A method for establishing target waters based on shell tracing of Hyriopsis cumingii 87 Sr / 86 Sr ratio baseline method

Abstract

The invention discloses a method for establishing a target water area based on backtracking of Hyriopsis cumingii shells. 87 Sr / 86 The method of Sr ratio baseline belongs to the field of ecological technology, including collecting samples of Hyriopsis cumingii, shell cleaning, shell slicing, shell grinding, shell in situ micro-area analysis, 87 Sr / 86 Sr analysis, shell growth ring measurement, establishment 87 Sr / 86 The present invention is based on the steps of the Sr ratio baseline. 87 Sr / 86 Sr ratio and water environment 87 Sr / 86 The direct relationship between the Sr ratio and the water environment 87 Sr / 86 The test samples of Sr ratio survey can provide 87 Sr / 86 Sr ratio fluctuation, establish 87 Sr / 86 The Sr ratio baseline provides an important basis for temporal stability assessment and can effectively invert the waters near the sampling point in recent years. 87 Sr / 86 Sr ratio has the advantages of fast analysis speed, convenience and low cost.

Description

Technical Field

[0001] The present invention relates to the field of ecological technology, in particular to a method for establishing a target water area based on the shell tracing of Hyriopsis cumingii 87 Sr / 86 Sr ratio baseline method. Background Art

[0002] In recent decades, with the rapid development of social economy, human activities such as water pollution, reclamation, channel improvement, sand mining and shoreline hardening have continued to intensify, leading to a sharp decline in aquatic biological resources, serious degradation of habitats, and a significant decrease in biodiversity. In order to achieve comprehensive protection of aquatic biological resources and restoration of habitat systems in the Yangtze River Basin, a permanent fishing ban will be implemented in key waters of the Yangtze River Basin for a temporary period of ten years from January 1, 2021, and aquatic biological resources will be gradually protected and restored. Aquatic biological protection and resource conservation is a complex and long-term process. While the effects of the fishing ban are constantly being consolidated, strengthening the protection and restoration of aquatic biological habitats should be a key focus. Laws and regulations such as the Yangtze River Protection Law of the People's Republic of China and the Wildlife Protection Law of the People's Republic of China have put forward clear requirements for habitat protection.

[0003] Understanding the habitat utilization of fish at different stages, including birth origin and migration history, from the perspective of individuals and populations is a prerequisite for identifying and protecting critical fish habitats. Methods for identifying the birth origin and migration history of fish mainly include early resource surveys, in vitro electronic telemetry or physical tags, etc. These methods can be used to identify the habitat and life history changes of juvenile and larger fish, but lack the ability to trace back the life history of fish. Fish otoliths have the characteristics of continuous growth and are almost not reabsorbed after formation. In the process of formation, their otoliths are mainly composed of the following: 87 Sr / 86 Sr hardly fractionates and can be considered as a direct reflection of its source. 87 Sr / 86 Sr ratio, so the water environment experienced by fish in their life history 87 Sr / 86 The Sr ratio can be fully recorded by otoliths. 87 Sr / 86 Sr ratio and water environment in the target area 87 Sr / 86 The Sr ratio can be compared with the background to identify the habitat of fish during the formation of otoliths and to identify fish in the presence of 87 Sr / 86 Migration behavior between habitats with heterogeneous Sr ratios.

[0004] Detailed investigation of natural water bodies within the basin 87 Sr / 86 Sr ratio, construct target water area87 Sr / 86 The Sr ratio baseline is calculated using 87 Sr / 86 The Sr ratio is a prerequisite for reconstructing the history of fish habitat use and migration. 87 Sr / 86 The Sr ratio baseline requires data in both spatial and temporal dimensions and is determined through water sampling and analysis. 87 Sr / 86 The Sr ratio is usually real-time data at a single time in a geographical area, and can only reflect the 87 Sr / 86 Sr ratio, can not be used to study the past water environment. 87 Sr / 86 Research on fish habitat utilization based on Sr ratio started late in my country and lacks historical water environment data. 87 Sr / 86 The Sr ratio record seriously restricts the study of fish habitat utilization and migration history. Since the fishing ban in the Yangtze River, the fish resources in the Yangtze River have gradually recovered, but the changes in their habitat utilization are still unclear, and there is a lack of effective support for targeted habitat protection. Therefore, it is urgent to establish a water environment monitoring system since the fishing ban. 87 Sr / 86 A baseline of Sr ratios should be established, and if conditions permit, a baseline for medium to long time scales before the fishing ban should be established to support long-term research on the history of fish habitat use and migration. Summary of the Invention

