CN110836923A - Soil heavy metal concentration estimation method - Google Patents

Abstract

The embodiment of the present invention discloses a method for estimating the concentration of heavy metals in soil, and specifically relates to the technical field of heavy metal detection in soil. The specific steps are as follows: S1. Collect pH value, cation exchange capacity, organic carbon content and altitude data of the sampling point of soil sampling points; S2 . Use multiple regression analysis method to establish a mathematical model, and establish a linear relationship between the concentration of heavy metals and soil physical and chemical properties; S3. Input the required parameters into the formula to obtain the estimated concentration of heavy metals at this point; S4. Test the prediction result and the measured value of soil heavy metals. Consistency. The method integrates the physical and chemical properties of sampling points such as soil pH, cation exchange capacity, organic matter content and the altitude of the area as parameters to establish the correlation between heavy metal content and environmental factors, and realizes the prediction of heavy metal concentration around the study area, which is more scientific and effective. , to provide a reference for the degree of regional environmental pollution, and to provide a scientific basis for future environmental governance.

Description

A method for estimating the concentration of heavy metals in soil

technical field

The embodiments of the present invention relate to the technical field of soil heavy metal detection, in particular to a method for estimating the concentration of heavy metals in soil.

Background technique

Soil heavy metal pollution refers to that the content of trace metal elements in soil exceeds the background value due to human activities, and the content is too high due to excessive deposition. Heavy metal refers to metals with a specific gravity equal to or greater than 5.0, such as Fe, Mn, Zn , Cd, Hg, Ni, Co, etc. As is a metalloid, but because its chemical properties and environmental behavior are similar to heavy metals, arsenic is often included when discussing heavy metals, and some are directly included in In the range of heavy metals, due to the high content of iron and manganese in soil, they are generally considered not to be soil pollution elements. However, under strong reducing conditions, the toxicity caused by iron and manganese has also attracted enough attention. Estimate the concentration of heavy metals in soil. Contribute to the control of soil pollution.

The existing technology has the following shortcomings: most of the existing soil heavy metal concentration estimation methods use vegetation index, sampling point longitude and original data of sampling points as parameters to evaluate the overall pollution status of the region on a large spatial scale. The invention patent of CN 108563974 A, this method can only predict the approximate range of heavy metal content, and the prediction accuracy needs to be improved; For example, the altitude has a significant impact on the direction of precipitation runoff, and a large part of heavy metals will migrate with the rain, so the prediction accuracy of this method is not high.

Linear regression equation is a statistical analysis method that uses regression analysis in geographic statistics to determine the interdependent quantitative relationship between two or more variables. In the environmental field, it can be used to describe the potential relationship of multiple environmental factors. To estimate the impact of environmental factors on pollution, the present invention uses a regression equation to link the physical and chemical properties of the soil with the concentration of heavy metals for estimating the pollution degree of a region.

SUMMARY OF THE INVENTION

To this end, an embodiment of the present invention provides a method for estimating the concentration of heavy metals in soil. By integrating the physical and chemical properties of sampling points such as soil pH, cation exchange capacity, organic matter content, and the altitude of the region as parameters, the correlation between heavy metal content and environmental factors is established. Compared with the existing technology, it saves a lot of financial and material resources in the research process, which is more scientific and effective, provides a reference for the degree of regional environmental pollution, and provides a scientific basis for future environmental governance to solve the current situation. There is a problem of low prediction accuracy in technology.

In order to achieve the above purpose, the embodiment of the present invention provides the following technical solutions: a method for estimating the concentration of heavy metals in soil, the specific steps are as follows:

S1. Collect the pH value, cation exchange capacity, organic carbon content and altitude data of the sampling point of the soil sampling point;

S2. Use the multiple regression analysis method to establish a mathematical model, establish a linear relationship between the concentration of heavy metals and the physical and chemical properties of the soil, and realize the prediction of the concentration of heavy metals;

S3. Input the required parameters into the formula to obtain the estimated concentration of heavy metals at this point;

S4. Check the consistency between the predicted results and the measured values of soil heavy metals.

Further, in step S1, the pH value, cation exchange capacity and organic carbon content of the soil sampling point are all measured through experiments, and the altitude of the sampling point is obtained through GoogleEarth query.

