixing for 30 minutes and then pile for 48 hours. The pile temperature is controlled at 25℃. During the pile period, turn the mixture once every 24 hours to obtain Artemisia argyi extract-modified organic materials.

[0064] Step 4: Take 470 kg of Artemisia argyi extract-modified organic material, add 6 kg of citric acid monohydrate, 10 kg of oyster shell powder and 90 kg of water, mix for 30 min and then pile at 20℃ to 35℃ for 24 h to obtain inner cadmium-activated material; make inner strips 25 cm wide and 12 cm deep along the intended planting row of Artemisia argyi, distribute all the inner cadmium-activated material equally according to the total length of the strips and apply it into the inner strips, and cover with 3 cm of soil.

[0065] Step 5: Take 330 kg of Artemisia argyi extract-modified organic material, add 35 kg of polyferric sulfate, 25 kg of oyster shell powder and 110 kg of water, mix for 30 min and then pile at 25℃ for 72 h. During the pile period, turn it over once every 24 h. The piled material should not be sealed to obtain the outer arsenic migration control material. On both sides of each inner strip, open outer strips with a width of 10 cm and a depth of 8 cm to 15 cm. The inner edge of the outer strip is 9 cm away from the edge of the inner strip. Distribute all the outer arsenic migration control material equally according to the total length of the outer strip and apply it into the outer strip, and cover it with soil.

[0066] Step Six: Transplant 90kg of Artemisia seedlings above the inner strip, with a plant spacing of 30cm, a row spacing of 50cm, and a transplanting depth of 8cm. Apply 500kg of clean water after transplanting. Within 15 days after transplanting, control the moisture content of the 0-20cm topsoil layer to 60% to 70% of field capacity. From 15 days after transplanting until harvest, control the moisture content of the 0-20cm topsoil layer to 55% to 70% of field capacity. The topsoil moisture content is measured using a soil moisture meter.

[0067] Step 7: 45 days after transplanting, add 2 kg of dried mugwort leaves to 20 kg of water and extract at 75℃ for 1 hour. Filter through an 80-mesh filter and bring the volume to 10 kg to obtain the first pre-use hot water extract of mugwort. Mix 2 kg of citric acid monohydrate, 10 kg of the first pre-use hot water extract of mugwort, and 100 kg of water to obtain the first root zone activation solution, and apply it to the soil surface only within a 10 cm radius of the base of the mugwort stem. 75 days after transplanting, prepare 10 kg of the second pre-use hot water extract of mugwort using the same method with 2 kg of dried mugwort leaves. Take the liquid, then mix 2 kg of citric acid monohydrate, 10 kg of the second-use Artemisia argyi hot water extract, and 100 kg of clean water to obtain the second root zone activation solution, and apply it to the same location. Before each application, measure the soil pH of the base of the Artemisia argyi stem (0-10 cm). If the pH is below 5, postpone the application until the pH recovers to above 5. Within 7 days after each application, control the moisture content of the 0-20 cm topsoil layer to 60% to 70% of field capacity. If the weather forecast predicts rainfall of more than 20 mm 24 hours before application, postpone the application until 48 hours after the rainfall ends.

[0068] Step 8: 120 days after transplanting, harvest the top part of the mugwort at 5cm from the ground surface. At the same time, collect the scattered leaves and stem residues on the field surface and remove them from the treatment unit. The harvested top part of the mugwort must not be returned to the farmland as medicinal material, feed, fuel ash fertilizer or organic fertilizer. It should be dried, compressed and temporarily stored or handed over to a qualified unit for treatment in accordance with the requirements for the management of plant residues contaminated with heavy metals. After harvesting, control the moisture content of the 0-20cm topsoil layer to 55% to 65% of field capacity and let it stand for 15 days.

[0069] Step 9: After standing for 15 days, add 2.5 kg of dried Artemisia argyi leaves to 25 kg of clean water and extract at 75℃ for 1 hour. After filtering through an 80-mesh filter cloth, bring the volume to 25 kg to obtain a hot water extract of Artemisia argyi for immediate use after harvest. Mix 210 kg of commercial organic fertilizer, 20 kg of polyferric sulfate, 12 kg of potassium humate, 18 kg of oyster shell powder, 25 kg of hot water extract of Artemisia argyi for immediate use after harvest, and 160 kg of clean water for 30 minutes. Pile the mixture at 25℃ for 24 hours. Then, evenly spread the material on the surface of the treatment unit and rotary tillage it into the 0-15 cm topsoil layer. After rotary tillage, apply 300 kg of clean water to maintain the moisture content of the 0-20 cm topsoil layer at 60% to 70% of field capacity and maintain it for 14 days.

