A method for correcting stalagmite deposits on a near-century scale using plutonium isotopes 210 Pb ex Dating method

Abstract

The application provides a method for correcting stalagmite deposition of nearly a century scale by using plutonium isotope 210 Pb ex The method comprises the following steps: obtaining Pu and 239,240 Pb 210 Data of different layers of the stalagmite deposition, finding the depth corresponding to the layer position of the maximum peak of Pu in 1963, ex Pb 239,240 The data of the maximum peak of Pu in 1963, 210 Pb ex The specific activity value in the layer position, the theoretical 210 Pb ex Specific activity value corresponding to 1963 and 239,240 The depth of the layer position of the maximum peak of Pu, the measured 210 Pb ex Specific activity of the sample, and the curve fitting process of the data points of the deposition depth, so that the fitting curve is forced to pass through the measured point of the surface deposition of the stalagmite, the theoretical point corresponding to 1963, a new exponential decay function nonlinear fitting curve dating equation is obtained to correct the stalagmite deposition 210 Pb ex The fitting curve dating equation of the dating method, and the corrected deposition rate and the corresponding deposition age of each layer are obtained.

Description

Technical Field

[0001] This invention relates to the field of sediment dating technology, and more specifically, to a method for correcting travertine deposits on a near-century timescale using plutonium isotopes. 210 Pb ex Dating method. Background Technology

[0002] Travertine deposits are typical calcium carbonate sediments in karst regions, possessing significant commercial tourism value (e.g., in 5A-level scenic areas like Huanglong and Jiuzhaigou) and serving as crucial indicators for reconstructing climate and environmental changes. Since the Industrial Revolution, regional and global calcium carbonate deposition, climate, and environment have undergone significant alterations. Accurately determining the formation age of travertine deposits on a near-century timescale is a key parameter for studying their depositional rates and reconstructing local climate and environmental changes.

[0003] Currently, carbonate sediments (stalagmites, travertine, coral reefs, etc.) with a scale of nearly 100 years are mostly utilized... 210 Pb ex To determine the year. 210 Pb ex The main principle of dating is: 210 Pb (lead-210) passes through the atmosphere 222 Radon-222 decays and is deposited into water bodies through atmospheric deposition. Due to... 210 Pb is particulate reactive and can quickly transfer into sediments, thus appearing in the sediments. 210 Pb excess (excess lead-210: 210 Pb ex ), 210 Pb ex The vertical distribution within sedimentary layers follows the decay law, thus it can be used for sediment dating. However, 210 Pb ex Dating methods require the following basic assumptions: ① The sediments possess the characteristics of a closed system; ② 210 Pb has a short retention time in water; ③ after sedimentation 210 Pb does not undergo post-deposition migration; ④ Sediment samples 210 Pb sup (Supported lead-210) should be related to its parent body 226 Ra (radium-226) remains in equilibrium. Commonly used calculation models are mostly based on constant... 210 Pb ex Initial activity (CIC model), constant sedimentation rate and deposition flux (CFCS model) or constant 210 Pb ex The CRS model makes three assumptions regarding settling flux. These are typically explained... 210 Pb exWhen analyzing data, one of the models is used for dating based on the specific sedimentary environment. However, due to the numerous biological and abiotic factors that often influence actual sedimentary environments, such as physical or biological disturbances in shallow water, sediment compaction effects, and grain size effects, the above assumptions are difficult to fully satisfy. Karst-origin travertine, especially those with a loose structure, is not in a completely closed system due to long-term immersion in karst water and material exchange, and may have undergone later dating. 210 The addition and migration of Pb, thus making 210 Pb ex Dating methods yield significant errors in complex hydrodynamic and sedimentary environments such as karst regions. Therefore, a single dating method... 210 Pb ex Dating methods are difficult to obtain highly accurate ages of travertine deposits due to factors such as sedimentary disturbances.

[0004] In addition, a few researchers also used 239, 240 The peak characteristic timescale of Pu specific activity is used to date soils, coral reefs, marine sediments, etc., on a timescale of nearly 100 years. 239, 240 Pu, a typical man-made radionuclide, primarily originates from human nuclear activities such as atmospheric nuclear weapons testing, nuclear accident leaks, and emissions from nuclear facilities. In July 1945, the United States detonated an atomic bomb called "Trinity," marking the beginning of the nuclear age. However, the nuclear tests released by these nuclear tests into the global environment... 239, 240 The earliest detection of Pu dates back to 1952±2, and this has been used as a reference for global sediments. 239, 240 The Pu depositional record begins at this point. The subsequent US-Soviet arms race propelled atmospheric nuclear testing to its peak, with 177 atmospheric nuclear tests conducted globally in 1962 alone (approximately 35% of all atmospheric nuclear tests conducted between 1945 and 1996), releasing massive amounts of nuclear energy into the global atmosphere. 239, 240 Pu, these atmospheric elements 239, 240 Pu then gradually settled back to the ground. In the 1963 atmosphere... 239, 240 Pu sedimentation peaked and was recorded in the sediments, thus making 1963 a globally recognized sediment year. 239, 240 The Pu timescale. In addition, there are nuclear tests at Chernobyl and Lop Nur, which have regional impacts. 239, 240 The timescale within the area where Pu settlement has a significant impact. Therefore, 239, 240 Pu had 1952-1954 239, 240 The three main typical stratigraphic dating timescales are the initial detection time of Pu, the 1963 atmospheric nuclear test deposition peak (globally applicable), and the 1986 Chernobyl deposition peak (not globally applicable). These are relative to timescales influenced by factors such as grain size effect, compaction effect, and physical and biological mixing.210 Pb ex Dating method, 239, 240 The characteristic peaks of the Pu time-scale method are pulse inputs, which have stronger anti-interference capabilities and indicate the characteristic age of a specific sedimentary layer more accurately. However, it does not have the continuity of sedimentary age indication and can only constrain a few typical time points.

[0005] In the application of short-timescale dating of travertine sediments, due to 210 Pb ex Dating methods are significantly affected by factors such as disturbances, resulting in substantial dating errors. Therefore, in practical research applications, errors often occur in travertine deposits. 239, 240 The age indicated by the Pu characteristic peaks and 210 Pb ex Inconsistent dating results exist. Therefore, methods indicating the age of travertine deposits are needed for more accurate dating. 239, 240 Pu is used as a characteristic time marker to correct for age continuity, but it is more susceptible to perturbations. 210 Pb ex The age data obtained by the dating method will be able to improve... 210 Pb ex The accuracy of the dating results. Currently, regarding "utilizing..." 239, 240 Pu corrects travertine deposition over a nearly century-scale period. 210 Pb ex Quantitative studies on "dating results" have not yet been reported, even if simultaneous dating of the same sediment sample exists. 210 Pb and 239, 240 Studies of Pu data have only involved simple comparative analysis without mutual coupling correction.

