A method for rapid assessment of vapor intrusion risk based on interfacial processes

Abstract

The application discloses a kind of vapor invasion risk rapid assessment method based on interface process, comprising the following steps: S1, find out site pollution condition and hydrogeological condition;S2, construct site indoor vapor invasion risk conceptual model;S3, calculate the attenuation coefficient that volatile transport in the soil or groundwater of pollution area is polluted to building indoor;S4, calculate the carcinogenic health risk and non-carcinogenic health risk of indoor vapor invasion exposure of different volatile organic pollutants;S5, 1x10 ‑6 As acceptable carcinogenic risk level evaluation target pollutant carcinogenic health risk, with 1 as acceptable hazard entropy evaluation target pollutant non-carcinogenic health risk;S6, determine the health risk of target pollutant by evaluation exceeding acceptable level, calculate the repair target value of target pollutant under the condition of acceptable carcinogenic risk level and the repair target value of target pollutant under the condition of acceptable non-carcinogenic risk level, take the low value in both as the final repair target value of target pollutant.

Description

Technical Field

[0001] This invention relates to the field of site contamination risk assessment technology, and specifically to a rapid assessment method for vapor intrusion risk based on interface processes. Background Technology

[0002] Volatile organic compounds (VOCs) are among the most commonly detected highly toxic pollutants in soil and groundwater at sites. Due to their volatility and strong mobility, the potential environmental risks they pose are significantly higher than those of other pollutants. Data released in 2000 by the U.S. Air Force Center of Environmental Excellence showed that groundwater plumes from tetrachloroethylene (a typical VOC) could reach nearly 4 kilometers in length. In China, the detection rate of VOCs in sites exceeds 70%, with individual sites involving contaminated soil and groundwater volumes exceeding 100,000 cubic meters, and some discovered groundwater plumes exceeding 1 kilometer in length. Even in scenarios where contaminated groundwater is not consumed or there is direct contact with contaminated soil, VOCs, due to their high volatility, can propagate upwards from groundwater or deep soil layers, penetrating clean vadose zones and building concrete foundations, eventually invading the interior of buildings. Inhalation of these vapors by people living and working indoors can harm their health; this process is also known as vapor intrusion. Therefore, both domestically and internationally, such sites are generally considered to pose a high risk of contamination and are a major factor restricting the safe reuse of these sites.

[0003] The United States was one of the first countries in the world to conduct research on VOCs vapor intrusion investigation technologies and risk assessment methods, and has established a relatively complete technical standard system. Based on the mining and analysis of over 20,000 pairs of monitoring data for different types of buildings, the U.S. Environmental Protection Agency recommends 0.03 as the attenuation coefficient for the risk screening and assessment stage. This helps technicians quickly screen buildings with potential indoor vapor intrusion risks based on groundwater or soil gas monitoring data, combined with site conceptual models, facilitating the further concentration of limited resources for detailed investigations or the implementation of corresponding risk management or remediation measures.

[0004] In my country, contaminated sites must undergo investigation, assessment, and remediation before proceeding with further redevelopment. Therefore, the focus of risk assessment is to evaluate the health risks to the population under future redevelopment scenarios based on soil and groundwater pollution investigation and monitoring results, using appropriate models. Current technical specifications use relatively complex models to assess the health risks of indoor vapor intrusion, involving more than 30 parameters and requiring specialized risk assessment software. Furthermore, the models themselves cannot characterize the physical transport process of VOCs at different media interfaces in the actual site, resulting in high uncertainty in the assessment results. Summary of the Invention

[0005] The purpose of this invention is to provide a rapid assessment method for vapor intrusion risk based on interface processes, in order to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, this invention provides a rapid vapor intrusion risk assessment method based on interface processes, comprising the following steps:

[0007] S1. Investigate the site's pollution status and hydrogeological conditions;

[0008] S2. Based on the standards, volatile organic pollutants are screened as pollutants of concern, a conceptual model of indoor vapor intrusion risk is constructed, and the exposure characteristics of future receptors, building structure and indoor ventilation design parameters of the site are determined.

[0009] S3. Calculate the attenuation coefficient of pollutants volatilized from soil or groundwater in the polluted area and transported to the interior of the building;

[0010] S4. Calculate the carcinogenic and non-carcinogenic health risks of indoor vapor intrusion exposure to different volatile organic pollutants;

[0011] S5, with 1×10 -6 As an acceptable carcinogenic risk level assessment, the carcinogenic health risk of the target pollutant is assessed, and 1 is used as the acceptable hazard entropy to assess the non-carcinogenic health risk of the target pollutant. If any type of risk calculated in step S4 exceeds the acceptable level, the health risk of the target pollutant is determined to exceed the acceptable level, and control or remediation is required.

