A method for inhibiting the denitrification degradation of petroleum hydrocarbon in wetland soil by flavonoid antioxidants

Abstract

This invention provides a method for inhibiting the denitrification degradation of petroleum hydrocarbons in wetland soil using flavonoid antioxidants, specifically relating to the field of soil organic matter degradation technology. The method includes: mixing petroleum hydrocarbon-contaminated wetland soil with flavonoid antioxidants and allowing the mixture to stand; the mass of the flavonoid antioxidants is 0.1-10% of the mass of the petroleum hydrocarbons. The method is simple and easy to operate, requires no large equipment, uses simple reagents, has a fast processing speed, and exhibits significant effects. The use of flavonoid antioxidants is environmentally friendly; they interact with enzymes or other organic compounds produced by bacteria in the soil, altering the chemical balance in the soil microenvironment and inhibiting key steps in the denitrification process, thereby suppressing the degradation of petroleum hydrocarbons in wetland soil. By controlling the amount of flavonoid antioxidants used, the degradation rate of petroleum hydrocarbons can be precisely controlled.

Description

Technical Field

[0001] This invention belongs to the field of soil organic matter degradation technology, specifically relating to a method for inhibiting the denitrification degradation of petroleum hydrocarbons in wetland soils using flavonoid antioxidants. Background Technology

[0002] Wetlands possess vital ecosystem functions such as pollutant purification and self-recovery. They are widely distributed along the southeastern coast of China and play a crucial role in protecting inland areas from typhoons and tsunamis, as well as in biogeochemical cycles. However, coastal wetlands face oil pollution problems due to activities such as oil drilling, refining, and transportation. The transport and accumulation of petroleum hydrocarbons (PH) in coastal wetlands has caused severe damage to the ecosystem.

[0003] The degradation process of organic pollutants in wetlands has attracted much attention. Unlike drylands, the degradation of organic pollutants in flooded wetlands is an anaerobic process, requiring the presence of oxide ions as terminal electron acceptors. Especially for wetlands in estuarine areas, the introduction of large amounts of nitrates due to upstream river flow is significant. Denitrifying bacteria use nitrates as terminal electron acceptors to degrade organic carbon under anaerobic conditions. However, during the rapid degradation of petroleum hydrocarbons, microbial activity becomes abnormally vigorous, consuming large amounts of soil organic matter, altering soil physical properties, destroying soil aggregate structure, making the soil loose, and changing its aeration and permeability. This affects the soil's water and fertilizer retention capacity and the normal growth of wetland plants. Furthermore, intermediate products are generated during petroleum hydrocarbon degradation, which, if not further transformed, accumulate in the environment, causing secondary pollution, disrupting the aquatic ecological balance, and leading to reduced biodiversity. Therefore, effectively controlling the degradation rate of petroleum hydrocarbons in wetland soils has become a key research focus. Summary of the Invention

[0004] In view of this, the purpose of this invention is to provide a method for inhibiting the denitrification degradation of petroleum hydrocarbons in wetland soils using flavonoid antioxidants. The method provided by this invention can effectively control the degradation rate of petroleum hydrocarbons in wetland soils, thereby optimizing the remediation technology for petroleum hydrocarbon-contaminated wetlands.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0006] This invention provides a method for inhibiting the denitrification degradation of petroleum hydrocarbons in wetland soils using flavonoid antioxidants, comprising the following steps:

[0007] Mix petroleum hydrocarbon-contaminated wetland soil with flavonoid antioxidants and let stand;

[0008] The mass of the flavonoid antioxidants is 0.1% to 10% of the mass of petroleum hydrocarbons.

[0009] Preferably, the flavonoid antioxidants include one or more of flavonoids, anthocyanins, flavanones, flavan-3-ols, flavonols, and isoflavones.

[0010] Preferably, the flavonols include at least one of rutin, neohesperidin, and quercetin-3-O-rutin.

[0011] The flavonoids include quercetin and / or kaempferol;

[0012] The dihydroflavonoids include dihydroquercetin;

[0013] The dihydroflavonols include dihydrokaempferol;

[0014] The isoflavones include soy isoflavones;

[0015] The anthocyanins include geranium pigments;

[0016] The flavan-3-ol includes catechins.

