An indoor measurement method for the scattering coefficient of unit concentration of heavy metal solutions

Abstract

The invention discloses an indoor measurement method of the scattering coefficient of the unit concentration direction of a heavy metal solution, which relates to the technical field of water environment remote sensing, including setting a radiance measuring device; using the radiance measuring device to sequentially measure the standard plate reflection radiance, the standard plate-glass composite reflection radiance, the pure water scattered radiance and the heavy metal solution scattered radiance to be measured; and calculating the unit concentration directional scattering coefficient of the heavy metal solution to be measured according to the standard plate reflection radiance, the standard plate-glass composite reflection radiance, the pure water scattered radiance and the heavy metal solution scattered radiance to be measured. The present invention does not need to rely on a specific natural water body in the wild, and at the same time takes into account the influence of the bottom reflected light of the standard plate and the glass composite structure, has strong universality, and realizes the accurate measurement of the unit concentration directional scattering coefficient of the heavy metal solution in the indoor environment.

Description

Technical Field

[0001] The invention relates to the technical field of water environment remote sensing, and more specifically to an indoor measurement method for the directional scattering coefficient per unit concentration of a heavy metal solution. Background Art

[0002] The optical parameters of water components are important basic parameters in water quality remote sensing models, including absorption coefficient, scattering coefficient, extinction coefficient, etc. When the incident light hits the particles in the water body, scattering and absorption will occur. The intensity is expressed by the scattering coefficient and the absorption coefficient. The sum of the scattering coefficient and the absorption coefficient is called the extinction coefficient. Among them, the scattering coefficient contains the sum of the scattered energy in all directions of the 4π spherical space, and the directional scattering coefficient is used to characterize the scattering intensity of the incident light passing through the particles in a certain scattering angle direction. This parameter is particularly important for measuring the ability of satellite sensors to receive back reflections. Until now, the academic community has not given a universal measurement method for the scattering coefficient and directional scattering coefficient of heavy metal solutions, which has brought inconvenience to the application of water quality remote sensing models for heavy metal concentration inversion.

[0003] The prior art discloses a method for measuring the absorption coefficient and scattering coefficient of water quality components. The scattering coefficient is calculated by combining the field measurement of the off-water reflectance and the indoor measurement of the water sample extinction coefficient. However, the following improvements can still be made: first, the comparison document needs to select a typical single type of polluted water body in the field, but there is no absolute "typical single type of pollution" in natural water bodies. Therefore, the scattering coefficient calculated by the comparison document only represents the comprehensive optical properties of the characteristic type of water body in the field, and cannot be accurate to a certain compound component. The calculated result will be larger than the actual component to be measured; secondly, the measurement of For example, in the case of polluted natural water bodies in the wild, the concentration of components needs to be obtained through testing. The number of components tested is limited, and there are uncertain components that are ignored. The optical parameters of the components are calculated using this concentration, and the calculated results are smaller than the components that are actually expected to be measured. Finally, when selecting field sample points to measure the reflectivity off water, the comparative document assumes that the optical thickness of the water body on site is extremely large, and ignores the reflected light from the bottom of the water. Therefore, it is only applicable to deep water or poor water quality, not shallow water. In addition, the device designed in the comparative document is used to measure the total extinction coefficient of the water body, not the scattering coefficient or directional scattering coefficient. Therefore, the comparative document cannot accurately measure the unit concentration directional scattering coefficient of the heavy metal solution in an indoor environment. Summary of the invention

[0004] In order to overcome the defect that the above-mentioned prior art cannot accurately measure the unit concentration directional scattering coefficient of a heavy metal solution in an indoor environment, the present invention provides an indoor measurement method for the unit concentration directional scattering coefficient of a heavy metal solution. The method is not limited by the water environment of the heavy metal solution to be measured, the number or concentration of specific components of the heavy metal solution to be measured, has strong universality, and can achieve accurate measurement of the unit concentration directional scattering coefficient of the heavy metal solution in an indoor environment.

[0005] In order to solve the above technical problems, the technical solution of the present invention is as follows:

[0006] The present invention provides an indoor measurement method for the scattering coefficient of a heavy metal solution per unit concentration direction, comprising:

[0007] S1: Set up the radiance measurement device;

[0008] S2: using the radiance measuring device to measure the reflected radiance of the standard plate, the composite reflected radiance of the standard plate and glass, the scattered radiance of pure water, and the scattered radiance of the heavy metal solution to be measured in sequence;

[0009] S3: Calculate the scattering coefficient of the heavy metal solution per unit concentration according to the reflected radiance of the standard plate, the composite reflected radiance of the standard plate and glass, the scattered radiance of pure water and the scattered radiance of the heavy metal solution to be measured.

