Method for calculating contribution rate of foliage absorption of atmospheric settled heavy metals to crop heavy metal accumulation

Abstract

The invention discloses a method for calculating the contribution rate of foliage absorption of atmospheric settled heavy metals to crop heavy metal accumulation, and belongs to the technical field of heavy metal sources in crops and crop heavy metal pollution prevention and control. According to the method, the contribution rate of the atmospheric sedimentation heavy metal absorbed by the leaves of the crops harvested in different levels of atmospheric pollution areas and different degrees of pollution soil to the accumulation of the heavy metal in the crops can be accurately calculated through a contrast exposure experiment of the atmospheric pollution sedimentation area and the background contrast area and a formula innovated by the method. The technical program and the method are suitable for any farmland area with atmospheric heavy metal pollution, the program operation is simple, the cost is relatively low, the method is simple and convenient to calculate, and the calculated heavy metal accumulation contribution rate of each tissue in the crop body has certain scientificity and reliability; the method can be used as a scientific basis for farmland pollution control and agricultural safety production in heavy metal polluted areas.

Description

Technical Field

[0001] The invention relates to the technical field of heavy metal sources in crops and crop heavy metal pollution prevention and control, and in particular to a method for calculating the contribution rate of atmospheric deposition heavy metals absorbed by leaf surfaces to heavy metal accumulation in crops. Background Art

[0002] With the continuous development of global industrialization, human activities emit a large amount of heavy metals into the atmosphere every year. These heavy metals eventually enter the surface environment through dry and wet atmospheric deposition, bringing serious negative impacts on the ecosystem and human health. Atmospheric deposition of heavy metals is an important external source of heavy metals in farmland; many studies have also shown that these heavy metals have high biological activity and play an important role in the accumulation of heavy metals in crops.

[0003] Atmospheric deposition of heavy metals can be accumulated in crops through two absorption methods: root system and foliar system. Based on this, there is a key issue in the study of the source of heavy metals in crops: in air-polluted areas, are the heavy metals in crops, especially in edible parts, mainly absorbed by the roots (including original heavy metals in the soil and new atmospheric deposition of heavy metals during the crop growing season) or absorbed by the leaves? In addition, for crops grown in soils with different degrees of pollution, how much is the contribution of atmospheric heavy metals absorbed by the leaves to the accumulation of heavy metals in crops? Quantifying the contribution of foliar absorption will help clarify the main pathways for the enrichment of heavy metals in crops in air-polluted areas, and then take targeted measures from the perspective of absorption pathways (foliar or root system) to prevent and control the accumulation of heavy metals in crops, and help regional crop safety production. However, the prior art has not reported a method for obtaining the contribution rate of atmospheric deposition heavy metals absorbed by the leaves to the accumulation of heavy metals in crops. Summary of the invention

[0004] The purpose of the present invention is to provide a method for calculating the contribution rate of atmospheric deposition heavy metals absorbed by leaves to the accumulation of heavy metals in crops, so as to achieve accurate and simple calculation of the contribution of atmospheric deposition heavy metals absorbed by leaves to the accumulation of heavy metals in various ground tissues, especially edible parts, of crops planted in soils polluted to different degrees in air polluted areas.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] The present invention provides a method for calculating the contribution rate of leaf surface absorption of atmospheric deposition heavy metals to crop heavy metal accumulation, comprising the following steps:

[0007] (1) Collecting cultivated soil from background control areas and atmospheric pollution deposition areas to obtain uncontaminated soil and contaminated soil;

[0008] (2) Using the uncontaminated soil and the contaminated soil to plant crops in the background control area, and measuring the heavy metal concentrations MC in the roots and aboveground tissues of the crops respectively root / background , MC aboveground / background The migration coefficient TF of heavy metals in crops in uncontaminated soil and contaminated soil in the background control area was calculated using the formula described in formula I. background ; Using the uncontaminated soil and the contaminated soil to plant crops in the atmospheric pollution deposition area, and measuring the heavy metal concentrations MC in the roots and aboveground tissues of the crops respectively root / atmospheric , MC aboveground / atmospheric The migration coefficient TF of heavy metals in crops in uncontaminated soil and contaminated soil in the atmospheric pollution deposition area is calculated using the formula described in formula II. atmospheric ;

[0009]

[0010] (3) The contribution rate C of leaf surface absorption of atmospheric deposition heavy metals to crop heavy metal accumulation was calculated using the formula described in formula III. A ;

[0011]

[0012] The unit of heavy metal concentration described in formulas I, II and III is mg / kg, based on dry weight.

