Carbon sink metering method and evaluation method for seaweed culture area

Abstract

The invention discloses a carbon sink metering method and evaluation method for a seaweed culture area, and the method comprises the steps: calculating the annual yield Ccap of atmospheric carbon in the seaweed culture area, the annual storage Cseq of inert carbon from seaweed and phytoplankton in the seaweed culture area, and the annual yield Char of seaweed biomass carbon; and obtaining the annual input quantity Cother of carbon in other ways in the seaweed culture area. According to the method, on the basis that the carbon sink function of a kelp culture sea area is derived from photosynthetic carbon sequestration of carbon-based organisms such as kelp and phytoplankton, the physiological and ecological characteristics of the carbon-based organisms are focused, the process that the carbon-based organisms drive atmospheric carbon to be captured, immobilized, mineralized, sealed and stored is taken as a main research line, and a seaweed culture carbon sink metering model is constructed from the angle of an ecological system; and each carbon library in the culture area is accurately quantified, the destination and destination of CO2 in the atmosphere are disclosed, and the effect of seaweed culture on relieving climatic change is evaluated in a real sense. The invention also discloses a carbon sink evaluation method for the seaweed culture area.

Description

Technical Field

[0001] The invention belongs to the field of fishery carbon sink measurement, and specifically refers to a carbon sink measurement method and an evaluation method for a seaweed cultivation area. Background Art

[0002] The ocean is the largest carbon pool on Earth. my country is not only a maritime power, but also a major fishery production country, and the scale of its seaweed farming ranks first in the world.

[0003] As a carbon-based organism, seaweed and its ecosystem are closely related to the biogeochemical process of carbon. 2 After being captured by seawater, the algae converts the CO dissolved in the seawater into 2 Converted into organic carbon, reducing water CO 2 partial pressure, breaking the carbon chemical balance of the water body and accelerating the atmospheric CO 2 It dissolves into seawater and, by harvesting the seaweed that has been converted into biomass carbon, is removed from the water, thus fulfilling the function of an ocean carbon sink.

[0004] As people's understanding of seaweed-mediated processes continues to deepen, in addition to the removable seaweed biomass carbon sink, the inert dissolved organic carbon pool formed by microorganisms during the growth of seaweed and the buried carbon pool in seafloor sediments are also important components of carbon sinks. 2 Flux is not enough. In fact, the key is not only to capture CO from the atmosphere 2 , attention should also be paid to its fate in the atmosphere, terrestrial or oceanic carbon pools, and its long-term storage on climate-relevant time scales.

[0005] Although seaweed farming is increasingly seen as an effective means of carbon removal and storage in many countries, proving the carbon removal and storage capacity of seaweed in marine systems is much more complicated than in terrestrial forests. 2 There is still much controversy over the removal effect of algae, which has also limited its entry into the carbon trading market. This is mainly because: (1) compared with trees, the turnover time of seaweed biomass carbon is shorter; (2) it is difficult to track the whereabouts of seaweed biomass carbon and algae-derived organic carbon and quantify where and how long it is stored; (3) seaweed photosynthesis fixes atmospheric CO dissolved in seawater 2 After, low CO 2 CO between seawater and atmosphere 2 There are differences in the time scales of rebalancing. At present, the scientific principles and process mechanisms of the carbon sink function of seaweed aquaculture are still facing great challenges. The methods and data for directly measuring carbon release and carbon sequestration are still insufficient, which poses a challenge to the accurate measurement of seaweed aquaculture carbon sinks and carbon sink trading. It is urgent to develop new carbon sink measurement theories and methods.

[0006] At present, the research on the carbon sink function of seaweed aquaculture only focuses on one or several specific processes in the carbon network driven by seaweed, resulting in deficiencies in the scientificity and systematicness of the supporting data of seaweed aquaculture carbon sinks, and the understanding of key processes and mechanisms. If the seaweed aquaculture area is regarded as a whole, focusing on the physiological and ecological characteristics of carbon-based organisms, and taking the atmospheric carbon capture-fixation-mineralization-storage processes driven by carbon-based organisms as the main research line, accurately quantifying the various carbon pools in the aquaculture area, and constructing a carbon sink measurement model for the seaweed aquaculture area from the ecosystem level, we can have a clearer understanding of the atmospheric CO 2 The destination and fate of kelp farming can be determined in a real sense, thereby evaluating the role of kelp farming in mitigating climate change. This will help carbon sink experts at home and abroad to recognize and accept the carbon sink function of seaweed farming.

[0007] Kelp is the main seaweed species cultivated in my country, and its scale and output rank first in the world. Therefore, the present invention takes kelp as a case to construct a carbon sink measurement and assessment method for seaweed cultivation areas, and uses kelp as a template to promote and apply this method to seaweed cultivation of other species and other regions. Summary of the invention

[0008] One of the purposes of the present invention is to provide a method for measuring carbon sinks in seaweed cultivation areas, which can accurately quantify the various carbon pools in seaweed cultivation areas, compare the difference between the atmospheric carbon capture and the ocean carbon sequestration in the cultivation areas, and use this as a basis for determining whether seaweed cultivation is a carbon sink or a carbon source.

[0009] This object of the present invention is achieved through the following technical solution: a carbon sink measurement method for seaweed cultivation areas, which is performed under the following four prerequisites:

[0010] (1) Biomass carbon with a fast carbon turnover time is not considered. The cultivated seaweed is basically an annual species. The present invention takes advantage of the fact that the annual production of seaweed in adjacent years is similar. The seaweed biomass carbon harvested in the current year is converted into CO in the atmosphere. 2 , which is considered to be the same as the amount of CO captured from the atmosphere by the seaweed farming area in the next year. 2 neutralize and offset;

[0011] (2) Quantify algae-derived inert carbon through long-term degradation simulation experiments. The large amount of organic carbon produced by seaweed during its growth, whether deposited on the seabed, retained in the seawater, or transported to the deep sea, will eventually be converted into inert carbon, thereby achieving long-term carbon sequestration in the ocean;

[0012] (3) CO entering seawater through sea-air exchange in seaweed cultivation areas 2 It can be regarded as the carbon source for seaweed photosynthesis. In seaweed cultivation areas, the CO between the atmosphere and the water2 Re-equilibrium times are usually short (days to weeks), allowing the atmosphere to fully replenish CO before the water body loses contact with the atmosphere. 2 The lack of water bodies, therefore the CO captured in the seaweed farming area 2 CO removed from the atmosphere 2 The ratio between them can be approximately considered to be 1:1;

[0013] (4) Carbon inputs to seaweed farming areas include atmospheric carbon capture and carbon inputs from other pathways. When assessing carbon sinks, their carbon transformation pathways are not distinguished, but rather the actual assessment is made of the joint driving forces of seaweed biocarbon harvesting and ocean carbon sequestration.

[0014] This measurement method constructs a carbon sink measurement model for seaweed farming areas at the ecosystem level. During the seaweed farming year, the seaweed farming area is regarded as an impenetrable black box, and the annual capture of atmospheric carbon, the annual storage of algae-derived inert carbon, and the annual harvest of seaweed biomass carbon outside the black box are calculated. The various carbon pools mediated by the farming area are accurately quantified. Based on the principle of carbon budget balance in the seaweed farming area, the annual input of carbon from other sources is calculated, which can provide a clearer understanding of the atmospheric CO 2 The whereabouts and fate of seaweed aquaculture can be determined in real terms to assess the role of seaweed aquaculture in mitigating climate change.

