CN112930743B

CN112930743B - Method for restoring soil of ionic rare earth abandoned mining area

Info

Publication number: CN112930743B
Application number: CN202110190062.3A
Authority: CN
Inventors: 张萌; 王启沛; 冯兵; 姚娜; 师艳丽; 李铭书; 吴俊伟; 刘足根; 吴少林
Original assignee: Jiangxi Academy Of Eco Environmental Science And Planning
Current assignee: Jiangxi Academy Of Eco Environmental Science And Planning
Priority date: 2021-02-18
Filing date: 2021-02-18
Publication date: 2023-02-17
Anticipated expiration: 2041-02-18
Also published as: CN112930743A

Abstract

The invention provides a method for restoring Cd pollution of soil in an ionic rare earth abandoned mining area, and relates to the technical field of soil restoration. The restoration method provided by the invention jointly restores the ionic rare earth abandoned mine area soil by using the pioneer plant promoting abandoned rare earth tailings and the indigenous fungi, has the characteristics of high plant restoration success rate, excellent effect, simple and convenient technical process, easiness in construction, capability of obviously reducing the content of Cd in the soil, water and soil loss rate and the like, is lower in cost, attractive and safe, is easy to popularize and apply compared with similar methods, and has huge application prospect and market demand. In the embodiment of the invention, the ionic rare earth abandoned mine area in the southern rainy region is inoculated with the bacterial liquid of trichoderma and/or penicillium oxalicum, and the herbaceous or shrub plant seeds are sowed in holes, so that Cd in soil can be absorbed obviously, the biomass of plants can be improved, the vegetation ecological restoration effect is good, and the method is suitable for rapidly treating Cd pollution of the rare earth tailing abandoned land in the southern rainy region.

Description

Method for restoring soil of ionic rare earth abandoned mining area

Technical Field

The invention belongs to the technical field of soil remediation, and particularly relates to a method for remediating ionic rare earth abandoned mine soil.

Background

The ionic rare earth is a national strategic resource, has non-regenerability, and is widely applied to the fields of national defense construction and high-tech technology. The ionic rare earth in the Gannan region of Jiangxi province is rich in resources, is called the rare earth kingdom of China, and 30 percent of ionic rare earth in the Gannan city of Jiangxi province nationwide is owned by Jiangxi province, so that the ionic rare earth is concerned at present at home and abroad. Gannan rare earth mining begins in the 70-80 years of the 20 th century and approximately comprises 3 mining processes of pond leaching, heap leaching and in-situ ore leaching. The rare earth mining creates high benefits and simultaneously causes a series of ecological environment problems of vegetation and land resource destruction, water and soil pollution and the like. Especially, the problem of water and soil pollution in mining areas and the periphery is the most serious when the in-situ leaching process is used for extracting rare earth elements in the 90 s of the 20 th century. The field survey finds that Gannan is seriously affected by the mining of the ionic rare earth mine, the soil property is loose, the soil desertification is serious, and the phenomenon of grass growth occurs, so that the serious water and soil environment pollution problem is caused, and the regional agricultural and social development is seriously restricted and hindered. Therefore, aiming at the damage of the mining of the ionic rare earth ore to the surrounding environment, the ecological reconstruction of the Gannan ionic rare earth tailing area is urgently developed.

Due to the reasons that the tailing sand matrix of the ionic rare earth abandoned mine area is extremely barren, low in organic matter content, low in sticky particle content, poor in texture, acidic, large in salt residue, lack of aggregates, poor in structure, poor in fertility preservation and water retention capacity and the like, water and soil loss is easily caused in the rare earth abandoned mine in south Jiangnan in the rainstorm season, and therefore a large number of abandoned side slopes are generated, the slope is unstable, the ground surface is bare, and vegetation is lack to cause serious geological disasters such as collapse, landslide and the like. Researches on the chemical forms and migration transformation of heavy metals in a certain rare earth mining area in south show that the pollution of heavy metals Pb, cd and Zn around the mining area is serious, and the Pb, cd and Zn are easy to generate secondary pollution due to the large amount of ammonium ions, wherein the content of Cd in the tailing water is up to 3mg/L, and the human health and safety of the mining area are seriously threatened; the contents of Cd in the abandoned land, the soil taking place and the heap leaching pond of the rare earth tailings area of a certain ionic type in Fujian province are 141 times, 97 times and 69 times of the background value of the soil in the Fujian province respectively, the average content of rare earth elements in the soil of the planting land near the mining area is also higher than the background value of the Fujian province, and the content of Cd exceeds the secondary standard of the soil environmental quality by more than ten times. The evaluation of the risk of the soil in certain mining area of Gannan province shows that: the heavy metal total enrichment angle is evaluated, cd in the soil in the area is from severe pollution to extreme pollution, pb is from moderate pollution to severe pollution, and the average pollution degree is that Cd is greater than Pb; from the morphological evaluation, the Cd and Pb in the area have light pollution to heavy pollution, wherein the Cd content can reach 10mg/kg at most, and the health of nearby animals, plants and human beings is seriously influenced. Therefore, the pollution of the heavy metal Cd in the rare earth mining area needs to be quickly treated.

The existing ion type waste rare earth mine tailing sand matrix repairing technology is less due to the reasons that the south waste ion type rare earth tailing sand matrix is extremely barren, low in organic matter content, low in sticky particle content, poor in texture, lack of aggregates, poor in structure, poor in fertilizer retention capacity and the like. The current restoration method mainly comprises in-situ treatment and ex-situ treatment, wherein the in-situ treatment is disclosed in Chinese patent with publication number CN102640590A (application number 201210125698.0) and adopts arbuscular mycorrhizal fungi technology to restore vegetation of rare earth tailings. Ectopic treatment such as Chinese patent with publication number CN106282554A (application number 201610669586. X) discloses a rare earth mine restoration method, which comprises ball-milling and screening rare earth tailings to obtain tailings raw powder, acidifying, filtering, separating and backfilling to realize mine taillessness, harmlessness, no hidden danger and full green restoration effect. However, the rare earth mine restoration technology only simply utilizes microorganisms and plants, does not consider the soil restoration technology of the waste rare earth tailing sand matrix, and simultaneously solves the problems of water and soil loss, soil property recovery, cd removal and the like, and the research on the related technology for carrying out the treatment of related areas by combining the indigenous fungi with the pioneer plants is few.