[0013] (4) Further, simplifying Formula III, the formula described in Formula IV is used to calculate the contribution rate C of leaf surface absorption of atmospheric deposition heavy metals to crop heavy metal accumulation A ;

[0014]

[0015] Preferably, the atmospheric pollution sedimentation area includes an atmospheric pollution medium sedimentation area and an atmospheric pollution high sedimentation area, and step (1) and step (2) are:

[0016] (1) Collecting soil from the cultivated layer of the background control area, the air pollution medium deposition area, and the air pollution high deposition area to obtain unpolluted soil, moderately polluted soil, and heavily polluted soil;

[0017] (2) Using the uncontaminated soil, moderately contaminated soil, and heavily contaminated soil to plant crops in the background control area, and measuring the heavy metal concentrations MC in the roots and aboveground tissues of the crops respectively root / background , MC aboveground / background The migration coefficient TF of heavy metals in crops in uncontaminated soil, moderately contaminated soil, and heavily contaminated soil in the background control area was calculated using the formula described in formula I. backgroundThe uncontaminated soil and the moderately contaminated soil were used to plant and cultivate crops in the atmospheric pollution medium deposition area, and the uncontaminated soil and the severely contaminated soil were used to plant and cultivate crops in the atmospheric pollution high deposition area, and the heavy metal concentrations MC of the roots and aboveground tissues of the crops were measured respectively. root / atmospheric , MC aboveground / atmospheric The formula described in formula II is used to calculate the migration coefficient TF of heavy metals in crops in uncontaminated soil and moderately contaminated soil in the atmospheric pollution precipitation area, and in crops in uncontaminated soil and heavily contaminated soil in the atmospheric pollution high precipitation area. atmospheric .

[0018] Preferably, the cultivated layer of soil in step (1) is the topsoil of 0 to 20 cm.

[0019] Preferably, the background control area is an area more than 35 km away from the source of air pollution, and the high air pollution deposition area and the medium air pollution deposition area are areas within 1 km and 5-7 km away from the source of air pollution, respectively.

[0020] Preferably, the crops in step (2) are crops of the same variety, and the varieties of the crops include grain crops and vegetable crops.

[0021] Preferably, the above-ground tissues in step (2) include stems, leaves, shells, and seeds.

[0022] Beneficial effects of the present invention:

[0023] 1. The present invention provides a method for calculating the contribution rate of atmospheric deposition heavy metals absorbed by leaves to the accumulation of heavy metals in crops. Through a relatively simple comparative exposure experiment in an atmospheric pollution deposition area and a control area and by using the migration coefficient of heavy metals in crop tissues, the contribution of atmospheric deposition heavy metals absorbed by crops through leaves in an atmospheric pollution area to the accumulation of heavy metals in the aboveground tissues of crops, especially in edible parts, can be calculated. The result is accurate and representative, the operation is simple, the cost is low, and it is easy to calculate.

[0024] 2. The present invention helps to clarify the main exposure pathways (foliage or root system) of heavy metals enrichment in crops planted in soils with different degrees of air pollution in areas with different levels of air pollution, and then take targeted measures from the perspective of exposure pathways (foliage or root system) to prevent and control the accumulation of heavy metals in crops. The present invention provides theoretical guidance for the sources of heavy metals in crops and the prevention and control of heavy metal pollution in crops, and provides a scientific theoretical basis for agricultural safety production in some heavy metal polluted areas. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1Schematic diagram of the method in the embodiment of the present invention, wherein the number 1 represents a culture device, 2 represents crops planted in the experiment, 3 represents atmospheric deposition heavy metals, 4 represents the original heavy metals in the contaminated soil, CA is exposed to the control soil treatment in the background control area, CB is exposed to the moderately polluted soil treatment in the background control area, CC is exposed to the severely polluted soil treatment in the background control area, MA is exposed to the control soil treatment in the atmospheric pollution medium deposition area, MB is exposed to the moderately polluted soil treatment in the atmospheric pollution medium deposition area, HA is exposed to the control soil treatment in the atmospheric pollution high deposition area, and HC is exposed to the severely polluted soil treatment in the atmospheric pollution high deposition area;

[0026] Figure 2 is the Cu content in soybean roots;

[0027] Figure 3 is the Cu content in soybean stem;

[0028] Figure 4 is the Cu content in soybean leaves;

[0029] Figure 5 is the Cu content in soybean husk;

[0030] Figure 6 is the Cu content in soybean seeds;

[0031] Figure 7 is the content of Pb in soybean roots;

[0032] Figure 8 is the content of Pb in soybean stem;