Further, in step S2, the multiple regression equation is:

y=b ₀ +b ₁ x ₁ +b ₂ x ₂ +b ₃ x ₃ +b ₄ x ₄

为土壤采样点第k个环境参数的均值，

为所有土壤重金属采样点中Ni浓度的均值。Among them, k is the value of the kth environmental parameter related to the concentration of heavy metals, n is the number of soil heavy metal sampling points, _xik is the value of the kth environmental parameter of the soil at the ith sampling point, and y _i is the ith soil Ni concentration at each soil heavy metal sampling point,

is the mean value of the kth environmental parameter at the soil sampling point,

is the mean value of Ni concentration in all soil heavy metal sampling points.

Further, the linear relationship equation between heavy metal concentration and soil physical and chemical properties is obtained from the multiple regression equation:

y=79.916-9.701x ₁ +1.075x ₂ -1.606x ₃ +0.193x ₄

Among them, x ₁ is the soil pH value, x ₂ is the total organic carbon content of the soil, x ₃ is the altitude of the sampling point, and x ₄ is the cation exchange capacity of the soil at the sampling point.

Further, in step S4, the detailed steps of detecting the measured value of soil heavy metals are:

1) According to GPS positioning to reach a specific area, use the five-point sampling method to collect about 500g of soil samples of 0-20cm, wrap them in kraft paper, and label them;

2) The soil sample was air-dried naturally, ground with a ceramic mortar, and then passed through a 100-mesh sieve;

3) Take 0.1 g of soil sample, put it into a Teflon tube with 5 mL of aqua regia and 1 mL of hydrofluoric acid, both of which are of analytical grade, and digest it with a microwave digester, then evaporate it to 1 mL with an acid rushing device, and then use an ultra- Dilute to 40mL with pure water, to be tested;

4) On the machine, use an inductively coupled plasma mass spectrometer to analyze the content of heavy metals.

The embodiments of the present invention have the following advantages:

The invention integrates the physical and chemical properties of sampling points such as soil pH, cation exchange capacity, organic matter content and the altitude of the area as parameters, establishes the correlation between heavy metal content and environmental factors, and realizes the prediction of the concentration of heavy metals around the study area. In comparison, it saves a lot of financial and material resources in the research process, which is more scientific and effective, provides a reference for the degree of regional environmental pollution, and provides a scientific basis for future environmental governance.

Description of drawings

In order to illustrate the embodiments of the present invention or the technical solutions in the prior art more clearly, the following briefly introduces the accompanying drawings that are required to be used in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only exemplary, and for those of ordinary skill in the art, other implementation drawings can also be obtained according to the extension of the drawings provided without creative efforts.

The structures, proportions, sizes, etc. shown in this specification are only used to cooperate with the contents disclosed in the specification, so as to be understood and read by those who are familiar with the technology, and are not used to limit the conditions for the implementation of the present invention, so there is no technical The substantive meaning above, any modification of the structure, the change of the proportional relationship or the adjustment of the size should still fall within the technical content disclosed in the present invention without affecting the effect and the purpose that the present invention can produce. within the range that can be covered.

1 is a fitting result diagram of the measured value and predicted value of the heavy metal Ni provided in Example 3 of the present invention.

Detailed ways

The embodiments of the present invention are described below by specific specific embodiments. Those who are familiar with the technology can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. Obviously, the described embodiments are part of the present invention. , not all examples. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

Example 1:

The invention provides a method for estimating the concentration of heavy metals in soil, and the specific steps are as follows:

S1. Collect the pH value, cation exchange capacity, organic carbon content and altitude data of the soil sampling point. The pH value, cation exchange capacity and organic carbon content of the soil sampling point are all measured through experiments, and the altitude of the sampling point can be queried through GoogleEarth get;

S2. Use the multiple regression analysis method to establish a mathematical model, establish a linear relationship between the concentration of heavy metals and the physical and chemical properties of the soil, and realize the prediction of the concentration of heavy metals.

