A method for enriching soil in a rice field based on the immobilization effect of perfluorocompounds

Abstract

The present application belongs to the field of fertilization and planting technology in the technology of cultivated soil remediation, and provides a rice field soil fertilization method based on the immobilization effect of perfluorinated compounds. The background value of perfluorinated compound pollution in the rice field soil polluted by perfluorinated compounds is investigated, the pollutant type of perfluorinated compound background pollution is determined, the immobilization effect of several fertilizers on perfluorinated compounds in the rice field soil is evaluated according to the pollutant type, and the fertilization scheme is selected according to the evaluation result of the immobilization effect of perfluorinated compounds. The pollutant type includes ultra-short chain, short chain or long chain perfluorinated compounds. The immobilization promotion effect of ammonium chloride on ultra-short chain perfluorinated compounds is the best, and the immobilization promotion effect of wheat straw biochar on short chain and long chain is the best, which indicates that the separate / combined use of ammonium chloride and wheat straw biochar can further realize the immobilization remediation of perfluorinated compounds with different chain lengths on the basis of improving the fertility of cultivated soil.

Description

Technical Field

[0001] This invention belongs to the field of fertilization and planting technology in arable land soil remediation technology, and particularly relates to a method for increasing soil fertility in paddy fields based on the immobilization effect of perfluorinated compounds. Background Technology

[0002] In recent years, industrial pollutants have entered paddy field soils through atmospheric dry and wet deposition, surface runoff, irrigation, and biosolids application, endangering agricultural production and human food security. Among the many pollutants, perfluorinated compounds (PFCCs) have received widespread attention. PFCCs are a class of artificially synthesized organic compounds in which all hydrogen atoms in the main carbon chain are replaced by fluorine atoms. Due to the presence of carbon-fluorine bonds, PFCCs exhibit high chemical persistence and carcinogenicity, and cannot be naturally degraded in the environment, becoming highly hazardous permanent chemicals. Once they enter arable soil, PFCCs are almost permanently present and absorbed by rice crop roots. Based on chain length, PFCCs can generally be divided into three categories: ultrashort chains (2-3 carbon atoms in the main carbon chain), short chains (4-7 carbon atoms in the main carbon chain), and long chains (8 or more carbon atoms in the main carbon chain). In the daily management of paddy fields, ultra-short-chain and short-chain perfluorinated compounds (PFOCs) diffuse and migrate at the soil-water interface under the hydraulic disturbance of irrigation and drainage. Long-chain PFOCs, due to their weaker migration capacity, are more likely to remain persistently in the soil in a stable adsorbed state and are then enriched and transferred to aboveground parts by crop roots. Furthermore, improving the fertility of paddy field soils has always been a challenge in rice cultivation and fertilizer application, given the high intensity of farming, severe soil erosion, and increasing soil depletion. Based on this approach, simultaneously immobilizing PFOCs and effectively replenishing paddy field soil fertility aligns with the strategic planning for the control of new pollutants and the improvement of arable land soil quality.

[0003] For example, patent (publication number CN115591926A): an ecological remediation method for soil contaminated with perfluoropolyfluoroalkyl compounds. In this patent, phytoremediation of perfluorinated compound pollution is a relatively conventional soil remediation strategy, which does not have the effect of simultaneously adapting to the immobilization and soil fertility improvement of perfluorinated compound pollution scenarios with different chain lengths. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a method for enhancing paddy field soil fertility based on the immobilization effect of perfluorinated compounds, aiming to solve the problems mentioned in the background art. This invention can effectively remediate arable land soil pollution caused by perfluorinated compounds, a new type of pollutant, by both improving its immobilization effect and enhancing soil fertility.

[0005] This invention provides a method for fertilizing paddy soil based on the immobilization effect of perfluorinated compounds. The method involves investigating the background level of perfluorinated compound pollution in paddy soil, determining the types of pollutants involved in the background pollution, evaluating the immobilization effect of several fertilizers on perfluorinated compounds in paddy soil based on the pollutant types, and selecting a fertilization scheme based on the evaluation results of the perfluorinated compound immobilization effect. The pollutant types include ultra-short-chain, short-chain, or long-chain perfluorinated compounds.

