CN-116818690-B - Turbidity compensation-based nitrate measurement method under high pressure

Abstract

The invention discloses a method for measuring nitrate under high pressure based on turbidity compensation, which comprises the following steps of respectively calculating standard seawater, turbidity and attenuation coefficient of nitrate based on a known absorbance model, synchronously monitoring turbidity under different measurement conditions based on multi-angle scattered light signals, establishing a turbidity calculation model by taking a light intensity spectrum and a change rule of the turbidity as related factors, and establishing a nitrate calculation model according to the attenuation coefficient and the turbidity calculation model. The method has the beneficial effects that the method is based on turbidity synchronous measurement, and integrates the common correction of temperature, salinity, pressure and turbidity compensated multi-environment factors, thereby remarkably improving the measurement accuracy of the nitrate measurement method.

Inventors

• ZHU XINGYUE
• WU QI
• ZHANG NAIXIN
• XU JIAN
• YANG BO

Assignees

• 南方海洋科学与工程广东省实验室(广州)
• 德州尧鼎光电科技有限公司

Dates

Publication Date

20260512

Application Date

20230518

Claims (1)

1. 1. The method for measuring the nitrate under high pressure based on turbidity compensation is characterized by comprising the following steps of: calculating the attenuation coefficients of standard seawater, turbidity and nitrate respectively based on the absorbance model; The turbidity under different measurement conditions is synchronously monitored based on multi-angle scattered light signals, and a turbidity calculation model is established by taking a light intensity spectrum and a change rule of the turbidity as related factors; Establishing a nitrate calculation model according to the attenuation coefficient and the turbidity calculation model; the establishment process of the absorbance model comprises the steps of respectively measuring the absorbance of standard seawater, standard seawater with turbidity and standard seawater with nitrate at different temperatures, salinity and pressures, and calculating to obtain the turbidity absorbance and the nitrate absorbance; the method for calculating the turbidity absorbance and the nitrate absorbance comprises the following steps: (1), (2), In the formula, Represents the nitrate absorbance at temperature T and pressure P, Represents the turbidity absorbance at temperature T and pressure P, Represents the absorbance of standard seawater with nitrate at temperature T and pressure P, Represents the absorbance of standard seawater having turbidity at temperature T and pressure P, Represents the absorbance of standard seawater at temperature T and pressure P; The method for calculating the attenuation coefficient comprises the following steps: (3), (4), (5), In the formula, Represents the attenuation coefficient of standard seawater at temperature T, pressure P and wavelength lambda, The attenuation coefficient representing turbidity at temperature T, pressure P and wavelength lambda, Represents the decay factor of the nitrate at temperature T, pressure P and wavelength lambda, To measure the optical path, S, 、 Respectively the salinity and turbidity concentration of standard seawater and the nitrate concentration; the turbidity calculation model building process comprises the following steps: (6), In the formula, Indicating turbidity at temperature T, pressure P and wavelength lambda, For a scattered light intensity with a scattering angle of 90, In order to transmit the intensity of light, For a scattered light intensity at a scattering angle of 30 deg. on the left side of the transmitted light, For a scattered light intensity at a scattering angle of 30 deg. on the right side of the transmitted light, For a scattered light intensity at a scattering angle of 30 deg. on the upper side of the transmitted light, For a scattered light intensity at a scattering angle of 30 deg. at the lower side of the transmitted light, Is that Is used to determine the fitting coefficients of (a), Is that Is used to determine the fitting coefficients of (a), Is that Is used to determine the fitting coefficients of (a), Is that Is used to determine the fitting coefficients of (a), Is that Fitting coefficients of (a); the nitrate calculation model building process comprises the following steps: (7), In the formula, For the salinity of the seawater to be measured, For the measurement of absorbance of the seawater to be measured, The absorbance of nitrate in the seawater to be detected; Absorbance of nitrate in seawater to be detected by multiple regression method And nitrate concentration And establishing the nitrate calculation model.