The multiple regression equation is:

y=b ₀ +b ₁ x ₁ +b ₂ x ₂ +b ₃ x ₃ +b ₄ x ₄

为土壤采样点第k个环境参数的均值，

为所有土壤重金属采样点中Ni浓度的均值，由多元回归方程式得出重金属浓度与土壤理化性质的线性关系方程为：Among them, k is the value of the kth environmental parameter related to the concentration of heavy metals, n is the number of soil heavy metal sampling points, _xik is the value of the kth environmental parameter of the soil at the ith sampling point, and y _i is the ith soil Ni concentration at each soil heavy metal sampling point,

is the mean value of the kth environmental parameter at the soil sampling point,

is the mean value of Ni concentration in all soil heavy metal sampling points, and the linear relationship equation between heavy metal concentration and soil physicochemical properties obtained from the multiple regression equation is:

y=79.916-9.701x ₁ +1.075x ₂ -1.606x ₃ +0.193x ₄

Among them, x ₁ is the soil pH value, x ₂ is the total organic carbon content of the soil, x ₃ is the altitude of the sampling point, and x ₄ is the cation exchange capacity of the soil at the sampling point.

S3. Input the required parameters into the formula to obtain the estimated concentration of heavy metals at this point;

S4. Check the consistency between the predicted results and the measured values of soil heavy metals.

Example 2:

The multiple regression equation is:

y=b ₀ +b ₁ x ₁ +b ₂ x ₂ +b ₃ x ₃ +b ₄ x ₄ ,

为土壤采样点第k个环境参数的均值，

为所有土壤重金属采样点中Ni浓度的均值，Linear regression equation is one of the statistical analysis methods that use regression analysis in mathematical statistics to determine the interdependent quantitative relationship between two or more variables. It is widely used. It is assumed that there is a linear correlation between random variables and variables. relationship, then the points (x, y) obtained from the experimental data will be scattered around a certain straight line, so it can be considered that the type of the regression function is a linear function. Specifically, in this embodiment, k is the kth correlation with the concentration of heavy metals The value of the environmental parameter, n is the number of soil heavy metal sampling points, x _ik is the value of the kth environmental parameter of the soil at the ith sampling point, _yi is the Ni concentration of the ith soil heavy metal sampling point,

is the mean value of the kth environmental parameter at the soil sampling point,

is the mean value of Ni concentration in all soil heavy metal sampling points,

The resulting equation is:

y=79.916-9.701x ₁ +1.075x ₂ -1.606x ₃ +0.193x ₄

Among them, x ₁ is the soil pH value, x ₂ is the total organic carbon content of the soil, x ₃ is the altitude of the sampling point, and x ₄ is the cation exchange capacity of the soil at the sampling point.

Example 3:

The measured values of soil heavy metals used in the present invention were sampled in Guiyu Town, Chaoyang District, Shantou City, Guangdong Province in August 2017, and were measured by microwave digestion and then inductively coupled plasma mass spectrometry (ICP-MS). 60 points, the detailed steps are:

1) According to GPS positioning to reach a specific area, use the five-point sampling method to collect about 500g of soil samples of 20cm, wrap them in kraft paper, and label them;

2) The soil sample was air-dried naturally, ground with a ceramic mortar, and then passed through a 100-mesh sieve;

3) Take 0.1 g of soil sample, put it into a Teflon tube with 5 mL of aqua regia and 1 mL of hydrofluoric acid, both of which are of analytical grade, and digest it with a microwave digester, then evaporate it to 1 mL with an acid rushing device, and then use an ultra- Dilute to 40mL with pure water, to be tested;

4) On the machine, use an inductively coupled plasma mass spectrometer to analyze the content of heavy metals.

测定，式中：c为盐酸标准溶液浓度(mol·L^-1)，V为滴定样品待测液所耗盐酸标准溶液量(mL)，V₀为空白滴定耗盐酸标准溶液量(mL)，m为风干试样质量(g)，10为将mmol换算成cmol的倍数，1000为换算成每kg中的cmol；采样点海拔高度通过GoogleEarth查询得到。The pH value, organic carbon content and cation exchange capacity of the soil at the above 60 sampling points were all measured by experiments, and the soil pH value could be determined by an acid meter; formula:

Determination, in the formula: c is the concentration of hydrochloric acid standard solution (mol·L ^-1 ), V is the amount of hydrochloric acid standard solution consumed by the liquid to be tested in the titration sample (mL), V ₀ is the amount of hydrochloric acid standard solution consumed by blank titration (mL), m is the mass of the air-dried sample (g), 10 is the multiple of converting mmol to cmol, and 1000 is the conversion to cmol per kg; the altitude of the sampling point is obtained through GoogleEarth query.

