Method for detecting and estimating atmospheric organic nitrate aerosols

Abstract

The application provides a detection and estimation method of atmospheric organic nitrate aerosol, comprising the following steps: using an aerosol mass spectrometer to continuously observe organic and inorganic components of non-refractory submicron aerosol in the atmosphere, obtaining time series of ion fragment mass spectrum of organic matter and concentration of inorganic ion fragments; combining time series of NO + , NO2 + fragments and ion fragment mass spectrum of organic matter, establishing an ORG NOx matrix containing NO + , NO2 + fragments; setting a fixed inorganic nitrate mass spectrum only composed of NO + and NO2 + fragments; using positive definite matrix factor analysis method to analyze the ORG NOx matrix, decomposing it into an INA factor representing inorganic nitrate only composed of NO + and NO2 + fragments in a set proportion, and several independent OA factors representing different OA emission sources and containing NO + , NO2 + fragments; using the concentration of each OA factor and the proportion of NO + and NO2 + ion fragments in the mass spectrum thereof to calculate the concentration of organic nitrate groups; thus, the accuracy of the analysis result of the concentration of atmospheric organic nitrate can be improved.

Description

Technical Field

[0001] This invention relates to the field of environmental science and protection technology, specifically to a method for detecting and estimating atmospheric organic nitrate aerosols. Background Technology

[0002] Fine particulate matter in the atmosphere is mainly composed of inorganic salts (nitrates, sulfates, and ammonium salts, etc.) and organic components. Nitrate, sulfate, and ammonium salt particles are also known as secondary inorganic aerosols (SNAs), which are NO... x Secondary pollutants are generated from gaseous precursors such as SO2 and NH3. Organic aerosols (OA) include primary organic aerosols (POA) directly emitted from pollution sources, as well as secondary organic aerosols (SOA) formed through physicochemical processes such as atmospheric oxidation, condensation, and aggregation. During severe haze events, a rapid increase in SNA and SOA concentrations is often observed, with SOA accounting for up to 90% of OA. SOA formation is also influenced by atmospheric oxidation, atmospheric humidity, and gaseous pollutants such as NO. x Influenced by numerous factors such as SNA particle species, many sulfur- and nitrogen-containing species are generated during its formation and aging process, making the mechanism extremely complex.

[0003] In many urban areas with high levels of motor vehicle activity, NO x It interacts significantly with gaseous organic pollutants, and under sunlight, it can cause secondary pollution such as SOA and O3. NO in the atmosphere... x When precursors such as NO3 free radicals and oxidants participate in the formation and aging of SOA (Organic Aerosols), they generate organic nitrates (RONO2) and organic peroxynitrates (RO2NO2), such as peroxyacetyl nitrate (PAN). These particulate organic nitrogen compounds (pON) contribute 5% to 77% of OA. pON is also an important sink for atmospheric nitrogen oxides, playing a significant role in the nitrogen oxide cycle. Nitrogen-containing organic compounds are also an important component of atmospheric brown carbon (BrC), which greatly affects the optical properties of aerosols and atmospheric radiation balance, thus further influencing regional and global climate. Therefore, the detection and quantification of nitrogen-containing organic compounds in the atmosphere are of great value for a comprehensive understanding of the composition of organic aerosols and for in-depth research into the formation mechanism of secondary organic aerosols.

