Method for extracting sedimentary water body salinity information from sediment

Abstract

The invention relates to a method for extracting sedimentary water salinity information from sediments, and belongs to the technical field of environmental analysis. The [B] AC / [Ba] HAc obtained by dividing the content of boron adsorbed on the surface of the sediment leached by neutral ammonium carbonate (AC) by the content of barium adsorbed on the surface of the sediment leached by acetic acid (HAc) is specifically and selectively extracted by combining ammonium carbonate and acetic acid leaching; and reconstructing the practical salinity of the sedimentary water body according to an empirical formula obtained by using the pore water with known salinity and the content of adsorbed B and Ba eluted from the surface of the sediment balanced with the pore water. According to the method, the research object range of sedimentary environment reconstruction / recovery is greatly widened. Compared with a traditional total rock extraction method and an acetic acid / acetate buffer solution method, the method has the advantages that adverse effects of dissolution of carbonate and barite in the sediment on data are reduced to the maximum extent, and extracted sediment water salinity information is more accurate.

Description

Technical Field

[0001] This invention relates to a method for extracting salinity information of sedimentary water from sediments, belonging to the field of environmental analysis technology, and is particularly applicable to silicate sediments or sedimentary rocks with high barite and carbonate content. Background Technology

[0002] Reconstructing salinity information of sedimentary water bodies through elemental composition is an important tool for paleoenvironmental research. Existing methods include: 1) whole-rock B / Ga and Sr / Ba ratios; 2) extracting exchangeable strontium / barium ratios from sediment surfaces using acetic acid, ammonium acetate, or sodium acetate. However, traditional methods using acetic acid, ammonium acetate, or sodium acetate to extract exchangeable elements from sediment surfaces easily dissolve carbonates and barite in the sediments, thus affecting the accuracy of the obtained data and making it impossible to quantitatively reconstruct the salinity of the sedimentary environment.

[0003] The boron (B) and barium (Ba) content of sediments is influenced by their mineral composition. Only by accurately extracting boron and barium adsorbed on the surface of silicate sediments can salinity information of the sedimentary water be obtained. Dissolving the entire rock or leaching sediments with acetic acid (HAc) or acetic acid-ammonium acetate (AA) buffer solutions will lead to carbonate dissolution, resulting in higher B levels. Using ammonium or sodium salts, such as ammonium acetate (AA), sodium acetate (NaAc), or ammonium carbonate (AC), for leaching will lead to barite dissolution, resulting in higher Ba levels. Quantitatively reconstructing the salinity of sedimentary water requires maximizing the extraction of B and Ba adsorbed on the sediment surface while avoiding the influence of different minerals in the sediment on B and Ba concentrations.

[0004] Therefore, it is essential to develop a more accurate and efficient method for extracting salinity information of sedimentary water from sediments. Summary of the Invention

[0005] In view of the above analysis, the embodiments of the present invention aim to provide a method for extracting salinity information of sedimentary water from sediments, in order to solve one or more of the problems existing in the prior art. Using the present invention, it is possible to reconstruct water salinity indicators in paleoenvironments more accurately and efficiently.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A method for extracting sedimentary environment salinity information from sedimentary rock geological samples includes the following steps: Step (1): Extract adsorbed boron from the sediment using ammonium carbonate; (1.1) Add 10-30 mg of sediment to a 15 mL centrifuge tube A; (1.2) Add 4~6 mL of 0.5~1 M ammonium carbonate to the sediment, vortex at 500~2800 rpm for 15~30 minutes, place in an ultrasonic cleaner and sonicate for 15 minutes, vortex again at 500~2500 rpm for 15~30 minutes, and centrifuge at 3000~4000 rpm. (1.3) Clean the plastic syringe and filter head (0.22um) with 2% nitric acid; (1.4) Pour the supernatant into a clean syringe fitted with a filter head, and filter the supernatant into a 15mL centrifuge tube B; (1.5) Repeat steps (1.2) to (1.4) to ensure complete extraction of boron by two extractions, and obtain 8 to 12 mL of ammonium carbonate eluent; (1.6) Add concentrated nitric acid with a concentration of 15~16M to the ammonium carbonate solution to prepare a mixed solution of ammonium carbonate and 2% nitric acid; (1.7) Add a certain amount of boron to a mixed solution of ammonium carbonate and 2% nitric acid of the same concentration to prepare elemental standard solutions with concentrations of 0, 5, 10, 20 and 50 μg / L for instrument calibration. Test the B content in the mixed solution of ammonium carbonate and 2% nitric acid on ICP-MS. Calculate the concentration of boron leached per g of sample using the weight of the sediment and the volume of the eluent. Obtain [B]AC according to the formula [B]ACμg / g=Eluent B concentration (μg / mL)×Eluent volume (mL) / Sediment weight (g).