Disclosure of Invention

In view of the above, the invention aims to provide a method for restoring soil in an ionic rare earth abandoned mining area, which effectively improves the extremely degraded ecological environment of the ionic rare earth abandoned mining area caused by the abandoned tailings and improves the soil degradation and environmental pollution of the mining area caused by the mountain-destroying mining of rare earth ores.

In order to achieve the above object, the present invention provides the following technical solutions:

the invention provides a method for restoring ionic rare earth abandoned mine soil, which comprises the following steps: mixing the bacterial liquid with tailing sand of the ionic rare earth abandoned mining area, hole-sowing sterilized herbaceous plant seeds or shrub plant seeds, and covering the tailing sand; after 2 weeks, applying nitrogen-phosphorus-potassium fertilizer every 1 week;

the strains in the bacterial liquid comprise trichoderma and/or penicillium oxalicum.

Preferably, the mass ratio of the bacterial liquid to the tailing sand is 1.

Preferably, when the bacteria liquid is trichoderma bacteria liquid, the number of viable bacteria colonies in the bacteria liquid is 6-15/mL;

when the bacterial liquid is the bacterial liquid of penicillium oxalicum, the number of viable bacteria colonies in the bacterial liquid is 6-15/mL;

when the bacteria liquid is a mixed bacteria liquid of trichoderma and penicillium oxalicum, the mass ratio of the bacteria liquid of the trichoderma to the bacteria liquid of the penicillium oxalicum in the bacteria liquid is 1:1-2:1, the number of viable bacteria colonies in the bacteria liquid of the trichoderma is 3-10/mL, and the number of viable bacteria colonies in the bacteria liquid of the penicillium oxalicum is 2-8 lcell/mL.

Preferably, the herbaceous plant seeds comprise paspalum europaeum seeds, ramie seeds, trifolium repens seeds, astragalus sinicus seeds, miscanthus sinensis seeds, alfalfa seeds, pennisetum alopecuroides seeds, festuca arundinacea seeds and/or setaria viridis seeds;

the shrub plant seed comprises Morus Carpesii seed, semen Cassiae Corchorifoliae seed, flos Magnoliae seed, sophora Mollissima seed and/or Broussonetia papyrifera seed.

Preferably, the method for sterilizing seeds of Panicoideae plants comprises: cleaning the seeds of Panicoideae plant with deionized water, and washing with 10 vol% H ₂ O ₂ The washed seeds are surface-sterilized by the aqueous solution for 10min and rinsed by sterile water until the seeds are clean and odorless.

Preferably, before the hole sowing, a planting hole is arranged in the ionic rare earth abandoned mine area, and the diameter of the top surface of the planting hole is 7-10 cm; the plant spacing and the row spacing of the planting holes are all 50-100 cm.

Preferably, 15-80 seeds are planted in each planting hole during hole sowing.

Preferably, after said hole sowing, each planting hole is covered with 200g of sterilized said tailings sand.

Preferably, the nitrogen, phosphorus and potassium fertilizer comprises a Honglad solution diluted by 10 times.

Preferably, the total dosage of the 10-fold diluted Honglad solution is 50-100 mL/planting hole.

The invention provides a method for restoring ionic rare earth abandoned mine area soil, which is characterized by high plant restoration success rate, excellent effect, simple and convenient technical process, easy construction, capability of obviously reducing the Cd content of the soil, water and soil loss rate and the like by utilizing the combination of pioneer plants promoting abandoned rare earth tailings and indigenous fungi, lower cost, attractive appearance, safety, easy popularization and application and huge application prospect and market demand compared with the similar methods. In the embodiment of the invention, the ionic rare earth abandoned mine area in the south rainy region is inoculated with the bacterial liquid of trichoderma and/or penicillium oxalicum, and the broomcorn subfamily plant seeds are sowed in holes, so that Cd in soil can be absorbed obviously, the biomass of plants is improved, the vegetation ecological recovery effect is good, and the method is suitable for rapidly treating Cd pollution of the rare earth tailing abandoned land in the south rainy region.

Drawings

FIG. 1 shows the biomass and enzyme activity changes of ditch millet, wherein QB represents the non-addition group of ditch millet; QB + CS represents the group consisting of paspalum + penicillium oxalicum; QB + MM for paspalum plus Trichoderma group; QB + MIX represents paspalum plus two bacterium groups, the same below;

FIG. 2 shows the change in Cd absorption by paspalum;

FIG. 3 shows the Cd content change before and after soil planting of paspalum;

FIG. 4 shows the biomass change of ramie, where ZM denotes the ramie core; ZM + CS represents the group of ramie plus penicillium oxalicum; ZM + MM represents the Boehmeria nivea group; ZM + MIX represents the two bacterial groups of ramie;

FIG. 5 shows the change of MDA and SOD contents in ramie;

FIG. 6 shows the change of Cd absorption by ramie;

FIG. 7 shows the change of Cd content on the ground and under the ground of ramie;

FIG. 8 shows the Cd content change of soil before and after ramie planting.

Detailed Description

The invention provides a method for restoring ionic rare earth abandoned mine soil, which comprises the following steps: mixing the bacterial liquid with the tailing sand of the ionic rare earth abandoned mining area, hole-sowing the sterilized herbaceous plant seeds or shrub plant seeds, and covering the tailing sand; after 2 weeks, applying nitrogen-phosphorus-potassium fertilizer every 1 week;

The method comprises the following steps of mixing bacterial liquid with the tailing sand of the ionic rare earth abandoned ore area, wherein the mass ratio of the bacterial liquid to the tailing sand is preferably 1. In the invention, when the bacteria liquid is trichoderma bacteria liquid, the number of viable bacteria colonies in the bacteria liquid is preferably 6-15/mL (each colony is 0.8-1.2 mm in diameter); when the bacterial liquid is the bacterial liquid of penicillium oxalicum, the number of viable bacteria colonies in the bacterial liquid is preferably 6-15/mL (each colony is 0.8-1.2 mm in diameter); when the bacteria liquid is a mixed bacteria liquid of trichoderma and penicillium oxalicum, the mass ratio of the bacteria liquid of the trichoderma to the bacteria liquid of the penicillium oxalicum in the bacteria liquid is preferably 1:1-2:1, the number of viable bacteria colonies in the bacteria liquid of the trichoderma is preferably 3-10/mL (each colony is 0.8-1.2 mm in diameter), and the number of viable bacteria colonies in the bacteria liquid of the penicillium oxalicum is preferably 2-8/mL (each colony is 0.8-1.2 mm in diameter). The Trichoderma is preferably Trichoderma (Trichoderma sp.2# D, the preservation number: CCTCC DF 2008172) which is purchased from Islands Standd detection Co., ltd; the Penicillium oxalicum is preferably Penicillium oxalicum (CCTCC WF 2008071) which is purchased from Islands Standd detection, inc. In the embodiment of the invention, the experiment is preferably carried out in the abandoned rare earth tailing area (24-degree 53-degree 33.40-degree N, 115-degree 40-degree 34.76-degree E) of Shanghai village of Jiangxi city of Jiangxi province, the altitude is 302m, and the experiment is carried outA greenhouse with an area of about 256m is built on the site ² 。