[0070] Comparative Example 1: The difference from Example 1 is as follows: Step 2 is omitted; in Step 3, 220 kg of Artemisia argyi hot water extract for modifying the outer layer of organic materials is not added, and 220 kg of Artemisia argyi hot water extract for modifying the outer layer of organic materials is replaced with an equal amount of water; in Step 7, the first and second batches of Artemisia argyi hot water extract are replaced with an equal amount of water; in Step 9, the post-harvest Artemisia argyi hot water extract is replaced with an equal amount of water, and the remaining conditions are the same as in Example 1.

[0071] Comparative Example 2: The difference from Example 1 is that: in step three, 30 kg of potassium humate is not added, and 30 kg of potassium humate is replaced with 30 kg of commercial organic fertilizer; in step nine, 10 kg of potassium humate is not added, and 10 kg of potassium humate is replaced with 10 kg of commercial organic fertilizer, and the other conditions are the same as in Example 1.

[0072] Comparative Example 3: The difference from Example 1 is that 8 kg of citric acid monohydrate is not added in step four, and 8 kg of citric acid monohydrate is replaced by 8 kg of Artemisia argyi extract-modified organic material. The other conditions are the same as in Example 1.

[0073] Comparative Example 4: The difference from Example 1 is that in step seven, the first root zone activation solution does not contain 3 kg of citric acid monohydrate, and the 3 kg of citric acid monohydrate is replaced with an equal amount of 3 kg of water; the second root zone activation solution does not contain 3 kg of citric acid monohydrate, and the 3 kg of citric acid monohydrate is replaced with an equal amount of 3 kg of water, and the other conditions are the same as in Example 1.

[0074] Comparative Example 5: The difference from Example 1 is that: in step five, 25 kg of polyferric sulfate is not added, and 25 kg of polyferric sulfate is replaced by an equal amount of 25 kg of Artemisia argyi extract-modified organic material; in step nine, 15 kg of polyferric sulfate is not added, and 15 kg of polyferric sulfate is replaced by an equal amount of 15 kg of commercial organic fertilizer, and the other conditions are the same as in Example 1.

[0075] Comparative Example 6: The difference from Example 1 is that in step five, the distance between the inner edge of the outer strip and the edge of the inner strip is changed from 8cm to 12cm to 0cm, while the other conditions are the same as in Example 1.

[0076] Comparative Example 7: The difference from Example 1 is that in step five, the distance between the inner edge of the outer strip and the edge of the inner strip is changed from 8cm to 12cm to 20cm, while the other conditions are the same as in Example 1.

[0077] Comparative Example 8: The difference from Example 1 is that the inner cadmium-activated material obtained in step four and the outer arsenic-controlled migration material obtained in step five are not applied to the inner and outer strips respectively, but are uniformly spread on the surface of the treatment unit after preparation and mixed into the 0-15cm tillage layer by rotary tillage. The other conditions are the same as in Example 1.

[0078] Comparative Example 9: The difference from Example 1 is that step nine is omitted, while the remaining conditions are the same as in Example 1.

[0079] Performance testing: A contiguous area of ​​cadmium-arsenic contaminated farmland was selected as the performance testing site. The total cadmium concentration in the 0-20cm topsoil layer was 1.320-1.390 mg / kg, the total arsenic concentration was 62-68 mg / kg, and the pH was 6.0-6.4. The testing site was divided into 14 treatments: Examples 1-5 and Comparative Examples 1-9. Each treatment had three replicate plots, and each plot had an area of ​​20m². 2 A 1.0m wide buffer zone and independent drainage ditch shall be set up between adjacent communities. The usage of solid materials, liquid materials, and clean water within each community shall be based on 20m³. 2 With 667m 2 The area ratio calculation is not based on the area ratio for the following parameters: inner strip width, inner strip depth, outer strip width, outer strip depth, distance from the inner edge of the outer strip to the edge of the inner strip, Artemisia plant spacing, Artemisia row spacing, transplanting depth, irrigation radius, harvesting height, soil sampling depth, and rotary tillage depth. Each treatment follows the corresponding embodiment or comparative example to complete the Artemisia remediation season treatment, Artemisia harvest, post-harvest settling, and pre-season passivation treatment for safe utilization. Comparative Example 9 does not apply post-harvest passivation material at the corresponding time in step nine of Example 1, but maintains the same soil moisture content and curing time. After the pre-season passivation curing for safe utilization is completed, Chinese cabbage is planted in each plot with a row spacing of 20cm and a plant spacing of 15cm. No additional soil remediation material containing heavy metal regulation is applied. Irrigation water complies with GB 5084-2021. Edible parts are harvested 35 days after planting for testing.