[0010] Preferably, the radiance measurement device comprises a light source, a standard plate, a glass cylinder and a spectrometer probe;

[0011] The light source is arranged above the glass cylinder and emits incident light at an incident angle θ toward the standard plate or the glass cylinder;

[0012] The glass cylinder is arranged on the upper surface of the standard plate and is used to contain the sample to be tested;

[0013] The standard plate is used to directly reflect incident light or incident light transmitted through the glass cylinder;

[0014] The spectrometer probe is vertically arranged above the glass cylinder and is used to measure the radiance of the incident light reflected by the standard plate or the radiance of the scattered light of the incident light scattered by the sample to be measured.

[0015] Preferably, the specific method of step S2 is:

[0016] S2.1: The light source emits incident light at an incident angle θ to the standard plate, and the spectrometer probe measures the radiance of the incident light reflected by the standard plate, which is recorded as the radiance L reflected by the standard plate 0 ;

[0017] S2.2: Place a glass cylinder on the surface of the standard plate. The spectrometer probe measures the radiance of the incident light reflected by the standard plate through the glass cylinder, which is recorded as the composite reflected radiance of the standard plate and glass, Lb ;

[0018] S2.3: Add pure water to a height of H into the glass cylinder. The spectrometer probe measures the radiance of the scattered light of the incident light scattered by the pure water, which is recorded as the pure water scattered radiance L w ;

[0019] S2.4: Add a heavy metal compound reagent of weight M to be tested into pure water, stir evenly and let stand to form a heavy metal solution to be tested. The spectrometer probe measures the radiance of the scattered light of the incident light scattered by the heavy metal solution to be tested, which is recorded as the scattered radiance of the heavy metal solution to be tested L u .

[0020] The incident angle and irradiance of the incident light emitted by the light source remain unchanged in step S2.

[0021] Preferably, the specific method of step S3 is:

[0022] S3.1: Calculate the composite reflectivity of the standard plate-glass based on the reflected radiance of the standard plate and the composite reflected radiance of the standard plate-glass;

[0023] S3.2: Calculate the reflectivity of pure water off water based on the reflected radiance of the standard plate and the scattered radiance of pure water;

[0024] S3.3: Construct the radiation transmission equation of pure water based on the reflectivity of pure water off water and the composite reflectivity of the standard plate-glass, and calculate the scattering coefficient of the unit concentration direction of water molecules;

[0025] S3.4: Calculate the reflectivity of the heavy metal solution to be tested from water based on the reflected radiance of the standard plate and the scattered radiance of the heavy metal solution to be tested;

[0026] S3.5: Construct the radiation transmission equation of the heavy metal solution to be tested based on the water-leaving reflectivity of the heavy metal solution to be tested, the unit concentration directional scattering coefficient of water molecules and the standard plate-glass composite reflectivity, and calculate the unit concentration directional scattering coefficient of the heavy metal solution to be tested.

[0027] Preferably, in step S3.1, the specific method for calculating the composite reflectivity of the standard plate-glass is:

[0028] According to the isotropic properties of the Lambertian body:

[0029]

[0030]

[0031]

[0032] In the formula, R b Represents the composite reflectivity of the standard plate and glass, R0 Indicates the reflectivity of the standard plate, E 0 Represents the incident light irradiance.

[0033] Preferably, in step S3.2, the specific method for calculating the pure water off-water reflectivity is:

[0034]

[0035]

[0036]

[0037] In the formula, R w Represents the reflectivity of pure water.

[0038] Preferably, in step S3.3, the specific method for calculating the scattering coefficient of the unit concentration direction of water molecules is:

[0039] Construct the radiative transfer equation for pure water:

[0040]

[0041] Inversely solve the radiation transfer equation of pure water to obtain the scattering coefficient of water molecules per unit concentration:

[0042]

[0043] In the formula, ω w (θ) represents the scattering coefficient of water molecules per unit concentration direction, θ represents the scattering angle; k w represents the extinction coefficient of pure water, H represents the height of pure water, R w Represents the reflectivity of pure water off water, R b represents the composite reflectivity of the standard plate and glass; μ represents the observation coefficient, μ = secθ z +secθ v ,θ z represents the zenith angle of the incident light refracted by pure water, θ v Indicates the zenith angle of the spectrometer measurement direction, Θ = 180°- z .