[0033] Fig. 9 is the content of Pb in soybean leaves;

[0034] Fig.10 is the content of Pb in soybean husk;

[0035] Fig.11 is the content of Pb in soybean seeds;

[0036] Fig.12 is the Cd content in soybean roots;

[0037] Fig.13 is the Cd content in soybean stems;

[0038] Fig.14 is the Cd content in soybean leaves;

[0039] Fig.15 is the Cd content in soybean husk;

[0040] Fig.16 is the Cd content in soybean seeds;

[0041] Fig.17 is the content of Cu in the roots of Chinese cabbage;

[0042] Fig.18 is the Cu content in the aboveground tissue of Chinese cabbage;

[0043] Fig.19 is the Cd content in the roots of Chinese cabbage;

[0044] Fig. 20 is the Cd content in the aboveground tissues of Chinese cabbage;

[0045] Fig.21 is the Pd content in the roots of Chinese cabbage;

[0046] Fig. 22 is the Pd content in the aboveground tissues of Chinese cabbage. DETAILED DESCRIPTION

[0047] The present invention provides a method for calculating the contribution rate of leaf surface absorption of atmospheric deposition heavy metals to crop heavy metal accumulation, comprising the following steps:

[0048] (1) Collecting cultivated soil from background control areas and atmospheric pollution deposition areas to obtain uncontaminated soil and contaminated soil;

[0049] (2) Using the uncontaminated soil and the contaminated soil to plant crops in the background control area, and measuring the heavy metal concentrations MC in the roots and aboveground tissues of the crops respectively root / background , MC aboveground / background The migration coefficient TF of heavy metals in crops in uncontaminated soil and contaminated soil in the background control area was calculated using the formula described in formula I. background ; Using the uncontaminated soil and the contaminated soil to plant crops in the atmospheric pollution deposition area, and measuring the heavy metal concentrations MC in the roots and aboveground tissues of the crops respectively root / atmospheric , MC aboveground / atmospheric The migration coefficient TF of heavy metals in crops in uncontaminated soil and contaminated soil in the atmospheric pollution deposition area is calculated using the formula described in formula II. atmospheric ;

[0050]

[0051] (3) The contribution rate C of leaf surface absorption of atmospheric deposition heavy metals to crop heavy metal accumulation was calculated using the formula described in formula III. A ;

[0052]

[0053] The unit of heavy metal concentration described in formulas I, II and III is mg / kg, based on dry weight.

[0054] (4) Further, simplifying Formula III, the formula described in Formula IV is used to calculate the contribution rate C of leaf surface absorption of atmospheric deposition heavy metals to crop heavy metal accumulation A ;

[0055]

[0056] In order to accurately grasp the contribution rate of atmospheric deposition heavy metals absorbed by the leaves of crops harvested from atmospheric pollution deposition areas of different degrees and polluted soils of different degrees to the accumulation of heavy metals in crops, the atmospheric pollution deposition areas in the present invention include atmospheric pollution medium deposition areas and atmospheric pollution high deposition areas, and then steps (1) and (2) are specifically as follows:

[0057] (1) Collecting soil from the cultivated layer of the background control area, the air pollution medium deposition area, and the air pollution high deposition area to obtain unpolluted soil, moderately polluted soil, and heavily polluted soil;

[0058] (2) Using the uncontaminated soil, moderately contaminated soil, and heavily contaminated soil to plant crops in the background control area, and measuring the heavy metal concentrations MC in the roots and aboveground tissues of the crops respectively root / background , MC aboveground / background The migration coefficient TF of heavy metals in crops in uncontaminated soil, moderately contaminated soil, and heavily contaminated soil in the background control area was calculated using the formula described in formula I. background The uncontaminated soil and the moderately contaminated soil were used to plant and cultivate crops in the atmospheric pollution medium deposition area, and the uncontaminated soil and the severely contaminated soil were used to plant and cultivate crops in the atmospheric pollution high deposition area, and the heavy metal concentrations MC of the roots and aboveground tissues of the crops were measured respectively. root / atmospheric , MC aboveground / atmospheric The formula described in formula II is used to calculate the migration coefficient TF of heavy metals in crops in uncontaminated soil and moderately contaminated soil in the atmospheric pollution precipitation area, and in crops in uncontaminated soil and heavily contaminated soil in the atmospheric pollution high precipitation area. atmospheric .

