System and method for monitoring and evaluating carbon and nitrogen burial rate of sandy river reservoir

Abstract

The invention relates to the technical field of water ecological environment, in particular to a sandy river reservoir carbon and nitrogen burial rate monitoring and evaluating system and method.According to the method, the variable quantity of the height of a sedimentary layer is regularly measured, the sedimentary layer is sampled at a plurality of sampling points, and the content of carbon and nitrogen in a sedimentary layer sample is measured; according to the method, the burying rate of the greenhouse gas elements of each sampling point is calculated in combination with the sampling period and the deposition layer updating amount, and then the overall burying rate of the reservoir is comprehensively estimated through the burying rates of the greenhouse gas elements of the multiple sampling points at multiple sampling moments, so that the dynamic and accurate monitoring of the carbon and nitrogen burying process is realized; and a reliable basis is provided for the subsequent evaluation of the total carbon and nitrogen burial potential of the reservoir and the quantitative evaluation of the influence of the reservoir on the greenhouse gas circulation process.

Description

Technical Field

[0001] This invention relates to the field of aquatic ecological environment technology, specifically to a system and method for monitoring and assessing the carbon and nitrogen burial rate in reservoirs of sandy rivers. Background Technology

[0002] With the intensification of global warming, controlling greenhouse gas emissions has become a hot topic in the energy sector, leading to the rapid development of various clean energy sources. Hydropower, as a clean and renewable energy source, is also highly anticipated. However, the construction of reservoirs inevitably inundates land, impounds water flow, and intercepts large amounts of sediment. Coupled with the effect of "in-channel" reactors, this hinders the flow of nutrients, increasing their residence time in the terrestrial-oceanic aquatic continuum (LOAC). This inevitably alters the carbon exchange relationship between the original regional ecosystem and the atmosphere, leading to controversy regarding whether hydropower can effectively reduce greenhouse gas emissions. Since the 1990s, studies have shown that reservoir construction may increase the release flux of CH4 and CO2. Therefore, understanding how reservoirs affect the biogeochemical cycle of greenhouse gases in the LOAC has become a crucial aspect of hydropower construction. Among these factors, carbon and nitrogen burial during reservoir sediment deposition is a key link affecting the reservoir's carbon and nitrogen cycle, and accurate monitoring of its rate is essential for scientifically assessing the reservoir's carbon source / sink function. Summary of the Invention

[0003] To accurately assess the carbon and nitrogen burial rate and potential of reservoirs, this application provides a system and method for monitoring and assessing the carbon and nitrogen burial rate of reservoirs in sediment-rich rivers. The method includes the following steps:

[0004] Obtain the sediment layer update amount, which is the difference between the sediment layer height at the current sampling time and the sediment layer height at the previous sampling time;

[0005] Sedimentary samples were obtained from multiple sampling points within the reservoir area. New sediment samples were extracted based on the amount of sedimentary renewal, and the content of greenhouse gas elements in each new sediment sample was determined.

[0006] The burial rate of greenhouse gas elements at each sampling point is calculated based on the sampling period, the amount of sediment renewal at each sampling point, and the content of greenhouse gas elements.

[0007] The overall greenhouse gas burial rate of the reservoir is estimated based on the greenhouse gas burial rates of all sampling points obtained at multiple sampling times.

[0008] The system provided in this application includes:

[0009] The sedimentary layer measurement unit is used to measure the height of the sedimentary layer and calculate the amount of sedimentary layer renewal based on the change in sedimentary layer height.

[0010] The sedimentary layer sampling unit is used to acquire sedimentary layer samples from sampling points and to extract new sediment samples based on the amount of sedimentary layer renewal.

[0011] The elemental content determination unit is used to measure the content of greenhouse gas elements in new sediment samples;

[0012] The burial rate calculation unit is used to calculate the greenhouse gas burial rate of each sampling point based on the greenhouse gas element content, sediment layer renewal rate and sampling cycle, and to calculate the overall greenhouse gas element burial rate of the reservoir based on the greenhouse gas burial rates of all sampling points.