[0006] Currently, in the study of travertine or other sedimentary chronology on a timescale of nearly 100 years, a single dating tool is often used. Even when multiple dating tools are used, only a simple comparative analysis of the results obtained from different dating tools is performed. There is no organic coupling and mutual calibration of the two dating tools in the same travertine sample. Summary of the Invention

[0007] The object of this invention is to overcome at least one of the aforementioned shortcomings of the prior art. For example, one object of this invention is to provide a method utilizing plutonium isotopes ( 239, 240 Pu) Correction of travertine deposits over a nearly century-scale 210 Pb ex Dating method.

[0008] To achieve the above objectives, this invention provides a method for correcting nearly century-long travertine deposits using plutonium isotopes. 210 Pb ex A method for determining the year, the method comprising: 1) Perform stratified sampling of sediment cores and record the deposition depth x of each vertical layer sample; 2) After pretreatment, samples from each layer are tested to obtain test data. Based on the test data, the parameters of each layer sample are calculated. 210 Pb ex Specific activity; 3) Samples from each layer were digested, separated, purified, and then tested. 239 Pu、 240 Calculate the number of Pu atoms in each layer of the sample. 239, 240 Pu specific activity, observed at different strata 239, 240 Pu specific activity, find the travertine deposition depth x1 corresponding to the maximum peak value; 4) Drawing 210 Pb ex From the nonlinear fitting curve of the exponential decay function between specific activity and sedimentation depth, the dating equation y of the nonlinear fitting curve of the exponential decay function is obtained. A Through the dating equation y A Calculate the deposition rate V1 and the deposition depth h1 for the target year; 5) Compare whether h1 and x1 are consistent. If h1 ≠ x1, then modify the year equation y. A Perform correction; 6) Tested based on samples at surface deposition depth x0 210 Pb ex Specific activity value y0, through 210 The decay equation of Pb over time, A （x） Calculate the target year 239, 240 Theoretical Pu peak layer depth x1 210 Pb ex Specific activity value y1; 7) Based on the obtained x0, y0, x1, and y1, apply the year-determining equation y A By applying constraints, a new dating equation y is obtained. B ; 8) Through the year-determining equation y B Calculate the corrected deposition rate V2 and the corresponding deposition age for each layer.

[0009] Alternatively, the stratified sampling of the sediment column in step 1) specifically refers to: selecting the same travertine sediment column, performing stratified sampling of the sediment column, and collecting travertine sediment samples from different strata depths for use. 210 Pb, 239, 240 Pu experimental analysis and testing.

[0010] Alternatively, the pretreatment described in step 2) may include freeze drying, grinding, and homogenization.

[0011] Optionally, the experimental tests described in step 2) are performed to obtain test data, including experimental measurements using a well-type high-purity germanium gamma spectrometer to obtain energy spectrum diagrams at each layer, and recording the energy spectrum at each layer. 210 Pb (46.5 keV), 214 Pb (351.9 keV) 214 The counting peak of Bi (609.3 keV), the peak area after deducting the background (net count), the real-time measurement time of the sample, the detector efficiency curve (absolute detection efficiency at the 46.5 keV energy point), the self-absorption correction factor and the geometric correction factor, and the sample mass.

[0012] Alternatively, step 2) involves calculating the samples at each layer based on the test data. 210 Pb ex Specific activity includes: Through formula Calculate the total number of samples from each layer. 210 Pb activity, where A tot For the total 210 Pb activity, R is net count rate, ε is detector efficiency, P γ f is the emission probability of γ-rays at 46.5 keV. SA f is the self-absorption correction factor. geom It is a geometric correction factor; Through formula Calculate the total number of samples from each layer. 210 Pb specific activity, where C tot For the total 210 Pb specific activity, where m is the sample mass; pass Calculate the excess samples for each layer 210 Pb specific activity, where C ex (x) represents the excess at a deposition depth of x. 210 Pb specific activity, C tot (x) represents the total sediment at depth x. 210 Pb specific activity, C sup (x) represents the supported state at a deposition depth x. 210 Pb specific activity; Among them, obtained through testing 214 Pb, 214 The gamma peak of Bi can be used to infer... 226 Ra, under radioactive equilibrium conditions, supported state 210 Pb specific activity C sup equal 226 Ra activity.

[0013] Alternatively, the test described in step 3) 239 Pu、 240The atomic number of Pu was determined using high-resolution inductively coupled plasma mass spectrometry.

[0014] Alternatively, step 3) may be used to calculate the samples at each stratum. 239, 240 Pu specific activity includes: Through formula Calculate the position of each layer 239, 240 Pu activity, where A x At a deposition depth x 239, 240 Pu activity, λ x The decay constant of plutonium isotopes (λ) 239 It is 9.1×10 -6 a -1 ;λ 240 1.06×10 -4 a -1 ), N x The number of plutonium isotopes at a deposition depth x; Through formula Calculate the samples of each layer 239, 240 Pu specific activity, where C x At a deposition depth x 239, 240 Pu specific activity, A x At a deposition depth x 239, 240 Pu activity, where m is the sample mass; The maximum peak value corresponds to the travertine deposition depth x1, which represents 1963. 239, 240 The deposition depth x1 corresponding to the Pu feature timescale.

[0015] Alternatively, the drawing described in step 4) 210 Pb ex The nonlinear fitting curve of the exponential decay function between specific activity and deposition depth is plotted with the deposition depth of travertine as the x-axis and y-axis as the nonlinear fitting curve. 210 Pb ex Specific activity is represented by the ordinate y, and the specific activity of each travertine layer sample is... 210 Pb ex Plot the specific activity and sedimentation depth data points onto a coordinate system and draw a graph. 210 Pb ex Nonlinear fitting curve of exponential decay function between specific activity and deposition depth.

[0016] Alternatively, the dating equation y described in step 4) A for , where y A For the deposition depth x 210 Pb ex Specific activity, in dpm / g; x is the depositional depth calculated from the surface of the travertine deposit, in cm; A a For the surface layer of sediments210 Pb ex Specific activity, expressed in dpm / g; t a The attenuation characteristic depth parameter, physically representing the "characteristic scale" of the attenuation of nuclide activity in sediments with depth; y a As the background 210 Pb ex Specific activity, expressed in dpm / g.

[0017] Alternatively, the calculation of the deposition rate V1 in step 4) can be performed using a dating equation. The parameter t in a Substitute into the equation The calculation yields λ, where λ is 210 The decay constant of Pb is λ≈0.0311a. -1 ; Alternatively, step 4) of calculating the deposition depth h1 for the target year includes: by The depositional age Δt between the travertine sampling time and 1963 was calculated using... The depositional depth h1 in 1963 was calculated, where t0 is the sampling year and t 1963 The target year is 1963.