Description

Turbidity compensation-based nitrate measurement method under high pressure Technical Field The invention relates to the technical field of environment detection and analysis, in particular to a method for measuring nitrate under high pressure based on turbidity compensation. Background Currently, human understanding of the ecosystem in deep sea (0-6000 meters, equivalent to 0-60MPa pressure) remains blank. Nitrate is one of three nutrient salts of sea water, and accurate and effective determination of the content of nitrate can provide valuable data reference for research of marine ecological environment. Under different environmental conditions of deep sea, continuous space-time ecological observation data collection and statistical analysis are needed, and the current main research method and means for nitrate in seawater are to bring the seawater to a laboratory for measurement, or continuously observe nitrate in seawater of more than 2000 meters based on an in-situ sensor, so that the dynamic rule research of an ecological system in the deep sea environment cannot be satisfied. Therefore, the content and the change of the nitrate parameter in the deep sea environment (0-6000 m) are monitored in real time, and the method has important significance for the research of the deep sea ecological environment. Sakamoto et al 2017 published a pressure correction method "Pressure correction for the computation of nitrate concentrations in seawater usingan in situ ultraviolet spectrophotometer". for nitrate content in seawater within 20MPa, however, the correction method cannot be applied to nitrate content data correction and turbidity correction in pressure environments above 20MPa, and has limitations. Disclosure of Invention Aiming at the problems, the invention provides a method for measuring nitrate under high pressure based on turbidity compensation, which mainly solves the problems of the background technology. In order to solve the technical problems, the technical scheme of the invention is as follows: the method for measuring the nitrate under high pressure based on turbidity compensation comprises the following steps: Respectively calculating the attenuation coefficients of standard seawater, turbidity and nitrate based on a known absorbance model; The turbidity under different measurement conditions is synchronously monitored based on multi-angle scattered light signals, and a turbidity calculation model is established by taking a light intensity spectrum and a change rule of the turbidity as related factors; and establishing a nitrate calculation model according to the attenuation coefficient and the turbidity calculation model. In some embodiments, the absorbance model is constructed by measuring absorbance of standard seawater, standard seawater with turbidity, and standard seawater with nitrate at different temperatures, salinity, and pressures, respectively, and calculating turbidity absorbance and nitrate absorbance. In some embodiments, the turbidity absorbance and the nitrate absorbance are calculated by: Anit,T,P＝Anit_in_std,T,P-Astd,T,P (1), Aturb,T,P＝Aturb_in_std,T,P-Astd,T,P (2), Wherein a nit,T,P represents the nitrate absorbance at the temperature T and the pressure P, a turb,T,P represents the turbidity absorbance at the temperature T and the pressure P, a nit_in_std,T,P represents the absorbance of the standard seawater having the nitrate at the temperature T and the pressure P, a turb_in_std,T,P represents the absorbance of the standard seawater having the turbidity at the temperature T and the pressure P, and a std,T,P represents the absorbance of the standard seawater at the temperature T and the pressure P. In some embodiments, the method for calculating the attenuation coefficient is: Where ε std (T, P, λ) represents the attenuation coefficient of standard seawater at temperature T, pressure P and wavelength λ, ε turb (T, P, λ) represents the attenuation coefficient of turbidity at temperature T, pressure P and wavelength λ, and ε nit (P, λ) represents the attenuation coefficient of nitrate at temperature T, pressure P and wavelength λ, respectively, L is the measured optical path, S, C turb、Cnit is the salinity, turbidity concentration and nitrate concentration of standard seawater, respectively. In some embodiments, the creating the turbidity calculation model includes: wherein C turb (T, P, λ) represents turbidity at temperature T, pressure P and wavelength λ, I 90 is scattered light intensity with a scattering angle of 90 °, I t is transmitted light intensity, I fs1 is scattered light intensity with a scattering angle of 30 ° at the left side of transmitted light, I fs2 is scattered light intensity with a scattering angle of 30 ° at the right side of transmitted light, I fs3 is scattered light intensity with a scattering angle of 30 ° at the upper side of transmitted light, I fs4 is scattered light intensity with a scattering angle of 30 ° at the lower side of transmitted lig