[0080] Soil pH and available cadmium in the root zone: Soil samples were collected from the 0-20cm root zone within a 10cm radius of the Artemisia argyi stem base in each plot on the 7th day after the first and second application of the root zone activation solution. Five samples were collected from each plot, mixed thoroughly, and after removing plant debris and stones, the soil was air-dried, ground, and sieved through a 2mm sieve. Soil pH was determined according to NY / T 1121.2-2006. 10.00g of sieved soil sample was weighed, 25.0mL of decarbonated water was added, stirred for 1 min, and allowed to stand for 30 min before being measured using a pH meter. Available cadmium in the soil was determined according to GB / T 23739-2009. Air-dried soil samples that had passed through a 2mm sieve were extracted, and the cadmium content of the extract was determined after filtration through a filter membrane. Soil pH and available cadmium in the root zone on the 7th day after the second application of the root zone activation solution were used as characterization indicators.

[0081] Dry weight, cadmium content, and cadmium removal of Artemisia argyi aboveground parts: At the corresponding harvest time in each example and comparative example, all aboveground parts of Artemisia argyi in each plot were harvested at 5 cm above the ground surface. Simultaneously, scattered leaves and residual stems were collected from the field surface, and the fresh weight of the aboveground parts of Artemisia argyi in each plot was recorded. A representative sample of 1.000 kg was taken from the mixed aboveground parts of Artemisia argyi in each plot, rinsed sequentially with tap water and deionized water, surface moisture was absorbed, and the sample was blanched at 105℃ for 30 min, then dried at 65℃ to constant weight. The dry weight was recorded, and the sample was pulverized and sieved through a 0.25 mm sieve. The cadmium content of the aboveground parts of Artemisia argyi was determined according to GB 5009.15-2023 or ICP-MS. The cadmium removal of the aboveground parts of Artemisia argyi was calculated using the following formula: The cadmium removal of the aboveground parts of Artemisia argyi equals the amount converted to 667 m³. 2 Multiply the dry matter content of the upper part of the Artemisia argyi by the cadmium content of the upper part of the Artemisia argyi, then divide by 1000, with the unit being g / 667m³. 2 .

[0082] Available arsenic in the outer strip and the soil layer below it: On the day of Artemisia argyi harvest, soil samples were collected from 0-20 cm along the length of the outer strip in each plot, and soil samples were also collected from 20-40 cm at the corresponding locations. Five samples were collected at each depth, mixed thoroughly, and after removing plant debris and stones, the samples were air-dried, ground, and sieved through a 2 mm sieve. Available arsenic in the soil was determined according to GB / T44741-2024 or ICP-MS. Available arsenic in the 0-20 cm outer strip and the 20-40 cm below the outer strip were used as indicators for arsenic migration control.

[0083] Cadmium and total arsenic content in the edible parts of Chinese cabbage for safe utilization: After harvesting from each treatment, Chinese cabbage was allowed to stand and undergo passivation treatment before the safe utilization season. The cabbage was then planted in the corresponding plots, and the edible parts were harvested 35 days after planting. Edge plants were removed during sampling. At least 1,000 kg of edible parts were randomly collected from each plot, rinsed sequentially with tap water and then with deionized water, dried, chopped, and homogenized. Cadmium content in the edible parts of Chinese cabbage was determined according to GB 5009.15-2023 or ICP-MS, and total arsenic content was determined according to GB 5009.11-2024 or ICP-MS. The limits for contaminants in food specified in GB 2762-2022 were used as the basis for safe utilization evaluation. Both cadmium and total arsenic content in the edible parts of Chinese cabbage were based on fresh weight.