[0018] Alternatively, as described in step 6) 210 decay equation of Pb over time , where A （x） At the deposition depth x layer 210 Pb ex Specific activity, in dpm / g; A0 is the measured value at the surface layer. 210 Pb ex Specific activity (A0=y0), in dpm / g; Δt is the depositional age between the sampling time and 1963, in years; the target year for calculation is 1963. 239, 240 Theoretical Pu peak layer depth x1 210 Pb ex Specific activity value .

[0019] Alternatively, in step 7), the annual equation y is modified based on the obtained x0, y0, x1, and y1. A The constraint is applied to force the fitted curve to pass through the measured point (x0, y0) of the travertine surface sediments and the corresponding theoretical point (x1, y1) in 1963; the new dating equation .

[0020] Alternatively, step 8) can be performed using the dating equation y. B The corrected deposition rate V2 and the corresponding deposition age for each layer are calculated using the dating equation. Given data t b Substitute it into the equation The corrected deposition rate V2 is calculated; the corrected deposition age t for each layer is calculated by t=x / V2, where t is the corrected deposition age for each layer, x is the deposition depth, and V2 is the corrected deposition rate.

[0021] Compared with the prior art, the beneficial effects of the present invention include at least one of the following: (1) This invention uses the plutonium isotope characteristic time-scale method in travertine deposition dating, providing a new method for travertine deposition dating on a scale of nearly 100 years.

[0022] (2) This invention utilizes pulse input from the same travertine sample. 239, 240 Pu peak timescale is used to correct for successive deposition and decay. 210 Pb specific activity and deposition depth constructed a " 210 Pb ex The nonlinear fitting curve dating equation of the "specific activity (dpm / g) - deposition depth (cm)" exponential decay function will improve the accuracy of travertine deposition age results at the centennial scale, help to accurately calculate travertine deposition rate, and quantify the spatiotemporal differences of the deposition process.

[0023] (3) The correction method of the present invention is in 210 Pb ex Based on the dating method, adopt 239, 240 The Pu feature timescale is corrected, which is convenient, simple, and does not require repeated sampling. Attached Figure Description

[0024] The above and other objects and / or features of the present invention will become clearer from the following description taken in conjunction with the accompanying drawings, in which: Figure 1 The following is an example of Huanglong calcite from Example 1 of the present invention. 210 Pb ex The relationship between radioactivity and depth is shown in the graph.

[0025] Figure 2 The following diagram illustrates the various layers of the Huanglong travertine deposits in Example 1 of this invention. 239, 240 Pu activity level.

[0026] Figure 3 Example 1 of the present invention is shown. 239, 240 Pu on travertine deposits over a period of nearly a century 210 Pb ex Correction curves for dating. Detailed Implementation

[0027] In the following sections, an embodiment of the present invention will be described in detail with reference to exemplary embodiments, including a method for correcting nearly 100-year-scale travertine deposition using plutonium isotopes. 210 Pb ex Dating method.

[0028] Based on the existing problems, this invention innovatively utilizes pulsed input from the same travertine sample. 239, 240 Pu peak timescale is used to correct for successive deposition and decay. 210 Pb ex The relationship between specific activity and sedimentation depth 210 Pb ex The nonlinear fitting curve dating equation of the "specific activity (dpm / g) - sedimentation depth (cm)" exponential decay function improves the accuracy of travertine deposition age results at the centennial scale. This will help to accurately calculate travertine deposition rates, quantify the spatiotemporal differences in depositional processes, reconstruct regional paleoclimate evolution sequences, reveal climate fluctuation patterns, trace regional environmental change history, identify signals of human activities and natural disturbances, support comparative studies of cross-carrier sedimentary records, and construct a comprehensive regional environmental evolution framework.

[0029] This invention adopts the following approach: the travertine deposit is cut along the growth axis, and samples are taken from top to bottom in layers (recording the deposition depth at each layer) for further analysis. 210 Pb and 239, 240 Pu experiment pretreatment, pretreated 210 Pb and 239, 240 The PU samples were tested on the machine to obtain data at different layers. 210 Pb and 239 Pu、 240 Pu test data, calculate the corresponding 210 Pb ex and 239, 240 Pu activity. According to... 210 Pb ex The pattern of specific activity decreasing with sedimentation depth was plotted. 210 Pb ex The nonlinear fitting curve of the exponential decay function of specific activity (dpm / g) versus sedimentation depth (cm) yields the dating equation y. A ( (where y) A : The sedimentation depth x corresponds to 210 Pb ex Specific activity, in dpm / g; x: sedimentary depth calculated from the surface of the travertine deposit, in cm; A a : travertine deposits on the surface 210 Pb ex Specific activity, expressed in dpm / g and t aThe attenuation characteristic depth parameter, whose physical meaning is the "characteristic scale" of the attenuation of nuclide activity in sediments with depth, y a Background 210 Pb ex Specific activity, in units of (dpm / g), is used to determine the dating equation (y) using a fitted curve. A ( The attenuation characteristic depth parameter (t) in )) a ), and substitute it into the equation (λ: 210 The decay constant of Pb is λ≈0.0311a. -1 The deposition rate (V1) is calculated using the formula. (t0: sampling year, t) 1963 The depositional age (Δt) between the travertine sampling time and 1963 is calculated using the target year (1963). Then, the depositional rate (V1) and depositional age (Δt) are used to calculate the depositional age using the formula... The travertine deposition depth h1 corresponding to 1963 was calculated. Then, based on the measured... 239, 240 Pu specific activity data were used to obtain the vertical distribution characteristics and characteristic peaks of plutonium isotope composition in travertine cores. The corresponding depositional depth was determined using these characteristic peaks, which is the depth value x1 at the time of travertine deposition in 1963. A comparative analysis was then performed on the depositional depths corresponding to 1963 using two dating methods (i.e., h1 vs. x1). If the depositional depths at 1963 were found to be inconsistent (i.e., h1 ≠ x1), then further analysis was needed. 239, 240 The characteristic time stamp of 1963 obtained from the Pu peak signal is " 210 Pb ex The dating equation for the exponential decay function of specific activity (dpm / g) versus sedimentation depth (cm) was corrected to obtain a new dating equation for the fitting curve y. B ( Then, using the new fitting curve dating equation y B ( ) Calculate the corrected deposition rate (V2) and the corresponding deposition age (t) for each layer.