[0012] S6. Based on the assessment in step S5, identify the target pollutant whose health risk exceeds the acceptable level, calculate the remediation target value of the target pollutant under the acceptable carcinogenic risk level, and calculate the remediation target value of the target pollutant under the acceptable non-carcinogenic risk level. Take the lower of the two values ​​as the final remediation target value of the target pollutant.

[0013] In a preferred embodiment, step S1 involves ascertaining the site pollution status and hydrogeological conditions, including: clarifying the soil and groundwater pollution status, stratigraphic distribution, and hydrogeological conditions through drilling sampling and testing, geophysical exploration, and on-site observation, including pollutant types, pollution levels, spatial distribution, soil layer distribution in the polluted area, thickness of soil layers of different properties, soil moisture content of soil layers of different properties, soil dry density of soil layers of different properties, soil organic carbon content of soil layers of different properties, groundwater depth, and interannual variation of groundwater level.

[0014] In a preferred embodiment, in step S3, the attenuation coefficient of pollutants volatilized from the soil or groundwater in the contaminated area and transported to the interior of the building is calculated using formula (1):

[0015]

[0016] Among them, AF T AF is the total attenuation coefficient of pollutants transported from the pollution source to the interior of the building, which is dimensionless;cap AF is the attenuation coefficient of pollutants transported from groundwater to the vadose zone soil layer, dimensionless; vs The attenuation coefficient of pollutants transported from the vadose zone soil layer to the foundation of the building is dimensionless; AF slab The attenuation coefficient of pollutants transported from under the building floor to the interior of the building is dimensionless.

[0017] In a preferred embodiment, in step S4, the carcinogenic health risk of indoor vapor intrusion exposure to different volatile organic pollutants is calculated using formula (2), and the non-carcinogenic health risk of indoor vapor intrusion exposure to different volatile organic pollutants is calculated using formula (3):

[0018] Risk c =C sg ×AF T ×EF i ×SF i ……(2);

[0019] Risk nc =C sg ×AF T ×EF i ÷(0.33×RfC i )……(3);

[0020] Among them, Risk c The carcinogenic risk of pollutants is dimensionless; Risk nc The pollutant poses a non-carcinogenic risk, dimensionless; C sg The concentration of pollutants in the soil atmosphere of the contaminated area is expressed in mg / m³. 3 ;EF i Exposure factors of receptors under different land use scenarios, in m 3 / (kg 体重 ·d); SF i The carcinogenic slope factor of pollutants via the respiratory pathway is expressed in units of 1 / (mg·kg). 体重 ·d); RfC i This is a reference concentration of pollutants via the respiratory pathway, in mg / m³. 3 .

[0021] In a preferred embodiment, in step S6, the remediation target value RG of the target contaminant under acceptable carcinogenic risk level is calculated using formula (4). c The remediation target value RG for the target pollutant under acceptable non-carcinogenic risk level conditions is calculated using formula (5). nc Take RG c and RG nc The lower value in the range is taken as the final remediation target value for the target pollutant:

[0022] RG c =1×10 -6 ÷(AF T ×EF i ×SF i )……(4);

[0023] RG nc = (0.33×RfC) i )÷(AF T ×EF i )……(5).

[0024] In a preferred embodiment, in step S3, the attenuation coefficient of pollutants volatilized from the soil or groundwater in the contaminated area and transported to the interior of the building is calculated using formula (1). If the pollutants are only present in the vadose zone soil, formula (1) is further simplified to formula (6). If the specific location of the future building is unknown when assessing the risk, formula (1) is further simplified to formula (7).

[0025]

[0026] In a preferred embodiment, in step S3, the attenuation coefficient of pollutants transported from groundwater to the vadose zone soil layer is calculated using formula (8), the attenuation coefficient of pollutants transported from the vadose zone soil layer to the floor of the building is calculated using formula (9), and the attenuation coefficient of pollutants transported from the floor of the building to the interior of the building is calculated using formula (10).

