Method for improving heavy metal remediation efficiency of solanum photeinocarpum and improving soil

Abstract

The invention belongs to the technical field of heavy metal contaminated soil remediation, and relates to a method for improving the heavy metal remediation efficiency of solanum photeinocarpum and improving soil. The method comprises the following steps that a modifier is applied to the heavy metal contaminated soil, then solanum photeinocarpum is planted, plants are harvested after the solanum photeinocarpum is mature, and the remediation efficiency and the soil improvement effect of the solanum photeinocarpum are detected; the modifier comprises one or more of tea leaf residues, escargot shell powder and corn straw biochar. The method can promote the growth of the root system of solanum photeinocarpum and the formation of root nodules in a short time, so that the heavy metal extraction amount of the overground part and root of the plant is improved; meanwhile, the physical and chemical properties of the contaminated soil are remarkably improved by adding the modifier, and finally the remediation target of the composite heavy metal contaminated soil is successfully achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of heavy metal contaminated soil remediation, and relates to a method for improving the heavy metal remediation efficiency of Solanum nigrum and improving soil. Background Art

[0002] Heavy metal pollution in soil has become a major issue in global environmental science. Heavy metals such as lead (Pb), cadmium (Cd), arsenic (As) and mercury (Hg) accumulate in soil over a long period of time, posing a serious threat to ecosystems and human health. Traditional soil remediation methods rely on physical and chemical means. Although they can effectively remove pollutants, they are costly and easily cause secondary pollution. Therefore, phytoremediation technology, as a green and environmentally friendly remediation method, is gradually becoming an important choice in the treatment of heavy metal pollution. It uses the natural growth process of plants to absorb and transform pollutants in the soil, thereby achieving soil purification.

[0003] Solanum photeinocarpum is a plant with strong heavy metal tolerance. It can grow in heavy metal polluted environments and effectively accumulate metal elements such as Cd, Pb, Cu, and Zn, showing good remediation potential. Compared with other plants, Solanum photeinocarpum has a shorter growth cycle, can accumulate a large amount of heavy metals in a short period of time, and has excellent drought resistance and salt-alkali tolerance, making it suitable for the remediation of heavily polluted soils. However, whether its roots can form nodules to enhance the remediation effect, especially in the case of complex heavy metal pollution, still needs further exploration.

[0004] It is worth noting that Solanum pauciflorum belongs to the Solanaceae family rather than the Leguminosae family. The symbiotic relationship between legumes and rhizobia is one of the key mechanisms for plants to improve nitrogen utilization efficiency and promote growth. Legumes attract rhizobia by secreting chemical signals such as flavonoids, and induce root cell division through "nodulation factors" to form nodules. Nodules fix nitrogen in the atmosphere into ammonium that can be absorbed by plants, thereby providing important nutritional support for plants in an environment where soil nitrogen is deficient. However, as a member of the Solanaceae family, Solanum pauciflorum does not have this symbiotic ability of legumes, so its root system does not have the characteristics of naturally forming nodules. Although studies have shown that inoculating rhizobia can improve the nitrogen fixation capacity of plants, in actual applications, the effect of rhizobia is restricted by many factors, such as heavy metal soil types, climatic conditions, and differences in plant varieties, which ultimately leads to the research on rhizobia inoculation to promote nodule formation still facing many challenges in agricultural production.

[0005] In view of this, exploring efficient amendments as a new strategy to optimize phytoremediation may provide a more feasible solution. Amendments can not only improve soil structure, but also promote plant root health, thereby increasing the efficiency of plant absorption of heavy metals, opening up a new path for heavy metal pollution control. At the same time, this comprehensive approach also helps to enhance the overall remediation efficiency of the plant-soil system. Summary of the invention

[0006] In view of the above problems existing in the prior art, the present invention provides a method for improving the heavy metal remediation efficiency of Solanum nigrum and improving soil.

[0007] One object of the present invention is achieved by the following technical solutions: A method for improving the heavy metal remediation efficiency of Solanum frutescens and improving soil comprises the following steps: applying an amending agent to heavy metal contaminated soil, then planting Solanum frutescens, harvesting the plants after maturity, and detecting the remediation efficiency of Solanum frutescens and the soil improvement effect.

[0008] Preferably, the improver includes one or more of tea residues, snail shell powder, and corn straw biochar.

[0009] Preferably, the heavy metal contaminated soil is soil contaminated by one or more heavy metals including cadmium (Cd), lead (Pb) and zinc (Zn).

