A bottom improvement material and a method for reducing greenhouse gas emissions from lake sediments

Abstract

The present invention discloses a bottom improvement material and a method for reducing greenhouse gas emissions from lake sediments. The material is composed of a certain proportion of Akadama and nontronite, and the steps are: 1) Selecting mineral materials Akadama and nontronite as raw materials; 2) Pre-treating Akadama and nontronite; 3) Mixing the pre-treated Akadama and nontronite in a certain proportion to prepare a bottom improvement material; 4) Spreading a certain thickness of the bottom improvement material on the lake bottom; 5) Planting submerged plants, and reducing greenhouse gas emissions from shallow lake sediments through the synergistic effect of bottom improvement and submerged plants. The natural ecological matrix material in the present invention has the characteristics of environmental friendliness, reasonable formula, easy use, and ecological environmental protection. The present invention effectively controls and reduces sediment greenhouse gas emissions through the synergistic effect of bottom improvement and submerged plant restoration, providing a new idea for water ecological restoration projects to help carbon neutrality.

Description

Technical Field

[0001] The present invention belongs to the technical field of ecological restoration of lakes, and more specifically relates to a substrate improvement material. It also relates to a method for synergistically reducing greenhouse gas emissions from shallow lake sediments through substrate improvement and submerged plant restoration, and can be applied to ecological restoration projects of eutrophic lakes. Background Art

[0002] Water ecological restoration technology with submerged plant restoration as the core has developed rapidly in the past two decades. Large-scale water system comprehensive management projects at home and abroad basically regard submerged plants as an important part of ecosystem construction. However, in actual restoration work, due to the superposition of various biological and abiotic stress factors in underwater habitats, the survival of submerged plants is often not stably guaranteed. The lack of submerged plants has led to the gradual decline of the ecological functions of lakes, but the natural and human intervention restoration of submerged plant communities in eutrophic lakes is extremely difficult. Submerged plant restoration is a challenge faced by water ecosystem restoration.

[0003] Shallow lakes are considered hotspots for carbon storage and exchange of greenhouse gases such as carbon dioxide (CO2), nitrous oxide (N2O) and methane (CH4). The exchange of air with water is the main pathway for carbon dioxide flux. In addition to diffusion, methane can also be released by bubbles formed in plants and sediments. At the ecosystem level, carbon dioxide is produced by primary production and respiration of all biological communities. Methane production and oxidation are involved in different microorganisms, mainly produced in anoxic and organic-rich sediments, and oxidized in the sediment-water interface and water column. Ecosystems with a high ratio of primary production to respiration will absorb carbon dioxide if there is no excessive external carbon input. When primary producers are included in the synthesis of biomass and part of the respiration process, methane production is low. When the organic matter sedimentation rate is high, highly anaerobic decomposition processes are accompanied by high methane production and emissions. Rhizosphere oxygenation and water column oxidation generated by primary production of submerged plants can enhance methane oxidation and inhibit its emission to the atmosphere. Greenhouse gases from aquatic ecosystems are mainly emitted to the atmosphere through the sediment-water-atmosphere system. How to restore submerged plants while minimizing sediment greenhouse gas emissions has become an important issue facing the restoration of inland water ecosystems in my country under the "dual carbon" goals.

[0004] The present invention aims to effectively control and reduce greenhouse gas emissions from sediments through the synergistic effect of bottom improvement and submerged plant restoration, providing new ideas for promoting carbon neutrality in water ecological restoration projects. Summary of the invention

[0005] The purpose of the present invention is to solve the problem of how to restore submerged plants while minimizing the emission of greenhouse gases from sediments, and to provide a bottom improvement material with a reasonable formula, easy use, environmental protection and no pollution.

[0006] Another object of the present invention is to provide a method for reducing greenhouse gas emissions from shallow lake sediments through the synergistic effect of bottom improvement materials and submerged plant restoration. The method is easy to implement, simple to operate, low cost, and has significant environmental and economic benefits. The natural ecological matrix material in the present invention is environmentally friendly. The present invention effectively controls and reduces greenhouse gas emissions from sediments through the synergistic effect of bottom improvement and submerged plant restoration, providing a new idea for promoting carbon neutrality in water ecological restoration projects.

[0007] In order to achieve the above-mentioned purpose, the present invention adopts the following technical solutions:

[0008] A bottom improvement material, which is made of the following raw materials in mass fractions:

[0009] raw material%

[0010] Red jade soil 60-90

[0011] Nontronite 10-40.