[0004] Currently, regarding the organic nitrate group NO in pON substances... 3有机Commonly used methods for quantification include: direct determination using instruments such as thermal dissociation laser-induced fluorescence spectroscopy or thermal erosion aerosol mass spectrometry; or utilizing the ionization of inorganic and organic nitrates into NO in high-resolution time-of-flight aerosol mass spectrometry (HR-ToF-AMS). + and NO2 + The proportion of organic nitrates can be estimated by varying the fragment ratios, or by incorporating NO observed by AMS. + and NO2 + After the fragments were added to the organic component mass spectrometer, positive definite matrix factorial (PMF) analysis was used to resolve the inorganic and organic nitrates. The latter two methods are relatively simple, offer high temporal resolution for organic nitrate detection, and can be used for further analysis of the formation and changes of organic nitrates. However, these two methods have certain uncertainties in the estimation and resolution of organic nitrates. For example, when PMF analyzes nitrogen-containing organic factors and inorganic nitrate factors, NO in the inorganic nitrate factor is often present. + / NO2 + The fragment ratio and the NO after pure nitrate is broken down in AMS + / NO2 + The different proportions of fragments, and the fact that a small amount of organic fragments remain in the inorganic nitrate factor, lead to significant deviations in the differentiation and analysis of organic and inorganic nitrates, resulting in inaccurate organic nitrate concentration results. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention proposes a method for detecting and estimating atmospheric organic nitrate aerosols. This method improves the accuracy of atmospheric organic nitrate concentration analysis results, thereby helping us to more clearly understand the degree of atmospheric organic nitrate pollution and its high temporal resolution changes during heavily polluted days. It also facilitates in-depth research into the formation and aging mechanisms of nitrogen-containing organic aerosols, organic precursors, and NO. x The influence and interaction between inorganic pollutants.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows: This invention provides a method for detecting and estimating atmospheric organic nitrate aerosols, comprising the following steps: S1 used an aerosol mass spectrometer (AMS) to continuously observe the organic and inorganic components of non-refractory submicron-sized atmospheric aerosols, obtaining high-resolution concentration time series of organic ion fragment mass spectra and inorganic ion fragment concentration time series. S2 combined with NO + NO2 +Time series of ion fragment and organic ion fragment mass spectrometry were established to construct a system containing NO. + NO2 + The concentration matrix of organic ion fragments is ORG. NOx matrix; S3 sets a fixed inorganic nitrate mass spectrum, which consists only of NO. + and NO2 + It is composed of ion fragments in a fixed proportion; S4 uses positive definite matrix factor analysis (PMF) to analyze ORG. NOx The matrix is ​​analyzed and decomposed into a matrix consisting only of a set proportion NO. + and NO2 + The fragments represent the INA factor, which represents inorganic nitrates, and several independent components representing different OA emission sources, each containing a small amount of NO. + NO2 + The OA factor of fragments; S5 utilizes the concentrations of each OA factor obtained in step S4 and the NO concentration in their mass spectra. + and NO2 + The percentage of ionic fragments was calculated to obtain the organic nitrate group NO. 3有机 The concentration.

[0007] This invention proposes a method for detecting and estimating atmospheric organic nitrate aerosols, which can improve the accuracy of atmospheric organic nitrate concentration analysis results. This helps us to more clearly understand the degree of atmospheric organic nitrate pollution and its high temporal resolution changes during heavily polluted days, as well as to further explore the formation and aging mechanisms of nitrogen-containing organic aerosols, organic precursors, and NO. x The influence and interaction between inorganic pollutants.

[0008] As a preferred technical solution, the ORG established in step S2 NOx The matrix (t×m) has t rows, where t is the total number of data points, i.e., the total number of observation times. ORG NOx Each row of the matrix is ​​the NO obtained from the observation at the time corresponding to that row. + NO2 + The concentration composition of ion fragments and m-2 organic ion fragments with different mass-to-charge ratios.

[0009] As a preferred technical solution, the NO content of the inorganic nitrate mass spectrometer set in step S3 is... + and NO2 + The proportion of ion fragments is between 2.3 and 2.5.