[0030] use 239, 240 Pu Correction" 210 Pb ex The principle of the dating equation based on the nonlinear fitting curve of the "specific activity (dpm / g) - sedimentation depth (cm)" exponential decay function: The original method utilizes sample depth and measurement 210 Pb ex The "comparison of activity" 210 Pb exThe dating equation for the exponential decay function nonlinear fitting curve of specific activity (dpm / g) – sedimentation depth (cm) is y. A ( ).because 210 Pb is affected by factors such as bioturbation, sediment compaction, and grain size effects, and may exhibit [various effects]. 210 The migration of Pb to upper or lower sediment layers leads to the acquisition of 210 Pb ex It may not have originated entirely from in-situ sedimentation; it may have included sediments that migrated from other strata after sedimentation. 210 Pb, leading to 210 Pb ex Too large; or perhaps on a certain level 210 Pb migrates to other layers, resulting in 210 Pb ex The value is too small, thus causing the obtained original exponential decay function nonlinear fitting curve dating equation y to be too small. A ( Inaccurate dating methods lead to unreliable dating results for travertine deposits. This is because the sediments formed in 1963 contain... 239, 240 The characteristic peak of Pu is a pulse input, and its influence from the layers above and below the peak is relatively small. Even if Pu migration occurs, it mainly affects the magnitude of the peak height and does not significantly affect the depositional depth of the peak layer, thus exhibiting stronger resistance to interference. Furthermore, in travertine surface sediments... 210 Because Pb has a relatively short formation time, it is less affected by factors such as compaction and disturbance, hence the measured values ​​on the sediment surface are... 210 Pb ex The specific activity value (A0) is also relatively reliable. Therefore, it can be used for the surface layer (present-day sediments) of travertine deposits. 210 Pb ex Specific activity points and 239, 240 The theory derived by Pu's characteristic timescale (1963) 210 Pb ex Specific activity points are used to correct the original based 210 Pb ex The " 210 Pb ex Specific activity (dpm / g) — sedimentation depth (cm) “Exponential decay function nonlinear fitting curve dating equation y A ( ).

[0031] The deposition depth (x0) was taken as the stratigraphic level of the travertine surface deposits, and samples were taken from this stratigraphic level. 210 Pb ex Specific activity tests were conducted to obtain the measured travertine surface deposits. 210 Pbex Specific activity (y0) in determining travertine deposits in 1963 239, 240 After determining the layer and depth (x1) where the Pu peak occurs, radioactive isotopes can be used ( 210 Pb ex Attenuation formula (A) （x） : Deposition depth x layer 210 Pb ex Specific activity, A0: measured at the surface layer 210 Pb ex Specific activity (A0=y0), λ: decay constant (λ≈0.0311a) -1 (Δt: sedimentary age between sampling time and 1963) to estimate the theoretical age of the stratigraphic position at 1963. 210 Pb ex Value (y1). This theory 210 Pb ex The value (y1) represents the theoretical value that travertine deposits at this depth (x1) should have. 210 Pb ex Specific activity value, which is compared with the measured value of travertine surface sediments at deposition depth (x0). 210 Pb ex Specific activity value (y0) is used together to correct the original " 210 Pb ex Specific activity (dpm / g) — sedimentation depth (cm) "exponential decay function nonlinear fitting curve dating equation y A ( Therefore, based on this, we refit " 210 Pb ex The specific activity (dpm / g) - sedimentation depth (cm) curve was plotted, and the surface sedimentation depth (x0) and the corresponding surface sediments at that layer were measured. 210 Pb ex Value (y0), formed in 1963 239, 240 The depositional depth (x1) indicated by the Pu peak signal and the theoretical value corresponding to the calculated characteristic timescale of 1963. 210 Pb ex By constraining the value (y1), a new exponential decay function nonlinear fitting curve dating equation y is obtained. B ( The dating equation y is determined by nonlinear fitting of the newly obtained exponential decay function curve. B ( This allows for the calculation of the corrected sedimentation rate V2 and the corresponding sedimentation age for each layer, thereby increasing the accuracy of travertine deposition on a near-century-scale. 210 Pb ex The accuracy of sedimentary age results obtained through dating.

[0032] Exemplary Example 1 This exemplary embodiment provides a method for utilizing plutonium isotopes ( 239, 240 Pu) Correction of travertine deposits over a nearly century-scale 210 Pb ex A method for determining the year, the method may include: S1. Perform stratified sampling of the sediment column and record the deposition depth x of each vertical layer sample.

[0033] In this embodiment, the stratified sampling of the sediment column specifically involves: selecting the same travertine sediment column, performing stratified sampling of the sediment column, and collecting travertine sediment samples from different strata depths for use in... 210 Pb, 239, 240 Pu experimental analysis and testing.

[0034] S2. After pretreatment of the samples from each layer, experimental tests are conducted to obtain test data. Based on the test data, calculations are performed on the samples from each layer. 210 Pb ex Compared to activity.

[0035] In this embodiment, the pretreatment includes freeze drying, grinding, and homogenization.

[0036] In this embodiment, the experimental testing and data acquisition include using a well-type high-purity germanium gamma spectrometer to obtain energy spectrum diagrams at each layer and record the energy distribution at each layer. 210 Pb (46.5 keV), 214 Pb (351.9 keV) 214 The counting peak of Bi (609.3 keV), the peak area after deducting the background (net count), the real-time measurement time of the sample, the detector efficiency curve (absolute detection efficiency at the 46.5 keV energy point), the self-absorption correction factor and the geometric correction factor, and the sample mass.

[0037] In this embodiment, the calculation of samples at each layer... 210 Pb ex Specific activity includes: Through formula Calculate the total number of samples from each layer. 210 Pb activity, where A tot For the total 210 Pb activity, R is net count rate, ε is detector efficiency, P γ f is the emission probability of γ-rays at 46.5 keV. SA f is the self-absorption correction factor. geom It is a geometric correction factor; Through formula Calculate the total number of samples from each layer.210 Pb specific activity, where C tot For the total 210 Pb specific activity, where m is the sample mass; pass Calculate the excess samples for each layer 210 Pb specific activity, where C ex (x) represents the excess at a deposition depth of x. 210 Pb specific activity, C tot (x) represents the total sediment at depth x. 210 Pb specific activity, C sup (x) represents the supported state at a deposition depth x. 210 Pb specific activity; Among them, obtained through testing 214 Pb, 214 The gamma peak of Bi can be used to infer... 226 Ra, under radioactive equilibrium conditions, supported state 210 Pb specific activity C sup equal 226 Ra activity.

[0038] S3. After digestion, separation, and purification of samples from each layer, testing is performed. 239 Pu、 240 Calculate the number of Pu atoms in each layer of the sample. 239, 240 Pu specific activity, observed at different strata 239, 240 Pu specific activity was used to find the travertine deposition depth x1 corresponding to the maximum peak value.

[0039] The test described in this embodiment 239 Pu、 240 The atomic number of Pu was determined using high-resolution inductively coupled plasma mass spectrometry.

[0040] In this embodiment, the calculation of samples at each layer... 239, 240 Pu specific activity includes: Through formula Calculate the position of each layer 239, 240 Pu activity, where A x At a deposition depth x 239, 240 Pu activity, λ x The decay constant of plutonium isotopes (λ) 239 9.1×10 -6 a -1 ;λ 240 1.06×10 -4 a -1 ), N x The number of plutonium isotopes at a deposition depth x; Through formula Calculate the samples of each layer239, 240 Pu specific activity, where C x At a deposition depth x 239, 240 Pu specific activity, A x At a deposition depth x 239, 240 Pu activity, where m is the sample mass.

