Methods for estimating secondary organic carbon concentrations

Abstract

The present invention relates to the field of environmental monitoring, and in particular to a method for estimating secondary organic carbon concentration, comprising the steps of: (A1) obtaining OC and EC in atmospheric particulate matter within a first period T1; and simultaneously obtaining multiple wavelengths λ within a second period T2. s Absorption coefficient b s and BC; (A2) according to the absorption coefficient b s Obtain BC1 and BC2; (A3) Obtain the minimum value A of m OC / (BC2·EC); (A4) a increases from 0 to A according to the step size d, and a i The corresponding c i ;(A5)For each array (a i ,c i ), calculate m groups BC / EC and OC / ( a i BC1 EC +c i ·BC2·EC) corresponding correlation coefficient r i , r i Maximum and array (a j ,c j ) corresponds to; (A6) secondary organic carbon concentration SOC = OC-c j ·BC2·EC‑ a j ·BC1·EC. The present invention has the advantages of accurate estimation and is applied in environmental monitoring.

Description

Technical Field

[0001] The present invention relates to the field of environmental protection, and in particular to a method for estimating secondary organic carbon concentration. Background Art

[0002] Carbonaceous aerosols are a significant component of atmospheric particulate matter, primarily existing in the form of organic carbon (OC) and elemental carbon (EC). OC has complex origins, including primary organic carbon (POC) and secondary organic carbon (SOC), both emitted directly into the atmosphere from pollution sources. EC, on the other hand, primarily originates from the incomplete combustion of fossil fuels and biomass, and is emitted directly from pollution sources, making it relatively stable in the atmosphere.

[0003] In recent years, SOC has become an important component of fine particulate matter in my country. Understanding the contribution and concentration characteristics of SOC is crucial for formulating governance strategies. SOC is mainly generated by volatile organic compounds through complex chemical reaction processes. Its chemical composition is complex and its content is difficult to measure directly. It is generally obtained through indirect estimation. Among them, the minimum ratio method is widely used for SOC estimation due to its simple principle. This method assumes that the emission characteristics of the primary emission source of carbonaceous aerosol, POC / EC, are fixed. The main shortcomings of this method are:

[0004] For primary emission sources of carbonaceous aerosols, the emission characteristics of fossil fuel combustion and biomass combustion are quite different, and the emission contribution is also constantly changing. Therefore, the POC / EC ratio of primary emission sources changes over time and is not a fixed value. In particular, when using high-temporal-resolution (1-hour) OCEC monitoring data to estimate SOC, determining POC / EC as a fixed value for SOC estimation will result in large errors. Summary of the Invention

[0005] In order to solve the deficiencies in the above-mentioned prior art solutions, the present invention provides a method for estimating the concentration of secondary organic carbon.

[0006] The purpose of the present invention is achieved through the following technical solutions:

[0007] A method for estimating secondary organic carbon concentration comprises the following steps:

[0008] (A1) Obtain the OC and EC of atmospheric particulate matter in m first periods T1; at the same time, obtain the OC and EC of atmospheric particulate matter in n second periods T2 at multiple wavelengths λ s Absorption coefficient b s and BC, n>m, T1> T2, s=1,2···M;

[0009] (A2) According to the absorption coefficient b s Obtain BC1 and BC2 corresponding to each first period T1;

[0010] BC1 is the contribution of biomass combustion to BC, and BC2 is the contribution of fossil fuel combustion to BC;

[0011] (A3) Obtain the minimum value A of m OC / (BC1·EC);

[0012] (A4) a increases from 0 to A according to the step size d, and a i The corresponding m (OC-a i The minimum value of (BC1·EC) / (BC2·EC) is taken as c i , i=1,2···N, N=[A / d];

[0013] (A5) For each array (a i ,c i ), calculate m groups BC / EC and OC / ( a i BC1 EC +c i ·BC2·EC) corresponding correlation coefficient r i , r i Maximum and array (a j ,c j )correspond;

[0014] (A6) Secondary organic carbon concentration SOC = OC- c j BC2 EC-a j ·BC1·EC.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] Introducing BC source apportionment technology into SOC estimation reduces the error caused by changes in pollution source emission contributions when using the minimum ratio method, making the SOC estimated concentration closer to the actual level.