[0015] The carbon sink measurement model formula used in this measurement method is formula ①:

[0016] C cap +C other =C seN +C har Formula①

[0017] In the formula, C cap is the annual capture of atmospheric carbon in the seaweed farming area, in ta -1 , C seq is the annual storage of inert carbon from seaweed and phytoplankton in seaweed farming areas, in ta -1 , C har is the annual harvest of seaweed biomass carbon, in ta -1 , C other is the annual carbon input from other sources in the seaweed farming area, in ta -1 .

[0018] Furthermore, the carbon sink measurement method of the present invention comprises the following steps: continuously selecting 12 months covering a complete seaweed cultivation year, conducting sea survey sampling every month, and obtaining the sea-air interface CO 2The flux and seaweed growth conditions, including biomass carbon, shed carbon and decayed carbon of seaweed; according to the growth characteristics of seaweed, 12 months is divided into four stages: seaweed growth period, maturity period, aging period and non-seaweed cultivation period. In each stage, the carbon release of carbon-based organisms such as seaweed and phytoplankton and the carbon sequestration of algae-derived organic carbon are calculated through in situ release and indoor degradation experiments, including the inerting amount of released carbon of carbon-based organisms and the inerting amount of debris carbon.

[0019] In the present invention, the seaweed is kelp, and the sea-air interface CO 2 The flux was calculated by the following steps: the temperature and salinity of the surface seawater were measured using a portable water quality analyzer at the seaweed cultivation area, and the pH value of the surface seawater was measured using a precision portable pH meter. The surface seawater refers to the seawater 0.5 m below the surface. The surface seawater was collected using a 5L organic glass water sampler, 500mL of water sample was slowly filtered using a pretreated Whatman GF / F filter membrane, 50mL of the filtrate was stored in a pretreated brown glass bottle, and 5μL of saturated HgCl was quickly added. 2 The solution was sealed and stored at 4°C away from light. The total alkalinity (TA) was determined within 24 hours. The filter membrane was dried with neutral filter paper and stored at -20°C away from light for subsequent determination of chlorophyll a concentration. TA was determined using a total alkalinity titrator. Combined with temperature, salinity, pH value and TA data, the total alkalinity (TA) was determined using seawater CO 2 System calculation program software calculates surface sea water CO 2 Partial pressure (pCO 2 ); CO at the sea-air interface 2 The flux is calculated by formula ②,

[0020] F i =k i ×α i ×ΔpCO 2(i) Formula②

[0021] In the formula, F i is the sea-air interface CO2 in the seaweed cultivation area in month i 2 Flux, in mmol m -2 d -1 ;k i is the gas transmission rate of the sea-air interface in the seaweed cultivation area in month i, in cmh -1 ; α i is the CO of the seaweed cultivation area in month i 2 The solubility coefficient is in mol kg -1 ;ΔpCO 2(i) is the sea and air CO in the seaweed cultivation area in month i 2 Partial pressure difference, in μatm; atmospheric pCO 2The data can be downloaded from the website of the National Oceanic and Atmospheric Administration of the United States; The gas transfer rate k at the sea-air interface in the seaweed cultivation area in month i i Calculated by formula ③,

[0022] k i =0.266×u 10i 2 ×(Sc i / 660) -1 / 2 Formula③

[0023] In the formula, u 10i Wind speed at 10m above sea level, in ms -1 , which can be downloaded from the World Meteorological Organization website; Sc i is the Schmidt number of dissolved gas in the water of the seaweed cultivation area in the i-th month, which can be calculated by formula ④,

[0024] Sc i =2073.1-125.62×SST i +3.6276×SST i 2 -0.043219×SST i 3 Formula④

[0025] Where SST i is the surface seawater temperature in the seaweed farming area in month i, in °C.

[0026] CO 2 The solubility coefficient in seawater is calculated by formula ⑤,

[0027]

[0028] In the formula, SSS i is the salinity of surface seawater in the seaweed cultivation area in month i.

[0029] The annual atmospheric carbon capture in the seaweed cultivation area is calculated according to the following formula ⑥: cap ,

[0030]

[0031] Where S is the area of ​​seaweed cultivation area, unit is km 2 , measured by combining on-site GPS navigation with ArcGIS software, 30 is one month, unit is d, 12 is the molar mass of carbon, unit is g mol -1 .

[0032] In the present invention, the seaweed biomass carbon is obtained by regularly measuring the number of seaweed strains and biomass, as well as the carbon content of the tissue, i.e., formula ⑦ and formula ⑧,

[0033] B kelp-gro(i) =B kelp-ind(i) ×n i ×N formula⑦

[0034] C kelp-gro(i) =B kelp-gro(i) ×C kelp(i) ×DW kelp(i) Formula⑧

[0035] In the formula, B kelp-gro(i) is the net growth (wet weight) of seaweed in the culture area in month i, in t; B kelp-ind(i) is the biomass (wet weight) of a single seaweed plant in month i, in kg; n i is the number of seaweed individuals on each culture rope in the i-th month, in units of plants / roots; N is the number of culture ropes in the kelp culture system, in units of roots; C kekp-gro(i) is the amount of seaweed biomass carbon in the aquaculture area in month i, in tons; C kekp(i) is the tissue carbon content of cultured seaweed in month i, in g kg -1 ;DW kelp(i) It is the dry-to-wet ratio of kelp culture in the last month, unitless.

[0036] The amount of carbon shed by seaweed is calculated by formula ⑨ and formula ⑩.

[0037] B kelp-fall(i) =B kelp-ind(i) ×(n i-1 -n i )×N formula⑨

[0038]

[0039] In the formula, B kelP-fall(i) is the algae shed biomass (wet weight) in the culture area in month i, in t; (n i-1 -n i ) is the number of seaweed plants on each culture rope in month i compared to month (i-1), in plants / root; C kelp-fall It is the amount of carbon shed by seaweed during the cultivation period, in tons.

[0040] The amount of seaweed decay carbon is given by the formula and formula Calculate and obtain,

[0041]

[0042] In the formula, Rkelp-ero(i) is the seaweed decay rate in the aquaculture area in month i, in d -1 ; E max is the maximum decay rate of seaweed, and the value of kelp is 0.006d -1 ; P is the empirical coefficient corrected by the model, and the value of Laminaria japonica is 1.05; T opt is the optimum growth temperature for seaweed, and 12℃ for kelp; kelp-ero is the amount of carbon decayed by seaweed during the culture cycle, in tons; C kelp-debris is the carbon content of cultured seaweed debris, in g kg -1 .

[0043] The carbon content of phytoplankton biomass (or detritus carbon content) in the aquaculture area is expressed by the following formula: and formula Calculate and obtain,

[0044] C phyto(i) =C phyto-debris(i+1) =f×chl a i formula

[0045]

[0046] In the formula, C phyto(i) is the carbon content of phytoplankton biomass in the culture area in month i, or C phyto-debris(i+1) is the carbon content of phytoplankton debris in the (i+1)th month, in gm -3 ; f is the model constant, and its value varies from 25 to 250 in different sea areas; chl a i is the chlorophyll a concentration in the culture area in month i, in gm -3 ; C phyto is the amount of phytoplankton detritus carbon in the seaweed cultivation area in one year, in ta -1 ; E i is the true light layer depth of the water body in the aquaculture area in the i-th month, in meters, and is 3 times the transparency of seawater; τ i It is the residence time of phytoplankton in the euphotic zone in the culture area in the i-th month, in days.