[0006] Furthermore, the effects of several fertilizers on the immobilization of perfluorinated compounds in paddy soil were evaluated, specifically including the following steps: Several fertilizers were added to paddy field soil at a mass percentage of 5% of the perfluorinated compound contaminated soil, and mixed thoroughly. A blank control group without fertilizer was set up. After 14 days, deionized water was added. Several paddy field soil samples were collected on the 21st day after the addition of deionized water. Based on the quantitative values ​​of perfluorinated compound immobilization effects from several paddy field soil samples, the average perfluorinated compound immobilization effects of ultra-short chain, short chain, or long chain perfluorinated compounds in the background pollution of perfluorinated compounds were statistically analyzed, and the evaluation results of the immobilization effects of several fertilizers on perfluorinated compounds in paddy field soil were obtained.

[0007] Furthermore, the method for obtaining the quantitative value of the immobilization effect of perfluorinated compounds is as follows: perfluorinated compounds in paddy soil contaminated with perfluorinated compounds are continuously extracted in segments to obtain several forms of perfluorinated compounds, namely, overlying water, soil interstitial water, microbial adsorbed state, cationic bound state, and stable bound state; the concentration of perfluorinated compounds in several forms is detected, and the ratio of the concentration of perfluorinated compounds in the stable bound state to the total concentration of perfluorinated compounds in several forms is calculated to obtain the quantitative value of the immobilization effect of perfluorinated compounds in paddy soil contaminated with perfluorinated compounds.

[0008] Furthermore, several types of fertilizers include ammonium chloride, potassium nitrate, urea, chicken manure, sheep manure, earthworm castings, corn straw biochar, rice straw biochar, and wheat straw biochar.

[0009] Furthermore, the ultrashort-chain perfluorinated compounds include trifluoroacetic acid / perfluoroacetic acid (TFA) and pentafluoropropionic acid / perfluoropropionic acid (PFPrA); Short-chain perfluorinated compounds include perfluorobutyric acid (PFBA), perfluorovalerate (PFPeA), perfluorohexanoic acid (PFHxA), perfluoroheptanoic acid (PFHpA), perfluorobutane sulfonic acid (PFBS), perfluorohexane sulfonic acid (PFHxS), and hexafluoropropylene oxide dimer acid (HFPO-DA). Long-chain perfluorinated compounds include perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDA), perfluoroundecanoic acid (PFUnDA), perfluorododecanic acid (PFDoA), perfluorotetradecanoic acid (PFTeDA), hexafluoropropylene oxide trimeric acid (HFPO-DA), chromium mist inhibitor (F-53B), and sodium perfluorononenoxybenzenesulfonate (OBS).

[0010] Furthermore, the paddy field soil is paddy field soil from the fallow period.

[0011] Furthermore, a continuous, segmented extraction process was performed on the perfluorinated compounds in paddy soil, specifically including the following steps: The overlying water body is collected to detect the concentration of perfluorinated compounds in the overlying water body, and then the overlying water body is discharged to obtain freshly precipitated paddy soil. Weigh paddy soil, add deionized water, mix thoroughly and shake, then vortex to obtain the first water-soil mixed suspension. After sonication of the first water-soil mixed suspension, centrifuge to obtain the first soil precipitate and the first supernatant. The first supernatant is used to detect the perfluorinated compound concentration of perfluorinated compounds in soil pore water. Physiological saline was added to the first soil precipitate, and after thorough mixing and shaking, the mixture was vortexed to obtain the second water-soil mixed suspension. The second water-soil mixed suspension was heated at 70°C and sonicated, and then centrifuged to obtain the second soil precipitate and the second supernatant. The second supernatant was used to detect the concentration of perfluorinated compounds in the microbial adsorbed state. A cationic strong electrolyte solution was added to the second soil precipitate, and the mixture was thoroughly mixed and shaken. The mixture was then vortexed to obtain a third water-soil mixed suspension. The third water-soil mixed suspension was sonicated and centrifuged to obtain a third soil precipitate and a third supernatant. The third supernatant was used to detect the concentration of perfluorinated compounds in cationic bound state. Methanol was added to the third soil precipitate, and after thorough mixing and shaking, the mixture was vortexed to obtain the fourth water-soil mixed suspension. The fourth water-soil mixed suspension was heated at 60°C and sonicated, then centrifuged to obtain the fourth soil precipitate and the fourth supernatant. The fourth supernatant was used to detect the concentration of perfluorinated compounds in a stable bound state.