The mixing of the invention is preferably to directly sprinkle bacteria liquid on the surface soil, and uniformly mix the bacteria liquid and the tailing sand after sterilization.

The method takes the tailing sand of the ionic rare earth abandoned mine area mixed with the bacterial liquid as a matrix, and holes are sown on the matrix for sterilized herbaceous plant seeds or shrub plant seeds, and the sterilized tailing sand is covered. The herbaceous plant seeds preferably comprise paspalum europaeum seeds, ramie seeds, trifolium repens seeds, milk vetch seeds, miscanthus sinensis seeds, alfalfa seeds, pennisetum alopecuroides seeds, festuca arundinacea seeds and/or green bristlegrass seeds; the shrub plant seeds preferably include Douglas fir seeds, cassia occidentalis seeds, magnolia biondii seeds, sophora japonica seeds, and/or Broussonetia papyrifera seeds. Before the hole sowing, preferably arranging a planting hole in the ionic rare earth abandoned mine area, wherein the diameter of the top surface of the planting hole is preferably 7-10 cm; the plant spacing and the row spacing of the planting holes are preferably 50-100 cm. When the method is used for hole sowing, 15-80 sterilized seeds are preferably planted in each planting hole. The method for sterilizing seeds according to the present invention preferably comprises: cleaning the seeds with deionized water, and washing with 10% H ₂ And (4) disinfecting the surface of the cleaned seeds for 10min by using an O2 aqueous solution, and rinsing the seeds by using sterile water until the seeds are clean and odorless. After the hole sowing, the plant holes are covered with the sterilized tailing sand, and the covering amount of the tailing sand is preferably 200 g/plant hole.

After the hole sowing, the method preferably further comprises field moisture and fertilization management, the specific operation of the field moisture and fertilization management is not particularly limited, and a method well known to a person skilled in the art is adopted, for example, watering can be carried out for 2-6 times, and top dressing can be carried out for 1 time (top dressing according to 1/10 amount of base fertilizer); after the plants grow for 6 months, the plants are harvested, and the plants are dried in the sun and then are measured to obtain relevant indexes, such as the plants can be used as livestock feed according with GB 13078 feed hygienic standard, and the plants can be subjected to centralized incineration harmless treatment after being transferred according with the relevant standards.

After 2 weeks of seedling emergence, nitrogen-phosphorus-potassium fertilizer is applied every 1 week, the nitrogen-phosphorus-potassium fertilizer preferably comprises 10-fold diluted Honglad solution, and the dosage of the nitrogen-phosphorus-potassium fertilizer is preferably 50-100 mL/planting hole.

The method for remediating ionic rare earth abandoned mine soil provided by the invention is described in detail below with reference to examples, but the method is not to be construed as limiting the scope of the invention.

Example 1

A place: waste rare earth tailings mining area (24-53 '33.40 ' N, 115-40 ' E) in Shanxi village of Jiangxi city of Xuanzhou Shangxi county, altitude is 302m, and greenhouse is constructed in experimental site with area of 256m ² . Rare earth soil with low heavy metal cadmium pollution is selected as an experimental area, the content of heavy metal Cd in the experimental site is 0.04mg/kg and is lower than the background value of the soil environment of Ganzhou, namely 0.09mg/kg, and a pot experiment is adopted when exogenous Cd is added under the condition of no pollution to local soil.

Soil properties: the basic physicochemical indexes of the tailings are as follows: 100.0mg/kg of total phosphorus, 170.0mg/kg of total nitrogen, 7.12mg/kg of nitrate nitrogen, 18.4mg/kg of ammonium nitrogen, 2.61g/kg of organic matter, 4.38 of pH value, 608.0mg/kg of lanthanum, 114.0mg/kg of yttrium and 16.8mg/kg of europium. The sterilized tailings sand and soil were placed in a pot for experiment (plastic pot with an upper caliber of 14cm, a lower inner diameter of 7cm, and a pot height of 9 cm).

In the experiment, 4 treatment levels are set, namely, no inoculation treatment, single inoculation of penicillium oxalicum (CCTCC WF 2008071)) and trichoderma (CCTCC DF 2008172) and mixed bacteria of the two (w: w = 1:1) are respectively carried out, 6 parallel treatment levels are set for each treatment, 24 pots are planted in total, and the treatment levels are randomly placed in a greenhouse.

Before planting, the waste rare earth tailing test soil is sterilized, a certain amount of sterilizing agent (hydrogen peroxide, the same as above) is scattered, and CdCl is used ₂ Preparing mother liquor, adding the mother liquor into a flowerpot filled with 600g of soil according to gradients of 0mg/kg, 0.2mg/kg, 0.6mg/kg and 1mg/kg, wherein three concentrations are performed in parallel, planting is performed after balancing for one week, and the Cd content of the soil after balancing is about 4.81 mg/kg. During planting, watering is carried out in the evening of the morning every day, and water is taken from the running water of local mountain feet.

The tailings sand to be tested is put into a basin in 3 layers, sterilized gauze is lined before the tailings sand is put into the basin, 1kg of tailings sand is put into the basin at the bottom layer, 100g of fungi are added in the middle layer for inoculation treatmentThe inoculum per kg tailings sand was dibbled with paspalum europaeum seeds (full seed paspalum europaeum seeds were selected and the ratio was 10% H ₂ O ₂ Disinfecting for 10 minutes, rinsing with deionized water until the mixture is clean and odorless), and covering 200g of tailing sand; an equal amount of sterilized soil was added to the control treatment group. Hoagland nutrient solution with 1/10 concentration is added once every 1 week after seedlings emerge for 2 weeks.