[0044] Preferably, in step S3.4, the specific method for calculating the water-off reflectivity of the heavy metal solution to be measured is:

[0045]

[0046]

[0047]

[0048] In the formula, Ru Indicates the reflectivity of the heavy metal solution to be tested when it leaves water.

[0049] Preferably, in step S3.5, the specific method for calculating the scattering coefficient of the unit concentration direction of the heavy metal solution to be measured is:

[0050] Construct the radiation transfer equation of the heavy metal solution to be tested:

[0051]

[0052] Inversely solve the radiation transfer equation of the heavy metal solution to be measured and obtain the scattering coefficient of the unit concentration direction of the heavy metal solution to be measured:

[0053]

[0054] R b ,R w ,ω w (θ),R u Substituting into the above formula, we get:

[0055]

[0056] In the formula, ω u (Θ) represents the scattering coefficient of the unit concentration direction of the heavy metal solution to be measured, k u Indicates the extinction coefficient of the unit concentration of the heavy metal solution to be measured, D u Indicates the concentration of the heavy metal solution to be tested.

[0057] Among them, L 0 ,L b ,L w ,L u These are all known values ​​measured by the spectrometer probe. The reflectivity of the standard plate R 0 is a known value provided by the manufacturer; the zenith angle θ of the incident light refracted by pure water z Obtained from the measurement, the spectrometer probe is set vertically, and the zenith angle θ of the spectrometer measurement direction v =0°; extinction coefficient k of unit concentration of heavy metal solution to be measured u , the extinction coefficient of pure water k w , the height H of pure water and the concentration D of the heavy metal solution to be measured u All are known values.

[0058] Preferably, the scattering type is determined according to the wavelength of the incident light and the heavy metal particle size of the heavy metal solution to be measured; when the scattering type obeys the Rayleigh scattering type law, the scattering phase function is determined, and the scattering coefficient of the heavy metal solution to be measured is divided by the scattering phase function in the scattering direction to calculate the scattering coefficient of the heavy metal solution to be measured; when the scattering type obeys the Mie scattering or non-selective scattering type law, the mathematical form of the scattering phase function is usually uncertain; through the method of the present invention, the scattering coefficient of the heavy metal solution to be measured at different scattering angles is calculated, the scattering phase function is fitted, and then the scattering coefficient of the heavy metal solution to be measured is calculated.

[0059] Preferably, the heavy metal compound reagent to be detected includes any one of copper sulfate pentahydrate, potassium ferrocyanide, ferric sulfate, ferric chloride, ferric hydroxide, cadmium oxide, cadmium sulfide, cadmium chloride, lead sulfide, lead oxide, lead chromate, lead sulfate, and lead nitrate.

[0060] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0061] The present invention sets a radiance measuring device to measure the reflected radiance of a standard plate, the composite reflected radiance of a standard plate and glass, the scattered radiance of pure water and the scattered radiance of a heavy metal solution to be measured in sequence, and directly calculates the unit concentration directional scattering coefficient of the heavy metal solution to be measured based on the above accurately measured radiances; the present invention does not need to rely on a specific natural water body in the wild, and takes into account the influence of the reflected light at the bottom of the standard plate and glass composite structure, so as to realize the accurate measurement of the unit concentration directional scattering coefficient of the heavy metal solution in an indoor environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] Figure 1 This is a flow chart of the indoor measurement method of the directional scattering coefficient per unit concentration of a heavy metal solution described in Example 1.

[0063] Figure 2 This is a schematic structural diagram of the radiance measurement device described in Example 2.

[0064] Figure 3 Schematic diagram of the spectral curves of the four radiances described in Example 3.

[0065] Figure 4 It is a schematic diagram of the spectral curves of the extinction coefficient of pure water and the extinction coefficient of copper sulfate pentahydrate solution described in Example 3.

[0066] Figure 5 This is a schematic diagram of a spectral curve of the scattering coefficient per unit concentration direction of a copper sulfate pentahydrate solution in a continuous wavelength range when the scattering angle is 159° as described in Example 3.

