Treatment of agricultural land contaminated with salt, alkali, and heavy metals in dry polluted irrigated areas

Abstract

To provide a method for treating agricultural land contaminated with salt, alkali, and heavy metals in dry polluted irrigated areas. The method involves the following steps: selecting fields to be treated, determining the depth of soil contamination in the high and low terraces, removing the contaminated surface soil from each terrace and piling it on one side of the low terrace, digging trenches in the removed low terraces and piling the excavated soil on the other side, backfilling the removed contaminated soil layer by layer in the trenches, covering the surface of the refilled contaminated soil with the excavated soil to form new surface soil, establishing soil and groundwater environmental monitoring points in the backfilled areas, implementing soil fertility and other improvement measures for the new surface soil in each terrace, and planting corn varieties with low cadmium accumulation to complete the treatment of the contaminated soil. This significantly reduces the ecological risk of heavy metal contamination of saline-alkali cultivated land in contaminated irrigation areas, enabling the safe re-cultivation of heavily heavy metal-contaminated farmland.

Description

[Technical Field]

[0001] The present invention relates to the technical field of soil reclamation, specifically to the treatment of saline-alkali soils in dry, polluted irrigated areas. This invention relates to a method for treating agricultural land contaminated with multiple heavy metals. [Background technology]

[0002] Dry polluted irrigation areas are dry polluted irrigation areas located in arid or semi-arid climate zones, In areas with little annual rainfall and a significant discrepancy between agricultural water resource supply and demand, Areas where water or mixed wastewater is used as the main irrigation water source for agricultural production on a long-term basis Point. In recent years, the main remediation strategies for heavy metal contaminated agricultural soils include: adding soil conditioners; By strengthening the adsorption and fixation of heavy metals onto soil particles, we can utilize hyper- / hyperaccumulator plants to remove excess metals from the soil. Remove heavy metals and plant low-accumulator crops to reduce the heavy metal content in the edible parts of crops. Deep plowing is a common remediation technique for agricultural soil contamination. Research has shown that heavy metal-mixed contaminated agricultural soil Even if the soil is deep-ploughed, the contaminant content continues to exceed the standard value. The soil is then mixed with the soil in the upper layer, which has a high content of pollutants, and the soil in the lower layer, which has a relatively low content of pollutants. This is because there is a limit to the effect of reducing the contaminant content of surface soil in heavily contaminated soil with multiple heavy metals. If heterotopic repair methods are adopted, transportation and handling costs will increase significantly. Therefore, there is currently a lack of low-cost soil treatment methods that are highly effective in treating contaminated soil. do. Summary of the Invention