[0010] More preferably, the heavy metal contaminated soil is a composite heavy metal contaminated soil contaminated by cadmium (Cd), lead (Pb) and zinc (Zn).

[0011] Preferably, the Solanum nigrum L. is planted by sowing or transplanting, and its growth cycle is 2 to 3 months. The plants are harvested after maturity. The plants are divided into the aboveground part and the root part.

[0012] Preferably, the amount of the improver added is 200~1000kg / ha.

[0013] More preferably, if the improver is tea residues, the addition amount is 200-500 kg / ha.

[0014] More preferably, if the improver is field snail shell powder, the addition amount is 400-800 kg / ha.

[0015] Further preferably, if the improver is corn straw biochar, the addition amount is 600~1000kg / ha.

[0016] Still more preferably, if the improver is tea residues, the addition amount is 208 kg / ha.

[0017] Still more preferably, if the improver is field snail shell powder, the addition amount is 625 kg / ha.

[0018] Still further preferably, if the modifier is corn straw biochar, the added amount is 833 kg / ha.

[0019] Preferably, the improver is applied before planting Solanum nigrum and is fully mixed with the surface 10-30 cm soil.

[0020] Preferably, the improver is dried, crushed, and passed through a 50-200 mesh sieve to obtain a particle size of 0.1-0.5 mm before application.

[0021] Preferably, the measurement indicators for the detection of the restoration efficiency of Solanum nigrum include: the total amount of heavy metals in the soil, plant yield, plant chlorophyll concentration and plant heavy metal extraction.

[0022] Preferably, the soil improvement effect measurement indicators include: soil pH, organic carbon content, ammonium nitrogen content, nitrate nitrogen content, urease activity and sucrase activity.

[0023] The invention proves the improvement of plant repair efficiency and soil physical and chemical properties by comparing the changes of various indicators before and after planting Solanum nigrum.

[0024] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention provides a method for improving the heavy metal remediation efficiency of Solanum nigrum and improving soil. The method comprises directly sowing or transplanting Solanum nigrum in soil contaminated by heavy metals, and adding modifiers including tea residues, field snail shell powder, and corn straw biochar. The method can promote the root growth and nodule formation of Solanum nigrum in a short period of time, thereby increasing the heavy metal extraction amount of the aboveground part and root of the plant; at the same time, the addition of the modifier significantly improves the physical and chemical properties of the contaminated soil, and finally successfully achieves the goal of remediating the soil contaminated by complex heavy metals.

[0025] 2. The present invention provides a method for improving the heavy metal remediation efficiency of Solanum nigrum and improving the soil. It does not require other complicated treatments, is easy to operate and has low cost. By measuring the accumulation of heavy metals in the roots and aboveground parts of Solanum nigrum plants, it is effectively proved that the remediation efficiency of Solanum nigrum is significantly improved. At the same time, the physical and chemical properties of the soil are also effectively improved, especially in soil contaminated by heavy metals, the remediation effect is remarkable.

[0026] 3. The present invention provides a method for improving the heavy metal remediation efficiency of Solanum nigrum and improving soil. In order to quantitatively evaluate the remediation ability of Solanum nigrum and the soil improvement effect, a series of indicators are used for measurement. The remediation efficiency is determined by comparing the total amount of heavy metals in the soil, the yield of the aboveground part and the root of the plant, and the amount of heavy metal extraction; the soil improvement effect is evaluated by analyzing the changes in soil pH, organic carbon content, ammonium nitrate nitrogen level, and enzyme activity. The data effectively illustrate the significant improvement of the improvement effect of the method of the present invention on heavy metal contaminated soil and the plant remediation performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 The following are photos of the roots of Solanum nigrum plants grown in heavy metal-contaminated soil after being treated in Examples 1 to 3 and Comparative Example 2.

[0028] Figure 2 These are photos of the roots of Bermuda grass plants in heavy metal contaminated soil treated in Comparative Examples 3 to 6.

[0029] Figure 3 The pH diagram of heavy metal contaminated soil after treatment in Examples 1 to 3 and Comparative Example 2.

[0030] Figure 4 The graph shows the content of easily oxidizable organic carbon (ROC) in the heavy metal contaminated soil after treatment in Examples 1 to 3 and Comparative Example 1. Figure 5 Graph showing the content of microbial organic carbon (MBC) in heavy metal contaminated soil treated with Examples 1 to 3 and Comparative Example 1.

[0031] Figure 6 Graph showing the content of ammonium nitrogen (NH4+-N) in heavy metal contaminated soil treated with Examples 1 to 3 and Comparative Example 1.

