Application method of iron-intercalated montmorillonite in promotion of diatom outbreak in iron-deficient seawater
By preparing and applying iron-intercalated montmorillonite to iron-deficient seawater, the problems of silicate and iron deficiency were solved, promoting the proliferation and carbon fixation capacity of diatoms and achieving stable carbon output enhancement.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-17
- Publication Date
- 2026-03-13
AI Technical Summary
Existing technologies face a dual bottleneck in iron-deficient sea areas: the lack of silicates and iron limits diatom growth and prevents effective enhancement of the carbon output capacity of biopumps.
Iron-intercalated montmorillonite was used as the iron source. Through the preparation process, iron replaced the interlayer cations of montmorillonite to form stable iron-intercalated montmorillonite, which was then applied to iron-deficient seawater to provide a continuous iron source to promote diatom growth.
It significantly enhances the diatom proliferation capacity and primary productivity in iron-deficient seawater, increases the carbon flux exported to the deep sea, improves the carbon fixation capacity of diatoms, and the iron-intercalated montmorillonite is not easily diffused by ocean currents, resulting in a long duration of action.
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Abstract
Description
Technical Field
[0001] This invention relates to the technical field of marine fertilization, and in particular to the application of iron-intercalated montmorillonite in promoting diatom blooms in iron-deficient seawater. Background Technology
[0002] As the largest active carbon sink on Earth, the ocean stores approximately 93% of global carbon dioxide, about 20 times the carbon storage capacity of terrestrial carbon sinks and 50 times that of atmospheric carbon sinks, playing an irreplaceable role in global climate regulation. Ocean carbon sequestration mainly occurs through mechanisms such as biopumps, solubility pumps, carbonate pumps, and microbial carbon pumps. Among these, biopumps are one of the most important carbon sink pathways in the ocean, transporting more than 10 Gt Ca into the deep sea annually. –1 Marine diatoms are crucial for long-term carbon sequestration in the ocean. They are a key group of organisms driving the biological pump, accounting for a huge proportion of phytoplankton in both quantity and variety, and can fix approximately 1 × 10⁻⁶ tons of carbon annually through efficient photosynthesis. 12 kg of carbon dioxide contributes more than 40% of the primary productivity of the global oceans and about 20% of the carbon sequestration, playing a central role in the ocean carbon cycle.
[0003] Based on the important role of diatoms, previous studies have attempted to promote diatom growth by applying liquid iron to iron-deficient sea areas, thereby enhancing the carbon output of the biological pump and mitigating global warming. However, in the large-scale iron fertilization experiments that have been carried out, significant proliferation of diatoms and an increase in carbon output flux were only observed in iron-deficient sea areas with sufficient silicates. This indicates that the existing methods have the following obvious limitations: (1) In some iron-deficient sea areas, there is a problem of simultaneous silicate deficiency. Therefore, even if iron is supplemented, diatom growth is still limited and cannot form a dominant population, resulting in a limited increase in carbon output; (2) After being applied to the ocean, liquid iron is easily diffused and diluted rapidly by ocean currents, making it difficult to maintain an effective concentration and affecting its sustained promoting effect on diatom growth.
[0004] Therefore, there is an urgent need in this field to develop a new method for marine iron fertilization that can overcome the dual bottlenecks of silicate limitation and iron deficiency, thereby stably and efficiently enhancing the carbon sequestration capacity of biopumps in iron-deficient sea areas around the world and providing reliable technical support for addressing climate change. Summary of the Invention
[0005] In view of the shortcomings of the existing technology, the purpose of this invention is to propose a new method for marine iron fertilization that can overcome the dual bottlenecks of silicate limitation and iron deficiency. This method can significantly increase the proliferation capacity of diatoms in iron-deficient seawater, improve their primary productivity and carbon content, and increase their carbon flux output to the deep sea.