[0047] The residence time of phytoplankton in the euphotic zone is obtained by: using the in-situ black and white bottle method to culture seawater for 4-6 hours, measuring the dissolved oxygen concentration in the water before and after the culture, and using the formula formula and formula Calculate the residence time of phytoplankton in the euphotic zone:

[0048]

[0049] Where, PP i is the primary productivity of surface phytoplankton in the seaweed cultivation area in month i, in mg C m -3 h -1 ;DO w0(i) and DO wt(i) are the dissolved oxygen concentrations in the white bottle water before and after the black and white bottle culture in the i-th month, DO B0(i) and DO Bt(i) are the dissolved oxygen concentrations of the black bottle water before and after the i-th month of cultivation, in mg L -1 ; V 1 is the volume of the black bottle and the white bottle, in L; T is the culture time, in h; β is the conversion coefficient of oxygen to carbon, with a value of 0.3; IPP i is the water column primary productivity of the seaweed cultivation area in month i, in mg C m -2 h -1 ;D i It is the daytime duration in the seaweed cultivation area in the ith month, in hours, and is usually 12 hours.

[0050] The amount of carbon released from the seaweed cultivation area was obtained in the following way: during the three stages of seaweed cultivation, 1-2 whole seaweeds were cultured in situ in enclosures as the seaweed treatment group, and the enclosure without seaweed was used as the control group; during the non-seaweed cultivation period, only the control group without seaweed was set up. The cultivation cycle was 24 hours, and the concentration of dissolved organic carbon (DOC) in the enclosure water before and after cultivation was measured. The amount of carbon released by seaweed and phytoplankton in the seaweed cultivation area was calculated using the formula Calculate and obtain,

[0051]

[0052] In the formula, C rel(i) is the carbon released by seaweed and phytoplankton in the seaweed cultivation area in month i, in tons; DOC 0(i) and DOC 24(i) are the water DOC concentrations at 0h and 24h of in situ enclosure culture in month i, in μmolL -1 d -1 ; V 2 It is the volume of the original impounded water body, in L.

[0053] The amount of carbon stored in seaweed debris was obtained through an indoor kelp debris degradation experiment. The specific operation process was as follows: cut seaweed tissue samples as seaweed debris, place the debris in an opaque barrel, and add a certain volume of natural seawater filtered through a 0.45μm filter membrane as the seaweed debris treatment group. At the same time, the barrel was only filled with the same volume of filtered seawater as the control group. All culture barrels were covered but not sealed and cultured in dark conditions for 365 days. At the beginning and end of the experiment, the DOC and POC concentrations in the water were measured.

[0054] The amount of carbon stored in seaweed debris is determined by the formula and formula Calculate and obtain,

[0055]

[0057] Where, %RC kelp-debris is the ratio of algae debris carbon converted to inert carbon, in %; OC t and OC c are the OC (DOC and POC) concentrations in the algae debris treatment group and the control group at the end of the degradation experiment, in mg L -1 ;D kelp-debris is the biomass density of algal debris, in g L -1 ; V kelp-debris C is the volume of water for kelp debris degradation and cultivation, in L; seq(kelp-debris) is the carbon sequestration of seaweed debris (falling off and decaying) in one year, in ta -1 .

[0058] The carbon sequestration capacity of phytoplankton debris was obtained through an indoor phytoplankton debris degradation experiment. The specific operation process is: select 3-5 dominant phytoplankton species in the seaweed farming area, mix them according to the quantitative ratio in the farming water, take the phytoplankton mixture, filter it through a GF / F glass fiber filter membrane (burned at 450℃ for 5h), collect the filter membrane, and determine the carbon content of the mixed phytoplankton. Then take the phytoplankton mixture and place it in an opaque culture bottle after cell disruption, and add a certain volume of natural seawater filtered through a 0.45μm filter membrane as the phytoplankton debris treatment group. At the same time, the culture bottle is only filled with the same volume of filtered seawater as the control group. All bottle mouths are covered with barrel mouths, but not sealed, and cultured in dark conditions for 30 days. At the beginning and end of the experiment, the DOC and POC concentrations in the water are measured. The carbon sequestration capacity of phytoplankton debris is obtained by the formula and formula Calculate and obtain,

[0059]

[0060] C seq(phyto-debris) =C phyto ×%RC phyto-debris formula

[0061] Where, %RC phyto-debris OC is the ratio of phytoplankton debris carbon converted to inert carbon, in %. t and OC care the OC (DOC and POC) concentrations in the phytoplankton debris treatment group and the control group at the end of the degradation experiment, in mg L -1 ; V 3 V is the volume of the mixed solution used to determine the carbon content of mixed phytoplankton, in L; 4 is the volume of phytoplankton mixture used for cell disruption, in L; C seq(phyto-debris) is the carbon sequestration amount of phytoplankton debris in one year, in ta -1 .

[0062] The amount of carbon sequestration released by seaweed and phytoplankton in the seaweed farming area was obtained through an indoor DOC degradation experiment. The specific operation process is: after the in-situ enclosure experiment is completed, the seaweed needs to be removed during the farming period, and all the water in the enclosure is quickly transported back to the laboratory, shaken and divided into opaque barrels, the barrel mouth is covered but not sealed, and a 365-day DOC degradation experiment is carried out under dark conditions. At the same time, natural seawater filtered through a 0.45μm filter membrane served as the control group. Each group was set up with 3 replicates. At the beginning and end of the experiment, the DOC concentration in the water body was measured. The amount of carbon sequestration released by seaweed and phytoplankton in the seaweed farming area is obtained by the formula formula and formula Calculation results:

[0063]

[0064] Where, %RC rel(cul) and %RC rel(non) The ratio of DOC released by seaweed and phytoplankton during seaweed farming and non-seaweed farming to inert carbon, in %; DOC cul(0) and DOC cul(t) are the degradation of DOC released by seaweed and phytoplankton during seaweed aquaculture, respectively. The DOC concentrations in the water before and after the experiment are in mg L -1 ;DOC non(0) and DOC non(t) are the DOC concentrations in the water before and after the experiment, respectively, in mg L -1 ; C seq(rel) is the amount of carbon sequestered by seaweed and phytoplankton released from seaweed farming areas in one year, in ta -1 .

[0065] The annual storage of inert carbon from seaweed and phytoplankton in the seaweed cultivation area is C seq Through the following formula get:

[0066] C seq =C seq(kekp-debris) +Cseq(phyto-debris) +C seq(rel) formula

[0067] The annual harvest of seaweed biomass carbon C har The data of the last month of seaweed cultivation is obtained by calculating the formula ⑧. For example, kelp is usually harvested in June, that is, the net growth (wet weight) of kelp in the eighth month is: C har =C kelp-gro(8) .

[0068] Annual atmospheric carbon capture in the seaweed farming areas that have been achieved C cap , the annual storage of inert carbon from seaweed and phytoplankton in seaweed farming areas C seq and the annual harvest of seaweed biomass carbon C har Based on the data, the annual carbon input from other sources in the seaweed farming area is calculated by formula ①: other .

