Method for improving carbon sequestration efficiency of diatom in water body and pH of water body

Abstract

The invention discloses a method for improving the carbon sequestration efficiency of diatom in a water body and the pH value of the water body, and relates to the technical field of carbon dioxide sequestration. The method comprises the following steps: adding a mixed mineral consisting of an aluminosilicate mineral and an iron magnesium silicate mineral into the diatom-containing water body, and culturing. The aluminosilicate mineral disclosed by the invention can be dissolved in a water body and release a Si nutrient element required by diatom growth, and meanwhile, the released Al element can enter diatom shells so as to inhibit dissolution of the diatom shells. The iron-magnesium silicate minerals can be dissolved in water and release nutrient elements such as Si, Mg and Fe, so that diatom breeding is promoted. Moreover, both the aluminosilicate minerals and the iron magnesium silicate minerals have certain surface adsorption specificity, so that the aluminosilicate minerals and the iron magnesium silicate minerals are flocculated with the diatom and the sedimentation of flocculates is accelerated, thereby increasing the amount of the flocculates deposited to the water bottom, improving the carbon sequestration efficiency and synchronously increasing the pH value of seawater. Therefore, acidification of water bodies such as seawater is inhibited while the carbon sequestration amount of the water bodies is increased.

Description

Technical Field

[0001] The invention relates to the technical field of carbon dioxide fixation, and in particular to a method for improving the carbon fixation efficiency of diatoms in water and the pH value of the water. Background Art

[0002] With the CO 2 The continuous increase of anthropogenic emissions has led to global warming, causing a series of negative environmental effects such as frequent extreme weather, rising sea levels, water hypoxia and acidification, threatening the sustainable development of human society. In the foreseeable future, fossil fuels will still be the main energy source of industrial society. Therefore, it is very important to develop carbon dioxide capture and storage technology. Large natural water bodies such as oceans and lakes are one of the most important active carbon reservoirs on the earth. They have played an important role in regulating climate change in the history of the earth and have huge carbon sink potential. Increasing carbon sinks in these natural water bodies through artificial measures can effectively achieve the regulation of the global carbon cycle and provide technical support for mitigating climate warming.

[0003] Diatoms are important microorganisms in the global water carbon cycle. They are found in large numbers in oceans, lakes and other water bodies and have high photosynthesis efficiency. For example, global marine diatoms contribute about 40% of the primary productivity of the ocean each year, fixing CO 2 The amount is up to 1×10 12 kg, is the atmospheric CO 2 In natural water bodies such as lakes and rivers, diatoms also play a key role, such as providing the basis of the food chain as primary producers, converting CO2 into 2 It is converted into particulate organic carbon for fixation, absorbs nutrients in the water (such as nitrogen and phosphorus), and increases the transparency of the water. In recent years, due to the impact of human activities, many water bodies have suffered from eutrophication, resulting in a decrease in the biomass of diatoms, which in turn affects the amount of carbon fixed by diatoms, causing serious impacts on the ecological functions of the water ecosystem such as the composition of the biological community and carbon fixation.

[0004] In order to deal with this problem, researchers have tried a variety of methods to increase the diatom biomass and carbon fixation efficiency of the water body, including adding soluble nutrients required by diatoms, changing the physical and chemical conditions of the water body, etc. For example, a certain amount of dissolved iron is added to the seawater through ocean iron fertilization (Li Hongliang et al., Comparison of field iron addition experiments between HNLC sea areas, Oceanographic Research, 2005) to promote the growth of phytoplankton such as diatoms. However, the results of the OIF experiment showed that although iron fertilization increased the outbreak of diatoms and other plankton, it did not significantly enhance the vertical carbon output to the deep sea. Most of the organic carbon carried by diatoms was lost during sedimentation due to diatom death, shell dissolution or organic matter decomposition (Joo-EunYoon et al., Reviews and syntheses: Ocean iron fertilization experiments-past, present, and future looking to a future Korean Iron Fertilization Experimentin the Southern Ocean (KIFES) project, Biogeosciences, 2018). Recent studies have found that (Zhou Linbin et al., Iron-Aluminum Hypothesis and Prospects of Marine Aluminum Fertilization and Sequestration Potential, Journal of Tropical Oceanography, 2023) adding dissolved aluminum to water bodies can enhance carbon fixation by upper ocean phytoplankton, reduce the decomposition rate of biogenic carbon, improve the efficiency of marine biological pumps, and increase carbon output and sequestration to the deep sea. However, dissolved aluminum has certain biological toxicity and is toxic to marine organisms (such as clogging the gills of fish and causing fish to die of hypoxia). Therefore, direct application of aluminum ions may produce ecological toxic effects. At present, the application of dissolved aluminum to water bodies is still in the research stage, and no specific technical methods for implementation have been proposed.