[0027]

[0028] Among them, L b L represents the future building height in cm; Lc represents the thickness of the capillary soil layer in cm; L vs L represents the thickness of the vadose zone soil layer, in cm. slab The thickness of the building's foundation slab is in cm; ER is the building's indoor air exchange rate, in 1 / s; D a The diffusion coefficient of pollutants in air, expressed in cm. 2 / s;D w The diffusion coefficient of pollutants in water, expressed in cm. 2 / s; H is the Henry's coefficient for the target pollutant, dimensionless; θ ca θ represents the proportion of air volume to total pore volume in capillary soil, dimensionless; cw θ represents the proportion of water volume to total pore volume in the capillary zone of the soil, dimensionless; ct θ represents the total pore volume in the capillary zone of the soil, dimensionless; va θ represents the proportion of air volume to total pore volume in the vadose zone soil, a dimensionless quantity. vtMW represents the total pore volume in the vadose zone soil, dimensionless; MW represents the molecular weight of the pollutant, in g / mol.

[0029] In a preferred embodiment, in step S4, when the plot is planned to be designated as a sensitive land use, EF i The value is 0.075m. 3 / (kg body weight·d), when the land is designated as a non-sensitive use, EF i The value is 0.121m. 3 / (kg body weight·d); C sg The concentration of pollutants of concern can be obtained by directly monitoring the concentration of pollutants in the soil atmosphere of the contaminated area, or by calculating the concentration of pollutants of concern detected in the soil or groundwater using theoretical formulas in the technical specifications.

[0030] In a preferred embodiment, in step S3, when the attenuation coefficient of pollutants transported from the vadose zone soil layer to the building floor is calculated using formula (9), if there are soil layers of different properties in the vadose zone between the polluted area and the building floor, formula (11) is further used to calculate AF. vs :

[0031]

[0032] Among them, L vsi θ represents the thickness of the i-th soil type in the vadose zone, in cm; vai θ represents the air porosity of the i-th soil type in the vadose zone, which is dimensionless; vti The total porosity of the i-th soil type in the vadose zone is dimensionless.

[0033] Compared with the prior art, the beneficial effects of the present invention are:

[0034] This invention proposes a rapid assessment method for evaluating the health risks of indoor vapor intrusion of pollutants by combining a conceptual model of indoor VOCs pollution risk in typical sites and based on the physical process of pollutant transport from the pollution source area to the indoor air of buildings across media interfaces. Compared with existing technical standards such as HJ25.3, which require more than 30 model parameters, the assessment method in this invention only requires three data points: the concentration of the pollutant of interest, the soil layer thickness of different soil types in the vadose zone, and the building foundation thickness. By referring to technical manuals, it is possible to quickly assess the health risks of indoor vapor intrusion even in scenarios without specialized software, improving the work efficiency of technical personnel and the timeliness of assessment results, and providing important technical support for environmental management decisions.

[0035] Furthermore, due to differences in building structures, domestic regulations require that the width of cracks in the concrete foundation slab of underground structures should not exceed 0.2 mm. However, existing domestic assessment models such as HJ25.3, when quantifying the process of pollutants penetrating the building foundation slab and entering the indoor air, assume the existence of cracks approximately 1 mm wide in the building foundation slab, through which pollutants are transported and enter the indoor air under the influence of concentration gradients. Therefore, the model assumptions in domestic guidelines such as HJ25.3 deviate from reality and cannot accurately depict the process of VOCs entering the indoor air in actual sites, resulting in high uncertainty in the assessment results. Given the structural characteristics of building concrete foundation slabs, which are primarily composed of capillary pores, this invention, based on the capillary porous media transport theory, employs a full-section diffusion model to characterize the physical process of target pollutants entering the indoor air from the building foundation slab and quantifies the attenuation coefficient. This makes the assessment results closer to the actual scenario, improving the accuracy of the assessment results by approximately 10 times, providing scientific support for environmental management decisions, and avoiding the potential for underestimation of risk in existing models. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of the method flow of the present invention;

[0037] Figure 2 This is a site concept model for Implementation Example 2 of the present invention;

[0038] Figure 3 This is a site concept model for Implementation Example 3 of the present invention. Detailed Implementation

[0039] The technical solutions in the embodiments of the present invention will be clearly and completely described below. All other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of the present invention.

[0040] Example 1

[0041] like Figures 1 to 3 As shown, the preferred embodiment of the present invention, a rapid vapor intrusion risk assessment method based on interface processes, includes the following steps:

[0042] Step S1: Investigate the site pollution status and hydrogeological conditions, including: through drilling and sampling, geophysical exploration and on-site observation, investigate the soil and groundwater pollution status, stratigraphic distribution and hydrogeological conditions, including pollutant type, pollution degree, spatial distribution, soil layer distribution in the polluted area, thickness of soil layers of different properties, soil moisture content of soil layers of different properties, soil dry density of soil layers of different properties, soil organic carbon content of soil layers of different properties, groundwater depth and interannual variation of groundwater level.