[0010] As a preferred technical solution, step S4 utilizes positive definite matrix factor analysis (PMF) to analyze the ORG. NOxThe matrix is ​​analyzed and decomposed into a matrix consisting only of a set proportion NO. + and NO2 + The fragments represent the INA factor, which represents inorganic nitrates, and several independent components representing different OA emission sources, each containing a small amount of NO. + NO2 + The OA factor for fragments specifically includes the following steps: S401 establishes ORG NOx A two-dimensional bilinear model of the matrix is ​​constructed, and the mass spectra of the INA factor representing inorganic nitrates in the mass spectrometry matrix of the model are constrained. S402 performs weighted least squares analysis on the model established in step S401, iterating to reduce the weighted residual sum of squares (Q). When the Q value reaches its minimum, ORG... NOx All elements in the matrix conform to its expected error, thus yielding the expected value Q. exp value; S403 The total number of factors P is manually selected, and the Q value is used in conjunction with Q... exp The ratio of values ​​is used to evaluate the quality of the PMF analysis results of the positive definite matrix factor analysis method, and finally, one inorganic nitrate INA factor, one OA factor, a mass spectrometry matrix, and a concentration time series matrix are obtained.

[0011] As a preferred technical solution, step S401 contains NO. + NO2 + Organic ion fragment concentration matrix ORG NOx The two-dimensional bilinear model is as follows: TS in the above formula NOx The matrix (t×p) consists of the concentration time series of one inorganic nitrate (INA) factor and p-1 OA factors, where t is the total number of data points, i.e., the total number of observation times; MS NOx The matrix (p×m) consists of mass spectra of one inorganic nitrate (INA) factor and p-1 OA factors; E NOx The matrix (t×m) is the residual matrix; ORG NOx Each element in the matrix org ij Its composition is as follows: In the above formula, org ij For ORG NOx The element in the i-th row and j-th column of the matrix represents the observed mass concentration of ion fragment j at time i, including NO. + NO2 + Fragments and all organic ionic fragments; ts ip For matrix TSNOx The element in the i-th row and p-th column represents the mass concentration of a given factor p at time i, including the inorganic nitrate (INA) factor and other OA factors; ms pj For matrix MS NOx The element in the p-th row and j-th column represents the proportion of ion fragment j in the mass spectrum given factor p, including NO. + NO2 + Fragments and all organic ionic fragments, including inorganic nitrate INA factors and other OA factors; e ij For matrix E NOx The element in the i-th row and j-th column represents the fitting residual of ion fragment j at time i; P is the total number of factors, and P-1 is the total number of OA pollution sources; among them, the mass spectra of the P-1 OA factors are not restricted, while the mass spectra of the inorganic nitrate INA factor are taken from the fixed inorganic nitrate mass spectra set in step S3, and the variable range is set: f in the above formula j,INA The percentage of any ion fragment j in all ion fragments in the inorganic nitrate INA factor mass spectrometry resolved by PMF; f j,NO3 is the percentage of any ion fragment j in all ion fragments in the fixed inorganic nitrate mass spectrometer set in step S3; a is the maximum allowable variation in the percentage of each mass spectrometer fragment.

[0012] As a preferred technical solution, step S402 performs weighted least squares analysis on the model established in step S401, noting ORG. NOx It is a positive definite matrix, and the mass spectrometry (MS) is... NOx ) and time series (TS) NOx Each element in the matrix is ​​also non-negative; through continuous iteration, the weighted residual sum of squares (Q) is reduced. The formula for calculating Q is: σ in the above formula ij For ORG NOx In the matrix org ij Standard deviation of an element; e ij For matrix E NOx The element in the i-th row and j-th column represents the fitting residual of ion fragment j at time i; when the Q-value reaches its minimum, all elements in the matrix conform to their expected error, i.e., |e^(j-j)|. ij | / σ ij ≈1, thus obtaining the expected value Q. exp The expected value of Q is Q exp The calculation formula is: In the above formula, t represents ORG. NOx The number of rows in the matrix; m is ORG. NOx The number of columns in the matrix; P is the total number of factors.