[0005] Yuan Peng et al. proposed that clay minerals (i.e., aluminosilicate minerals) can be added to water bodies to improve the sedimentation efficiency of microbial organic matter-mineral complexes and block the loss of particulate organic carbon, thereby improving the carbon fixation efficiency of the biological pump in water bodies and achieving CO2 reduction in water bodies. 2 Enhanced sink (Yuan Peng, Liu Dong, Mineral-enhanced biological pump: Aquatic CO2 based on mineral-microbe interaction 2Sedimentation strategy, Science Bulletin, 2022). The Chinese invention patent "A method for reducing the solubility of diatom shells and low-solubility diatoms and applications" (application number: 202211536954.5) uses organic silicon as a silicon source to form a diatom shell with a hydrophobic surface, reduce the solubility of the shell, and improve the carbon fixation efficiency of diatoms. The Chinese invention patent "A method for improving the carbon fixation efficiency of the Navicula biological pump" (application number: 202310555030.8) cultivates Navicula in a growth environment supplemented with sodium selenite. Under the stress of selenium, the siliceous skeleton of Navicula (i.e., the shell of Navicula) is enlarged, thereby increasing the silicon content, siliceous skeleton stability and sedimentation rate of a single diatom, thereby improving its biological pump carbon fixation efficiency.

[0006] However, the above-mentioned methods of adding aluminosilicate minerals or reducing the solubility of diatom shells based on regulating organic and inorganic nutrition lack clear data support for achieving a sustained increase in diatom biomass and improving the carbon fixation efficiency of particulate organic carbon.

[0007] In view of this, the present invention is proposed. Summary of the invention

[0008] The object of the present invention is to provide a method for improving the carbon fixation efficiency of diatoms in water and the pH value of water.

[0009] The present invention is achieved in that:

[0010] In a first aspect, the present invention provides a method for improving the carbon fixation efficiency and water pH of diatoms in water, which comprises applying a mixed mineral composed of aluminosilicate minerals and ferromagnesian silicate minerals to the water body containing diatoms for cultivation.

[0011] In an optional embodiment, the mass ratio of the aluminosilicate mineral to the ferromagnesian silicate mineral in the mixed mineral is 1 to 10:1.

[0012] In an optional embodiment, the amount of the mixed minerals added to the water body is 5-50 mg / L.

[0013] In an optional embodiment, the aluminosilicate mineral has a specific surface area of ​​50 m 2 / g of aluminosilicate minerals;

[0014] Preferably, the mass percentage of aluminum oxide in the aluminosilicate mineral is in the range of 10% to 50%, and the particle size is in the range of 0.1 to 38 μm;

[0015] Preferably, the aluminosilicate mineral includes at least one of montmorillonite, kaolinite and illite.

[0016] In an optional embodiment, the ferromagnesian silicate mineral has a weathering rate of 10 -9mol / m 2 / s or more ferromagnesian silicate minerals;

[0017] Preferably, the mass percentage of magnesium oxide in the ferromagnesian silicate mineral is in the range of 25% to 50%, the mass percentage of iron oxide is greater than 10%, and the particle size range is 0.1 to 38 μm;

[0018] Preferably, the ferromagnesian silicate minerals are olivine and pyroxene.

[0019] In an optional embodiment, the preparation method of the mixed mineral includes: first crushing the aluminosilicate mineral and the ferromagnesian silicate mineral to a particle size of 0.1 to 40 mm, then sieving out the 100-mesh undersize, using a disc vibrating mill at 600 to 800 rpm for 8 to 12 minutes, and then using a ball mill at 400 to 500 rpm for 10 to 20 minutes, passing through a 400-mesh sieve to obtain aluminosilicate mineral powder and ferromagnesian silicate mineral powder with a particle size of 0.1 to 38 μm; mixing the aluminosilicate mineral powder and the ferromagnesian silicate mineral powder at 100 to 150 rpm for 5 to 15 minutes.

