Soil heavy metal pollution evaluation method based on enrichment migration characteristics

Abstract

The invention discloses a soil heavy metal pollution evaluation method based on enrichment migration characteristics, and the method comprises the following steps: S1, collecting a soil sample, and determining the element content of the soil sample; s2, calculating a heavy metal element enrichment coefficient of the soil sample; s3, calculating a heavy metal element migration coefficient of the soil sample; s4, evaluating the heavy metal pollution of the soil sample. According to the method, the surface soil sample and the deep soil sample are collected at the same point, the enrichment coefficient and the migration coefficient of the surface soil sample are calculated by taking the deep soil sample as a background value, and soil heavy metal pollution evaluation is further performed according to the enrichment coefficient and the migration coefficient. The problem that it is difficult to obtain the real and accurate soil heavy metal pollution situation when a single reference background value is taken and the soil heavy metal pollution is evaluated directly according to the enrichment degree is solved.

Description

Technical Field

[0001] The present invention relates to the field of soil heavy metal pollution assessment, and in particular to a soil heavy metal pollution assessment method based on enrichment migration characteristics. Background Art

[0002] Heavy metal pollution in soil has become a difficult and hot issue that has attracted widespread attention from all over the world due to its concealment, durability and irreversibility. Existing soil heavy metal pollution assessment methods mainly include single factor pollution index method, Nemerow pollution index method, geoaccumulation index method, pollution load index method, etc. These methods are essentially based on the enrichment of heavy metals in the soil to evaluate pollution. However, in fact, these evaluation methods confuse the relationship between enrichment and pollution. Because the enrichment of heavy metals in soil is not necessarily caused by pollution, the leaching of other elements in the soil may also cause the relative enrichment of heavy metals. Directly evaluating soil heavy metal pollution based on the degree of enrichment may lead to inaccurate evaluation results. In addition, these evaluation methods all involve the selection of reference background values. Existing methods mostly use the soil heavy metal background value of a single region as the reference background value. However, the soil itself is heterogeneous, and the soil heavy metal background value in different locations is likely to be different. Therefore, it is difficult to reflect the true situation of soil heavy metal pollution by taking a single regional reference background value for evaluation. Summary of the invention

[0003] The purpose of the present invention is to provide a soil heavy metal pollution evaluation method based on enrichment migration characteristics, so as to solve the problem proposed in the above-mentioned background technology that it is difficult to obtain a true and accurate soil heavy metal pollution situation by taking a single reference background value and directly evaluating the soil heavy metal pollution according to the enrichment degree.

[0004] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0005] A soil heavy metal pollution assessment method based on enrichment migration characteristics comprises the following steps:

[0006] S1. Collect soil samples and determine the element content of soil samples:

[0007] Collect surface and deep soil samples at the same point in the target area, air-dry or bake the soil samples and send them to the laboratory to determine the content of heavy metal elements and inert elements;

[0008] S2. Calculate the enrichment coefficient of heavy metal elements in soil samples:

[0009] The enrichment coefficient calculation formula is as follows:

[0010] R i =C i / B i

[0011] In the formula, R i is the enrichment coefficient of heavy metal element i in the surface soil sample; C i is the content of heavy metal element i in the surface soil sample; B i is the content of heavy metal element i in deep soil samples; R i >1 indicates that the soil is enriched with heavy metal elements, R i =1 indicates that there is no enrichment or depletion of heavy metal elements in the soil, R i <1 indicates that the soil is depleted of heavy metal elements;

[0012] S3. Calculate the migration coefficient of heavy metal elements in soil samples:

[0013] The migration coefficient is calculated as follows:

[0014] M i =(C i / C j ) / (B i / B j )-1

[0015] Where M i is the migration coefficient of heavy metal element i in the surface soil sample; C i and C j are the contents of heavy metal element i and inert element j in surface soil samples; B i and B j are the contents of heavy metal element i and inert element j in deep soil samples; M i >0 indicates a net migration of heavy metal elements i into the soil, M i = 0 indicates that there is no net inflow or outflow of heavy metal element i in the soil, M i <0 indicates a net outflow of heavy metal elements i from the soil;

[0016] S4. Evaluate the heavy metal pollution of soil samples:

[0017] According to the enrichment factor R i >1 and the migration coefficient M i >0, the soil samples contaminated by heavy metals were screened out, and further enrichment coefficient R i Classify and grade the contamination levels of soil samples contaminated by heavy metals.

[0018] Preferably, in step S1, the sampling depth of the deep soil sample is below 100 cm, and the inert element is selected from aluminum (Al) or titanium (Ti).