[0013] The technical effects and advantages of the invention are as follows: By periodically measuring changes in sediment layer height and carbon and nitrogen content within the sediment layer, and combining this with the sampling cycle and sediment layer renewal rate, the burial rate of greenhouse gases at each sampling point is calculated. Furthermore, by comprehensively estimating the overall burial rate of the reservoir using data from multiple sampling times and points, dynamic and precise monitoring of the carbon and nitrogen burial process is achieved. This provides a reliable basis for subsequent assessments of the overall carbon and nitrogen burial potential of the reservoir and for quantitatively evaluating the reservoir's impact on the greenhouse gas cycle. Attached Figure Description

[0014] Figure 1 This is an overall flowchart of the method provided in the embodiments of the present invention.

[0015] Figure 2 This is a schematic diagram illustrating one implementation method of sampling point arrangement in an embodiment of the present invention.

[0016] Figure 3 This is a schematic diagram illustrating one implementation method of sampling point arrangement in an embodiment of the present invention.

[0017] Figure 4 This is a schematic diagram of the overall structure of the system provided in an embodiment of the present invention. Detailed Implementation

[0018] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] The main greenhouse gases in the Earth's atmosphere include water vapor, carbon dioxide, nitrous oxide (pressure nitrogen oxide), Freon, and methane. The main reason for the impact of human activities on global warming is the dramatic increase in carbon dioxide emissions. Therefore, carbon emissions are currently the main indicator for controlling greenhouse gas emissions internationally.

[0020] There are two main mechanisms for carbon sequestration in reservoirs: one is the input and deposition of organic carbon. For example, runoff carries dissolved organic carbon (DOC), particulate organic carbon (POC), and biomass residues from the soil into the reservoir. This carbon is deposited at the bottom of the reservoir along with sediment. Additionally, algae and aquatic plants in the reservoir absorb carbon dioxide and convert it into organic carbon through photosynthesis. After these organisms die, they also deposit at the bottom of the reservoir and are preserved in the sedimentary layer over a long period. The other mechanism is the precipitation of inorganic carbonates. Under specific conditions (such as increased pH or algal activity), dissolved inorganic carbon in the water can form calcium carbonate precipitates, which then sequester the carbon in the sedimentary layer.

[0021] On the other hand, biological activities in reservoir ecosystems not only affect atmospheric carbon dioxide but also significantly influence nitrous oxide concentrations. Some organisms can absorb and fix atmospheric nitrogen (e.g., legumes use rhizobia to fix nitrogen), thus reducing nitrous oxide levels in the reservoir area. However, when these organisms die, some microorganisms release nitrous oxide during decomposition. This is especially true during the flood season when rapid rises in reservoir water levels lead to the death of large numbers of aquatic plants, or when upstream flood peaks carry large amounts of nutrients into the reservoir, increasing microbial decomposition and causing a rapid increase in nitrous oxide concentrations.

[0022] Therefore, this application assesses the impact of reservoirs on changes in greenhouse gas concentrations by evaluating the carbon and nitrogen burial rates of the reservoirs.

[0023] Based on the above analysis, embodiments of the present invention provide a method for monitoring and assessing the carbon and nitrogen burial rate in reservoirs of sandy rivers, with reference to... Figure 1 This includes the following steps:

[0024] S1. Obtain the sediment layer update amount, which is the difference between the sediment layer height at the current sampling time and the sediment layer height at the previous sampling time.

[0025] S2. Obtain sediment samples from multiple sampling points within the reservoir area, extract new sediment samples based on the amount of sediment renewal, and determine the content of greenhouse gas elements in each new sediment sample.

[0026] S3. Calculate the greenhouse gas element burial rate of each sampling point based on the sampling period, the amount of sediment layer renewal at each sampling point, and the greenhouse gas element content.

