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CN-121978189-A - River denitrification rate evaluation method based on high-frequency dissolved oxygen monitoring

CN121978189ACN 121978189 ACN121978189 ACN 121978189ACN-121978189-A

Abstract

The invention discloses a method for obtaining denitrification rate based on river dissolved oxygen high-frequency monitoring, which comprises the steps of S1, constructing a dynamic response model of river denitrification rate on iso-oxygen respiration, S11, carrying out in-situ high-frequency DO observation of different types of rivers, collecting water samples, measuring the concentration of dissolved N 2 and O 2 of the collected water samples by adopting a MIMS technology, S12, calculating the river iso-oxygen respiration rate through an O 2 mass balance model based on O 2 concentration data, S13, calculating the river denitrification rate through an N 2 mass balance model based on N 2 concentration data, S14, fitting the obtained series of iso-oxygen respiration rates with the denitrification rate, and simulating the river denitrification rate through the constructed dynamic response model based on field real-time high-frequency monitoring of dissolved oxygen observation data. The invention solves the problems of high cost and incapability of real-time continuous monitoring of the traditional denitrification rate measurement, and realizes in-situ, real-time and high-frequency monitoring of the denitrification rate.

Inventors

  • ZHANG PEIPEI
  • WANG DONGSHENG

Assignees

  • 浙江大学长三角智慧绿洲创新中心

Dates

Publication Date
20260505
Application Date
20251212

Claims (5)

  1. 1. The method for measuring the denitrification rate based on river dissolved oxygen high-frequency monitoring is characterized by comprising the following steps of: S1, constructing a dynamic response model of river denitrification rate to iso-oxygen respiration; S11, developing in-situ high-frequency dissolved oxygen observation of different types of rivers, collecting water samples, and measuring the concentration of dissolved N 2 and O 2 of the collected water samples by adopting a MIMS technology; S12, calculating the river iso-oxygen respiration rate through an O 2 mass balance model based on the O 2 concentration data measured by the MIMS technology in the step S11; S13, calculating the river denitrification rate through an N 2 mass balance model based on the N 2 concentration data measured by the MIMS technology in the step S11; s14, fitting a series of iso-oxygen respiration rates obtained in the steps S12 and S13 with a denitrification rate, wherein a dynamic response model between the denitrification rate and the iso-oxygen respiration is expressed as follows: (1) Wherein, the Is the denitrification rate of the river, Is the rate of respiration of iso-oxygen, Is the maximum denitrification rate and is used for the treatment of the wastewater, Is a half-saturation constant; s2, simulating the denitrification rate of the river by using the dynamic response model constructed in the step S1 based on field real-time high-frequency monitoring dissolved oxygen observation data.
  2. 2. The method for determining denitrification rate based on high-frequency monitoring of dissolved oxygen in river as claimed in claim 1, wherein in step S12, the oxygen respiration rate of river is estimated based on the concentration of O 2 obtained by MIMS according to the mass balance model of O 2 , and the specific formula is as follows: (2) (3) Wherein, the The concentration of O 2 at time t; Is river depth; Is the time step; is the photosynthetic active radiant flux density at time t; Is primary productivity; Is the ecosystem respiration; is the total daily solar radiation; Is the dissolved oxygen equilibrium concentration at the corresponding temperature and pressure at the moment t; is the exchange rate of O 2 ; is obtained by Schmitt number at t By the following constitution The calculated O 2 gas exchange rate; Is a standardized gas exchange rate, in particular to a gas transmission rate under ideal conditions that the water temperature is 20 ℃ and the Schmitt number (Sc) is 600; for the Schmitt coefficient, 2/3 is taken when the wind speed is less than 3.6 m s -1 , and 1/2 is taken when the wind speed is more than 3.6 m s -1 ; Is the schmitt constant of O 2 at a particular temperature, and the schmitt constant of fresh water is a function of temperature.
  3. 3. A method for determining denitrification rate based on high frequency monitoring of dissolved oxygen in a river as claimed in claim 2 wherein the differential oxygen respiration rate is obtained by subtracting autotrophic respiration from ecosystem respiration, specifically as follows: (4) is the rate of iso-oxygen respiration, i.e. ER-removal autotrophic respiration AR as part of GPP Is acquired.
  4. 4. The method for determining the denitrification rate based on the high-frequency monitoring of the dissolved oxygen in the river according to claim 1, wherein in the step S13, the denitrification rate of the river is estimated based on the concentration of N 2 obtained by MIMS according to the mass balance model of N 2 , and the specific formula is as follows: (5) (6) Wherein, the N 2 is the concentration at time t; is the denitrification rate; Is river depth; N 2 equilibrium concentration at the corresponding temperature and pressure at time t; is obtained by Schmitt number at t By the following constitution Calculating the obtained N 2 gas exchange rate; is the schmitt constant of N 2 at a particular temperature, the schmitt constant of fresh water being a function of temperature; The posterior distribution of (2) is estimated based on the model in step 102, and the denitrification rate and gas exchange rate for each sample is based on a Bayesian simulation analysis of Markov chain Monte Carlo.
  5. 5. The method for determining the denitrification rate based on river dissolved oxygen high frequency monitoring according to claim 1, wherein the time interval of collecting the water sample is not more than 4 hours.