[0003] The methods for treating salt-alkali-heavy metal complex polluted farmland in dry polluted irrigated areas are as follows: The steps include: S1: Selecting fields to be treated from the contaminated farmland based on the degree of contamination of the contaminated farmland; S2: Next, the fields to be treated are divided into groups, and the fields within the same gradient range are classified into groups. A group of fields is obtained, and each group of fields in the plurality of groups of fields is composed of one high-level field and one low-level field. The same gradient range means that the gradient difference between fields is 0-10% and the upper level of each group of fields is 0-10%. The difference in elevation between the rice fields and the low-level fields is 1.0 to 3.0 m. S3, next, determine the depth of the contaminated soil in the high-grade field and the low-grade field, and Based on the depth, the contaminated soil in the fields to be treated is peeled off, and the contaminated soil after peeling is Obtaining high-level fields and low-level fields after peeling, The step of determining the depth of contaminated soil in the high terraced field and the low terraced field includes determining the depth of contaminated soil at multiple depths. and detect cadmium, lead, arsenic, and copper contents in soil at multiple depths. The plurality of depths are measured from the surface layer downward to a first depth, a second depth, ... and an n-th depth. The distance between two adjacent depths is 20 cm, and the cadmium in the soil at the nth depth is If the average contents of aluminum, lead, arsenic, and copper are all below the selected value or the regulated value, The depth value was taken as the depth of contaminated soil, S4: After the peeling, the high-level fields are directly fertilized and cultivated, then crops are planted and processed. Complete the After the above-mentioned separation, trenches were dug in the low-level fields, and the soil excavated from the trenches was collected and used for S3 by layered backfilling. The contaminated soil after peeling is backfilled in the trench and compacted, and then the soil excavated from the trench is used to and covering the lower terraced field after the peeling to obtain a treated lower terraced field; The layered backfilling method divides the contaminated soil after the peeling into layers every 10 cm. The trench is backfilled layer by layer until the distance between the contaminated soil and the top of the trench is 40 to 60 cm. After compaction, the soil excavated from the trench is divided into layers every 10 cm and placed at the same height as the top of the trench. The trench was then filled up until the soil was completely covered, and the remaining soil was dug up from the trench and spread evenly over the lower terraced fields. First, spread S5, 0.2 m, 0.5 m and 2.0 m from the outside of the furrow in the low-level field after the treatment, respectively Soil sampling points were set at 0.5 m and 3.0 m from the outer edge of the low-level fields after the treatment. and 30 m, respectively, and the soil sampling points were The soil in the groundwater sampling well and the groundwater in the groundwater sampling well were sampled periodically. and monitoring the soil in the soil sampling point or the groundwater sampling well. If the concentration of contaminants in groundwater during the survey increases over time, containment measures may be required. and collect soil or groundwater samples from the soil sampling points. If the concentration of the contaminant in the groundwater in the tank is monitored to not increase over time, This indicates that no contamination will be dispersed from the contaminated soil in the trenches of the terraced fields, and we can proceed to the next step. S6: Fertilize and cultivate the low-lying fields where the contamination does not spread, and then plant crops. , characterized by completing the treatment of salt-alkaline heavy metals in dry polluted irrigated areas. Methods for treating complex contaminated agricultural land. Contaminated soil is buried in a concentrated manner by backfilling and consolidating each layer, and the diffusion of heavy metal contaminants is reduced. Reduce risk and Furthermore, in the step S1, based on the degree of contamination of the contaminated farmland, The step of selecting fields to be treated from contaminated farmland is to examine the soil contamination status of the contaminated farmland and The fields containing cadmium, lead, arsenic and copper exceeding the selected or regulated values ​​are treated. This includes turning the land into farmland. Explanation: The above selected or regulated values ​​are based on the Soil Environmental Quality Standards for Agricultural Land Soil Contamination Risk Management and Control. (Trial)》(GB15618-2018) The allowable range value must not exceed the regulated value in the standard, and the safe usable range of lead, arsenic and copper must not exceed the regulated value in the standard. The value must not exceed the selected value in the standard. By setting the relative height between the high-level