[0017] Preferably, the equivalent antioxidant activity of the flavonoid antioxidant is 0.9–3.0 mM.

[0018] Preferably, when the flavonoid antioxidant is rutin, the equivalent antioxidant activity of the flavonoid antioxidant is 2.0 to 3.0 mM;

[0019] When the flavonoid antioxidant is neohesperidin, the equivalent antioxidant activity of the flavonoid antioxidant is 0.9–1.5 mM.

[0020] Preferably, the mass concentration of petroleum hydrocarbons in the petroleum hydrocarbon-contaminated wetland soil is >0.5%.

[0021] Preferably, the settling temperature is 20-25°C and the settling time is 30-40 days.

[0022] Preferably, the wetland soil includes mangrove wetland soil, reed wetland soil, or short-leaved dwarf ...

[0023] Preferably, the moisture content of the petroleum hydrocarbon-contaminated wetland soil is 35-45%;

[0024] The oxygen content in the petroleum hydrocarbon-contaminated wetland soil is <8%.

[0025] Preferably, the petroleum hydrocarbons include straight-chain hydrocarbons and / or aromatic hydrocarbons.

[0026] This invention provides a method for inhibiting the denitrification degradation of petroleum hydrocarbons in wetland soil using flavonoid antioxidants, comprising the following steps: mixing petroleum hydrocarbon-contaminated wetland soil with flavonoid antioxidants and allowing the mixture to stand; wherein the mass of the flavonoid antioxidants is 0.1-10% of the mass of the petroleum hydrocarbons. This invention utilizes flavonoid antioxidants, which are naturally produced by plants and are environmentally friendly. These antioxidants interact with enzymes or other organic compounds produced by bacteria in the soil, altering the chemical balance in the soil microenvironment and inhibiting key steps in the denitrification process. This inhibits the degradation of petroleum hydrocarbons in wetland soil, avoiding the negative impacts of excessive petroleum hydrocarbon degradation on the wetland ecosystem and contributing to the maintenance of wetland ecosystem stability. By controlling the amount of flavonoid antioxidants used, the degradation rate of petroleum hydrocarbons can be precisely controlled.

[0027] This invention, through analysis of test results, reveals that flavonoid antioxidants inhibit microbial activity, primarily through: 1) Damage to microbial cell structure: Polyphenols in plant antioxidants can damage the cell walls and cell membranes of microorganisms, increasing cell membrane permeability and leading to cytoplasmic leakage, thereby inhibiting microbial growth. 2) Chelation of metal ions: Many microorganisms depend on metal ions such as iron for growth; plant antioxidants can inhibit microbial metabolic processes by chelating these metal ions. 3) Inhibition of microbial enzyme activity: Plant antioxidants can inhibit the activity of microbial oxidases, thereby reducing the generation of free radicals and affecting the normal physiological functions of microorganisms. 4) Oxidative stress: Under certain conditions, plant antioxidants can generate reactive oxygen species (ROS), which can cause oxidative damage to microbial cells, destroying their DNA, proteins, and lipids. 5) Synergistic effect: Plant antioxidants can also synergistically act with other antibacterial substances to enhance antibacterial effects. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 The effects of rutin and neohesperidin on the degradation rate of petroleum hydrocarbons in soil containing *Isodon brevifolia*.

[0030] Figure 2 The effects of rutin and neohesperidin on the degradation rate of petroleum hydrocarbons in mangrove soils;

[0031] Figure 3 The effects of rutin and neohesperidin on the degradation rate of petroleum hydrocarbons in reed soil;

[0032] Figure 4The effects of rutin and neohesperidin on the activity of nitrite reductase (NiR) in soil;

[0033] Figure 5 The effects of rutin and neohesperidin on the activity of nitrous oxide reductase (N2OR) in soil;

[0034] Figure 6 The effects of rutin and neohesperidin on nitric oxide reductase (NOR) activity in soil;

[0035] Figure 7 The effects of rutin and neohesperidin on the relative expression level of the denitrification gene nirK;

[0036] Figure 8 The effects of rutin and neohesperidin on the relative expression level of the denitrification gene nosZ. Detailed Implementation

[0037] This invention provides a method for inhibiting the denitrification degradation of petroleum hydrocarbons in wetland soils using flavonoid antioxidants, comprising the following steps:

[0038] Mix petroleum hydrocarbon-contaminated wetland soil with flavonoid antioxidants and let stand;

[0039] The mass of the flavonoid antioxidants is 0.1% to 10% of the mass of petroleum hydrocarbons.