[0069] The measurement method of the present invention is based on the fact that the carbon sink function of kelp culture sea areas originates from the photosynthetic carbon fixation of carbon-based organisms such as kelp and phytoplankton, focuses on the physiological and ecological characteristics of carbon-based organisms, and takes the process of atmospheric carbon capture-fixation-mineralization-storage driven by carbon-based organisms as the main research line. From the perspective of the ecosystem, a seaweed culture carbon sink measurement model is constructed to accurately quantify the various carbon pools in the culture area and reveal the atmospheric CO 2 The destination and fate of seaweed aquaculture can be evaluated in a real sense to mitigate climate change. This method (1) solves the controversial issue of seaweed biomass carbon. The seaweed biomass carbon harvested that year is converted into atmospheric CO 2 , which is considered to be the same as the amount of CO captured from the atmosphere by the seaweed farming area in the next year. 2 Neutralization and offset; (2) The research object and time scale of carbon sink measurement in aquaculture areas are clarified, which is not limited to aquaculture organisms and aquaculture stages, but should also include phytoplankton and non-aquaculture stages; (3) The difficulty of obtaining marine storage data of algal organic carbon is overcome. No matter where algal organic carbon is stored, it will eventually be degraded into inert carbon and stored for a long time; (4) Innovative carbon sink assessment indicators for aquaculture activities are created. By comparing the atmospheric carbon capture and carbon storage in aquaculture areas, it is assessed whether the atmospheric carbon captured in aquaculture areas can be completely stored in the ocean. The experimental operation techniques involved in this method are all routine operations in marine ecosystem research. The technical methods are mature, easy to operate, low in work intensity, low in economic cost, and easy to be widely promoted and applied.

[0070] A second object of the present invention is to provide a method for assessing carbon sinks in seaweed cultivation areas, which can be used to explain the assessment results.

[0071] This object of the present invention is achieved by the following technical solution: the method for evaluating the carbon sink measurement results of the seaweed cultivation area is adopted, and the judgment criteria of the evaluation method are as follows:

[0072] If the annual atmospheric carbon capture in the seaweed farming area is C cap >Annual storage of seaweed and phytoplankton in seaweed farming areas C seq , indicating that atmospheric CO 2 After entering and dissolving in the seaweed culture water, it is fixed by kelp and phytoplankton and converted into organic carbon, and part of the organic carbon is mineralized into CO 2 The gas returns to the atmosphere and cannot be completely locked away in the ocean, and the seaweed farming areas behave as a carbon source;

[0073] If the annual atmospheric carbon capture in the seaweed farming area is C cap <Annual storage of seaweed and phytoplankton in seaweed farming areas C seq , indicating that atmospheric CO 2 After entering and dissolving in the seaweed farming water, it is completely fixed by seaweed and phytoplankton and converted into organic carbon and stored in the ocean. The extra annual storage volume comes from other carbon input systems, such as carbon input from land runoff and offshore, and carbon release from respiratory calcification activities in the water. The seaweed farming area acts as a carbon sink.

[0074] If the annual atmospheric carbon capture in the seaweed farming area is C cap = Annual storage of seaweed and phytoplankton in seaweed farming areas C seq , indicating that atmospheric CO captured in the aquaculture area 2 After being fixed, migrated and transformed by seaweed and phytoplankton, they are sealed in the ocean, making the seaweed farming area carbon neutral.

[0075] Compared with the prior art, the present invention has the following significant effects:

[0076] (1) The present invention solves the controversial issue of seaweed biomass carbon. Cultivated seaweed is an annual species. The present invention takes advantage of the fact that the annual production of seaweed in adjacent years is similar. The seaweed biomass carbon harvested in the current year is converted into CO in the atmosphere. 2 , which is considered to be the same as the amount of CO captured from the atmosphere by the seaweed farming area in the next year. 2 Neutralize and offset.

[0077] (2) The present invention does not need to consider the difficulty of obtaining data during the burial and storage of carbon in sediments within the aquaculture system and its transportation to the deep sea for storage. In the aquaculture area, a large amount of organic carbon produced by seaweed and phytoplankton, whether buried in sediments, retained in seawater, or even transported to the deep sea, will eventually be converted into inert carbon to achieve long-term carbon storage in the ocean. The carbon sequestration of the present invention covers data such as sediments and deep sea that are usually easily overlooked and difficult to obtain, making the carbon sink measurement in seaweed aquaculture areas more scientific and accurate.

[0078] (3) This invention refers to the objective natural carbon input behaviors such as surface runoff, seawater exchange inside and outside the bay, groundwater discharge, respiratory calcification and mineralization as carbon input from other pathways other than atmospheric carbon capture. There are many challenges in directly calculating this part of carbon input. Therefore, this invention estimates the carbon input amount not captured by the atmosphere from the perspective of the ecosystem based on the carbon budget balance of the aquaculture area.

[0079] (4) The carbon input involved in the present invention includes atmospheric carbon capture and carbon input from other pathways. When evaluating the carbon sink function, the carbon transformation pathways of the two in the aquaculture area are not distinguished, and they jointly drive the seaweed biomass carbon harvesting and ocean carbon sequestration process.

[0080] (5) The field survey and indoor experimental methods involved in the present invention are routine operations for marine ecosystem research. The conditions and equipment required for these experiments can be achieved in general scientific research institutions and production units. The research methods are mature, easy to operate, low in labor intensity, and low in economic cost, which is convenient for wide promotion and application.

[0081] (6) The carbon sink measurement in the seaweed cultivation area involved in the present invention not only covers the seaweed cultivation period, but also includes the non-seaweed cultivation period. It is calculated based on one seaweed cultivation year, which reflects the comprehensiveness and completeness of the measurement method in terms of time scale.

[0082] (7) The carbon-based organisms in the seaweed aquaculture area involved in the present invention not only consider seaweed, but also phytoplankton, because the carbon sink function of the marine system begins with the photosynthetic carbon fixation of marine plants. At present, in the measurement and evaluation of the carbon sink function of aquaculture areas, usually only the aquaculture organisms themselves are focused on, while the important contribution of phytoplankton to the carbon sink in the sea area is ignored. At the same time, the carbon sink function of phytoplankton is also affected by the aquaculture organisms.

[0083] (8) The carbon sink measurement method for seaweed cultivation areas involved in the present invention realizes a paradigm shift from individualism to holism, using carbon-based organisms to drive atmospheric CO 2 The capture-fixation-mineralization-storage process is the main research line, and the comparative analysis of CO 2 Flux and its ocean carbon sequestration reveal atmospheric CO from an ecosystem perspective 2to truly assess the role of seaweed farming in mitigating climate change.

[0084] (9) The present invention calculates the carbon release of seaweed in detail. The carbon release during seaweed cultivation is greatly affected by its physiological state and environmental conditions. Therefore, the seaweed carbon release data of the present invention is divided into three different stages, namely, the kelp growth stage, the maturity stage and the aging stage, rather than simply using the data of a certain stage to represent the entire cultivation cycle, so that the carbon sink measurement data is more accurate and scientific.

[0085] (10) The measurement time involved in the present invention is calculated based on the annual seaweed cultivation period, rather than the conventional annual time period. Therefore, to facilitate statistical analysis, the present invention defines the starting month of measurement as the first month of seaweed seedling cultivation.

[0086] (11) The inertization ratio of phytoplankton debris carbon involved in the present invention is based on the types and proportions of dominant phytoplankton species in the aquaculture area, and is prepared into a phytoplankton mixed solution, which is then subjected to cell disruption treatment and then used in degradation experiments. The phytoplankton algae-derived debris obtained by this method can better reflect the actual characteristics of the site, thereby making the experimental data more authentic and reliable.

