Method for reducing content of toxic elements Cr, Hg and As in alpine meadow soil

Abstract

The invention provides a method for reducing the content of toxic elements Cr, Hg and As in alpine meadow soil, and belongs to the technical field of soil heavy metal remediation. According to the method, management measures of enclosing, winter grazing and artificial unicast oats are implemented in alpine meadows of the Qinghai-Tibet Plateau, so that a surface community structure and the distribution condition of three potential soil toxic elements, namely underground heavy metals Cr, Hg and As, are adjusted, and a microbial community structure in the soil is influenced; the alpine meadow carbon metabolism regulation and control agent can effectively regulate and control the alpine meadow carbon metabolism process, effectively improves the content of organic carbon in the alpine meadow soil, and opens up an efficient path for the restoration, maintenance and sustainable evolution of an alpine meadow ecological system, and the alpine meadow carbon metabolism regulation and control agent can effectively regulate and control the alpine meadow carbon metabolism process and the alpine meadow soil.

Description

Technical Field

[0001] The invention belongs to the technical field of soil heavy metal remediation, and specifically relates to a method for reducing the contents of toxic elements Cr, Hg and As in alpine meadow soil. Background Art

[0002] Grassland is one of the most important ecosystems on Earth. It not only provides abundant biological resources for human beings, but also plays a key role in maintaining the carbon balance of the Earth. However, with the continuous growth of the global population and the rapid development of the economy, non-degradable pollutants such as Cr, Hg, As, Cd, and Pb, which are soil potentially toxic elements (PTEs), are gradually infiltrating grassland ecosystems through natural processes (such as the formation of alluvial deposits) and human activities (such as agricultural runoff and mining operations). These soil potentially toxic elements can be present in the soil in the form of free cations (such as Cu 2+ 、Cd 2+ 、Zn 2+ ) with inorganic or organic ligands (such as ZnCl + , CdCl3, metal citrates) or in combination with colloidal substances. The infiltration of potentially toxic elements in the soil causes the soil quality to decline, which has a negative impact on the productivity of grasslands. They weaken the cation exchange capacity of the soil, reduce the effectiveness of nutrients and organic matter, and inhibit the basic respiration of the soil. In addition, potentially toxic elements in the soil will interfere with the photosynthesis mechanism inside the plant, affecting the light harvesting complex II (LHC II), the electron transfer process and the function of photosynthetic pigments, further endangering the health of the plant and the stability of the ecosystem.

[0003] Studies have found that potentially toxic elements in the soil play an important role in the biogeochemical process of soil organic carbon (SOC). As these potentially toxic elements gradually accumulate in the soil, the chemical structure stability of soil organic carbon is significantly weakened, its normal biogeochemical cycle is disrupted, and the balance of the soil microbial ecosystem is also impacted. The alpine meadows on the Qinghai-Tibet Plateau are sensitive to global climate change, and even slight climate changes can trigger chain reactions. In alpine meadow areas, how to effectively control and reduce the content of potentially toxic elements in the soil has become an urgent problem to be solved. Summary of the invention

[0004] In view of this, the object of the present invention is to provide a method for reducing the content of toxic elements Cr, Hg and As in alpine meadow soil, which can regulate the abundance of dominant bacteria in the soil and increase the organic carbon content of alpine meadow soil.

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

[0006] The invention provides a method for reducing the contents of toxic elements Cr, Hg and As in the soil of an alpine meadow. The method comprises performing enclosure management, winter grazing or artificial sowing of oats in the alpine meadow.

[0007] Preferably, the alpine meadow includes the alpine grass Kobresia dwarf meadow at an altitude of more than 3,200 meters on the Qinghai-Tibet Plateau.

[0008] As an implementation method, the enclosure management is to fence off the alpine meadow, prohibit grazing throughout the year, and the enclosure period is 12 years.

[0009] As an implementation mode, the winter grazing method includes adopting baby's breath style grazing from October of each year to May of the following year.

[0010] As an embodiment, the method for artificially sowing oats comprises planting oats on grassland, applying organic fertilizers and removing stubbles during the planting process.

[0011] The present invention also provides the application of the above method in regulating the abundance of dominant bacterial flora and / or increasing the organic carbon content in alpine meadow soil.

[0012] Preferably, the dominant bacterial community in the soil includes prokaryotes or fungi. The prokaryotes include Proteobacteria, Verrucomicrobia, and Chloroflexi; the fungi include Basidiomycota and Chytridiomycota.