[0027] S4. Estimate the overall greenhouse gas burial rate of the reservoir based on the greenhouse gas burial rates of all sampling points obtained at multiple sampling times.

[0028] Specifically, in step S1, the amount of deposition layer renewal can be obtained through the following steps:

[0029] S11. Set up multiple sampling points in multiple different areas of the reservoir area, and use a gravity column sampler or box sampler to obtain sediment layer samples at each sampling point, and measure the sediment layer height of the sediment layer samples.

[0030] S12. Subtract the sedimentation height of the sedimentation sample obtained at the previous sampling time from the sedimentation height obtained at the current sampling time, and use the absolute value of the difference as the sedimentation update amount.

[0031] When setting up sampling points, they should be located in representative areas of sandy rivers and reservoirs, such as... Figure 2 As shown, the sampling points should be strategically placed according to factors such as the hydrological characteristics of different areas of the reservoir (e.g., the inflow area, the central reservoir area, and the dam-front area), topographic conditions (e.g., deep-water sedimentation areas, reservoir-side wetlands, and shallow-water sedimentation areas), differences in sediment load, and the degree of human impact, to ensure that the sampling points reflect the overall sedimentary conditions of the reservoir. For example, the sampling point density can be appropriately increased in the inflow area to capture the sedimentary characteristics of river-injected sediment; in the central reservoir area, areas with relatively stable water flow and sedimentary environment should be selected as sampling points; and in the dam-front area, the impact of reservoir operation on the sedimentary layers must be considered.

[0032] In practice, fixed-point samplers can be used. This allows for control over the sampler's depth during each sampling, penetrating recent sedimentary layers and reaching relatively stable geological strata to ensure sufficient sedimentary sequence information for subsequent calculations of sedimentary regeneration. Furthermore, since the sampler's altitude is fixed and known, the height of newly formed sedimentary layers can be calculated based on the height of the sampled sedimentary layers. Alternatively, a floating sampling method can be employed, such as using a ship to travel to the sampling point, obtain sedimentary samples, calculate the sedimentary layer height based on the current water level of the reservoir, and then calculate the sedimentary regeneration amount.

[0033] In some embodiments, for newly constructed reservoirs or those in the planning stage, it is difficult to establish sampling points based on sedimentary characteristics because the reservoir's sedimentary layer morphology has not yet formed a stable structure or is unknown. This is especially true for reservoirs located in sediment-rich river basins, where sedimentary layers change rapidly. For example, the Sanmenxia and Xiaolangdi reservoirs in the Yellow River basin not only require regular water and sediment regulation, but also experience drastic changes in the sedimentary layers within the reservoir area, and water levels fluctuate significantly due to seasonal variations. Fixed sampling points either fail to cover the entire representative area, or some sampling points become ineffective (no water, no sediment) during certain periods of the year.

[0034] To address this issue, acoustic methods can be used to obtain the amount of sediment renewal, specifically including the following steps:

[0035] S13. Based on the characteristics of the inflow, multiple sonar scanning paths are preset, and acoustic detection methods such as side-scan sonar are used to obtain the surface data of the sedimentary layer at the current sampling time. These surface data of the sedimentary layer can reflect the height of the uppermost layer of the sedimentary layer in the entire reservoir area, so that a three-dimensional model of the entire sedimentary layer can be constructed and the latest height of the sedimentary layer at each location can be accurately obtained.

[0036] S14. After completing the scanning of the reservoir area, project the surface data of the sedimentary layer of the entire reservoir area onto a preset grid, such as... Figure 3 As shown, the amount of sediment update at each preset grid node is calculated based on the sediment surface data obtained at the previous sampling time.

[0037] Specifically, within the reservoir area, multiple sonar scanning paths should be scientifically planned and deployed, taking into account factors such as reservoir morphology, water flow direction, source of sediment, and general patterns of past sedimentary changes. These paths should cover the entire reservoir area as evenly as possible, with particular attention paid to areas where sedimentary changes may be significant, such as the reservoir tail, the main flow area in the middle of the reservoir, and the distributaries. The number and spacing of the scanning paths need to be adjusted according to the actual size and complexity of the reservoir. For large and complex reservoirs, the number of scanning lines can be increased and the spacing reduced, while for small reservoirs, the approach can be simplified accordingly.