[0041] In this embodiment, the travertine deposition depth x1 corresponding to the maximum peak value refers to 1963. 239, 240 The deposition depth x1 corresponding to the Pu timescale.

[0042] S4, Drawing 210 Pb ex From the nonlinear fitting curve of the exponential decay function between specific activity and sedimentation depth, the dating equation y of the nonlinear fitting curve of the exponential decay function is obtained. A Through the dating equation y A Calculate the deposition rate V1 and the deposition depth h1 for the target year.

[0043] In this embodiment, the drawing 210 Pb ex The nonlinear fitting curve of the exponential decay function between specific activity and deposition depth is plotted with the deposition depth of travertine as the x-axis and y-axis as the nonlinear fitting curve. 210 Pb ex Specific activity is represented by the ordinate y, and the specific activity of each travertine layer sample is... 210 Pb ex Plot the specific activity and sedimentation depth data points onto a coordinate system and draw a graph. 210 Pb ex Nonlinear fitting curve of exponential decay function between specific activity and deposition depth (cm).

[0044] In this embodiment, the year-determining equation y A for , where y A For the deposition depth x 210 Pb ex Specific activity, in dpm / g; x is the depositional depth calculated from the surface of the travertine deposit, in cm; A a For the surface layer of sediments 210 Pb ex Specific activity, expressed in dpm / g; t a The attenuation characteristic depth parameter, physically representing the "characteristic scale" of the attenuation of nuclide activity in sediments with depth; y a As the background 210 Pb ex Specific activity, expressed in dpm / g.

[0045] In this embodiment, the deposition rate V1 is calculated using a dating equation. The parameter t in a Substitute into the equation The calculation yields λ, where λ is 210 The decay constant of Pb is λ≈0.0311a. -1 .

[0046] In this embodiment, calculating the deposition depth h1 of the target year includes: through The depositional age Δt between the travertine sampling time and 1963 was calculated using... The depositional depth h1 in 1963 was calculated, where t0 is the sampling year and t 1963 The target year is 1963.

[0047] S5. Compare whether h1 and x1 are consistent. If h1 ≠ x1, then modify the year equation y. A Perform corrections.

[0048] S6. Based on the test of the sample at the surface deposition depth x0. 210 Pb ex Specific activity value y0, through 210 The decay equation of Pb over time, A （x） Calculate the target year 239, 240 Theoretical Pu peak layer depth x1 210 Pb ex Specific activity value y1.

[0049] In this embodiment, the 210 The decay equation of Pb over time is: , where A （x） At the deposition depth x layer 210 Pb ex Specific activity, in dpm / g; A0 is the measured value at the surface layer. 210 Pb ex Specific activity (A0=y0), in dpm / g; Δt is the depositional age between the sampling time and 1963, in years; the target year for calculation. 239, 240 Theoretical Pu peak layer depth x1 210 Pb ex Specific activity value .

[0050] S7. Based on the obtained x0, y0, x1, and y1, apply the year-determining equation y A By applying constraints, a new dating equation y is obtained. B .

[0051] In this embodiment, the process of applying the obtained x0, y0, x1, and y1 to the year-determining equation y AConstraints were applied to force the fitted curve to pass through the measured point (x0, y0) of the travertine surface sediments and the corresponding theoretical point (x1, y1) in 1963; this yielded a new dating equation. .

[0052] S8, using the year-determining equation y B Calculate the corrected deposition rate V2 and the corresponding deposition age t for each layer.

[0053] In this embodiment, the step of using the year-determining equation y B The corrected deposition rate V2 and the corresponding deposition age t for each layer are calculated using the dating equation. Given data t b Substitute it into the equation The corrected deposition rate V2 is calculated; the corrected deposition age for each layer is calculated using t=x / V2 (t is the corrected deposition age for each layer, x is the deposition depth, and V2 is the corrected deposition rate).

[0054] Exemplary Example 2 The technical problem to be solved by this exemplary embodiment is: to provide a method for utilizing pulse input from the same travertine sample. 239, 240 Pu peak timescale is used to correct for successive deposition and decay. 210 Pb ex The relationship between specific activity and sedimentation depth 210 Pb ex A method using a nonlinear fitting curve of the "specific activity (dpm / g) - sedimentation depth (cm)" exponential decay function to determine the dating equation was developed, thereby improving the dating accuracy of travertine deposits on a near-century-scale. 210 Pb ex The accuracy and reliability of the dating results.

[0055] This exemplary embodiment adopts the following technical solution and may include the following steps: First, select the same travertine sediment column and perform stratified sampling to collect travertine sediment samples from different depths for use in [further processing]. 210 Pb, 239, 240 The depth (x) of each vertically layered sample was determined and recorded using Pu experiments.

[0056] Second, after drying and grinding the collected layered samples, experimental measurements were performed using a well-type high-purity germanium gamma-ray spectrometer to obtain energy spectra at different layers, and the energy of each layer was recorded. 210 Pb (46.5 keV), 214 Pb (351.9 keV) 214The counting peaks of Bi (bismuth-214, 609.3 keV); peak area after background subtraction (net count); real-time measurement time of the sample; detector efficiency curve (absolute detection efficiency at 46.5 keV energy point); self-absorption correction factor and geometric correction factor; sample mass and other data.

[0057] Third, through equations (A) tot :total 210 Pb activity, R: net count rate (after background subtraction), ε: detector efficiency, P γ Emission probability of 46.5 keV gamma rays, f SA Self-absorption correction factor, f geom (Geometric correction factor) Calculates the total for each stratified sample 210 Pb activity. Then, the formula is used... (where C) tot :total 210 Pb specific activity (m: sample mass) was used to calculate the total Pb activity of each stratified sample. 210 Pb specific activity. Obtained by measurement. 214 Pb, 214 The gamma peak of Bi can be used to infer... 226 Ra, under radioactive equilibrium conditions, supported state 210 Pb specific activity (C) sup )equal 226 Ra specific activity. (From) (where C) ex (x): Excess sedimentation at depth x 210 The excess Pb specific activity was used to calculate the specific activity of each stratified sample. 210 Pb ( 210 Pb ex ) activity.

[0058] Fourth, the measurement 210 Pb ex After specific activity determination, the stratified travertine sediment samples were pretreated by digestion, separation and purification, and then analyzed by high-resolution inductively coupled plasma mass spectrometry. 239 Pu、 240 Number of atoms of Pu (N) x ), using activity (A x )Calculate the equation (λ) x : Decay constant of plutonium isotopes; λ 239 =9.1×10 -6 a -1 ;λ 240 =1.06×10 -4 a -1 N x Number of atoms of plutonium isotopes (N)239Pu N 240Pu )) Calculate the position of each layer 239, 240 Pu activity (A x ); using specific activity (C x ) Calculate the equation (m: sample mass) can be used to calculate the mass of samples from each layer. 239, 240 Pu activity level.