[0067] In the figure, 1-light source, 2-standard plate, 3-glass cylinder, 4-spectrometer probe. DETAILED DESCRIPTION

[0068] The drawings are for illustrative purposes only and should not be construed as limiting the present patent;

[0069] In order to better illustrate the present embodiment, some parts in the drawings may be omitted, enlarged or reduced, and do not represent the size of the actual product;

[0070] It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0071] The technical solution of the present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0072] Example 1

[0073] This embodiment provides an indoor measurement method for the scattering coefficient of a heavy metal solution per unit concentration. Figure 1 As shown, including:

[0074] S1: Set up the radiance measurement device;

[0075] S2: using the radiance measuring device to measure the reflected radiance of the standard plate, the composite reflected radiance of the standard plate and glass, the scattered radiance of pure water, and the scattered radiance of the heavy metal solution to be measured in sequence;

[0076] S3: Calculate the scattering coefficient of the heavy metal solution per unit concentration according to the reflected radiance of the standard plate, the composite reflected radiance of the standard plate and glass, the scattered radiance of pure water and the scattered radiance of the heavy metal solution to be measured.

[0077] In the specific implementation process, this embodiment sets up a radiance measurement device to measure the reflected radiance of the standard plate, the reflected radiance of the standard plate-glass composite, the scattered radiance of pure water and the scattered radiance of the heavy metal solution to be measured in turn, and directly calculates the unit concentration directional scattering coefficient of the heavy metal solution to be measured based on the above accurately measured radiance; this embodiment does not need to rely on specific natural water bodies in the wild, and takes into account the influence of the reflected light at the bottom of the standard plate and the glass composite structure, and realizes the accurate measurement of the unit concentration directional scattering coefficient of the heavy metal solution in the indoor environment.

[0078] Example 2

[0079] This embodiment provides an indoor measurement method for the scattering coefficient of a heavy metal solution per unit concentration, comprising:

[0080] S1: Set up the radiance measurement device; Figure 2 As shown, the radiance measurement device includes a light source 1, a standard plate 2, a glass cylinder 3 and a spectrometer probe 4;

[0081] The light source 1 is disposed above the glass cylinder and emits incident light at an incident angle θ toward the standard plate 2 or the glass cylinder 3;

[0082] The glass cylinder 3 is arranged on the upper surface of the standard plate 2 and is used to contain the sample to be tested;

[0083] The standard plate 2 is used to directly reflect the incident light or the incident light passing through the glass cylinder 3;

[0084] The spectrometer probe 4 is vertically arranged above the glass cylinder 3 and is used to measure the radiance of the incident light reflected by the standard plate 2 or the radiance of the scattered light of the incident light scattered by the sample to be measured.

[0085] S2: using the radiance measuring device to measure the reflected radiance of the standard plate, the composite reflected radiance of the standard plate and glass, the scattered radiance of pure water and the scattered radiance of the heavy metal solution to be measured in sequence; the specific method is:

[0086] S2.1: Light source 1 emits incident light to standard plate 2 at an incident angle θ, and spectrometer probe 4 measures the radiance of the incident light reflected by standard plate 2, which is recorded as the radiance L reflected by the standard plate 0 ;

[0087] S2.2: Place a glass cylinder 3 on the upper surface of the standard plate 2. The spectrometer probe 4 measures the radiance of the incident light reflected by the standard plate 2 and passing through the glass cylinder 3, which is recorded as the composite reflected radiance of the standard plate-glass L b ;

[0088] S2.3: Add pure water to a height of H into the glass cylinder 3, and the spectrometer probe 4 measures the radiance of the scattered light of the incident light scattered by the pure water, which is recorded as the pure water scattered radiance L w ;

[0089] S2.4: Add a heavy metal compound reagent of weight M to be tested into pure water, stir evenly and let stand to form a heavy metal solution to be tested. The spectrometer probe 4 measures the radiance of the scattered light of the incident light scattered by the heavy metal solution to be tested, which is recorded as the scattered radiance of the heavy metal solution to be tested L u .

[0090] In this embodiment, the heavy metal compound reagent to be tested is any one of copper sulfate pentahydrate, potassium ferrocyanide, ferric sulfate, ferric chloride, ferric hydroxide, cadmium oxide, cadmium sulfide, cadmium chloride, lead sulfide, lead oxide, lead chromate, lead sulfate, and lead nitrate.

