A method for increasing the water body carbon sink and alleviating eutrophication by using industrial waste gas CO2

Abstract

The present invention discloses a method for increasing the carbon sink of water bodies and alleviating eutrophication by using industrial waste gas CO₂, which includes the following steps: cultivating an aquatic ecosystem with symbiotic planktonic and submerged plants; the aquatic ecosystem refers to an ecosystem composed of an aquatic biological community and a water environment; injecting industrial waste gas CO₂ into the water body of the aquatic ecosystem to make the partial pressure of CO₂ in the water body of the aquatic ecosystem reach at least 570 ppm; according to the content and ratio of nitrogen and phosphorus in the water body of the aquatic ecosystem in the first step, adjusting the injection amount of CO₂ and the content and ratio of nitrogen and phosphorus in the water body of the aquatic ecosystem to make the molar ratio of CO₂ to NO₃⁻ greater than 50 and the molar ratio of CO₂ to PO₄³⁻ greater than 3000; adjusting the community structure of planktonic or submerged plants, which solves the problems of high cost, slow effect, difficult promotion and insignificant effect in the existing general technologies, thereby achieving the improvement of the carbon sink amount of water bodies and the alleviation of water body eutrophication.

Description

Technical Field

[0001] The present invention relates to the technical fields of water body carbon sink amount and water body eutrophication, and particularly relates to a method for increasing the water body carbon sink and alleviating eutrophication by using industrial waste gas CO2. Background Art

[0002] The CO2 emissions caused by fossil fuel combustion have disrupted the relatively balanced carbon source-sink process in nature. To address climate change, on the one hand, the impact of CO2 on the climate can be reduced through energy conservation and emission reduction, and on the other hand, the so-called Carbon Capture and Storage (CCS) technology can be used to increase the carbon capture and storage capacity, so as to achieve the goal of controlling global warming. In addition to artificial CCS technology, some physical, chemical, and biological processes in nature, such as rock weathering and biological photosynthesis, can also achieve the capture and storage of atmospheric CO2, which can be called natural process CCS. In recent years, water body carbon sequestration and enhancement technologies have received extensive attention. The main idea is to develop corresponding technical methods based on mechanisms such as biological pumps, microbial carbon pumps, and carbonate pumps or their combinations. For example, based on the principle of biological pumps, geoengineering technologies such as Ocean Iron Fertilization have been developed to increase the ocean carbon sink. It has been found that the photosynthesis of aquatic photosynthetic organisms is significantly limited by carbon, especially in karst and eutrophic water bodies with high pH. High CO2 concentration can stimulate aquatic photosynthetic carbon fixation and increase the water body carbon sink amount. In addition, the water body environment with high CO2 concentration is conducive to the growth of green algae-diatoms and submerged plants, and can alleviate the occurrence of cyanobacteria-type eutrophication to a certain extent.

[0003] At present, most general technologies mainly consider the stimulating effects of factors such as light intensity, temperature, and nutrients on aquatic photosynthesis. The common problems of these invention technologies are that light and temperature are often not the main limiting factors for photosynthesis, and the promotion of photosynthesis is small. Moreover, they often act together with other factors, such as nutrient elements, resulting in a low input-output ratio and making it impossible to be widely promoted on a large scale; excessive nutrients will cause water body eutrophication and pose a threat to water quality safety.

[0004] A few invention technologies that consider the stimulating effect of carbon on photosynthesis mainly consider the influence of dissolved inorganic carbon (DIC) in the water body. The carbon sequestration process involves rock weathering, water cycle, and aquatic carbon fixation, etc. Its carbon sequestration efficiency is jointly regulated by multiple factors, with many influencing factors for carbon sequestration efficiency and limited application scenarios. And such methods often involve changes in land use types, and the impacts on aspects such as economy, agriculture, and environment need to be considered comprehensively, resulting in problems such as high cost, slow effect, difficult promotion, and insignificant effect of carbon sequestration and enhancement technologies. Summary of the Invention

[0005] Based on this, a method for increasing the water body carbon sink and alleviating eutrophication by using industrial waste gas CO2 is proposed, which solves the problems of high cost, slow effect, difficult promotion and insignificant effect in the existing carbon sequestration and sink-increasing technologies, so as to increase the water body carbon sink amount and alleviate water body eutrophication.