[0005] Technical problems to be solved: 87 Sr / 86 The present invention provides a method for establishing a target water area based on the backtracking of Hyriopsis cumingii shells. 87 Sr / 86 The Sr ratio baseline method has the advantages of being fast, accurate, and capable of retrospective research, overcoming the high labor costs and analysis costs of long-term water environment sampling and the inability to trace back past periods of time without sampling. 87 Sr / 86 The disadvantage of the change in Sr ratio is the backtracking waters 87 Sr / 86 Sr ratio changes, establishing target waters 87 Sr / 86 The Sr ratio baseline provides a reliable means.

[0006] Technical solution: The present invention is a method for establishing target waters based on the shell tracing of Hyriopsis cumingii. 87 Sr / 86 A method for determining an Sr ratio baseline, the method comprising the following steps:

[0007] Step 1: Collect samples of Hyriopsis cumingii: Collect live samples of Hyriopsis cumingii in representative target waters for shell in situ analysis. 87 Sr / 86 Sr ratio analysis;

[0008] Step 2: Shell cleaning: The collected Hyriopsis cumingii was split open to remove soft tissue and clean the external attachments of the shell. Then, the shell was repeatedly cleaned with deionized water for 3 to 6 times on the outside and inside.

[0009] Step 3: Shell sectioning: Use a cutting machine to cut along the maximum growth axis of the shell from the top to the ventral edge, cut a 3mm segment including the shell top, and embed it in epoxy resin;

[0010] Step 4: Shell grinding: Use sandpaper to grind the shell sample from both sides, stop grinding when approaching the top of the shell, then polish it, rinse it with deionized water, and dry it;

[0011] Step 5: Shell in situ micro-area 87 Sr / 86 Sr analysis: Laser ablation coupled with multi-collector inductively coupled plasma mass spectrometry (LA-MC-ICP-MS) was used to perform line scanning from the outer to the inner calcified layer of the shell to obtain the calcified layer of the shell. 87 Sr / 86 Sr ratio;

[0012] Step 6: Shell growth ring measurement: Use a metallographic microscope to reflect light to take an image of the shell sample, use the microscope's built-in measurement software to measure the incremental width along the laser scanning line, and then 87 Sr / 86 Sr ratio data were incorporated into the temporal context;

[0013] Step 7: Build 87 Sr / 86 Sr ratio baseline: Generalized additive model (GAM) was used to analyze the Sr ratio of shell samples from the outside to the inside. 87 Sr / 86 The Sr ratio changes according to the shell sample 87 Sr / 86 The Sr ratio and its growth period can be used to infer the growth of the same target water area in different time periods. 87 Sr / 86 Sr ratio; then repeat the above steps 1 to 7 based on the shells of Hyriopsis cumingii collected from different locations in the target waters to establish the target water environment in a continuous time period. 87 Sr / 86 Sr ratio baseline.

[0014] Preferably, the specific steps of shell grinding in step 4 are: first fix the resin block containing the shell slice on the glass sheet with hot melt glue, use 500grit waterproof and wear-resistant sandpaper to grind one side of the shell, apply uniform force during grinding to prevent the slice from being worn off-center, and observe the whole process under a metallographic microscope. After grinding one side of the shell close to the top of the shell, use 2000grit and 4000grit sandpaper to fine-grind its surface; then use a heating plate to melt the hot melt glue and turn the resin sheet over, repeat the above grinding process to grind the other side of the shell until the top of the shell is exposed, and then use a polishing cloth soaked in silica suspension to polish the shell surface.

[0015] Preferably, in step 5, the laser energy density in the laser ablation coupled multi-collector inductively coupled plasma mass spectrometry detection is 6 J / cm 2 The spot beam diameter of the ablation is 100 μm, the frequency is 10 Hz, the ablation speed is 10 μm / s, the He flow rate is 350 mL / min, and the N2 flow rate is 5 mL / min.

[0016] Preferably, the analysis of the shell by laser ablation coupled to a multi-collector inductively coupled plasma mass spectrometer in step 5 includes a 20 s background measurement and ablation time required for a cross section from the outside to the inside; during the analysis, apatite standards and otoliths of the marine fish four-fingered threadfin oyster are used as reference standards, and the standards are tested every 20 minutes before and during the test to determine the true 87 Sr / 86 Sr ratio.