[0012] Further, weigh 15 grams of paddy field soil and add 10 ml of deionized water; add 10 ml of physiological saline to the first soil precipitate; add 10 ml of 0.01 mol / L cationic strong electrolyte solution to the second soil precipitate; and add 10 ml of methanol to the third soil precipitate.

[0013] Furthermore, the cationic strong electrolyte solution is a mixture of magnesium chloride and calcium chloride in equal proportions.

[0014] Furthermore, the specific weight gain plan is as follows: When the main pollutant type in the background pollution of perfluorinated compounds is ultrashort-chain perfluorinated compounds, the recommended fertilization program for paddy field soil is ammonium chloride. When the main pollutant type of background pollution is short-chain or long-chain perfluorinated compounds, the soil fertilization program for paddy fields should be wheat straw biochar.

[0015] The present invention has the following beneficial effects: (1) By identifying the types of pollutants causing background pollution of perfluorinated compounds, the effects of several fertilizers on the immobilization of perfluorinated compounds in paddy soil were evaluated based on the pollutant types in order to select fertilization strategies. Among them, ammonium chloride showed the best effect on improving the immobilization of ultra-short-chain perfluorinated compounds, while wheat straw biochar showed the best effect on improving the immobilization of both short-chain and long-chain perfluorinated compounds. This indicates that the individual or combined use of ammonium chloride and wheat straw biochar can further achieve the immobilization and remediation of perfluorinated compounds of different chain lengths on the basis of improving soil fertility.

[0016] (2) Immobilization and remediation of arable land soil pollution caused by perfluorinated compound pollutants with different chain lengths can simultaneously improve the quality of arable land by enhancing soil fertility in paddy fields. This approach achieves agricultural ecological risk management through perfluorinated compound immobilization while simultaneously improving paddy field soil fertility, demonstrating high environmental friendliness and green agricultural value. From the perspective of green agriculture and ecological environmental friendliness, this approach can be applied on a large scale to soil remediation work in intensive paddy fields, exhibiting good compatibility and high sustainability. Attached Figure Description

[0017] Exemplary embodiments of the present invention can be more fully understood by referring to the following figures: Figure 1 This is a flowchart illustrating the continuous segmented extraction process of perfluorinated compounds provided in an embodiment of the present invention. Detailed Implementation

[0018] To make the technical problems to be solved, the technical solutions, and the beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.

[0019] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention.

[0020] This invention provides a method for fertilizing paddy soil based on the immobilization effect of perfluorinated compounds. The method involves investigating the background levels of perfluorinated compound pollution in paddy soil, determining the types of pollutants involved in the background pollution, evaluating the immobilization effect of several fertilizers on perfluorinated compounds in paddy soil based on the pollutant types, and selecting a fertilization scheme based on the evaluation results of the perfluorinated compound immobilization effect. The pollutant types include ultra-short-chain, short-chain, or long-chain perfluorinated compounds.