[0043] Step S2: Based on the specifications, volatile organic pollutants are screened as pollutants of concern, a conceptual model of indoor vapor intrusion risk is constructed, and the exposure characteristics of future receptors, building structure and indoor ventilation design parameters of the site are determined.

[0044] Step S3: Calculate the attenuation coefficient of pollutant volatilization and transport to the building interior using formula (1):

[0045]

[0046] Among them, AF T AF is the total attenuation coefficient of pollutants transported from the pollution source to the interior of the building, which is dimensionless; cap AF is the attenuation coefficient of pollutants transported from groundwater to the vadose zone soil layer, dimensionless; vs The attenuation coefficient of pollutants transported from the vadose zone soil layer to the foundation of the building is dimensionless; AF slab The attenuation coefficient of pollutants transported from under the building floor to the interior of the building is dimensionless.

[0047] Furthermore, in step S3, the attenuation coefficient of pollutants volatilized from the soil or groundwater in the contaminated area and transported to the interior of the building is calculated using formula (1). If the pollutants are only present in the vadose zone soil, formula (1) is further simplified to formula (6). If the specific location of the future building is unknown when assessing the risk, formula (1) is further simplified to formula (7).

[0048]

[0049] In a preferred embodiment, in step S3, the attenuation coefficient of pollutants transported from groundwater to the vadose zone soil layer is calculated using formula (8), the attenuation coefficient of pollutants transported from the vadose zone soil layer to the floor of the building is calculated using formula (9), and the attenuation coefficient of pollutants transported from the floor of the building to the interior of the building is calculated using formula (10).

[0050]

[0051] Among them, L b L represents the future building height in cm; Lc represents the thickness of the capillary soil layer in cm; L vs L represents the thickness of the vadose zone soil layer, in cm. slab The thickness of the building's foundation slab is in cm; ER is the building's indoor air exchange rate, in 1 / s; D a The diffusion coefficient of pollutants in air, expressed in cm. 2 / s;D w The diffusion coefficient of pollutants in water, expressed in cm. 2 / s; H is the Henry's coefficient for the target pollutant, dimensionless; θ ca θ represents the proportion of air volume to total pore volume in capillary soil, dimensionless; cw θ represents the proportion of water volume to total pore volume in the capillary zone of the soil, dimensionless; ct θ represents the total pore volume in the capillary zone of the soil, dimensionless; va θ represents the proportion of air volume to total pore volume in the vadose zone soil, a dimensionless quantity. vt MW represents the total pore volume in the vadose zone soil, dimensionless; MW represents the molecular weight of the pollutant, in g / mol.

[0052] Furthermore, in step S3, when using formula (9) to calculate the attenuation coefficient of pollutants transported from the vadose zone soil layer to the building floor, if there are soil layers of different properties in the vadose zone between the polluted area and the building floor, formula (11) is further used to calculate AF. vs :

[0053]

[0054] Among them, L vsi θ represents the thickness of the i-th soil type in the vadose zone, in cm; vai θ represents the air porosity of the i-th soil type in the vadose zone, which is dimensionless; vti The total porosity of the i-th soil type in the vadose zone is dimensionless.

[0055] Furthermore, when using formulas (8), (9), and (10) to calculate the attenuation coefficients of pollutants transported through different interfaces, Table 1 can be used to quickly look up the corresponding calculation items.

[0056] Table 1 Quick Reference Table for AF Calculation

[0057]

[0058] Step S4: Calculate the carcinogenic health risk of indoor vapor intrusion exposure to different volatile organic pollutants using formula (2), and calculate the non-carcinogenic health risk of indoor vapor intrusion exposure to different volatile organic pollutants using formula (3):

[0059] Risk c =C sg ×AF T ×EF i ×SF i ……(2);

[0060] Risk nc =C sg ×AF T ×EF i÷(0.33×RfC i )……(3);

[0061] Among them, Risk c The carcinogenic risk of pollutants is dimensionless; Risk nc The pollutant poses a non-carcinogenic risk, dimensionless; C sg The concentration of pollutants in the soil atmosphere of the contaminated area is expressed in mg / m³. 3 ;EF i Exposure factors of receptors under different land use scenarios, in m 3 / (kg 体重 ·d); SF i The carcinogenic slope factor of pollutants via the respiratory pathway is expressed in units of 1 / (mg·kg). 体重 ·d), can be obtained by consulting relevant standards and specifications; RfC i This is a reference concentration of pollutants via the respiratory pathway, in mg / m³. 3 This can be obtained by consulting relevant standards and specifications.