[0020] In an optional embodiment, the method for preparing the diatom-containing water body comprises inoculating diatoms into the water body until the diatom content is 10,000 / L to 1,000,000 / L.

[0021] In an optional embodiment, the types of diatoms in the water body include seawater diatoms and freshwater diatoms;

[0022] Preferably, the diatom species is at least one of Thalassiosira and Chaetoceros.

[0023] In an optional embodiment, the water body is artificial seawater or natural seawater; a culture medium is added to the artificial seawater, and the components of the culture medium include: NaCl: 15-30 g / L, NaSO 4 : 3~5g / L, KCl: 0.3~1g / L, NaHCO 3 : 0.1~0.5g / L, KBr: 0.04~0.3g / L, H 3 BO 3 : 0.01~0.055g / L, NaF: 0.001~0.005g / L, MgCl 2 6H 2 O: 3-12 g / L, CaCl 2 ·2H 2 O: 2~5g / L, SrCl 2 6H 2 O: 0.01~0.8g / L, NaNO3 :0.65~0.9g / L、NaH 2 PO 4 ·H 2 O: 0.05~0.08g / L, Na 2 SiO 3 9H 2 O: 20~40mg / L.

[0024] In an optional embodiment, the culture conditions are a temperature of 10-30°C, a light intensity of 1000-10000 lux, a light-dark cycle of 12 hours of light and 12 hours of darkness, and continuous culture for 10-20 days.

[0025] The present invention has the following beneficial effects:

[0026] The method for improving the carbon fixation efficiency and water pH of diatoms in water provided by the present invention is to apply a mixture of aluminosilicate minerals and ferromagnesian silicate minerals to the water body, and utilize the different characteristics of aluminosilicate minerals and ferromagnesian silicate minerals. Aluminosilicate minerals contain Si and aluminum oxide, which can dissolve in the water body and release Si nutrients required for diatom growth. At the same time, the released Al element can enter the diatom shell to inhibit its dissolution. Ferromagnesian silicate minerals can dissolve in the water body and release nutrients such as Si, Mg, and Fe, thereby promoting the reproduction of diatoms. In addition, aluminosilicate minerals and ferromagnesian silicate minerals both have certain surface adsorption characteristics, so that they flocculate with diatoms and accelerate the sedimentation of floccules, thereby increasing the amount of them deposited to the bottom of the water and improving carbon fixation efficiency. At the same time, aluminosilicate minerals and ferromagnesian silicate minerals can also increase the silicon nutrition and bicarbonate of the water body, so that diatoms can continuously burst, and the pH of seawater can also be simultaneously increased. Therefore, the technical method proposed in the present invention achieves the goal of increasing the carbon fixation in diatom-containing water bodies such as seawater while simultaneously inhibiting the acidification of the water body, thus having dual ecological effects. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention will be described clearly and completely below. If the specific conditions are not specified in the embodiments, they are carried out according to conventional conditions or conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be purchased commercially.

[0028] The present invention has found that whether adding clay minerals or reducing the solubility of diatom shells by regulating organic and inorganic nutrition, the effect on the continuous increase of diatom biomass and the improvement of carbon fixation efficiency is not significant. This is mainly due to: 1. Since clay minerals are aluminosilicate minerals and lack the iron element necessary for diatoms, the addition of clay minerals cannot stimulate the diatoms to flourish and become the dominant population in the water body. 2. The diatom bloom cannot last. This is mainly because diatom photosynthesis consumes bicarbonate in the water body, which reduces the bicarbonate concentration in the water body, making it impossible to ensure the continuation of large-scale diatom blooms, and it is difficult to achieve the purpose of increasing diatom biomass and carbon fixation.

[0029] To this end, the present invention proposes a method for improving the carbon fixation efficiency of diatoms in water and the pH of the water body, which includes applying a mixed mineral composed of aluminosilicate minerals and ferromagnesian silicate minerals to the water body containing diatoms, cultivating them, promoting the growth and organic carbon synthesis of diatoms, and improving the pH of the water body.

[0030] The present invention applies a mixture of aluminum silicate minerals and ferromagnesian silicate minerals to the water body, utilizes the different characteristics of aluminum silicate minerals and ferromagnesian silicate minerals, promotes the growth of diatoms in the water body, increases their biomass, and increases the carbon fixation of the diatom biological pump by reducing the decomposition of diatom shells. At the same time, the silicon nutrition and bicarbonate of the water body are increased, so that the diatoms can continuously burst, and the pH of seawater can be increased simultaneously. Therefore, while increasing the carbon fixation of the water body, the acidification of water bodies such as seawater is suppressed.