[0021] In some embodiments, the effects of several fertilizers on the immobilization of perfluorinated compounds in paddy soil are evaluated, specifically including the following steps: Several fertilizers were added to paddy field soil at a mass percentage of 5% of the perfluorinated compound contaminated soil, and mixed thoroughly. A blank control group without fertilizer was set up. After 14 days, deionized water was added. Several paddy field soil samples were collected on the 21st day after the addition of deionized water. Based on the quantitative values ​​of perfluorinated compound immobilization effects from several paddy field soil samples, the average perfluorinated compound immobilization effects of ultra-short chain, short chain, or long chain perfluorinated compounds in the background pollution of perfluorinated compounds were statistically analyzed, and the evaluation results of the immobilization effects of several fertilizers on perfluorinated compounds in paddy field soil were obtained.

[0022] In some embodiments, the method for obtaining a quantitative value of the immobilization effect of perfluorinated compounds is as follows: Perfluorinated compounds in paddy soil contaminated with perfluorinated compounds are continuously extracted in segments to obtain several forms of perfluorinated compounds, namely, overlying water, soil interstitial water, microbially adsorbed state, cationic bound state, and stable bound state; the concentrations of perfluorinated compounds in several forms are detected, and the ratio of the concentration of perfluorinated compounds in the stable bound state to the total concentration of perfluorinated compounds in several forms is calculated to obtain a quantitative value of the immobilization effect of perfluorinated compounds in paddy soil contaminated with perfluorinated compounds.

[0023] In some embodiments, several types of fertilizers include ammonium chloride, potassium nitrate, urea, chicken manure, sheep manure, earthworm castings, corn straw biochar, rice straw biochar, and wheat straw biochar.

[0024] In some embodiments, the ultrashort-chain perfluorinated compounds include trifluoroacetic acid / perfluoroacetic acid (TFA) and pentafluoropropionic acid / perfluoropropionic acid (PFPrA); Short-chain perfluorinated compounds include perfluorobutyric acid (PFBA), perfluorovalerate (PFPeA), perfluorohexanoic acid (PFHxA), perfluoroheptanoic acid (PFHpA), perfluorobutane sulfonic acid (PFBS), perfluorohexane sulfonic acid (PFHxS), and hexafluoropropylene oxide dimer acid (HFPO-DA). Long-chain perfluorinated compounds include perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDA), perfluoroundecanoic acid (PFUnDA), perfluorododecanic acid (PFDoA), perfluorotetradecanoic acid (PFTeDA), hexafluoropropylene oxide trimeric acid (HFPO-DA), chromium mist inhibitor (F-53B), and sodium perfluorononenoxybenzenesulfonate (OBS).

[0025] In some embodiments, the paddy soil is paddy soil from a fallow period.

[0026] In some embodiments, a continuous, segmented extraction of perfluorinated compounds from paddy soil contaminated with perfluorinated compounds is performed, specifically including the following steps: The overlying water body is collected to detect the concentration of perfluorinated compounds in the overlying water body, and then the overlying water body is discharged to obtain freshly precipitated paddy soil. Weigh paddy soil, add deionized water, mix thoroughly and shake, then vortex to obtain the first water-soil mixed suspension. After sonication of the first water-soil mixed suspension, centrifuge to obtain the first soil precipitate and the first supernatant. The first supernatant is used to detect the perfluorinated compound concentration of perfluorinated compounds in soil pore water. Physiological saline was added to the first soil precipitate, and after thorough mixing and shaking, the mixture was vortexed to obtain the second water-soil mixed suspension. The second water-soil mixed suspension was heated at 70°C and sonicated, and then centrifuged to obtain the second soil precipitate and the second supernatant. The second supernatant was used to detect the concentration of perfluorinated compounds in the microbial adsorbed state. A cationic strong electrolyte solution was added to the second soil precipitate, and the mixture was thoroughly mixed and shaken. The mixture was then vortexed to obtain a third water-soil mixed suspension. The third water-soil mixed suspension was sonicated and centrifuged to obtain a third soil precipitate and a third supernatant. The third supernatant was used to detect the concentration of perfluorinated compounds in cationic bound state. Methanol was added to the third soil precipitate, and after thorough mixing and shaking, the mixture was vortexed to obtain the fourth water-soil mixed suspension. The fourth water-soil mixed suspension was heated at 60°C and sonicated, then centrifuged to obtain the fourth soil precipitate and the fourth supernatant. The fourth supernatant was used to detect the concentration of perfluorinated compounds in a stable bound state.