[0059] In the present invention, the cultivated soil layer in step (1) is the topsoil of 0 to 20 cm, more preferably 0 to 15 cm. The background control area is an area more than 35 km away from the source of air pollution in the downwind direction, and the high air pollution deposition area and the medium air pollution deposition area are areas within 1 km away from the source of air pollution in the downwind direction and 5-7 km downwind, respectively. The source of air pollution is preferably a point source of pollution emission, such as a non-ferrous metal smelter.

[0060] Within the regional scope defined in the present invention, the soil types in the medium atmospheric pollution deposition area, the high atmospheric pollution deposition area and the background control area are all the main types of soil in the study area, namely, hydroponic anthropogenic soil. Except for the obvious differences in heavy metal concentrations, the soil physical and chemical properties of the three areas are similar, and the slight differences are within a reasonable range, which better reflects the basic situation of the physical and chemical properties of the soil in the study area. The experimental results have good practical applicability.

[0061] In the present invention, the crops were watered with tap water throughout the crop growth period. The heavy metal concentrations in tap water were all low (Cu<0.1μg / L, Cd<0.01μg / L and Pb<0.01μg / L). The heavy metal flux introduced into the research system by crop watering was much lower than the atmospheric deposition input, and its effect on the accumulation of various heavy metals (including Cd, Pb, Cu) in crops was negligible.

[0062] After obtaining uncontaminated soil and moderately and severely contaminated soil, the present invention uses the three soils to plant and cultivate crops in the background control area, and respectively determines the heavy metal concentrations MC of the roots and aboveground tissues of the crops in the three soil treatments. root / background , MC aboveground / background The migration coefficient TF of heavy metals in the crops harvested from the three soils in the background control area was calculated using the formula described in formula I. background ;

[0063]

[0064] After obtaining uncontaminated soil and moderately contaminated soil, the present invention uses the two soils to plant and cultivate crops in the atmospheric pollution precipitation area, and respectively measures the heavy metal concentrations MC of the roots and aboveground tissues of the crops under the two soil treatments. root / atmospheric , MC aboveground / atmospheric After obtaining uncontaminated soil and heavily contaminated soil, the present invention uses the two soils to plant and cultivate crops in areas with high atmospheric pollution deposition, and respectively determines the heavy metal concentrations MC in the roots and aboveground tissues of the crops under the two soil treatments. root / atmospheric , MC aboveground / atmospheric Then, the formula described in Formula II is used to calculate the migration coefficient TF of heavy metals in crops grown in the middle and high sedimentation areas when using the same soil scenario as the background area. atmospheric ;

[0065]

[0066] Then, based on the assumption that the same type of soil (such as uncontaminated soil or moderately or severely contaminated soil) is exposed to the atmospheric pollution deposition area and the control area, the migration coefficient TF of the crops planted in the soil through root absorption of the original heavy metals in the soil and then to the aboveground part and the migration coefficient TF of the crops planted in the soil through root absorption of the new atmospheric deposition heavy metals in the soil to the aboveground part are the same.

[0067] Under this hypothetical scenario, the present invention uses the formula described in Formula III to calculate the contribution rate C of leaf surface absorption of atmospheric deposition heavy metals to crop heavy metal accumulation. A ;

[0068]

[0069] The unit of heavy metal concentration described in formulas I, II and III is mg / kg, based on dry weight.

[0070] Subsequently, Formula III was further simplified and the contribution rate C of leaf surface absorption of atmospheric deposition heavy metals to crop heavy metal accumulation was calculated using the formula described in Formula IV: A ;

[0071]

[0072] In the present invention, when formulas I, II, III, and IV are used for calculation, the plants are crops of the same variety. The varieties of the crops include food crops and vegetable crops; the food crops are preferably dryland crops, and more preferably soybeans; the vegetable crops are preferably leafy vegetables and fruit vegetables; the leafy vegetables preferably include Chinese cabbage and lettuce; the fruit vegetables are preferably peppers.

[0073] In the present invention, the crop tissue is tissue of the same variety of crops, and the above-ground tissue includes one or more of stems, leaves, shells and grains.

[0074] In the present invention, the device for planting and cultivating crops is preferably a culture box, and the material of the culture box is preferably PP polypropylene, and the size is preferably 0.60m (length) × 0.45m (width) × 0.35m (height). The culture box is preferably placed on a stainless steel frame about 1.5m from the ground to avoid splashing water and soil from contaminating the culture device during heavy rain. In addition, considering that there is more rain in the experimental area, a leaching device is set at the bottom of the culture box (filled with 10mm thick acid washed quartz + 40 mesh nylon mesh + a small hole with a diameter of 3cm at the bottom of the box) to drain excess water as soon as possible during the rainy season to ensure the normal growth of crops.