After 6 months, the growth condition of the paspalum is good, the root system has good soil fixing effect, the flowerpot is completely brought back to a laboratory, and the plant height, the plant number and the like of the paspalum, the content of MDA (malondialdehyde), SOD (superoxide dismutase), the content of Cd in heavy metal of plants and the content of Cd in heavy metal of rhizosphere soil are measured. After harvesting, the root system was cleaned and the overground plant length and underground root length of paspalum latifolium were measured with a ruler, and the total fresh weight and the total number of plants were measured.

Determining the mycorrhiza infection rate of the plant root system by adopting a Trimeryl blue staining method; MDA and SOD enzyme activity determination adopts detection kit (purchased from Nanjing to build biology Co., ltd.); the soil physical and chemical index measuring method refers to a soil agricultural chemical analysis method compiled by Lu Rukun (2000); the pH of the soil adopts a potential method; the potassium dichromate oxidation colorimetry is used for measuring organic matters; digesting Total Nitrogen (TN) and Total Phosphorus (TP) of the soil by adopting sulfuric acid-hydrogen peroxide, and analyzing by using a continuous flow analyzer; according to the analysis of soil agricultural chemistry, ammonium Nitrogen (NH 4) ⁺ Determination of-N) NH4 in the soil by extraction with Potassium chloride solution ⁺ Then performing indophenol blue colorimetry to obtain nitrate nitrogen (NO 3) ^－ -N) is determined by a copper cadmium reduction-diazotization coupling colorimetric method by taking an ammonium chloride solution as a substrate; the contents of heavy metal cadmium (Cd) in soil and rare earth elements lanthanum (La), yttrium (Y) and europium (Eu) are determined by a GB/T14506.30-2010 silicate rock chemical analysis method; the mercury (Hg) content was determined by the GB/T22105.1-2008 atomic fluorescence method. And a muffle furnace digestion-hydrochloric acid-AAS method is adopted for measuring the heavy metal of the plants.

1. Biomass and enzyme activity changes

The measurement results of the plant height are shown in FIG. 1, and the average plant height of the paspalum and trichoderma in the four groups is up to 19.50cm after the Cd addition amount of 0.6 mg/kg. The average plant height of the paspalum without adding bacteria is 13.08cm; the average plant height of the paspalum vaginatum and the penicillium oxalicum is 15.50cm; the average plant height of the paspalum and trichoderma is 18.33cm; the average plant height of the paspalum and the two bacterium groups is 11.66cm. The plant height of the paspalum non-adding bacterium group is highest when the Cd addition amount is 0.6mg/kg, the plant height of the paspalum adding penicillium oxalicum group is close to that of the four addition amounts, the plant height of the paspalum adding trichoderma group is increased along with the increase of the Cd addition amount, and the plant height of the paspalum adding two bacterium groups is highest and then shows a descending trend when the Cd addition amount is 0.2 mg/kg. The three groups of bacteria-adding groups have higher average strain length than the bacteria-not-adding groups, the bacteria-adding has the effect of improving the growth of the paspalum, and the combination of the paspalum and the strains is beneficial to the growth of the rare earth mine with high Cd pollution. And the average strain of paspalum and trichoderma in the four groups was the highest, and trichoderma might promote the growth of paspalum. From the mean analysis of the combinations of different Cd dosages and different bacteria (tables 1 and 2), there was no significant difference between the four groups (p > 0.05) at different Cd dosages. From the combination mode of different strains, the plant height of the group consisting of the paspalum and the trichoderma is obviously higher than that of the group consisting of the paspalum and the trichoderma (p is less than 0.01), the plant height of the group consisting of the paspalum and the penicillium oxalicum is obviously higher than that of the group consisting of the paspalum and the two strains (p is less than 0.05), the plant height of the group consisting of the paspalum and the trichoderma is also obviously higher than that of the group consisting of the paspalum and the two strains (p is less than 0.01), and the plant height of the group consisting of the paspalum and the trichoderma has obvious advantages.

The results of the measurement of the number of plants are shown in FIG. 1, and the number of plants of Paspalum vaginatum and Trichoderma reesei in the four groups was 162 plants at the maximum after Cd addition of 1 mg/kg. The average strain number of the paspalum without adding the bacterial group is 52 strains; the average number of the paspalum and penicillium oxalicum groups is 98; the average number of strains of the paspalum and trichoderma is 133; the average number of the strains of the paspalum vaginatum and the two bacterial groups is 85. The number of the paspalum aseptic strains increases along with the increase of the Cd addition amount; the number of the strains of the group consisting of ditch millet and penicillium oxalicum is in a descending trend after the addition of 0Cd, but the number of the strains is higher than that of the strains at the addition of 0Cd under the addition of 1mg/kg of Cd; the number of the paspalum trichoderma strains increases along with the increase of the Cd addition amount; the number of the strains of the two strains of paspalum vaginatum added in the amount of 0-0.6 mg/kg Cd increases, but decreases when the amount of Cd added in the amount of 1mg/kg, but is still higher than the number of strains when the amount of Cd added in the amount of 0 mg/kg. From the mean analysis of the different Cd dosages and the different bacteria combinations (Table 1 and Table 2), there was no significant difference between the four groups (p > 0.05) in the case of different Cd dosages. The combination of different strains showed that the number of the strains in the group consisting of paspalum vaginatum and penicillium oxalicum was significantly higher than that in the group consisting of paspalum vaginatum (p < 0.05), the number of the strains in the group consisting of paspalum vaginatum was significantly higher than that in the group consisting of paspalum vaginatum (p < 0.01), and the number of the strains in the group consisting of paspalum vaginatum and trichoderma was significantly higher than that in the group consisting of ramie and two strains (p < 0.05). The same strain is similar in height, and the number of the paspalum and trichoderma strains has obvious advantages compared with the other three groups.