[0031] Specifically, the present invention provides a method for improving the carbon fixation efficiency of diatoms in water and the pH of the water, comprising the following steps:

[0032] (1) Preparation of mixed minerals.

[0033] First, aluminosilicate minerals and ferromagnesian silicate minerals were screened, among which aluminosilicate minerals had a specific surface area of ​​50m 2 / g of aluminosilicate minerals; the mass percentage of aluminum oxide in the aluminosilicate minerals ranges from 10% to 50%, and the particle size ranges from 0.1 to 38 μm. Preferably, the aluminosilicate minerals include at least one of montmorillonite, kaolinite and illite.

[0034] Among them, the aluminum oxide content in montmorillonite reaches 10-25%, the aluminum oxide content in kaolin reaches 30-45%, and the aluminum oxide content in illite reaches 30-50%.

[0035] In the present invention, the aluminosilicate mineral is limited to have a high specific surface area, which has good surface adsorption characteristics, so that it flocculates with diatoms and accelerates the sedimentation of the floccules, thereby increasing the amount of its deposition to the bottom of the water and improving the carbon fixation efficiency. Furthermore, the aluminosilicate mineral contains Si and aluminum oxide, which can dissolve in the water and release the Si nutrient element required for the growth of diatoms. At the same time, the released Al element can enter the diatom shell to inhibit its dissolution.

[0036] Magnesian silicate minerals have a weathering rate of 10 -9 mol / m 2 / s or more ferromagnesian silicate minerals; the mass percentage of magnesium oxide in the ferromagnesian silicate minerals ranges from 25% to 50%, the mass percentage of iron oxide ranges from more than 10%, and the particle size ranges from 0.1 to 38 μm. Preferably, the ferromagnesian silicate minerals are olivine and pyroxene. Among them, the content of magnesium oxide in olivine is 43%-50%, and the content of iron oxide is 14-15%.

[0037] In the present invention, by selecting the weathering rate between 10 -9 mol / m 2 / s or more as the ferromagnesian silicate mineral of the present invention, the greater the weathering rate, the faster it dissolves in the water and releases nutrients such as Si, Mg, and Fe, thereby promoting the reproduction of diatoms. In addition, the ferromagnesian silicate mineral also has certain surface adsorption characteristics, which makes it flocculate with diatoms and accelerates the sedimentation of flocs, thereby increasing the amount of flocculation to the bottom of the water and improving the carbon fixation efficiency.

[0038] In addition, since the water contains diatoms, diatoms can have a certain dissolution effect on minerals, further accelerating the weathering of ferromagnesian silicate minerals such as olivine, which have high chemical weathering rates, thereby increasing the bicarbonate concentration in the water and raising the pH of the water, thereby improving the carbon fixation efficiency of the water.

[0039] The screened aluminosilicate minerals and ferromagnesian silicate minerals are first crushed to a particle size of 0.1-40 mm, then the 100-mesh undersize is screened out, a disc vibrating mill is used to grind for 8-12 min at 600-800 rpm, and then a ball mill is used to grind for 10-20 min at 400-500 rpm, and a 400-mesh sieve is passed to obtain aluminosilicate mineral powder and ferromagnesian silicate mineral powder with a particle size of 0.1-38 μm; the aluminosilicate mineral powder and ferromagnesian silicate mineral powder are mixed at 100-150 rpm for 5-15 min to obtain. In the present invention, by gradually crushing and grinding, the particle size of the aluminosilicate mineral and the ferromagnesian silicate mineral can reach the micron level, which is easier to disperse and dissolve in water.

[0040] The mass ratio of the aluminum silicate mineral to the ferromagnesian silicate mineral in the mixed mineral is 1 to 10: 1. A better effect can be achieved by controlling the mass ratio of the aluminum silicate mineral to the ferromagnesian silicate mineral.

[0041] (2) Preparing a water body containing diatoms.

[0042] The method for preparing a water body containing diatoms comprises inoculating diatoms into a water body (artificial seawater or natural seawater) until the content of diatoms is 10,000 / L to 1,000,000 / L. The types of diatoms in the water body include seawater diatoms and freshwater diatoms; preferably, the type of diatoms is at least one of Thalassiosira and Chaetoceros.