[0084] Table 1 Performance Test Results

[0085] As shown in Table 1, the soil pH in the root zone of Examples 1-5 remained between 5.54 and 5.93 on day 7 after the second application of the root zone activation solution, without excessive acidification. This indicates that the local input of citric acid monohydrate, along with the buffering effect of oyster shell powder and organic materials, could maintain a suitable root zone environment. In Example 3, due to the relatively high dosages of Artemisia argyi hot water extract, potassium humate, corn straw charcoal, commercial organic fertilizer, citric acid monohydrate, and polyferric sulfate, the available cadmium in the root zone reached 0.635 mg / kg on day 7 after the second application of the root zone activation solution. The dry matter content, cadmium content, and cadmium removal of the Artemisia argyi aboveground parts reached 205.6 kg / 667 m². 2 31.85 mg / kg and 6.55 g / 667 mg 2 The results were significantly higher than those in Examples 1, 2, 4 and 5, indicating that under conditions of high pollution load or strong remediation demand, enhancing the organic material interface capacity and combining it with appropriate root zone activation is beneficial to improving the absorption of cadmium and the removal of cadmium by Artemisia argyi from the aboveground parts.

[0086] Compared with Example 1, after omitting the hot water extract of Artemisia argyi in Comparative Example 1 and potassium humate in Comparative Example 2, the amount of cadmium removed from the upper part of Artemisia argyi decreased to 3.37 g / 667 m³. 2 and 3.39g / 667m 2 The cadmium content in the edible parts of Chinese cabbage increased to 0.216 mg / kg and 0.204 mg / kg, respectively, indicating that the combined use of hot water extract of Artemisia argyi and potassium humate in the modification of the outer layer of organic materials helps to improve the buffering and passivation effect before the remediation season for cadmium absorption and safe utilization. In Comparative Example 3, citric acid monohydrate was removed from the inner cadmium-activating material. In Comparative Example 4, after removing two local pulses of free citric acid monohydrate during the rapid growth period, the available cadmium in the root zone decreased to 0.414 mg / kg and 0.366 mg / kg, respectively, and the cadmium removal amount from the upper part of Artemisia argyi decreased to 3.36 g / 667 m³.2 and 2.96g / 667m 2 This indicates that the buffering preconditioning of citric acid monohydrate and the local pulse input during the rapid growth period both contribute to the formation of a short-term cadmium activation window that can be absorbed and covered by Artemisia argyi.

[0087] In Comparative Example 5, after removing polyferric sulfate, the amount of cadmium removed from the upper part of Artemisia argyi was still 4.63 g / 667 m³. 2 However, at harvest time, the available arsenic in the outer strips (0-20cm and 20-40cm) increased to 2.418 mg / kg and 0.956 mg / kg, respectively, and the total arsenic content in the edible part of the Chinese cabbage increased to 0.422 mg / kg. This indicates that simply maintaining cadmium activation cannot simultaneously control arsenic migration and ensure the safety of subsequent crops.

[0088] In Comparative Example 6, after the outer strip was abutted against the inner strip, the amount of available cadmium in the root zone and the amount of cadmium removed from the upper part of Artemisia argyi decreased to 0.397 mg / kg and 3.08 g / 667 m³, respectively. 2 In Comparative Example 7, after increasing the distance between the outer strips to 20 cm, the amount of cadmium removed from the upper part of Artemisia argyi remained at 4.74 g / 667 m³. 2 However, the available arsenic in the outer bands at 0-20cm and 20-40cm increased to 1.552 mg / kg and 0.762 mg / kg, respectively, indicating that if the outer bands are too close, they will weaken the activation of cadmium in the inner root region, while if they are too far apart, they will not be able to intercept the arsenic migration pathway.

[0089] In Comparative Example 8, after the inner cadmium-activating material and the outer arsenic-controlling material were mixed and applied throughout the entire layer, the cadmium removal amount in the upper part of Artemisia argyi decreased to 2.91 g / 667 m². 2 The cadmium content and total arsenic content of the edible part of Chinese cabbage were 0.214 mg / kg and 0.282 mg / kg, respectively, indicating that the application of inner and outer strips in a zoned manner cannot be replaced by ordinary whole-layer mixed application.

[0090] In Comparative Example 9, after the pre-harvest passivation treatment for safe utilization was cancelled, the relevant indicators of Artemisia argyi during the restoration season were similar to those in Example 1. However, the cadmium content and total arsenic content of the edible part of the Chinese cabbage increased to 0.236 mg / kg and 0.305 mg / kg, respectively, indicating that it is necessary to switch Artemisia argyi from the activated restoration state to the passivated safe utilization state after harvest.

[0091] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention is limited to these examples; within the framework of the invention, the technical features of the above embodiments or different embodiments can also be combined, and there are many other variations of the different aspects of the invention as described above, which are not provided in detail for the sake of brevity.