[0007] Step (2): Extract adsorbed barium from the sediment using acetic acid; (2.1) Add 10-30 mg of sediment to a 15 mL centrifuge tube C and record the weight; (2.2) Add 6~10mL of 0.2~0.5M acetic acid to the sediment, mix the sediment and acetic acid solution, release the gas, and then seal the test tube tightly. Vortex at 500~2800rpm for 15~30 minutes, place it in an ultrasonic cleaner for ultrasonic treatment for 15 minutes, vortex at 500~2500rpm for 15~30 minutes again, and then centrifuge at 3000~4000rpm. (2.3) Pour the supernatant into a clean syringe equipped with a filter head, filter the supernatant into a 15mL centrifuge tube D, and obtain acetic acid rinsing solution; (2.4) Add concentrated nitric acid with a concentration of 15~16M to the acetic acid rinsing solution to prepare a mixed solution of acetic acid and 2% nitric acid; (2.5) Add a quantitative amount of barium to a mixed solution of acetic acid and 2% nitric acid of the same concentration to prepare elemental standard solutions with concentrations of 0, 5, 10, 20, and 50 μg / L for instrument calibration. Test the Ba content in the mixed solution of acetic acid and 2% nitric acid obtained in step (2.4) on an ICP-MS. Calculate the concentration of barium leached per g of sample using the weight of the sediment and the volume of the eluent. Obtain [Ba]HAc μg / g according to the formula [Ba]HAc = eluent Ba concentration (μg / mL) × eluent volume (mL) / sediment weight (g). Step (3): Calculate the [B]AC / [Ba]HAc ratio of the sediments, and determine the practical salinity of the sedimentary environment and sedimentary water body based on the [B]AC / [Ba]HAc ratio. Based on sediment samples (~100 samples) collected from known sedimentary environments, measure their [B]AC / [Ba]HAc ratios using the method of this application. Based on the sedimentary environments corresponding to these data, define the following rules: [B]AC / [Ba]HAc less than or equal to 0.03 indicates a freshwater sedimentary environment (<1 psu), between 0.03 and 1.7 indicates a marine-continental transitional sedimentary environment (1~31 psu) or brackish water, and [B]AC / [Ba]HAc greater than or equal to 1.7 indicates a marine sedimentary environment. In a marine environment, the practical salinity of the sedimentary water body can be calculated using the following formula: Practical salinity = ([B]AC / [Ba]HAc + 7.27) / 0.28, in psu. When [B]AC / [Ba]HAc is 1.7, the practical salinity calculated using this formula is 32 psu, which conforms to the definition of seawater (32~38 psu). Theoretically, these thresholds may fluctuate as the amount of data increases, with fluvial facies possibly slightly less than 0.03 and marine facies possibly slightly less than 1.7.

[0008] The method described in this application uses neutral and weakly acidic reagents to selectively extract B and Ba adsorbed on the surface of silicate sediments at room temperature. Then, based on the practical salinity discrimination formula obtained from sediment samples with known practical salinity of the sedimentary water body, the depositional environment information and the practical salinity of the sedimentary water body are quickly obtained. The specific steps are as follows: 1) The sediment is repeatedly leached with neutral ammonium carbonate solution to extract the boron adsorbed on its surface; 2) The sediment is leached with dilute acetic acid to extract the barium adsorbed on its surface; 3) The boron and barium concentrations of the leaching solution are tested by inductively coupled plasma mass spectrometry and the [B]AC / [Ba]HAc ratio is calculated; 4) Since the pore water filling the sediment voids represents the overlying water body at the time of deposition, its practical salinity is close to the practical salinity of the sediment water body. Therefore, the practical salinity of the pore water in the same layer of sediment can be fitted with the [B]AC / [Ba]HAc ratio extracted by this patented method to obtain the practical salinity discrimination formula for the marine sedimentary environment: Practical salinity (psu) = ([B]AC / [Ba]HAc + a) / b. According to the practical salinity of the sediment core of International Ocean Drilling Program (IODP) U1464B and its corresponding pore water, the value of a is 7.27 and the value of b is 0.28. When [B]AC / [Ba]HAc≤0.03, the sedimentary water is freshwater (<1 psu); between 0.03 and 1.7 indicates a marine-continental transitional facies (1~31 psu); greater than or equal to 1.7 indicates a marine sedimentary environment, and the practical salinity of the sedimentary water can be calculated using this formula in marine sedimentary environments.