[0043] The nitrogen, phosphorus and silicon contents in natural seawater range from 0.5 mg per liter to 340 mg per liter of nitrogen, 0.1 mg per liter to 15 mg per liter of phosphorus, and 0.3 mg per liter to 30 mg per liter of silicon.

[0044] Artificial seawater is simulated according to the composition of natural seawater. In the present invention, artificial seawater is simulated by adding culture medium to artificial seawater. The amount of the reagents used in the culture medium needs to be within the range of natural seawater after conversion into nitrogen and phosphorus content. Specifically, the components of the culture medium include: NaCl: 15-30g / L, NaSO 4 : 3~5g / L, KCl: 0.3~1g / L, NaHCO 3 : 0.1~0.5g / L, KBr: 0.04~0.3g / L, H 3 BO 3 : 0.01~0.055g / L, NaF: 0.001~0.005g / L, MgCl 2 6H 2 O: 3-12 g / L, CaCl 2 ·2H 2 O: 2~5g / L, SrCl 2 6H 2 O: 0.01~0.8g / L, NaNO 3 :0.65~0.9g / L、NaH 2 PO 4 ·H 2 O: 0.05~0.08g / L, Na 2 SiO 3 9H 2 O: 20~40mg / L.

[0045] (3) Adding a mixed mineral composed of aluminum silicate minerals and ferromagnesian silicate minerals to the water body containing diatoms for cultivation. The experimental device is a laboratory light incubator equipped with an indoor light source and a temperature control system.

[0046] The prepared artificial seawater diatom water was transferred into a 5L high-transmittance conical flask; after 3 hours of adaptation, mixed natural silicate minerals were added and placed in a light incubator; the culture temperature was set to 10-30°C, the light intensity was 1000-10000 lux, and the light-dark cycle was 12 hours of light and 12 hours of darkness. The amount of mixed minerals added to the water body was 5-50 mg / L. The experiment lasted for 10-20 days, and the conical flask was shaken three times a day to measure the pH value and chlorophyll a concentration on the tenth day. Solid samples were collected on the 10th day of the experiment to determine the content and sedimentation rate of particulate organic carbon (POC). Among them, chlorophyll a is an important pigment contained in the various photosynthetic pigments of Thalassium marinum, which plays a role in absorbing and transmitting light energy in photosynthesis. Thalassium marinum grows by photosynthesis, and its content can reflect the growth status of Thalassium marinum in the water body. In addition, in Thalassiosira, chlorophyll a accounts for 1% to 2% of the dry weight of organic matter, so it is also an important indicator for estimating primary productivity and biomass. Therefore, by measuring the chlorophyll a content in water bodies, we can understand the biomass of Thalassiosira and effectively grasp the growth of algae.

[0047] The features and performance of the present invention are further described in detail below in conjunction with the embodiments.

[0048] Example 1

[0049] The culture device used in this example is a 5L high-transmittance conical flask. The experimental water body is artificial seawater prepared in the laboratory. The culture medium is added to the artificial seawater. The components of the culture medium include: NaCl: 20.76g / L, NaSO 4 :3.48g / L, KCl: 0.59g / L, NaHCO 3 :0.17g / L, KBr: 0.08g / L, H 3 BO 3 :0.02g / L, NaF: 0.003g / L, MgCl 2 6H 2 O: 9.39 g / L, CaCl 2 ·2H 2 O: 1.32 g / L, SrCl 2 6H 2 O: 0.2g / L, NaNO 3 :0.75g / L、NaH 2 PO 4 ·H 2 O: 0.05g / L, Na 2 SiO 3 9H 2 O: 30mg / L.

[0050] Chaetoceros and Thalassiosira were inoculated into two portions of artificial seawater, respectively, until the initial density of Chaetoceros and Thalassiosira was 10,000 cells / L, respectively. 5 L of artificial seawater inoculated with Chaetoceros and 5 L of artificial seawater inoculated with Thalassiosira were added into conical flasks, respectively, and placed in a light incubator. The light intensity was set to 2000 lux, the temperature was controlled at 20-25°C, and the light-dark cycle was 12 hours of light / 12 hours of darkness.

[0051] At the beginning of the experiment, a mineral combination of montmorillonite and olivine (mass ratio of 1:1) was added, and the mixed mineral addition amount was 50 mg / L. The experiment lasted for 10 days, during which the conical flask was shaken to ensure uniform distribution of the minerals.