[0017] Provides methods to estimate carbon component emission characteristics of fossil fuel combustion and biomass combustion. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The disclosure of the present invention will become more easily understood with reference to the accompanying drawings. Those skilled in the art will readily appreciate that these drawings are merely used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention.

[0019] Figure 1 4 is a flow chart of a method for estimating secondary organic carbon concentration according to an embodiment of the present invention. DETAILED DESCRIPTION

[0020] Figure 1The following description describes optional embodiments of the present invention to teach those skilled in the art how to implement and reproduce the present invention. In order to explain the technical solution of the present invention, some conventional aspects have been simplified or omitted. Those skilled in the art will understand that variations or substitutions derived from these embodiments will be within the scope of the present invention. Those skilled in the art will understand that the following features can be combined in various ways to form multiple variations of the present invention. Therefore, the present invention is not limited to the following optional embodiments, but is only limited by the claims and their equivalents.

[0021] Example 1.

[0022] The method for estimating the secondary organic carbon concentration in the embodiment of the present invention is as follows: Figure 1 As shown, the method includes the following steps:

[0023] (A1) Obtain the OC and EC of atmospheric particulate matter in m first periods T1; at the same time, obtain the OC and EC of atmospheric particulate matter in n second periods T2 at multiple wavelengths λ s Absorption coefficient b (including near ultraviolet and near infrared wavelengths) s and BC, n>m, T1> T2, s=1,2···M;

[0024] (A2) According to the absorption coefficient b s Obtain BC1 and BC2 corresponding to each first period T1;

[0025] BC1 is the contribution of biomass combustion to BC, and BC2 is the contribution of fossil fuel combustion to BC;

[0026] (A3) Obtain the minimum value A of m OC / (BC1·EC);

[0027] (A4) a increases from 0 to A according to the step size d, and a i The corresponding m (OC-a i The minimum value of (BC1·EC) / (BC2·EC) is taken as c i , i=1,2···N, N=[A / d];

[0028] (A5) For each array (a i ,c i ), calculate m groups BC / EC and OC / ( a i BC1 EC +c i ·BC2·EC) corresponding correlation coefficient r i , r i Maximum and array (a j ,c j )correspond;

[0029] (A6) Secondary organic carbon concentration SOC = OC- c j BC2 EC-a j ·BC1·EC.

[0030] In order to obtain accurate BC1 and BC2, in step (A2), BC1 and BC2 corresponding to each second period T2 are obtained, and the average values ​​of BC1 and BC2 of multiple second periods T2 within each first period T1 are respectively used as BC1 and BC2 of the first period T1.

[0031] In order to obtain accurate BC1 and BC2 of each second period T2, the method of obtaining BC1 and BC2 includes the following steps:

[0032] (B1) According to the absorption coefficient b s and wavelength λ s , obtain the coefficient k and absorption index α corresponding to each second period T2, α bb =(α) max ;

[0033] (B2) Based on the data collected in each second cycle, coefficient k and α bb ,use Get the k corresponding to each second period T2 ff ;

[0034] (B3) Obtain k corresponding to each second period T2 bb =kk ff ;

[0035] (B4) obtaining BC1 and BC2 corresponding to each second period T2;

[0036] , .

[0037] In order to obtain accurate coefficient k and absorption index α, in step (A1), according to the absorption coefficient b of each second period T2 s and wavelength λ s , using b(λ)=k·λ -α , the fitting coefficient k and absorption index α are obtained.

[0038] Example 2.

[0039] An example of application of the method for estimating secondary organic carbon concentration according to Example 1 of the present invention in atmospheric monitoring.