[0075] In the present invention, there are no special requirements or restrictions on the devices and conditions for planting and cultivating crops, as long as the crops are guaranteed to grow normally according to their growth habits.

[0076] In the present invention, sampling begins after the crops mature, and the heavy metal content of the samples is determined. The present invention has no special restrictions on the method for determining the heavy metal content in crop tissues, and conventional methods in the art can be used; in the specific implementation process of the present invention, conventional methods are first used to dry, grind, and sieve the plant tissue through a 100-mesh sieve to obtain a homogeneous sample, and then the heavy metal content in the crop tissue is determined by the method of the national standard GB 5009.15-2014 "National Food Safety Standard Determination of Cadmium in Food".

[0077] In the embodiment of the present invention, the method is set as shown in the schematic diagram Figure 1 , where the number 1 represents the culture device, 2 represents the crops planted in the experiment, 3 represents the atmospheric deposition heavy metals, 4 represents the original heavy metals in the contaminated soil, CA is the control soil treatment exposed to the background control area, CB is the moderately polluted soil treatment exposed to the background control area, CC is the highly polluted soil treatment exposed to the background control area, MA is the control soil treatment exposed to the atmospheric pollution medium deposition area, MB is the moderately polluted soil treatment exposed to the atmospheric pollution medium deposition area, HA is the control soil treatment exposed to the atmospheric pollution high deposition area, and HC is the severely polluted soil treatment exposed to the atmospheric pollution high deposition area.

[0078] The technical solution of the present invention will be described clearly and completely below in conjunction with the embodiments of the present invention. However, the embodiments described in the present invention are only a part of the embodiments of the present invention, and other changes, modifications, substitutions, combinations, and simplified embodiments that do not deviate from the spirit and principle of the present invention should all be equivalent replacement methods and are included in the protection scope of the present invention.

[0079] Example 1: Soybean planting experiment under different air pollution conditions

[0080] This example was carried out in the surrounding area of ​​a copper smelter in northeastern Jiangxi Province, my country. The region has a typical subtropical humid monsoon climate, with an average annual temperature of 16-20°C and an average annual precipitation of 1720 mm. The prevailing wind direction is northeasterly all year round, with an average annual wind speed of 1.20 m / s. The main soil types in the region include red soil and hydroponic anthropogenic soil.

[0081] In this embodiment, the high atmospheric pollution deposition area is selected at 1 km southwest of the copper smelter, and the soil in this area is heavily polluted soil; the medium atmospheric pollution deposition area is selected at 6 km southwest of the copper smelter, and the soil in this area is moderately polluted soil; the background control area is selected at 35 km southwest of the copper smelter, and the soil is unpolluted control soil. The physical and chemical properties and heavy metal content of the soil in the three areas are shown in Table 1 below.

[0082] Table 1 Physical and chemical properties and heavy metal content of the test soil

[0083]

[0084] The data in Table 1 show that the soil types in the three regions are the main types of soil in the study area, namely hydroponic anthropogenic soil. Except for the obvious differences in heavy metal concentrations, the soil physical and chemical properties of the three regions are similar, and the slight differences between them reflect the basic situation of the soil physical and chemical properties in the study area within a reasonable range. The experimental results have good practical applicability.

[0085] This example conducts a soil-crop comparative exposure study in an area with high atmospheric pollution deposition, an area with medium atmospheric pollution deposition, and a background control area. The experiment includes 6 treatment groups, namely, a control soil treatment group (CA) exposed to a background control area, a moderately polluted soil treatment group (CB) exposed to a background control area, a highly polluted soil treatment group (CC) exposed to a background control area, a control soil treatment group (MA) exposed to a medium atmospheric pollution deposition area, a moderately polluted soil treatment group (MB) exposed to a medium atmospheric pollution deposition area, a control soil treatment group (HA) exposed to a high atmospheric pollution deposition area, and a heavily polluted soil treatment group (HC) exposed to a high atmospheric pollution deposition area.

[0086] The soybean variety selected was Gandou No. 6, the main local variety, and four soybeans were planted in each incubator. The size of the incubator was 0.60m (length) × 0.45m (width) × 0.35m (height), and each incubator was filled with 100kg of test soil. The incubator was placed on a stainless steel frame about 1.5m from the ground to prevent splashes of water and soil from contaminating the incubator during heavy rain. In addition, considering that there was a lot of rain in the experimental area, a leaching device was set at the bottom of the incubator (filled with 10mm thick acid-washed quartz + 40 mesh nylon mesh + a small hole with a diameter of 3cm at the bottom of the box) to drain excess water as soon as possible during the rainy season to ensure the normal growth of soybean plants. Tap water was used for watering throughout the soybean growth cycle. The concentration of heavy metals in tap water was low (Cu<0.1μg / L, Cd<0.01μg / L and Pb<0.01μg / L). The heavy metal flux introduced into the research system by crop watering was much lower than the atmospheric deposition input, and its effect on the accumulation of various heavy metals (including Cd, Pb, and Cu) in soybean was negligible.