[0087] (12) The carbon sink measurement method of the seaweed cultivation system of the present invention further evaluates and interprets the results based on the accurate quantification of each carbon pool. If the annual capture of atmospheric carbon is greater than the annual storage of carbon-based organisms, it means that atmospheric CO 2 After entering and dissolving in the aquaculture water, it is fixed by carbon-based organisms such as seaweed and phytoplankton and converted into organic carbon, and part of the organic carbon is mineralized into CO 2 The gas returns to the atmosphere and cannot be completely stored in the ocean. The aquaculture area acts as a carbon source. If the annual capture of atmospheric carbon is less than the annual storage of carbon-based organisms, it means that atmospheric CO 2 After entering and dissolving in the aquaculture water, it is fixed and converted into organic carbon by carbon-based organisms such as seaweed and phytoplankton, and is completely sealed in the ocean. The extra annual storage volume comes from carbon input from other sources, such as carbon input from land runoff and offshore, and carbon release from respiratory calcification in water bodies. The aquaculture area then acts as a carbon sink. If the annual capture of atmospheric carbon = the annual storage volume of carbon-based organisms, it means that the atmospheric CO captured in the aquaculture area is 2 After the migration and transformation of carbon-based organisms such as seaweed and phytoplankton, it is sealed in the ocean, and the aquaculture area is carbon neutral. BRIEF DESCRIPTION OF THE DRAWINGS

[0088] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0089] Figure 1 It is a schematic diagram of the measurement results of each carbon pool in the carbon sink measurement model of the kelp culture area in Sanggou Bay of the present invention. DETAILED DESCRIPTION

[0090] This embodiment provides a carbon sequestration measurement method for the kelp culture area in Sanggou Bay, which comprises the following steps:

[0091] (1) Develop an experimental plan

[0092] According to the physiological characteristics of kelp growth and the time arrangement of aquaculture activities in Sanggou Bay, the kelp aquaculture year is divided into four stages: kelp growth period (November to March of the following year), maturity period (April to May), aging period (June) and non-kelp aquaculture period (July to October). Therefore, the starting month for carbon sink measurement in kelp aquaculture areas is November, and so on. 2 Flux, the survey frequency is once a month on the anniversary of kelp farming, or at least includes key months that can cover the above four stages and four seasons, such as January, April, June and October. At the same time, the field enclosure experiment obtains carbon release in the kelp farming area, and the survey selects one month in each of the three kelp farming periods, as well as July (or August) and September (or October) when it is not a kelp farming period.

[0093] (2) Marine ecological survey

[0094] The transparency of seawater was measured on site using a Secchi disk, and the temperature and salinity of the surface seawater were measured using a portable water quality analyzer. The surface seawater refers to the seawater 0.5 m below the surface. The pH value of the surface seawater was measured using a precision portable pH meter. The surface seawater was collected using a 5L organic glass water sampler, and 500mL of water sample was slowly filtered through a Whatman GF / F filter membrane. After the filtered filter membrane was dried with neutral filter paper, it was stored at -20°C away from light; 50mL of the filtrate was stored in a brown glass bottle, and 5μL of saturated HgCl was quickly added. 2 The solution was sealed and stored at 4°C away from light. The filter membrane was used to determine the chlorophyll a concentration, and the filtrate was used to determine TA. The kelp culture area in Sanggou Bay was determined to be about 80km by on-site GPS navigation and ArcGIS software. 2 .

[0095] (3) Kelp survey and sampling

[0096] Starting from November, 15 seedling ropes were marked and the number of kelp plants on each rope was measured regularly every month. At the same time, 3-5 kelp plants were randomly collected every month, their wet weight was measured on site, and then brought back to the laboratory, the algae were dried to constant weight, and the dry-wet ratio was measured. The dry tissue was ground and sieved, and the tissue carbon content was measured.

[0097] (4) In situ enclosure experiment

[0098] In situ enclosure culture was conducted on kelp and phytoplankton during the growth, maturity, senescence and non-kelp culture period. Only phytoplankton enclosure experiments were conducted during the non-kelp culture period. The enclosure was a cylindrical transparent polyethylene bag (2.0 m high and 0.6 m in diameter). During the culture process, the enclosure was filled with filtered seawater and the complete kelp fronds were suspended in the enclosure. The culture density was approximately 2 g L -1 (fresh weight), for the kelp group; the enclosure without kelp added is the phytoplankton group, all enclosures are fixed on the fish rack. During the culture period, the bag mouth is not tightened to prevent water exchange while maintaining sea-air exchange. The filtered seawater used for culture is the seawater from the kelp culture area filtered through a 20μm sieve silk to exclude the interference of large plankton and non-biological particles. Starting at 8 am every day and ending at 8 am the next day, water samples in the enclosure were taken at the beginning and end of the culture to determine the DOC concentration.

[0099] (5) In situ black and white bottle experiment

[0100] Select a black and white glass bottle with a volume of 200 mL, collect surface seawater to fill the bottle, seal it, and hang it in the surface water of the kelp culture area for 6 hours. Take water samples before and after cultivation to determine the dissolved oxygen concentration, and calculate the surface primary productivity and water column primary productivity.

[0101] (6) Indoor DOC degradation experiment

[0102] After the in-situ enclosure experiment, the kelp was taken out, and the water in the enclosures of the kelp group and the phytoplankton group was quickly transported back to the laboratory. After shaking, 20L of culture solution was divided into 25L light-proof drums, and the drum mouth was covered but not sealed. The DOC degradation experiment was carried out for 120 days under dark conditions. At the same time, natural seawater filtered through a 0.45 micron filter membrane was used as the control group. Three replicates were set for each group. At the beginning and end of the experiment, the DOC concentration in the water was measured.

[0103] (7) Indoor seaweed debris degradation experiment

[0104] Tissue samples (about 1-5 cm) were cut from the middle leaves of the kelp (about 5 cm from the petiole) (hereinafter referred to as "debris"). The debris was evenly distributed into 25-liter light-tight drums. The debris biomass density was about 3 g / L (fresh weight). 20 liters of natural seawater filtered through a 0.45-micron filter membrane was added to each drum as the debris group. At the same time, only 20 liters of filtered seawater was added to the drum as the control group. Three replicates were set up for each group. All culture drums were covered but not sealed and cultured in dark conditions for 365 days. At the beginning and end of the experiment, the DOC and POC concentrations in the water were measured.

[0105] (8) Indoor phytoplankton debris degradation experiment

[0106] The dominant phytoplankton species in three seaweed aquaculture areas were selected and mixed according to the number ratio in the aquaculture water body during the logarithmic growth period of phytoplankton. 50 mL of the phytoplankton mixture was taken and filtered through a GF / F glass fiber filter (burned at 450℃ for 5h), the filter membrane was collected, and the carbon content of the mixed phytoplankton was determined. Another 4L of the phytoplankton mixture was centrifuged and precipitated, the supernatant was discarded, and it was resuspended in 250mL of distilled water. After freeze-thaw cell disruption, it was placed in a 2L light-proof culture bottle and 1.5L of natural seawater filtered through a 0.45μm filter membrane was added as the phytoplankton debris treatment group. At the same time, the culture bottle was only filled with the same volume of filtered seawater as the control group. All bottle mouths covered the barrel mouth, but were not sealed, and cultured in dark conditions for 30 days. At the beginning and end of the experiment, the DOC and POC concentrations in the water body were measured.

[0107] (9) Index calculation

[0108] Based on data obtained from field surveys and laboratory tests, for example, seawater temperature, salinity, pH, total alkalinity, wind speed, atmospheric pCO 2 The monthly sea-air CO2 concentration in the kelp culture area of ​​Sanggou Bay was calculated using formulas ②-⑥. 2 The flux and atmospheric carbon capture data are shown in Table 1.