[0027] In some embodiments, 15 grams of paddy soil are weighed and 10 ml of deionized water is added; 10 ml of physiological saline is added to the first soil precipitate; 10 ml of a 0.01 mol / L cationic strong electrolyte solution is added to the second soil precipitate; and 10 ml of methanol is added to the third soil precipitate.

[0028] In some embodiments, the cationic strong electrolyte solution is a mixture of magnesium chloride and calcium chloride in equal proportions.

[0029] In some embodiments, the weight gain program is specifically as follows: When the main pollutant type in the background pollution of perfluorinated compounds is ultrashort-chain perfluorinated compounds, the recommended fertilization program for paddy field soil is ammonium chloride. When the main pollutant type of background pollution is short-chain or long-chain perfluorinated compounds, the soil fertilization program for paddy fields should be wheat straw biochar.

[0030] Example 1: (1) Collect paddy soil contaminated with 19 perfluorinated compounds (during fallow period). The 19 perfluorinated compounds are: ultra-short chain perfluorinated compounds: trifluoroacetic acid / perfluoroacetic acid TFA, pentafluoropropionic acid / perfluoropropionic acid PFPrA; short chain perfluorinated compounds: perfluorobutyric acid PFBA, perfluorovalerate PFPeA, perfluorohexanoic acid PFHxA, perfluoroheptanoic acid PFHpA, perfluorobutane sulfonic acid PFBS, perfluorohexane sulfonic acid PFHxS and hexafluoropropylene oxide dimer acid HFPO-DA; long chain perfluorinated compounds: perfluorooctanoic acid PFOA, perfluorononanoic acid PFNA, perfluorodecanoic acid PFDA, perfluoroundecanoic acid PFUnDA, perfluorododecanoic acid PFDoA, perfluorotetradecanoic acid PFTeDA, hexafluoropropylene oxide trimer acid HFPO-DA, chromium mist inhibitor F-53B and perfluorononenoxybenzenesulfonate sodium OBS.

[0031] (2) Nine kinds of fertilizers (ammonium chloride, potassium nitrate, urea, chicken manure, sheep manure, earthworm castings, corn straw biochar, rice straw biochar and wheat straw biochar) were added to the paddy field soil contaminated with perfluorinated compounds at a mass percentage of 2% of the soil. They were thoroughly mixed and a blank control group without fertilizer was set up. After 14 days, deionized water was added to simulate irrigation water disturbance. Several paddy field soil samples (a total of 171 samples) were collected on the 21st day after adding deionized water.