[0009] The principle of this method is based on the fact that the ability of clay surfaces to adsorb boron (B) increases significantly with increasing salinity of the sedimentary water, while the ability to adsorb barium (Ba) decreases significantly with increasing salinity. Traditional methods for extracting exchangeable elements from sediment surfaces using acetic acid, ammonium acetate, or sodium acetate easily dissolve carbonates and barite in the sediments, affecting the accuracy of the obtained data and making it impossible to quantitatively reconstruct the salinity of the sedimentary environment. Carbonates contain trace amounts of boron (10–100 μg / g). In comparison, strontium is an order of magnitude higher in carbonates than boron (~1000 μg / g), and Ba is the main element in barite (BaSO4). Therefore, the B / Ba ratio can be used more effectively to reconstruct the salinity of the sedimentary environment, with a much higher accuracy than the Sr / Ba, B / Ga, and S / TOC ratios extracted using traditional methods. Firstly, the Sr / Ba ratio is more affected by the dissolution of carbonates and barite than the B / Ba ratio. Whole-rock B / Ga ratios are also a method for quantitatively reconstructing sedimentary salinity based on the boron content adsorbed on the clay surface; however, the B and Ga content of the rock itself can affect data accuracy. Traditional single leaching may also fail to completely extract exchangeable boron because the initial leaching solution itself has a high salinity, which slows down boron desorption.

[0010] This application utilizes the property of ammonium carbonate to slow down carbonate dissolution. A neutral ammonium carbonate solution is used to elute boron (B) adsorbed on the sediment surface. Based on the characteristic that boron adsorption capacity on clay surfaces decreases with decreasing water salinity, a second leaching is performed on the sediment sample to completely extract exchangeable boron adsorbed on the sediment surface. The method of this application utilizes the property that barium adsorbed on the sediment surface desorbs under acidic conditions and the property that barite has very low solubility in dilute acetic acid to extract barium (Ba) adsorbed on the sediment surface using dilute acetic acid. The B and Ba contents in these two sets of leaching solutions are accurately measured using ICP-MS, and the [B]AC / [Ba]HAc ratio is quantitatively calculated. Finally, the reconstructed practical salinity of the sedimentary water body is obtained by comparing the [B]AC / [Ba]HAc ratio of the sediment with the known practical salinity of the water body.

[0011] This application utilizes the property of ammonium carbonate to extract adsorbed boron and barium from sediments while minimizing carbonate dissolution, thereby extracting boron adsorbed on the sediment surface using ammonium carbonate. Furthermore, based on the characteristic that boron adsorption capacity on clay surfaces decreases with decreasing water salinity, this application performs a second leaching of the sediment sample to completely extract exchangeable boron adsorbed on the sediment surface. Secondly, this application utilizes the low solubility of barite in dilute acetic acid to extract barium (Ba) adsorbed on the sediment surface using dilute acetic acid. The B and Ba contents in these two leaching solutions are accurately measured using ICP-MS, and the [B]AC / [Ba]HAc ratio is calculated. A ratio of [B]AC / [Ba]HAc less than or equal to 0.03 indicates a freshwater sedimentary environment (<1 psu); a ratio between 0.03 and 1.7 indicates a marine-continental transitional sedimentary environment (1~31 psu) or brackish water; and a ratio of [B]AC / [Ba]HAc greater than or equal to 1.7 indicates a marine sedimentary environment. In marine sedimentary environments, the practical salinity of the sedimentary water is calculated according to the following formula: Practical salinity = ([B]AC / [Ba]HAc + 7.27) / 0.28, in psu.

[0012] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects: (1) Existing salinity indicators are inefficient, requiring 1 to 2 weeks to digest a batch of samples. This application can complete the preparation and testing of a batch of samples in 4 to 5 hours; and it can avoid strong acids and high temperatures, requiring only test tubes, shaking and filtering devices, and can be completed on automated equipment, making it suitable for Mars exploration or exploration in uninhabited areas.

[0013] (2) Existing whole-rock Sr / Ba and B / Ga salinity indices, as well as acetic acid-ammonium acetate-sodium acetate partial extraction methods, are all affected by carbonates and barite in sediments / sedimentary rocks. The method proposed in this application can minimize the influence of the sediment's own composition and achieve the effect of quantitatively reconstructing the salinity of the sedimentary environment.

[0014] (3) Existing whole-rock Sr / Ba and B / Ga testing methods require the use of hazardous chemicals such as hydrofluoric acid or strong alkalis to digest silicate samples at high temperatures in order to obtain accurate B, Sr, and Ba contents. This application avoids the use of hydrofluoric acid or strong alkalis and high-temperature conditions, and can safely and effectively extract salinity information of the sedimentary environment by using very diluted acetic acid (acetic acid concentration of 0.2~0.5M, which is lower than 5%~50% or 0.8~8.5M of existing methods).