[0091] S3: Calculate the scattering coefficient of the heavy metal solution per unit concentration according to the reflected radiance of the standard plate, the composite reflected radiance of the standard plate and glass, the scattered radiance of pure water and the scattered radiance of the heavy metal solution to be measured; the specific method is:

[0092] S3.1: Calculate the composite reflectivity of the standard plate-glass based on the reflected radiance of the standard plate and the composite reflected radiance of the standard plate-glass. Specifically, based on the isotropic properties of the Lambertian body:

[0093]

[0094]

[0095]

[0096] In the formula, R b Represents the composite reflectivity of the standard plate and glass, R 0 Indicates the reflectivity of the standard plate, E 0 Represents the incident light irradiance.

[0097] S3.2: Calculate the reflectivity of pure water off water based on the reflected radiance of the standard plate and the scattered radiance of pure water. Specifically, based on the isotropic properties of the Lambertian body:

[0098]

[0099]

[0100]

[0101] In the formula, R w Represents the reflectivity of pure water.

[0102] S3.3: Based on the pure water off-water reflectivity and the standard plate-glass composite reflectivity, the radiation transmission equation of pure water is constructed to calculate the unit concentration directional scattering coefficient of water molecules; specifically:

[0103] Construct the radiative transfer equation for pure water:

[0104]

[0105] Inversely solve the radiation transfer equation of pure water to obtain the scattering coefficient of water molecules per unit concentration:

[0106]

[0107] In the formula, ω w (θ) represents the scattering coefficient of water molecules per unit concentration direction, θ represents the scattering angle; k w represents the extinction coefficient of pure water, H represents the height of pure water, R w Represents the reflectivity of pure water off water, R b represents the composite reflectivity of the standard plate and glass; μ represents the observation coefficient, μ = secθ z +secθ v ,θ zrepresents the zenith angle of the incident light refracted by pure water, θ v Indicates the zenith angle of the spectrometer measurement direction, θ = 180° - θ z .

[0108] S3.4: Calculate the reflectivity of the heavy metal solution to be tested from water based on the reflected radiance of the standard plate and the scattered radiance of the heavy metal solution to be tested; specifically, based on the isotropic properties of the Lambertian body:

[0109]

[0110]

[0111]

[0112] In the formula, R u Indicates the reflectivity of the heavy metal solution to be tested when it leaves water.

[0113] S3.5: Construct the radiation transmission equation of the heavy metal solution to be tested based on the reflectivity of the heavy metal solution off water, the scattering coefficient of the water molecule per unit concentration and the composite reflectivity of the standard plate-glass, and calculate the scattering coefficient of the heavy metal solution per unit concentration; specifically:

[0114] Construct the radiation transfer equation of the heavy metal solution to be tested:

[0115]

[0116] Inversely solve the radiation transfer equation of the heavy metal solution to be measured and obtain the scattering coefficient of the unit concentration direction of the heavy metal solution to be measured:

[0117]

[0118] R b ,R w ,ω w (θ),R u Substituting into the above formula, we get:

[0119]

[0120] In the formula, ω u (Θ) represents the scattering coefficient of the unit concentration direction of the heavy metal solution to be measured, k u Indicates the extinction coefficient of the unit concentration of the heavy metal solution to be measured, D u Indicates the concentration of the heavy metal solution to be tested.

[0121] Among them, L 0 ,L b ,L w ,L u These are all known values ​​measured by the spectrometer probe. The reflectivity of the standard plate R0 is a known value provided by the manufacturer; the zenith angle θ of the incident light refracted by pure water z Obtained from the measurement, the spectrometer probe is set vertically, and the zenith angle θ of the spectrometer measurement direction v =0°; extinction coefficient k of unit concentration of heavy metal solution to be measured u , the extinction coefficient of pure water k w , the height H of pure water and the concentration D of the heavy metal solution to be measured u All are known values, and the scattering coefficient ω of the unit concentration direction of the heavy metal solution to be measured at the scattering angle θ can be calculated u (Θ).