[0032] (3) Continuous segmented extraction of perfluorinated compounds from several paddy field soil samples was carried out, specifically including the following steps: The overlying water was collected to detect the concentration of perfluorinated compounds (PFOCs) in the overlying water. The overlying water was then discharged to obtain freshly precipitated paddy soil. 15 grams of paddy soil were weighed into a 50 ml polypropylene centrifuge tube, 10 ml of deionized water was added, the tube was capped, and the mixture was thoroughly mixed and vortexed for 1 minute to obtain a first water-soil suspension. The first water-soil suspension was placed in an ultrasonic cleaner and sonicated at 25°C and 20 kHz for 30 minutes. Then, it was centrifuged at 25°C and 5000 rpm for 10 minutes to separate the solid and liquid, obtaining a first soil precipitate and a first supernatant. The first supernatant was used to detect the PFOC concentration in the soil interstitial water. 10 ml of physiological saline was added to the first soil precipitate, and the mixture was thoroughly mixed and shaken. The mixture was then vortexed to obtain a second water-soil mixed suspension. The second water-soil mixed suspension was placed in an ultrasonic cleaner, heated at 70°C, and sonicated at 100 kHz for 30 minutes. After that, it was centrifuged at 11,000 rpm for 30 minutes to separate the solid and liquid phases and obtain the second soil precipitate and the second supernatant. The second supernatant was used to detect the concentration of perfluorinated compounds in the microbial adsorbed state. 10 mL of a 0.01 mol / L magnesium chloride-calcium chloride mixture was added to the second soil precipitate. The mixture was capped, shaken thoroughly, and mixed in a vortex mixer for 1 minute to obtain a third water-soil mixed suspension. The third water-soil mixed suspension was placed in an ultrasonic cleaner and sonicated at 25°C and 20 kHz for 30 minutes. Then, it was centrifuged at 25°C and 5000 rpm for 10 minutes to separate the solid and liquid phases, resulting in the third soil precipitate and the third supernatant. The third supernatant was used to detect the concentration of perfluorinated compounds in the cation-bound state. 10 mL of HPLC-grade methanol was added to the third soil precipitate, the lid was closed, the mixture was shaken thoroughly and vortexed for 1 minute to obtain the fourth water-soil mixed suspension. The fourth water-soil mixed suspension was placed in an ultrasonic cleaner, heated at 60°C and sonicated at 100 kHz for 30 minutes, and then centrifuged at 5000 rpm for 30 minutes to separate the solid and liquid phases and obtain the fourth soil precipitate and the fourth supernatant. The fourth supernatant was used to detect the concentration of perfluorinated compounds in the stable bound state.

[0033] (4) The concentrations of perfluorinated compounds in overlying water, soil interstitial water, cation-bound, microbial adsorbed and stable-bound forms of perfluorinated compounds in several paddy soil samples were measured respectively. The total perfluorinated compound concentration of several forms of perfluorinated compounds was obtained by summing them. The ratio of the perfluorinated compound concentration of stable-bound perfluorinated compounds to the total perfluorinated compound concentration of several forms of perfluorinated compounds was calculated. This yielded the quantitative value of the immobilization effect of perfluorinated compounds in 171 paddy soil samples contaminated with perfluorinated compounds.

[0034] (5) The 171 paddy soil samples were classified according to the type of pollutants, namely, paddy soil samples contaminated with ultra-short chain, short chain or long chain perfluorinated compounds. The average value of the immobilization effect of paddy soil samples contaminated with ultra-short chain, short chain or long chain perfluorinated compounds was calculated. The immobilization effect value of perfluorinated compounds in the blank control group was subtracted to obtain the evaluation results of the immobilization effect of paddy soil samples contaminated with ultra-short chain, short chain or long chain perfluorinated compounds under the application of 9 kinds of fertilizers.

[0035] The evaluation results of the immobilization effect in paddy field soil samples under the application of nine fertilizers are shown in Table 1. The results show that when the main pollutant type of perfluorinated compounds is ultra-short-chain perfluorinated compounds, ammonium chloride has the highest immobilization improvement rate; when the main pollutant type of perfluorinated compounds is short-chain or long-chain perfluorinated compounds, wheat straw biochar has the highest immobilization improvement rate; when the main pollutant type of perfluorinated compounds is ultra-short-chain, short-chain, and long-chain perfluorinated compounds, wheat straw biochar has the highest immobilization improvement rate.

[0036] Table 1. Increase in PFAS immobilization rate (%) of fertilizer in paddy field soil

[0037] Example 2: We collected paddy field soil (fallow period) contaminated with perfluorinated compounds to conduct a baseline survey of perfluorinated compound pollution in paddy field soil and determined that ultra-short-chain perfluorinated compounds were the main pollutant type in paddy field soil. According to the fertilization method of the present invention, an ammonium chloride fertilization scheme is selected. According to the immobilization effect evaluation method of the present invention, the immobilization improvement rate is calculated to be 2.099%.