[0017] Preferably, in step 7, the measured values ​​of the shells of Hyriopsis cumingii in different target waters are 87 Sr / 86 The Sr ratio is combined with the growth structure of the shell to infer the upper target water area in different time periods. 87 Sr / 86 Sr ratio.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] 1. The present invention is based on shells 87 Sr / 86 Sr ratio and water environment 87 Sr / 86 The direct relationship between the Sr ratio and the water environment 87 Sr / 86 The Sr ratio of the test samples was investigated by in-situ laser ablation analysis, which has a fast analysis speed compared with the pre-treated water samples. 87 Sr / 86 Sr ratio analysis is more convenient, faster and less costly;

[0020] 2. This method uses the shells of Hyriopsis cumingii as test samples, which have the advantages of wide distribution and easy access. The calcified layer of the shell of Hyriopsis cumingii has a clearly visible alternating light and dark band formed by periodic growth, with obvious growth lines and increments, so that the calcified layer of the shell can be 87 Sr / 86 The Sr ratio is placed in a precise time context to infer the environment at different time periods 87 Sr / 86 Sr ratio; Hyriopsis cumingii shells can be used as environmental 87 Sr / 86 A surrogate for the spatiotemporal record of Sr ratios, used to retrospectively establish target waters 87 Sr / 86 The Sr ratio baseline provides a reference background for reconstructing the life history of fish in the region using otoliths and tracing their origins and migrations;

[0021] 3. The shell of Hyriopsis cumingii can provide 87 Sr / 86 The fluctuation of Sr ratio is a reliable alternative in the absence of water sample analysis in previous years. 87 Sr / 86 The Sr ratio baseline provides an important basis for temporal stability assessment, and has the advantages of good result stability and strong discriminability, which can effectively invert the waters near the sampling point in recent years. 87 Sr / 86 Sr ratio. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a flow chart of the method of the present invention;

[0023] Figure 2 This is a physical diagram of the slice angle of the cuming clam shell of the present invention;

[0024] Figure 3 This is the diameter of the shell of the cuming oyster from the top to the inner edge caught in the Anqing section of the Yangtze River. 87 Sr / 86 Sr ratio line graph, the horizontal axis represents the distance from the shell top to the inner edge, the vertical axis represents 87 Sr / 86 Sr ratio, the blue solid line represents the GAM fitting 87 Sr / 86 Sr ratio, the gray range on both sides of the blue solid line represents 87 Sr / 86 Confidence intervals of the GAM fitted values ​​of the Sr ratio (95% confidence level). The gray and black column backgrounds represent the different growth stages of the shells (the gray column area corresponds to rapid growth in spring and summer, and the black column area corresponds to slow growth in autumn and winter);

[0025] Figure 4 The shell of the cuming oyster, captured in the Jiujiang section of the Yangtze River, is from the top to the inner edge. 87 Sr / 86 Sr ratio line graph, the horizontal axis represents the distance from the shell top to the inner edge, the vertical axis represents 87 Sr / 86 Sr ratio, the blue solid line represents the GAM fitting 87 Sr / 86 Sr ratio, the gray range on both sides of the blue solid line represents 87 Sr / 86 Confidence intervals of the GAM fitted values ​​of the Sr ratio (95% confidence level). The gray and black column backgrounds represent the different growth stages of the shells (the gray column area corresponds to rapid growth in spring and summer, and the black column area corresponds to slow growth in autumn and winter);

[0026] Figure 5 The shell of a Hyriopsis cumingii caught in Nanjing section of Yangtze River, from the top to the inner edge. 87 Sr / 86 Sr ratio line graph, the horizontal axis represents the distance from the shell top to the inner edge, the vertical axis represents 87 Sr / 86 Sr ratio, the blue solid line represents the GAM fitting 87 Sr / 86 Sr ratio, the gray range on both sides of the blue solid line represents 87 Sr / 86 Confidence intervals of the GAM fitted values ​​of the Sr ratio (95% confidence level). The gray and black column backgrounds represent the different growth stages of the shells (the gray column area corresponds to rapid growth in spring and summer, and the black column area corresponds to slow growth in autumn and winter);

[0027] Figure 6 This is the diameter from the top to the inner edge of the shell of Hyriopsis cumingii caught in the Duchang Lake area of ​​Poyang Lake. 87 Sr / 86 Sr ratio line graph, the horizontal axis represents the distance from the shell top to the inner edge, the vertical axis represents 87 Sr / 86 Sr ratio, the blue solid line represents the GAM fitting 87 Sr / 86 Sr ratio, the gray range on both sides of the blue solid line represents 87 Sr / 86 Confidence interval of the GAM fitted value of the Sr ratio (95% confidence level). The gray and black column backgrounds represent the different growth stages of the shells (the gray column area corresponds to rapid growth in spring and summer, and the black column area corresponds to slow growth in autumn and winter). DETAILED DESCRIPTION

[0028] To make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the following Figures 1 to 6 The technical solutions of the embodiments of the present invention are clearly and completely described. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the described embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field are within the scope of protection of the present invention.