[0038] The advantages of using acoustic methods to obtain sedimentary regeneration data are as follows: Traditional gravity-based columnar samplers require pressure to insert into the sedimentary layer, which is relatively easy in shallow water but much more difficult in deep water. Acoustic methods, however, can penetrate water, enabling non-contact measurement of underwater sedimentary layers without the need for traditional drilling, thus reducing sampling difficulty. Furthermore, sonar equipment can quickly acquire sedimentary layer data over large areas, offering higher efficiency and wider coverage compared to single-point drilling, allowing for a rapid scan of the entire reservoir's sedimentary layers. In addition, acoustic measurements have high resolution and accuracy, clearly reflecting changes in sedimentary layer thickness, distribution characteristics, and internal structure, providing reliable data for accurately calculating sedimentary regeneration. This method also offers good continuity and repeatability, facilitating long-term dynamic monitoring of sedimentary layer evolution and providing effective technical support for assessing reservoir carbon and nitrogen burial rates.

[0039] In some embodiments, the sampling time can be determined by a fixed period during the process of obtaining the amount of sediment layer updates. For example, in daily monitoring, the sediment layer can be sampled or scanned on a fixed basis every day or month to monitor changes in the sediment layer in a timely manner.

[0040] However, certain special hydrological events can cause drastic fluctuations in sedimentary layers within a short period, such as flood peaks and sediment regulation during the rainy season. Using a fixed sampling period to determine sampling times may prevent timely acquisition of the impact of these special hydrological events on the sedimentary layers. Especially in the current context of drastic climate change, with the increase in extreme weather events, the probability and frequency of special hydrological events have become greater. This makes traditional fixed-period sampling methods insufficient to comprehensively capture the dynamic changes in sedimentary layers, potentially missing key depositional or erosion events, thus affecting the accuracy and timeliness of carbon and nitrogen burial rate assessments. Therefore, in actual monitoring, in addition to conventional fixed-period sampling, it is necessary to combine meteorological and hydrological early warning information and increase the sampling frequency before, during, and after anticipated special hydrological events (such as heavy rainfall, floods, and reservoir discharge and sediment regulation) to fully record the changes in sedimentary layers before and after the event, providing more comprehensive data support for accurately assessing the dynamic changes in carbon and nitrogen burial rates. For example, when the meteorological department issues a blue or higher rainstorm warning, the monitoring system can automatically trigger a temporary sampling plan. The first encrypted sampling will be initiated within 24 hours after the warning is issued, and then sampling will be conducted every 12 hours until the flood peak passes and the water level falls below the warning level and returns to normal. Then, a final sampling will be conducted 48 hours later to construct a sequence of sedimentary layer changes under the influence of special hydrological events.

[0041] Specifically, in step S2, when the amount of sediment renewal is obtained by acoustic means, the determination of the sampling points of the sediment layer can be dynamically adjusted according to the amount of sediment renewal, which specifically includes the following steps:

[0042] S21. Establish a deposition rate distribution model based on the obtained deposition layer update amount, calculate the deposition rate at each preset grid node, and when the deposition rate is greater than the deposition rate threshold, use this preset grid node as the sampling point of the deposition layer. The deposition rate is the ratio of the deposition layer update amount obtained from two adjacent samplings to the sampling period.

[0043] The density of the preset grid can be determined based on the deposition rate. For areas with high deposition rates, a higher density preset grid can be set to improve the spatial resolution of sampling points, thereby more accurately capturing subtle changes in the sedimentary layer. Conversely, for areas with low deposition rates or virtually no deposition, the preset grid density can be appropriately reduced to minimize unnecessary sampling costs and data redundancy while ensuring monitoring effectiveness. Furthermore, the boundary of the preset grid can be dynamically delineated based on the actual water area of ​​the reservoir, topographic features, and historical sedimentary distribution to ensure effective coverage of all areas where significant depositional activity may occur.

