Infrared spectrum rapid quantitative detection and analysis method of total petroleum hydrocarbon in soil

Abstract

The application provides a method for rapid quantitative detection and analysis of total petroleum hydrocarbon in soil by infrared spectrum, and relates to the technical field of environmental detection, and comprises the following steps: obtaining infrared spectrum data of a non-characteristic absorption interval, a saturated hydrocarbon characteristic absorption interval and an aromatic hydrocarbon characteristic absorption interval of target soil, and carrying out absorption degree conversion and pretreatment; calculating a soil matrix scattering correction factor based on a background absorption degree value of the non-characteristic absorption interval, and calculating a hydrocarbon structure correction coefficient based on a ratio of absorption degree values of the saturated hydrocarbon characteristic absorption interval and the aromatic hydrocarbon characteristic absorption interval; calculating a dynamic deviation judgment threshold value based on the correction factor and the correction coefficient; calculating a comprehensive relative deviation value of absorption degrees of the saturated hydrocarbon characteristic absorption interval and the aromatic hydrocarbon characteristic absorption interval, comparing the comprehensive relative deviation value with the dynamic deviation judgment threshold value to judge the effectiveness of the spectrum data, and executing corresponding disposal instructions according to the judgment result. Through double correction and self-adaptive quality control, the accuracy and reliability of infrared spectrum detection of total petroleum hydrocarbon in soil are effectively improved.

Description

Technical Field

[0001] This invention relates to the field of environmental monitoring technology, specifically to a rapid quantitative detection and analysis method for total petroleum hydrocarbons in soil using infrared spectroscopy. Background Technology

[0002] Total petroleum hydrocarbons (TPH) in soil are a core indicator for evaluating the degree of soil petroleum pollution. Accurate and rapid determination of TPH is crucial for risk assessment of contaminated sites, evaluation of remediation effectiveness, and environmental emergency monitoring. Infrared spectroscopy, due to its advantages of simple operation, rapid detection, and no need for complex sample pretreatment, has been widely used for rapid on-site screening of TPH in soil. In actual testing, the intensity of the infrared reflectance spectrum of soil samples is not only affected by the petroleum hydrocarbon content but also strongly depends on the physical properties of the soil matrix—including soil particle size, mineral composition, organic matter content, and compaction. These factors affect the scattering background of the reflectance spectrum, thus causing nonlinear interference to the true intensity of characteristic absorption peaks. Furthermore, the relative proportions of saturated hydrocarbons and aromatic hydrocarbons in petroleum hydrocarbons from different pollution sources vary significantly, and the hydrocarbon structure also changes significantly during environmental aging processes such as natural weathering and biodegradation. This leads to significant differences in the infrared response of different TPH samples with the same mass concentration within the characteristic absorption range.

[0003] In the prior art, patent CN121207924A discloses a rapid detection method for petroleum hydrocarbons in soil based on visible-near-infrared spectroscopy. This technique includes: preparing standard samples with a concentration gradient of 0~3000 mg / kg to establish a spectral database; preprocessing spectral data using Savitzky-Golay filtering and standard normal variable transformation; optimizing characteristic wavelengths using a competitive adaptive reweighted sampling algorithm and constructing a partial least squares regression quantitative model; and determining the CARS algorithm as having the best performance by comparing three feature selection methods: full spectrum, BOSS, and CARS.

[0004] However, the aforementioned existing technologies do not fully consider the physical scattering interference of soil matrix differences on the intensity of reflected spectra, nor do they establish corresponding chemical structure compensation mechanisms for the fluctuations in the ratio of saturated hydrocarbons to aromatic hydrocarbons in petroleum hydrocarbons from different sources. This results in limited applicability of their quantitative correction models under different types of soil and different oil pollution scenarios. At the same time, the scheme lacks dynamic judgment and quality control of the validity of spectral data, and cannot identify abnormal data caused by sudden changes in sample matrix or fluctuations in measurement conditions in real time during the detection process. This makes it difficult to effectively guarantee the reliability and robustness of the final quantitative results.

[0005] The information disclosed in the background section is only intended to enhance the understanding of the background of this disclosure, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0006] The purpose of this invention is to provide a rapid quantitative detection and analysis method for total petroleum hydrocarbons in soil using infrared spectroscopy, thereby addressing the problems mentioned in the background section. This invention constructs a multi-dimensional infrared spectral acquisition system covering non-characteristic absorption regions, saturated hydrocarbon characteristic absorption regions, and aromatic hydrocarbon characteristic absorption regions. It introduces a dual correction mechanism consisting of a soil matrix scattering correction factor and a hydrocarbon structure correction coefficient to eliminate physical interference caused by soil texture and chemical composition deviations due to oil source and weathering degradation. Simultaneously, a dynamic deviation judgment threshold is calculated based on the coupling result of the two correction factors, and compared in real time with the comprehensive relative deviation value of absorbance to determine the validity of the spectral data, thus constructing an adaptive quality control closed loop. This improves the accuracy and sample universality of the detection method.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] Rapid quantitative detection and analysis method of total petroleum hydrocarbons in soil using infrared spectroscopy:

[0009] S1: Acquire infrared spectral data of the target soil, including reflectance spectral intensity data of non-characteristic absorption regions, reflectance spectral intensity data of saturated hydrocarbon characteristic absorption regions, and reflectance spectral intensity data of aromatic hydrocarbon characteristic absorption regions. Perform absorbance conversion on the acquired infrared spectral data to obtain background absorbance values ​​of non-characteristic absorption regions, absorbance values ​​of saturated hydrocarbon characteristic absorption regions, and absorbance values ​​of aromatic hydrocarbon characteristic absorption regions. Preprocess the background absorbance values ​​of non-characteristic absorption regions, absorbance values ​​of saturated hydrocarbon characteristic absorption regions, and absorbance values ​​of aromatic hydrocarbon characteristic absorption regions.

[0010] S2: Based on the background absorbance values ​​of the non-characteristic absorption range after preprocessing, calculate the soil matrix scattering correction factor, and based on the absorbance values ​​of the characteristic absorption range of saturated hydrocarbons and the characteristic absorption range of aromatic hydrocarbons after preprocessing, calculate the hydrocarbon structure correction coefficient.

[0011] S3: Calculate the dynamic deviation judgment threshold based on the soil matrix scattering correction factor and hydrocarbon structure correction coefficient;

[0012] S4: Calculate the comprehensive relative deviation of absorbance based on the absorbance values ​​of the pre-processed saturated hydrocarbon characteristic absorption range and the aromatic hydrocarbon characteristic absorption range. Compare the comprehensive relative deviation of absorbance with the dynamic deviation judgment threshold. Determine whether the acquired infrared spectral data is valid based on the comparison result, and execute the corresponding disposal instructions based on the judgment result.

[0013] Furthermore, the method for performing absorbance conversion on the acquired infrared spectral data is as follows:

[0014] The reflectance spectral intensity data of non-characteristic absorption regions, saturated hydrocarbon characteristic absorption regions, and aromatic hydrocarbon characteristic absorption regions are each reciprocalized, and their logarithmic values ​​(base 10) are calculated to obtain the background absorbance value of the non-characteristic absorption region, the initial absorbance value of the saturated hydrocarbon characteristic absorption region, and the initial absorbance value of the aromatic hydrocarbon characteristic absorption region. The background absorbance value of the non-characteristic absorption region is used as a baseline reference value. The initial absorbance values ​​of the saturated hydrocarbon characteristic absorption region and the aromatic hydrocarbon characteristic absorption region are subtracted from the baseline reference value to obtain the absorbance values ​​of the saturated hydrocarbon characteristic absorption region and the aromatic hydrocarbon characteristic absorption region, respectively.

[0015] Furthermore, the method for preprocessing the background absorbance values ​​of non-characteristic absorption regions, the absorbance values ​​of saturated hydrocarbon characteristic absorption regions, and the absorbance values ​​of aromatic hydrocarbon characteristic absorption regions is as follows:

[0016] The convolution smoothing method is used to smooth the background absorbance values ​​of non-characteristic absorption regions, the absorbance values ​​of saturated hydrocarbon characteristic absorption regions, and the absorbance values ​​of aromatic hydrocarbon characteristic absorption regions, respectively.

[0017] Furthermore, the formula used to calculate the soil matrix scattering correction factor is as follows:

[0018]

[0019] in, Soil matrix scattering correction factor;

[0020] This represents the background absorbance value of the non-feature absorption region after preprocessing.

[0021] The baseline background absorbance value is the preset non-feature absorption range;

[0022] The preset scattering sensitivity coefficient, and >0.

[0023] Furthermore, the formula used to calculate the hydrocarbon structure correction factor is as follows:

[0024]

[0025] in, For hydrocarbon structure correction coefficients;

[0026] This represents the ratio of the absorbance value of the characteristic absorption range of pretreated saturated hydrocarbons to the absorbance value of the characteristic absorption range of pretreated aromatic hydrocarbons. The calculation formula is: ,in, The absorbance values ​​are the characteristic absorption range of the pretreated saturated hydrocarbons. This represents the absorbance value of the characteristic absorption range of aromatic hydrocarbons after pretreatment.

[0027] The baseline peak ratio of the preset standard TPH components;

[0028] and These are the preset positive compensation strength coefficient and negative compensation strength coefficient, respectively;

[0029] This is the preset lower limit value of the hydrocarbon structure correction coefficient.