[0006] The technical solution of the present invention is as follows: A method for applying iron-intercalated montmorillonite to promote diatom blooms in iron-deficient seawater includes: applying iron-intercalated montmorillonite to iron-deficient seawater containing diatoms, wherein the iron-deficient seawater has an iron concentration of less than 0.3 nM, and the iron-intercalated montmorillonite is obtained through the following process: (1) Add sodium carbonate and / or hydrated sodium carbonate to an aqueous solution of iron salt, mix thoroughly to form a reddish-brown semi-transparent substance, and then age at room temperature to obtain an iron pillar solution; (2) Add montmorillonite to water and heat it to swell, thus obtaining a montmorillonite suspension; (3) The iron-supported liquid is slowly added dropwise to the montmorillonite suspension and heated and mixed. After the addition is completed, the mixture is continued for a certain period of time, and then aged at room temperature. After that, solid-liquid separation, solid drying and grinding are carried out in sequence to obtain the iron-intercalated montmorillonite.
[0007] According to some preferred embodiments of the present invention, the iron salt is selected from ferric nitrate and / or ferric chloride.
[0008] According to some preferred embodiments of the present invention, the montmorillonite is selected from calcium-based montmorillonite and / or sodium-based montmorillonite.
[0009] According to some preferred embodiments of the present invention, the molar ratio of sodium carbonate and / or hydrated sodium carbonate to iron salt in the iron-pillared solution is 0.5-2.5:1, and the pH of the iron-pillared solution is <2.
[0010] According to some preferred embodiments of the present invention, the room temperature aging time is 20-24 hours.
[0011] According to some preferred embodiments of the present invention, the temperature of the heating and swelling is 50-70°C.
[0012] According to some preferred embodiments of the present invention, the heating and swelling time is 1.5-2.5 hours.
[0013] According to some preferred embodiments of the present invention, the temperature of the heating and mixing is 50-70°C.
[0014] According to some preferred embodiments of the present invention, the continued mixing time is 1.5-2.5 hours.
[0015] According to some preferred embodiments of the present invention, the temperature for drying the solid is 40-50°C.
[0016] According to some preferred embodiments of the present invention, the solid-liquid ratio of the montmorillonite suspension is 1:45-55 g / mL.
[0017] According to some preferred embodiments of the present invention, the volume ratio of the iron pillar fluid to the montmorillonite suspension is 1-2:1.
[0018] According to some preferred embodiments of the present invention, the diatom is selected from one or more of the following: seaweed, chamomile, rhomboid algae, small ring algae, and boat-shaped algae.
[0019] According to some preferred embodiments of the present invention, the iron-intercalated montmorillonite is applied at a concentration of 10-50 mg / L in the iron-deficient seawater.
[0020] According to some preferred embodiments of the present invention, the application method includes: (1) Add the iron-intercalated montmorillonite to seawater to prepare an iron-intercalated montmorillonite concentrate with a concentration of 10-50 g / L; (2) The iron-intercalated montmorillonite concentrate is evenly sprayed onto the surface of the iron-deficient seawater using a spraying tool.
[0021] According to some preferred embodiments of the present invention, the spraying rate of the iron-intercalated montmorillonite concentrate is 0.2826 m³ / h. 2 Spray 1L of water into the sea.
[0022] The application method of this invention can promote the proliferation and explosion of iron-deficient diatoms in iron-deficient seawater, whose growth is limited due to iron deficiency, by applying iron-intercalated montmorillonite. By using iron-intercalated montmorillonite as an iron source to cultivate diatoms, the primary productivity and carbon fixation capacity of diatoms are enhanced, increasing the carbon flux exported to the deep sea. This results in a primary productivity of marine diatoms (represented by chlorophyll a content) that is more than 20% higher than that of diatoms cultivated with liquid iron. In the application method of this invention, during the preparation of iron-intercalated montmorillonite, iron can replace the interlayer cations of montmorillonite and exist stably between the montmorillonite layers, enabling it to replace liquid iron as a sufficient and sustainable iron source for diatoms. Simultaneously, during preparation, the montmorillonite undergoes prolonged exposure to strong acid and heating environments, exposing surface active sites and making the silicon in the lamellar structure more readily soluble and usable by diatoms. Practical applications show that when iron-intercalated montmorillonite is applied to iron-deficient diatom culture media instead of liquid iron, diatoms can interact with the iron-intercalated montmorillonite, dissolving bioavailable iron and silicates. This promotes diatom proliferation and increases primary productivity and carbon content. Furthermore, the added iron-intercalated montmorillonite is not easily diffused by ocean currents, and its effect is sustained and long-lasting. Detailed Implementation
[0023] The technical solutions of the present invention will be further described below with reference to embodiments thereof. The embodiments described below are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort should fall within the scope of protection of the present invention.