Description

River denitrification rate evaluation method based on high-frequency dissolved oxygen monitoring Technical Field The invention belongs to the technical field of denitrification rate measurement, and particularly relates to a river denitrification rate evaluation method based on high-frequency dissolved oxygen monitoring. Background Denitrification is one of the key processes of nitrogen circulation in aquatic ecosystems, and specifically refers to a process of reducing nitrate or nitrite into gaseous nitrogen (such as nitrous oxide and nitrogen) by microorganisms under anoxic conditions. The accurate quantification of denitrification rate is a scientific basis for evaluating the self-cleaning capability of water bodies, tracing the emission of greenhouse gas nitrous oxide and formulating an eutrophication treatment strategy. However, the increasing human activity results in a continuous rise in basin nitrogen load, making accurate assessment of denitrification rates more challenging. The technical bottleneck directly restricts the accurate construction of the water environment nitrogen circulation model, and also influences the effective restoration of the high-nitrate water body. Currently, mainstream measurement techniques have limitations in that membrane-injection mass spectrometry (MIMS) techniques can be monitored in situThe method has the advantages of high-frequency measurement of Ar ratio, high equipment cost, high technical threshold, high isotope tracing method (such as 15 N) precision, extremely high cost and dependence on an ex-situ culture experiment, and low cost and mature application of acetylene inhibition method, but the added inhibitor can interfere with the microbial process (such as inhibition of nitrification) and possibly cause underestimation of the speed and failure in a sulfate reduction environment. In summary, the existing method has common defects of high cost, complex operation or difficulty in realizing in-situ continuous monitoring, and seriously hinders the deep understanding of the space-time dynamics of the denitrification process of the water ecosystem. Therefore, developing a new technology for denitrification rate that can achieve low cost, in situ, high frequency, continuous monitoring has become an urgent need in the art. Disclosure of Invention In order to solve the technical problems in the prior art, the invention provides a river denitrification rate evaluation method based on high-frequency dissolved oxygen monitoring. The method aims at rivers with different land utilization types in source river basin dimensions, based on in-situ high-frequency DO concentration monitoring, a membrane sample injection mass spectrometer technology is used for evaluating river iso-oxygen respiration and denitrification rates, and the process of iso-oxygen respiration and denitrification is coupled, so that a dynamic model between DO and denitrification rates is constructed, and river denitrification rate measurement on high-resolution space-time scale is realized. The technical scheme adopted by the invention is as follows: the method for measuring the denitrification rate based on river dissolved oxygen high-frequency monitoring is characterized by comprising the following steps of: S1, constructing a dynamic response model of river denitrification rate to iso-oxygen respiration; S11, developing in-situ high-frequency DO observation of different types of rivers, collecting water samples, and measuring the concentration of dissolved N 2 and O 2 of the collected water samples by adopting a MIMS technology; S12, calculating the river iso-oxygen respiration rate through an O 2 mass balance model based on the O 2 concentration data measured by the MIMS technology in the step S11; S13, calculating the river denitrification rate through an N 2 mass balance model based on the N 2 concentration data measured by the MIMS technology in the step S11; s14, fitting a series of iso-oxygen respiration rates obtained in the steps S12 and S13 with a denitrification rate, wherein a dynamic response model between the denitrification rate and the iso-oxygen respiration is expressed as follows: (1) Wherein, the Is the denitrification rate of the river,Is the rate of respiration of iso-oxygen,Is the maximum denitrification rate and is used for the treatment of the wastewater,Is a half-saturation constant; s2, simulating the denitrification rate of the river by using the dynamic response model constructed in the step S1 based on field real-time high-frequency monitoring dissolved oxygen observation data. Further, in step S12, based on the concentration of O 2 obtained by MIMS, the river iso-oxygen respiration rate is estimated according to the mass balance model of O 2, and the specific formula is as follows: (2) (3) Wherein, the The concentration of O 2 at time t; Is river depth; Is the time step; is the photosynthetic active radiant flux density at time t; Is primary productivity; Is the ecosys