[0015] (4) Existing single leaching indicators cannot simultaneously avoid the dissolution of carbonates and barite, thus leading to bias. This method employs targeted selective extraction by combining ammonium carbonate and acetic acid leaching. Boron adsorbed on the sediment surface is leached multiple times with neutral ammonium carbonate (AC), and the content of barium adsorbed on the sediment surface is obtained by leaching with acetic acid. Furthermore, the [B]AC / [Ba]HAc ratio and empirical formulas for practical salinity of water bodies are obtained from pore water and sediments with known salinity, thereby obtaining more accurate salinity information of sediment water bodies.

[0016] (5) This application is applicable to sediment samples with high carbonate and barite content, greatly expanding the scope of research objects for sedimentary environment reconstruction / restoration. Compared with traditional whole-rock extraction methods and acetic acid / acetate buffer solution methods, this method minimizes the adverse effects of the dissolution of carbonates and barite in sediments on the data. Secondly, by reducing the solid-liquid ratio (traditional methods generally use a relatively high solid-liquid ratio of 1:500, this application uses 10~30mg of solid sediment or powdered sedimentary rock with 8~12mL of AC solution to achieve a solid-liquid ratio of 1:1200), combined with multiple rinsing and high-speed vortex oscillation, the complete extraction of adsorbed elements is ensured. For sediments that have not formed rocks, pulverization is not required; for sediments that have formed rocks, pulverization to 300 mesh is required. This application uses syringe filtration to avoid the adverse effects of small sediment particles on the solution and instrument testing. It also avoids the use of reagents with excessively high cation concentrations (such as sodium acetate), thereby ensuring the accuracy of experimental data.

[0017] In this invention, the above-described technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of this invention will be set forth in the following description, and some advantages may become apparent from the description or be learned by practicing the invention. The objects and other advantages of this invention can be realized and obtained from what is particularly pointed out in the description and drawings. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments or prior art of this specification, the drawings used in the description of the embodiments or prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the embodiments of this specification. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings. Figure 1 A flowchart illustrating the method for extracting sedimentary environment salinity information from sedimentary rock geological samples provided by the present invention. Figure 2 The graph shows the correlation between the [B]AC / [Ba]HAc ratio extracted in Example 1 and the salinity of pore water in the same layer. Figure 3 This is a graph showing the correlation between the [B]HAc / [Ba]HAc ratio extracted by conventional acetic acid rinsing in Example 1 and the salinity of pore water in the same layer. Figure 4 This is a graph showing the relationship between the boron content obtained from the stepwise rinsing in Example 4. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments, and the embodiments do not constitute a limitation on the embodiments of this application. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0020] Example 1 Figure 1 A flowchart illustrating the method for extracting sedimentary environment salinity information from sedimentary rock geological samples is shown.

[0021] Since the pore water filling the voids in sediments represents the overlying water body at the time of deposition, its practical salinity is close to that of the sedimentary water body. Therefore, by fitting the practical salinity of the pore water in the same sediment layer with the [B]AC / [Ba]HAc ratio extracted using the method of this application, a correlation diagram between the extracted [B]AC / [Ba]HAc ratio and the salinity of the pore water in the same layer is obtained, as shown in the figure. Figure 2As shown, the practical salinity discrimination formula for marine sedimentary environments is obtained: Practical salinity = ([B]AC / [Ba]HAc + a) / b. According to the practical salinity of the sediment core of International Ocean Drilling Program (IODP) U1464B and its corresponding pore water, the value of a is 7.27 and the value of b is 0.28. When [B]AC / [Ba]HAc ≤ 0.03, it indicates a freshwater sedimentary environment (<1 psu); between 0.03 and 1.7, it indicates a marine-continental transitional sedimentary environment (1~31 psu) or brackish water; and [B]AC / [Ba]HAc greater than or equal to 1.7 indicates a marine sedimentary environment. When in a marine sedimentary environment, the practical salinity of the sedimentary water can be calculated using this formula.

[0022] like Figure 3 As shown, the linear relationship between the B / Ba ratio obtained by traditional acetic acid rinsing and the practical salinity of pore water is poor. Therefore, the practical salinity discrimination formula obtained by the method of this application is more accurate.

[0023] Example 2 This embodiment uses sediment samples from the Yangtze River, Qiantang River, and East China Sea.