[0024] The calcium-based montmorillonite used in the following examples was collected from Chifeng, Inner Mongolia.
[0025] Example 1 Iron-intercalated montmorillonite was prepared by the following process: (1) Take 6.2 g of Na2CO3·H2O powder and slowly add it into a 0.2 mol / L ferric nitrate solution. Stir at 1100 r / min for 2 h to form a reddish-brown semi-transparent solution (pH<2). Then, age it at room temperature for 24 h to obtain an iron column solution. (2) Take 10g of calcium-based montmorillonite and add it to 500ml of deionized water. Stir in a 60℃ water bath for 1.5h to allow it to fully swell and form a montmorillonite suspension with a concentration of about 2wt%. (3) Take the iron pillar liquid and slowly add it dropwise to the montmorillonite suspension. Stir at high speed in a 60°C water bath so that the iron displaces the calcium ions in the interlayer and enters the interlayer. After the addition is complete, continue stirring for 2 hours. Then age at room temperature for 20 hours, centrifuge, dry, and grind until it can pass through a 200-mesh sieve to obtain iron-intercalated montmorillonite.
[0026] Example 2 Iron-deficient diatoms were cultured using the following process: (1) Place 2 L of artificial seawater as shown in Table 1 into a high-temperature steam sterilizer and sterilize at 121°C for 30 min, then cool to room temperature to obtain cooled seawater; (2) The nutrient components without FeCl3·6H2O (the composition of which is shown in Table 2) were sterilized under ultraviolet light for 15 min, and then added to cooled seawater to obtain iron-deficient seawater culture medium. (3) Adjust the pH of the iron-deficient seawater culture medium to 8.10, and then add diatom solution with a diatom content of 50-100wt%. The volume ratio of diatom solution to iron-deficient seawater culture medium is 1:9. Culture for 15 days under the following conditions: light intensity of 4000 lux, light cycle of 12 / 12 light-dark cycle (light and darkness are set to alternate for 12 hours each), and temperature of 25℃. Repeat step (3) a total of 3 times to obtain iron-deficient diatom culture medium.
[0027] Table 1. Components and concentrations of artificial seawater
[0028] Table 2. Nutrient components and their concentrations in iron-deficient seawater culture medium
[0029] Example 3 The following process was used to simulate the application of iron-intercalated montmorillonite in promoting diatom blooms in iron-deficient seawater: (1) Add 1g of iron-intercalated montmorillonite obtained in Example 1 to 0.1L of iron-deficient seawater culture medium prepared in Example 2 to obtain a concentrated iron-intercalated montmorillonite solution with a concentration of 10g / L. (2) Under sterile conditions, add 10 ml of the iron-deficient diatom culture medium obtained in Example 2 and 90 ml of the iron-deficient seawater culture medium prepared in Example 2 to a 150 ml culture flask, and adjust the pH of the resulting mixture to 8.10 to obtain a mixed culture medium. (3) Measure 0.1 ml of iron-intercalated montmorillonite concentrate and spray it evenly into the mixed culture medium so that the concentration of iron-intercalated montmorillonite in the mixed culture medium is 10 mg / L. Culture it for 8 days under the conditions of light intensity of 4000 lux, light cycle of 12 / 12 light-dark cycle, and temperature of 25℃ to obtain the simulated solution.
[0030] Example 4 The following process was used to simulate the application of iron-intercalated montmorillonite in promoting diatom blooms in iron-deficient seawater: (1) Add 5g of iron-intercalated montmorillonite obtained in Example 1 to 0.1L of iron-deficient seawater culture medium prepared in Example 2 to obtain a concentrated iron-intercalated montmorillonite solution with a concentration of 50g / L. (2) Under sterile conditions, add 10 ml of the iron-deficient diatom culture medium obtained in Example 2 and 90 ml of the iron-deficient seawater culture medium prepared in Example 2 to a 150 ml culture flask, and adjust the pH of the resulting mixture to 8.10 to obtain a mixed culture medium. (3) Measure 0.1 ml of iron-intercalated montmorillonite concentrate and spray it evenly into the mixed culture medium so that the concentration of iron-intercalated montmorillonite in the mixed culture medium is 50 mg / L. Culture it for 8 days under the conditions of light intensity of 4000 lux, light cycle of 12 / 12 light-dark cycle, and temperature of 25℃ to obtain the simulated solution.