fields and the low-level fields, the local topography and water flow direction can be adjusted. This can avoid changing the direction. Furthermore, in the step S3, the peeling method includes: For each group of fields, the high-level fields and the low-level fields are divided into layers every 10 cm, and the surface soil is The contaminated soil is then peeled off layer by layer down to the depth of the contaminated soil, and the peeled contaminated soil is then placed in the low-level fields. The key is to build up the Explanation: By checking the depth for each layer using the above method, the safe usable depth can be determined. The selected or regulated values ​​are the Soil Environmental Quality Agricultural Land Soil Contamination Risk Management and Control Standards ( Please refer to GB15618-2018 (Trial) and the safe use of cadmium. The safe usable range values ​​for lead, arsenic and copper must not exceed the regulated values ​​in the standards. must not exceed the value selected in the standard. Furthermore, in S4, the position of the groove and the low-level field edge after peeling are The distance between the trenches is greater than 2.0 m, and the depth of the trench, the excavation area of ​​the trench and the contaminated soil The relationship between soil depth and the area of ​​the field to be treated is given by the following formula: JPEG0007810870000002.jpg3061+ In the JPEG0007810870000003.jpg1517 formula, JPEG0007810870000004.jpg1223 is the depth of the groove, JPEG0007810870000005.jpg1516 is the excavation area of ​​the trench, JPEG0007810870000006.jpg128 is the depth of the contaminated soil, JPEG0007810870000007.jpg1417 is the area of ​​the fields to be processed, JPEG0007810870000008.jpg1510 is the soil and stone volume conversion coefficient, JPEG0007810870000009.jpg1512 is the groove opening reserve coefficient. Explanation: Using the above formula, calculate the appropriate trench dimensions based on the amount of contaminated soil, and then calculate the average size of the field after stripping. At the same time, this design ensures that the contaminated soil is buried properly and that the soil Reduce the risk of spreading contaminants. Furthermore, the tillage depth is 18 to 25 cm, and the crop is corn, Explanation: The above thickness and tillage depth are highly practical and are suitable for growing the main local crops, wheat, soybeans, and sesame. Compared to other crops, corn has excellent cadmium-lowering effects and Cadmium accumulation can be reduced. Furthermore, in S5, the diffusion prevention measures are as follows: Excavate an isolation trench with a length of 0.5 to 2 m, a width of 0.2 to 0.4 m, and a depth equal to the trench depth. The groove is filled with a pollution prevention filler, the pollution prevention filler being 100 parts by weight of quicklime. parts and 100 parts attapulgite. Description: The installation of isolation trenches prevents the diffusion and movement of heavy metals in contaminated soil and prevents the filling of fillers. By adjusting the raw materials and mixing ratio, the precipitation and adsorption performance of the composite filler can be improved, and the heavy It fixes and stabilizes metal ions, reducing their movement and diffusion in the environment. Furthermore, several civil engineering standard rooms are installed at the edge of low-level fields after processing in S4. Then, upland fescue plants were planted in each civil engineering standard room, and the civil engineering standard rooms were then covered with nonwoven fabric. The standard civil engineering room is made of a plastic lattice structure. It further includes a step. Description: The civil engineering standard room effectively fixes the soil and prevents soil erosion caused by rainwater erosion. The root systems of upland fescue plants further stabilize the soil and reduce erosion. The civil engineering standard room has a lattice structure that increases the shear strength of the soil and prevents side slopes. The nonwoven fabric covering can improve the overall stability of the surface. It reduces the impact on slope soil, while also retaining heat and moisture, preventing excessive evaporation of water. It can prevent the roots from growing and promote the root growth and germination of plants. The method of the present invention involves stripping and backfilling heavily contaminated cultivated soil, and then re-establishing the soil and groundwater circulation in the backfilled area. Boundary monitoring points will be set up and soil fertility and other improvement measures will be implemented on the newly formed surface soil. It restores soil productivity, improves soil quality, and promotes corn production with low cadmium accumulation. By planting seeds, it is possible to safely re-cultivate heavily heavy metal contaminated farmland. Ecological analysis of heavy metal contamination in saline-alkaline farmland in contaminated irrigated areas through multi-technical collaborative treatment This will significantly reduce the chemical risks and ensure the sustainable use of contaminated farmland. [Brief explanation of the drawings]