[0109] Table 1: Sea-air CO in kelp culture areas 2 Flux (mmol m -2 d -1 ) and atmospheric carbon capture (t) monthly data

[0110] time <![CDATA[Ocean-atmosphere CO 2 flux]]> Atmospheric carbon capture November -72.31 2082 December -64.70 1863 January -49.50 1425 February -57.10 1644 March -58.41 1682 April -59.72 1720 May -28.56 822 June -21.95 632 July -19.82 571 August 4.73 -136 September 16.71 -481 October -50.58 1457

[0111] Based on kelp survey sampling and laboratory testing, the kelp number, wet weight, dry weight, carbon content and breeding density were obtained using formula ⑥- The net carbon growth, carbon shedding and carbon decay of kelp were calculated. The monthly data of various biocarbon indicators of kelp in the kelp culture area of ​​Sanggou Bay are shown in Table 2.

[0112] Table 2: Monthly data of various biocarbon indicators of kelp in the Sanggou Bay kelp culture area (unit: t)

[0113] time Net Growth Carbon Carbon shedding amount Decayed carbon amount November 854 0 487 December 1784 58 674 January 4325 229 1320 February 12417 600 3716 March 17895 729 5936 April 20493 349 9402 May 28745 47 12336 June 31712 21 15790

[0114] Based on the in situ black and white bottle experiment and the obtained chlorophyll a concentration, the formula Calculate the amount of phytoplankton biomass carbon in the aquaculture area each month. The monthly data of phytoplankton biomass carbon in the kelp aquaculture area of ​​Sanggou Bay are shown in Table 3.

[0115] Table 3: Monthly data of phytoplankton biocarbon in the kelp culture area of ​​Sanggou Bay (unit: t)

[0116] month Phytoplankton biomass November 10 December 14 January 14 February 14 March 9 April 7 May 10 June 144 July 256 August 257 September 74 October 17

[0117] Based on in-situ enclosure experiments and indoor testing, the DOC concentration in the water before and after the experiment was obtained, and the transparency of the sea area was measured on site using a transparency disk. The carbon release in the sea area during the four stages of kelp growth, maturity, aging and non-cultivation was calculated. The monthly data of carbon release in the kelp cultivation area of ​​Sanggou Bay is shown in Table 4.

[0118] Table 4: Monthly data of carbon release from kelp and phytoplankton in the kelp culture area of ​​Sanggou Bay (unit: t)

[0119]

[0120] Based on the indoor DOC degradation experiment, the DOC concentration before and after the experiment was obtained, and based on the indoor debris degradation experiment, the DOC concentration and PC concentration before and after the experiment were obtained, and the formula was used to calculate the inerting ratio of DOC released from the kelp culture area and kelp debris and phytoplankton biocarbon. In addition, due to the long culture cycle of the degradation experiment, the inerting ratio here can also use the published data, for example, the inerting ratio of DOC released in the sea area during the kelp culture period is 58%, the inerting ratio of DOC released in the sea area during the non-kelp culture period is 33%, the inerting ratio of kelp debris carbon is 2.84%, and the inerting ratio of phytoplankton debris carbon is 4.8%.

[0121] According to formula ⑥, the annual capture of atmospheric carbon is 1.33×10 4 ta -1 ,

[0122] According to the formula and The annual carbon storage capacity of kelp debris in kelp culture areas is calculated to be 0.15×10 4 ta -1 ,

[0123] According to the formula and The annual storage capacity of phytoplankton detritus carbon in kelp culture areas is calculated to be 0.004×10 4 ta -1 ,

[0124] According to the formula and The annual carbon storage capacity released by kelp and phytoplankton during kelp cultivation is calculated to be 4.84×10 4 ta -1 ,

[0125] According to the formula and The annual carbon storage capacity of phytoplankton during the non-kelp culture period is calculated to be 0.63×104 ta -1 ,

[0126] According to the formula The annual carbon storage capacity of kelp culture area is calculated to be 5.63×10 4 ta -1 ,

[0127] According to formula ⑧, the annual harvest of kelp biomass carbon in kelp cultivation area is 3.17×10 4 ta -1 ,

[0128] According to formula ①, the annual carbon input from other sources in the kelp farming area is 7.47×10 4 ta -1 .

[0129] (7) Carbon sink assessment and analysis

[0130] According to the measurement results of each carbon pool above ( Figure 1 ), we found that the annual carbon sequestration in the kelp culture area of ​​Sanggou Bay (5.63×10 4 ta -1 ) is greater than the amount of carbon captured by the atmosphere (1.33×10 4 ta -1 ). This is based on the following two premises: (1) it does not distinguish between the fate of atmospheric captured carbon and carbon input from other pathways, and (2) the carbon in kelp biomass is converted into atmospheric CO 2 , which is considered to be the same as the CO captured from the atmosphere by the kelp farming area in the next year. 2 The measurement result can be explained by the capture of atmospheric CO2 driven by kelp farming in Sanggou Bay. 2 It can be completely stored in the ocean, and the extra carbon storage comes from carbon input from other sources. Therefore, the kelp farming area in Sanggou Bay is a carbon sink.

[0131] The above embodiments of the present invention are not intended to limit the protection scope of the present invention, and the implementation modes of the present invention are not limited thereto. All other modifications, replacements or changes made to the above structures of the present invention based on the above contents of the present invention, in accordance with common technical knowledge and customary means in the art, without departing from the above basic technical ideas of the present invention, should fall within the protection scope of the present invention.

Claims

1. A method for measuring carbon sinks in seaweed cultivation areas, characterized in that: This measurement method constructs a carbon sink measurement model for seaweed farming areas from the ecosystem level. During the seaweed farming year, the seaweed farming area is regarded as an impenetrable black box, and the annual capture of atmospheric carbon outside the black box, the annual storage of algae-derived inert carbon, and the annual harvest of seaweed biomass carbon are calculated. The various carbon pools mediated by the farming area are quantified. Based on the principle of carbon budget balance in the seaweed farming area, the annual input of carbon from other sources in the seaweed farming area is calculated. The carbon sink measurement model formula used in this measurement method is formula ①: C cap +C other =C seq +C har Formula① In the formula, C cap is the annual capture of atmospheric carbon in the seaweed farming area, in ta -1 , C seq is the annual storage of inert carbon from seaweed and phytoplankton in seaweed farming areas, in ta -1 , C har is the annual harvest of seaweed biomass carbon, in ta -1 , C other is the annual carbon input from other sources in the seaweed farming area, in ta -1 .

2. The method for measuring carbon sinks in seaweed cultivation areas according to claim 1, characterized in that: The measurement method includes the following steps: continuously selecting 12 months covering a complete seaweed cultivation year, conducting sea surveys and sampling every month to obtain the CO2 flux at the sea-air interface and the growth status of seaweed, the seaweed growth status includes the biomass carbon, shed carbon and decayed carbon of the seaweed; according to the growth characteristics of seaweed, the 12 months are divided into four stages: seaweed growth period, maturity period and aging period, and non-seaweed cultivation period. In each stage, the carbon release of carbon-based organisms such as seaweed and phytoplankton and the carbon sequestration of algae-derived organic carbon are calculated through in situ release and indoor degradation experiments, including the released carbon inerting amount of carbon-based organisms and the inerting amount of debris carbon.