[0030] Furthermore, the preset lower limit of the hydrocarbon structure correction coefficient is determined through the following calibration steps:

[0031] N sets of reference soil samples were obtained. Under infrared spectroscopy detection conditions, M repeated measurements were performed on each set of reference soil samples. For each measurement, a parameter was set. The initial value is 1, and the hydrocarbon structure correction coefficients corresponding to each measurement are calculated to obtain... Each hydrocarbon structure correction factor is taken as follows: The lower quartiles of the hydrocarbon structure correction coefficients are used as the lower limits of the hydrocarbon structure correction coefficients, where N and M are preset positive integers, and N≥3 and M≥3.

[0032] Furthermore, the formula used to calculate the dynamic deviation judgment threshold is as follows:

[0033]

[0034] in, The threshold for determining dynamic deviation;

[0035] This is the preset benchmark deviation threshold.

[0036] Furthermore, the formula used to calculate the comprehensive relative deviation value of absorbance is as follows:

[0037]

[0038] in, This represents the overall relative deviation value of absorbance.

[0039] The baseline absorbance value for the pre-defined characteristic absorption range of saturated hydrocarbons;

[0040] The baseline absorbance value for the pre-defined characteristic absorption range of aromatic hydrocarbons;

[0041] , These are the preset alkane weighting coefficients and preset aromatic weighting coefficients, respectively, and they satisfy... , >0, >0.

[0042] Furthermore, the determination logic for whether the acquired infrared spectral data is valid is as follows:

[0043] when ≤ When the infrared spectral data is obtained, it is determined to be valid;

[0044] when > If this occurs, the acquired infrared spectral data is deemed invalid.

[0045] Furthermore, the execution logic for the corresponding processing instruction is as follows:

[0046] When the acquired infrared spectral data is determined to be valid, the absorbance values ​​of the preprocessed saturated hydrocarbon characteristic absorption range and the aromatic hydrocarbon characteristic absorption range are input into the preset quantitative correction model to calculate the total petroleum hydrocarbon content in the target soil and output as the final detection result.

[0047] When the acquired infrared spectral data is determined to be invalid, the currently acquired infrared spectral data is discarded, and a prompt to reacquire the data is triggered.

[0048] Compared with the prior art, the beneficial effects of the present invention are:

[0049] This invention constructs a multi-dimensional infrared spectral data acquisition and processing system encompassing non-characteristic absorption regions, saturated hydrocarbon characteristic absorption regions, and aromatic hydrocarbon characteristic absorption regions. Based on this, it innovatively introduces a dual correction mechanism of soil matrix scattering correction factor and hydrocarbon structure correction coefficient. The soil matrix scattering correction factor, calculated based on the background absorbance value of the non-characteristic absorption region, effectively eliminates light scattering interference caused by differences in physical texture such as soil particle size and compaction. The hydrocarbon structure correction coefficient, adaptively adjusted according to the dynamic ratio of the characteristic absorption peaks of saturated hydrocarbons and aromatic hydrocarbons, corrects for the influence of differences in hydrocarbon component structure caused by different oil sources and environmental weathering and degradation on quantitative results. The synergistic effect of these two mechanisms enhances the anti-interference capability and sample universality of the detection method from both physical interference and chemical composition deviation dimensions. Simultaneously, a dynamic deviation judgment threshold is calculated based on the coupling result of the two correction factors, and this threshold is compared in real time with the comprehensive relative deviation value of absorbance to determine the validity of the spectral data. This constructs an adaptive quality control closed loop, overcoming the quantitative deviation problem caused by large differences in soil background and the complex and variable composition of petroleum hydrocarbons in traditional infrared spectroscopy, ensuring the accuracy and reliability of the detection results. Attached Figure Description

[0050] Figure 1 This is a schematic diagram of the overall process for a rapid quantitative detection and analysis method of total petroleum hydrocarbons in soil using infrared spectroscopy. Detailed Implementation

[0051] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0052] It should be noted that, unless otherwise defined, the technical or scientific terms used in this invention should have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms "first," "second," and similar terms used in this invention do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0053] Example:

[0054] Please see Figure 1 The present invention provides a technical solution:

[0055] Rapid quantitative detection and analysis method of total petroleum hydrocarbons in soil using infrared spectroscopy:

[0056] S1: Acquire infrared spectral data of the target soil. This infrared spectral data includes reflectance intensity data in the non-characteristic absorption region, reflectance intensity data in the saturated hydrocarbon characteristic absorption region, and reflectance intensity data in the aromatic hydrocarbon characteristic absorption region. The non-characteristic absorption region refers to the band range of characteristic absorption peaks of petroleum hydrocarbon components that are unidentifiable due to continuous scattering of infrared radiation by the soil matrix itself. The reflectance intensity in this region mainly reflects the comprehensive influence of physical properties such as soil particle size, surface morphology, and compaction on the optical path, and serves as the basic reference for subsequent correction of the soil matrix effect. The saturated hydrocarbon characteristic absorption region corresponds to the carbon content in saturated hydrocarbon molecules. The characteristic absorption band generated by hydrogen bond stretching vibrations shows a regular change in reflection intensity with the saturated hydrocarbon content. The characteristic absorption range of aromatic hydrocarbons corresponds to the characteristic absorption bands induced by the aromatic ring skeleton vibration and hydrocarbon bending vibration. The reflection intensity of these bands is closely related to the concentration of aromatic hydrocarbon components. The acquired infrared spectral data is converted to obtain the background absorbance values ​​of the non-characteristic absorption range, the absorbance values ​​of the saturated hydrocarbon characteristic absorption range, and the absorbance values ​​of the aromatic hydrocarbon characteristic absorption range. The background absorbance values ​​of the non-characteristic absorption range, the absorbance values ​​of the saturated hydrocarbon characteristic absorption range, and the absorbance values ​​of the aromatic hydrocarbon characteristic absorption range are then preprocessed.

[0057] The method used to perform absorbance conversion on the acquired infrared spectral data is as follows:

[0058] The reflectance spectral intensity data of non-characteristic absorption regions, saturated hydrocarbon characteristic absorption regions, and aromatic hydrocarbon characteristic absorption regions were reciprocally divided, and then logarithmic values ​​to the base 10 were calculated to obtain the background absorbance values ​​of the non-characteristic absorption regions, the initial absorbance values ​​of the saturated hydrocarbon characteristic absorption regions, and the initial absorbance values ​​of the aromatic hydrocarbon characteristic absorption regions. The absorbance values ​​corresponding to the non-characteristic absorption regions were defined as the baseline reference values ​​of the soil matrix under the measurement conditions. These values ​​reflect the overall attenuation effect of soil physical conditions (such as particle packing morphology, surface roughness, and compaction) on the reflection process, rather than the molecular vibrational absorption originating from specific chemical components. The saturated hydrocarbon... The initial absorbance values ​​of the characteristic absorption range and the initial absorbance values ​​of the aromatic hydrocarbon characteristic absorption range are respectively subtracted from the baseline reference value. The core purpose of this difference calculation is to remove the background component contributed by non-specific physical scattering from the total absorption signal of the characteristic range, thereby extracting the net absorbance value that is only related to the vibrational absorption of the functional groups of the target hydrocarbon. After the above baseline correction, the absorbance values ​​of the saturated hydrocarbon characteristic absorption range and the aromatic hydrocarbon characteristic absorption range have effectively eliminated the baseline offset effect caused by the physical differences of the soil matrix in the same measurement, so that the subsequent absorbance values ​​can more purely reflect the actual content and relative proportion of saturated hydrocarbon and aromatic hydrocarbon components in petroleum hydrocarbons.

[0059] The method for preprocessing the background absorbance values ​​of non-characteristic absorption regions, the absorbance values ​​of saturated hydrocarbon characteristic absorption regions, and the absorbance values ​​of aromatic hydrocarbon characteristic absorption regions is as follows:

[0060] The Savitzky-Golay convolution smoothing method was employed to smooth the background absorbance values ​​in the non-characteristic absorption region, the absorbance values ​​in the saturated hydrocarbon characteristic absorption region, and the absorbance values ​​in the aromatic hydrocarbon characteristic absorption region. The core purpose of this smoothing is to effectively suppress high-frequency random fluctuations caused by non-target factors such as random noise, environmental disturbances, or detector response fluctuations during measurement, without altering the overall trend of each absorbance sequence, thereby improving the signal-to-noise ratio and stability of the data. Specifically, smoothing was performed independently for each of the three sets of absorbance data, fully preserving the characteristic shape of each set. For the background absorbance values ​​in the non-characteristic absorption region, smoothing more accurately reflects the gradual change in soil matrix scattering background with wavenumber or measurement conditions, avoiding interference from local spikes in subsequent matrix correction calculations. For the absorbance values ​​in the saturated hydrocarbon characteristic absorption region, smoothing sharpens the peak profile generated by C-H bond vibrations within this region, making the peak height and area more representative. For the absorbance values ​​in the aromatic hydrocarbon characteristic absorption region, smoothing helps stabilize the aromatic hydrocarbon characteristic signal and reduces fluctuations introduced by excessive noise when the absorption intensity is weak.

[0061] S2: Based on the background absorbance values ​​of the non-characteristic absorption range after pretreatment, a soil matrix scattering correction factor is calculated. This soil matrix scattering correction factor reflects the degree of deviation of the target soil relative to the reference soil in the background absorbance values ​​of the non-characteristic absorption range. This deviation is caused by the light scattering effect resulting from differences in physical properties such as soil particle size, mineral composition, organic matter content, and compaction. Based on the absorbance values ​​of the characteristic absorption range of saturated hydrocarbons and the characteristic absorption range of aromatic hydrocarbons after pretreatment, a hydrocarbon structure correction coefficient is calculated. This hydrocarbon structure correction coefficient reflects the degree to which the relative ratio of saturated hydrocarbons to aromatic hydrocarbons in the target soil deviates from the reference peak ratio of standard TPH components. This deviation is caused by differences in oil sources and changes in hydrocarbon composition during environmental aging processes such as natural weathering and biodegradation.