[0029] Example 1: The cumingii oyster used in the present invention belongs to bivalves. The shells of bivalves generally have two layers, namely the outer shell (a thin organic outer layer) and the calcified layer. 95-99.9% of the calcified layer is calcium carbonate. 87 Sr / 86 The Sr ratio also reflects the surrounding environment 87 Sr / 86 Sr ratio, and continued growth, and bivalves do not move much during their lifetime, so bivalves can be used as biological monitoring "sentinels" to reconstruct their location at different times using shells (calcified layers). 87 Sr / 86 Sr ratio, which can be used to backtrack and establish target water areas 87 Sr / 86 The present invention uses the shell of Hyriopsis cumingii as the test sample, which has the advantages of wide distribution and easy access. The calcified layer of the shell of Hyriopsis cumingii has a clear and visible alternating light and dark band formed by periodic growth, with obvious growth lines and increments, so that the calcified layer of the shell can be 87 Sr / 86 The Sr ratio is placed in a precise time context to infer the environment at different time periods 87 Sr / 86 Sr ratio; Hyriopsis cumingii shells can be used as environmental 87 Sr / 86 A surrogate for the spatiotemporal record of Sr ratios, used to retrospectively establish target waters 87 Sr / 86 The Sr ratio baseline provides a reference background for using otoliths to reconstruct the life history of fish in the region and trace their origin and migration.

[0030] like Figure 1 As shown, the present invention is a method for establishing a target water area based on the shell backtracking of the cuming oyster 87 Sr / 86 A method for determining an Sr ratio baseline, the method comprising the following steps:

[0031] Step 1: Collect samples of Hyriopsis cumingii: Collect live samples of Hyriopsis cumingii in representative target waters for shell in situ analysis. 87 Sr / 86 Sr ratio analysis; specific sampling points include the Anqing section of the Yangtze River, the Jiujiang section of the Yangtze River, the Nanjing section of the Yangtze River, and the Duchang Lake area of ​​Poyang Lake.

[0032] Step 2: Shell cleaning: Cut open the collected Hyriopsis cumingii to remove the soft tissue, and use a brush to clean the external attachments of the shell. Then use deionized water to repeatedly clean the outside and inside of the shell 3 to 6 times, and put it in an oven to dry at 37°C.

[0033] Step 3: Shell slicing: Use a cutting machine to cut along the maximum growth axis of the shell from the top to the ventral edge (such as Figure 2 A 3 mm segment containing the shell top was cut and placed into a silicone mold and embedded in epoxy resin.

[0034] Step 4: Shell grinding: Use sandpaper to grind the shell sample from both sides. Use a metallographic microscope to observe the position of the shell top during the grinding process. Stop grinding when approaching the shell top, then polish, wash the shell slices with deionized water, and put them in an oven to dry at 37°C. The specific steps of shell grinding: first fix the resin block containing the shell slices on the glass slide with hot melt glue, use 500grit waterproof and wear-resistant sandpaper to grind one side of the shell, and apply uniform force during grinding to prevent the slice from being ground sideways. Observe the whole process under a metallographic microscope. After grinding one side of the shell close to the shell top, use 2000grit and 4000grit sandpaper to finely grind it to make its surface smooth; then use a hot plate to melt the hot melt glue and turn the resin sheet over, repeat the above grinding process to grind the other side of the shell until the shell top is exposed, and then use a polishing cloth soaked in silica suspension to polish the shell surface.