[0044] Specifically, in step S2, the determination of the greenhouse gas element content in the new sediment sample includes the following steps:

[0045] S22. Dry the new sediment sample;

[0046] S23. A small amount of fresh sediment sample after drying is completely burned in a high-temperature (greater than 950°C) oxygen-rich environment to oxidize all carbon into carbon dioxide.

[0047] S24. The local carbon content in the new sediment sample is determined by chromatographic column analysis and quantitative analysis using a thermal conductivity detector or infrared detector. The carbon content in the new sediment sample is obtained based on the ratio of the mass of the new sediment sample that participated in the combustion to the local carbon content.

[0048] After obtaining sedimentary layer samples using columnar or box samplers, the amount of sedimentary layer renewal can be used to determine which sedimentary layers in the obtained sedimentary layer samples are newly deposited, thus identifying new sediment samples.

[0049] The same method can be used to confirm the nitrogen content. The dried new sediment sample is completely burned at high temperature to convert nitrogen into nitric oxide. Then, the local nitrogen content is determined by column chromatography, thereby determining the nitrogen content in the new sediment sample.

[0050] Specifically, in step S3, after obtaining the greenhouse gas element content in the new sediment sample through the above steps, the greenhouse gas element burial rate at each sampling point can be calculated based on the deposition rate:

[0051]

[0052] In the formula, This represents the amount of carbon buried between two adjacent sampling times (t, t-1). The carbon content (mass percentage) in the new sediment sample obtained at sampling time t at sampling point i. The dry density of this new sediment sample. The sedimentary layer renewal amount is the difference between the sedimentary layer height at sampling point i at sampling time t and the sedimentary layer height at sampling time t-1. When the sedimentary layer height decreases, this value becomes negative, indicating that some of the carbon that has been fixed in the sedimentary layer is carried away by the disturbance of the sedimentary layer.

[0053] Dividing the carbon burial flux calculated by the above formula by the time interval between two sampling times (sampling period) yields the carbon burial rate in the time domain.

[0054] It should be noted that in the above calculation process, the amount of sedimentary layer renewal is the new sedimentary layer thickness. Therefore, the carbon burial rate calculated according to the above process refers to the carbon burial rate per unit area.

[0055] The calculation process for nitrogen burial rate is the same as above.

[0056] After obtaining the carbon burial rate of all sampling points, the carbon and nitrogen burial rate of the entire reservoir area can be calculated based on the distribution of sampling points.

[0057] Although the sediment sampling at each sampling point needs to be carried out sequentially, which may result in the sampling time of the sediment samples at each sampling point not being exactly the same, the asynchrony of sediment samples caused by different sampling times has little impact on the accuracy of the final assessment results, considering that the carbon and nitrogen cycle process of the ecosystem is relatively slow compared to the sampling time.

[0058] Specifically, in step S4, the overall carbon burial rate of the entire reservoir is calculated through the following steps:

[0059] S41. Construct a sedimentary layer grid model for the entire reservoir area based on the sampling points. Each grid cell in this sedimentary layer grid model is a polygon with three or four sampling points as vertices, such as... Figure 2 As shown, this is a sedimentary layer mesh model established using the Delaunay triangulation method, where each mesh cell contains three sampling points as vertices;

[0060] S42. For each grid cell, calculate the average carbon burial rate of that grid cell based on the carbon burial rate of the sampling points it contains.

[0061] S43. By summing the average carbon burial rates of all grid cells in the sedimentary layer grid model, the overall carbon burial rate of the entire reservoir area can be obtained.

[0062] By using an automated grid generation method, for reservoirs with indistinct or frequently changing hydrological or topographical features, the measured data of each sampling point can be fully utilized, effectively reducing the impact of potential local errors at a single sampling point on the overall calculation results. This makes the carbon burial rate of the grid cells more representative, and the method is also applicable to reservoirs that are still in the pre-planning stage.