[0062] The formula used to calculate the soil matrix scattering correction factor is as follows:

[0063]

[0064] in, Soil matrix scattering correction factor;

[0065] This represents the background absorbance value of the non-feature absorption region after preprocessing.

[0066] The baseline background absorbance value is the preset non-feature absorption range;

[0067] The preset scattering sensitivity coefficient, and >0;

[0068] When the background absorbance value in the non-characteristic absorption region Equal to the background absorbance value of the reference soil in the non-characteristic absorption range hour, This indicates that matrix scattering correction is not required; when the background absorbance value in the non-characteristic absorption region... Background absorbance values ​​greater than those of reference soil in the non-characteristic absorption range This indicates that the background scattering of the target soil is stronger than that of the reference soil. If the value is greater than 1, the dynamic deviation judgment threshold is increased accordingly to allow for reasonable fluctuations caused by the broadening of characteristic absorption peaks or baseline rise due to enhanced scattering; conversely, when the background absorbance value in the non-characteristic absorption region is lowered... The background absorbance value of the reference soil in the non-characteristic absorption range is less than that of the reference soil. When this occurs, it indicates that the background scattering from the target soil is relatively weak. <1, the dynamic deviation judgment threshold is reduced accordingly, thereby enabling stricter quality control under low background interference conditions and improving judgment sensitivity.

[0069] The formula used to calculate the hydrocarbon structure correction factor is as follows:

[0070]

[0071] in, For hydrocarbon structure correction coefficients;

[0072] This represents the ratio of the absorbance value of the characteristic absorption range of pretreated saturated hydrocarbons to the absorbance value of the characteristic absorption range of pretreated aromatic hydrocarbons. The calculation formula is ,in, The absorbance values ​​are the characteristic absorption range of the pretreated saturated hydrocarbons. This represents the absorbance value of the characteristic absorption range of aromatic hydrocarbons after pretreatment.

[0073] The baseline peak ratio of the preset standard TPH components;

[0074] and These are the preset positive compensation strength coefficient and negative compensation strength coefficient, respectively;

[0075] This is the preset lower limit value for hydrocarbon structure correction coefficients;

[0076] when > When the ratio of saturated hydrocarbons to aromatic hydrocarbons in the target soil is higher than that of standard oil, it indicates that the sample may be rich in light alkane components or that aromatic hydrocarbons have been relatively reduced due to volatilization and degradation. The fact that the coefficient of hydrocarbon structure correction increases rapidly with the increase of relative deviation in a square form means that the tolerance range is amplified when calculating the dynamic deviation judgment threshold in the subsequent calculation, so as to compensate for the characteristic absorption enhancement effect caused by the excess of saturated hydrocarbons.

[0077] when ≤ When the ratio of saturated hydrocarbons to aromatic hydrocarbons in the target soil is lower than that of the standard oil benchmark, it indicates that the sample may be dominated by heavy oil components, or that saturated hydrocarbons have been preferentially lost due to aging processes such as evaporation, biodegradation, etc., resulting in a relative enrichment of aromatic hydrocarbon components in the residual petroleum hydrocarbons. It decreases linearly with increasing ratio deviation and is constrained to a preset lower limit. The reason for adopting linear attenuation is that the absorption bands of aromatic ring skeleton vibrations in aromatic hydrocarbons typically exhibit stable linear concentration response characteristics, unlike the nonlinear enhancement effect caused by intermolecular forces in the high concentration range of saturated hydrocarbons. Therefore, linear attenuation is more consistent with its physical response mechanism and can appropriately narrow the allowable deviation range to suppress the potential bias risk of aromatic enrichment on quantitative results; at the same time As the lower limit of the hydrocarbon structure correction coefficient, it ensures that the correction range will not excessively compress the dynamic deviation judgment threshold under extreme weathering or heavy oil pollution conditions, thereby maintaining the basic sensitivity and robustness of quality control.