[0004] [Figure 1] FIG. 10 is a diagram showing the distribution data of Cd in the total amount of contaminated soil in Example 2 of the present invention. [Figure 2]FIG. 10 is a data chart showing the change in Cd content before and after removal of contaminated soil in Example 2 of the present invention. [Figure 3] FIG. 10 is a graph showing the distribution data of total soil Pb in Example 2 of the present invention. [Figure 4] FIG. 10 is a data chart showing the change in Pb content before and after removal of contaminated soil in Example 2 of the present invention. [Figure 5] FIG. 10 is a graph showing the distribution of total soil As and its change before and after peeling in Example 2 of the present invention. [Figure 6] FIG. 10 is a data chart showing the change in As content before and after removal of contaminated soil in Example 2 of the present invention. [Figure 7] FIG. 10 is a diagram showing the Cu distribution in the total amount of soil and the change before and after peeling in Example 2 of the present invention. [Figure 8] FIG. 10 is a data chart showing the change in Cu content before and after contaminated soil removal in Example 2 of the present invention. [Figure 9] FIG. 1 shows the Cd content in corn seeds after normal deep plowing and soil removal in Example 2 of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0005] As can be seen from the background art above, dry polluted irrigation areas are those located in arid or semi-arid climate zones. In areas with little annual rainfall and a significant discrepancy in agricultural water supply and demand, Areas where industrial wastewater or mixed sewage is used as the main irrigation water source for long-term agricultural production irrigation. When heavy metals such as cadmium invade alkaline soil, they are mainly concentrated in the cultivated layer (0-20°C). m) Adsorbed and precipitated by soil, remaining in the soil layer for a long period of time, and deep soil layers (>20 cm) Salt in soil affects the mobility and bioavailability of heavy metals. and significantly alter the environmental and health risks of heavy metal contamination in saline-alkaline soils. Studies have shown that there are complex interactions between heavy metals such as Cd and basic ions, for example For example, Na in soil+ The basic ions such as these are replaced by heavy metal ions adsorbed on the soil surface. This replaces nitrates and improves the mobility and bioavailability of soil heavy metals. From the above, it can be seen that the complexity of salt-alkaline, heavy metal-contaminated soil makes remediation difficult. The actual remediation process involves a combination of various methods such as soil improvement, phytoremediation, and chemical remediation. This needs to be taken into consideration. Reducing the level of heavy metal contamination in saline-alkaline soil while ensuring safe crop production To this end, embodiments of the present invention provide the following feasible methods: Example 1: Treatment method for salt-alkali-heavy metal complex polluted farmland in dry polluted irrigated areas The method includes the following steps: S1: Based on the degree of contamination of the contaminated farmland, select fields to be treated from the contaminated farmland and specify The soil contamination status of contaminated farmland was investigated, and the levels of cadmium, lead, arsenic, and copper in the soil were measured. Fields with content exceeding the selected or regulated value are considered to be fields that should be treated. S2: Then, the fields to be treated are divided into groups, and the fields within the same slope range are classified into groups. The distribution range means that the difference in slope between fields is 0 to 10% (for example, 5%). A field is obtained, and each group of fields in the plurality of fields includes one high-level field and one low-level field, The difference in elevation between the high and low fields in each group of fields is 2.0 m. S3: Then, determine the depth of contaminated soil in high-level fields and low-level fields, and based on the contaminated soil depth, Based on this, the contaminated soil from the fields to be treated will be removed and the contaminated soil after removal, the high-level fields after removal, and and obtain low-level fields after peeling, The step of determining the contaminated soil depth in high-level fields and low-level fields is Soil is sampled and detected at multiple depths, and cadmium, lead, arsenic, and The copper content is obtained, and the multiple depths are the first depth, the second depth, and the nth depth from the surface layer downward. The distance between two adjacent depths is 20 cm, and the cadmium in the soil at the nth depth is If the average contents of aluminum, lead, arsenic, and copper are all below the selected or regulated values, The value of the degree is the contaminated soil depth, The peeling method is as follows: for each group of fields in multiple groups, high-level fields and low-level fields are The soil is divided into layers every 10 cm, and the contaminated soil is peeled off layer by layer from the surface soil to the contaminated soil depth. The contaminated soil after removal