[0024] Weigh 30 mg of sediment samples from the Yangtze River, Qiantang River, and East China Sea using the method described in this application, following these steps: Step (1): Extract adsorbed boron from the sediment using ammonium carbonate; (1.1) Add 30 mg of sediment to a 15 mL centrifuge tube A; (1.2) Add 6 mL of 0.5 M ammonium carbonate to the sediment, vortex at 1500 rpm for 20 minutes, place in an ultrasonic cleaner for ultrasonic treatment for 15 minutes, vortex at 1500 rpm for 20 minutes, and centrifuge at 3500 rpm. (1.3) Clean the plastic syringe and filter head with 2% nitric acid (water system, 0.22um); (1.4) Pour the supernatant into a clean syringe fitted with a filter head, and filter the supernatant into a 15mL centrifuge tube B; (1.5) Repeat steps (1.2) to (1.4) to ensure complete extraction of boron by two extractions to obtain 10 mL of ammonium carbonate eluent; (1.6) Add concentrated nitric acid with a concentration of 15~16M to the ammonium carbonate solution to prepare a mixed solution of ammonium carbonate and 2% nitric acid; (1.7) Add a certain amount of boron to a mixed solution of ammonium carbonate and 2% nitric acid of the same concentration to prepare elemental standard solutions with concentrations of 0, 5, 10, 20 and 50 μg / L for instrument calibration. Test the B content in the mixed solution of ammonium carbonate and 2% nitric acid on ICP-MS. Calculate the concentration leached per g of sample using the weight of the sediment and the volume of the eluent. Obtain [B]AC according to the formula [B]ACμg / g=Eluent B concentration (μg / mL)×Eluent volume (mL) / Sediment weight (g).

[0025] Step (2): Extract adsorbed barium from the sediment using acetic acid; (2.1) Add 30 mg of sediment to a 15 mL centrifuge tube C and record the weight; (2.2) Add 10 mL of 0.5 M acetic acid to the sediment, mix the sediment and acetic acid solution, release the gas, and then seal the test tube tightly. Vortex at 1800 rpm for 20 minutes, place it in an ultrasonic cleaner for ultrasonic treatment for 15 minutes, vortex at 500~2500 rpm for 15~30 minutes, and then centrifuge at 3500 rpm. (2.3) Pour the supernatant into a clean syringe equipped with a filter head, filter the supernatant into a 15mL centrifuge tube D, and obtain acetic acid rinsing solution; (2.4) Add concentrated nitric acid with a concentration of 15~16M to the acetic acid rinsing solution to prepare a 2% nitric acid and acetic acid mixed solution; (2.5) Add a quantitative amount of barium to a mixed solution of acetic acid and 2% nitric acid of the same concentration to prepare elemental standard solutions with concentrations of 0, 5, 10, 20, and 50 μg / L for instrument calibration. Test the Ba content in the mixed solution of acetic acid and 2% nitric acid obtained in step (2.4) on an ICP-MS. Calculate the concentration leached per g of sample using the weight of the sediment and the volume of the eluent. Obtain [Ba]HAc μg / g according to the formula [Ba]HAc = eluent Ba concentration (μg / mL) × eluent volume (mL) / sediment weight (g). (2.6) Add a quantitative amount of boron to a mixed solution of acetic acid and 2% nitric acid of the same concentration to prepare elemental standard solutions with concentrations of 0, 5, 10, 20, and 50 μg / L for instrument calibration. Test the B content in the mixed solution of acetic acid and 2% nitric acid obtained in step (2.4) on an ICP-MS. Calculate the concentration leached per g of sample using the weight of the sediment and the volume of the eluent. According to the formula [B]HAcμg / g = eluent B concentration (μg / mL) × eluent volume (mL) / sediment weight (g), obtain [B]HAc. Step (3): Calculate the [B]AC / [Ba]HAc ratio. The ratios of the sediments from the Qiantang River and the Yangtze River are much less than 0.03, indicating a freshwater sedimentary environment, and the difference from marine sediments is much greater than the Sr / Ba related index. According to the practical salinity formula of this application, the practical salinity of the East China Sea is calculated as ([B]AC / [Ba]HAc + 7.27) / 0.28 = 32.14 psu, which is consistent with the practical salinity characteristics of the seawater here. The test results are shown in Table 1.

[0026] Traditional whole-rock Sr / Ba ratio thresholds are <0.2 for freshwater, 0.2–0.5 for marine-continental transitional facies, and >0.5 for seawater. However, marine sediments extracted using this traditional method have a ratio far less than 0.5 due to excessive barite, indicating a marine-continental transitional facies, close to freshwater. Conversely, Yangtze River sediments, due to excessive carbonate, have a ratio greater than 0.2, incorrectly indicating a marine-continental transitional environment, not river water. The [Sr]HAc / [Ba]HAc ratio of Yangtze River sediments extracted using traditional acetic acid is greater than 1, incorrectly identifying a marine sedimentary environment. The whole-rock B / Ga ratio of East China Sea sediments is 3.302 + / - 0.07, far less than the marine threshold of 6, incorrectly indicating a marine-continental transitional facies.