[0031] Comparative Example 1 The following process was used to simulate diatom growth in iron-deficient seawater: (1) Under sterile conditions, 10 ml of iron-deficient diatom culture medium obtained in Example 2 and 90 ml of iron-deficient seawater culture medium prepared in Example 2 were added to a 150 ml culture flask, and the pH of the resulting mixture was adjusted to 8.10 to obtain a mixed culture medium. (2) The mixed culture medium was cultured for 8 days under the conditions of light intensity of 4000 lux, light cycle of 12 / 12 light-dark cycle and temperature of 25℃ to obtain the simulated solution.
[0032] Comparative Example 2 The following process simulates the application of iron salts in promoting diatom blooms in iron-deficient seawater: (1) Under sterile conditions, 10 ml of iron-deficient diatom culture medium obtained in Example 2 and 90 ml of iron-deficient seawater culture medium prepared in Example 2 were added to a 150 ml culture flask, and the pH of the resulting mixture was adjusted to 8.10 to obtain a mixed culture medium. (2) Add 0.1 ml of FeCl3·6H2O aqueous solution with a concentration of 11 mmol / L to the mixed culture medium, and culture for 8 days under the conditions of light intensity of 4000 lux, light cycle of 12 / 12 light-dark cycle and temperature of 25℃ to obtain the simulated solution.
[0033] Tests showed that the number of diatoms in the mixed culture media obtained in Examples 3 and 4, and Comparative Examples 1 and 2, was all <10. 4 The number of diatoms was determined by counting them using a biological microscope.
[0034] Furthermore, the number of diatoms, chlorophyll a concentration, carbon content, and the chlorophyll a concentration increase rate and carbon content increase rate in the simulated solutions obtained in Examples 3 and 4 and Comparative Examples 1 and 2 were measured.
[0035] The number of diatoms was obtained by counting them using a biological microscope.
[0036] The concentration of chlorophyll a was determined using the methanol extraction method, as follows: 20 mL of the simulated solution was measured and filtered through a 0.45 μm glass fiber membrane. The filtered membrane was then extracted with 10 mL of methanol at 4°C. Finally, the absorbance values (OD652 and OD665) at 652 and 665 nm were measured using a UV spectrophotometer, and the concentration of chlorophyll a was determined using the following formula: Chlorophyll-a =-8.0962×OD652 +16.5169×OD665 Wherein, Chlorophyll-a represents the concentration of chlorophyll a, and OD652 and OD665 represent the absorbance values at the absorption peaks of 652 and 665 nm, respectively.
[0037] The carbon content was determined by measuring 20 mL of the simulated solution and filtering it through a 0.45 μm glass fiber membrane. The carbon content of the diatoms was then analyzed using a LECO CS744 analyzer.
[0038] The chlorophyll a concentration increase rate and carbon content increase rate were based on the chlorophyll a concentration and carbon content obtained in Comparative Example 1 (without iron).
[0039] The measurement results are shown in Table 3 below: Table 3. Results of the simulated solutions for the examples and comparative examples.
[0040] As can be seen from the table above, applying a certain concentration of iron-intercalated montmorillonite can promote the growth and flourishing of diatoms, and at the same time enhance diatom productivity and carbon fixation capacity.
[0041] Example 5 Iron-intercalated montmorillonite was applied to iron-deficient seawater through the following process: (1) Add 10g of iron-intercalated montmorillonite obtained in Example 1 to 1L of seawater to prepare an iron-intercalated montmorillonite concentrate with a concentration of 10g / L; (2) At every 0.2826m 2 Within the sea area, 1L of iron intercalation concentrate was evenly sprayed into iron-deficient seawater with an iron concentration of less than 0.3nM using a water spray gun, so that the iron intercalation montmorillonite concentration in the surface seawater reached 10mg / L.