As a result of measurement of Paspalum MDA (malondialdehyde), as shown in FIG. 1, the highest MDA content of Paspalum was 4.62. Mu. Mol/L in the case of the group of four groups consisting of Paspalum and Penicillium oxalicum at a Cd addition amount of 0.6 mg/kg. The average MDA value of the paspalum non-plus bacteria group is 3.75 mu mol/L; the average MDA value of the group of the paspalum and the penicillium oxalicum is 3.63 mu mol/L; the average MDA value of the paspalum and trichoderma group is 2.66 mu mol/L; the average MDA value of the paspalum plus the two bacterial groups was 2.35. Mu. Mol/L. The MDA value of the paspalum gerbera non-adding bacterium group is approximately in a descending trend along with the adding amount of Cd, and the MDA value added with Cd is lower than the MDA value not added with Cd; the group consisting of ditch millet and penicillium oxalicum reaches the maximum value of MDA of the group when the Cd addition amount is 0.6 mg/kg; the MDA value of the Cd-added group in the ditch millet and trichoderma group is lower than that of the MDA value without Cd; the two strains of paspalum vaginatum are similar to the strain of trichoderma, and the MDA value of the strain with Cd is lower than that of the strain without Cd. Except the group with the penicillium oxalicum, the MDA value of other groups with Cd is lower than that without Cd, according to the fact that Malondialdehyde (MDA) is a product of membrane lipid peroxidation of plant organs in adversity, the degree of damage to plant cell membranes is indicated by the content of the MDA, and the other groups except the group with the penicillium oxalicum are low in stress. From the mean analysis of the different Cd dosages and the different bacteria combinations (Table 1 and Table 2), there was no significant difference between the four groups (p > 0.05) in the case of different Cd dosages. From the group, the MDA value of the paspalum non-added bacteria group was significantly higher than the MDA values of the paspalum added trichoderma group and the paspalum added two bacteria groups (p < 0.05); the paspalum plus penicillium oxalate group was significantly higher than the MDA values of both the paspalum plus trichoderma group and the paspalum plus two bacteria group (p < 0.05).

The SOD (superoxide dismutase) of paspalum was measured as shown in FIG. 1, and the highest SOD content of paspalum was 213.39U/g in the case of 0Cd addition in the non-bacteria-added group of four groups. The average SOD value of the paspalum without adding bacteria is 211.99U/g; the average SOD value of the group of paspalum vaginatum and penicillium oxalicum is 208.03U/g; the average SOD value of the paspalum and trichoderma group is 207.39U/g; the average SOD value of the paspalum and the two bacterium groups is 208.92U/g. The SOD value of the non-bacteria-adding group of the paspalum decreases along with the increase of the adding amount of Cd, the SOD value of the paspalum and penicillium oxalicum reaches the highest value under the adding amount of 0.6mg/kg Cd, the SOD value of the paspalum and trichoderma reaches the lowest value under the adding amount of 0.6mg/kg Cd, and the SOD values of the paspalum and two bacteria groups almost have no obvious change. Superoxide dismutase (SOD) is the first defense line of an antioxidant defense system, and the difference between four groups is not large from the average value, but is higher than that of a ramie group, and the paspalum group is probably better than that of the ramie group in the growth condition in rare earth mines. From the mean analysis of the different Cd dosages and the different bacteria combinations (Table 1 and Table 2), there was no significant difference between the four groups (p > 0.05) in the case of different Cd dosages. There was no significant difference between the four groups for different groups (p > 0.05).

TABLE 1 mean value analysis of biomass and enzyme activity at different Cd addition amounts

TABLE 2 mean value analysis of growth and enzyme activity under different combinations

Note: a, adding no bacterium group of paspalum, namely QB; b, adding pencilomyces oxalicum group from paspalum, namely QB + CS; c, adding a trichoderma group into the paspalum, namely QB + MM; d: two bacterial groups, QB + MIX, were added to ditch millet, the same below.

2. Change in Cd content in plants

The content change of heavy metal Cd before and after soil planting is shown in figure 2, and the total content of Cd absorbed by each group is not large and is about 0.1-1 mg/kg. The percentage of absorbed Cd was the highest at 0Cd addition of the four groups of paspalum vaginatum and two strains, which was 40%. The highest Cd absorption percentage of the paspalum non-mycose plants is 20.59 percent, and the lowest Cd absorption percentage is 2.14 percent; the percentage of Cd absorbed by the paspalum and penicillium oxalicum group plants is 14.15% at most and 2.88% at least; the highest Cd absorption percentage of the paspalum and trichoderma group plants is 12.83%, and the lowest Cd absorption percentage is 2.89%; the percentage of Cd absorbed by the paspalum and the two flora plants was 40.00% at the highest and 2.18% at the lowest. It can be seen that the paspalum group can absorb about 2% of Cd in the soil at the lowest. The Cd absorption content of the paspalum non-bacteria-added plant is in an ascending trend within 0-0.6 mg/kg Cd addition amount, and is reduced when the Cd addition amount is 1 mg/kg. The Cd absorption contents of the plants of the group consisting of paspalum and penicillium oxalicum and the group consisting of paspalum and trichoderma increase with the increase of the Cd addition amount, and the Cd absorption of the plants of the two groups is good under the condition of high Cd. The Cd content absorbed by paspalum vaginatum and two bacteria group plants is in a stable state when the Cd content is 0-0.6 mg/kg, and the high absorptivity is achieved under the condition of high Cd.

The mean analysis of the Cd contents absorbed by the plants is shown in tables 3 and 4, and from different Cd adding amounts, the Cd contents absorbed by the plants at 1mg/kg Cd adding amount are significantly higher than those absorbed by the plants at 0Cd adding amount and 0.2mg/kg Cd adding amount (p < 0.01), which is consistent with the situation shown in FIG. 2, and from different groups, the Cd contents absorbed by the plants have no significant difference (p > 0.05).

TABLE 3 comparison of Cd absorption by ditch millet at different Cd addition amounts

TABLE 4 comparison of Paspalum Cd content in different combinations

3. Change of Cd content in soil

The content change of Cd in soil before and after planting is shown in figure 3, the content of Cd in soil after four groups of plants is increased along with the content of Cd added before planting, and compared with ramie, when the content of Cd is high, namely 1mg/kg of Cd is added, the Cd can be better absorbed by ditch millet soil. The content of Cd absorbed by soil of the paspalum vaginatum group is 77.9 percent at most and 66.99 percent at least; the ratio of Cd content absorbed by soil of the group consisting of ditch millet and penicillium oxalicum is 86.11% at most and 53.81% at least; the content of Cd absorbed by soil of the group consisting of paspalum and trichoderma is 90.17 percent at most and 33.37 percent at least; the ratio of Cd content absorbed by soil of the group of paspalum and two bacterium is 81.17% at most and 25.21% at least.