[0063] Furthermore, in some embodiments, the sampling points are determined based on the different hydrological characteristics of the reservoir area. Therefore, each sampling point can represent the sedimentary characteristics of its area. Based on the sampling points set in this way, the overall carbon burial rate of the entire reservoir area can be calculated in the following way:

[0064] S41. For each sampling point, the corresponding representative area is determined using the area allocation method. The area of ​​the representative area is multiplied by the carbon burial rate of the sampling point to obtain the average carbon burial rate of the area where the sampling point is located.

[0065] The area of ​​the reservoir represented by each sampling point can be determined based on the distribution of the sampling points using area allocation methods such as the Thiessen polygon method or the grid method. For example, if the Thiessen polygon method is used, the reservoir area is divided into several polygons with each sampling point as a discrete point, and the area of ​​each polygon is the area of ​​the reservoir area represented by the corresponding sampling point. For some reservoir areas with relatively stable terrain, manual planning can also be used to determine the representative area corresponding to each sampling point.

[0066] S42. Sum the average carbon burial rates of all representative areas to obtain the overall carbon burial rate of the entire reservoir area.

[0067] Using representative areas constructed from each sampling point to calculate the carbon burial rate of the entire reservoir area can better match the hydrological characteristics of the reservoir and effectively reduce calculation errors. For some reservoirs with well-defined hydrological or topographical characteristics, the carbon burial rate calculated by this method is more accurate.

[0068] Similarly, the overall nitrogen burial rate of the entire reservoir area is calculated in the same way.

[0069] In summary, the carbon and nitrogen burial rates of reservoirs can be estimated using the methods described above, providing scientific data support for carbon and nitrogen cycle research, ecological environment assessment, and reservoir management strategy formulation in sediment-laden river reservoirs. For example, based on the acquired carbon and nitrogen burial rate data, the reservoir's contribution to carbon sequestration can be further analyzed, and the migration and transformation patterns of nitrogen in the reservoir ecosystem and its potential impact on water quality can be assessed. Simultaneously, this method and system also provide a feasible technical path for long-term monitoring of the dynamic changes in reservoir carbon and nitrogen burial, helping to promptly grasp the evolution trend of the reservoir's ecological environment and providing a strong basis for sustainable reservoir utilization and ecological protection decisions. Furthermore, by combining the reservoir's theoretical storage capacity, designed sedimentary layer height, and river runoff sediment content, the reservoir's carbon and nitrogen burial capacity can be estimated.

[0070] This invention also provides a system for monitoring and assessing the carbon and nitrogen burial rate in reservoirs of sandy rivers, used to monitor and assess the carbon and nitrogen burial rate in reservoirs. (Reference) Figure 4 Specifically, it includes:

[0071] The sedimentary layer measurement unit is used to measure the height of the sedimentary layer and calculate the amount of sedimentary layer renewal based on the change in sedimentary layer height.

[0072] The sedimentary layer sampling unit is used to acquire sedimentary layer samples from sampling points and to extract new sediment samples based on the amount of sedimentary layer renewal.

[0073] The elemental content determination unit is used to measure the content of greenhouse gas elements in new sediment samples;

[0074] The burial rate calculation unit is used to calculate the greenhouse gas burial rate of each sampling point based on the greenhouse gas element content, sediment layer renewal rate and sampling cycle, and to calculate the overall greenhouse gas element burial rate of the reservoir based on the greenhouse gas burial rates of all sampling points.

[0075] Specifically, the sediment measurement unit can use a combination of acoustic Doppler current profiler (ADCP) and underwater robot (AUV) to accurately measure the vertical distance from the water surface to the sediment surface at different sampling points by emitting acoustic signals to the bottom of the reservoir and receiving reflected waves, and combine this with the water level to obtain the sediment height.