[0078] The preset lower limit of the hydrocarbon structure correction coefficient is determined through the following calibration steps:

[0079] N sets of reference soil samples were obtained. Here, "reference" refers to a set of samples that are clearly representative and measured under consistent conditions, used to establish the statistical reference baseline for the correction coefficient. These samples serve as a reference system for method parameter calibration, providing a statistical benchmark for the correction coefficient of subsequent measured samples, rather than being limited to a specific soil type. To ensure that the determined lower limit values ​​have good applicability and robustness in different actual testing scenarios, the selected N sets of reference soil samples should systematically cover the main variation ranges of key factors such as soil texture, organic matter content, and mineral composition, encompassing different texture types such as sandy, loamy, and clayey, as well as low, medium, and high organic matter content and typical mineral assemblage characteristics. Under infrared spectroscopy detection conditions, each set of reference soil samples was measured M times repeatedly. For each measurement, a [specific measurement method] was set. The initial value is 1, and the hydrocarbon structure correction coefficients corresponding to each measurement are calculated to obtain... Each hydrocarbon structure correction factor is taken as follows: The lower quartiles of the hydrocarbon structure correction coefficients are used as the lower limits of the hydrocarbon structure correction coefficients, where N and M are preset positive integers, and N≥3 and M≥3.

[0080] S3: Based on the soil matrix scattering correction factor and hydrocarbon structure correction coefficient, the dynamic deviation judgment threshold is calculated. The dynamic deviation judgment threshold reflects the dynamic adjustment value of the allowable fluctuation range of spectral absorbance under the dual coupling effect of soil matrix physical scattering effect and the difference in chemical composition of petroleum hydrocarbons.

[0081] The formula used to calculate the dynamic deviation threshold is as follows:

[0082]

[0083] in, The threshold for determining dynamic deviation;

[0084] This is the preset baseline deviation threshold;

[0085] when When it increases, The increase in threshold value implies that in samples with relatively high saturated hydrocarbon content, the dynamic deviation threshold is appropriately relaxed to accommodate the increase in the overall relative deviation of absorbance caused by the enhanced characteristic absorption effect due to excess saturated hydrocarbons. This prevents normal measurement data from being incorrectly rejected due to an overly strict threshold when the hydrocarbon structure deviates significantly from the standard state. When decreasing, The corresponding reduction means that in samples with relatively rich aromatic hydrocarbons, the allowable deviation range is moderately narrowed to suppress measurement fluctuations that may be introduced by differences in the stability of characteristic absorption signals when aromatic components dominate.

[0086] The method described in this invention is not only applicable to conventional contaminated site assessment, but its core logic of dual correction and adaptive quality control also provides a referable technical path for eliminating complex matrix interference in the detection of new materials (such as the assessment of the adsorption efficiency of new adsorbent materials for petroleum hydrocarbons).

[0087] S4: Calculate the comprehensive relative deviation value of absorbance based on the absorbance values ​​of the characteristic absorption range of saturated hydrocarbons and aromatic hydrocarbons after pretreatment. This comprehensive relative deviation value comprehensively characterizes the degree of deviation of the characteristic absorption intensity of saturated hydrocarbons and aromatic hydrocarbons from their respective preset benchmark values. It is then weighted according to the preset weights of alkanes and aromatics to reflect the overall fluctuation of the two hydrocarbon components in the absorption response. The comprehensive relative deviation value of absorbance is compared with the dynamic deviation judgment threshold. The validity of the obtained infrared spectral data is determined based on the comparison result, and the corresponding processing instructions are executed based on the judgment result.

[0088] The formula used to calculate the overall relative deviation of absorbance is as follows:

[0089]

[0090] in, This represents the overall relative deviation value of absorbance.

[0091] The baseline absorbance value for the pre-defined characteristic absorption range of saturated hydrocarbons;

[0092] The baseline absorbance value for the pre-defined characteristic absorption range of aromatic hydrocarbons;

[0093] , These are the preset alkane weighting coefficients and preset aromatic weighting coefficients, respectively, and they satisfy... , >0, >0;

[0094] The value represents the relative deviation of the characteristic absorption intensity of saturated hydrocarbons from its reference value. The larger the value, the more significant the infrared response of the saturated hydrocarbon components in the current sample is compared with the standard state. This may be due to the actual increase in the concentration of saturated hydrocarbons in the sample, or it may be due to the enhanced scattering of the soil matrix or the enhanced nonlinear response caused by the interaction between saturated hydrocarbon molecules. This value characterizes the relative deviation of the characteristic absorption intensity of aromatic hydrocarbons from their reference value. A larger value indicates a greater deviation of the infrared response of the aromatic hydrocarbon component from the reference value; the overall relative deviation value of absorbance... The larger the value, the more significant the deviation of the current spectral data from the standard reference state. This deviation may be caused by the actual change in the concentration of petroleum hydrocarbons in the sample, or it may be induced by non-target factors such as matrix interference, sample inhomogeneity, and instrument drift during the measurement process.

[0095] The determination logic for whether the acquired infrared spectral data is valid is as follows:

[0096] when ≤ This indicates that the absorption characteristics of saturated and aromatic hydrocarbons reflected in the current infrared spectral data are still within an acceptable range of normal fluctuations after deducting the fluctuations in soil physical background and differences in hydrocarbon chemical composition. The infrared spectral data obtained is deemed valid, meaning that the effective chemical information in the spectral signal has not been obscured by abnormal interference and can be used for subsequent quantitative calculations.