[0040] Unless otherwise specified, all raw materials and equipment used in this invention are commercially available products well known in the art.

[0041] In this invention, the flavonoid antioxidants preferably include one or more of flavones, flavonols, anthocyanins, dihydroflavones, dihydroflavonols, flavanones, chalcones, flavan-3-ols, dihydroisoflavones, and dihydrochalcones; the flavonols preferably include at least one of rutin, neohesperidin, and quercetin-3-O-rutinoside; the flavones preferably include quercetin and / or kaempferol; the dihydroflavones preferably include dihydroquercetin; the dihydroflavonols preferably include dihydrokaempferol; the isoflavones preferably include soy isoflavones; the anthocyanins preferably include geranium pigments; and the flavan-3-ols preferably include catechins. This invention selects flavonoid antioxidants that are environmentally friendly and can interact with enzymes or other organic compounds produced by bacteria in the soil, thereby altering the chemical balance in the soil microenvironment, inhibiting key steps in the denitrification process, and thus suppressing the degradation of petroleum hydrocarbons in wetland soil. This avoids the negative impact of excessive petroleum hydrocarbon degradation on the wetland ecosystem and helps maintain the stability of the wetland ecosystem.

[0042] In this invention, the equivalent antioxidant activity (i.e., TEAC value) of the flavonoid antioxidant is preferably 0.9 to 3.0 mM. In specific embodiments, the equivalent antioxidant activity of the flavonoid antioxidant can be 0.9 mM, 1.0 mM, 1.2 mM, 1.5 mM, 2.0 mM, 2.5 mM or 3.0 mM.

[0043] In this invention, when the flavonoid antioxidant is rutin, the equivalent antioxidant activity of the flavonoid antioxidant is preferably 2.0–3.0 mM. In specific embodiments, the equivalent antioxidant activity of rutin can be 2.0 mM, 2.2 mM, 2.4 mM, 2.7 mM, 2.8 mM, or 3.0 mM. When the flavonoid antioxidant is preferably neohesperidin, the equivalent antioxidant activity of the flavonoid antioxidant is preferably 0.9–1.5 mM. In specific embodiments, the equivalent antioxidant activity of neohesperidin can be 0.9 mM, 1.0 mM, 1.1 mM, 1.3 mM, 1.4 mM, or 1.5 mM.

[0044] In this invention, the wetland soil preferably includes mangrove wetland soil, reed wetland soil, or *Agrostis breviscapus* wetland soil; the mass concentration of petroleum hydrocarbons in the petroleum hydrocarbon-contaminated wetland soil is preferably >0.5%, more preferably 0.5-15%. In specific embodiments, the mass concentration of petroleum hydrocarbons in the petroleum hydrocarbon-contaminated wetland soil can be 0.5%, 1%, 2%, 5%, 7%, 9%, or 10%. The mass of the petroleum hydrocarbon-contaminated wetland soil is expressed as wet weight, referring to the petroleum hydrocarbon-contaminated wetland soil when it contains water.

[0045] In this invention, the water content of the petroleum hydrocarbon-contaminated wetland soil is preferably 35-45%; the oxygen content of the petroleum hydrocarbon-contaminated wetland soil is preferably <8%.

[0046] In this invention, the petroleum hydrocarbons preferably include straight-chain hydrocarbons and / or aromatic hydrocarbons, and the straight-chain hydrocarbons preferably include those with the general structural formula C. n H 2n+2 The alkane, wherein n = 10 to 26, and in a specific embodiment, n can be 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25 or 26; the aromatic hydrocarbon preferably includes 1,2,3-trimethylbenzene.

[0047] In this invention, the mass of the flavonoid antioxidant is 0.1% to 10% of the mass of petroleum hydrocarbons. In specific embodiments, the mass of the flavonoid antioxidant can be 0.1%, 0.3%, 0.5%, 0.8%, 1%, 3%, 5%, 8%, or 10% of the mass of petroleum hydrocarbons. If the amount of flavonoid antioxidant is too low, it cannot inhibit the degradation of petroleum hydrocarbons; increasing the amount will cause the inhibitory effect of the flavonoid antioxidant on the degradation of petroleum hydrocarbons to disappear.