[0076] Specifically, the sedimentary layer sampling unit can employ a columnar sampler or a box-type sampler. A robotic arm or winch system precisely lowers the sampling device to the designated sampling point. Once the sampling device reaches the sedimentary layer surface, a hydraulic or mechanical transmission mechanism drives the sampling tube (or sampling box) vertically into the sedimentary layer. The insertion depth is precisely controlled based on the sedimentary layer turnover rate to ensure complete capture of newly formed sediment samples within the corresponding time period. After sampling, a reverse-drive mechanism lifts the sampling tube (or sampling box) out of the water, and the sample is sealed for preservation to prevent loss or contamination during transportation and subsequent processing. For example, if the sedimentary layer turnover rate in a sampling cycle is calculated to be 5 cm, the insertion depth of the columnar sampler will be set to 10 cm. After extracting the sedimentary layer sample, the sediment within the top 5 cm is selected as the new sediment sample, ensuring that the obtained sample covers the newly deposited material within that cycle, providing an accurate material basis for subsequent elemental content determination.

[0077] Specifically, the method for determining the location of sampling points can refer to the methods provided in the above-mentioned detection and evaluation methods.

[0078] Specifically, the elemental content determination unit can employ high-precision elemental analyzers, such as elemental analyzers, inductively coupled plasma mass spectrometers (ICP-MS), or atomic absorption spectrophotometers (AAS). Before determining the elemental content, the collected sediment samples need to undergo a series of pretreatments, including freeze-drying to remove moisture, grinding and sieving to ensure sample homogeneity, and using appropriate digestion methods (such as microwave digestion or wet digestion) to convert the solid sediments into solvent-soluble liquid samples. For example, for the determination of total carbon and total nitrogen content, an elemental analyzer can be used to fully combust the treated dried powder sample in a high-temperature combustion tube, converting carbon and nitrogen elements into carbon dioxide and nitrogen oxides, respectively. The content is then measured using infrared detectors and thermal conductivity detectors. Through these advanced analytical methods, the content of target elements such as carbon and nitrogen in sediment samples can be accurately determined, providing crucial basic data for subsequent calculations of carbon and nitrogen burial rates.

[0079] Specifically, the burial rate calculation unit can be a computing device that runs various software, such as a central processing unit (CPU), microprocessor, digital signal processor (DSP), microcontroller unit (MCU), or artificial intelligence processor.

[0080] Specifically, the calculation of the greenhouse gas burial rate at each sampling point and the greenhouse gas burial rate of the entire reservoir area can refer to the methods provided in the above detection and evaluation methods.

[0081] In conclusion, the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for monitoring and evaluating the carbon and nitrogen burial rate in reservoirs of sandy rivers, characterized in that, Includes the following steps: Obtain the sediment layer update amount, which is the difference between the sediment layer height at the current sampling time and the sediment layer height at the previous sampling time; Sedimentary samples were obtained from multiple sampling points within the reservoir area. New sediment samples were extracted based on the amount of sedimentary renewal, and the content of greenhouse gas elements in each new sediment sample was determined. The greenhouse gas burial rate of each sampling point is calculated based on the sampling period, the amount of sediment renewal at each sampling point, and the content of greenhouse gas elements. The overall greenhouse gas burial rate of the reservoir is estimated based on the greenhouse gas burial rates of all sampling points obtained at multiple sampling times.

2. The method according to claim 1, characterized in that, The amount of sediment layer renewal is obtained through the following steps: Multiple sonar scanning paths are preset according to the characteristics of inflow into the reservoir, and acoustic detection methods are used to obtain the surface data of the sedimentary layer at the current sampling time. The surface data of the sedimentary layer includes the height of the sedimentary layer. The sedimentary layer surface data is projected onto a preset grid, and the sedimentary layer update amount at each preset grid node is calculated based on the sedimentary layer surface data obtained in this sampling and the sedimentary layer surface data obtained in the previous sampling time.