[0012] A substrate improvement material, which is made of the following raw materials in mass fraction (preferred range):

[0013] raw material%

[0014] Akadama soil 65-90

[0015] Nontronite 10-35.

[0016] A bottom improvement material, which is made of the following raw materials in mass fraction (preferable range):

[0017] raw material%

[0018] Akadama soil 68-85

[0019] Nontronite 15-32.

[0020] A bottom improvement material, which is made of the following raw materials in mass fraction (optimal range):

[0021] raw material%

[0022] Red jade soil 75-82

[0023] Nontronite 18-25.

[0024] A bottom improvement material, which is made of the following raw materials in mass fraction (optimum value):

[0025] raw material%

[0026] Akadama Soil 81

[0027] Nontronite19.

[0028] Akadama is a soil medium with silicon dioxide, aluminum oxide and iron oxide as the main chemical components. It comes from volcanic mud formed by volcanic accumulation in Japan. It has abundant reserves and low prices. The particles are dark red, the surface is rough and porous, and it has high permeability and slight acidity. It has good adsorption capacity for heavy metals, nitrogen and phosphorus, radioactive elements, etc. As one of the clay mineral materials, Akadama has a much larger specific surface area and pore volume than other materials, so it has stronger adsorption potential. The specific surface area of ​​Akadama is 8.54 times, 3.47 times and 12.3 times that of vermiculite, bentonite and zeolite, respectively, and the pore volume is 1.88 times, 5.49 times and 21.10 times that of them, respectively.

[0029] Nontronite is a unique dioctahedral clay mineral in deep-sea sediments. It is usually yellow-green or brown-green in color and is an iron-rich montmorillonite. Nontronite is naturally rich in iron and contains trace amounts of organic matter. It is monoclinic and usually appears as cryptocrystalline earthy and dense block aggregates.

[0030] The applicant has previously conducted relevant research on the improvement of the bottom of eutrophic water bodies, but there are no relevant reports on the improvement of bottom and the reduction of greenhouse gas emissions from sediments by submerged plants. The present invention, through a large number of studies and experimental demonstrations, for the first time mixes the above two materials in a certain proportion to prepare a bottom improvement material, which is applied to the lake sediment repair and restoration project. Of the two materials, the most critical is nontronite, which has a unique dioctahedral structure, is naturally rich in iron, and contains trace organic matter. In the application, it was found that when the Fe(III) in the nontronite mineral structure is reduced, part of the mineral dissolves to release Fe(II) and Al(III), of which part of the released Fe(II) will be re-adsorbed at the edge face sites of the mineral and enter the vacancy of the trans configuration of the octahedral layer, and the released Al(III) can form a new active Al(III)-rich layer on the mineral basal surface after reprecipitation reaction. The different morphological structures and surface Fe(II) and active Al(III) layers formed in the above reaction process significantly improve the interfacial chemical reaction activity of the mineral.

[0031] The ratio of Akadama and Nontronite is the most suitable ratio obtained through a large number of experimental studies and engineering applications. Akadama has a rough and porous surface, high permeability and slight acidity, which improves the sediment microhabitat and provides the necessary trace elements to form a nutrient source for microbial growth, promoting the growth of microorganisms related to the carbon-nitrogen cycle. Therefore, the present invention combines the above two materials in proportion, gives full play to the characteristics and advantages of the two materials, and prepares them into bottom improvement materials. Through the synergistic effect of bottom improvement and submerged plant restoration, it effectively controls and reduces sediment greenhouse gas emissions, providing new ideas for water ecological restoration projects to help carbon neutrality.

[0032] A method for reducing greenhouse gas emissions from shallow lake sediments by synergistic effects of bottom improvement materials and submerged plant restoration, the steps of which are:

[0033] 1) Soak a certain proportion of red jade in 1-5% dilute hydrochloric acid for 1-2 hours, then wash with clean water until neutral and set aside;

[0034] 2) Soak a certain proportion of nontronite in 2-8% dilute hydrochloric acid for 1-2 hours, then wash with clean water until neutral and set aside;

[0035] 3) mixing the pretreated Akadama and nontronite at a certain mass fraction to prepare a bottom improvement material;

[0036] 4) Spread a certain thickness (1.5-3 cm) of the bottom improvement material on the lake bottom;

[0037] 5) Plant submerged plants in the bottom improvement areas to reduce greenhouse gas emissions from shallow lake sediments through the synergistic effect of bottom improvement and submerged plants.