[0040] In this application example, Figure 1 As shown, the method includes the following steps:

[0041] (A1) Obtain OC and EC in atmospheric particulate matter for 29 first cycles T1 = 1 hour;

[0042] At the same time, 348 second cycles T2 = 5 minutes, 2 wavelengths λ s (including near-ultraviolet 370nm and near-infrared 880nm) absorption coefficient b 370 、b 880 and BC.

[0043] (A2) Each first period T1 corresponds to 12 second periods T2, 12 absorption coefficients b 370 、b 880 The average value of BC is taken as b in the first cycle. 370 、b 880 and BC, see Table 1.

[0044] Calculate the contribution of biomass combustion to BC as BC1 and the contribution of fossil fuel combustion to BC as BC2 according to the following formula.

[0045] , BC2=1- BC1. See Table 1 for the obtained results.

[0046] (A3) Obtain the OC / (BC1·EC) corresponding to each first period T1. A is the minimum value among the 29 OC / (BC1·EC), which is 11.4.

[0047] Table 1. Data table for multiple first and second cycles.

[0048] .

[0049] (A4) a increases from 0 to 11.4 in steps of 1, and i The corresponding 29 (OC-a i The minimum value of (BC1·EC) / (BC2·EC) is taken as c i , i=1,2···11.

[0050] For example, when a1=1, (OC-a i The values ​​of (·BC1·EC) / (BC2·EC) for the 29 data points in column 1 (one data point for each first period T1) are 3.24, 3.59, 3.12, 3.40, and 3.44, respectively. The minimum value, 3.12, is used as c1. The results are shown in Table 2.

[0051] Table 2. Get array (a i ,c i ) data table.

[0052]

[0053] (A5) For each array (a i ,c i ), in each first cycle T1, a group of BC / EC and D=OC / (a i BC1 EC+c i ·BC2·EC) corresponds to, therefore, each array (a i ,c i ) corresponds to 29 groups of BC / EC and OC / (a i BC1 EC+c i ·BC2·EC), the BC / EC corresponding to each first period T1 is shown in Table 1, and D is shown in Table 3, and each array (a i ,c i ) under the corresponding BC / EC, D correlation coefficient r i .

[0054] Table 3. Array (a i ,c i ) corresponds to D of each first period T1.

[0055]

[0056] According to the above method, 11 r i , as shown in Figure 4, r i The maximum value (i.e. 0.849) corresponds to the array (7,1.44).

[0057] Table 4. Array (a i ,c i ) and r i Correspondence table between them.

[0058]

[0059] (A5) Calculate the SOC concentration: SOC = OC - 1.44 · BC2 · EC - 7 · BC1 · EC. The SOC corresponding to each first cycle T1 is shown in Table 5.

[0060] Table 5. SOC data table corresponding to each first cycle T1.

[0061] .

[0062] Example 3.

[0063] The application example of the method for estimating secondary organic carbon concentration according to Example 1 of the present invention is different from Example 2 in that:

[0064] In step (A2), according to b of each second period T2 370 、b880 The BC1 and BC2 corresponding to the second period are obtained by the calculation formula.

[0065] There are 348 BC1s and BC2s corresponding to each second period T2, each first period T1 corresponds to 12 second periods T2, and the average value of BC1s and BC2s corresponding to the 12 second periods T2 is used as the BC1 and BC2 corresponding to each first period T1.

[0066] Example 4.

[0067] The application example of the method for estimating secondary organic carbon concentration according to Example 1 of the present invention in atmospheric monitoring is different from that of Example 2 in that:

[0068] In step (A1), within each second period T2, the absorption coefficients of 7 wavelengths are obtained, and the absorption coefficient b corresponds to the wavelength λ, i=1,2…7, λ1=0.88μm, λ2=0.37μm, λ3=0.47μm, λ4=0.52μm, λ5=0.59μm, λ6=0.66μm, λ7=0.95μm.