[0006] The technical solution of the present invention is as follows:

[0007] A method for increasing the water body carbon sink and alleviating eutrophication by using industrial waste gas CO2, comprising the following steps:

[0008] Step 1: Cultivate an aquatic ecosystem with symbiotic planktonic and submerged plants;

[0009] The aquatic ecosystem refers to an ecosystem composed of an aquatic biological community and a water environment;

[0010] Step 2: Inject industrial waste gas CO2 into the water body of the aquatic ecosystem in Step 1, so that the CO2 partial pressure in the water body of the aquatic ecosystem reaches at least 570 ppm;

[0011] Step 3: According to the content and ratio of nitrogen and phosphorus in the water body of the aquatic ecosystem in Step 1, adjust the injection amount of CO2 in Step 2 and the content and ratio of nitrogen and phosphorus in the water body of the aquatic ecosystem, so that the molar ratio of CO2 to NO3 - is greater than 50, and the molar ratio of CO2 to PO4 3- is greater than 3000;

[0012] Step 4: While performing Step 3, adjust the structure of the planktonic or submerged plant community.

[0013] The principle of the above solution:

[0014] The present invention makes full use of the relatively low-cost industrial waste gas CO2, introduces CO2 into the aquatic ecosystem, increases the CO2 concentration in the water body. On the one hand, it plays a CO2 fertilization effect, stimulates the water body productivity, and increases the carbon sink amount of aquatic photosynthesis, which has important carbon sink significance and provides an economic and feasible sink-increasing path for effectively coping with climate change. On the other hand, the formed water body environment with high CO2 concentration, high C or N, and C or P is beneficial to the growth of submerged plants, delays the process of water body eutrophication, not only improves the water quality conditions but also forms an aquatic ecosystem with landscape value. The water body CO2 can not only promote the photosynthesis of aquatic photosynthetic organisms, increase the water body carbon sink amount, but also adjust the proportion of water body nutrient elements, and then regulate the structure of the planktonic or submerged plant community, so that the water body is mainly composed of submerged plants and planktonic plants, and the planktonic plants are mainly composed of green algae and diatoms.

[0015] Preferably, in the present invention, step one includes selecting submerged plant species, controlling the planting density range of submerged plants, and controlling the biomass of phytoplankton; the selection of submerged plant species is to select submerged plants that can repair eutrophication and utilize HCO3 in the water body - , and submerged plants that can utilize CO2; the planting density range of submerged plants is controlled to be 200 - 500 plants / m 3 ; the biomass of phytoplankton is controlled to be below 10 μg / L.

[0016] Preferably, in the present invention, for step two, it is necessary to set the injection points of CO2 at different depths, positions, and flow rates according to the coverage area, water depth, and flow rate of the water body; it is also necessary to adjust the daily injection time of CO2 according to the daily meteorological conditions such as air temperature, rainfall, radiation intensity, and wind speed, as well as the seasonal changes.

[0017] The beneficial effects of the present invention are:

[0018] 1. It is beneficial to alleviate the development of the eutrophication process, achieve the goal of synchronously achieving carbon sequestration increase and eutrophication mitigation, alleviate eutrophication, reduce the carbon sequestration cost by increasing carbon sequestration, improve the water quality condition, achieve the synchronous achievement of carbon sequestration increase and eutrophication mitigation, and greatly improve the water body carbon sequestration efficiency by using industrial - emitted CO2, solving the problems in general technologies such as high cost, slow effect, difficult promotion, and insignificant effect of carbon sequestration and enhancement technologies, thereby achieving an increase in the water body carbon sequestration amount and alleviating water body eutrophication.