[0122] Example 3

[0123] This example uses copper sulfate pentahydrate as the heavy metal compound reagent to be measured to illustrate the indoor measurement method of the scattering coefficient of the unit concentration direction of the heavy metal solution provided in Example 2:

[0124] The spectrometer probe 4 is set vertically, and the zenith angle θ of the spectrometer measurement direction is v =0°; light source 1 emits incident light at an incident angle θ, and the wavelength of the incident light is λ; spectrometer probe 4 measures the reflected radiance L of the standard plate in turn 0 , Standard plate-glass composite reflection radiance L b After that, pure water with a height of H = 15 cm is added to the glass cylinder 3. The zenith angle θ of the incident light after refraction by the water surface is z =21°, then the scattering angle θ = 180°-21° = 159°, the observation coefficient μ = sec 21° + sec 0° ≈ 2.07, and the spectrometer probe 4 measures the scattered radiance L of pure water w ; Add copper sulfate pentahydrate to pure water, stir evenly and let stand to form a copper sulfate pentahydrate solution to be tested, concentration D u =2.06g / L, the spectrometer probe 4 measures the scattered radiance L of the copper sulfate pentahydrate solution to be tested u ; The spectrometer probe measures four types of radiance corresponding to the continuous wavelength range and draws them into a schematic diagram of the radiance spectrum curve, as shown in Figure 3 Shown

[0125] like Figure 4 The figure shows the spectral curves of the extinction coefficients of pure water and copper sulfate pentahydrate solution. The extinction coefficient k of pure water is determined in the figure according to the wavelength of the incident light λ. w and the extinction coefficient k of copper sulfate pentahydrate solution u ; Combined with the reflectivity R provided by the manufacturer of standard plate 2 0 , the unit concentration directional scattering coefficient ω of copper sulfate pentahydrate solution is calculated when the scattering angle is 159° u (159°);

[0126] like Figure 5 As shown, it is a schematic diagram of the spectral curve of the scattering coefficient of the unit concentration direction of the copper sulfate pentahydrate solution in the continuous wavelength range when the scattering angle is 159°; it can be seen from the figure that the scattering intensity is concentrated in the short-wave range, and the scattering coefficient is zero from the wavelength of about 600nm to the long-wave direction; Figure 5 The results in the figure are consistent with the Rayleigh scattering law. As the wavelength increases, the scattering effect decreases rapidly, which is consistent with the particle size level of copper ions formed when copper sulfate pentahydrate is dissolved in water.

[0127] Furthermore, the scattering phase function that obeys Rayleigh scattering is as follows:

[0128]

[0129] Then P u (159°)≈1.40; combined with the unit concentration directional scattering coefficient of copper sulfate pentahydrate solution ω u (159°), the scattering coefficient of copper sulfate pentahydrate solution can be calculated The defect that the scattering coefficient cannot be obtained through indoor tests is solved.

[0130] The same or similar reference numerals correspond to the same or similar components;

[0131] The terms used in the drawings to describe positional relationships are only used for illustrative purposes and should not be construed as limiting this patent;

[0132] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. An indoor measurement method for the scattering coefficient of a unit concentration direction of a heavy metal solution, characterized in that: include: S1: Set up the radiance measurement device; S2: using the radiance measuring device to measure the reflected radiance of the standard plate, the composite reflected radiance of the standard plate and glass, the scattered radiance of pure water, and the scattered radiance of the heavy metal solution to be measured in sequence; S3: Calculate the scattering coefficient of the heavy metal solution per unit concentration according to the reflected radiance of the standard plate, the composite reflected radiance of the standard plate and glass, the scattered radiance of pure water and the scattered radiance of the heavy metal solution to be measured. The specific method is: S3.1: Calculate the composite reflectivity of the standard plate-glass based on the reflected radiance of the standard plate and the composite reflected radiance of the standard plate-glass; S3.2: Calculate the reflectivity of pure water off water based on the reflected radiance of the standard plate and the scattered radiance of pure water; S3.3: Based on the pure water off-water reflectivity and the standard plate-glass composite reflectivity, the radiation transmission equation of pure water is constructed to calculate the unit concentration directional scattering coefficient of water molecules. The specific method is as follows: Construct the radiative transfer equation for pure water: Inversely solve the radiation transfer equation of pure water to obtain the scattering coefficient of water molecules per unit concentration: In the formula, ω w (θ) represents the scattering coefficient of water molecules per unit concentration direction, θ represents the scattering angle; k w represents the extinction coefficient of pure water, H represents the height of pure water, R w Represents the reflectivity of pure water off water, R b represents the composite reflectivity of the standard plate and glass; μ represents the observation coefficient, μ = secθ z +secθ v ,θ z represents the zenith angle of the incident light refracted by pure water, θ v Indicates the zenith angle of the spectrometer measurement direction; S3.4: Calculate the reflectivity of the heavy metal solution to be tested from water based on the reflected radiance of the standard plate and the scattered radiance of the heavy metal solution to be tested. The specific method is as follows: In the formula, R u represents the reflectivity of the heavy metal solution to be tested, L0 represents the reflected radiance of the standard plate, R0 represents the reflectivity of the standard plate, E0 represents the irradiance of the incident light, L u Indicates the scattered radiance of the heavy metal solution to be measured; S3.5: Construct the radiation transmission equation of the heavy metal solution to be tested based on the water-leaving reflectivity of the heavy metal solution to be tested, the unit concentration directional scattering coefficient of water molecules and the standard plate-glass composite reflectivity, and calculate the unit concentration directional scattering coefficient of the heavy metal solution to be tested.