The mean value analysis of the Cd content after the soil planting is carried out as shown in Table 5 and Table 6, and from the different Cd adding amounts, the Cd content after the soil planting under the Cd adding amount of 0.2mg/kg is obviously higher than the Cd content after the soil planting under the Cd adding amount of 0 (p is less than 0.05); the content of Cd after the soil planting under the adding amount of 0.6 and 1mg/kg of Cd is remarkably higher than that of Cd after the soil planting under the adding amount of 0Cd and 0.2mg/kg of Cd (p is less than 0.01). From different groups, the Cd content is not obviously different after the soil is planted (p is more than 0.05).

TABLE 5 comparison of Cd contents in soil after planting at different Cd addition rates

TABLE 6 pairwise comparison of Cd in planted soil under different combinations

From the above, it can be seen that: (1) growth amount of paspalum combination fungi: the growth amount of the paspalum vaginatum in the trichoderma group is the largest, and the plant length and the plant number are increased along with the improvement of the Cd gradient; the number of strains of the added bacteria group is more than that of the strains without the added bacteria group, and the content of the added bacteria can improve the growth amount of the paspalum.

(2) And the effect of treating Cd by the paspalum vaginatum combined fungi is as follows: the group containing penicillium oxalicum absorbs soil with higher Cd content; from the content of the residual Cd in the soil after planting, the content of the residual Cd in the soil of the group with trichoderma is lower, the Cd absorption capacity of the ditch millet and the two bacterium groups is improved (the highest is 20.16%), and the ditch millet inoculated with the trichoderma has high biological quantity and stronger capacity of removing the Cd in the soil.

Example 2

Before planting, sterilizing the waste rare earth tailings test soil, scattering a certain amount of sterilizing agent (hydrogen peroxide, the same as above), recording the original root length of ramie, and using CdCl ₂ Preparing mother liquor, adding the mother liquor into a flowerpot filled with 2kg of rare earth tailing sand according to gradients of 0, 0.2, 0.6 and 1mg/kg (operation method and embodiment)1 is the same), three concentrations are made in parallel, planting is carried out after one week of balance, and the Cd content in the soil after balance is about 7.72 mg/kg. The ramie seedlings were planted in the same manner as in example 1, and the period from the planting of the ramie seedlings to the growth of the ramie was 6 months, after which the samples were collected and taken to the laboratory for correlation. During planting, watering is carried out in the evening of the morning every day, and water is taken from the running water of local mountain feet. After 6 months, the ramie grows well, the root system has a good soil fixing effect, the flower pots are all brought back to the laboratory, and the plant height, the leaf length, the leaf width, the leaf number, MDA, SOD, the contents of heavy metal Cd in the ground and underground, and the content of heavy metal Cd in the rhizosphere soil are determined according to the same method as the embodiment 1.

1. Plant biomass and enzyme activity

The results of the determination of the plant height growth are shown in FIG. 4, the average plant height of the ramie and penicillium oxalicum group is the highest under the condition of adding Cd of 0.2mg/kg and reaches 16.67cm, the plant heights of the ramie non-bacteria combination and the oxalic acid group under the condition of adding Cd of 0.2mg/kg have obvious advantages compared with the adding Cd of other Cd, and the Cd under 0.2mg/kg is presumed to have a certain promotion effect on the growth of the ramie. The strain height of the ramie is not greatly influenced by adding the strain under the original soil, but with the increase of the concentration of Cd, the strain height of the ramie is promoted to a certain extent by adding the strain combination compared with not adding the strain, and the combination of the ramie and the strain is favorable for the growth of rare earth mines with high Cd pollution. From the mean value analysis (tables 7 and 8), the adding amount of 0.2mg/kg Cd has obvious effect of promoting the plant height of ramie (p < 0.05) compared with 0Cd, the adding amount of the other Cd has no obvious influence on the plant height of the ramie (p > 0.05), and the combination mode has no obvious influence on the plant height (p > 0.05).

The results of the leaf length measurements are shown in FIG. 4, where the average leaf length of the Ramie + Penicillium oxalicum group at a Cd addition of 0.2mg/kg was longest and reached to 4.83cm. Under the condition of not adding Cd, the length of each group of leaves has no obvious change; in the ramie oxalic acid addition composition, the addition of Cd of 0.2mg/kg has obvious promotion effect on ramie blades, and the length of the ramie blades is reduced along with the increase of the addition; under the condition that trichoderma and both fungi are added, the length of the leaves tends to increase along with the increase of the addition amount of Cd, and the addition of the trichoderma can promote the growth of the leaves to a certain extent. Under the original rare earth soil, the ramie leaf length tends to increase along with the increase of the concentration of Cd, and the growth of ramie leaves can be promoted by the combined action of the addition of Cd and rare earth elements. From the analysis of the mean value (tables 7 and 8), the Cd addition has no obvious influence on the length of ramie leaves (p > 0.05), and the combination mode has no obvious influence on the plant height (p > 0.05).

The results of the leaf width measurement are shown in FIG. 4, where the average leaf width of the Ramie + Penicillium oxalicum group at Cd addition of 0.2mg/kg was the largest and reached 3.50cm. Under the condition of not adding Cd, the width of each group of leaves has no obvious change; in the ramie oxalic acid addition combination, the ramie leaf width is obviously increased at the Cd addition of 0.2mg/kg, and the leaf width is reduced along with the increase of the Cd addition. Under the original rare earth soil, the ramie leaf width tends to increase along with the increase of the concentration of Cd, and the growth of the ramie leaf width can be promoted by the combined action of the Cd and the rare earth elements. From the mean value analysis (tables 7 and 8), the Cd addition had no significant effect on the ramie leaf width (p > 0.05) and the combination had no significant effect on the leaf width (p > 0.05).

The measurement result of the number of leaves is shown in figure 4, under the original rare earth tailing soil, the number of ramie leaves is the most, 14 ramie leaves exist, and the leaves grow vigorously; the leaf number is obviously reduced along with the increase of the concentration of Cd; the ramie trichoderma group has 13 leaves at the addition of 0.2mg/kg Cd, and the growth is luxuriant, and the trichoderma can promote the growth of the leaves from the other two groups of bacteria. From the mean value analysis (tables 7 and 8), the Cd addition had no significant effect on the ramie leaf width (p > 0.05) and the combination had no significant effect on the leaf width (p > 0.05).