[0013] Preferably, in the prokaryotic phylum level, Proteobacteria has an enrichment effect on Cr, Verrucomicrobia has a decomposition effect on Cr, and Chloroflexi has a decomposition effect on Hg. In the fungal phylum level, Basidiomycota has a significant decomposition effect on Cr, and Chytridiomycota has a significant decomposition effect on Hg.

[0014] Preferably, the dominant prokaryotic flora in the soil comprises g_unclassified_c_Betaproteobacteria, g_Bradyrhizobium, g_unclassified_p_Candidatus_Rokubacteria, and g_unclassified_p_Chloroflexi. The dominant fungal flora in the soil comprises g_Diversispora, g_Glomus, g_Penicillium, g_Aspergillus, and g_Gigaspora.

[0015] Preferably, in the prokaryotic genus level, g_unclassified_c_Betaproteobacteria has an enrichment effect on Cr, g_Bradyrhizobium has a significant decomposition effect on Cr, g_unclassified_p_Candid atus_Rokubacteria has an enrichment effect on Hg, and g_unclassified_p_Chloroflexi has a significant decomposition effect on Hg. In the fungal genus level, g_Diversispora has a significant decomposition effect on Hg, g_Glomus has a significant decomposition effect on Cd, and g_Penicillium, g_Aspergillus and g_Gigaspora all have significant decomposition and enrichment effects on As.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] The present invention provides a method for reducing the contents of toxic elements Cr, Hg and As in alpine meadow soil. By implementing management measures such as enclosure, winter grazing and artificial monoculture of oats in the alpine meadow, the distribution of three potentially toxic elements of underground heavy metals Cr, Hg and As in the soil can be effectively improved, their contents can be reduced, and the microbial community structure in the soil can be affected, thereby stimulating the enrichment and decomposition capabilities of dominant microbial communities for heavy metals, thereby effectively regulating the carbon metabolism process of the alpine meadow, and effectively increasing the content of organic carbon in the alpine meadow soil, thereby providing extremely valuable technical support and guarantee for the stability, health and sustainable development of the alpine meadow ecosystem. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 Different grassland management methods in the experimental area: (a): fencing; (b): winter grazing; (c): artificial monoculture of oats.

[0019] Figure 2 Sampling method for the trial area.

[0020] Figure 3 Composition and diversity of soil microbial communities under different grassland management measures, (a): abundance of prokaryotic communities at the phylum level; (b): abundance of prokaryotic communities at the genus level; (c): abundance of fungal communities at the phylum level; (d): abundance of fungal communities at the genus level.

[0021] Figure 4 Effects of potentially toxic elements in soil on microbial communities and soil physicochemical properties, (a) and (b): Pearson correlation between bacterial genus and soil heavy metals; (c) and (d): Pearson correlation between fungal genus and soil heavy metals, *: p < 0.05, **: p < 0.01. DETAILED DESCRIPTION

[0022] The invention provides a method for reducing the contents of toxic elements Cr, Hg and As in the soil of an alpine meadow. The method comprises performing enclosure management, winter grazing or artificial sowing of oats in the alpine meadow.

[0023] In the present invention, the alpine meadow includes the alpine grass Kobresia humilis meadow at an altitude of more than 3,200 meters on the Qinghai-Tibet Plateau. As an embodiment, the alpine meadow can be selected from the slope at the southern foot of the eastern section of Lenglongling, the northern branch of Qilian Mountain in the northeast corner of the Qinghai-Tibet Plateau. The temperature difference between day and night in this region is large, the four seasons are not obvious, the summer is short, cool and has more precipitation, and the winter is cold and dry, which belongs to the typical plateau continental climate. The vegetation type is the alpine grass Kobresia humilis meadow, and the dominant species are Kobresia humilis, Elymus nutans, Stipa aliena, Gentianastraminea and Oxytropis kansuensis.

[0024] In the present invention, enclosure management, winter grazing or artificial sowing of oats are adopted in alpine meadows. The enclosure management is to fence and cultivate the alpine meadows, and grazing is prohibited throughout the year. It has been fenced since 2006, and the enclosure period is 12 years during the trial period of 2018. That is, within a certain period of time, the meadow is protected by facilities such as fences and is not used, so that the grass grows naturally. The winter grazing method includes grazing in a star-shaped manner from October to May of the following year. The grazing rate of the area reaches more than 95%, and the grassland is not degraded. The grass is completely eaten by cattle and sheep, leaving only some debris, and there is almost no standing dead matter on the ground. The grazing time is from 9 am to 7 pm every day, and grazing is prohibited after each grazing cycle. The artificial sowing of oats method includes planting oats, an annual grass plant, in the grassland, and applying organic fertilizers and removing stubble normally during the planting process.