[0038] Example 3: Collect perfluorinated paddy soil (fallow period) to investigate the baseline value of perfluorinated paddy soil and determine that short-chain perfluorinated compounds, long-chain perfluorinated compounds, and both short-chain and long-chain perfluorinated compounds are the main pollutants in paddy soil. According to the fertilization method of the present invention, a fertilization scheme using wheat straw biochar is selected. Based on the immobilization effect evaluation method of the present invention, the following calculations are performed: When short-chain perfluorinated compounds were the main pollutants in paddy field soil, the immobilization rate was 10.842%. When long-chain perfluorinated compounds are the main pollutant in paddy field soil, the immobilization rate is 17.016%. When short-chain and long-chain perfluorinated compounds are the main pollutants in paddy field soil, the immobilization rate is 14.473%.

[0039] Example 4: We collected paddy field soils (during fallow period) contaminated with perfluorinated compounds to conduct a baseline survey of perfluorinated compound pollution in the paddy field soils and determine that ultra-short-chain, short-chain, and long-chain perfluorinated compounds were the main pollutant types in the soil. According to the fertilization method of the present invention, wheat straw biochar is selected as the fertilization scheme. According to the immobilization effect evaluation method of the present invention, the immobilization improvement rate is calculated to be 13.043%.

[0040] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for enhancing soil fertility in paddy fields based on the immobilization effect of perfluorinated compounds, characterized in that, A baseline survey of perfluorinated compound (PFC) pollution in paddy soil was conducted to determine the types of PFCs in the baseline pollution. Based on the types of pollutants, the effects of several fertilizers on the immobilization of PFCs in paddy soil were evaluated. Based on the evaluation results of the PFC immobilization effect, a fertilization program was selected. The pollutant types include ultra-short-chain, short-chain, or long-chain perfluorinated compounds.

2. The method for enhancing paddy field soil fertility based on the immobilization effect of perfluorinated compounds as described in claim 1, characterized in that, The evaluation of the effects of several fertilizers on the immobilization of perfluorinated compounds in paddy soil included the following steps: Several fertilizers were added to paddy field soil at a mass percentage of 5% of the perfluorinated compound contaminated soil, and mixed thoroughly. A blank control group without fertilizer was set up. After 14 days, deionized water was added. Several paddy field soil samples were collected on the 21st day after the addition of deionized water. Based on the quantitative values ​​of perfluorinated compound immobilization effects from several paddy field soil samples, the average perfluorinated compound immobilization effects of ultra-short chain, short chain, or long chain perfluorinated compounds in the background pollution of perfluorinated compounds were statistically analyzed, and the evaluation results of the immobilization effects of several fertilizers on perfluorinated compounds in paddy field soil were obtained.

3. The method for enhancing paddy field soil fertility based on the immobilization effect of perfluorinated compounds as described in claim 2, characterized in that, The method for obtaining the quantitative value of the immobilization effect of perfluorinated compounds is as follows: Perfluorinated compounds in paddy soil contaminated with perfluorinated compounds are continuously extracted in segments to obtain several forms of perfluorinated compounds, namely, overlying water, soil interstitial water, microbial adsorbed state, cationic bound state, and stable bound state; the concentration of perfluorinated compounds in several forms is detected, and the ratio of the concentration of perfluorinated compounds in the stable bound state to the total concentration of perfluorinated compounds in several forms is calculated to obtain the quantitative value of the immobilization effect of perfluorinated compounds in paddy soil contaminated with perfluorinated compounds.

4. The method for enhancing paddy field soil fertility based on the immobilization effect of perfluorinated compounds as described in claim 3, characterized in that, Several types of fertilizers include ammonium chloride, potassium nitrate, urea, chicken manure, sheep manure, earthworm castings, corn straw biochar, rice straw biochar, and wheat straw biochar.