[0087] Sampling began after soybeans matured, and the collected soybean plants were divided into roots, stems, leaves, shells and seeds. Then the plant tissues were washed with tap water and deionized water to remove soil and dust adhering to the surface. The plant tissues were then dried, ground and passed through a 100-mesh sieve to obtain homogenous samples. Then, the heavy metal content in soybean tissues was determined using the method of the national standard GB 5009.15-2014 "Determination of Cadmium in Foods in National Food Safety Standards", that is, a 9:1 mixture of nitric acid and perchloric acid was first cold digested overnight, then heated to 160°C for digestion for 3 hours, and then the heavy metal content was determined by ICP-MS. In addition, blank samples and spinach standard substances (GBW07442) were used for quality control, and the recovery rate reached 97-103%.

[0088] The test results can be found in Figure 2 to Figure 16 ,in, Figure 2 is the Cu content in soybean roots; Figure 3 is the Cu content in soybean stem; Figure 4 is the Cu content in soybean leaves; Figure 5 is the Cu content in soybean husk; Figure 6 is the Cu content in soybean seeds; Figure 7 is the Pb content in soybean roots; Figure 8 is the Pb content in soybean stem; Fig. 9 is the Pb content in soybean leaves; Fig.10 is the Pb content in soybean husk; Fig.11 is the Pb content in soybean seeds; Fig.12 is the Cd content in soybean roots; Fig.13 is the Cd content in soybean stem; Fig.14 is the Cd content in soybean leaves; Fig.15 is the Cd content in soybean husk; Fig.16 is the Cd content in soybean seeds. The results show that when the uncontaminated soil was exposed to the atmospheric pollution deposition area, the heavy metal content in each soybean tissue increased significantly; and the increase rate of the aboveground tissue was greater than that of the root. When the contaminated soil was replaced with the background control area, the heavy metal content in each soybean tissue decreased significantly; and the decrease in the aboveground tissue was greater than that of the root. These results indicate that atmospheric deposition of heavy metals during the crop growth period has an important contribution to the accumulation of heavy metals in soybean plants; it also potentially suggests that leaf absorption may have an important influence on the accumulation of heavy metals in soybean plants.

[0089] According to the calculation formula of the contribution rate of heavy metals deposited by leaves to the accumulation of heavy metals in soybeans in the present invention, the following Table 2 can be obtained. C1, C2, C3, and C4 are contribution rates of leaf absorption. C1 represents the contribution rate of heavy metals deposited by leaves to the accumulation of heavy metals in soybeans when the soil in the background control area is exposed to moderately polluted atmosphere (i.e., the middle deposition area of ​​atmospheric pollution); C2 represents the contribution rate of heavy metals deposited by leaves to the accumulation of heavy metals in soybeans when the soil in the background control area is exposed to high-concentration polluted atmosphere (i.e., the high deposition area of ​​atmospheric pollution); C3 represents the contribution rate of heavy metals deposited by leaves to the accumulation of heavy metals in soybeans when moderately polluted soil is exposed to moderately polluted atmosphere (i.e., the middle deposition area of ​​atmospheric pollution); C4 represents the contribution rate of heavy metals deposited by leaves to the accumulation of heavy metals in soybeans when heavily polluted soil is exposed to high-concentration polluted atmosphere (i.e., the high deposition area of ​​atmospheric pollution). The results show that for the three heavy metals (Cu, Pb, and Cd), the leaf absorption of atmospheric deposition heavy metals has a high contribution to the accumulation of heavy metals in various soybean tissues. For stems, the contribution value is 15% to 62%; for leaves, the contribution value is 16% to 69%; for shells, the contribution value is 19% to 75%; for seeds, the contribution value is 20% to 51%. As the edible part, the results of seeds are more worthy of our attention. When soybeans were planted in the control area and exposed to high concentrations of polluted air (i.e., high atmospheric pollution deposition areas), the contribution of foliar absorption of atmospheric deposition Cd to the accumulation of Cd in soybean seeds reached 51%, indicating that foliar absorption is the main way for soybean seeds to enrich Cd in this scenario. For other metals and other treatment groups, the contribution of foliar absorption cannot be ignored. Further analysis of these results shows that when soybeans are exposed to medium concentrations of polluted air, that is, areas far away from pollution point sources, the contribution rate of foliar absorption to the accumulation of heavy metals (Cu, Pb, Cd) in soybean seeds is lower than or partially equivalent to that of soybeans exposed to high concentrations of polluted air (i.e., high atmospheric pollution deposition areas), but its value still reaches 20% to 42%. This indicates that under this exposure scenario, foliar absorption still has a high impact on the accumulation of heavy metals in crops.