[0027] like Figure 3 As shown, the linear relationship between the [B]HAc / [Ba]HAc ratio obtained by traditional acetic acid rinsing and the practical salinity of pore water is poor. Therefore, the practical salinity discrimination formula obtained by the method of this application is more accurate.

[0028] Table 1 Example 3 This embodiment uses a sample numbered D113 (depth 2.9 meters) of sediment from the Qiantang River estuary, which is rich in calcium carbonate.

[0029] 10 mg of a calcium carbonate-rich sediment sample, designated D113 (depth 2.9 m), from the Qiantang River estuary was weighed using the method described in this application, following these steps: Includes the following steps: Step (1): Extract adsorbed boron from the sediment using ammonium carbonate; (1.1) Add 10 mg of sediment to a 15 mL centrifuge tube A; (1.2) Add 4 mL of 1M ammonium carbonate to the sediment, vortex at 500 rpm for 15 minutes, place it in an ultrasonic cleaner for ultrasonic treatment for 15 minutes, vortex at 500 rpm for 15 minutes, and centrifuge at 3000 rpm. (1.3) Clean the plastic syringe and filter head with 2% nitric acid (water system, 0.22um); (1.4) Pour the supernatant into a clean syringe fitted with a filter head, and filter the supernatant into a 15mL centrifuge tube B; (1.5) Repeat steps (1.2) to (1.4) to ensure complete extraction of boron by two extractions, and obtain 8 to 12 mL of ammonium carbonate eluent; (1.6) Add concentrated nitric acid with a concentration of 15~16M to the ammonium carbonate solution to prepare a mixed solution of ammonium carbonate and 2% nitric acid; (1.7) Add a certain amount of boron to a mixed solution of ammonium carbonate and 2% nitric acid of the same concentration to prepare elemental standard solutions with concentrations of 0, 5, 10, 20 and 50 μg / L for instrument calibration. Test the B content in the mixed solution of ammonium carbonate and 2% nitric acid on ICP-MS. Calculate the concentration leached per g of sample using the weight of the sediment and the volume of the eluent. Obtain [B]AC according to the formula [B]ACμg / g=Eluent B concentration (μg / mL)×Eluent volume (mL) / Sediment weight (g).

[0030] Step (2): Extract adsorbed barium from the sediment using acetic acid; (2.1) Add 10 mg of sediment to a 15 mL centrifuge tube C and record the weight; (2.2) Add 6 mL of 0.2 M acetic acid to the sediment, mix the sediment and acetic acid solution, release the gas, and then seal the test tube tightly. Vortex at 500 rpm for 15 minutes, place it in an ultrasonic cleaner and sonicate for 15 minutes. Vortex again at 500~2500 rpm for 15~30 minutes, and then centrifuge at 3000 rpm. (2.3) Pour the supernatant into a clean syringe equipped with a filter head, filter the supernatant into a 15mL centrifuge tube D, and obtain acetic acid rinsing solution; (2.4) Add concentrated nitric acid with a concentration of 15~16M to the acetic acid rinsing solution to prepare a mixed solution of acetic acid and 2% nitric acid; (2.5) Add a quantitative amount of barium to a mixed solution of acetic acid and 2% nitric acid of the same concentration to prepare elemental standard solutions with concentrations of 0, 5, 10, 20, and 50 μg / L for instrument calibration. Test the Ba content in the mixed solution of acetic acid and 2% nitric acid obtained in step (2.4) on an ICP-MS. Calculate the concentration leached per g of sample using the weight of the sediment and the volume of the eluent. Obtain [Ba]HAc μg / g according to the formula [Ba]HAc = eluent Ba concentration (μg / mL) × eluent volume (mL) / sediment weight (g). Step (3): The [B]AC / [Ba]HAc ratio of the sediment was calculated to be 0.034, indicating a marine-continental sedimentary environment, which is consistent with the sedimentary environment of the sample. The test results are shown in Table 2.

[0031] Traditional whole-rock Sr / Ba ratio thresholds are <0.2 for freshwater, 0.2–0.5 for marine-continental transitional facies, and >0.5 for seawater. This sample has a whole-rock Sr / Ba ratio of 0.57, incorrectly identifying it as a marine sedimentary environment. Its acetic acid-extracted Sr / Ba ratio is 2.45, correctly indicating a marine-continental transitional environment; the ammonium acetate-extracted Sr / Ba ratio is 2.5, incorrectly indicating a marine environment. The sample's whole-rock B / Ga ratio is 3.38, correctly indicating a marine-continental transitional / marine-continental transitional environment.