is piled up on the low-lying fields after removal, S4: After peeling, direct fertilization and cultivation are carried out on the high-level fields, and then crops are planted to complete the treatment. Done, After the soil is removed, trenches are dug in the low-level fields, and the soil is dug out from the trenches and backfilled layer by layer. The contaminated soil removed in step 3 is backfilled in the trench and compacted, and then the soil excavated from the trench is used Cover the trench and the lower terraced fields after peeling to form the lower terraced fields after treatment. The distance between the location of the trench and the edge of the low-level field after separation is 3.0 m. The depth of the trench and the excavation area of ​​the trench are The relationship between the depth of contaminated soil and the area of ​​fields to be treated is shown in the following formula: JPEG0007810870000010.jpg3061+ In the JPEG0007810870000011.jpg1517 formula, JPEG0007810870000012.jpg1223 is the depth of the groove, JPEG0007810870000013.jpg1516 is the excavation area of ​​the trench, JPEG0007810870000014.jpg128 is the depth of the contaminated soil, JPEG0007810870000015.jpg1417 is the area of ​​the fields to be processed, JPEG0007810870000016.jpg1610 is the soil and stone volume conversion coefficient, JPEG0007810870000017.jpg1612 is the groove opening reserve coefficient, JPEG0007810870000018.jpg1610 is the ratio of the soil volume after actual consolidation to the original soil volume, and is used to determine the compression characteristics and Reflecting the compaction effect, JPEG0007810870000019.jpg1610 depends on factors such as soil type and soil moisture content (value range: 0.67 to 1.0), and In the examples, JPEG0007810870000020.jpg1610 has a value of 0.87, JPEG0007810870000021.jpg1612 is related to the plant root distribution, and its value must be equal to or greater than the plant root distribution depth. For example, In order to avoid plant root growth into contaminated soil, if the plant root system is distributed in the soil 0.2 m, , 0.4m is adopted, Here, the area of ​​the groove JPEG0007810870000022.jpg1516 JPEG0007810870000023.jpg1660, where a is the length of the field L-4 m and b is the width of the field M-4 m. The layered backfilling method is as follows: After stripping, the contaminated soil is divided into layers every 10 cm. The trench is backfilled and compacted layer by layer until the distance between the contaminated soil and the top of the trench is 40 cm. After that, the soil excavated from the trench was divided into layers every 10 cm, and the trench was filled with soil until it reached the same height as the top of the trench. The soil excavated from the remaining trenches is then spread evenly over the lower terraced fields after removal. Excavate an isolation trench 0.5m from the outer edge of the trench, 0.2m wide and as deep as the trench itself. The groove is filled with a pollution prevention filler, which is composed of 100 parts by weight of quicklime and and 100 parts of attapulgite, Here, the thickness of the soil excavated from the trench backfilled in the trench is 40 cm, and the tillage depth is 20 cm, the crop is corn, S5: Soil at 0.2 m, 0.5 m, and 2.0 m from the outside of the furrow in the low-level field after treatment, respectively Sampling points were set at 0.5 m, 3.0 m and 3 m from the outer edge of the low-level fields after treatment. Set up groundwater sampling wells at 0 m and soil sampling points. and groundwater in the groundwater sampling wells should be sampled and monitored periodically to Contaminant concentrations in the soil at the sampling points or in the groundwater at the groundwater sampling wells If an increase in concentration over time is observed, containment measures should be taken and soil samples should be collected. Contaminant concentrations in the soil at sampling points or in the groundwater at groundwater sampling wells change over time. When monitoring that the concentration did not increase over time, the diffusion of contaminants from contaminated soil in the trenches of low-level fields was Indicates that this does not occur and proceeds to the next step. Diffusion prevention measures include irrigation volume management and over-irrigation to prevent pollutants from seeping in with the water. The method of improving the isolation is to replace the filler of the isolation groove or or widening of the isolation trench, S6: Several standard civil engineering chambers (40cm x 40cm x 15cm) were installed at the edge of the low-level fields after treatment. ) and planted plants such as highland fescue in each civil engineering standard room. The plants are covered with nonwoven fabric and watered regularly. a lattice structure made of S7: Fertilize and cultivate low-lying fields where contamination does not spread, then plant crops and treat them. Complete the analysis. Example 2: Illustratively, salt-alkaline heavy metal complex polluted farmland in a dry polluted irrigated area The processing method includes the following steps S1 to S7: S1: Based on the degree of contamination of the contaminated farmland, select fields to be treated from the contaminated farmland and Selected