[0097] when > If the current spectral response deviates from the baseline state beyond the allowable deviation limit determined by matrix scattering and hydrocarbon structure variation under the detection system, it means that there may be sample inhomogeneity, background drift or other uncontrollable disturbances during the measurement process. In this case, the spectral data cannot truly reflect the actual content of petroleum hydrocarbons in the target soil, and the obtained infrared spectral data is deemed invalid.

[0098] The execution logic for the corresponding processing instruction is as follows:

[0099] When the acquired infrared spectral data is deemed valid, the absorbance values ​​of the preprocessed saturated hydrocarbon characteristic absorption range and the aromatic hydrocarbon characteristic absorption range are input into a preset quantitative correction model. This quantitative correction model is pre-established based on the statistical correlation between the infrared spectral response of a known concentration standard sample and the corresponding total petroleum hydrocarbon content. It can comprehensively analyze the contribution weight of saturated hydrocarbons and aromatic hydrocarbons to the total petroleum hydrocarbon content based on the absorbance values ​​of each in the characteristic absorption range, and then calculate the total petroleum hydrocarbon content in the target soil, which is then output as the final detection result.

[0100] The establishment and verification process of this quantitative calibration model strictly followed the standards of chemometrics, ensuring the metrological traceability of the conversion process from spectral signals to concentration values;

[0101] When the acquired infrared spectral data is determined to be invalid, the currently acquired infrared spectral data is discarded, and a reacquisition prompt is triggered to remind the operator that the current measurement result is unreliable and that the measurement conditions need to be adjusted or the sample needs to be re-prepared before acquiring the spectrum again, until valid data is obtained.

[0102] The above formulas are all dimensionless calculations. The formulas are derived from software simulations using a large amount of data to obtain the most recent real-world results. The preset parameters in the formulas are set by those skilled in the art according to the actual situation.

[0103] The above embodiments can be implemented, in whole or in part, by software, hardware, firmware, or any other combination thereof. When implemented in software, the above embodiments can be implemented, in whole or in part, as a computer program product. Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented by electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution.

[0104] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment, depending on actual needs.

[0105] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application.

Claims

1. A rapid quantitative detection and analysis method for total petroleum hydrocarbons in soil using infrared spectroscopy, characterized by: S1: Acquire infrared spectral data of the target soil, including reflectance spectral intensity data of non-characteristic absorption regions, reflectance spectral intensity data of saturated hydrocarbon characteristic absorption regions, and reflectance spectral intensity data of aromatic hydrocarbon characteristic absorption regions. Perform absorbance conversion on the acquired infrared spectral data to obtain background absorbance values ​​of non-characteristic absorption regions, absorbance values ​​of saturated hydrocarbon characteristic absorption regions, and absorbance values ​​of aromatic hydrocarbon characteristic absorption regions. Preprocess the background absorbance values ​​of non-characteristic absorption regions, absorbance values ​​of saturated hydrocarbon characteristic absorption regions, and absorbance values ​​of aromatic hydrocarbon characteristic absorption regions. S2: Based on the background absorbance values ​​of the non-characteristic absorption range after preprocessing, calculate the soil matrix scattering correction factor, and based on the absorbance values ​​of the characteristic absorption range of saturated hydrocarbons and the characteristic absorption range of aromatic hydrocarbons after preprocessing, calculate the hydrocarbon structure correction coefficient. S3: Calculate the dynamic deviation judgment threshold based on the soil matrix scattering correction factor and hydrocarbon structure correction coefficient; S4: Calculate the comprehensive relative deviation of absorbance based on the absorbance values ​​of the pre-processed saturated hydrocarbon characteristic absorption range and the aromatic hydrocarbon characteristic absorption range. Compare the comprehensive relative deviation of absorbance with the dynamic deviation judgment threshold. Determine whether the acquired infrared spectral data is valid based on the comparison result, and execute the corresponding disposal instructions based on the judgment result.

2. The rapid quantitative detection and analysis method for total petroleum hydrocarbons in soil using infrared spectroscopy according to claim 1, characterized in that: The method used to perform absorbance conversion on the acquired infrared spectral data is as follows: The reflectance spectral intensity data of non-characteristic absorption regions, saturated hydrocarbon characteristic absorption regions, and aromatic hydrocarbon characteristic absorption regions are each reciprocalized, and their logarithmic values ​​(base 10) are calculated to obtain the background absorbance value of the non-characteristic absorption region, the initial absorbance value of the saturated hydrocarbon characteristic absorption region, and the initial absorbance value of the aromatic hydrocarbon characteristic absorption region. The background absorbance value of the non-characteristic absorption region is used as a baseline reference value. The initial absorbance values ​​of the saturated hydrocarbon characteristic absorption region and the aromatic hydrocarbon characteristic absorption region are subtracted from the baseline reference value to obtain the absorbance values ​​of the saturated hydrocarbon characteristic absorption region and the aromatic hydrocarbon characteristic absorption region, respectively.