[0032] Figure 7 This is a graph showing the nitrate nitrogen (NO3--N) content in heavy metal contaminated soil after treatment in Examples 1 to 3 and Comparative Example 1.

[0033] Figure 8 The urease activity diagram in the heavy metal contaminated soil treated by Examples 1 to 3 and Comparative Example 1.

[0034] Fig. 9 The figure is a graph of sucrase activity in heavy metal contaminated soil treated by Examples 1 to 3 and Comparative Example 1.

[0035] Fig.10 This is a graph showing the total amount of heavy metals Cd, Pb, and Zn in the soil after treatment with Example 1 and Comparative Example 1.

[0036] Fig.11This is a graph showing the total amount of heavy metals Cd, Pb, and Zn in the soil after treatment with Example 2 and Comparative Example 1.

[0037] Fig.12 This is a graph showing the total amount of heavy metals Cd, Pb, and Zn in the soil after treatment with Example 3 and Comparative Example 1.

[0038] Fig.13 This is a graph showing the chlorophyll concentration of Solanum nigrum after being treated with Examples 1 to 3 and Comparative Example 2.

[0039] Fig.14 This is a graph showing the aboveground yield of Solanum nigrum after being treated with Examples 1 to 3 and Comparative Example 2.

[0040] Fig.15 This is a diagram of the root yield of Solanum nigrum after being treated with Examples 1 to 3 and Comparative Example 2.

[0041] Fig.16 This is a graph showing the amount of Cd, Pb, and Zn extracted from the aboveground parts of Solanum nigrum after being treated with Example 1 and Comparative Example 2.

[0042] Fig.17 This is a graph showing the amount of Cd, Pb, and Zn extracted from the aboveground parts of Solanum nigrum after treatment with Example 2 and Comparative Example 2.

[0043] Fig.18 This is a graph showing the amount of Cd, Pb, and Zn extracted from the aboveground parts of Solanum nigrum after being treated with Example 3 and Comparative Example 2.

[0044] Fig.19 This is a graph showing the amount of Cd, Pb, and Zn extracted from the roots of Solanum nigrum after treatment with Example 1 and Comparative Example 2.

[0045] Fig. 20 This is a graph showing the amount of Cd, Pb, and Zn extracted from the roots of Solanum nigrum after treatment with Example 2 and Comparative Example 2.

[0046] Fig.21 This is a graph showing the amount of Cd, Pb, and Zn extracted from the roots of Solanum nigrum after treatment with Example 3 and Comparative Example 2. DETAILED DESCRIPTION

[0047] The technical solution of the present invention is further described below in conjunction with specific embodiments and drawings. It should be understood that the specific embodiments described herein are only used to illustrate the present invention and are not used to limit the scope of the present invention. And the drawings used herein are only for better illustrating the disclosed content of the present invention and do not have a limiting effect on the scope of protection. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the claims attached to this application.

[0048] In the following examples and comparative examples, the location is the farmland of Xingping Town, Yangshuo County, Guilin City, Guangxi Zhuang Autonomous Region. Soil pH: 5.47; ammonium nitrogen (NH4+-N) content: 20.62 mg / kg; nitrate nitrogen (NO3--N) content: 8.87 mg / kg; total Cd content: 4.46 mg / kg; total Pb content: 2594.15 mg / kg; total Zn content: 1241.58 mg / kg. The soil is seriously polluted by heavy metals. The contents of Cd, Pb, and Zn in the test field soil are 14.87 times, 37.06 times, and 6.21 times the risk screening values ​​of China's soil pollution (GB 15618-2018), respectively.

[0049] Example 1

[0050] The method for improving the heavy metal remediation efficiency of Solanum pauciflorum and improving soil in this embodiment comprises the following steps: drying tea residues and then crushing them with a grinder, sieving them with a 100-mesh sieve to an average particle size of 0.15 mm to obtain a tea residue improver; applying 208 kg / ha of the tea residue improver to the heavy metal contaminated soil, mixing the tea residues with the soil of about 20 cm above the surface of the heavy metal contaminated soil during application, then planting Solanum pauciflorum by transplanting seedlings, harvesting the plants after they matured for 3 months, recording them as the TD group, and conducting subsequent tests.