3. The carbon sink measurement method for seaweed cultivation areas according to claim 2, characterized in that: The seaweed is kelp, and the CO2 flux at the sea-air interface is calculated by formula ②: F i =k i ×α i ×ΔpCO 2(i) Formula② In the formula, F i is the CO2 flux from the sea to the air interface in the seaweed cultivation area in month i, in mmolm -2 d -1 ;k i is the gas transmission rate of the sea-air interface in the seaweed cultivation area in month i, in cmh -1 ; α i is the solubility coefficient of CO2 in the seaweed cultivation area in month i, in molkg -1 ;ΔpCO 2(i) is the CO2 partial pressure difference between the sea and air in the seaweed cultivation area in month i, in μatm; atmospheric pCO2 data were downloaded from the website of the National Oceanic and Atmospheric Administration of the United States; the gas transfer rate k at the sea-air interface in the seaweed cultivation area in month i i Calculated by formula ③, k i =0.266×u 10i 2 ×(Sc i / 660) -1 / 2 Formula③ In the formula, u 10i Wind speed at 10m above sea level, in ms -1 , data downloaded from the World Meteorological Organization website; Sc i is the Schmidt number of dissolved gas in the water of the seaweed cultivation area in the i-th month, which can be calculated by formula ④, In the formula, SST i is the surface seawater temperature in the seaweed cultivation area in month i, in °C; Solubility coefficient of CO2 in seawater α i By calculating through formula ⑤, In the formula, SSS i is the salinity of the surface seawater in the seaweed cultivation area in month i; The annual atmospheric carbon capture in the seaweed cultivation area is calculated according to the following formula ⑥: cap , Where S is the area of ​​seaweed cultivation area, unit is km 2 , measured by combining on-site GPS navigation with ArcGIS software, 30 is one month, unit is d, 12 is the molar mass of carbon, unit is gmol -1 ; The seaweed biomass carbon is obtained by measuring the number of seaweed plants and biomass, as well as the carbon content of the tissues on a monthly basis, i.e., formula ⑦ and formula ⑧. B kelp-gro(i) =B kelp-ind(i) ×n i ×N formula⑦ C kelp-gro(i) =B kelp-gro(i) ×C kelp(i) ×DW kelp(i) Formula⑧ In the formula, B kelp-gro(i) is the net growth (wet weight) of seaweed in the culture area in month i, in t; B kelp-ind(i) is the biomass (wet weight) of a single seaweed plant in month i, in kg; n i is the number of seaweed individuals on each culture rope in the i-th month, in units of plants / roots; N is the number of culture ropes in the kelp culture system, in units of roots; C kelp-gro(i) is the amount of seaweed biomass carbon in the aquaculture area in month i, in tons; C kelp(i) is the tissue carbon content of cultured seaweed in month i, in gkg -1 ; DW kelp(i) is the dry-to-wet ratio of the last month of kelp culture, unitless; The amount of carbon shed by seaweed is calculated by formula ⑨ and formula ⑩. B kelp-fall(i) =B kelp-ind(i) ×(n i-1 -n i )×N formula⑨ In the formula, B kelp-fall(i) is the algae shed biomass (wet weight) in the culture area in month i, in t; (n i-1 -n i ) is the number of seaweed plants on each culture rope in month i compared to month (i-1), in plants / root; C kelp-fall is the amount of carbon shed by seaweed during the cultivation period, in t; The amount of carbon from decaying seaweed is expressed by the formula and formula Calculate and obtain, In the formula, R kelp-ero(i) is the seaweed decay rate in the aquaculture area in month i, in d -1 ; E max is the maximum decay rate of seaweed, and the value of kelp is 0.006d -1 ; P is the empirical coefficient corrected by the model, and the value of Laminaria japonica is 1.05; T opt is the optimum growth temperature for seaweed, and 12℃ for kelp; kelp-ero is the amount of carbon decayed by seaweed during the culture cycle, in t; C kelp-debris is the carbon content of cultured seaweed debris, in g kg -1 ; The amount of phytoplankton biomass carbon in the aquaculture area is calculated by the following formula: and formula Calculate and obtain, In the formula, C phyto(i) is the carbon content of phytoplankton biomass in the culture area in month i, or C phyto-debris(i+1) is the carbon content of phytoplankton debris in the (i+1)th month, in gm -3 ; f is the model constant, and its value varies from 25 to 250 in different sea areas; chla i is the chlorophyll a concentration in the culture area in month i, in gm -3 ; C phyto is the amount of phytoplankton detritus carbon in the seaweed cultivation area in one year, in ta -1 ; E i is the true light layer depth of the water body in the aquaculture area in the i-th month, in meters, and is 3 times the transparency of seawater; τ i is the residence time of phytoplankton in the euphotic zone in the culture area in month i, in days; The residence time of phytoplankton in the euphotic zone is obtained and the formula formula and formula Calculate the residence time of phytoplankton in the euphotic zone: Where, PP i is the primary productivity of surface phytoplankton in the seaweed cultivation area in month i, in mg C m -3 h -1 ;DO W0(i) and DO wt(i) are the dissolved oxygen concentrations in the white bottle water before and after the black and white bottle culture in the i-th month, DO B0(i) and DO Bt(i) are the dissolved oxygen concentrations of the black bottle water before and after the i-th month of cultivation, in mg L -1 ; V1 is the volume of the black bottle and the white bottle, in L; T is the culture time, in h; β is the conversion coefficient of oxygen to carbon, with a value of 0.3; IPP i is the water column primary productivity of the seaweed cultivation area in month i, in mgCm -2 h -1 ; D i is the daytime duration in the seaweed cultivation area in month i, in h, with a value of 12h; The carbon released by seaweed cultivation areas was obtained by using the formula Calculate and obtain, In the formula, C rel(i) is the carbon released by seaweed and phytoplankton in the seaweed cultivation area in month i, in tons; DOC 0(i) and DOC 24(i) are the water DOC concentrations at 0h and 24h of in situ enclosure culture in month i, in μmolL -1 d -1 ; V2 is the volume of the original enclosure, in L; The amount of carbon stored in seaweed debris was obtained through an indoor kelp debris degradation experiment. The amount of carbon stored in seaweed debris was calculated using the formula and formula Calculate and obtain, Where, %RC kelp-debris is the ratio of algae debris carbon converted to inert carbon, in %; OC t and OC c are the OC (DOC and POC) concentrations in the algae debris treatment group and the control group at the end of the degradation experiment, in mg L -1 ;D kelp-debris is the biomass density of algal debris, in g L -1 ; V kelp-debris C is the volume of water for kelp debris degradation and cultivation, in L; seq(kelp-debris) is the amount of carbon sequestered by algal debris that falls off and decays in one year, in ta -1 ; The carbon sequestration amount of phytoplankton debris was obtained through the indoor phytoplankton debris degradation experiment. The carbon sequestration amount of phytoplankton debris was obtained through the formula and formula Calculate and obtain, Where, %RC phyto-debris OC is the ratio of phytoplankton debris carbon converted to inert carbon, in %. t and OC c are the concentrations of DOC and POC in the phytoplankton debris treatment group and the control group at the end of the degradation experiment, respectively, in mg L -1 ; V3 is the volume of the mixed solution used to determine the carbon content of the mixed phytoplankton, in L; V4 is the volume of the phytoplankton mixed solution used for cell disruption, in L; C seq(phyto-debris) is the carbon sequestration amount of phytoplankton debris in one year, in ta -1 ; The amount of carbon sequestration released by seaweed and phytoplankton in the seaweed cultivation area was obtained through indoor DOC degradation experiments, and the amount of carbon sequestration released by seaweed and phytoplankton in the seaweed cultivation area was obtained through the formula formula and formula Calculation results: Where, %RC rel(cul) and %RC rel(non) The ratio of DOC released by seaweed and phytoplankton during seaweed farming and non-seaweed farming to inert carbon, in %; DOC cul(0) and DOC cul(t) are the degradation of DOC released by seaweed and phytoplankton during seaweed aquaculture, respectively. The DOC concentrations in the water before and after the experiment are in mg L -1 ; DOC non(0) and DOC non(t) are the DOC concentrations in the water before and after the experiment, respectively, in mg L -1 ; C seq(rel) is the amount of carbon sequestered by seaweed and phytoplankton released from seaweed farming areas in one year, in ta -1 ; The annual storage of inert carbon from seaweed and phytoplankton in the seaweed cultivation area is C seq Through the following formula get: The annual harvest of seaweed biomass carbon C har The data of the last month of seaweed cultivation is obtained by calculating the formula ⑧. At this time, C har =C kelp-gro(8) ; Annual atmospheric carbon capture in the seaweed farming areas that have been achieved C cap , the annual storage of inert carbon from seaweed and phytoplankton in seaweed farming areas C seq and the annual harvest of seaweed biomass carbon C har Based on the data, the annual carbon input from other sources in the seaweed farming area is calculated by formula ①: other .