TABLE 7 mean growth analysis at different Cd loadings

Note: bold font indicates significant correlation, p <0.05, p <0.01, the same applies below.

TABLE 8 mean growth analysis in different combinations

Note: a, adding no bacterium group into ramie, namely ZM; b, ramie adds penicillium oxalicum group, namely ZM + CS; c, ramie adds the trichoderma group, namely ZM + MM; d: two bacterial groups, ZM + MIX, were added to Ramie.

The MDA (malondialdehyde) determination result of ramie is shown in FIG. 5, the MDA content of the ramie + penicillium oxalicum group is maximum under the condition of 0.2mg/kg Cd addition amount and reaches 16.25 mu mol/g; the ramie and trichoderma group had the smallest MDA content of 3.65 mu mol/g at a Cd addition of 0.2 mg/kg. The average MDA value of the ramie non-bacterium-added group is 6.92 mu mol/g; the average MDA value of the ramie plus penicillium oxalicum is 10.75 mu mol/g; the average MDA value of the ramie plus trichoderma fungus is 5.99 mu mol/g; the average MDA value of ramie plus two bacteria is 7.80 mu mol/g. Besides the trichoderma fungus group, the MDA value of the penicillium oxalicum group is higher than that of a control group without the added bacteria, and the possibility of damaging the cells of the trichoderma fungus group plants is lower. The change trend of the MDA content of the whole group along with the addition of the Cd content is not obvious, which indicates that the stress action of Cd on ramie is not obvious, and only the oxalic acid group generates more MDA content under the condition of adding 0.2mg/kg Cd gradient, and then the MDA content is reduced to the similar level of the control group.

The determination result of the ramie SOD (superoxide dismutase) is shown in figure 5, the SOD content of the ramie non-bacterium-added group is 210.50U/g under the condition of 0.2mg/kg Cd addition; the SOD content of the ramie and trichoderma combination is the lowest under the condition that the adding amount of Cd is 0.2mg/kg, and is 52.06U/g. The average SOD value of the ramie strain-free group is 173.86U/g; the average SOD value of the ramie strain-free group is 144.99U/g; the average SOD value of the ramie strain-free group is 114.98U/g; the average SOD value of the ramie strain-free group is 143.25U/g, and the SOD value of each group is lower than that of a bacterium-free control group. Superoxide dismutase (SOD) is the first defense line of an antioxidant defense system, and except ramie, the bacterium groups are not added, and the other groups are reduced to different degrees, which shows that the production of the SOD can be reduced by adding fungi.

2. Cd content of ramie

As can be seen from the comparison of the Cd content of the four groups of ramie with the Cd content of the soil before planting (FIG. 6), the addition of 0.6mg/kg Cd in the ramie non-bacteria-added group and the ramie-Trichoderma-added group has an obvious Cd absorption content, while the addition of 0.6mg/kg Cd in the ramie-penicillium oxalicum group and the addition of two strains in the ramie group have an obvious Cd absorption content below the addition of 0.6mg/kg Cd, while the Cd absorption content of the ramie is extremely low under the condition of 1mg/kg Cd. The lowest value of Cd content in soil of ramie non-bacterium-added group absorption Cd is 42.86%, and the highest value is 72.54%; the minimum value of Cd absorbed by the ramie penicillium oxalicum group in the Cd content in the soil is 7.64%, and the maximum value is 62.50%; the minimum content of Cd in the soil is 47.08 percent by the ramie trichoderma combined group, and the maximum content of Cd in the soil is 82.68 percent; the minimum content of Cd in the soil is 9.46 percent and the maximum content is 56.90 percent in the ramie absorbed by two bacterium groups. As can be seen, the ramie and Trichoderma group has a strong ability to absorb Cd in four groups.

As can be seen from the results (FIG. 7) of the ratio of Cd content in the four groups of overground and underground parts, the value of the plant transport coefficient of the ramie non-bacterium-added combination is in a descending trend along with the increase of the Cd adding amount, and more Cd are enriched in the underground root parts; the ramie added with the trichoderma group has the transport coefficient value which is in the rising trend when the adding amount of Cd is less than 0.6mg/kg, and the transport coefficient is extremely low to about 7 percent when the adding amount of Cd is 1mg/kg, and the transport capacity of the ramie added with the trichoderma group is limited by high cadmium content; the ramie added with the penicillium oxalicum group has the transport coefficient not exceeding 80% under the adding amount of 1mg/kg Cd, but can reach more than 2% under the adding amount of 1mg/kg Cd, and the penicillium oxalicum group promotes the transport capacity of plants under high cadmium; the two bacterial groups added have high transport capacity similar to the penicillium oxalicum group at the Cd addition of 1 mg/kg. The four groups of comparison show that both trichoderma and penicillium oxalicum can improve the Cd transferring capability of the ramie under the condition of adding 0-0.6 mg/kg of Cd, and the penicillium oxalicum can obviously improve the Cd transferring capability of the ramie under the condition of adding 1mg/kg of Cd.

And (4) comparing the Cd contents of the overground part and the underground part with each other by a non-parametric analysis method when the Cd contents of the overground part and the underground part do not accord with normal distribution. From the difference of Cd contents of the overground part and the underground part of different groups (Table 9), the Cd content of the overground part of the ramie plus penicillium oxalicum combination is remarkably higher than that of the ramie plus no bacterium combination (p is less than 0.01); the Cd content of the overground part of the ramie and trichoderma combination is remarkably higher than that of the ramie and no bacterium combination (p is less than 0.01); the Cd content of the overground part of the ramie with the two bacteria is obviously higher than that of the ramie without the bacteria (p is less than 0.01); while the Cd content of the underground part is not obviously different in the combination (p > 0.05). From the different Cd gradient adding amounts in the early stage (Table 10), the content of Cd in the overground part is obviously different only when the adding amount of Cd is 0.6mg/kg and the adding amount of Cd is 0 (p is less than 0.05), and the rest is not obviously different (p is more than 0.05); the Cd content of the underground part is only obviously different between 1mg/kg Cd addition and 0Cd addition (p < 0.05), and the rest is not obviously different (p > 0.05). As can be seen from the group difference, the inoculation of the strain can obviously improve the absorption amount of Cd on the overground part of the ramie. As can be seen from the difference of the early Cd addition gradients, the addition amounts of 1mg/kg Cd and 0.6mg/kg Cd are significantly higher than that of the group without Cd in the control group, which is basically consistent with that in FIG. 7.