[0051] Example 2

[0052] The method for improving the heavy metal remediation efficiency of Solanum pauciflorum and improving soil in this embodiment comprises the following steps: drying snail shells and then crushing them with a grinder, sieving them with a 100-mesh sieve to an average particle size of 0.15 mm to obtain a snail shell powder improver; applying 625 kg / ha of the snail shell powder improver to the heavy metal contaminated soil, mixing the snail shell powder with the soil of about 20 cm above the surface of the heavy metal contaminated soil during application, then planting Solanum pauciflorum by transplanting seedlings, harvesting the plants after they mature for 3 months, recording them as the FS group, and conducting subsequent tests.

[0053] Example 3

[0054] The method for improving the heavy metal remediation efficiency of Solanum pauciflorum and improving soil in this embodiment comprises the following steps: crushing corn straw biochar with a crusher, sieving with a 100-mesh sieve to an average particle size of 0.15 mm, and obtaining a corn straw biochar improver; applying 833 kg / ha of corn straw biochar improver to heavy metal contaminated soil, mixing the corn straw biochar with the soil of about 20 cm above the surface of the heavy metal contaminated soil during application, and then planting Solanum pauciflorum by transplanting seedlings, harvesting the plants after they mature for 3 months, recording them as the CB group, and conducting subsequent tests.

[0055] Comparative Example 1 In this comparative example, heavy metal contaminated soil without plant planting and without amendment was taken as CK0 group, and subsequent testing was carried out.

[0056] Comparative Example 2 In this comparative example, Solanum nigrum was planted in heavy metal contaminated soil by transplanting seedlings, and the plants were harvested after 3 months of maturity, recorded as the CK group, and subsequent tests were carried out.

[0057] Comparative Example 3 This comparative example comprises the following steps: drying the tea residues and then crushing them with a grinder, sieving them with a 100-mesh sieve to an average particle size of 0.15 mm to obtain a tea residue modifier; applying 208 kg / ha of the tea residue modifier to the heavy metal contaminated soil, mixing the tea residues with the soil about 20 cm above the surface of the heavy metal contaminated soil, then planting Bermuda grass, harvesting the plants after they matured for 3 months, recording them as the TD1 group, and conducting subsequent tests.

[0058] Comparative Example 4 This comparative example comprises the following steps: drying the snail shells and then crushing them with a grinder, sieving them with a 100-mesh sieve to an average particle size of 0.15 mm to obtain a snail shell powder improver; applying 625 kg / ha of the snail shell powder improver to the heavy metal contaminated soil, mixing the snail shell powder with the soil about 20 cm above the surface of the heavy metal contaminated soil during application, then planting Bermuda grass, harvesting the plants after they matured for 3 months, recording them as the FS1 group, and conducting subsequent tests.

[0059] Comparative Example 5 This comparative example includes the following steps: crushing the corn straw biochar with a pulverizer, sieving it with a 100-mesh sieve to an average particle size of 0.15 mm, and obtaining a corn straw biochar amendment; applying 833 kg / ha of the corn straw biochar amendment to the heavy metal contaminated soil, and fully mixing the corn straw biochar with the soil of about 20 cm above the surface of the heavy metal contaminated soil during the application, and then planting Bermuda grass, harvesting the plants after they matured for 3 months, recording them as the CB1 group, and conducting subsequent tests.

[0060] Comparative Example 6 In this comparative example, Bermuda grass was planted in heavy metal contaminated soil by transplanting seedlings, and the plants were harvested after 3 months of maturity, recorded as CK1 group, and subsequent tests were carried out.

[0061] The samples to be tested in the above-mentioned embodiments and comparative examples were subjected to relevant tests: the remediation efficiency of Solanum nigrum was measured by the total amount of heavy metals in the soil, the yield of the aboveground and roots of the plants, and the amount of heavy metals extracted; the soil improvement effect was measured by the soil pH, organic carbon content, ammonium nitrate nitrogen, and enzyme activity indicators. Three parallels were set for each group of samples to be tested, and the average value was taken as the final result data. The specific test results are shown in Figures 1 to 21 .

[0062] Figure 1 The following are photos of the roots of Solanum nigrum plants in heavy metal-contaminated soil treated with Examples 1 to 3 and Comparative Example 2. CK represents the treatment of planting only Solanum nigrum, CB represents the treatment of adding corn straw biochar, FS represents the treatment of adding snail shell powder, and TD represents the treatment of adding tea residues. Figure 1 It can be seen that there were no nodules in the roots of Solanum nigrum in the CK group, while the roots of Solanum nigrum with the three additives all showed obvious nodule promotion, especially after the addition of snail shell powder.