[0019] 2. It is beneficial to ensure a considerable number of primary producers in the water body and achieve the full utilization of CO2.

[0020] 3. Ensure that there is sufficient CO2 in the water body to meet the carbon demand for photosynthesis, stimulate photosynthesis, and increase the aquatic carbon sequestration amount. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is a schematic flow chart of a method for increasing water body carbon sequestration and alleviating eutrophication by using industrial waste gas CO2 described in an embodiment of the present invention;

[0022] Figure 2 is a schematic diagram showing the relationship between the planting density and biomass of Ceratophyllum demersum described in an embodiment of the present invention;

[0023] Figure 3 is a schematic diagram showing the relationship between the planting density and biomass of Myriophyllum spicatum described in an embodiment of the present invention;

[0024] Figure 4 is a schematic diagram showing the relationship between the planting density and biomass of Elodea nuttallii described in an embodiment of the present invention;

[0025] Figure 5It is a schematic diagram of the relationship between the biomass of submerged plants and the biomass of phytoplankton in the embodiments of the present invention;

[0026] Figure 6 It is a schematic diagram of the relationship between DIC (dissolved inorganic carbon) and the amount of organic carbon sink in the embodiments of the present invention;

[0027] Figure 7 It is a schematic diagram of the relationship between the partial pressure of CO2 and chlorophyll in the embodiments of the present invention;

[0028] Figure 8 It is a schematic diagram of the relationship between the molar ratio of CO2 and NO3 - and cyanobacteria or diatoms + green algae in the embodiments of the present invention;

[0029] Figure 9 It is a schematic diagram of the relationship between the molar ratio of CO2 and PO4 3 - and cyanobacteria or diatoms + green algae in the embodiments of the present invention;

[0030] Figure 10 It is a schematic diagram of the relationship between the molar ratio of CO2 and NO3 - and submerged plants in the embodiments of the present invention;

[0031] Figure 11 It is a schematic diagram of the relationship between the molar ratio of CO2 and PO4 3 - and submerged plants in the embodiments of the present invention; Detailed implementation manners

[0032] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0033] Embodiment:

[0034] A method for increasing the carbon sink in water bodies and alleviating eutrophication by using industrial waste gas CO2 includes the following steps:

[0035] Step 1: Cultivate an aquatic ecosystem with symbiotic planktonic and submerged plants;

[0036] The aquatic ecosystem refers to an ecosystem composed of an aquatic biological community and a water environment;

[0037] Step 2: Inject industrial waste gas CO2 into the water body of the aquatic ecosystem in Step 1 so that the partial pressure of CO2 in the water body of the aquatic ecosystem reaches at least 570 ppm;

[0038] Step 3: According to the content and ratio of nitrogen and phosphorus in the water body of the aquatic ecosystem in Step 1, adjust the injection amount of CO2 in Step 2 and the content and ratio of nitrogen and phosphorus in the water body of the aquatic ecosystem so that the molar ratio of CO2 and NO3 - is greater than 50, and the molar ratio of CO2 and PO43- The molar ratio is greater than 3000;

[0039] Step 4: While performing Step 3, adjust the structure of the floating or submerged plant community.

[0040] The present invention makes full use of the relatively low-cost industrial waste gas CO2, introduces CO2 into the aquatic ecosystem, increases the CO2 concentration in the water body. On the one hand, it plays a CO2 fertilization effect, stimulates the water body productivity, increases the carbon sink amount of aquatic photosynthesis, has important carbon sink significance, and provides an economic and feasible carbon sink enhancement path for effectively coping with climate change. On the other hand, the formed water body environment with high CO2 concentration, high C or N, and C or P is beneficial to the growth of submerged plants, delays the process of water body eutrophication, not only improves the water quality conditions but also forms an aquatic ecosystem with landscape value. The water body CO2 can not only promote the photosynthesis of aquatic photosynthetic organisms, increase the water body carbon sink amount, but also regulate the proportion of water body nutrient elements, and then regulate the structure of the floating or submerged plant community, so that the water body is mainly composed of submerged plants and phytoplankton, and the phytoplankton is mainly composed of green algae and diatoms, which is beneficial to alleviating the development of the eutrophication process, achieving the goal of synchronously achieving carbon sink enhancement and eutrophication alleviation, alleviating eutrophication, reducing the carbon sink cost by increasing the carbon sink, and improving the water quality condition, achieving the synchronous achievement of carbon sink enhancement and eutrophication alleviation, greatly improving the water body carbon sequestration and enhancement efficiency by using industrial emissions of CO2, solving the problems of high cost, slow effect, difficult promotion and insignificant effect existing in general technologies in carbon sequestration and enhancement technology, so as to increase the water body carbon sink amount and alleviate the water body eutrophication.