4. The method for measuring carbon sinks in seaweed cultivation areas according to claim 3, characterized in that: The calculation of the CO2 flux at the sea-air interface is obtained by the following steps: using a portable water quality analyzer to measure the temperature and salinity of the surface seawater in the seaweed cultivation area, and using a portable pH meter to measure the pH value of the surface seawater, the surface seawater refers to the seawater 0.5m underwater; using a 5L organic glass water sampler to collect the surface seawater, taking 500mL of water sample and filtering it with a pretreated Whatman GF / F filter membrane, 50mL of the filtrate is stored in a pretreated brown glass bottle, 5μL of saturated HgCl2 solution is added dropwise, the bottle is sealed, and stored at 4°C in the dark, and the total alkalinity is determined within 24 hours; the filtered filter membrane is dried with neutral filter paper, and then stored at -20°C in the dark for subsequent determination of chlorophyll a concentration; TA is determined using a total alkalinity titrator; combining temperature, salinity, pH value and TA data, the CO2 partial pressure in the surface sea water area is calculated using the seawater CO2 system calculation program software.

5. The method for measuring carbon sinks in seaweed cultivation areas according to claim 3, characterized in that: The residence time of phytoplankton in the euphotic zone is obtained by: using the in-situ black and white bottle method to culture seawater for 4-6 hours, measuring the dissolved oxygen concentration in the water before and after the culture, and using the formula formula and formula Calculate the residence time of phytoplankton in the euphotic zone.

6. The method for measuring carbon sinks in seaweed cultivation areas according to claim 3, characterized in that: The amount of carbon released by the seaweed cultivation area is obtained by the following method: in the three stages of seaweed cultivation, 1-2 complete seaweeds are cultured in situ in enclosures as the seaweed treatment group, and the enclosure without seaweed is used as the control group; during the non-seaweed cultivation period, only the control group without seaweed is set up; the cultivation cycle is 24 hours, and the dissolved organic carbon concentration in the enclosure water before and after cultivation is measured, and the formula is used Obtained by calculation.

7. The method for measuring carbon sinks in seaweed cultivation areas according to claim 3, characterized in that: The amount of carbon stored in seaweed debris is obtained through an indoor kelp debris degradation experiment. The specific operation process is: cut seaweed tissue samples as seaweed debris, place the debris in an opaque barrel, add natural seawater filtered by a 0.45μm filter membrane, and serve as a seaweed debris treatment group; at the same time, the barrel is filled with only the same volume of filtered seawater as a control group; all culture barrels are covered but not sealed, and cultured in dark conditions for 365 days; at the beginning and end of the experiment, the DOC and POC concentrations in the water are measured; the amount of carbon stored in seaweed debris is calculated by the formula and formula Obtained by calculation.

8. The method for measuring carbon sinks in seaweed cultivation areas according to claim 3, characterized in that: The carbon sequestration amount of phytoplankton debris is obtained through an indoor phytoplankton debris degradation experiment. The specific operation process is: select 3-5 dominant phytoplankton species in the seaweed cultivation area, mix them according to the quantity ratio in the cultivation water body, take the phytoplankton mixture, filter it through a GF / F glass fiber filter membrane, collect the filter membrane, and determine the carbon content of the mixed phytoplankton; then take the phytoplankton mixture, after cell crushing, place it in an opaque culture bottle, add natural seawater filtered through a 0.45μm filter membrane, as a phytoplankton debris treatment group; at the same time, the culture bottle is only filled with the same volume of filtered seawater as a control group; all bottle mouths are covered with barrel mouths, but not sealed, and cultured in dark conditions for 30 days; at the beginning and end of the experiment, the DOC and POC concentrations in the water body are determined; the carbon sequestration amount of phytoplankton debris is calculated by the formula and formula Obtained by calculation.

9. The method for measuring carbon sinks in seaweed cultivation areas according to claim 3, characterized in that: The amount of carbon sequestration released by seaweed and phytoplankton in the seaweed cultivation area is obtained through an indoor DOC degradation experiment. The specific operation process is: after the in-situ enclosure experiment is completed, the seaweed needs to be removed during the cultivation period, and all the water in the enclosure is quickly transported back to the laboratory, shaken and divided into opaque barrels, the barrel mouth is covered but not sealed, and a 365-day DOC degradation experiment is carried out under dark conditions; at the same time, natural seawater filtered through a 0.45μm filter membrane is used as the control group; 3 replicates are set for each group; at the beginning and end of the experiment, the DOC concentration in the water body is measured; the amount of carbon sequestration released by seaweed and phytoplankton in the seaweed cultivation area is obtained by the formula formula and formula Obtained by calculation.

10. A method for evaluating the carbon sink measurement results of seaweed cultivation areas according to any one of claims 1 to 9, wherein the criteria for the evaluation method are as follows: If the annual atmospheric carbon capture in the seaweed farming area is C cap >Annual storage of seaweed and phytoplankton in seaweed farming areas C seq This indicates that after atmospheric CO2 enters and dissolves in seaweed farming water, it is fixed by kelp and phytoplankton and converted into organic carbon. Some organic carbon will be mineralized as CO2 gas and return to the atmosphere, and cannot be completely sealed in the ocean. The seaweed farming area acts as a carbon source. If the annual atmospheric carbon capture in the seaweed farming area is C cap <Annual storage of seaweed and phytoplankton in seaweed farming areas C seq , indicating that after atmospheric CO2 enters and dissolves in seaweed farming water, it is completely fixed by seaweed and phytoplankton and converted into organic carbon and stored in the ocean. The extra annual storage volume comes from other carbon input systems, and the seaweed farming area acts as a carbon sink. If the annual atmospheric carbon capture in the seaweed farming area is C cap = Annual storage of seaweed and phytoplankton in seaweed farming areas C seq This shows that the atmospheric CO2 captured in the aquaculture area is fixed, migrated and transformed by seaweed and phytoplankton and is then stored in the ocean, making the seaweed aquaculture area carbon neutral.

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