5. The method for enhancing paddy field soil fertility based on the immobilization effect of perfluorinated compounds as described in claim 4, characterized in that, Ultrashort-chain perfluorinated compounds include trifluoroacetic acid / perfluoroacetic acid (TFA) and pentafluoropropionic acid / perfluoropropionic acid (PFPrA); Short-chain perfluorinated compounds include perfluorobutyric acid (PFBA), perfluorovalerate (PFPeA), perfluorohexanoic acid (PFHxA), perfluoroheptanoic acid (PFHpA), perfluorobutane sulfonic acid (PFBS), perfluorohexane sulfonic acid (PFHxS), and hexafluoropropylene oxide dimer acid (HFPO-DA). Long-chain perfluorinated compounds include perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDA), perfluoroundecanoic acid (PFUnDA), perfluorododecanic acid (PFDoA), perfluorotetradecanoic acid (PFTeDA), hexafluoropropylene oxide trimeric acid (HFPO-DA), chromium mist inhibitor (F-53B), and sodium perfluorononenoxybenzenesulfonate (OBS).

6. The method for enhancing paddy field soil fertility based on the immobilization effect of perfluorinated compounds as described in claim 5, characterized in that, The paddy field soil is from paddy fields during the fallow period.

7. The method for enhancing paddy field soil fertility based on the immobilization effect of perfluorinated compounds as described in claim 6, characterized in that, The continuous, segmented extraction of perfluorinated compounds from paddy soil contaminated with perfluorinated compounds includes the following steps: The overlying water body is collected to detect the concentration of perfluorinated compounds in the overlying water body, and then the overlying water body is discharged to obtain freshly precipitated paddy soil. Weigh paddy soil, add deionized water, mix thoroughly and shake, then vortex to obtain the first water-soil mixed suspension. After sonication of the first water-soil mixed suspension, centrifuge to obtain the first soil precipitate and the first supernatant. The first supernatant is used to detect the perfluorinated compound concentration of perfluorinated compounds in soil pore water. Physiological saline was added to the first soil precipitate, and after thorough mixing and shaking, the mixture was vortexed to obtain the second water-soil mixed suspension. The second water-soil mixed suspension was heated at 70°C and sonicated, and then centrifuged to obtain the second soil precipitate and the second supernatant. The second supernatant was used to detect the concentration of perfluorinated compounds in the microbial adsorbed state. A cationic strong electrolyte solution was added to the second soil precipitate, and the mixture was thoroughly mixed and shaken. The mixture was then vortexed to obtain a third water-soil mixed suspension. The third water-soil mixed suspension was sonicated and centrifuged to obtain a third soil precipitate and a third supernatant. The third supernatant was used to detect the concentration of perfluorinated compounds in cationic bound state. Methanol was added to the third soil precipitate, and after thorough mixing and shaking, the mixture was vortexed to obtain the fourth water-soil mixed suspension. The fourth water-soil mixed suspension was heated at 60°C and sonicated, then centrifuged to obtain the fourth soil precipitate and the fourth supernatant. The fourth supernatant was used to detect the concentration of perfluorinated compounds in a stable bound state.

8. The method for enhancing paddy field soil fertility based on the immobilization effect of perfluorinated compounds as described in claim 7, characterized in that, Weigh 15 grams of paddy field soil and add 10 ml of deionized water; add 10 ml of physiological saline to the first soil precipitate; add 10 ml of 0.01 mol / L cationic strong electrolyte solution to the second soil precipitate; and add 10 ml of methanol to the third soil precipitate.

9. A method for enhancing paddy field soil fertility based on the immobilization effect of perfluorinated compounds as described in claim 8, characterized in that, The cationic strong electrolyte solution is a mixture of magnesium chloride and calcium chloride in equal proportions.

10. A method for enhancing paddy field soil fertility based on the immobilization effect of perfluorinated compounds as described in claim 1, characterized in that, The specific weight gain plan is as follows: When the main pollutant type in the background pollution of perfluorinated compounds is ultrashort-chain perfluorinated compounds, the recommended soil fertilization program for paddy fields is ammonium chloride. When the main pollutant type of background pollution is short-chain or long-chain perfluorinated compounds, the soil fertilization program for paddy fields should be wheat straw biochar.

Images