[0038] The submerged plants are one or any combination of two to eight of the following: water chestnut, Vallisneria, Myriophyllum paniculate, Potamogeton malayi, Potamogeton microdentata, Ceratophyllum, Elodea and Hydrilla verticillata. The submerged plant planting method is: wrapping the above-mentioned substrate improvement material with a degradable non-woven fabric to prepare a planting carrier, transplanting the submerged plants into the carrier, and throwing it into the lake bottom from the lake surface, with a planting density of 60 plants (clumps) per square meter.

[0039] Through the above technical measures: the most critical thing is to mix the pretreated Akadama and nontronite evenly according to a certain mass fraction to prepare a bottom improvement material, which mainly solves the technical difficulties of reducing greenhouse gas emissions from shallow lake sediments, and provides a new idea for water ecological restoration projects to help carbon neutrality. Through the entire technical measure, the functional genes involved in the carbon and nitrogen cycles and other processes increased by more than 380%, and the greenhouse gas emissions from sediments were reduced by more than 80%. The existing technology is difficult to effectively inhibit greenhouse gas emissions only through the single technical action of submerged plants. The progress of its invention relative to the existing technology is mainly reflected in the first discovery that mixing Akadama and nontronite to prepare a bottom improvement material can restore submerged plants while minimizing the emission of greenhouse gases from sediments, effectively solving the important problems facing the restoration of China's inland water ecosystems under the "dual carbon" goal.

[0040] Compared with the prior art, the present invention has the following advantages and effects:

[0041] 1. The method is easy to implement, simple to operate, low cost, and has significant environmental and economic benefits;

[0042] 2. The bottom improvement materials are all composed of natural clay minerals, which are environmentally friendly and have no secondary pollution;

[0043] 3. Give full play to the characteristics of natural materials and significantly promote the coating and growth of functional microorganisms.

[0044] 4. The greenhouse gas emissions from shallow lake sediments were significantly reduced through the synergistic effect of bottom improvement and submerged plants. Compared with the control group, the Shannon diversity index of the microbial community increased by more than 60%, the microbial abundance increased by more than 340%, the functional genes involved in carbon and nitrogen cycles increased by more than 380%, and the greenhouse gas emissions from sediments decreased by more than 80%. DETAILED DESCRIPTION

[0045] In order to better understand the present invention, the content of the present invention is further explained below in conjunction with the embodiments, but the content of the present invention is not limited to the following embodiments.

[0046] Embodiment 1:

[0047] A bottom improvement material, which is made of the following raw materials in mass fractions:

[0048] raw material%

[0049] Red jade soil 85

[0050] Nontronite 15.

[0051] A method for reducing greenhouse gas emissions from shallow lake sediments by synergistic effects of bottom improvement materials and submerged plant restoration, the steps of which are:

[0052] 1) Soak the red jade in 1% dilute hydrochloric acid for 1 hour, then wash with clean water until it becomes neutral and set aside;

[0053] 2) Soak the nontronite in 2% dilute hydrochloric acid for 2 hours, then wash with clean water until it becomes neutral and set aside;

[0054] 3) mixing the pretreated Akadama and nontronite at a mass fraction ratio of 9:1 to prepare a bottom improvement material;

[0055] 4) A certain sediment restoration area of ​​West Lake in Hangzhou City, Zhejiang Province was selected to implement the present invention, and the natural ecological matrix material was evenly spread on the lake surface to the bottom, with a spreading thickness of about 2 cm;

[0056] 5) Plant submerged plant Vallisneria in the bottom improvement area to reduce greenhouse gas emissions from shallow lake sediments through the synergistic effect of bottom improvement and submerged plants.

[0057] 6) After 2 months of implementation, compared with the control group, the Shannon diversity index of the microbial community increased by more than 70%, the microbial abundance increased by more than 360%, the functional genes involved in carbon and nitrogen cycles increased by more than 400%, and the greenhouse gas emissions from sediments decreased by more than 85%.

[0058] Embodiment 2:

[0059] A bottom improvement material, which is made of the following raw materials in mass fractions:

[0060] raw material%

[0061] Red jade soil 75

[0062] Nontronite 25.