[0059] Fifth, the depositional depth of travertine is used as the abscissa (x) and 210 Pb ex Specific activity is used as the ordinate (y), and each travertine stratified sample is plotted. 210 Pb ex Plot the specific activity and sedimentation depth data points onto a coordinate system and draw a graph. 210 Pb ex From the nonlinear fitting curve of the exponential decay function between specific activity and sedimentation depth, the dating equation y of the nonlinear fitting curve of the exponential decay function is obtained. A ( (where y) A : The sedimentation depth x corresponds to 210 Pb ex Specific activity, in dpm / g; x: sedimentary depth calculated from the surface of the travertine deposit, in cm; A a : Sediment surface 210 Pb ex Specific activity, expressed in dpm / g and t a The attenuation characteristic depth parameter, physically representing the "characteristic scale" of nuclide activity attenuation with depth in sediments, y a Background 210 Pb ex Specific activity, expressed in dpm / g.

[0060] Sixth, through the year-determining equation (y A ( The parameter t in )) a Substitute it into the equation (λ: 210 The decay constant of Pb is λ≈0.0311a. -1 The deposition rate V1 was calculated from the data. Seventh, through (t0: sampling year, t) 1963 : Calculate the depositional age (Δt) between the travertine sampling time and 1963 (target year), using... The deposition depth h1 in 1963 was calculated.

[0061] Eighth, observe different layers. 239, 240Pu specific activity was used to find the travertine deposition depth corresponding to the maximum peak value, which refers to the depth in 1963. 239, 240 The deposition depth x1 corresponding to the Pu timescale.

[0062] Ninth, comparative utilization 210 Pb ex Fixed-year method and 239, 240 The Pu time-scaled method is used to determine whether the travertine deposition depths (h1 and x1) obtained in 1963 are consistent; if h1 ≠ x1, further investigation is needed. 210 Pb ex The exponential decay function obtained by the dating method has a nonlinear fitting curve, and the dating equation is y. A ( (The correction is performed.)

[0063] Tenth, measurements were performed using surface sediment samples at the travertine deposition depth (x0). 210 Pb ex Specific activity value (y0), through 210 decay equation of Pb over time (A) （x） : Deposition depth x layer 210 Pb ex Specific activity, in units of (dpm / g), A0: measured at the surface layer. 210 Pb ex Specific activity (A0=y0), unit is (dpm / g); λ: decay constant (λ≈0.0311a). -1 Δt: the sedimentary age between the sampling time and 1963, in years (a). The 1963 year was calculated. 239, 240 Theoretical depth at peak Pu layer (x1) 210 Pb ex Specific activity value .

[0064] Eleventh, using the depth (x0) of the surface sediment layer and the measured values ​​of that layer... 210 Pb ex Specific activity value (y0), the theoretical value corresponding to 1963 calculated 210 Pb ex Specific activity value (y1) and 1963 239, 240 The maximum peak depth of Pu (x1) was measured in the layered sample. 210 Pb ex The curve fitting process of specific activity (y) versus sedimentation depth (x) is constrained to force the fitted curve to pass through the measured point (x0, y0) of travertine surface sediments and the theoretical point (x1, y1) corresponding to 1963, thereby obtaining a new exponential decay function nonlinear fitting curve dating equation y B ( ).

[0065] Twelfth, through the year-determining equation (y B ( Given data t in )) b Substitute it into the equation (λ: 210 The decay constant of Pb is λ≈0.0311a. -1 The corrected deposition rate V2 is calculated in the formula; the corrected deposition age t for each layer is calculated by t=x / V2, where t is the corrected deposition age for each layer, x is the deposition depth, and V2 is the corrected deposition rate.

[0066] To better understand the exemplary embodiments of the present invention described above, further explanation is provided below with reference to specific examples.

[0067] Example 1 This example illustrates a method for utilizing plutonium isotopes (as described in this invention) 239, 240 Pu) Correction of travertine deposits over a nearly century-scale 210 Pb ex The method for determining the year is applied, and the steps include: Step 1: In 2023, fresh travertine column samples were collected from the continuous deposits in the Zhongsi area of ​​the Huanglong Travertine Scenic Area. The travertine was cut along the growth axis using a cutting machine, and 19 travertine sediment samples were collected from the top to the bottom at depths of 0.15cm, 1cm, 2.5cm, 4.5cm, 5cm, 5.5cm, 6.5cm, 7cm, 8cm, 8.5cm, 9cm, 9.5cm, 10cm, 11.5cm, 12.5cm, 14.5cm, 17.5cm, 23cm, and 29cm. 210 Pb, 239, 240 The depth (x) of each vertically layered sample was determined and recorded using Pu experiments.

[0068] Step 2: After drying and grinding the collected layered samples, proceed with... 210 Pb sample pretreatment (specific procedures are described in section (1) of "Sample Pretreatment and Testing" below). 210 (Pb pretreatment and testing), followed by experimental measurements using a well-type high-purity germanium gamma-ray spectrometer to obtain energy spectra at different strata, and recording the values ​​at each stratum. 210 Pb (46.5 keV), 214 Pb (351.9 keV) 214Bi (bismuth-214, 609.3 keV) count peak; peak area after background subtraction (net count); real-time measurement time of the sample; detector efficiency curve (absolute detection efficiency at 46.5 keV energy point); self-absorption correction factor and geometric correction factor; sample mass and other data.

[0069] Step 3: Through equations (A) tot :total 210 Pb activity, R: net count rate (after background subtraction), ε: detector efficiency, P γ Emission probability of 46.5 keV gamma rays, f SA Self-absorption correction factor, f geom (Geometric correction factor) Calculates the total for each stratified sample 210 Pb activity. Then, the formula is used... (where C) tot :total 210 Pb specific activity (m: sample mass) was calculated for total Pb activity at each stratified sample. 210 Pb specific activity. Obtained by measurement. 214 Pb, 214 The gamma peak of Bi can be used to infer... 226 Ra, under radioactive equilibrium conditions, supported state 210 Pb specific activity (C) sup )equal 226 Ra specific activity. (From) (where C) ex (x): Excess at sedimentation depth x 210 The excess Pb specific activity was used to calculate the specific activity of each stratified sample. 210 Pb specific activity, excess activity of samples from each layer 210 Pb ( 210 Pb ex The specific activity was determined, and the results are shown in Table 1.

[0070] Step 4: Measure 210 Pb ex After specific activity testing, the stratified travertine sediment samples were subjected to digestion, separation and purification pretreatment (specific operations are described in "Sample Pretreatment and Testing" (2) Pu isotope pretreatment and testing) and determined by high-resolution inductively coupled plasma mass spectrometry. 239 Pu、 240 Number of atoms of Pu (N) x ); using activity (A) x )Calculate the equation (λ) x : Decay constant of plutonium isotopes; λ 239 =9.1×10 -6 a -1 ;λ240 =1.06×10 -4 a -1 N x Number of atoms of plutonium isotopes (N) 239Pu N 240Pu )) Calculate the position of each layer 239, 240 Pu activity; utilizing specific activity (C) x ) Calculate the equation (m: sample mass) can be used to calculate the mass of samples from each layer. 239, 240 Pu specific activity, samples from different layers 239, 240 The specific activity of Pu is shown in Table 1.