[0063] Figure 2 The following are photos of the roots of Bermuda grass plants in heavy metal-contaminated soils treated in Comparative Examples 3 to 6. CK1 represents the treatment of planting only Bermuda grass, CB1 represents the treatment of adding corn straw biochar, FS1 represents the treatment of adding snail shells, and TD1 represents the treatment of adding tea residues. Figure 2 It can be seen that the three improvers have little effect on the root growth of Bermuda grass and will not promote the formation of nodules at the roots of Bermuda grass. This confirms that the improver provided by the present invention is not commonly present in all types of plants.

[0064] Depend on Figure 1~2 It can be seen that the method of the present invention adds tea residues, snail shell powder and corn straw biochar amendments to the soil, which can promote the formation of nodules in Solanum nigrum in a short period of time, and is suitable for promotion in the use of Solanum nigrum to repair Cd-Pb-Zn complex heavy metal contaminated soil.

[0065] Figure 3 The pH diagram of heavy metal contaminated soil after treatment in Examples 1 to 3 and Comparative Example 2. Figure 3 As can be seen from (a), the pH of the treatment with tea residue added was higher than that of the CK treatment, and was significantly increased by 5.8% compared with the CK treatment, indicating that the addition of tea residue can improve the acidic environment of the soil. Figure 3 As can be seen from (b), the pH of the treatment with snail shell powder was higher than that of the CK treatment, and was significantly increased by 9.7% compared with the CK treatment, indicating that the addition of snail shell powder can improve the acidic environment of the soil. Figure 3 As can be seen in (c), the pH of the treatment with corn straw biochar was higher than that of the CK treatment, and was significantly increased by 12.3% compared with the CK treatment, indicating that the addition of corn straw biochar can improve the acidic environment of the soil.

[0066] Figure 4 The graph is a graph of the easily oxidizable organic carbon (ROC) content in the heavy metal contaminated soil treated by Examples 1 to 3 and Comparative Example 1. Figure 4 As can be seen from (a), the ROC of the treatment with tea residue added was higher than that of the CK0 treatment, and was 31.33% higher than that of the CK0 treatment, indicating that the addition of tea residue can increase the ROC content of the soil. Figure 4 As can be seen from (b), the ROC of the treatment with snail shell powder was higher than that of the CK0 treatment, and increased by 67.88% compared with the CK0 treatment, indicating that the addition of snail shell powder can increase the ROC content of soil. Figure 4 As can be seen from (c), the ROC of the treatment with corn straw biochar was higher than that of the CK0 treatment, and was significantly increased by 140.96% compared with the CK0 treatment, indicating that the addition of corn straw biochar can increase the ROC content of soil.

[0067] Figure 5 Figure 2 is a graph showing the content of microbial organic carbon (MBC) in heavy metal contaminated soil treated with Examples 1 to 3 and Comparative Example 1. Figure 5 As can be seen from (a), the soil MBC of the tea residue treatment was higher than that of the CK0 treatment, and was significantly increased by 551.94% compared with the CK0 treatment, indicating that the addition of tea residue can increase the soil MBC content. Figure 5 As can be seen from (b), the MBC of the soil treated with snail shell powder was higher than that of the CK0 treatment, and was significantly increased by 835.48% compared with the CK0 treatment, indicating that the addition of snail shell powder can increase the MBC content of the soil. Figure 5 As can be seen from (c), the soil MBC of the treatment with corn straw biochar was higher than that of the CK0 treatment, and was significantly increased by 895.12% compared with the CK0 treatment, indicating that the addition of corn straw biochar can increase the soil MBC content.

[0068] Figure 6 The figure is a graph showing the ammonium nitrogen (NH4+-N) content in heavy metal contaminated soil treated with Examples 1 to 3 and Comparative Example 1. Figure 6 As can be seen from (a), the NH4+-N content of the treatment with tea residue added is lower than that of the CK0 treatment, and is significantly reduced by 64.75% compared with the CK0 treatment, indicating that the addition of tea residue can promote the absorption of soil NH4+-N by plant roots. Figure 6 As can be seen from (b), the NH4+-N content of the treatment with snail shell powder was lower than that of the CK0 treatment, and was significantly reduced by 64.44% compared with the CK0 treatment, indicating that the addition of snail shell powder can promote the absorption of soil NH4+-N by plant roots. Figure 6 As can be seen from (c), the NH4+-N content of the treatment with corn straw biochar was lower than that of the CK0 treatment, and was significantly reduced by 61.25% compared with the CK0 treatment, indicating that the addition of corn straw biochar can promote the absorption of soil NH4+-N by plant roots.