3. The rapid quantitative detection and analysis method for total petroleum hydrocarbons in soil using infrared spectroscopy according to claim 2, characterized in that: The method for preprocessing the background absorbance values ​​of non-characteristic absorption regions, the absorbance values ​​of saturated hydrocarbon characteristic absorption regions, and the absorbance values ​​of aromatic hydrocarbon characteristic absorption regions is as follows: The convolution smoothing method is used to smooth the background absorbance values ​​of non-characteristic absorption regions, the absorbance values ​​of saturated hydrocarbon characteristic absorption regions, and the absorbance values ​​of aromatic hydrocarbon characteristic absorption regions, respectively.

4. The rapid quantitative detection and analysis method for total petroleum hydrocarbons in soil using infrared spectroscopy according to claim 1, characterized in that: The formula used to calculate the soil matrix scattering correction factor is as follows: in, Soil matrix scattering correction factor; This represents the background absorbance value of the non-feature absorption region after preprocessing. The baseline background absorbance value is the preset non-feature absorption range; The preset scattering sensitivity coefficient, and >

0.

5. The rapid quantitative detection and analysis method for total petroleum hydrocarbons in soil using infrared spectroscopy according to claim 4, characterized in that: The formula used to calculate the hydrocarbon structure correction factor is as follows: in, For hydrocarbon structure correction coefficients; This represents the ratio of the absorbance value of the characteristic absorption range of pretreated saturated hydrocarbons to the absorbance value of the characteristic absorption range of pretreated aromatic hydrocarbons. The calculation formula is: ,in, The absorbance values ​​are the characteristic absorption range of the pretreated saturated hydrocarbons. This represents the absorbance value of the characteristic absorption range of aromatic hydrocarbons after pretreatment. The baseline peak ratio of the preset standard TPH components; and These are the preset positive compensation strength coefficient and negative compensation strength coefficient, respectively; This is the preset lower limit value of the hydrocarbon structure correction coefficient.

6. The rapid quantitative detection and analysis method for total petroleum hydrocarbons in soil using infrared spectroscopy according to claim 5, characterized in that: The preset lower limit of the hydrocarbon structure correction coefficient is determined through the following calibration steps: N sets of reference soil samples were obtained. Under infrared spectroscopy detection conditions, M repeated measurements were performed on each set of reference soil samples. For each measurement, a parameter was set. The initial value is 1, and the hydrocarbon structure correction coefficients corresponding to each measurement are calculated to obtain... Each hydrocarbon structure correction factor is taken as follows: The lower quartiles of the hydrocarbon structure correction coefficients are used as the lower limits of the hydrocarbon structure correction coefficients, where N and M are preset positive integers, and N≥3 and M≥3.

7. The rapid quantitative detection and analysis method for total petroleum hydrocarbons in soil using infrared spectroscopy according to claim 6, characterized in that: The formula used to calculate the dynamic deviation threshold is as follows: in, The threshold for determining dynamic deviation; This is the preset benchmark deviation threshold.

8. The rapid quantitative detection and analysis method for total petroleum hydrocarbons in soil by infrared spectroscopy according to claim 7, characterized in that: The formula used to calculate the overall relative deviation of absorbance is as follows: in, This represents the overall relative deviation value of absorbance. The baseline absorbance value for the pre-defined characteristic absorption range of saturated hydrocarbons; The baseline absorbance value for the pre-defined characteristic absorption range of aromatic hydrocarbons; , These are the preset alkane weighting coefficients and preset aromatic weighting coefficients, respectively, and they satisfy... , >0, >

0.

9. The rapid quantitative detection and analysis method for total petroleum hydrocarbons in soil using infrared spectroscopy according to claim 8, characterized in that: The determination logic for whether the acquired infrared spectral data is valid is as follows: when ≤ When the infrared spectral data is obtained, it is determined to be valid; when > If this occurs, the acquired infrared spectral data is deemed invalid.

10. The rapid quantitative detection and analysis method for total petroleum hydrocarbons in soil by infrared spectroscopy according to claim 9, characterized in that: The execution logic for the corresponding processing instruction is as follows: When the acquired infrared spectral data is determined to be valid, the absorbance values ​​of the preprocessed saturated hydrocarbon characteristic absorption range and the aromatic hydrocarbon characteristic absorption range are input into the preset quantitative correction model to calculate the total petroleum hydrocarbon content in the target soil and output as the final detection result. When the acquired infrared spectral data is determined to be invalid, the currently acquired infrared spectral data is discarded, and a prompt to reacquire the data is triggered.

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