[0062] Furthermore, in step S4, when the plot is planned for future residential or other sensitive uses, EF i The value is 0.075m. 3 / (kg body weight·d), when planned for non-sensitive uses such as industrial and commercial land, EF i The value is 0.121m. 3 / (kg body weight·d); C sg The concentration of pollutants of concern can be obtained by directly monitoring the concentration of pollutants in the soil atmosphere of the polluted area, or by using theoretical formulas in technical specifications such as HJ25.3 to calculate the concentration of pollutants of concern detected in the soil or groundwater.

[0063] Step S5, with 1×10 -6 As an acceptable carcinogenic risk level assessment, the carcinogenic health risk of the target pollutant is assessed, and 1 is used as the acceptable hazard entropy to assess the non-carcinogenic health risk of the target pollutant. If any type of risk calculated in step S4 exceeds the acceptable level, the health risk of the target pollutant is determined to exceed the acceptable level, and control or remediation is required.

[0064] Step S6: Based on the assessment in Step S5, identify the target pollutant whose health risk exceeds the acceptable level, calculate the remediation target value of the target pollutant under the acceptable carcinogenic risk level, and calculate the remediation target value of the target pollutant under the acceptable non-carcinogenic risk level. Take the lower of the two values ​​as the final remediation target value of the target pollutant.

[0065] Furthermore, in step S6, the remediation target value RG for the target pollutant under acceptable carcinogenic risk level conditions is calculated using formula (4). cThe remediation target value RG for the target pollutant under acceptable non-carcinogenic risk level conditions is calculated using formula (5). nc Take RG c and RG nc The lower value in the range is taken as the final remediation target value for the target pollutant:

[0066] RG c =1×10 -6 ÷(AF T ×EF i ×SF i )……(4);

[0067] RG nc = (0.33×RfC) i )÷(AF T ×EF i )……(5).

[0068] Example 2

[0069] This embodiment uses the risk assessment and remediation target value determination of carbon tetrachloride indoor vapor intrusion pollution in the soil of a certain site as an example to explain the method of the present invention in detail.

[0070] In this example: the total area of ​​the site is approximately 8000m². 2 Historically, parts of the site have been used as chemical plants. According to relevant management requirements, an investigation and risk assessment of soil and groundwater pollution must be conducted to ensure the site can be used safely.

[0071] Step S1: According to technical specifications, 20 soil sampling points were set up on the site. A soil sample was collected at 1-meter intervals along the vertical direction from each sampling point for analysis. Each sampling point was tested until no pollutants were detected, totaling 120 soil samples. Results showed that carbon tetrachloride was detected in the soil of the 2000-square-meter area where the historical production workshop was located, with the maximum detection depth reaching 8 meters below the ground surface. No groundwater pollution was found. Since carbon tetrachloride is a typical VOC, according to specifications, 20 soil gas monitoring wells were further set up on the site. Soil gas samples were collected layer by layer from each monitoring well, totaling 60 soil gas samples collected and monitored, averaging 3 samples per monitoring well. Borehole core data showed that the vadose zone soil layer in the contaminated area was relatively simple, mainly composed of silt.

[0072] Step S2: Based on the pollution and hydrogeological survey results from Step S1, construct a conceptual model of the site's indoor vapor intrusion risk, as shown in the attached figure. Figure 2 As shown. Because the site is planned for Class II residential use, the future site exposure characteristics are considered based on residential land use. The future building foundation thickness L... slabApproximately 50cm, but the specific depth of the building's foundation slab could not be obtained.

[0073] Step S3: Since the specific burial depth of the future building foundation is unknown, the total attenuation coefficient AF is calculated using formulas (7) and (10) in a conservative manner. T According to the specifications, carbon tetrachloride has a molecular weight of 153.84 g / mol, and the residential land use permit L... b ×ER is 3.1×10 -2 Therefore, the total attenuation coefficient AF is calculated. T 8×10 -6 .