[0048] In this invention, the preferred method for mixing petroleum hydrocarbon-contaminated wetland soil and flavonoid antioxidants is to add flavonoid antioxidants to petroleum hydrocarbon-contaminated wetland soil and mix the wetland soil and flavonoid antioxidants by turning over the soil.

[0049] In this invention, the preferred settling temperature is 20–25°C. In specific embodiments, the settling temperature can be 20°C, 22°C, or 25°C. The preferred settling time is 30–40 days. In specific embodiments, the settling time can be 30 days, 35 days, or 40 days. Adjustments can be made within an appropriate range of flavonoid antioxidant dosage; increasing the dosage results in a longer settling time.

[0050] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below in conjunction with specific embodiments. The described embodiments are only some embodiments of the present invention, and not all embodiments. Any modifications, equivalent substitutions, improvements, etc., made to the embodiments of the present invention based on the technical essence and general principles of the present invention without creative effort should be within the protection scope of the present invention.

[0051] Example 1

[0052] Soil samples were collected from depths of 0–30 cm in the mangrove wetland (MA), reed wetland (RE), and short-leaved dwarf ...

[0053] 5g of soil sample was placed in a 150mL glass bottle, and ultrapure water was added to make the soil-to-water weight ratio 1:2. High-purity nitrogen gas was introduced into the glass bottle for 20 minutes to remove oxygen. 1mL of rutin with an antioxidant activity (TEAC) of 2.4mM and a concentration of 50ppm (100ppm or 200ppm), 1wt% diesel oil (from China National Petroleum Corporation), and 1mL of 5mM potassium nitrate were added. The bottle was sealed with Vaseline to create an anaerobic environment and incubated at room temperature (22±0.5℃) for 35 days. During the incubation period, 30mL of n-hexane was added on days 0, 1, 2, 5, 10, 15, 20, and 35. The concentration changes of petroleum hydrocarbons (straight-chain hydrocarbons and aromatic hydrocarbons) were analyzed by gas chromatography-mass spectrometry (GC-MS).

[0054] Example 2

[0055] Soil samples were collected from depths of 0–30 cm in the mangrove wetland (MA), reed wetland (RE), and short-leaved dwarf ...

[0056] 5g of soil sample was placed in a 150mL glass bottle, and ultrapure water was added to make the soil-to-water weight ratio 1:2. High-purity nitrogen gas was introduced into the glass bottle for 20min to remove oxygen. Neohesperidin with an antioxidant activity (TEAC) of 1.1mM and a concentration of 50ppm (100ppm or 200ppm) was added, along with diesel oil accounting for 1wt% of the soil content, and 1mL of 5mM potassium nitrate. The sample was incubated at room temperature (22±0.5℃) for 35 days. During the incubation period, 30mL of n-hexane was added on days 0, 1, 2, 5, 10, 15, 20, and 35. After vigorous shaking, petroleum hydrocarbons were extracted from the soil, and the concentration changes of petroleum hydrocarbons (straight-chain hydrocarbons and aromatic hydrocarbons) were analyzed by gas chromatography-mass spectrometry (GC-MS).

[0057] Comparative Example 1

[0058] Soil samples were collected from depths of 0–30 cm in the mangrove wetland (MA), reed wetland (RE), and short-leaved dwarf ...

[0059] 5g of soil sample was placed in a 150mL glass bottle, and ultrapure water was added to make the soil-to-water weight ratio 1:2. High-purity nitrogen gas was introduced into the glass bottle for 20min to remove oxygen. Diesel fuel (1wt% of soil content) and 1mL of 5mM potassium nitrate were added. The bottle was incubated at room temperature (22±0.5℃) for 35 days. During the incubation period, 30mL of n-hexane was added on days 0, 1, 2, 5, 10, 15, 20, and 35. After vigorous shaking, petroleum hydrocarbons were extracted from the soil, and the concentration changes of petroleum hydrocarbons (straight-chain hydrocarbons and aromatic hydrocarbons) were analyzed by gas chromatography-mass spectrometry (GC-MS).