[0013] As a preferred technical solution, in step S403, the total number of factors P is manually selected so that the final MS NOx The matrix yields an inorganic nitrate (INA) factor whose mass spectrum falls within the variable range of the fixed mass spectrum set in step S3 and contains no organic debris. The other P-1 OA factors can also be identified as representing organic aerosol pollution sources. The Q value should be as small as possible, and as the total number of factors continues to increase, Q / Q... exp The decrease in value is no longer significant; a factor may be split into two factors with strong collinearity; at this point, TS NOx The matrix provides the concentration time series of each factor.

[0014] As a preferred technical solution, in step S5, the concentrations of the P-1 OA factors obtained in step S4 and the NO concentration in their mass spectra are utilized. + and NO2 + The percentage of ionic fragments was calculated to obtain the organic nitrate group NO. 3有机 The concentration of organic nitrate groups NO 3有机 The formula for calculating the concentration is as follows: NO in the above formula 3有机,i NO 3有机 The mass concentration at time i; ts ip Given an OA factor p, the mass concentration at time i; ms pNO For a given OA factor p, in the mass spectrum of NO + Percentage of ion fragments; ms pNO2 For a given OA factor p, in the mass spectrum of NO2 + The proportion of ion fragments; Relating INA factor concentration with NO 3有机 The total concentrations of inorganic and organic nitrates were obtained by summing the concentrations and compared with the inorganic nitrate concentrations obtained by traditional aerosol mass spectrometry (AMS) data processing to verify the above analysis results.

[0015] The present invention provides a method for detecting and estimating atmospheric organic nitrate aerosols, which has the following beneficial effects: [The method is used to] detect and estimate bound NO... + NO2 +An improvement has been made to the AMS-PMF (Aerosol Mass Spectrometry-Positive Deterministic Matrix Factor Analysis) method for analyzing ion fragments and organic ion fragments. By fixing the mass spectral composition of inorganic nitrates during PMF analysis, the uncertainty of inorganic nitrate factors resolved by PMF is reduced, thereby improving the accuracy of atmospheric organic nitrate concentration analysis results. This is beneficial for a clearer understanding of the high temporal resolution changes in atmospheric organic nitrate pollution and for in-depth research into the formation and aging mechanisms of nitrogen-containing organic aerosols, organic precursors, and NO. x The influence and interaction between inorganic pollutants. Detailed Implementation

[0016] The preferred embodiments of the present invention are described in detail below.