[0041] As a further preference of the present invention, Step 1 includes selecting the types of submerged plants, controlling the planting density range of submerged plants, and controlling the biomass of phytoplankton; the selection of the types of submerged plants is to select submerged plants that can repair eutrophication, can utilize HCO3 in the water body - , and can utilize CO2; the planting density range of the submerged plants is controlled to be 200 - 500 plants / m 3 ; the biomass of the phytoplankton is controlled to be below 10 μg / L, which is beneficial to ensuring a considerable number of primary producers in the water body and realizing the full utilization of CO2.

[0042] As a further preference of the present invention, in Step 2, it is necessary to set the CO2 injection points with different depths, positions, and flow rates according to the coverage area, water depth, and flow rate of the water body; it is also necessary to adjust the daily CO2 injection time according to the daily meteorological conditions such as air temperature, rainfall, radiation intensity, and wind speed and the seasonal change situation, which is beneficial to ensuring that there is sufficient CO2 in the water body to meet the carbon demand for photosynthesis, stimulating photosynthesis, and increasing the aquatic carbon sink amount.

[0043] In the present invention, it is necessary to cultivate an aquatic ecosystem in which floating and submerged plants coexist. This step includes the types of submerged plants, controlling the planting density range of submerged plants, and controlling the biomass of phytoplankton.

[0044] Types of submerged plants: Select typical submerged plants for the restoration of eutrophic water bodies, and at the same time, it is necessary to meet the submerged plants that can utilize HCO3 in the water body - and can also utilize CO2 to better achieve the carbon sink enhancement of the water body and the alleviation of eutrophication. For example, Ceratophyllum demersum, Myriophyllum spicatum, Potamogeton distinctus, or Hydrilla verticillata; the planting density is shown in Table 1;

[0045] Submerged plants Recommended planting density Ceratophyllum demersum <![CDATA[454 strains / m 3 > Myriophyllum spicatum <![CDATA[227 strains / m 3 > Vallisneria natans <![CDATA[227 strains / m 3 >

[0046] Table 1

[0047] Controlling the planting density range of submerged plants: The present invention recommends controlling the submerged plants at 200 - 500 plants / m 3 .

[0048] In the present invention, submerged plants are extremely important primary aquatic producers, an important source of carbon sinks, and also the key to alleviating eutrophication. Controlling the submerged plants at a certain density is beneficial to the utilization of water body nutrients and helps to stabilize the aquatic ecosystem. However, if the planting density of submerged plants is too large, resulting in intense population competition, it is instead not conducive to the stability of the ecosystem. The density of submerged plants should be determined according to the selected types of submerged plants as shown in Figure 2 , Figure 3 and Figure 4 ;

[0049] Controlling the biomass of phytoplankton: The present invention recommends controlling the phytoplankton below 10 μg / L.

[0050] In the aquatic ecosystem, especially in shallow lakes, there is often an inhibitory relationship of "one increases while the other decreases" between floating and submerged plants. For example, the relationship between floating and submerged plants discovered by the research group of the invention applicant in Caohai, Guizhou, as shown in Figure 5 . Excessive phytoplankton will lead to a decrease in water transparency, the degradation of submerged plants, and the transformation of the aquatic ecosystem from a clear lake dominated by submerged plants to a turbid lake dominated by phytoplankton. Therefore, it is recommended to control the floating density below 10 μg / L to ensure the dominant growth of submerged plants.