agricultural land with salt-alkaline and heavy metal complex contamination in the area, and clear distribution of the contamination among the selected fields. Specifically, the remediation of salt-alkaline heavy metal complex contaminated soil in a certain area of ​​a certain city. A physical test was conducted to examine the soil environmental quality of a certain area in a certain city, and the results showed that the area The total salt content of agricultural soil in the area reached 3.29±0.21g / kg, and the surface layer 0-20cm of the area The total Cd, Pb, As, and Cu contents in the soil were 71.2±32.6 mg / kg, 826±768mg / kg, 43.9±26.2mg / kg and 263±159 mg / kg, both of which comply with the Standards for Soil Environmental Quality and Control of Agricultural Land Soil Contamination Risk (GB 15618-2018) or exceed the selection value or regulation value specified, S2, then, divide the fields to be processed into groups, and classify the fields within the same gradient range into groups. Each group of fields contains one high-grade field and one low-grade field. In the case of multiple groups of fields, the difference in altitude between the high and low fields of each group of fields is 2.0 m or more. Specifically, the two fields, the high-grade field and the low-grade field, are used to grow crops such as corn, wheat, or soybeans. The total area is approximately 900m 2 The high-level fields are about 500m 2 And low-lying rice fields The height is about 400m 2 Both fields are soils contaminated with salt, alkali, and heavy metals. The distribution of total soil Cd, Pb, As and Cu is shown in Figures 1, 3, 5 and 7. The exam period is from September 2021 to October 2021. S3: Then, determine the depth of contaminated soil in high-level fields and low-level fields, and based on the contaminated soil depth, Based on this, the contaminated soil from the fields to be treated will be removed and the contaminated soil after removal, the high-level fields after removal, and Specifically, in September 2021, soil drilling was carried out using the grid layout method. Before peeling, soil samples were collected from 0-20cm, 20-40cm, and 40-60cm. Then, a large loader was used to remove the contaminated soil layer by layer from 0 to 40 cm in high and low fields. The soil thickness was 10cm, and the soil was peeled a total of four times. S4: In the low-level fields after stripping, a trench was dug 2.0 m from the edge of the low-level fields using an excavator. The soil excavated from the trench and the contaminated soil after surface peeling were piled up separately. of contaminated soil was backfilled into the trench and compacted layer by layer. The soil excavated from the trench 40 cm from the opening Backfill the soil layer by layer, compacting it layer by layer until it is flush with the trench opening, then stop backfilling and continue for the remaining The soil excavated from the trenches is spread evenly on the surface of the low-level fields, and a level and and using a leveller to ensure the terrain is flat. S5: Soil at 0.2 m, 0.5 m, and 2.0 m from the outside of the furrow in the low-level field after treatment, respectively Sampling points were set at 0.5 m, 3.0 m and 3 m from the outer edge of the low-level fields after treatment. Set up groundwater sampling wells at 0 m and soil sampling points. and groundwater in the groundwater sampling wells should be sampled and monitored periodically to Contaminant concentrations in the soil at the sampling points or in the groundwater at the groundwater sampling wells If an increase in concentration over time is observed, containment measures should be taken and soil samples should be collected. Contaminant concentrations in the soil at sampling points or in the groundwater at groundwater sampling wells change over time. When monitoring that the concentration did not increase over time, the diffusion of contaminants from contaminated soil in the trenches of low-level fields was Indicates that this does not occur and proceeds to the next step. For example, soil and groundwater sampling at soil sampling points every two months The groundwater in the wells is sampled and monitored, and in addition, large ponds set up in the fields are used every two months. Relevant samples were taken from the air particle settling collector and the outlet of the irrigation channel, and the contaminated soil was also buried. After the return, a soil-side infiltration water collection device was installed on the outside of the footpaths of the low-level fields. Even in large cases, no water samples were observed seeping from within the fields. Changes in total Cd, Pb, As, and Cu contents in the surface soil (0-20 cm) before and after stripping The situation is shown in Figures 2, 4, 6 and 8. Compared to before peeling, the total amount of Cd, Pb, A The contents of S and Cu were 95.6%, 84.7%, 51.2% and 71.1%, respectively. As can be seen from the results, the salt-alkali heavy metal complex polluted agricultural land in the study area After the soil was stripped, the level of heavy metal contamination in the newly formed surface soil was significantly reduced. The newly formed cultivated layer meets the requirements for safe utilization research, and