[0032] Table 2 Example 4 Weigh 100 mg of deep-sea sediment sample and mix it with 1 M ammonium carbonate solution. Take the supernatant and analyze it using ICP-MS. The boron content was obtained by stepwise elution as shown in the figure. Figure 4 As shown, multiple rinsing can more effectively extract adsorbed boron from sediments.

[0033] Example 5: Multiple rinses are superior to a single rinse 30 mg of Qiantang River sediment sample (sample number D113) was mixed with 4 mL of 1 M ammonium carbonate solution and eluted three times using the method described in this application. The supernatant was analyzed by ICP-MS, and the results are shown in Table 3. This example demonstrates that multiple elutions can more effectively extract adsorbed boron from sediments.

[0034] Table 3 Example 5 The sample used in this embodiment was prepared by mixing clay with seawater with a salinity of 32.69 psu by shaking for 30 days, centrifuging to remove the supernatant, freeze-drying, and weighing 20 mg. The following steps were followed: Step (1): Extract adsorbed boron from the sediment using ammonium carbonate; (1.1) Add 20 mg of sediment to a 15 mL centrifuge tube A; (1.2) Add 5 mL of 1M ammonium carbonate to the sediment, vortex at 2800 rpm for 30 minutes, place it in an ultrasonic cleaner for ultrasonic treatment for 15 minutes, vortex at 2500 rpm for 30 minutes, and centrifuge at 4000 rpm. (1.3) Clean the plastic syringe and filter head with 2% nitric acid (water system, 0.22um); (1.4) Pour the supernatant into a clean syringe fitted with a filter head, and filter the supernatant into a 15mL centrifuge tube B; (1.5) Repeat steps (1.2) to (1.4) to ensure complete extraction of boron by two extractions, and obtain 8 to 12 mL of ammonium carbonate eluent; (1.6) Add concentrated nitric acid with a concentration of 15~16M to the ammonium carbonate solution to prepare a mixed solution of ammonium carbonate and 2% nitric acid; (1.7) Add a certain amount of boron to a mixed solution of ammonium carbonate and 2% nitric acid of the same concentration to prepare elemental standard solutions with concentrations of 0, 5, 10, 20 and 50 μg / L for instrument calibration. Test the B content in the mixed solution of ammonium carbonate and 2% nitric acid on ICP-MS. Calculate the concentration leached per g of sample using the weight of the sediment and the volume of the eluent. Obtain [B]AC according to the formula [B]ACμg / g=Eluent B concentration (μg / mL)×Eluent volume (mL) / Sediment weight (g).

[0035] Step (2): Extract adsorbed barium from the sediment using acetic acid; (2.1) Add 20 mg of sediment to a 15 mL centrifuge tube C and record the weight; (2.2) Add 10 mL of 0.3 M acetic acid to the sediment, mix the sediment and acetic acid solution, release the gas, and then seal the test tube tightly. Vortex at 2800 rpm for 30 minutes, place it in an ultrasonic cleaner for ultrasonic treatment for 15 minutes, vortex at 2500 rpm for 15 minutes, and then centrifuge at 4000 rpm. (2.3) Pour the supernatant into a clean syringe equipped with a filter head, filter the supernatant into a 15mL centrifuge tube D, and obtain acetic acid rinsing solution; (2.4) Add concentrated nitric acid with a concentration of 15~16M to the acetic acid rinsing solution to prepare a mixed solution of acetic acid and 2% nitric acid; (2.5) Add a quantitative amount of barium to a mixed solution of acetic acid and 2% nitric acid of the same concentration to prepare elemental standard solutions with concentrations of 0, 5, 10, 20, and 50 μg / L for instrument calibration. Test the Ba content in the mixed solution of acetic acid and 2% nitric acid obtained in step (2.4) on an ICP-MS. Calculate the concentration leached per g of sample using the weight of the sediment and the volume of the eluent. Obtain [Ba]HAc according to the formula [Ba]HAc μg / g = eluent Ba concentration (μg / mL) × eluent volume (mL) / sediment weight (g). Step (3): Calculate the [B]AC / [Ba]HAc ratio. Based on [B]AC / [Ba]HAc, determine the depositional environment and the salinity of the depositional water. The [B]AC / [Ba]HAc ratio is 1.92 + / - 0.05, which is greater than or equal to 1.7, indicating a marine depositional environment. Calculate the practical salinity of the depositional water using the following formula: Practical salinity = ([B]AC / [Ba]HAc + 7.27) / 0.28, which is 32.82 + / - 0.18 psu. This result is consistent with the practical salinity of 32.69 psu used in the experiment, which is within the error range.