[0071] Sample pretreatment and testing: (1) 210 Pb pretreatment and testing: After freeze-drying, grinding, and homogenizing the sample, weigh 15-20g and place it in a standard round sample box. Seal the sample box tightly and leave it for more than 20 days. This is to allow the sample to settle. 210 To ensure measurement accuracy, Pb is brought into radioactive equilibrium with its short-lived daughter particles. The sample is then placed on the probe (center position) within the lead chamber of the gamma spectrometer, the lead chamber is closed, and the sample is measured according to the experimental procedures. The measurement period is set to 4-5 days to obtain sufficient counts and reduce statistical errors.

[0072] (2) Pretreatment and testing of Pu isotopes: Measurement 210 Pb ex Weigh approximately 6g of the stratified travertine sediment sample after specific activity determination and add it to... 242 Pu-labeled samples were digested by heating in 30 ml of concentrated nitric acid for approximately 4 hours, filtered, and then adjusted to 8 M HNO3 with deionized water. Approximately 0.5 g of NaNO2 was added to each sample to adjust the valence state of Pu, and the samples were heated on a hot plate (40°C) for 50 minutes. The samples were then purified twice by column chromatography. After evaporation to dryness on a hot plate (180°C), 1 ml of ultra-high purity HNO3 (68%) was added, and the mixture was evaporated to near dryness. Finally, the samples were dissolved in 1 ml of 4% ultra-high purity HNO3 and transferred to 2 ml sample vials for analysis. High-resolution inductively coupled plasma mass spectrometry (HR-ICP-MS) was then used for sample analysis.

[0073] Table 1. Huanglong travertine sediment samples 210 Pb ex , 239, 240 Pu Specific Activity Data Table

[0074] Step 5: Plot the deposition depth of travertine as the x-axis and... 210 Pb ex Specific activity is used as the ordinate (y), and each travertine stratified sample is plotted. 210 Pb ex Specific activity and sedimentation depth data points are projected onto a coordinate system to plot " 210 Pb ex The nonlinear fitting curve of the exponential decay function between specific activity and deposition depth (cm), as shown in... Figure 1 As shown, the exponential decay function nonlinear fitting curve dating equation y is obtained. A ( ).

[0075] Step 6: Using the year-determining equation (y A ( The known parameter t in )) a =4.822, substitute it into the equation (λ: 210 The decay constant of Pb is λ≈0.0311a. -1 The deposition rate was calculated in ) .

[0076] Step 7: Through (Where t0=2023, the sampling time of Huanglong travertine) The depositional age between the travertine sampling time and 1963 was calculated to be 60 years. The sedimentation depth in 1963 was calculated to be h1 = 9 cm.

[0077] Step 8: In Figure 2 Observe different layers 239, 240 Pu specific activity, indicated by the red box. 239, 240 Pu specific activity sedimentation peak value, at the peak value 239, 240 A Pu specific activity of 1.219 mBq / g corresponds to a travertine deposition depth x1 of 9.5 cm, representing the 1963 terrane deposit. 239, 240 The deposition depth corresponding to the Pu timescale is x1 = 9.5 cm.

[0078] Step 9: Since h1 = 9cm ≠ x1 = 9.5cm, it is necessary to... 210 Pb ex The exponential decay function obtained by the dating method has a nonlinear fitting curve, and the dating equation is y. A ( (The correction is performed.)

[0079] Step 10: Measured data using travertine surface sediment samples. 210 Pb ex Specific activity value (A0 = 3.44 dpm / g), through 210decay equation of Pb over time Calculate 1963 239, 240 Theoretical peak depth of Pu (x1=9.5cm) 210 Pb ex Specific activity value y1 (y1=A) (9.5) =0.53 dpm / g).

[0080] Step 11: Using the depth x0 (x0=0.15cm) of the surface sediment layer and the measured values ​​at that layer... 210 Pb ex Specific activity value y0 (y0=3.44 dpm / g), calculated theoretical value corresponding to 1963 210 Pb ex Specific activity value y1 (y1=0.53 dpm / g) and 1963 239, 240 The maximum peak depth of Pu, x1 (x1=9.5cm), was measured on the layered sample. 210 Pb ex The curve fitting process of specific activity (y) versus sedimentation depth (x) is constrained to force the fitted curve to pass through the measured point (x0, y0) = (0.15, 3.44) of travertine surface sediments and the corresponding theoretical point (x1, y1) = (9.5, 0.53) in 1963, thereby obtaining a new exponential decay function nonlinear fitting curve dating equation y B ( The fitted curves before and after correction are as follows: Figure 3 As shown, Figure 3 The black line represents the original fitted curve, and the red line represents the corrected fitted curve.

[0081] Step 12: Using the year-determining equation (y B ( The parameter t is known in the given information. b =5.145, substitute it into the equation Therefore, the newly calculated travertine deposition rate is V2 (V2=0.16cm / a), and the deposition ages of each layer are shown in Table 2.

[0082] Table 2. Huanglong travertine sediment samples before and after correction 210 Pb ex Annual results

[0083] As can be seen from Example 1, the application of plutonium isotope time-statistics in dating travertine deposits on a near-century timescale is feasible. This invention provides a method for correcting near-century timescale travertine deposits using plutonium isotopes. 210 Pb ex The method of determining the year is feasible.

[0084] Although the present invention has been described above in conjunction with exemplary embodiments and accompanying drawings, those skilled in the art should understand that various modifications can be made to the above embodiments without departing from the spirit and scope of the claims.

Claims

1. A method for correcting nearly 100-year-scale travertine deposits using plutonium isotopes. 210 Pb ex The method for determining the year is characterized by, The method includes: 1) Perform stratified sampling of sediment cores and record the deposition depth x of each vertical layer sample; 2) After pretreatment, samples from each layer are tested to obtain test data. Based on the test data, the parameters of each layer sample are calculated. 210 Pb ex Specific activity; 3) Samples from each layer were digested, separated, purified, and then tested. 239 Pu、 240 Calculate the number of Pu atoms in each layer of the sample. 239, 240 Pu specific activity, observed at different strata 239, 240 Pu specific activity, find the travertine deposition depth x1 corresponding to the maximum peak value; 4) Drawing 210 Pb ex From the nonlinear fitting curve of the exponential decay function between specific activity and sedimentation depth, the dating equation y of the nonlinear fitting curve of the exponential decay function is obtained. A Through the dating equation y A Calculate the deposition rate V1 and the deposition depth h1 for the target year; 5) Compare whether h1 and x1 are consistent. If h1 ≠ x1, then modify the year equation y. A Perform correction; 6) Tested based on samples at surface deposition depth x0 210 Pb ex Specific activity value y0, through 210 The decay equation of Pb over time, A （x） Calculate the target year 239, 240 Theoretical Pu peak layer depth x1 210 Pb ex Specific activity value y1; 7) Based on the obtained x0, y0, x1, and y1, apply the year-determining equation y A By applying constraints, a new dating equation y is obtained. B ; 8) Through the year-determining equation y B Calculate the corrected deposition rate V2 and the corresponding deposition age for each layer.