[0060] The changes in petroleum hydrocarbon (straight-chain hydrocarbons and aromatic hydrocarbons) concentrations on day 2, as measured in Examples 1-2 and Comparative Example 1, were summarized to observe the effect of flavonoid antioxidants on the degradation rate of petroleum hydrocarbons. Figures 1-3 .from Figures 1-3 Analysis revealed that, by distinguishing between aliphatic and aromatic hydrocarbons, flavonoid antioxidants exhibited a more significant inhibitory effect on aliphatic hydrocarbons. This is because aromatic hydrocarbons, with their benzene rings, are more difficult for microorganisms to utilize and degrade. In reed wetlands, rutin showed a much higher inhibitory effect than neohesperidin, indicating that the content and type of different flavonoid antioxidants directly affect the degree to which they inhibit the degradation of petroleum hydrocarbons.

[0061] Flavonoid antioxidants against NO3 － The role of reductase

[0062] Place 5g of mangrove wetland (reed wetland or short-leaved dwarf lily wetland) soil in a 150mL glass bottle, purge with high-purity nitrogen for 20min, then add 1mL of 5mM KNO3 and 100μg·L⁻¹. -1 Rutin (neohesperidin) was cultured at room temperature for 10 days. Four typical denitrifying enzymes (nitrate reductase, nitrite reductase, nitric oxide reductase, and nitrous oxide reductase) were extracted from the cultured soil. The enzyme activity of nitrate reductase in the soil before and after incubation was determined using a soil nitrate reductase assay kit.

[0063] Four typical denitrifying enzymes (nitrate reductase, nitrite reductase, nitric oxide reductase, and nitrous oxide reductase) were extracted from the soil. The enzyme activity of nitrate reductase in the soil before culture was measured using a soil nitrate reductase assay kit (Hefei Lier Biotechnology Co., Ltd.) as a control group.

[0064] The specific measurement method involved using a spectrophotometer (Bausch and Lomb, Milton Roy LLC, USA) to measure the absorbance of the enzyme at 540 nm. The enzyme activity of nitrate reductase in the soil before and after cultivation was compared, and the results were as follows: Figures 4-6 As shown.

[0065] from Figures 4-6 As can be seen, both rutin and neohesperidin inhibited nitrite reductase (NiR) activity. For nitrite reductase (N2OR) activity, both rutin and neohesperidin showed inhibitory effects in all tested plants. For nitric oxide reductase (NOR) activity, both rutin and neohesperidin also showed inhibitory effects in all tested plants. Overall, flavonoid antioxidants (rutin and neohesperidin) inhibited the activity of most enzymes in different wetland types to varying degrees, further inhibiting the degradation of petroleum hydrocarbons in wetland soils by inhibiting enzyme activity.

[0066] Analysis shows that the inhibitory effect of flavonoid antioxidants on denitrification is mainly concentrated on NO3. - To NO2 - Processes and NO2 - The process of denitrification involves: 1) inhibiting nitrate reductase activity: the first step in denitrification is the reduction of nitrate to nitrite, which is catalyzed by nitrate reductase; 2) inhibiting nitrite reductase activity: nitrite reductase is the key rate-limiting enzyme in denitrification, which catalyzes the further reduction of nitrite to subsequent products such as nitric oxide; 3) affecting electron transport: denitrification requires electron donors to provide electrons to maintain the reduction reaction of nitrate and nitrite. Flavonoids may interfere with the electron transport chain of denitrifying bacteria, affecting the efficiency of electron transport.

[0067] The role of flavonoid antioxidants in denitrification genes

[0068] Place 5g of mangrove wetland (reed wetland or short-leaved dwarf lily wetland) soil in a 150mL glass bottle, purge with high-purity nitrogen for 20min, then add 1mL of 5mM KNO3 and 100μg·L⁻¹. -1 Rutin (neohesperidin) was cultured at room temperature for 10 days, and denitrification genes (nosZ and nirK) from typical denitrifying bacteria were extracted from the cultured soil.

[0069] Denitrification genes (nosZ and nirK) were extracted from typical denitrifying bacteria in the soil before culture and used as a control group. The relative expression levels of these genes in the samples before and after culture were measured using the Scientific Compass platform. The results are as follows: Figures 7-8 As shown.