[0069] Figure 7 Figure 1 is a graph showing the nitrate nitrogen (NO3-N) content in heavy metal-contaminated soil after treatment in Examples 1 to 3 and Comparative Example 1. Figure 7As can be seen from (a), the NO3-N content in the treatment with tea residue addition was higher than that in the CK0 treatment, and was 17.26% higher than that in the CK0 treatment, indicating that the addition of tea residue can convert nitrogen in the soil into more stable NO3-N. Figure 7 As can be seen from (b), the NO3-N content in the treatment with snail shell powder was higher than that in the CK0 treatment, and was significantly increased by 31.27% compared with the CK0 treatment, indicating that the addition of snail shell powder can convert nitrogen in the soil into more stable NO3-N. Figure 7 As can be seen from (c), the NO3-N content in the treatment with corn straw biochar was higher than that in the CK0 treatment, and was significantly increased by 35.37% compared with the CK0 treatment, indicating that the addition of corn straw biochar can convert nitrogen in the soil into more stable NO3-N.

[0070] Figure 8 The urease activity in the heavy metal contaminated soil treated by Examples 1 to 3 and Comparative Example 1 is shown. Figure 8 As can be seen from (a), the urease activity of the treatment with tea residue added was higher than that of the CK0 treatment, and was significantly increased by 645.12% compared with the CK0 treatment, indicating that the addition of tea residue can increase soil urease activity. Figure 8 As can be seen from (b), the urease activity of the treatment with snail shell powder was higher than that of the CK0 treatment, and increased by 557.2% compared with the CK0 treatment, indicating that the addition of snail shell powder can increase soil urease activity. Figure 8 As can be seen from (c), the urease activity of the treatment with corn straw biochar was higher than that of the CK0 treatment, and increased by 580.78% compared with the CK0 treatment, indicating that the addition of corn straw biochar can increase soil urease activity.

[0071] Fig. 9 Figure 2 is a graph showing the activity of sucrase in heavy metal contaminated soil treated with Examples 1 to 3 and Comparative Example 1. Fig. 9 As can be seen from (a), the sucrase activity in the treatment with tea residues added was higher than that in the CK0 treatment, and was 244.94% higher than that in the CK0 treatment, indicating that the addition of tea residues can increase the soil sucrase activity. Fig. 9 As can be seen from (b), the sucrase activity in the treatment with snail shell powder was higher than that in the CK0 treatment, and was significantly increased by 442.31% compared with the CK0 treatment, indicating that the addition of snail shell powder can increase the soil sucrase activity. Fig. 9 As can be seen from (c), the sucrase activity in the treatment with corn straw biochar was higher than that in the CK0 treatment, and was 292.31% higher than that in the CK0 treatment, indicating that the addition of corn straw biochar can increase the soil sucrase activity.

[0072] Fig.10The figure is a graph of the total amount of heavy metals Cd, Pb, and Zn in the soil treated with Example 1 and Comparative Example 1. It can be seen that the content of heavy metals Cd, Pb, and Zn in the treatment with tea residue added in Example 1 is significantly lower than that in the CK0 treatment, and is reduced by 27.23%, 22.65%, and 24.35% respectively compared with the CK0 treatment, indicating that the addition of tea residue can reduce the content of heavy metals Cd, Pb, and Zn in the soil.

[0073] Fig.11 The figure is a graph of the total amount of heavy metals Cd, Pb, and Zn in the soil after treatment with Example 2 and Comparative Example 1. It can be seen that the heavy metal contents of Cd, Pb, and Zn in the treatment with snail shell powder added in Example 2 are significantly lower than those in the CK0 treatment, and are reduced by 25.4%, 24.75%, and 25%, respectively, compared with the CK0 treatment, indicating that the addition of snail shell powder can reduce the heavy metal contents of Cd, Pb, and Zn in the soil.

[0074] Fig.12 The figure is a graph of the total amount of heavy metals Cd, Pb, and Zn in the soil after treatment in Example 3 and Comparative Example 1. It can be seen that the heavy metal contents of Cd, Pb, and Zn in the treatment with corn straw biochar in Example 3 are significantly lower than those in the CK0 treatment, and are reduced by 34.51%, 17.32%, and 17.99%, respectively, compared with the CK0 treatment, indicating that the addition of corn straw biochar can reduce the heavy metal contents of Cd, Pb, and Zn in the soil.