TABLE 9 comparison of Cd contents in ground and underground with different combinations

TABLE 10 comparison of Cd contents in underground and overground regions at different Cd addition amounts

3. Change of Cd content in soil

The results of the content change of heavy metal Cd before and after soil planting can be known (figure 8), the cadmium content after four groups of planting is obviously reduced after the addition of Cd is balanced for one week, the soil Cd content after ramie non-bacterium group planting is increased along with the increase of the concentration of the initially added Cd, the addition amount of 0-0.6 mg/kg Cd in the other three groups is in an increasing trend, the addition amount of 1mg/kg Cd is obviously reduced, the content of Cd absorbed by ramie is known, and the addition amount of 1mg/kg Cd can cause a large amount of Cd loss in the penicillium oxalicum group. The highest Cd absorption ratio of ramie non-bacterium-added group soil is 46.43%, and the lowest Cd absorption ratio is 19.29%; the highest Cd absorption ratio of the ramie penicillium oxalicum group soil is 60.00 percent, and the lowest Cd absorption ratio is 1.91 percent; the highest Cd absorption ratio of ramie and trichoderma group soil is 54.17%, and the lowest Cd absorption ratio is 11.84%; the maximum ratio of Cd absorbed by the ramie and two bacterium groups is 51.85, and the minimum ratio is 3.24%. Comparing every two of the strains according to a non-reference test (Table 11), wherein the soil Cd content of the ramie non-bacteria group is obviously higher than that of the ramie penicillium oxalicum group and the ramie bacteria group (p is less than 0.05); as can be seen from the fact that different amounts of Cd are added, the content of Cd in the soil after the Cd adding group of 0.6mg/kg is planted is remarkably higher than that of the Cd group not added (p is less than 0.01), and the content of Cd in the soil after the Cd adding group of 0.6mg/kg is planted is remarkably higher than that of the Cd adding group of 1mg/kg (p is less than 0.05).

TABLE 11 comparison of Cd contents in soil at different Cd dosages and different groups

From the above, it can be seen that (1) ramie combines the growth of two fungi: the ramie penicillium oxalicum group grows best. The adding amount of 0.2mg/kg of exogenous Cd has certain promotion effect on the plant height and the number of leaves of the ramie, and the plant height, the leaf length and the leaf width of the group added with the penicillium oxalicum have obvious advantages compared with other groups under the condition of 0.2mg/kg of Cd. Compared with the control group of Cd at 0mg/kg, the plant height, the leaf length and the leaf width of each group of plants are increased.

(2) The ramie combines two fungi to treat Cd: the average Cd-absorbing capacity of the ramie-trichoderma strain group was the strongest among the four groups (78.11%). From the aspect of ramie growth, the ramie plus penicillium oxalicum group has better growth potential; from the aspect of the aboveground/underground Cd ratio, namely the ramie enrichment coefficient, when the penicillium oxalicum is inoculated in the ramie, the enrichment coefficient is higher; both the trichoderma group and the penicillium oxalicum group can improve the Cd transferring capacity of the ramie, and the ramie and trichoderma group has higher Cd absorbing content and stronger transferring capacity; from the view of the content of the residual Cd in the soil after planting, the content of the residual Cd in the soil after planting without adding the bacterium group is higher than that of the inoculating bacterium group, the inoculating bacterium group is beneficial to reducing the content of the Cd in the soil, and the content of the residual Cd in the soil of the ramie penicillium oxalicum group is lower.

The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and amendments can be made without departing from the principle of the present invention, and these modifications and amendments should also be considered as the protection scope of the present invention.

Claims

1. The method for restoring the ionic rare earth abandoned mine area soil is characterized by comprising the following steps of: mixing the bacterial liquid with tailing sand of the ionic rare earth abandoned mining area, hole-sowing sterilized herbaceous plant seeds or shrub plant seeds, and covering the tailing sand; after 2 weeks, applying nitrogen-phosphorus-potassium fertilizer every 1 week;

the strains in the bacterial liquid comprise trichoderma and/or penicillium oxalicum; the trichoderma is trichoderma (II)Trichoderma sp2#D, accession number: CCTCC DF 2008172; the penicillium oxalicum is penicillium oxalicum (B)Penicillium oxalicum) The preservation number is: CCTCC WF 2008071;

the mass ratio of the bacterial liquid to the tailing sand is 1;

the herbaceous plant seeds comprise paspalum europaeum seeds, ramie seeds, trifolium repens seeds, astragalus sinicus seeds, miscanthus sinensis seeds, alfalfa seeds, pennisetum alopecuroides seeds, festuca arundinacea seeds and/or green bristlegrass seeds;

the shrub plant seeds comprise Douglas fir seeds, semen Cassiae Nomamis, flos Magnoliae, sophora japonica seeds and/or Broussonetia papyrifera seeds;

when the bacteria liquid is trichoderma bacteria liquid, the number of viable bacteria colonies in the bacteria liquid is 6 to 15/mL;

when the bacterial liquid is the bacterial liquid of the penicillium oxalicum, the number of viable bacteria colonies in the bacterial liquid is 6-15/mL;

when the bacteria liquid is a mixed bacteria liquid of trichoderma and penicillium oxalicum, the mass ratio of the bacteria liquid of the trichoderma to the bacteria liquid of the penicillium oxalicum in the bacteria liquid is 1 to 2, the number of viable bacteria colonies in the bacteria liquid of the trichoderma is 3 to 10/mL, and the number of viable bacteria colonies in the bacteria liquid of the penicillium oxalicum is 2~8/mL;

before hole sowing, arranging a planting hole in the ionic rare earth abandoned ore area, wherein the diameter of the top surface of the planting hole is 7-10cm; the planting distance of the planting holes is 50 to 100 cm;

when the hole sowing is carried out, 15-80 seeds are planted in each planting hole;

after the hole sowing, covering 200g of the sterilized tailing sand on each planting hole;

the nitrogen, phosphorus and potassium fertilizer comprises 10 times diluted Honglad solution, and the total dosage of the 10 times diluted Honglad solution is 50-100 mL/planting hole;

the soil remediation comprises adsorption of Cd in the soil.