after peeling, The cultivated soil is maintained according to field management standards, including measures such as weed removal and winter irrigation. It is managed to optimize soil environmental conditions and support the next year's crop cultivation work. S6: Several standard civil engineering chambers (40cm x 40cm x 15cm) were installed at the edge of the low-level fields after treatment. ) and planted plants such as highland fescue in each civil engineering standard room. The plants are covered with nonwoven fabric and watered regularly. It should be noted that the civil engineering standard room is a standard commercially available product. For example, the domestic and international standards are as follows: China: GB / T 19274-2017 {Civil Engineering Composite Materials, Plastic Civil Engineering Standards Office} Bikuni: ASTM D7864 (Standard Test Method) The specific dimensions and mechanical parameters of the civil engineering standard room can be selected by a person skilled in the art as needed. (A certain brand of HDPE construction standard room) is sufficient, and the present invention is not particularly limited, S7: Fertilize and cultivate fields where contamination does not spread, then plant crops and perform treatment. Completed, Specifically, organic matter made from agricultural and forestry waste is rich in organic matter and has the potential to improve, cultivate, and promote soil It helps to promote crop growth and is effective in soil peeling process. To reduce heavy metal concentrations, the original cultivated soil was stripped and backfilled, and new soil was created. The cultivated soil is relatively poor, so the soil quality can be improved effectively by applying a large amount of organic matter. This will improve the environment for growing crops. After the start of the cultivation season, organic matter is spread on the fields (winter irrigated) after peeling, and after plowing, the organic matter and new Mix the cultivated soil thoroughly, build and cultivate good new soil, and improve the quality of the cultivated soil after reconstruction. Improved fertility and productivity, with organic matter N:P:K content of 5.45±0.26g / kg, 1.97±0.07g / kg and 18.75±0.92g / kg, respectively, and organic matter The content was 75.5±2.3g / kg, and the amount of organic matter applied was 6T / furrow, and it was applied continuously for three years. This is a plan to Preferably, maize varieties with drought tolerance, high yield, high lodging resistance, and low cadmium uptake. Select "Kinen 007" and apply basal fertilizer (compound fertilizer: N-P2O5-K2O15-15-15) before cultivation. ) was applied at a rate of 40 kg / row, and the corn was grown at 10-12 leaves. A mixture of diammonium hydrogen carbonate (2 parts) and urea (1 part) was applied as a top dressing. The fertilizer was applied by digging holes and covering the soil. The amount of fertilizer to be applied after mixing is 30 kg per ridge, and it should be applied before 10:00 a.m. or after 4:00 p.m. when there is no wind or rain. 55% nitrosulfazole-atrosin herbicide was applied to corn at the 3-5 leaf stage at a rate of 150 times. Dilute and spray at a rate of 200g / row, and after winter irrigation in the previous year, cultivate and till the soil. Through moisture retention, the water demand of corn seedlings is met, and then the water demand of corn seedlings is met at 10 to 12 leaves. After top dressing, irrigation was carried out at the internode elongation, ear formation, ear emergence, flowering and maturity stages. After ripening, the mustard and seeds were harvested, washed, dried, and crushed, and then digested. The concentrations were measured by ICP-MS, and the data obtained from the test treatments was analyzed using Excel 2013 and The data were analyzed using SPSS 16.0 software, and the differences between the different treatments were analyzed using analysis of variance (L The results were evaluated by multiple comparisons using standard deep plowing and soil stripping. The change in Cd content in the newly formed cultivated layer after the soil stripping treatment is shown in Fig. 9. The cadmium content in the corn seeds was significantly reduced, resulting in a reduction in the cadmium content in the corn seeds. did. Example 3: This example differs from Example 2 in the following points: The height difference between the two is 1.0 m, and a 0.2 m wide isolation trench is excavated 0.5 m from the edge of the trench. Fill the separation trench with filler until the distance between the separated soil and the upper edge of the trench is 40 cm at S4. The trench was backfilled layer by layer and compacted, and the soil excavated from the trench at S4 was 40 cm thick. The tillage depth is 18cm and the crop is corn. Example 4: This example differs from Example 2 in the following points: The elevation difference between the two is 3.0 m, and a 0.4 m wide isolation trench is excavated 2 m from the edge of the trench. Filler was then added to the trench at S4 until the distance between the soil and the trench top edge was 60 cm. Layer by layer, the soil excavated from the trench at S4 was backfilled and compacted to a thickness of 60 cm. The tillage depth is 25 cm and the crop is corn.