3. The method according to claim 2, characterized in that, The location of the sampling point is determined by the following steps: Based on the obtained sedimentary layer update, a sedimentation rate distribution model is established, and the sedimentation rate at each grid node is calculated. When the sedimentation rate is greater than the sedimentation rate threshold, this preset grid node is used as the sampling point of the sedimentary layer.

4. The method according to claim 1, characterized in that, The content of greenhouse gas elements is obtained through the following steps: Dry the new sediment samples; The dried new sediment sample was completely burned, causing all greenhouse gas elements to be oxidized into oxides; The content of local greenhouse gas elements in new sediment samples is determined by column chromatography. The content of greenhouse gas elements in the new sediment samples is obtained by the ratio of the mass of the new sediment samples that participated in combustion to the local greenhouse gas carbon content.

5. The method according to claim 1, characterized in that, The burial rate of greenhouse gas elements is calculated using the following steps: The greenhouse gas element content in the new sediment sample at the sampling point is calculated by multiplying the dry density of the new sediment sample by the sediment layer renewal rate, and then dividing the resulting product by the sampling period between adjacent sampling times. This product represents the greenhouse gas element burial rate.

6. The method according to claim 1, characterized in that, The following steps are used to estimate the overall rate of greenhouse gas element burial: A sedimentary layer grid model of the entire reservoir area is constructed based on the sampling points. Each grid cell in this sedimentary layer grid model is a polygon with three or four sampling points as vertices. For each grid cell, the average greenhouse gas burial rate of that grid cell is calculated based on the greenhouse gas burial rates of the sampling points it contains. The total greenhouse gas burial rate of the entire reservoir area can be obtained by summing the average greenhouse gas burial rates of all grid cells in the sedimentary layer grid model.

7. The method according to claim 1, characterized in that, The following steps are used to estimate the overall rate of greenhouse gas element burial: For each sampling point, the corresponding representative area is determined using the area allocation method. The area of ​​the representative area is multiplied by the carbon burial rate of the sampling point to obtain the average carbon burial rate of the area where the sampling point is located. The average carbon burial rates of all representative areas are summed to obtain the overall carbon burial rate of the entire reservoir area.

8. A monitoring and assessment system for carbon and nitrogen burial rates in reservoirs of sandy rivers, characterized in that, include: The sedimentary layer measurement unit is used to measure the height of the sedimentary layer and calculate the amount of sedimentary layer renewal based on the change in sedimentary layer height. The sedimentary layer sampling unit is used to acquire sedimentary layer samples from sampling points and to extract new sediment samples based on the amount of sedimentary layer renewal. The elemental content determination unit is used to measure the content of greenhouse gas elements in new sediment samples; The burial rate calculation unit is used to calculate the greenhouse gas burial rate of each sampling point based on the greenhouse gas element content, sediment layer renewal rate and sampling cycle, and to calculate the overall greenhouse gas element burial rate of the reservoir based on the greenhouse gas burial rates of all sampling points.

9. The system according to claim 8, characterized in that, The burial rate calculation unit estimates the overall burial rate of greenhouse gas elements through the following steps: A sedimentary layer grid model of the entire reservoir area is constructed based on the sampling points. Each grid cell in this sedimentary layer grid model is a polygon with three or four sampling points as vertices. For each grid cell, the average greenhouse gas burial rate of that grid cell is calculated based on the greenhouse gas burial rates of the sampling points it contains. The total greenhouse gas burial rate of the entire reservoir area can be obtained by summing the average greenhouse gas burial rates of all grid cells in the sedimentary layer grid model.

10. The system according to claim 8, characterized in that, The burial rate calculation unit estimates the overall burial rate of greenhouse gas elements through the following steps: For each sampling point, the corresponding representative area is determined using the area allocation method. The area of ​​the representative area is multiplied by the carbon burial rate of the sampling point to obtain the average carbon burial rate of the area where the sampling point is located. The average carbon burial rates of all representative areas are summed to obtain the overall carbon burial rate of the entire reservoir area.

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