[0074]

[0075] Step S4: Since soil gas monitoring was conducted in the contaminated area, the upper confidence limit of 3.54 mg / m³, representing the average value of the soil gas detection results in the contaminated area, is directly used. 3 The concentration of carbon tetrachloride in the soil atmosphere of the contaminated area. Because the site is planned for residential use, the receptor's exposure factor EF... i It is 0.75m 3 / (kg body weight·d). According to the technical specifications, the SF6 of carbon tetrachloride... i 2.56×10 -2 (mg·kg 体重 ·d) -1 RfC i 0.1 mg / m 3 Substituting into equation (2), the calculated indoor carcinogenic health risk of carbon tetrachloride vapor intrusion in the case site soil is 5.44 × 10⁻⁶. -7 Substituting into equation (3), the non-carcinogenic risk of indoor vapor intrusion of carbon tetrachloride in the soil of the case site is calculated to be 6.44 × 10⁻⁶. -3 .

[0076] Risk c =C sg ×AF T ×EF i ×SF i ……(2);

[0077] Risk nc =C sg ×AF T ×EF i ÷(0.33×RfC i )……(3).

[0078] Step S5, 1×10 -6Assessing the carcinogenic health risk of the target pollutant using an acceptable carcinogenic risk level, and assessing the non-carcinogenic health risk of the target pollutant using 1 as the acceptable hazard entropy. Compare this to the carcinogenic risk calculation result of 5.44 × 10⁻⁶ in step 4. -7 The non-carcinogenic risk calculation result is 6.44×10 -3 It can be seen that when the site is planned to be redeveloped for residential use, the health risk of indoor vapor intrusion from carbon tetrachloride pollution in the soil is acceptable, and no remediation or risk management is required.

[0079] Example 3

[0080] Taking the risk assessment and remediation target value determination of trichloroethylene indoor vapor intrusion pollution in groundwater of a certain site as an example, the method of the present invention is described in detail.

[0081] In this example: the total area of ​​the site is approximately 20,000 m². 2 There is a cleaning plant upstream of the groundwater outside the site. The soil and groundwater within the plant area have been found to be contaminated with trichloroethylene, and the trichloroethylene contamination in the groundwater has exceeded the land use boundary of the site, indicating a high possibility of migration to the case site. According to relevant management requirements, an investigation and risk assessment of the soil and groundwater contamination status within the case site must be conducted to ensure the safe use of the site.

[0082] Step S1: In accordance with technical specifications, 20 groundwater monitoring wells were installed on site. Results showed trichloroethylene contamination in the groundwater, with an average detection concentration of 1.5 mg / L. Borehole core data indicated that the stable groundwater level at the site was approximately 8.0 meters below the surface, with a groundwater capillary height of approximately 50 cm. The soil composition was predominantly silt. The average thickness of the vadose zone was 750 cm, consisting of silt (average thickness 100 cm), clay (average thickness 250 cm), sand (average thickness approximately 250 cm), and fill (average thickness approximately 150 cm) from bottom to top.

[0083] Step S2: Based on the pollution and hydrogeological survey results from Step S1, construct a conceptual model of the site's indoor vapor intrusion risk, as shown in the attached figure. Figure 3 As shown. Because the site is planned as a Class II residential land, its future receptor exposure characteristics will be considered according to residential land use standards. The future building foundation thickness L... slab It is about 50cm deep and buried about 3 meters below the ground.

[0084] Step S3: Referring to Table 1, we can see that the capillary band of silt... L c =50cm. Silt in the vadose zone. L vs =100cm. Clay L vs =250cm. Sandy soil L vs =100cm. The diffusion coefficient of trichloroethylene in air is 6.87×10. -2 The diffusion coefficient in water is 1.02 × 10⁻⁶. -5 The Henry's law constant is 0.403, and the molecular weight is 131.39 g / mol. Residential land L b ×ER is 3.1×10 -2 Therefore, combining formulas (1), (8), (11), and (10), the total attenuation coefficient AF of trichloroethylene in groundwater transmitted to the indoor air of buildings is calculated. T It is 7.55×10 -6 ;

[0085]

[0086] Step S4: During the pollution investigation, only groundwater was monitored. Using Henry's Law, the corresponding concentration of trichloroethylene in the soil atmosphere when the average concentration of trichloroethylene in the groundwater was 1.5 mg / L was calculated to be 604.5 mg / m³. 3 This is used as the concentration of trichloroethylene in the soil atmosphere of the contaminated area. The site is planned for residential use, and the receptor exposure factor is 0.75m. 3 / (kg body weight·d). According to the technical specifications, the SF6 of carbon tetrachloride... i 1.75×10 -2 (mg·kg 体重 ·d) -1 RfC i It is 0.002 mg / m³ 3 Substituting into formula (2), the carcinogenic health risk of trichloroethylene in the groundwater of the case site is calculated to be 5.99 × 10⁻⁶. -6 Substituting into equation (3), the non-carcinogenic risk of trichloroethylene in the groundwater of the case site is calculated to be 5.19.