2. A method for correcting nearly 100-year-scale travertine deposits using plutonium isotopes as described in claim 1. 210 Pb ex The method for determining the year is characterized by, Step 1) describes stratified sampling of the sediment column, specifically as follows: Select the same travertine sediment column and perform stratified sampling, collecting travertine sediment samples from different depths for use in [the process]. 210 Pb, 239, 240 Pu experimental analysis and testing.

3. A method for correcting nearly 100-year-scale travertine deposits using plutonium isotopes as described in claim 1. 210 Pb ex The method for determining the year is characterized by, The pretreatment described in step 2) includes freeze drying, grinding, and homogenization; The experimental tests were conducted, and the test data obtained included experimental measurements using a well-type high-purity germanium gamma-ray spectrometer to obtain energy spectra at each layer, and recording the energy spectrum at each layer. 210 Pb (46.5 keV), 214 Pb (351.9 keV) 214 The counting peak of Bi (609.3 keV), the peak area after deducting the background (net count), the real-time measurement time of the sample, the detector efficiency curve (absolute detection efficiency at the 46.5 keV energy point), the self-absorption correction factor and the geometric correction factor, and the sample mass.

4. A method for correcting nearly 100-year-scale travertine deposits using plutonium isotopes, as described in claim 3. 210 Pb ex The method for determining the year is characterized by, Step 2) describes calculating the samples at each layer based on the test data. 210 Pb ex Specific activity includes: Through formula Calculate the total number of samples from each layer. 210 Pb activity, where A tot For the total 210 Pb activity, R is net count rate, ε is detector efficiency, P γ f is the emission probability of γ-rays at 46.5 keV. SA f is the self-absorption correction factor. geom It is a geometric correction factor; Through formula Calculate the total number of samples from each layer. 210 Pb specific activity, where C tot For the total 210 Pb specific activity, where m is the sample mass; pass Calculate the excess samples for each layer 210 Pb specific activity, where C ex (x) represents the excess at a deposition depth of x. 210 Pb specific activity, C tot (x) represents the total sediment at depth x. 210 Pb specific activity, C sup (x) represents the supported state at a deposition depth x. 210 Pb specific activity; Among them, obtained through testing 214 Pb, 214 The gamma peak of Bi can be used to infer... 226 Ra, under radioactive equilibrium conditions, supported state 210 Pb specific activity C sup equal 226 Ra activity.

5. A method for correcting nearly 100-year-scale travertine deposits using plutonium isotopes as described in claim 1. 210 Pb ex The method for determining the year is characterized by, The test described in step 3) 239 Pu、 240 The atomic number of Pu was determined using high-resolution inductively coupled plasma mass spectrometry. The calculation of samples at each layer 239, 240 Pu specific activity includes: Through formula Calculate the position of each layer 239, 240 Pu activity, where A x At a deposition depth x 239, 240 Pu activity, λ x The decay constant of plutonium isotopes (λ) 239 =9.1×10 -6 a -1 ;λ 240 =1.06×10 -4 a -1 ), N x The number of plutonium isotopes at a deposition depth x; Through formula Calculate the samples of each layer 239, 240 Pu specific activity, where C x At a deposition depth x 239, 240 Pu specific activity, A x At a deposition depth x 239, 240 Pu activity, where m is the sample mass; The maximum peak value corresponds to the travertine deposition depth x1, which represents 1963. 239, 240 The deposition depth x1 corresponding to the Pu feature timescale.

6. A method for correcting nearly 100-year-scale travertine deposits using plutonium isotopes as described in claim 1. 210 Pb ex The method for determining the year is characterized by, The drawing described in step 4) 210 Pb ex The nonlinear fitting curve of the exponential decay function between specific activity and deposition depth is plotted with the deposition depth of travertine as the x-axis and y-axis as the nonlinear fitting curve. 210 Pb ex Specific activity is represented by the ordinate y, and the specific activity of each travertine layer sample is... 210 Pb ex Plot the specific activity and sedimentation depth data points onto a coordinate system and draw a graph. 210 Pb ex Nonlinear fitting curve of exponential decay function between specific activity and deposition depth.

7. A method for correcting nearly 100-year-scale travertine deposits using plutonium isotopes as described in claim 1. 210 Pb ex The method for determining the year is characterized by, The dating equation y described in step 4) A for , where y A For the deposition depth x 210 Pb ex Specific activity, in dpm / g; x is the depositional depth calculated from the surface of the travertine deposit, in cm; A a For the surface layer of sediments 210 Pb ex Specific activity, expressed in dpm / g; t a The attenuation characteristic depth parameter, in physical terms, is the "characteristic scale" of the attenuation of nuclide activity in sediments with depth; y a As the background 210 Pb ex Specific activity, expressed in dpm / g.

8. A method for correcting nearly 100-year-scale travertine deposits using plutonium isotopes as described in claim 1. 210 Pb ex The method for determining the year is characterized by, Step 6) 210 decay equation of Pb over time , where A （x） At the deposition depth x layer 210 Pb ex Specific activity, in dpm / g; A0 is the measured value at the surface layer. 210 Pb ex Specific activity (A0=y0), in dpm / g; Δt is the depositional age between the sampling time and 1963, in years; the target year for calculation is 1963. 239, 240 Theoretical Pu peak layer depth x1 210 Pb ex Specific activity value .

9. A method for correcting nearly 100-year-scale travertine deposits using plutonium isotopes as described in claim 1. 210 Pb ex The method for determining the year is characterized by, Step 7) describes applying the obtained x0, y0, x1, and y1 to the year-determining equation y. A The constraint is applied to force the fitted curve to pass through the measured point (x0, y0) of the travertine surface sediments and the corresponding theoretical point (x1, y1) in 1963; the new dating equation .

10. A method for correcting nearly 100-year-scale travertine deposits using plutonium isotopes, as described in claim 9. 210 Pb ex The method for determining the year is characterized by, Step 8) describes using the year-determining equation y B The corrected deposition rate V2 and the corresponding deposition age for each layer are calculated using the dating equation. Given data t b Substitute it into the equation The corrected deposition rate V2 is calculated; the corrected deposition age t for each layer is calculated by t=x / V2, where t is the corrected deposition age for each layer, x is the deposition depth, and V2 is the corrected deposition rate.

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