The values of 30 heavy metal concentrations, pH, organic carbon content and cation exchange capacity among the above measured values were subjected to regression analysis with excel, and the fitted curve was obtained:

y=79.916-9.701x ₁ +1.075x ₂ -1.606x ₃ +0.193x ₄

Substitute the values of pH, organic carbon content and cation exchange capacity of the remaining 30 points into the above formula to obtain the predicted heavy metal concentration y1, compare y1 with the measured concentration y of heavy metals at these 30 points, and remove outliers After processing, the fitting results are obtained, as shown in Table 1, the correlation coefficient R ² >70%, and the predicted results are highly consistent with the measured results.

average value minimum maximum value standard deviation Predictive value 15.09 7.88 24.91 4.37 Measured value 14.44 7.55 25.30 4.82

Table 1 The result table of the measured value and predicted value of heavy metal Ni (unit: mg/kg)

Example 4:

In the prior art, when the parameters of the equation are soil Cd concentration, organic matter and cation exchange capacity to predict the Cd content in rice, the correlation coefficient is 50.9%, which is lower than the equation provided by the present invention.

Although the present invention has been described in detail above with general description and specific embodiments, some modifications or improvements can be made on the basis of the present invention, which will be obvious to those skilled in the art. Therefore, these modifications or improvements made without departing from the spirit of the present invention fall within the scope of the claimed protection of the present invention.

Claims (5)

1. A soil heavy metal concentration estimation method is characterized by comprising the following steps: the method comprises the following specific steps:

s1, collecting the pH value, the cation exchange capacity, the organic carbon content and the altitude data of a soil sampling point;

s2, establishing a mathematical model by adopting a multiple regression analysis method, establishing a linear relation between the heavy metal concentration and the soil physicochemical property, and realizing the prediction of the heavy metal concentration;

s3, inputting the required parameters into a formula to obtain the estimated concentration of the heavy metal at the point;

and S4, testing the coincidence between the prediction result and the soil heavy metal measured value.

2. The soil heavy metal concentration estimation method according to claim 1, wherein: in step S1, the pH value, the cation exchange capacity, and the organic carbon content of the soil sampling point are all measured by experiments, and the altitude of the sampling point is obtained by google earth query.

3. The soil heavy metal concentration estimation method according to claim 1, wherein: in step S2, the multiple regression equation is:

y＝b₀+b₁x₁+b₂x₂+b₃x₃+b₄x₄

wherein k is the value of the kth environmental parameter related to the concentration of the heavy metal, n is the number of soil heavy metal sampling points, and x_ikIs the value of the kth environmental parameter, y, of the soil at the ith sampling point_iThe concentration of Ni at the ith soil heavy metal sampling point,

is the mean value of the kth environmental parameter of the soil sampling point,

and the concentration of Ni in all soil heavy metal sampling points is the average value.

4. The soil heavy metal concentration estimation method according to claim 2, wherein: the linear relation equation of the heavy metal concentration and the soil physicochemical property obtained by the multiple regression equation is as follows:

y＝79.916-9.701x₁+1.075x₂-1.606x₃+0.193x₄

wherein x is₁Is the pH value of the soil, x₂Is the total organic carbon content of soil, x₃Is the altitude, x, of the sample point₄The cation exchange capacity of the soil at the sampling point.

5. The soil heavy metal concentration estimation method according to claim 1, wherein: the detailed steps of the detection of the soil heavy metal measured value in step S4 are as follows:

1) according to the GPS positioning, when the soil reaches a specific area, collecting about 500g of a 0-20cm soil sample by a five-point sampling method, wrapping the soil sample by kraft paper, and attaching a label;

2) naturally drying the soil sample, grinding the soil sample by using a ceramic mortar, and then sieving the ground soil sample by using a 100-mesh sieve;

3) taking a 0.1g soil sample, putting 5mL of aqua regia and 1mL of hydrofluoric acid which are analytically pure into a Teflon tube, digesting by using a microwave digestion instrument, evaporating to dryness to 1mL by using an acid dispelling instrument, and fixing the volume to 40mL by using ultrapure water to be detected;

4) and (4) loading the sample on a machine, and analyzing the content of the heavy metal by using an inductively coupled plasma mass spectrometer.

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