[0070] from Figures 7-8 The study revealed that rutin and neohesperidin inhibited the relative expression levels of denitrification genes nosZ and nirK, particularly in *Ligustrum brevis* samples. This inhibition affects the denitrification process, thereby influencing nitrogen cycling and petroleum hydrocarbon degradation in wetland soils. For example, the addition of flavonoid antioxidants significantly reduced the expression level of the nirK gene in the soil, affecting the conversion to N2O and consequently the entire denitrification process. In *Ligustrum brevis* soil, the control group showed the highest relative expression levels of nosZ and nirK genes, which decreased significantly after treatment with rutin and neohesperidin. In different wetland types (*Ligustrum brevis*, reeds, and mangroves), both rutin and neohesperidin treatments reduced the relative expression levels of denitrification genes (nosZ and nirK). This indicates that these two plant extracts help inhibit the denitrification process.

[0071] The above analysis shows that the effects of flavonoid antioxidants on petroleum hydrocarbons in soil are mainly reflected in the following aspects: 1) Antioxidant effect: Flavonoid antioxidants have strong antioxidant capacity and can scavenge hydroxyl free radicals. This antioxidant effect may affect the degradation of petroleum hydrocarbons because the biodegradation of petroleum hydrocarbons involves oxidation reactions, and flavonoid antioxidants may inhibit these oxidation reactions by scavenging free radicals. 2) Influence on microbial community: The introduction of petroleum hydrocarbons will change the composition of nutrients in the soil and affect microbial activity. The combination of chemical oxidation and biodegradation is an effective technology for removing petroleum hydrocarbons from the soil. By adjusting the content of nutrients in the soil, the structure of the microbial community can be affected, which may in turn affect the biodegradation of petroleum hydrocarbons. For example, flavonoid antioxidants act as signaling molecules in the interaction between plants and microorganisms. They can serve as the initiation signal for legume-rhizobium symbiosis or the signal for establishing arbuscular mycorrhizal symbiosis. These signaling effects may affect the composition and structure of the rhizosphere microbial community. 3) Inhibition of specific enzyme activity: The degradation of petroleum hydrocarbons involves the action of a series of enzymes, and flavonoid antioxidants may inhibit the degradation of petroleum hydrocarbons by inhibiting the activity of these key enzymes. For example, flavonoid antioxidants can inhibit the activity of digestive enzymes by binding to their active sites. After binding to enzymes, flavonoid antioxidants can affect the secondary structure of enzymes and change their conformation. 4) Phytoremediation mechanisms: Plant roots can absorb petroleum hydrocarbons and remove them through metabolism or endophytic bacteria. Changes in plant root exudates and rhizosphere microbial communities play a key role in the degradation of petroleum hydrocarbons. Flavonoid antioxidants may participate in the mechanism of phytoremediation of petroleum hydrocarbon-contaminated soil by affecting the activity of plant root exudates and rhizosphere microorganisms.

[0072] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for inhibiting the denitrification degradation of petroleum hydrocarbons in wetland soils using flavonoid antioxidants, characterized in that, Includes the following steps: Mix petroleum hydrocarbon-contaminated wetland soil with flavonoid antioxidants and let stand; The mass of the flavonoid antioxidants is 0.1-10% of the mass of petroleum hydrocarbons; The flavonoid antioxidants are rutin or neohesperidin; When the flavonoid antioxidant is rutin, the equivalent antioxidant activity of the flavonoid antioxidant is 2.0~3.0 mM; When the flavonoid antioxidant is neohesperidin, the equivalent antioxidant activity of the flavonoid antioxidant is 0.9~1.5mM; The mass concentration of petroleum hydrocarbons in the petroleum hydrocarbon-contaminated wetland soil is >0.5%; The wetland soils include mangrove wetland soils, reed wetland soils, or short-leaved dwarf ... The petroleum hydrocarbons include straight-chain hydrocarbons and / or aromatic hydrocarbons; The straight-chain hydrocarbon includes those with the general structural formula C1. n H 2n+2 The alkane, wherein n = 10 to 26; the aromatic hydrocarbon includes 1,2,3-trimethylbenzene.

2. The method according to claim 1, characterized in that, The settling temperature is 20~25℃, and the time is 30~40 days.

3. The method according to claim 1, characterized in that, The moisture content of the petroleum hydrocarbon-contaminated wetland soil is 35-45%. The oxygen content in the petroleum hydrocarbon-contaminated wetland soil is <8%.

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