[0017] It is understood that the present invention achieves its objectives through certain embodiments. The present invention provides a method for detecting and estimating atmospheric organic nitrate aerosols, comprising the following steps: S1 selected representative observation sites based on research needs, with no obvious pollution sources or obstructions in the surrounding area, and used an aerosol mass spectrometer (AMS) to continuously observe atmospheric non-refractory submicron-sized aerosols (NR-PM). 1.0 The organic and inorganic components were analyzed to obtain high-temporal-resolution mass spectrometry concentration time series of organic ion fragments and inorganic ion fragments. Typically, a set of mass spectrometry data was generated every minute, and during the observation season, 15 to 30 days of typical season were selected or continuous observations were conducted for the pollution process. S2 combined with NO + NO2 + Time series of ion fragment and organic ion fragment mass spectrometry were established to construct a system containing NO. + NO2 + The concentration matrix of organic ion fragments is ORG. NOx The matrix, specifically, is as follows: Because the AMS (Aerosol Mass Spectrometer) instrument uses a 70 eV electron bombardment process to break down all molecules when measuring aerosol components, inorganic nitrates such as nitrate ions (NO3) are included. - and the nitrate group NO in nitrogen-containing organic matter 3有机 They will all be broken into NO + and NO2 + Ion fragments; however, when processing AMS observation data, it is generally assumed that all NO is... + and NO2 + The ionic fragments all originated from inorganic nitrates, thus the inorganic nitrate NO3 was calculated. -This would lead to an overestimation of inorganic nitrate concentration and neglect of organic nitrate concentration; therefore, we will consider all NO concentrations as inaccurate. + and NO2 + The ion fragment concentration matrix ORG was established by analyzing the binding of ion fragments with organic ion fragments. NOx The matrix (t×m) has t rows, where t is the total number of data points, i.e., the total number of observation times. Each row of this matrix contains the NO values ​​observed at the corresponding time. + (Mass-to-charge ratio m / z is 29.99799), NO2 + (Mass-to-charge ratio m / z is 45.99290) Concentration composition of ion fragments and m-2 organic ion fragments with different mass-to-charge ratios; S3 sets a fixed inorganic nitrate mass spectrum, which consists only of NO. + (Mass-to-charge ratio m / z is 29.99799) and NO2 + Composed of ion fragments (mass-to-charge ratio m / z = 45.99290), and NO + and NO2 + The proportion of ion fragments was set at 2.4, because previous studies have shown that the NO content of pure ammonium nitrate aerosols is measured after being broken down in AMS. + / NO2 + The proportion is approximately 2.4; the proportion of ion fragments with other mass-to-charge ratios is 0. S4 uses positive definite matrix factor analysis (PMF) to analyze ORG. NOx The matrix is ​​analyzed and decomposed into a matrix consisting only of a set proportion NO. + and NO2 + The fragments consist of INA components representing inorganic nitrates, and several independent components representing different OA emission sources, each containing small amounts of NO. + NO2 + The OA factor for fragments is calculated using the following method: Establish a two-dimensional bilinear model (1) TS in Formula (1) NOx The matrix (t×p) consists of the concentration time series of one inorganic nitrate (INA) factor and p-1 OA factors, where t is the total number of data points, i.e., the total number of observation times; MS NOx The matrix (p×m) consists of mass spectra of one inorganic nitrate (INA) factor and p-1 OA factors; E NOx The matrix (t×m) is the residual matrix; ORG NOx Each element in the matrix org ij Its composition is as follows: (2) In formula (2), orgij For ORG NOx The element in the i-th row and j-th column of the matrix represents the observed mass concentration of ion fragment j at time i, including NO. + NO2 + Fragments and all organic ionic fragments; ts ip For matrix TS NOx The element in the i-th row and p-th column represents the mass concentration of a given factor p at time i, including the inorganic nitrate (INA) factor and other OA factors; ms pj For matrix MS NOx The element in the p-th row and j-th column represents the proportion of ion fragment j in the mass spectrum given factor p, including NO. + NO2 + Fragments and all organic ionic fragments, including inorganic nitrate INA factors and other OA factors; e ij For matrix E NOx The element in the i-th row and j-th column represents the fitting residual of ion fragment j at time i; P is the total number of factors, and P-1 is the total number of OA pollution sources; among them, the mass spectra of the P-1 OA factors are not restricted, while the mass spectra of the inorganic nitrate INA factor are taken from the fixed mass spectra set in step S3, and a certain range of variation is set: (3) f in formula (3) j,INA The percentage of any ion fragment j in all ion fragments in the inorganic nitrate INA factor mass spectrometry resolved by PMF; f j,NO3 is the proportion of any ion fragment j in all ion fragments in the fixed mass spectrometer set in step S3; 'a' is the maximum allowable change in the proportion of each mass spectrometer fragment, typically set to 10%. Furthermore, a weighted least squares analysis is performed on the above model, noting ORG. NOx It is a positive definite matrix, and the mass spectrometry (MS) is... NOx ) and time series (TS) NOx Each element in the matrix is ​​also non-negative; by iterating continuously, the weighted sum of squared residuals Q is reduced, and the formula for calculating the value of Q is: (4) σ in formula (4) ij For ORG NOx In the matrix org ij The standard deviation of the elements; when the Q value reaches its minimum, all elements in the matrix conform to their expected error, i.e., |e0|0. ij | / σ ij ≈1, at this time the expected value of Q is Q expThe calculation formula is as follows: (5) In formula (5), t represents ORG. NOx The number of rows in the matrix; m is ORG. NOx The number of columns in the matrix; P is the total number of factors; Using Q / Q exp The ratio is used to evaluate the quality of the PMF analysis results; the total number of factors P is manually selected to make the final MS... NOx The matrix yields an inorganic nitrate (INA) factor (whose mass spectra are within the variable range of the fixed mass spectra set in step S3, and do not contain organic debris). The other P-1 OA factors can also be identified as representing organic aerosol pollution sources. The Q value should be as small as possible, and Q / Q should be minimized as the total number of factors continues to increase. exp The decrease in value is no longer significant; a factor may be split into two factors with strong collinearity; at this point, TS NOx The matrix provides the concentration time series of each factor; typically, the above factor analysis process can be achieved using the PMF Evaluation Toolkit (PET, version 3.04) and the multilinear engine (ME-2) implementation. S5 utilizes the concentrations of the P-1 OA factors obtained in step S4 and the NO concentration in their mass spectra. + and NO2 + The percentage of ionic fragments was calculated to obtain the organic nitrate group NO. 3有机 The concentration is determined using the following method: The P-1 OA factors obtained in step S4 are the organic components in the aerosols observed by AMS, and a small amount of NO will still be present in their mass spectra. + and NO2 + Ion fragments, this part of NO + and NO2 + Ion fragments are thought to originate from organic nitrogen substances; therefore, NO can be determined based on the mass spectrometry of various OA factors. + and NO2 + The NO concentration at each time step was calculated using the proportion of ion fragments and the concentration of the OA factor. 3有机 Mass concentration, organic nitrate group NO 3有机 The formula for calculating the concentration is as follows: (6) NO in formula (6) 3有机,i NO 3有机 The mass concentration at time i; ts ip Given an OA factor p, the mass concentration at time i; mspNO For a given OA factor p, in the mass spectrum of NO + Percentage of ion fragments; ms pNO2 For a given OA factor p, in the mass spectrum of NO2 + The proportion of ionic fragments; furthermore, the total mass concentration of particulate organic nitrogen aerosol pON can be calculated using the empirical value of the relative molecular mass of pON, which is 200-300 g / mol. Furthermore, the INA factor obtained in step S4 represents the inorganic nitrate component in the aerosol observed by AMS, which does not contain organic fragments in its mass spectrum, and its NO content in the mass spectrum is [not specified]. + and NO2 + Ion fragments are believed to originate from inorganic nitrates; they can correlate INA factor concentration with NO. 3有机 The concentrations were summed to obtain the total concentration of inorganic and organic nitrates, and then compared with the inorganic nitrate NO3 concentration obtained from the traditional AMS data processing procedure. - The concentrations were compared to verify the above analysis results.