[0087] Risk c =C sg ×AF T ×EF i ×SF i ……(2);

[0088] Risk nc =C sg ×AF T ×EF i ÷(0.33×RfC i )……(3).

[0089] Step S5, with 1×10 -6Assessing the carcinogenic health risk of the target pollutant using an acceptable carcinogenic risk level, and assessing the non-carcinogenic health risk of the target pollutant using 1 as the acceptable hazard entropy. Compare this to the carcinogenic risk calculation result of 5.99 × 10⁻⁶ in step S4. -6 According to the non-carcinogenic risk calculation result 5.19, if the site is planned to be redeveloped for residential use in the future, the health risk of indoor vapor intrusion from trichloroethylene pollution in the groundwater exceeds the acceptable level, and remediation or risk management is required.

[0090] Step S6: Calculate the remediation target value RG of trichloroethylene in the groundwater of the case site under acceptable carcinogenic risk level using formula (4). c The remediation target value RG of trichloroethylene in the groundwater of the case site under acceptable non-carcinogenic risk level was calculated using formula (5) at a concentration of 0.25 mg / L. nc The concentration was 0.29 mg / L. Therefore, the final remediation target value for trichloroethylene in the groundwater at the case site was 0.25 mg / L.

[0091] RG c =1×10 -6 ÷(AF T ×EF i ×SF i )……(4);

[0092] RG nc = (0.33×RfC) i )÷(AF T ×EF i )……(5).

[0093] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for rapid assessment of vapor intrusion risk based on interfacial processes, characterized in that: The method comprises the following steps: S1, finding out the pollution condition and hydrogeological condition of the site; S2, screening volatile organic pollutants as concerned pollutants according to the standard, constructing a site indoor vapor intrusion risk conceptual model, determining the exposure characteristics of future receptors of the site, building structure and indoor ventilation design parameters; S3, calculating the attenuation coefficient of the volatile transport of the pollutants in the soil or groundwater in the pollution area to the indoor of the building; S4, calculating the carcinogenic health risk and non-carcinogenic health risk of indoor vapor intrusion exposure of different volatile organic pollutants; S5、with 1 x 10 -6 Assess the carcinogenic health risk of the target pollutant as the acceptable carcinogenic risk level, and assess the non-carcinogenic health risk of the target pollutant as the acceptable hazard entropy with 1. If any of the risks calculated in step S4 exceeds the acceptable level, it is determined that the health risk of the target pollutant exceeds the acceptable level, and control or remediation is required. S6, determining the target pollutants whose health risks exceed the acceptable level through step S5, calculating the remediation target value of the target pollutants under the condition of acceptable carcinogenic risk level, and calculating the remediation target value of the target pollutants under the condition of acceptable non-carcinogenic risk level, and taking the lower value of the two as the final remediation target value of the target pollutants; In step S3, the attenuation coefficient of the volatile transport of the pollutants in the soil or groundwater in the pollution area to the indoor of the building is calculated by formula (1): where AF T is the total attenuation coefficient for the transport of the contaminant from the source to the indoor air of the building, dimensionless; AF cap is the attenuation coefficient for the transport of the contaminant from the groundwater to the unsaturated zone, dimensionless; AF vs is the attenuation coefficient for the transport of the contaminant from the unsaturated zone to the sub-floor of the building, dimensionless; and AF slab is the attenuation coefficient for the transport of the contaminant from the sub-floor of the building to the indoor air of the building, dimensionless.

2. The method of claim 1, wherein: In step S1, the pollution condition and hydrogeological condition of the site are found out, including: through drilling sampling detection, geophysical exploration and field observation means, the pollution condition of soil and groundwater, stratum distribution and hydrogeological condition are found out, including the type of pollutants, pollution degree, spatial distribution, soil layer distribution in the pollution area, thickness of soil layers with different properties, soil moisture content of soil layers with different properties, soil dry density of soil layers with different properties, soil organic carbon content of soil layers with different properties, groundwater depth and annual variation amplitude of groundwater level.