[0090] Table 2 Contribution of heavy metals absorbed by leaves to heavy metal accumulation in soybean

[0091]

[0092] Based on the above results, we propose that in air pollution areas, whether in high-concentration air pollution areas close to emission sources or in medium-concentration air pollution areas with larger cultivated land areas far from emission sources, taking measures to control the accumulation of heavy metals in crops from the perspective of leaf absorption may have important practical significance. In the future, research on regulating leaf absorption should be strengthened. For example, from the perspective of the absorption process of leaf exposure, some stomatal regulators and leaf barrier agents should be studied more; from the perspective of the transport process, low-accumulation crop varieties under leaf exposure scenarios and transport proteins that regulate heavy metal accumulation should be screened and identified.

[0093] Example 2: Experiment on growing Chinese cabbage under different air pollution conditions

[0094] The selection of the test area, the design of the comparative exposure test, the pretreatment of plant samples, the determination method of the heavy metal content of the samples, etc. are the same as those in Example 1 and will not be repeated here. The variety of the pakchoi planting experiment was selected. The pakchoi-youdonger, which is widely planted in the study area, was planted at a density of 9 plants per culture box.

[0095] The results of this example can be found in Figure 17 to Figure 22 , Fig.17 is the Cu content in the roots of Chinese cabbage; Fig.18 is the Cu content in the aboveground tissue of Chinese cabbage; Fig.19 is the Cd content in the roots of Chinese cabbage; Fig. 20 is the Cd content in the aboveground tissues of Chinese cabbage; Fig.21 is the Pd content in the roots of Chinese cabbage; Fig. 22 is the Pd content in the aboveground tissues of Chinese cabbage. The results showed that when the uncontaminated soil was exposed to the atmospheric pollution deposition area, the heavy metal content in the aboveground tissues and root tissues of Chinese cabbage increased significantly; when the contaminated soil was replaced in the background control area, the heavy metal content in the aboveground tissues and root tissues of Chinese cabbage decreased significantly; and the increase and decrease of the heavy metal content in the aboveground tissues were significantly higher than that in the root tissues.

[0096] According to the calculation formula of the contribution rate of heavy metal accumulation absorbed by plant leaves in the present invention, the following Table 3 can be obtained. C1, C2, C3, and C4 are contribution rates of leaf absorption. C1 represents the contribution rate of heavy metals deposited by leaves to the accumulation of heavy metals in soybeans when the soil in the background control area is exposed to moderately polluted atmosphere (i.e., the middle deposition area of ​​atmospheric pollution); C2 represents the contribution rate of heavy metals deposited by leaves to the accumulation of heavy metals in soybeans when the soil in the background control area is exposed to high-concentration polluted atmosphere (i.e., the high deposition area of ​​atmospheric pollution); C3 represents the contribution rate of heavy metals deposited by leaves to the accumulation of heavy metals in soybeans when moderately polluted soil is exposed to moderately polluted atmosphere (i.e., the middle deposition area of ​​atmospheric pollution); C4 represents the contribution rate of heavy metals deposited by leaves to the accumulation of heavy metals in soybeans when heavily polluted soil is exposed to high-concentration polluted atmosphere (i.e., the high deposition area of ​​atmospheric pollution). The results show that for three heavy metals (Cu, Pb, Cd), the leaf surface absorption of atmospheric deposition heavy metals has a high contribution to the accumulation of heavy metals in the edible parts of Chinese cabbage, with a contribution value of 13% to 73%. Among them, the contribution value of exposure to high-concentration polluted air (i.e., high atmospheric pollution deposition area) is 22% to 73%, and the contribution value of exposure to medium-concentration polluted air is also 13% to 48%. These results and the results of Example 1 show that in air-polluted areas, not only for food crops-soybeans, but also for vegetable crops, the leaf surface absorption of atmospheric deposition heavy metals has a high contribution to the accumulation of heavy metals in the edible parts of vegetables.