Claims

1. A method for treating agricultural land contaminated with salt, alkali, and heavy metals in dry polluted irrigation areas 、 S1: A step of selecting fields to be treated from the contaminated farmland based on the degree of contamination of the contaminated farmland. Top and S2: Next, the fields to be treated are divided into groups, and the fields within the same gradient range are classified into groups. A group of fields is obtained, and each group of fields in the plurality of groups of fields is composed of one high-level field and one low-level field. The same gradient range means that the gradient difference between fields is 0 to 10%, and the upper level of each group of fields is The difference in elevation between the rice fields and the lower fields is 1.0 to 3.0 m. S3: Next, the depth of the contaminated soil in the high-level fields and the low-level fields is determined, and the depth of the contaminated soil is calculated. Based on the depth, the contaminated soil in the fields to be treated is peeled off, and the contaminated soil after peeling is Obtaining high-level fields and low-level fields after peeling, The step of determining the depth of contaminated soil in the high terraced field and the low terraced field includes determining the depth of contaminated soil at multiple depths. and detect cadmium, lead, arsenic, and copper contents in soil at multiple depths. The plurality of depths are measured from the surface layer downward to a first depth, a second depth, ... and an nth depth. The distance between two adjacent depths is 20 cm, and the cadmium in the soil at the nth depth is If the average contents of aluminum, lead, arsenic, and copper are all below the selected value or the regulated value, taking the depth value as the depth of the contaminated soil; S4: After the peeling, the high-level fields are directly fertilized and plowed, then crops are planted and processed. Complete the After the peeling, trenches are dug in the low-level fields, and the soil excavated from the trenches is collected and used for S3 by layered backfilling. The contaminated soil after peeling is backfilled in the trench and compacted, and then the soil excavated from the trench is used to and covering the lower terraced field after the peeling to obtain a treated lower terraced field; The layered backfilling method divides the contaminated soil after the peeling into layers every 10 cm. The trench is backfilled and compacted layer by layer until the distance between the contaminated soil and the top of the trench is 40-60 cm. The soil excavated from the trench was then divided into layers every 10 cm, and the layers were placed at the same height as the top of the trench. The trenches were then backfilled until the soil was completely removed, and the remaining soil excavated from the trenches was spread evenly over the lower terraced fields after the removal. a dispersing step; S5, at 0.2 m, 0.5 m and 2.0 m from the outside of the furrow in the low-level field after the treatment, respectively Soil sampling points were set at 0.5 m and 3.0 m from the outer edge of the low-level fields after the treatment. and 30 m, respectively, and the soil sampling points were The soil in the groundwater sampling well and the groundwater in the groundwater sampling well were sampled periodically. and monitoring the soil in the soil sampling point or the groundwater sampling well. If the concentration of contaminants in groundwater during the survey increases over time, containment measures may be required. and the soil or groundwater sampling wafers in the soil sampling points are If the concentration of the contaminant in the groundwater in the tank is monitored to not increase over time, Step to show that no contamination will be dispersed from the contaminated soil in the trenches of the terraced fields, and proceed to the next step and, The diffusion prevention measures are as follows: 0.5-2 m from the outer edge of the trench, 0.2 m wide An isolation trench is excavated with a depth of up to 0.4 m and the same as the trench depth, and a contamination diffusion prevention filler is placed in the isolation trench. The contamination diffusion prevention filler is composed of 100 parts by weight of quicklime and 1 part by weight of attapulgite. Including 00 parts, S6: Fertilize and cultivate the low-lying fields where the contamination does not spread, and then plant crops. , completing the process; A method for treating salt-alkaline, heavy metal-complex contaminated agricultural products in arid, contaminated irrigated areas, comprising: How to treat the ground.

2. In the step S1, the fields to be treated are selected from the contaminated farmland based on the degree of contamination of the contaminated farmland. The selection step involves examining the soil contamination status of contaminated farmland and determining the levels of cadmium, lead, arsenic, and and to designate fields where the copper content exceeds the selected or regulated value as fields to be treated.

2. The method of claim 1 .

3. In the step S3, the peeling method includes: The fields and the low-level fields were divided into layers every 10 cm, and the contaminated soil was removed from the surface soil to the depth of the contaminated soil. The contaminated soil is then peeled off layer by layer, and the peeled off contaminated soil is piled up on the lower terraced fields. The method of claim 1, further comprising:

4. In S4, the distance between the position of the groove and the edge of the low-level field after peeling is less than 2.0 m. The depth of the trench, the excavation area of ​​the trench and the depth of the contaminated soil, the area of ​​the fields to be treated The relationship between the areas is shown in the following formula: + In the formula: is the depth of the groove, is the excavation area of ​​the trench, is the depth of the contaminated soil, is the area of ​​the fields to be treated, is the soil and stone volume conversion coefficient, 2. The method of claim 1, wherein: is a groove opening reserve factor.

5. After processing in S4, multiple civil engineering standard rooms are installed on the edge of the low-level fields, and each civil engineering standard room After planting highland fescue plants in the ground, the standard civil engineering room was covered with nonwoven fabric and watered regularly. and the civil engineering standard room is a plastic lattice structure.

2. The method of claim 1, comprising:

Images