3. The method of claim 1, wherein: In step S4, the carcinogenic health risk of indoor vapor intrusion exposure of different volatile organic pollutants is calculated by formula (2), and the non-carcinogenic health risk of indoor vapor intrusion exposure of different volatile organic pollutants is calculated by formula (3): Risk c = C sg x AF T x EF i x SF i …(2); Risk nc = C sg × AF T × EF i ÷ (0.33 x RFC i ) … (3); wherein, Risk c is the carcinogenic risk of the pollutant, dimensionless; Risk nc is the non-carcinogenic risk of the pollutant, dimensionless; C sg is the concentration of the pollutant in the soil gas of the contaminated area, with the unit of mg / m 3 ; EF i is the exposure factor of the receptor under different land use scenarios, with the unit of m 3 / (kg 体重 ·d); SF i is the carcinogenic slope factor of the respiratory pathway of the pollutant, with the unit of 1 / (mg·kg 体重 ·d); RfC i is the reference concentration of the respiratory pathway of the pollutant, with the unit of mg / m 3 .

4. The method of claim 3, wherein: In step S6, the restoration target value RG of the target pollutant under the acceptable carcinogenic risk level is calculated using formula (4) c The restoration target value RG of the target pollutant under the acceptable non-carcinogenic risk level is calculated using formula (5) nc The lower value of RG c and RG nc is taken as the final restoration target value of the target pollutant. RG c = 1 x 10 -6 ÷ (AF T x EF i x SF i ) … (4); RG nc = (0.33 x RfC i ) ÷ (AF T x EF i ) … (5).

5. The method of claim 4, wherein: In step S3, formula (1) is used to calculate the attenuation coefficient of the volatile transport of the pollutants in the soil or groundwater in the pollution area to the indoor of the building, if the pollutants only exist in the soil of the aeration zone, formula (1) is further simplified as formula (6), and if the specific position of the future building is unknown when the risk is evaluated, formula (1) is further simplified as formula (7):

6. The method of claim 5, wherein: In step S3, formula (8) is used to calculate the attenuation coefficient of the transport of the pollutants from the groundwater to the soil layer of the aeration zone, formula (9) is used to calculate the attenuation coefficient of the transport of the pollutants from the soil layer of the aeration zone to the bottom plate of the building, and formula (10) is used to calculate the attenuation coefficient of the transport of the pollutants from the bottom plate of the building to the indoor of the building: wherein, L b is the future building story height, in cm; Lc is the capillary zone soil layer thickness, in cm; L vs is the vadose zone soil layer thickness, in cm; L slab is the building floor thickness, in cm; ER is the building indoor air exchange rate, in 1 / s; D a is the pollutant diffusion coefficient in air, in cm 2 / s; D w is the pollutant diffusion coefficient in water, in cm 2 / s; H is the target pollutant Henry’s law coefficient, dimensionless; θ ca is the capillary zone soil air volume fraction of total pore volume, dimensionless; θ cw is the capillary zone soil water volume fraction of total pore volume, dimensionless; θ ct is the capillary zone soil total pore volume, dimensionless; θ va is the vadose zone soil air volume fraction of total pore volume, dimensionless; θ vt is the vadose zone soil total pore volume, dimensionless; MW is the pollutant molecular weight, in g / mol.

7. The method of claim 3, wherein: EF = 0.075 m / (kg body weight.d) when the future planning of the plot is sensitive land i EF = 0.075 m / (kg body weight.d) when the future planning of the plot is sensitive land 3 EF = 0.121 m / (kg body weight.d) when the future planning of the plot is non-sensitive land i EF = 0.121 m / (kg body weight.d) when the future planning of the plot is non-sensitive land 3 EF = 0.121 m / (kg body weight.d) when the future planning of the plot is non-sensitive land sg The value is obtained by directly monitoring the concentration of the concerned pollutant in the soil gas of the contaminated area, or calculated from the detected concentration of the concerned pollutant in the soil or groundwater by using the theoretical formula in the technical specification.

8. The method of claim 6, wherein: In step S3, when the attenuation coefficient of the transport of the contaminant from the soil layer of the vadose zone to the bottom of the building is calculated using formula (9), if there are different soil layers in the vadose zone between the contaminated area and the bottom of the building, formula (11) is further used to calculate AF vs : wherein L vsi is the thickness of the i-th soil type of the unsaturated zone soil layer, in cm; θ vai is the soil air void fraction of the i-th soil type of the unsaturated zone soil layer, dimensionless; θ vti is the total soil void fraction of the i-th soil type of the unsaturated zone soil layer, dimensionless.

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