[0097] Table 3 Contribution of heavy metals absorbed by leaves to heavy metal accumulation in Chinese cabbage

[0098]

[0099] The above is only a preferred embodiment of the present invention, and the present invention is not limited to the above embodiments. On the basis of the technical solution disclosed in the present invention, technicians in this field can also make several improvements and modifications based on the disclosed technical content without departing from the principle of the present invention. These improvements and modifications are all within the protection scope of the present invention.

Claims

1. A method for calculating the contribution rate of leaf surface absorption of atmospheric deposition heavy metals to crop heavy metal accumulation, characterized in that: The following steps are involved: (1) Collecting cultivated soil from background control areas and atmospheric pollution deposition areas to obtain uncontaminated soil and contaminated soil; (2) Using the uncontaminated soil and the contaminated soil to plant crops in the background control area, and measuring the heavy metal concentrations MC in the roots and aboveground tissues of the crops respectively root / background , MC aboveground / background The migration coefficient TF of heavy metals in crops in uncontaminated soil and contaminated soil in the background control area was calculated using the formula described in formula I. background ; Using the uncontaminated soil and the contaminated soil to plant crops in the atmospheric pollution deposition area, and measuring the heavy metal concentrations MC in the roots and aboveground tissues of the crops respectively root / atmospheric , MC aboveground / atmospheric The migration coefficient TF of heavy metals in crops in uncontaminated soil and contaminated soil in the atmospheric pollution deposition area is calculated using the formula described in formula II. atmospheric ; (3) The contribution rate C of leaf surface absorption of atmospheric deposition heavy metals to crop heavy metal accumulation was calculated using the formula described in formula III. A ; The unit of heavy metal concentration described in formulas I, II and III is mg / kg, based on dry weight. (4) Further, simplifying Formula III, the formula described in Formula IV is used to calculate the contribution rate C of leaf surface absorption of atmospheric deposition heavy metals to crop heavy metal accumulation A ; 2. The method for calculating the contribution rate of leaf surface absorption of atmospheric deposition heavy metals to crop heavy metal accumulation according to claim 1, characterized in that: The air pollution sedimentation area includes an air pollution medium sedimentation area and an air pollution high sedimentation area, and steps (1) and (2) are: (1) Collecting soil from the cultivated layer of the background control area, the air pollution medium deposition area, and the air pollution high deposition area to obtain unpolluted soil, moderately polluted soil, and heavily polluted soil; (2) Using the uncontaminated soil, moderately contaminated soil, and heavily contaminated soil to plant crops in the background control area, and measuring the heavy metal concentrations MC in the roots and aboveground tissues of the crops respectively root / background , MC aboveground / background The migration coefficient TF of heavy metals in crops in uncontaminated soil, moderately contaminated soil, and heavily contaminated soil in the background control area was calculated using the formula described in formula I. background The uncontaminated soil and the moderately contaminated soil were used to plant and cultivate crops in the atmospheric pollution medium deposition area, and the uncontaminated soil and the severely contaminated soil were used to plant and cultivate crops in the atmospheric pollution high deposition area, and the heavy metal concentrations MC of the roots and aboveground tissues of the crops were measured respectively. root / atmospheric , MC aboveground / atmospheric The formula described in formula II is used to calculate the migration coefficient TF of heavy metals in crops in uncontaminated soil and moderately contaminated soil in the atmospheric pollution precipitation area, and in crops in uncontaminated soil and heavily contaminated soil in the atmospheric pollution high precipitation area. atmospheric .

3. The method for calculating the contribution rate of leaf surface absorption of atmospheric deposition heavy metals to crop heavy metal accumulation according to claim 1, characterized in that: The tillage layer soil in step (1) is the topsoil of 0 to 20 cm.

4. The method for calculating the contribution rate of leaf surface absorption of atmospheric deposition heavy metals to crop heavy metal accumulation according to claim 2, characterized in that: The background control area is an area more than 35 km away from the source of air pollution, and the high air pollution deposition area and the medium air pollution deposition area are areas within 1 km and 5-7 km away from the source of air pollution respectively.

5. The method for calculating the contribution rate of leaf surface absorption of atmospheric deposition heavy metals to crop heavy metal accumulation according to claim 1, characterized in that: The crops in step (2) are crops of the same variety, and the varieties of the crops include grain crops and vegetable crops.

6. The method for calculating the contribution rate of leaf surface absorption of atmospheric deposition heavy metals to crop heavy metal accumulation according to claim 1, characterized in that: The above-ground tissues in step (2) include stems, leaves, shells, and seeds.

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