[0052] After the cultivation, particulate organic carbon (POC) was collected and its content, sedimentation rate and water pH were determined.

[0053] Embodiment 2-4

[0054] This embodiment is basically the same as embodiment 1, except that the mixed minerals added in this embodiment are different from those in embodiment 1:

[0055] In Example 2, the mixed mineral is a mineral combination of montmorillonite and pyroxene (mass ratio is 1:1);

[0056] In Example 3, the mixed mineral is a mineral combination of kaolinite and olivine (mass ratio is 1:1);

[0057] The mixed mineral in Example 4 is a mineral combination of illite and olivine (mass ratio is 1:1).

[0058] Embodiment 5-7

[0059] This embodiment is basically the same as Embodiment 1, except that the mass ratio of montmorillonite to olivine in the mixed minerals added in this embodiment is different from that in Embodiment 1:

[0060] In Example 5, the mass ratio of montmorillonite to olivine is 2:1;

[0061] In Example 6, the mass ratio of montmorillonite to olivine is 5:1;

[0062] In Example 7, the mass ratio of montmorillonite to olivine is 10:1.

[0063] Embodiment 8-9

[0064] This embodiment is basically the same as embodiment 1, except that the amount of mixed minerals added is different:

[0065] In Example 8, the amount of mixed mineral added was 20 mg / L;

[0066] In Example 9, the amount of mixed mineral added is 30 mg / L.

[0067] Example 10

[0068] On the basis of Example 1, this example further conducted a large volume water column experiment to verify the carbon fixation efficiency and pH adjustment effect of the mineral combination of montmorillonite and olivine on a mixed system of various diatoms (Chaetoceros and Thalassiosira).

[0069] The experiment used an indoor water column device with a diameter of 1.7 meters and a height of 3 meters. The water body was 5 tons of filtered natural seawater, inoculated with a mixed algae liquid of Chaetoceros and Thalassiosira, and the diatom density was 10,000 per liter.

[0070] At the beginning of the experiment, the minerals were added in a ratio of montmorillonite to olivine (1:1) at a dosage of 50 mg / L. The experiment lasted for 10 days, and particulate organic carbon (POC) was collected to determine its content, sedimentation rate, and water pH.

[0071] Comparative Example 1

[0072] This comparative example is substantially the same as Example 1, except that the step of adding the mixed minerals is omitted in this comparative example.

[0073] Comparative Example 2

[0074] This comparative example is basically the same as Example 1, except that the mass ratio of montmorillonite to olivine in this comparative example is 1:2;

[0075] Comparative Example 3

[0076] This comparative example is substantially the same as Example 1, except that only 50 mg / L of montmorillonite is added in this comparative example.

[0077] Comparative Example 4

[0078] This comparative example is substantially the same as Example 1, except that only 50 mg / L of olivine is added in this comparative example.

[0079] Comparative Example 5

[0080] This comparative example is basically the same as Example 1, except that the aluminosilicate mineral selected in this comparative example is montmorillonite, which has a specific surface area of ​​14.12% and an alumina content of 56.2 m 2 / g; the ferromagnesian silicate mineral is olivine, with a magnesium oxide content of 42% and an iron oxide content of 14%.

[0081] Experimental example

[0082] After the cultivation of the above-mentioned Examples 1-10 and Comparative Examples 1-5 was completed, the particulate organic carbon was collected, and the organic carbon content, sedimentation rate and water pH were measured. The test method includes:

[0083] (1) Organic carbon content: Take 50 mL of algae liquid, centrifuge and discard the supernatant, then wash with deionized water three times, freeze-dry the sample and weigh it. Take about 2.00 mg of the mixed sample and put it into a 6×12 mm tin boat. Use Vario ELⅢ elemental analyzer to analyze the carbon element of the sample. Each sample is tested three times in parallel, and the average value is used for analysis and comparative study to calculate the carbon content of diatoms.

[0084] (2) Sedimentation rate: After the co-culture system is fully stirred, it is transferred to a transparent sedimentation column for uniform distribution. Next, the sample is placed in a sedimentation container and the starting height is recorded. The timing is then started. The sedimentation height and time are recorded at certain time intervals. Finally, the rate is calculated using a formula and a curve is drawn to analyze the sedimentation characteristics.

[0085] (3) Water pH: Take 20 ml of sample solution and filter it, then measure the pH of the filtrate using a pH meter.