[0018] The present invention provides a method for detecting and estimating atmospheric organic nitrate aerosols, which has the following beneficial effects: [The method is used to] detect and estimate bound NO... + NO2 + An improvement has been made to the AMS-PMF (Aerosol Mass Spectrometry-Positive Deterministic Matrix Factor Analysis) method for analyzing ion fragments and organic ion fragments. By fixing the mass spectral composition of inorganic nitrates during PMF analysis, the uncertainty of inorganic nitrate factors resolved by PMF is reduced, thereby improving the accuracy of atmospheric organic nitrate concentration analysis results. This is beneficial for a clearer understanding of the high temporal resolution changes in atmospheric organic nitrate pollution and for in-depth research into the formation and aging mechanisms of nitrogen-containing organic aerosols, organic precursors, and NO. x The influence and interaction between inorganic pollutants.

[0019] It is understood that this invention has been described through some embodiments, and those skilled in the art will recognize that various changes or equivalent substitutions can be made to these features and embodiments without departing from the spirit and scope of this invention. Furthermore, under the teachings of this invention, these features and embodiments can be modified to adapt to specific situations and materials without departing from the spirit and scope of this invention. Therefore, this invention is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are protected by this invention. Furthermore, under the teachings of this invention, these features and embodiments can be modified to adapt to specific situations and materials without departing from the spirit and scope of this invention. Therefore, this invention is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are within the scope of protection of this invention.