[0035] Step 5: Shell in situ micro-area 87 Sr / 86 Sr analysis: Laser ablation coupled to a multi-collector inductively coupled plasma mass spectrometer (LA-MC-ICP-MS) was performed using a RESOlution SE 193 nm laser ablation system coupled with a Neptune plus multi-collector inductively coupled plasma mass spectrometer. The laser energy density was 6 J / cm 2The spot diameter of the ablation is 100μm, the frequency is 10Hz, and the ablation speed is 10μm / s. Line scanning is used to laser ablate the shell micro-area sampling from the outer side to the inner calcified layer along the top of the shell. The ablated material is taken out of the sample cell with high-purity He as the carrier gas, mixed with high-purity Ar and N2, and then enters the mass spectrometer to analyze the strontium isotope of the shell. The He flow rate is 350 mL / min and the N2 flow rate is 5 mL / min. Before the Sr isotope laser ablation of the shell, a 20s blank background measurement is received, and the sampling time for each time is 0.524s; the total integration time is adjusted according to the line scan length, that is, the ablation time required for the cross section from the outer side to the inner side. During the analysis, apatite standards (Durango) and otoliths of the marine fish four-fingered threadfin prawn (Eleutheronema tetradactylum) are used as 87 Sr / 86 Sr ratio reference standard (Four-fingered threadfin otolith 87 Sr / 86 The Sr ratio is the same as the global ocean ratio). The standard sample is tested every 20 minutes before and during the test to determine the true 87 Sr / 86 Sr ratio to determine the precision and accuracy of instrument operation and control the detection quality of data.

[0036] Durango was analyzed as a standard to monitor isotopic (Kr and Rb), doubly charged (REE), and polyatomic Ca-Ar and Ca-PO interferences to determine if corrections were necessary. Isotopic data were acquired in low-resolution static mode. The mass numbers measured by MC-ICP-MS during the analysis and the corresponding isotopes are shown in Table 1. Data processing and correction were performed using the open-source LA-MC-ICP-MS data rapid offline reduction program "SrDR."

[0037] .

[0038] Step 6: Shell growth ring measurement: Use a metallographic microscope to reflect light to take an image of the shell sample, use the microscope's built-in measurement software to measure the incremental width along the laser scanning line, and then 87 Sr / 86 Sr ratio data were put into a temporal context.

[0039] Step 7: Build 87 Sr / 86 Sr ratio baseline: Generalized additive model (GAM) was used to analyze the Sr ratio of shell samples from the outside to the inside. 87 Sr / 86 The Sr ratio changes according to the shell sample 87 Sr / 86The Sr ratio and its growth period can be used to infer the growth of the same target water area in different time periods. 87 Sr / 86 Sr ratio; then according to the shells of Hyriopsis cumingii collected from different locations in the target waters, according to the measured Sr ratio of the shells of Hyriopsis cumingii in different target waters 87 Sr / 86 The Sr ratio is combined with the growth structure of the shell to infer the upper target water area in different time periods. 87 Sr / 86 Sr ratio, the target water environment in a continuous time period can be established 87 Sr / 86 Sr ratio baseline. Establish shell 87 Sr / 86 Specific steps for the relationship between Sr ratio and time: The Sr ratio was obtained by LA-MC-ICP-MS along the cross section of the shell. 87 Sr / 86 The raw Sr data were subjected to GAM analysis using the MGCV package in the statistical programming software R. Since the number of laser sampling points obtained for each shell was different, a thin plate regression spline smoothing function was fitted for each individual. The maximum effective degree of freedom (edf) allowed for fitting (i.e., the basis size k) was given by k = 10N 2 / 9 Definition, where N is the number of laser sampling points per shell slice. The final value recorded from the shell top along the growth axis of the outer to the inner calcification layer is 87 Sr / 86 The Sr ratio obtained the GAM fitting value and its confidence interval (95% confidence level), and the shell 87 Sr / 86 The Sr ratio can be used to infer the water environment in the corresponding time period. 87 Sr / 86 Sr ratio.

[0040] In this example, live Hyriopsis cumingii was captured in the middle and lower reaches of the Yangtze River and Poyang Lake. The evaluation results are as follows: Figures 3 to 6 As shown in the figure, the horizontal axis represents the growth length from the top of the shell along the outer calcified layer to the inner calcified layer, and the vertical axis represents the shell in the life history. 87 Sr / 86 Sr ratio data. Figures 3-5 Shown are shells of Hyriopsis cumingii caught in the Anqing, Jiujiang, and Nanjing sections of the Yangtze River mainstream. 87 Sr / 86 The Sr ratio has a small change range, which is basically in the range of 0.7106~0.7110. This result is close to the measured value of the water samples in the Yangtze River mainstream, indicating that the water in the Yangtze River mainstream is relatively stable during the growth period of these Hyriopsis cumingii individuals. 87 Sr / 86The stability of Sr ratio. Figure 6 Shown are shells of Hyriopsis cumingii caught in the Duchang Lake area of ​​Poyang Lake. 87 Sr / 86 The Sr ratio data has a certain fluctuation but the fluctuation range is very small, ranging from 0.7140 to 0.7150. This result is consistent with the measured value of the water samples in the corresponding lake area, indicating that the water in this area is relatively stable during the growth period of Hyriopsis cumingii. 87 Sr / 86 Stability of the Sr ratio.