Claims

1. A method for remediating cadmium and arsenic compound pollution in arable land based on Artemisia argyi extraction and organic material regulation, characterized in that, Includes the following steps: S1. Taking cadmium-arsenic combined contaminated farmland as the treatment target, Artemisia argyi planting rows are set up in the cadmium-arsenic combined contaminated farmland during the remediation season. S2. A hot water extract of Artemisia argyi for modifying the outer layer of organic materials is obtained by hot water extraction of dried Artemisia argyi and water. Crop straw biochar, commercial organic fertilizer, potassium humate, the hot water extract of Artemisia argyi for modifying the outer layer of organic materials and water are mixed and piled up to obtain Artemisia argyi extract-modified organic materials. S3. The directional modified organic material of Artemisia argyi extract is divided into two parts. One part is mixed with citric acid monohydrate, oyster shell powder and water and piled up to obtain the inner cadmium-activating material. The other part is mixed with polyferric sulfate, oyster shell powder and water and piled up to obtain the outer arsenic migration control material. S4. Set an inner strip along the Artemisia argyi planting row, and apply the inner cadmium activating material into the inner strip; set outer strips on both sides of the inner strip, and apply the outer arsenic migration control material into the outer strip, with the inner edge of the outer strip being 8-12cm away from the edge of the inner strip. S5. Transplant the mugwort seedlings above the inner strip. 40-50 days and 70-80 days after transplanting, extract the mugwort hot water extract from dried mugwort leaves and water respectively to obtain a ready-to-use mugwort hot water extract. Mix the ready-to-use mugwort hot water extract, citric acid monohydrate and water to form a root zone activation solution. Apply the root zone activation solution locally to the root zone of the mugwort. S6. Harvest the above-ground parts of the Artemisia argyi 110-130 days after transplanting, and remove the above-ground parts of the Artemisia argyi from the cadmium-arsenic contaminated farmland. S7. After the harvest of Artemisia argyi, a hot water extract of Artemisia argyi for immediate use is obtained by hot water extraction of dried Artemisia argyi leaves and water. Commercial organic fertilizer, polyferric sulfate, potassium humate, oyster shell powder, the hot water extract of Artemisia argyi for immediate use and water are mixed and piled up to obtain a safe pre-season passivation material. The safe pre-season passivation material is applied to the cadmium and arsenic compound contaminated farmland after harvest and mixed into the topsoil.

2. The method for remediating cadmium and arsenic compound pollution in arable land based on Artemisia argyi extraction and organic material regulation according to claim 1, characterized in that, The cadmium-arsenic contaminated farmland refers to farmland with total cadmium of 0.980-1.780 mg / kg, total arsenic of 48-82 mg / kg, and pH of 5.4-6.8 in the 0-20cm topsoil layer. No food crops will be planted during the remediation season; only Artemisia argyi will be planted for cadmium activation and absorption and removal from the aboveground parts.

3. The method for remediating cadmium and arsenic compound pollution in arable land based on Artemisia argyi extraction and organic material regulation according to claim 1, characterized in that, At every 667m 2 According to the processing unit, the hot water extract of Artemisia argyi for modifying the outer layer of organic materials is prepared by the following method: 30-40 kg of dried Artemisia argyi leaves are added to 300-400 kg of water and extracted at 75°C for 2 hours. During the extraction, the mixture is stirred once every 20 minutes for 5 minutes each time. After the extraction, the mixture is filtered through an 80-mesh filter cloth. The filter residue is rinsed with 30-40 kg of water and the filtrates are combined. The combined filtrate is concentrated to 200-240 kg at 70°C, or water is added to 200-240 kg if the combined filtrate is less than the target mass, to obtain the hot water extract of Artemisia argyi for modifying the outer layer of organic materials.

4. The method for remediating cadmium and arsenic compound pollution in arable land based on Artemisia argyi extraction and organic material regulation according to claim 1, characterized in that, At every 667m 2 According to the processing unit, the directional modified organic material of Artemisia argyi extract is prepared by the following method: 105-150 kg of crop straw biochar, 270-360 kg of commercial organic fertilizer and 25-40 kg of potassium humate are mixed for 20-30 min, then 200-240 kg of hot water extract of Artemisia argyi for modifying the outer layer of organic material and 45-90 kg of water are added, and the mixture is mixed for another 30 min and then piled for 48-60 h. The pile temperature is controlled at 25℃, and the mixture is turned over once every 24 h during the pile period to obtain the directional modified organic material of Artemisia argyi extract.