[0075] Fig.13 The chlorophyll concentration of Solanum nigrum L. treated with Examples 1 to 3 and Comparative Example 2 is shown in FIG. Fig.13 As can be seen from (a), the chlorophyll concentration of the treatment with tea residue added was higher than that of the CK treatment, and was 20.35% higher than that of the CK treatment, indicating that the addition of tea residue can increase the chlorophyll concentration of Solanum nigrum. Fig.13 As can be seen from (b), the chlorophyll concentration of the treatment with snail shell powder was higher than that of the CK treatment, and increased by 8.35% compared with the CK treatment, indicating that the addition of snail shell powder can increase the chlorophyll concentration of Solanum nigrum. Fig.13 As can be seen from (c), the chlorophyll concentration of the treatment with corn straw biochar was higher than that of the CK treatment, and increased by 22.17% compared with the CK treatment, indicating that the addition of corn straw biochar can increase the chlorophyll concentration of Solanum nigrum.

[0076] Fig.14 This is a graph showing the aboveground yield of Solanum nigrum after being treated with Examples 1 to 3 and Comparative Example 2. Fig.15 The following is a graph showing the root yield of Solanum nigrum L. treated with Examples 1 to 3 and Comparative Example 2. Fig.14 (a) and Fig.15As can be seen from (a), the dry weight yield of the aboveground part and the root of the treatment with tea residues was higher than that of the CK treatment, and increased by 453.23% and 145% respectively compared with the CK treatment, indicating that the addition of tea residues can increase the dry weight yield of Solanum nigrum. Fig.14 (b) and Fig.15 As can be seen from (b), the dry weight yield of the aboveground part and the root of the treatment with snail shell powder was higher than that of the CK treatment, and increased by 357.68% and 274.42% respectively compared with the CK treatment, indicating that the addition of snail shell powder can increase the dry weight yield of Solanum nigrum. Fig.14 (c) and Fig.15 As can be seen from (c), the aboveground and root dry weight yields of the treatment with corn straw biochar were higher than those of the CK treatment, and increased by 296.36% and 141.41% respectively compared with the CK treatment, indicating that the addition of corn straw biochar can increase the dry weight yield of Solanum nigrum.

[0077] Fig.16 This is a graph showing the amount of Cd, Pb, and Zn extracted from the aboveground parts of Solanum nigrum after being treated with Example 1 and Comparative Example 2. Fig.19 The figure is a graph of the Cd, Pb and Zn extraction from the roots of Solanum pauciflorum treated with Example 1 and Comparative Example 2. It can be seen from the figure that the extraction of heavy metals Cd, Pb and Zn from the aboveground part of the treatment with tea residue in Example 1 is higher than that in the CK treatment, and is increased by 474.30%, 386.28% and 117.69% respectively compared with the CK treatment; the extraction of heavy metals Cd, Pb and Zn from the roots of the treatment with tea residue is higher than that in the CK treatment, and is increased by 89.28%, 84.5% and 126.59% respectively compared with the CK treatment, indicating that the addition of tea residue can increase the extraction of heavy metals Cd, Pb and Zn from the aboveground part and roots of Solanum pauciflorum.

[0078] Fig.17 This is a graph showing the amount of Cd, Pb, and Zn extracted from the aboveground parts of Solanum nigrum after being treated with Example 2 and Comparative Example 2. Fig. 20 The figure is a graph of Cd, Pb and Zn extraction from the roots of Solanum pauciflorum treated with Example 2 and Comparative Example 2. It can be seen from the figure that the extraction of heavy metals Cd, Pb and Zn in the aboveground part of the treatment with snail shell powder in Example 2 is higher than that in the CK treatment, and is increased by 508.3%, 240% and 196.37% respectively compared with the CK treatment; the extraction of heavy metals Cd, Pb and Zn in the roots of the treatment with snail shell powder is higher than that in the CK treatment, and is increased by 201.08%, 100.82% and 209.5% respectively compared with the CK treatment, indicating that the addition of snail shell powder can increase the extraction of heavy metals Cd, Pb and Zn in the aboveground part and roots of Solanum pauciflorum.

[0079] Fig.18 This is a graph showing the amount of Cd, Pb, and Zn extracted from the aboveground parts of Solanum nigrum after being treated with Example 3 and Comparative Example 2. Fig.21The figure is a graph of Cd, Pb, and Zn extraction from the roots of Solanum pauciflorum treated with Example 3 and Comparative Example 2. It can be seen from the figure that the extraction of heavy metals Cd, Pb, and Zn from the aboveground part of the treatment with corn straw biochar in Example 3 is higher than that in the CK treatment, and is increased by 227.97%, 185.26%, and 308.55% respectively compared with the CK treatment; the extraction of heavy metals Cd, Pb, and Zn from the roots of the treatment with corn straw biochar is higher than that in the CK treatment, and is increased by 143.55%, 60.24%, and 147.45% respectively compared with the CK treatment, indicating that the addition of corn straw biochar can increase the extraction of heavy metals Cd, Pb, and Zn from the aboveground part and roots of Solanum pauciflorum.