[0041] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for establishing target waters based on the shell tracing of Hyriopsis cumingii 87 Sr / 86 The Sr ratio baseline method is characterized in that The method comprises the following steps: Step 1: Collect samples of Hyriopsis cumingii: Collect live samples of Hyriopsis cumingii in representative target waters for shell in situ analysis. 87 Sr / 86 Sr ratio analysis; Step 2: Shell cleaning: The collected Hyriopsis cumingii was split open to remove soft tissue and clean the external attachments of the shell. Then, the shell was repeatedly cleaned with deionized water for 3 to 6 times on the outside and inside. Step 3: Shell sectioning: Use a cutting machine to cut along the maximum growth axis of the shell from the top to the ventral edge, cut a 3mm segment including the shell top, and embed it in epoxy resin; Step 4: Shell grinding: Use sandpaper to grind the shell sample from both sides, stop grinding when approaching the top of the shell, then polish it, rinse it with deionized water, and dry it; Step 5: Shell in situ micro-area 87 Sr / 86 Sr analysis: Laser ablation coupled with multi-collector inductively coupled plasma mass spectrometry (LA-MC-ICP-MS) was used to perform line scanning from the outer to the inner calcified layer of the shell to obtain the calcified layer of the shell. 87 Sr / 86 Sr ratio; Among them, in the laser ablation connection multi-collector inductively coupled plasma mass spectrometry detection, the laser energy density is 6J / cm 2 The spot diameter of the ablation was 100 μm, the frequency was 10 Hz, the ablation speed was 10 μm / s, the He flow rate was 350 mL / min, and the N2 flow rate was 5 mL / min. The analysis of the shells by laser ablation connected to a multi-collector inductively coupled plasma mass spectrometer included a 20-second background measurement and the ablation time required for the cross section from the outside to the inside. During the analysis, apatite standards and otoliths of the marine fish four-fingered threadfin were used as reference standards. The standards were tested every 20 minutes before and during the test to determine the true 87 Sr / 86 Sr ratio; Step 6: Shell growth ring measurement: Use a metallographic microscope to reflect light to take an image of the shell sample, use the microscope's built-in measurement software to measure the incremental width along the laser scanning line, and then 87 Sr / 86 Sr ratio data were incorporated into the temporal context; Step 7: Build 87 Sr / 86 Sr ratio baseline: Generalized additive model (GAM) was used to analyze the Sr ratio of shell samples from the outside to the inside. 87 Sr / 86 The Sr ratio changes according to the shell sample 87 Sr / 86 The Sr ratio and its growth period can be used to infer the growth of the same target water area in different time periods. 87 Sr / 86 Sr ratio; then repeat the above steps 1 to 7 based on the shells of Hyriopsis cumingii collected from different locations in the target waters to establish the target water environment in a continuous time period. 87 Sr / 86 Sr ratio baseline.

2. The method for establishing target waters based on the shell tracing of Hyriopsis cumingii according to claim 1 87 Sr / 86 The Sr ratio baseline method is characterized in that The specific steps for shell grinding in step 4 are as follows: first, fix the resin block containing the shell slice on the glass slide with hot melt glue, use 500grit waterproof and wear-resistant sandpaper to grind one side of the shell, and apply uniform force during grinding to prevent the slice from being worn off-center. Observe the entire process under a metallographic microscope. After grinding one side of the shell close to the top of the shell, use 2000grit and 4000grit sandpaper to fine-grind its surface; then use a heating plate to melt the hot melt glue and turn the resin sheet over, repeat the above grinding process to grind the other side of the shell until the top of the shell is exposed, and then use a polishing cloth soaked in silica suspension to polish the shell surface.

3. Establishing target waters based on tracing back the shells of Hyriopsis cumingii according to any one of claims 1 to 2. 87 Sr / 86 The Sr ratio baseline method is characterized in that In step 7, the measured values ​​of the shells of Hyriopsis cumingii in different target waters are 87 Sr / 86 The Sr ratio is combined with the growth structure of the shell to infer the upper target water area in different time periods. 87 Sr / 86 Sr ratio.

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