2. The indoor measurement method of the scattering coefficient per unit concentration direction of a heavy metal solution according to claim 1, characterized in that: The radiance measurement device comprises a light source, a standard plate, a glass cylinder and a spectrometer probe; The light source is arranged above the glass cylinder and emits incident light at an incident angle θ toward the standard plate or the glass cylinder; The glass cylinder is arranged on the upper surface of the standard plate and is used to contain the sample to be tested; The standard plate is used to directly reflect incident light or incident light transmitted through the glass cylinder; The spectrometer probe is vertically arranged above the glass cylinder and is used to measure the radiance of the incident light reflected by the standard plate or the radiance of the scattered light of the incident light scattered by the sample to be measured.

3. The indoor measurement method of the scattering coefficient per unit concentration direction of a heavy metal solution according to claim 2, characterized in that: The specific method of step S2 is: S2.1: The light source emits incident light at an incident angle θ to the standard plate, and the spectrometer probe measures the radiance of the incident light reflected by the standard plate, which is recorded as the reflected radiance L0 of the standard plate; S2.2: Place a glass cylinder on the surface of the standard plate. The spectrometer probe measures the radiance of the incident light reflected by the standard plate through the glass cylinder, which is recorded as the composite reflected radiance of the standard plate and glass, L b ; S2.3: Add pure water to a height of H into the glass cylinder. The spectrometer probe measures the radiance of the scattered light of the incident light scattered by the pure water, which is recorded as the pure water scattered radiance L w ; S2.4: Add a heavy metal compound reagent of weight M to be tested into pure water, stir evenly and let stand to form a heavy metal solution to be tested. The spectrometer probe measures the radiance of the scattered light of the incident light scattered by the heavy metal solution to be tested, which is recorded as the scattered radiance of the heavy metal solution to be tested L u .

4. The indoor measurement method of the scattering coefficient per unit concentration direction of a heavy metal solution according to claim 3, characterized in that: In step S3.1, the specific method for calculating the composite reflectivity of the standard plate-glass is: In the formula, R b represents the composite reflectivity of standard plate-glass, R0 represents the reflectivity of standard plate, and E0 represents the irradiance of incident light.

5. The indoor measurement method of the scattering coefficient of unit concentration direction of heavy metal solution according to claim 4 is characterized in that: In step S3.2, the specific method for calculating the pure water off-water reflectivity is: In the formula, R w Represents the reflectivity of pure water.

6. The indoor measurement method of the scattering coefficient of unit concentration direction of heavy metal solution according to claim 5, characterized in that: In step S3.5, the specific method for calculating the scattering coefficient of the unit concentration direction of the heavy metal solution to be measured is: Construct the radiation transfer equation of the heavy metal solution to be tested: Inversely solve the radiation transfer equation of the heavy metal solution to be measured and obtain the scattering coefficient of the unit concentration direction of the heavy metal solution to be measured: R b ,R w ,ω w (θ),R u Substituting into the above formula, we get: In the formula, ω u (Θ) represents the scattering coefficient of the unit concentration direction of the heavy metal solution to be measured, k u Indicates the extinction coefficient of the unit concentration of the heavy metal solution to be measured, D u Indicates the concentration of the heavy metal solution to be tested.

7. The indoor measurement method of the scattering coefficient per unit concentration direction of a heavy metal solution according to claim 3, characterized in that: The heavy metal compound reagent to be tested includes any one of copper sulfate pentahydrate, potassium ferrocyanide, ferric sulfate, ferric chloride, ferric hydroxide, cadmium oxide, cadmium sulfide, cadmium chloride, lead sulfide, lead oxide, lead chromate, lead sulfate, and lead nitrate.

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