[0069] In step (A2), the method of obtaining BC1 and BC2 corresponding to each second period T2 is:

[0070] (B1) According to the 7 absorption coefficients b and wavelengths λ collected in each second period T2, b(λ)=k·λ is used. -α , the coefficient k and absorption index α corresponding to each second period T2 are obtained by fitting, α bb =(α) max , that is, 348 second periods T2 correspond to α bb .

[0071] (B2) Based on the absorption coefficient b and wavelength λ, coefficient k and α collected in each second period T2 bb ,use , the fitting results in the k corresponding to each second period T2 ff .

[0072] (B3) Obtain k corresponding to each second period T bb =kk ff .

[0073] (B4) Obtain the contribution ratio BC1 of biomass to the black carbon concentration BC and the contribution ratio BC2 of fossil fuel to the black carbon concentration BC corresponding to each second period T.

[0074] , , where λ=0.88μm.

[0075] In this way, 348 BC1s and BC2s corresponding to each second period T2 are obtained. Each first period T1 corresponds to 12 second periods T2, and the average of the BC1s and BC2s corresponding to these 12 second periods T2 is used as the BC1 and BC2 corresponding to each first period T1.

Claims

1. A method for estimating secondary organic carbon concentration, characterized in that: The method comprises the following steps: (A1) Obtain the OC and EC of atmospheric particulate matter in m first periods T1; at the same time, obtain the OC and EC of atmospheric particulate matter in n second periods T2 at multiple wavelengths λ s Absorption coefficient b s and BC, n>m, T1> T2, s=1,2···M; (A2) According to the absorption coefficient b s Obtain BC1 and BC2 corresponding to each first period T1; BC1 is the contribution of biomass combustion to BC, and BC2 is the contribution of fossil fuel combustion to BC; (A3) Obtain the minimum value A of m OC / (BC1·EC); (A4) a increases from 0 to A according to the step size d, and a i The corresponding m (OC-a i The minimum value of (BC1·EC) / (BC2·EC) is taken as c i , i=1,2···N, N=[A / d]; (A5) For each array (a i ,c i ), calculate m groups BC / EC and OC / ( a i BC1 EC +c i ·BC2·EC) corresponding correlation coefficient r i , r i Maximum and array (a j ,c j )correspond; (A6) Secondary organic carbon concentration SOC = OC- c j BC2 EC-a j ·BC1·EC.

2. The method for estimating secondary organic carbon concentration according to claim 1, characterized in that: The multiple wavelengths are respectively in the near ultraviolet band and the near infrared band.

3. The method for estimating secondary organic carbon concentration according to claim 1, characterized in that: In step (A2), BC1 and BC2 corresponding to each second period T2 are obtained, and average values ​​of BC1 and BC2 of a plurality of second periods T2 within each first period T1 are respectively taken as BC1 and BC2.

4. The method for estimating secondary organic carbon concentration according to claim 3, characterized in that: The method of obtaining BC1 and BC2 corresponding to each second period T2 includes the following steps: (B1) According to the absorption coefficient b s and wavelength λ s , obtain the coefficient k and absorption index α corresponding to each second period T2, α bb =(α) max ; (B2) Based on the data collected in each second period T2, the coefficient k and α bb ,use Get the k corresponding to each second period T2 ff ; (B3) Obtain k corresponding to each second period T2 bb =kk ff ; (B4) obtaining BC1 and BC2 corresponding to each second period T2; ， 。 5. The method for estimating secondary organic carbon concentration according to claim 4, characterized in that: In step (B4), λ = 0.88 μm.

6. The method for estimating secondary organic carbon concentration according to claim 4, characterized in that: In step (A1), according to the absorption coefficient b of each second period T2 s and wavelength λ s , using b(λ)=k·λ -α , the fitting coefficient k and absorption index α are obtained.

7. The method for estimating secondary organic carbon concentration according to claim 4, characterized in that: M=7, λ1=0.88μm, λ2=0.37μm, λ3=0.47μm, λ4=0.52μm, λ5=0.59μm, λ6=0.66μm, λ7=0.95μm.

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