Claims

1. A method for detecting and estimating atmospheric organic nitrate aerosols, characterized in that, Includes the following steps: S1 used an aerosol mass spectrometer (AMS) to continuously observe the organic and inorganic components of non-refractory submicron-sized atmospheric aerosols, obtaining high-resolution concentration time series of organic ion fragment mass spectra and inorganic ion fragment concentration time series. S2 combined with NO + NO2 + Time series of ion fragment and organic ion fragment mass spectrometry were established to construct a system containing NO. + NO2 + The concentration matrix of organic ion fragments is ORG. NOx matrix; S3 sets a fixed inorganic nitrate mass spectrum, which consists only of NO. + and NO2 + The ion fragments are composed of a fixed proportion; the NO content of the inorganic nitrate mass spectrometer set in step S3 is... + and NO2 + The proportion of ion fragments is between 2.3 and 2.

5. S4 uses positive definite matrix factor analysis (PMF) to analyze ORG. NOx The matrix is ​​analyzed and decomposed into a matrix consisting only of a set proportion NO. + and NO2 + The fragments represent the INA factor, which represents inorganic nitrates, and several independent components representing different OA emission sources, each containing a small amount of NO. + NO2 + The OA factor of fragments; S5 utilizes the concentrations of each OA factor obtained in step S4 and the NO concentration in their mass spectra. + and NO2 + The percentage of ionic fragments was calculated to obtain the organic nitrate group NO. 3有机 The concentration; In step S5, the concentrations of the P-1 OA factors obtained in step S4 and the NO concentration in their mass spectra are utilized. + and NO2 + The percentage of ionic fragments was calculated to obtain the organic nitrate group NO. 3有机 The concentration of organic nitrate groups NO 3有机 The formula for calculating the concentration is as follows: ； NO in the above formula 3有机,i NO 3有机 The mass concentration at time i; ts ip Given an OA factor p, the mass concentration at time i; ms pNO For a given OA factor p, in the mass spectrum of NO + The proportion of ion fragments; ms pNO2 For a given OA factor p, in the mass spectrum of NO2 + The proportion of ion fragments; Relating INA factor concentration with NO 3有机 The total concentrations of inorganic and organic nitrates were obtained by summing the concentrations and compared with the inorganic nitrate concentrations obtained by traditional aerosol mass spectrometry (AMS) data processing to verify the above analysis results.

2. The method for detecting and estimating atmospheric organic nitrate aerosols according to claim 1, characterized in that, The ORG established in step S2 NOx The matrix (t×m) has t rows, where t is the total number of data points, i.e., the total number of observation times. ORG NOx Each row of the matrix is ​​the NO obtained from the observation at the time corresponding to that row. + NO2 + The concentration composition of ion fragments and m-2 organic ion fragments with different mass-to-charge ratios.

3. The method for detecting and estimating atmospheric organic nitrate aerosols according to claim 1, characterized in that, In step S4, positive definite matrix factor analysis (PMF) is used to analyze ORG. NOx The matrix is ​​analyzed and decomposed into a matrix consisting only of a set proportion NO. + and NO2 + The fragments represent the INA factor, which represents inorganic nitrates, and several independent components representing different OA emission sources, each containing a small amount of NO. + NO2 + The OA factor for fragments specifically includes the following steps: S401 establishes ORG NOx A two-dimensional bilinear model of the matrix is ​​constructed, and the mass spectra of the INA factor representing inorganic nitrates in the mass spectrometry matrix of the model are constrained. S402 performs weighted least squares analysis on the model established in step S401, iterating to reduce the weighted residual sum of squares (Q). When the Q value reaches its minimum, ORG... NOx All elements in the matrix conform to its expected error, thus yielding the expected value Q. exp value; S403 The total number of factors P is manually selected, and the Q value is used in conjunction with Q... exp The ratio of values ​​is used to evaluate the quality of the PMF analysis results of the positive definite matrix factor analysis method, and finally the mass spectrometry matrix and concentration time series matrix of one inorganic nitrate INA factor and P-1 OA factor are obtained.