5. The method for remediating cadmium and arsenic compound pollution in arable land based on Artemisia argyi extraction and organic material regulation according to claim 1, characterized in that, At every 667m 2 According to the processing unit, the inner cadmium-activated material is prepared by the following method: Take 400-500 kg of wormwood extract-modified organic material, add 5-12 kg of citric acid monohydrate, 8-14 kg of oyster shell powder and 70-100 kg of water, mix for 30 min and then pile at 20℃ to 35℃ for 24 h to obtain the inner cadmium-activated material.

6. The method for remediating cadmium and arsenic compound pollution in arable land based on Artemisia argyi extraction and organic material regulation according to claim 1, characterized in that, At every 667m 2 According to the processing unit, the outer arsenic migration control material is prepared by the following method: Take 290-340 kg of wormwood extract-modified organic material, add 20-35 kg of polyferric sulfate, 20-35 kg of oyster shell powder and 80-120 kg of water, mix for 30 min and then pile at 25°C for 48 h to 96 h. During the pile-up period, stir once every 24 h, and the piled material is not sealed to obtain the outer arsenic migration control material.

7. The method for remediating cadmium and arsenic compound pollution in arable land based on Artemisia argyi extraction and organic material regulation according to claim 1, characterized in that, The inner strip has a width of 22-30cm and a depth of 10-15cm. All the inner cadmium activation material is applied into the inner strip in equal amounts according to the total length of the inner strip, and then covered with 2-5cm of soil. The outer strip has a width of 8-12cm and a depth of 8-15cm. All the outer arsenic migration control material is applied into the outer strip in equal amounts according to the total length of the outer strip, and then covered with soil.

8. The method for remediating cadmium and arsenic compound pollution in arable land based on Artemisia argyi extraction and organic material regulation according to claim 1, characterized in that, At every 667m 2 For each treatment unit, 85-100 kg of Artemisia argyi seedlings are transplanted above the inner strip, with a plant spacing of 25-35 cm, a row spacing of 50-55 cm, and a transplanting depth of 6-10 cm. After transplanting, 400-600 kg of water is applied. Within 15 days after transplanting, the moisture content of the 0-20 cm tillage layer is controlled to 60% to 70% of field capacity. From 15 days after transplanting until harvest, the moisture content of the 0-20 cm tillage layer is controlled to 55% to 70% of field capacity.

9. The method for remediating cadmium and arsenic compound pollution in arable land based on Artemisia argyi extraction and organic material regulation according to claim 1, characterized in that, At every 667m 2 The preparation of the root zone activation solution for each treatment unit includes: adding 1.6-2.4 kg of dried Artemisia argyi leaves to 16-24 kg of water, extracting at 75°C for 1 hour, filtering through an 80-mesh filter cloth, and adjusting the volume to 8-12 kg to obtain a hot water extract of Artemisia argyi for immediate use. Then, 2-4 kg of citric acid monohydrate, 8-12 kg of the hot water extract of Artemisia argyi for immediate use, and 80-120 kg of water are mixed to obtain the root zone activation solution. The root zone activation solution is applied to the soil surface only along the radius of 8-12 cm from the base of the Artemisia argyi stem.

10. The method for remediating cadmium and arsenic compound pollution in arable land based on Artemisia argyi extraction and organic material regulation according to claim 1, characterized in that, At every 667m 2 For the treatment unit, the safe utilization of pre-season passivated materials is prepared and applied as follows: 1.5-3 kg of dried Artemisia argyi leaves are added to 15-30 kg of water and extracted at 75℃ for 1 hour. After filtration through an 80-mesh filter cloth, the volume is adjusted to 15-25 kg to obtain a post-harvest Artemisia argyi hot water extract. 150-220 kg of commercial organic fertilizer, 10-20 kg of polyferric sulfate, 8-15 kg of potassium humate, 10-20 kg of oyster shell powder, 15-25 kg of post-harvest Artemisia argyi hot water extract, and 120-180 kg of water are mixed for 30 minutes and piled at 25℃ for 24-48 hours. The resulting material is then evenly spread on the surface of the treatment unit and rotary tilled into the 0-15 cm tillage layer. After rotary tillage, 250-350 kg of water is applied to maintain the moisture content of the 0-20 cm tillage layer at 60%-70% of field capacity, and the layer is maintained for 10-20 days.

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