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CN-121405263-B - Coastal wetland nitrogen-reducing carbon-fixing emission-reducing method based on iron circulation

CN121405263BCN 121405263 BCN121405263 BCN 121405263BCN-121405263-B

Abstract

The invention relates to the technical field of wetland ecological restoration, in particular to a coastal wetland nitrogen-reducing carbon-fixing emission-reducing method based on iron circulation. The method comprises the steps of mixing a biochar raw material with water, performing hydrothermal reaction to obtain a biochar precursor, immersing the biochar precursor in a tannic acid modification solution for modification to obtain a modified biochar precursor, and performing pyrolysis on the modified biomass precursor under the conditions of ferrocene vapor and inert atmosphere to obtain the modified biochar. According to the invention, enteromorpha and spartina alterniflora are utilized to prepare the biochar, nitrogen and carbon fixation and emission reduction of the coastal wetland are realized based on iron circulation, and the total nitrogen and greenhouse gas emission of the coastal wetland soil after the modified biochar is added is reduced compared with that of the control group soil, so that the total carbon content is improved.

Inventors

  • HE SHENGBING
  • Ding Shaoxuan
  • PENG YUANJUN
  • SUN SHANSHAN
  • SHAO YANRAN

Assignees

  • 上海交通大学

Dates

Publication Date
20260508
Application Date
20251113

Claims (8)

  1. 1. The preparation method of the modified biochar is characterized by comprising the following steps of: (1) Mixing a biochar raw material with water, and performing hydrothermal reaction to obtain a biochar precursor; (2) Immersing the biochar precursor in tannic acid solution for modification to obtain a modified biochar precursor; (3) Pyrolyzing a modified biochar precursor under the conditions of ferrocene vapor and inert atmosphere to obtain modified biochar; The biochar raw material comprises one or more of enteromorpha, spartina alterniflora and barnacles.
  2. 2. The preparation method of claim 1, wherein when the biochar raw material is a mixture of enteromorpha and spartina alterniflora, the mass ratio of enteromorpha to spartina alterniflora is 1:1.5-2, and when the biochar raw material is a mixture of enteromorpha, spartina alterniflora and barnacle, the mass ratio of enteromorpha, spartina alterniflora and barnacle is 1:1.5-2:1.
  3. 3. The preparation method of the carbon dioxide, according to claim 1, is characterized in that the dosage ratio of the biochar raw material to water is 100-200 g:1-2L, the hydrothermal reaction temperature is 150-180 ℃ and the time is 1-1.5 h.
  4. 4. The preparation method of the tannic acid solution is characterized in that the concentration of the tannic acid solution is 5g/L, the modification method is ultrasonic after oscillation, the oscillation speed is 120-160 rpm, the time is 2-4 h, the frequency of the ultrasonic is 40-50 KHz, the power is 50-60W, the temperature is 25-30 ℃, and the time is 1-2 h.
  5. 5. The preparation method of the ferrocene vapor according to claim 1, which is characterized in that the preparation method of the ferrocene vapor comprises the steps of heating ferrocene under nitrogen atmosphere, and continuously introducing nitrogen to sublimate the ferrocene vapor; The mass ratio of the ferrocene to the modified biochar precursor is 1:20-30, the heating rate of heating is 5-10 ℃ per minute, the temperature is 230-250 ℃, the time is 4-6 h, and the nitrogen gas introducing rate is 0.6-0.8L per minute.
  6. 6. The method according to claim 1, wherein the pyrolysis is carried out at a temperature rise rate of 3-5 ℃ per minute, a temperature of 350-375 ℃ and a time of 3-4 hours.
  7. 7. A modified biochar prepared by the preparation method of any one of claims 1 to 6.
  8. 8. The method for reducing nitrogen, fixing carbon and reducing emission of the coastal wetland based on iron circulation is characterized in that the modified biochar in claim 7 is added into coastal wetland soil affected by tides to reduce nitrogen, fix carbon and reduce emission.