[0063] A method for reducing greenhouse gas emissions from shallow lake sediments by synergistic effects of bottom improvement materials and submerged plant restoration, the steps of which are:

[0064] 1) Soak the red jade in 2% dilute hydrochloric acid for 1.5 hours, then wash with clean water until it becomes neutral and set aside;

[0065] 2) Soak the nontronite in 3% dilute hydrochloric acid for 1.5 hours, then wash with clean water until neutral and set aside;

[0066] 3) mixing the pretreated Akadama and nontronite at a mass fraction ratio of 8.5:1.5 to prepare a bottom improvement material;

[0067] 4) A sediment restoration area of ​​West Lake in Hangzhou, Zhejiang Province was selected to implement the present invention, and the natural ecological matrix material was evenly spread on the lake surface to the bottom, with a spreading thickness of 1.8 cm;

[0068] 5) Plant submerged plant Vallisneria in the bottom improvement area to reduce greenhouse gas emissions from shallow lake sediments through the synergistic effect of bottom improvement and submerged plants.

[0069] 6) After 2 months of implementation, compared with the control group, the Shannon diversity index of the microbial community increased by more than 75%, the microbial abundance increased by more than 380%, the functional genes involved in carbon and nitrogen cycles increased by more than 430%, and the greenhouse gas emissions from sediments decreased by more than 88%.

[0070] Embodiment 3:

[0071] A bottom improvement material, which is made of the following raw materials in mass fractions:

[0072] raw material%

[0073] Akadama soil 80

[0074] Nontronite 20.

[0075] After two months of implementation, compared with the control group, the Shannon diversity index of the microbial community increased by more than 70%, the microbial abundance increased by more than 365%, the functional genes involved in carbon and nitrogen cycles and other processes increased by more than 410%, and the greenhouse gas emissions from sediments decreased by more than 86%.

[0076] The preparation steps are the same as those of Example 1 or Example 2.

[0077] Embodiment 4:

[0078] A bottom improvement material, which is made of the following raw materials in mass fractions:

[0079] raw material%

[0080] Red jade soil 88

[0081] Nontronite12.

[0082] The preparation steps are the same as those of Example 1 or Example 2.

[0083] After two months of implementation, compared with the control group, the Shannon diversity index of the microbial community increased by more than 65%, the microbial abundance increased by more than 350%, the functional genes involved in carbon and nitrogen cycles increased by more than 380%, and the greenhouse gas emissions from sediments decreased by more than 82%. For the first time, it was found that mixing Akadama and nontronite to prepare a bottom improvement material can restore submerged plants while minimizing greenhouse gas emissions from sediments, effectively solving the important problems facing the restoration of inland water ecosystems in my country under the "dual carbon" goal.

Claims

1. A method for reducing greenhouse gas emissions from lake sediments, characterized in that: The steps are: 1) Soak a certain proportion of red jade in 1-5% dilute hydrochloric acid for 1-2 hours, then wash with clean water until neutral and set aside; 2) Soak a certain proportion of nontronite in 2-8% dilute hydrochloric acid for 1-2 hours, then wash with clean water until neutral and set aside; 3) mixing the pretreated Akadama and nontronite at a certain mass fraction to prepare a bottom improvement material; 4) Spread the bottom improvement material to a thickness of 1.5-3 cm on the lake bottom; 5) Planting submerged plants in the bottom improvement areas to reduce greenhouse gas emissions from shallow lake sediments through the synergistic effect of bottom improvement and submerged plants; The submerged plant planting method comprises: wrapping the bottom improvement material with a degradable non-woven fabric to prepare a planting carrier, transplanting the submerged plants into the carrier, and throwing them into the lake bottom from the lake surface, with a planting density of 60 plants per square meter; The substrate improvement material is made of the following raw materials by mass fraction: raw material% Red jade soil 60-90 Nontronite 10-40.

2. The method according to claim 1, characterized in that The substrate improvement material is made of the following raw materials by mass fraction: raw material% Akadama soil 65-90 Nontronite 10-35.

3. The method according to claim 1, characterized in that The substrate improvement material is made of the following raw materials by mass fraction: raw material% Akadama soil 68-85 Nontronite 15-32.

4. The method according to claim 1, characterized in that: The substrate improvement material is made of the following raw materials by mass fraction: raw material% Red jade soil 75-82 Nontronite 18-25.

5. The method according to claim 1, characterized in that The substrate improvement material is made of the following raw materials by mass fraction: raw material% Akadama Soil 81 Nontronite19.

6. The method according to claim 1, characterized in that: The bottom improvement material is spread on the lake bottom at a depth of 1.5-3 cm.

7. The method according to claim 1, characterized in that: The submerged plants are one of water chestnut, Vallisneria, Myriophyllum paniculate, Potamogeton malayi, Potamogeton microdentata, Ceratophyllum, Elodea and Hydrilla verticillata, or any combination of two to eight of them.