[0086] Please refer to Table 1 for the test results:

[0087] Table 1. Test results statistics for different examples

[0088]

[0089]

[0090] As can be seen from the above table, from the data of Example 1 and Comparative Example 1, it can be seen that after adding the combination of montmorillonite and olivine, the particulate organic carbon content of Chaetoceros and Thalassiosira increased by 22.2% and 27.2%, respectively, the sedimentation rate increased by 10.97 and 19.77 times, and the pH value of the water body increased by 0.24 and 0.26. From the data of Example 2 and Comparative Example 1, it can be seen that the combination of montmorillonite and pyroxene increases the particulate organic carbon content of Chaetoceros and Thalassiosira by 21.3% and 24.1%, respectively, the sedimentation rate increased by 17.51 ​​and 17.99 times, and the pH value of the water body increased by 0.22 and 0.23. From the data of Example 3 and Comparative Example 1, it can be seen that after adding the combination of olivine and kaolinite, the particulate organic carbon content of Chaetoceros and Thalassiosira increased by 17.5% and 16.4%, respectively, the sedimentation rate increased by 14.14 and 23.09 times, and the pH value of the water body increased by 0.13 and 0.10. From the data of Example 4 and Comparative Example 1, it can be seen that after adding illite and olivine in combination, the particulate organic carbon content of Chaetoceros and Thalassiosira increased by 10% and 10.3%, respectively, the sedimentation rate increased by 12.8 and 22.26 times, and the pH value of the water body increased by 0.04 and 0.02. From the data of Examples 5-7, it can be seen that with the increase in the content of montmorillonite, the particulate organic carbon content of Chaetoceros and Thalassiosira gradually increased, and the sedimentation rate and the pH value of the water body were further improved. From the data of Examples 8-9, it can be seen that the change in the addition amount of the mixed mineral will cause a certain change in the particulate organic carbon content, sedimentation rate and pH value of the water body of Chaetoceros and Thalassiosira, but the addition amount within the scope of the present invention has a good effect. It can be seen from the data of Example 10 and Comparative Example 1 that in a large-scale system, the 1:1 combination of olivine and montmorillonite still significantly improves the carbon fixation efficiency of diatoms. Compared with the mixed algae without added mineral treatment (the average of Chaetoceros and Thalassiosira in Comparative Example 1 is used as the data of the mixed algae), the particulate organic carbon content of the diatoms with added mixed minerals increased by 165.7%, the sedimentation rate of the particulate organic carbon increased by 15.8 times, and the pH value of the water body increased by 0.28.

[0091] It can be seen from the data of Example 1 and Comparative Examples 2-5 that when the mass ratio of montmorillonite to olivine is not within the scope of the present application, at this time, the excessive amount of olivine will result in the mixture having no significant improvement in the organic carbon content of Chaetoceros and Thalassiosira, and even the organic carbon content of Chaetoceros is slightly reduced. In addition, the sedimentation rate and pH improvement effects are also significantly worse than those of Example 1, and are not much different from the comparative example. When only montmorillonite or only olivine is added, the organic carbon content of Chaetoceros and Thalassiosira is not only not improved, but also reduced, and the sedimentation rate and pH improvement effects are also significantly worse than those of Example 1, and are not much different from the comparative example. When the performance indicators of montmorillonite and olivine are not within the scope of the present application, their effects are also significantly worse than those of Example 1.

[0092] In summary, the method for improving the carbon fixation efficiency and water pH of diatoms in water provided by the present invention is to apply a mixture of aluminosilicate minerals and ferromagnesian silicate minerals to the water body, and utilize the different characteristics of aluminosilicate minerals and ferromagnesian silicate minerals. Aluminosilicate minerals contain Si and aluminum oxide, which can dissolve in the water body and release Si nutrients required for diatom growth. At the same time, the released Al element can enter the diatom shell to inhibit its dissolution. Ferromagnesian silicate minerals can dissolve in the water body and release nutrients such as Si, Mg, and Fe, thereby promoting the reproduction of diatoms. In addition, aluminosilicate minerals and ferromagnesian silicate minerals both have certain surface adsorption characteristics, so that they flocculate with diatoms and accelerate the sedimentation of floccules, thereby increasing the amount of them deposited to the bottom of the water and improving carbon fixation efficiency. At the same time, aluminosilicate minerals and ferromagnesian silicate minerals can also increase the silicon nutrition and bicarbonate of the water body, so that diatoms can continuously burst, and can also simultaneously increase the pH of seawater. Thus, while increasing the amount of carbon fixation in the water body, the acidification of water bodies such as seawater is suppressed.