[0080] In summary, the method of the present invention adds tea residues, snail shell powder and corn straw biochar improvers to heavy metal contaminated soil, which can promote the formation of nodules in Solanum nigrum in a short time and improve the heavy metal remediation efficiency and soil improvement effect, and is very suitable for promotion in Cd-Pb-Zn composite heavy metal contaminated soil.

[0081] The various aspects, embodiments, and features of the present invention should be considered to be illustrative in all aspects and not limiting of the present invention, the scope of which is defined solely by the claims. Other embodiments, modifications, and uses will be apparent to those skilled in the art without departing from the spirit and scope of the claimed invention.

[0082] In the preparation method of the present invention, the order of each step is not limited to the order listed. For those skilled in the art, without creative work, the order of each step is also within the protection scope of the present invention. In addition, two or more steps or actions can be performed simultaneously.

[0083] Finally, it should be noted that the specific embodiments described herein are merely examples of the present invention, and are not intended to limit the implementation methods of the present invention. A person skilled in the art of the present invention may make various modifications or supplements to the specific embodiments described, or replace them in a similar manner. It is not necessary and impossible to provide all examples of all implementation methods here. However, these obvious changes or modifications derived from the essential spirit of the present invention still fall within the scope of protection of the present invention, and interpreting them as any additional limitation is contrary to the spirit of the present invention.

Claims

1. A method for improving the heavy metal remediation efficiency of Solanum nigrum and improving soil, characterized in that: The following steps are involved: Applying an amendment to heavy metal contaminated soil, then planting Solanum nigrum L., harvesting the plants after maturity, and testing the restoration efficiency of Solanum nigrum and the soil improvement effect; the amendment includes one or more of tea residues, field snail shell powder, and corn straw biochar.

2. A method for improving the heavy metal remediation efficiency of Solanum nigrum and improving soil according to claim 1, characterized in that: The heavy metal contaminated soil is soil contaminated by one or more heavy metals including cadmium, lead and zinc.

3. A method for improving the heavy metal remediation efficiency of Solanum nigrum and improving soil according to claim 1, characterized in that: The Solanum nigrum L. is planted by sowing or transplanting, and its growth cycle is 2 to 3 months.

4. A method for improving the heavy metal remediation efficiency of Solanum nigrum and improving soil according to claim 1, characterized in that: The amount of the improver added is 200-1000 kg / ha.

5. A method for improving the heavy metal remediation efficiency of Solanum nigrum and improving soil according to claim 1, characterized in that: If the improver is tea residue, the addition amount is 200-500 kg / ha; If the amendment is field snail shell powder, the addition amount is 400-800 kg / ha; If the amendment is corn straw biochar, the addition amount is 600~1000 kg / ha.

6. A method for improving the heavy metal remediation efficiency of Solanum nigrum and improving soil according to claim 1, characterized in that: If the amendment is tea residue, the addition amount is 208 kg / ha; If the amendment is field snail shell powder, the addition amount is 625 kg / ha; If the amendment is corn straw biochar, the addition amount is 833 kg / ha.

7. The method for improving the heavy metal remediation efficiency of Solanum nigrum and improving soil according to claim 1, characterized in that: The amendment is applied before planting Solanum nigrum and is fully mixed with the surface 10-30 cm soil.

8. The method for improving the heavy metal remediation efficiency of Solanum nigrum and improving soil according to claim 1, characterized in that: The improver is dried, crushed, and passed through a 50-200 mesh sieve to obtain a particle size of 0.1-0.5 mm before application.

9. A method for improving the heavy metal remediation efficiency of Solanum nigrum and improving soil according to claim 1, characterized in that: The measurement indicators for the restoration efficiency detection of Solanum nigrum include: the total amount of heavy metals in the soil, plant yield, plant chlorophyll concentration and plant heavy metal extraction.

10. The method for improving the heavy metal remediation efficiency of Solanum nigrum and improving soil according to claim 1, characterized in that: The soil improvement effect measurement indicators include: soil pH, easily oxidizable organic carbon content, microbial organic carbon content, ammonium nitrogen content, nitrate nitrogen content, urease activity and sucrase activity.

Images