[0042] Example 6 applies iron-intercalated montmorillonite to iron-deficient seawater through the following process: (1) Add 50g of iron-intercalated montmorillonite obtained in Example 1 to 1L of seawater to prepare an iron-intercalated montmorillonite concentrate with a concentration of 50g / L; (2) At every 0.2826m 2 In the sea area, 1L of iron intercalation concentrate was evenly sprayed into iron-deficient seawater with an iron concentration of less than 0.3nM using a water spray gun, so that the iron intercalation montmorillonite concentration in the surface seawater reached 50mg / L.
[0043] Tests showed that in Examples 5 and 6, the algal bloom reached its maximum scale on the 8th day, with a significant increase in the number of diatoms, a marked improvement in primary productivity, and a significant increase in carbon sequestration by diatoms in the experimental sea area.
[0044] It should be noted that the above descriptions are merely preferred embodiments of the present invention and should not limit the scope of protection of the technical solutions of the present invention. Any modifications made to the technical solutions described in the foregoing embodiments, or equivalent substitutions of technical features, by those skilled in the art within the spirit and principles of the present invention, should be included within the scope of protection of the present invention.
Claims
1. Methods for applying iron-intercalated montmorillonite to promote diatom blooms in iron-deficient seawater, including: Iron-intercalated montmorillonite was applied to iron-deficient seawater containing diatoms, wherein the iron-deficient seawater was seawater with an iron concentration of less than 0.3 nM, and the iron-intercalated montmorillonite was obtained through the following process: (1) Add sodium carbonate and / or hydrated sodium carbonate to an aqueous solution of iron salt, mix thoroughly to form a reddish-brown semi-transparent substance, and then age at room temperature to obtain an iron pillar solution; (2) Add montmorillonite to water and heat it to swell, thus obtaining a montmorillonite suspension; (3) The iron-supported liquid is slowly added dropwise to the montmorillonite suspension and heated and mixed. After the addition is completed, the mixture is continued for a certain period of time, and then aged at room temperature. After that, solid-liquid separation, solid drying and grinding are carried out in sequence to obtain the iron-intercalated montmorillonite.
2. The application method according to claim 1, characterized in that: in, The iron salt is selected from ferric nitrate and / or ferric chloride; and / or, the montmorillonite is selected from calcium-based montmorillonite and / or sodium-based montmorillonite.
3. The application method according to claim 1, characterized in that: The molar ratio of sodium carbonate and / or hydrated sodium carbonate to iron salt in the iron-supported solution is 0.5-2.5:1, and the pH of the iron-supported solution is <2.
4. The application method according to claim 1, characterized in that: in, The room temperature aging time is 20-24 h; and / or, the heating and swelling temperature is 50-70 °C; and / or, the heating and swelling time is 1.5-2.5 h; and / or, the heating and mixing temperature is 50-70 °C; and / or, the continued mixing time is 1.5-2.5 h; and / or, the solid drying temperature is 40-50 °C.
5. The application method according to claim 1, characterized in that: The solid-liquid ratio of the montmorillonite suspension is 1:45-55 g / mL.
6. The application method according to claim 1, characterized in that: The volume ratio of the iron-supported liquid to the montmorillonite suspension is 1-2:
1.
7. The application method according to claim 1, characterized in that: The diatoms are selected from one or more of the following: seaweed, chamomile, rhomboid algae, small ring algae, and boat-shaped algae.
8. The application method according to claim 1, characterized in that: The iron-intercalated montmorillonite was applied at a concentration of 10-50 mg / L in the iron-deficient seawater.
9. The application method according to claim 1, characterized in that: It includes: (1) Add the iron-intercalated montmorillonite to seawater to prepare an iron-intercalated montmorillonite concentrate with a concentration of 10-50 g / L; (2) The iron-intercalated montmorillonite concentrate is evenly sprayed onto the surface of the iron-deficient seawater using a spraying tool.
10. The application method according to claim 9, characterized in that: The spraying rate of the iron-intercalated montmorillonite concentrate was 0.2826 m³. 2 Spray 1L of water into the sea.