[0093] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for improving the carbon fixation efficiency of diatoms in water and the pH of water, characterized in that: The method comprises adding a mixed mineral composed of an aluminosilicate mineral and a ferromagnesian silicate mineral to a water body containing diatoms for cultivation.

2. The method for improving the carbon fixation efficiency of diatoms in water and the pH of water according to claim 1, characterized in that: The mass ratio of the aluminosilicate mineral to the ferromagnesian silicate mineral in the mixed mineral is 1 to 10:

1.

3. The method for improving the carbon fixation efficiency of diatoms in water and the pH of water according to claim 1, characterized in that: The amount of the mixed mineral added to the water body is 5-50 mg / L.

4. The method for improving the carbon fixation efficiency of diatoms in water and the pH of water according to claim 1, characterized in that: The aluminosilicate mineral has a specific surface area of ​​50 m 2 / g of aluminosilicate minerals; Preferably, the mass percentage of aluminum oxide in the aluminosilicate mineral is in the range of 10% to 50%, and the particle size is in the range of 0.1 to 38 μm; Preferably, the aluminosilicate mineral includes at least one of montmorillonite, kaolinite and illite.

5. The method for improving the carbon fixation efficiency of diatoms in water and the pH of water according to claim 1, characterized in that: The ferromagnesian silicate mineral has a weathering rate of 10 -7 mol / m 2 / s or more ferromagnesian silicate minerals; Preferably, the mass percentage of magnesium oxide in the ferromagnesian silicate mineral is in the range of 25% to 50%, the mass percentage of iron oxide is greater than 10%, and the particle size range is 0.1 to 38 μm; Preferably, the ferromagnesian silicate minerals are olivine and pyroxene.

6. The method for improving the carbon fixation efficiency of diatoms in water and the pH of water according to claim 1, characterized in that: The preparation method of the mixed mineral comprises: first crushing the aluminosilicate mineral and the ferromagnesian silicate mineral to a particle size of 0.1 to 40 mm, then sieving out the 100-mesh undersize, grinding them at 600 to 800 rpm for 8 to 12 minutes using a disc vibrating mill, then grinding them at 400 to 500 rpm for 10 to 20 minutes using a ball mill, and passing through a 400-mesh sieve to obtain aluminosilicate mineral powder and ferromagnesian silicate mineral powder with a particle size of 0.1 to 38 μm; and mixing the aluminosilicate mineral powder and the ferromagnesian silicate mineral powder at 100 to 150 rpm for 5 to 15 minutes.

7. The method for improving the carbon fixation efficiency of diatoms in water and the pH of water according to claim 1, characterized in that: The method for preparing the diatom-containing water body comprises inoculating diatoms into the water body until the content of diatoms is 10,000 / L to 1,000,000 / L.

8. The method for improving the carbon fixation efficiency of diatoms in water and the pH of water according to claim 7, characterized in that: The types of diatoms in the water body include seawater diatoms and freshwater diatoms; Preferably, the diatom species is at least one of Thalassiosira and Chaetoceros.

9. The method for improving the carbon fixation efficiency of diatoms in water and the pH of water according to claim 7, characterized in that: The water body is artificial seawater or natural seawater; a culture medium is added to the artificial seawater, and the components of the culture medium include: NaCl: 15-30 g / L, NaSO4: 3-5 g / L, KCl: 0.3-1 g / L, NaHCO3: 0.1-0.5 g / L, KBr: 0.04-0.3 g / L, H3BO3: 0.01-0.055 g / L, NaF: 0.001-0.005 g / L, MgCl2·6H2O: 3-12 g / L, CaCl2·2H2O: 2-5 g / L, SrCl2·6H2O: 0.01-0.8 g / L, NaNO3: 0.65-0.9 g / L, NaH2PO4·H2O: 0.05-0.08 g / L, and Na2SiO3·9H2O: 20-40 mg / L.

10. The method for improving the carbon fixation efficiency of diatoms in water and the pH of water according to claim 1, characterized in that: The culture conditions are as follows: a temperature of 10 to 30° C., a light intensity of 1000 to 10000 lux, a light-dark cycle of 12 hours of light and 12 hours of darkness, and continuous culture for 10 to 20 days.

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