[0051] The partial pressure of CO2 in the water body of the aquatic ecosystem of the present invention reaches at least 570 ppm.

[0052] The main purpose of injecting CO2 in the present invention is:

[0053] Stimulate the photosynthesis of aquatic plants, achieve the effect of increasing the carbon sink of the water body, and change the competitive advantage of submerged - floating plants, thereby alleviating the effect of eutrophication.

[0054] In our previous research, it was found that there was a significant positive correlation between the dissolved inorganic carbon and the organic carbon sink in water bodies, that is, the more DIC, the greater the organic carbon sink, as Figure 6 shown. This is also the core mechanism of the present invention. Although the CO2 concentration conditions have not been optimized yet, judging from our previous experiments and research progress, CO2 has an obvious fertilization effect on the primary productivity, biomass and organic carbon content of aquatic ecosystems. Considering the economy of carbon sinks, it is recommended that the water body CO2 should be greater than 570 ppm, as Figure 7 shown.

[0055] The method of the present invention adjusts the molar ratio of CO2 / NO3 - > 50, and the molar ratio of CO2 / PO4 3- > 3000, as Figure 8 shown in FIGS. 10 to 11. This condition is beneficial to reducing the proportion of harmful algae, cyanobacteria, in phytoplankton and increasing the biomass of submerged plants, thus being beneficial to carbon sink enhancement and eutrophication mitigation.

[0056] The CO2 utilized by the method of the present invention includes, but is not limited to, the CO2 emitted industrially, and can also come from any direct or indirect method that may increase the CO2 in water bodies, such as increasing HCO3 - and CO3 2- in the water body and adjusting the pH to increase the CO2 concentration in the water body, or adjusting the land use type to increase the soil CO2 and then affecting the CO2 in groundwater and surface water, etc.

[0057] The above-described embodiments only represent the specific implementation manners of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the patent of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention.

Claims

1. A method for increasing the water body carbon sink and alleviating eutrophication by using industrial waste gas CO2, characterized in that, Including the following steps: Step 1: Cultivate an aquatic ecosystem with symbiotic floating and submerged plants; The aquatic ecosystem refers to an ecosystem composed of an aquatic biological community and a water environment; Step 2: Inject industrial waste gas CO2 into the water body of the aquatic ecosystem in Step 1 so that the CO2 partial pressure in the water body of the aquatic ecosystem reaches at least 570 ppm; Step 3: According to the nitrogen and phosphorus contents and ratios in the water body of the aquatic ecosystem in Step 1, adjust the CO2 injection amount and the nitrogen and phosphorus contents and ratios in the water body of the aquatic ecosystem in Step 2, so that the molar ratio of CO2 to NO3 - is greater than 50, and the molar ratio of CO2 to PO4 3- is greater than 3000; Step 4: While performing Step 3, adjust the community structure of floating or submerged plants.

2. The method for increasing the water body carbon sink and alleviating eutrophication by using industrial waste gas CO2 according to claim 1, characterized in that, Step 1 includes selecting submerged plant species, controlling the planting density range of submerged plants, and controlling the biomass of phytoplankton; the selection of submerged plant species is to select submerged plants that can repair eutrophication and utilize HCO3 in the water body - , and can utilize CO2; the planting density range of the submerged plants is controlled to be 200 - 500 plants / m 3 ; the biomass of the phytoplankton is controlled to be below 10 μg / L.

3. A method for increasing the water body carbon sink and alleviating eutrophication by using industrial waste gas CO2 according to claim 1, characterized in that, For Step 2, it is necessary to set the injection points of CO2 at different depths, positions and flow rates according to the water body's coverage area, water depth and flow rate; it is also necessary to adjust the daily injection time of CO2 according to the daily meteorological conditions including air temperature, rainfall, radiation intensity and wind speed as well as seasonal changes.

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