Description

Coastal wetland nitrogen-reducing carbon-fixing emission-reducing method based on iron circulation Technical Field The invention relates to the technical field of wetland ecological restoration, in particular to a coastal wetland nitrogen-reducing carbon-fixing emission-reducing method based on iron circulation. Background The coastal wetland serves as a key ecosystem for sea-land interleaving and plays an important role of a buffer in the global carbon-nitrogen cycle. The deposition environment effectively fixes organic carbon through an anaerobic process, and can reduce nitrogen load through denitrification and other processes, thereby having important significance for relieving global climate change and water eutrophication. Notably, the coastal wetland also has stronger iron reduction and enrichment capability due to sufficient iron sources and ideal 'oxidation barrier' interception conditions. The microorganism and oxygen together mediate iron oxidation reduction and carbon nitrogen migration and conversion to be closely coupled. In an anaerobic environment at high tide, the iron-dissimilatory reducing bacteria convert unstable soluble organic matters into self-stable organic matters by using ferric iron oxide as an electron acceptor, and the process drives the organic matters to mineralize and accumulate microbial biomass carbon. The process couples the iron autotrophic denitrification process by releasing ferrous iron and inhibits nitrous oxide production in the incomplete nitrate reduction process. At the same time, the electron competition effect of the bottom layer influences the methanogenesis process. The ferrous iron diffuses along with tide, is utilized by iron oxidizing bacteria in the reduction layer or is provided with sufficient oxygen supply in the oxidation layer, thereby promoting the combination protection of iron mineral regeneration and organic carbon. However, coastal wetlands face a dual threat of climate change and human activity. The ecological functions of iron mediation are seriously weakened by the rising of sea level, eutrophication of water body and the interference of coastal engineering, namely, the chemical stability of iron minerals is enhanced by oxidizing conditions, so that the coupling of the iron minerals with nitrogen circulation is destroyed by inhibiting denitrification and denitrification efficiency, and meanwhile, the activity of the iron minerals is reduced by long-term exposure, and the complexing protection of organic matters and the inhibition effect on greenhouse gas emission are weakened. Therefore, a new method is needed to overcome the defects of insufficient storage, large engineering quantity, high cost, small repair space area, single repair target and the like of the conventional coastal wetland substrate improvement technology. Disclosure of Invention The invention aims to provide a method for reducing nitrogen, fixing carbon and reducing emission of a coastal wetland based on iron circulation, which aims to solve the problems of excessive accumulation of nitrogen and reduced carbon sink function of the coastal wetland. In order to achieve the above object, the present invention provides the following technical solutions: the invention provides a preparation method of modified biochar, which comprises the following steps: (1) Mixing a biochar raw material with water, and performing hydrothermal reaction to obtain a biochar precursor; (2) Immersing the biochar precursor in tannic acid solution for modification to obtain a modified biochar precursor; (3) Pyrolyzing the modified biomass precursor under the conditions of ferrocene vapor and inert atmosphere to obtain modified biochar; The biochar raw material comprises one or more of enteromorpha, spartina alterniflora and barnacles. Optionally, when the biochar raw material is a mixture of enteromorpha and spartina alterniflora, the mass ratio of enteromorpha to spartina alterniflora is 1:1.5-2, and when the biochar raw material is a mixture of enteromorpha, spartina alterniflora and barnacle, the mass ratio of enteromorpha, spartina alterniflora and barnacle is 1:1.5-2:1. Optionally, the dosage ratio of the biochar raw material to water is 100-200 g:1-2L, the temperature of the hydrothermal reaction is 150-180 ℃ and the time is 1-1.5 h. Optionally, the concentration of the tannic acid solution is 5g/L, the modification method is ultrasonic after oscillation, the oscillation speed is 120-160 rpm, the time is 2-4 hours, the frequency of the ultrasonic is 40-50 KHz, the power is 50-60W, the temperature is 25-30 ℃, and the time is 1-2 hours. Optionally, the preparation method of the ferrocene vapor comprises heating ferrocene under nitrogen atmosphere, and continuously introducing nitrogen to sublimate the ferrocene vapor; The mass ratio of the ferrocene to the modified biochar precursor is 1:20-30, the heating rate of heating is 5-10 ℃ per minute, the temperature is 230-250 ℃, the time is 4-6 h, and the