[0036] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of this application. It should be understood that the above description is only a specific embodiment of this application and is not intended to limit the scope of protection of this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A method for extracting salinity information of sedimentary water from sediments, characterized in that, The method includes the following steps: (1) Boron adsorbed on the surface of sediments was extracted using ammonium carbonate and the [B]AC content was determined. (2) Barium adsorbed on the surface of the sediment was extracted using acetic acid, and the content of [Ba]HAc was determined. (3) Calculate the [B]AC / [Ba]HAc ratio and determine the sedimentary environment based on the [B]AC / [Ba]HAc ratio; for sediments formed in marine environments, obtain the practical salinity of the sedimentary water body according to the practical salinity calculation formula.

2. The method as described in claim 1, characterized in that, In step (3), a B]AC / [Ba]HAc ratio less than or equal to 0.03 indicates a freshwater sedimentary environment, a ratio between 0.03 and 1.7 indicates a marine-continental transitional sedimentary environment or brackish water, and a B]AC / [Ba]HAc ratio greater than or equal to 1.7 indicates a marine sedimentary environment. The practical salinity calculation formula is as follows: Practical salinity = ([B]AC / [Ba]HAc + 7.27) / 0.28, with the unit being psu.

3. The method as described in claim 1, characterized in that, In step (1), the concentration of ammonium carbonate is 0.5~1M, and the mass-volume ratio of sediment to ammonium carbonate is (10~30)mg:(4~6)mL.

4. The method as described in claim 1, characterized in that, In step (1), the specific extraction operation is as follows: vortex oscillation at 500~2800rpm for 15~30min, place in an ultrasonic cleaner for ultrasonic treatment for 15min, then vortex oscillation at 500~2500rpm for 15~30min again, and centrifuge at 3000~4000rpm.

5. The method as described in claim 4, characterized in that, In step (1), after the extraction step, the following steps are also included: pouring the supernatant after centrifugation into a syringe equipped with a filter head and filtering the supernatant; repeating the extraction and filtration operations to obtain 8-12 mL of ammonium carbonate eluent; then adding concentrated nitric acid with a concentration of 15-16 M to the ammonium carbonate eluent to prepare a mixed solution of ammonium carbonate and 2% nitric acid.

6. The method as described in claim 5, characterized in that, In step (1), the step of determining the [B]AC content using ICP-MS includes: adding boron to a mixed solution of ammonium carbonate and 2% nitric acid of the same concentration, preparing elemental standard solutions with concentrations of 0, 5, 10, 20, and 50 μg / L to calibrate the instrument, testing the boron content in the mixed solution of ammonium carbonate and 2% nitric acid on the ICP-MS, calculating the boron concentration leached per g of sample using the weight of the sediment and the volume of the eluent, and obtaining [B]AC according to the formula [B]AC = eluent B concentration × eluent volume / sediment weight.

7. The method as described in claim 1, characterized in that, In step (2), the concentration of acetic acid is 0.2~0.5M, and the mass-to-volume ratio of sediment to acetic acid is (10~30) mg: (6~10) mL.

8. The method as described in claim 1, characterized in that, In step (2), the specific extraction operation is as follows: after mixing the sediment and acetic acid solution and releasing the gas, the test tube is tightly covered and vortexed at 500~2800rpm for 15~30min. The tube is then placed in an ultrasonic cleaner for ultrasonic treatment for 15min, vortexed again at 500~2500rpm for 15~30min, and then centrifuged at 3000~4000rpm.

9. The method as described in claim 8, characterized in that, In step (2), after the extraction step, the following steps are also included: pouring the supernatant after centrifugation into a syringe equipped with a filter head and filtering the supernatant; then adding concentrated nitric acid with a concentration of 15~16M to prepare a mixed solution of acetic acid and 2% nitric acid.

10. The method as described in claim 9, characterized in that, In step (2), the step of determining the [Ba]HAc content using ICP-MS includes: adding barium to a mixed solution of acetic acid and 2% nitric acid of the same concentration, preparing elemental standard solutions with concentrations of 0, 5, 10, 20, and 50 μg / L to calibrate the instrument, testing the barium content in the mixed solution of acetic acid and 2% nitric acid on the ICP-MS, calculating the concentration of barium leached per g of sample using the weight of the sediment and the volume of the eluent, and obtaining [Ba]HAc according to the formula [Ba]HAc = eluent Ba concentration × eluent volume / sediment weight.

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