4. The method for detecting and estimating atmospheric organic nitrate aerosols according to claim 3, characterized in that, Step S401 contains NO + NO2 + Organic ion fragment concentration matrix ORG NOx The two-dimensional bilinear model is as follows: ； TS in the above formula NOx The matrix (t×p) consists of the concentration time series of one inorganic nitrate (INA) factor and p-1 OA factors, where t is the total number of data points, i.e., the total number of observation times; MS NOx The matrix (p×m) consists of mass spectra of one inorganic nitrate (INA) factor and p-1 OA factors; E NOx The matrix (t×m) is the residual matrix; ORG NOx Each element in the matrix org ij Its composition is as follows: ； In the above formula, org ij For ORG NOx The element in the i-th row and j-th column of the matrix represents the observed mass concentration of ion fragment j at time i, including NO. + NO2 + Fragments and all organic ionic fragments; ts ip For matrix TS NOx The element in the i-th row and p-th column represents the mass concentration of a given factor p at time i, including the inorganic nitrate INA factor and other OA factors. ms pj For matrix MS NOx The element in the p-th row and j-th column represents the proportion of ion fragment j in the mass spectrum given factor p, including NO. + NO2 + Fragments and all organic ionic fragments, including inorganic nitrate INA factors and other OA factors; e ij For matrix E NOx The element in the i-th row and j-th column represents the fitting residual of ion fragment j at time i; P is the total number of factors, and P-1 is the total number of OA pollution sources; the mass spectra of the P-1 OA factors are not restricted, while the mass spectra of the inorganic nitrate INA factor are taken from the fixed inorganic nitrate mass spectra set in step S3, and the variable range is set: ； f in the above formula j,INA The percentage of any ion fragment j in all ion fragments in the inorganic nitrate INA factor mass spectrometry resolved by PMF; f j,NO3 is the percentage of any ion fragment j in all ion fragments in the fixed inorganic nitrate mass spectrometer set in step S3; a is the maximum allowable variation in the percentage of each mass spectrometer fragment.

5. The method for detecting and estimating atmospheric organic nitrate aerosols according to claim 4, characterized in that, In step S402, a weighted least squares analysis is performed on the model established in step S401. Note the ORG... NOx The matrix is ​​positive definite, and each element in the mass spectrum and time series matrices is also non-negative. Through continuous iteration, the weighted residual sum of squares (Q) is reduced. The formula for calculating Q is: ； σ in the above formula ij For ORG NOx In the matrix org ij Standard deviation of an element; e ij For matrix E NOx The element in the i-th row and j-th column represents the fitting residual of ion fragment j at time i; when the Q-value reaches its minimum, all elements in the matrix conform to their expected error, i.e., |e^(j-j)|. ij | / σ ij ≈1, thus obtaining the expected value Q. exp Q exp The calculation formula is: ； In the above formula, t represents ORG. NOx The number of rows in the matrix; m is ORG. NOx The number of columns in the matrix; P is the total number of factors.

6. The method for detecting and estimating atmospheric organic nitrate aerosols according to claim 5, characterized in that, In step S403, the total number of factors P is manually selected so that the final MS NOx The matrix yields an inorganic nitrate (INA) factor whose mass spectrum falls within the variable range of the fixed mass spectrum set in step S3 and contains no organic debris. The other P-1 OA factors can also be identified as representing organic aerosol pollution sources. The Q value should be as small as possible, and as the total number of factors continues to increase, Q / Q... exp The decrease in value is no longer significant; a factor may be split into two factors with strong collinearity; at this point, TS NOx The matrix provides the concentration time series of each factor.

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