[0019] Preferably, in step S4, the classification and grading method adopts the natural breakpoint method.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows: by collecting surface and deep soil samples at the same point, and using the deep soil samples as the background value to calculate the enrichment coefficient and migration coefficient of the surface soil samples, and further evaluating the soil heavy metal pollution based on the enrichment coefficient and migration coefficient, the soil heavy metal pollution situation can be reflected more truly and accurately. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0022] Figure 1 It is a schematic diagram of the steps of the present invention;

[0023] Figure 2 is a box plot of the enrichment coefficient of heavy metal element lead (Pb) in the soil samples of the embodiments of the present invention;

[0024] Figure 3 is a box plot of the migration coefficient of heavy metal element lead (Pb) in the soil sample of the embodiment of the present invention;

[0025] Figure 4 It is a schematic diagram of the proportion of each pollution level of the heavy metal element lead (Pb) in the soil sample of the embodiment of the present invention. DETAILED DESCRIPTION

[0026] The preferred embodiments of the present invention are described below in conjunction with the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0027] Example 1

[0028] like Figure 1 As shown, the present invention provides a soil heavy metal pollution assessment method based on enrichment migration characteristics, comprising the following steps:

[0029] S1. Collect soil samples and determine the element content of soil samples:

[0030] Collect surface and deep soil samples at the same point in the target area. The sampling depth of surface soil samples is 0-20cm, and the sampling depth of deep soil samples is 150-200cm. After drying, the soil samples are sent to the laboratory to determine the content of heavy metal element lead (Pb) and inert element titanium (Ti);

[0031] S2. Calculate the enrichment coefficient of heavy metal elements in soil samples:

[0032] The enrichment coefficient calculation formula is as follows:

[0033] R=C Pb / B Pb

[0034] In the formula, R Pb is the enrichment coefficient of heavy metal element lead (Pb) in surface soil samples; C Pb is the content of heavy metal element lead (Pb) in surface soil samples; B Pb is the content of heavy metal element lead (Pb) in deep soil samples; R Pb >1 indicates that the heavy metal element lead (Pb) is enriched in the soil, R Pb =1 indicates that there is no enrichment or depletion of elemental lead (Pb) in the soil, R Pb <1 indicates that the heavy metal element lead (Pb) in the soil is depleted. Figure 2 A box plot of the enrichment coefficient of heavy metal element lead (Pb) in soil samples according to an embodiment of the present invention is shown;

[0035] S3. Calculate the migration coefficient of heavy metal elements in soil samples:

[0036] The migration coefficient is calculated as follows:

[0037] M Pb =(C Pb / C Ti ) / (B Pb / B Ti )-1

[0038] Where M Pb is the migration coefficient of heavy metal element lead (Pb) in surface soil samples; C Pb and C Ti are the contents of heavy metal element lead (Pb) and inert element titanium (Ti) in surface soil samples; B Pb and B Ti are the contents of heavy metal element lead (Pb) and inert element titanium (Ti) in deep soil samples; M Pb >0 indicates the net migration of heavy metal element lead (Pb) in the soil, M Pb = 0 indicates that there is no net migration of heavy metal element lead (Pb) in the soil. Pb <0 indicates the net migration of heavy metal element lead (Pb). Figure 3 A box plot of the migration coefficient of the heavy metal element lead (Pb) in the soil sample of the embodiment of the present invention is shown;

[0039] S4. Evaluate the heavy metal pollution of soil samples:

[0040] According to the enrichment factor R Pb >1 and the migration coefficient M Pb >0, the soil samples contaminated by heavy metal element lead (Pb) were screened out, and further enrichment coefficient R PbThe natural breakpoint method was used to divide the pollution degree of soil samples contaminated by heavy metal element lead (Pb) into three levels: light pollution, moderate pollution and heavy pollution. Figure 4 A schematic diagram showing the proportion of each pollution level of the heavy metal element lead (Pb) in the soil sample according to an embodiment of the present invention is shown.

[0041] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A soil heavy metal pollution assessment method based on enrichment migration characteristics, characterized in that: The following steps are involved: S1. Collect soil samples and determine the element content of soil samples: Collect surface and deep soil samples at the same point in the target area, air-dry or bake the soil samples and send them to the laboratory to determine the content of heavy metal elements and inert elements; S2. Calculate the enrichment coefficient of heavy metal elements in soil samples: The enrichment coefficient calculation formula is as follows: R i =C i / B i In the formula, R i is the enrichment coefficient of heavy metal element i in the surface soil sample; C i is the content of heavy metal element i in the surface soil sample; B i is the content of heavy metal element i in deep soil samples; R i >1 indicates that the soil is enriched with heavy metal elements, R i =1 indicates that there is no enrichment or depletion of heavy metal elements in the soil, R i <1 indicates that the soil is depleted of heavy metal elements; S3. Calculate the migration coefficient of heavy metal elements in soil samples: The migration coefficient is calculated as follows: M i =(C i / C j ) / (B i / B j )-1 Where M i is the migration coefficient of heavy metal element i in the surface soil sample; C i and C j are the contents of heavy metal element i and inert element j in surface soil samples; B i and B j are the contents of heavy metal element i and inert element j in deep soil samples; M i >0 indicates a net migration of heavy metal elements i into the soil, M i = 0 indicates that there is no net inflow or outflow of heavy metal element i in the soil, M i <0 indicates a net outflow of heavy metal elements i from the soil; S4. Evaluate the heavy metal pollution of soil samples: According to the enrichment factor R i >1 and the migration coefficient M i >0, the soil samples contaminated by heavy metals were screened out, and further enrichment coefficient R i Classify and grade the contamination levels of soil samples contaminated by heavy metals.

2. A soil heavy metal pollution assessment method based on enrichment migration characteristics according to claim 1, characterized in that: In step S1, the sampling depth of the deep soil sample is below 100 cm, and the inert element is selected as aluminum (Al) or titanium (Ti).

3. The natural karst small watershed soil erosion monitoring system according to claim 1 is characterized in that: In step S4, the classification and grading method adopts the natural breakpoint method.

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