[0025] The present invention provides a method for reducing the content of toxic elements Cr, Hg, and As in alpine meadow soil, which is used to adjust the abundance of dominant bacterial communities and / or increase the organic carbon content in alpine meadow soil. Preferably, the dominant bacterial community in the soil includes prokaryotes or fungi. Further preferably, the prokaryotic phylum level includes Proteobacteria, Verrucomicrobia, and Chloroflexi. The fungal phylum level includes Basidiomycota and Chytridiomycota. Among them, Proteobacteria in the prokaryotic phylum level has a significant enrichment effect on Cr, Verrucomicrobia has a significant decomposition effect on Cr, and Chloroflexi has a decomposition effect on Hg. In the fungal phylum level, Basidiomycota has a significant decomposition effect on Cr, and Chytridiomycota has a significant decomposition effect on Hg.

[0026] Further preferably, the dominant bacterial community prokaryotic genus level in the soil includes g_unclassified_c_Betaproteobacteria, g_Bradyrhizobium, g_unclassified_p_Candidatus_Rokubacteria, and g_unclassified_p_Chloroflexi. The dominant bacterial community fungal genus level in the soil includes g_Diversispora, g_Glomus, g_Penicillium, g_Aspergillus, and g_Gigaspora. Among them, in the prokaryotic genus level, g_unclassified_c_Betaproteobacteria has an enrichment effect on Cr, g_Bradyrhizobium has a significant decomposition effect on Cr, g_unclassified_p_Candidatus_Rokubacteria has an enrichment effect on Hg, and g_unclassified_p_Chloroflexi has a significant decomposition effect on Hg. At the fungal genus level, g_Diversispora had a significant decomposition effect on Hg, g_Glomus had a significant decomposition effect on Cd, and g_Penicillium, g_Aspergillus and g_Gigaspora all had significant decomposition and enrichment effects on As.

[0027] In the present invention, there is no special limitation on the detection methods of soil pH, soil bulk density, soil water content, soil organic carbon, soil potential toxic element content, etc., and conventional methods in the art can be used. For example, the soil water content can be determined by the drying and weighing method in accordance with the national standard GB / T 19422.1-2004; the soil pH can be determined by the national standard LY / Y 1239-1999; the organic carbon (SOC) in the soil can be determined by the potassium dichromate oxidation-external heating method in the national standard GB 7857-1987; and the content of potential toxic elements in the soil can be detected by atomic absorption spectroscopy, atomic fluorescence spectroscopy, electrochemical method, etc.

[0028] In the following embodiments, unless otherwise specified, all of them are conventional methods.

[0029] Unless otherwise specified, the materials and reagents used in the following examples can be obtained from commercial sources.

[0030] The technical solution provided by the present invention is described in detail below in conjunction with the accompanying drawings and embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0031] Example 1

[0032] Site selection and division of experimental area: The experiment was conducted at the National Field Scientific Observation and Research Station of Alpine Grassland Ecosystem in Haibei, Qinghai. The Haibei Station is located on the southern slope of the eastern section of Lenglongling, the northern branch of Qilian Mountain, in the northeast corner of the Qinghai-Tibet Plateau, with an average altitude of 3200m. The temperature difference between day and night in this area is large, and the four seasons are not obvious. The summer is short, cool and has more precipitation, and the winter is cold and dry. It is a typical plateau continental climate. The average temperature is -3.31℃, the average daily maximum temperature is 11.87℃, and the minimum temperature is -19.73℃. The vegetation type is alpine grass dwarf Kobresia meadow. The experiment designed three different grassland management types, with one plot of land being enclosed management (FE), enclosed all year round, and the sample plots within the fence were systematically prohibited from grazing, and livestock were prohibited from entering to eat and trample all year round. Another piece of land is set up for winter grazing management (WG). This grassland is located outside the enclosure area. In this area, winter grazing is carried out from October to May of the following year. The grass is completely eaten by cattle and sheep, leaving only some debris. There is almost no standing dead matter on the ground. The grazing time is from 9:00 to 19:00 every day. After each grazing cycle, it is prohibited to graze. Another piece of land with the same area is set up for artificial single-sowing oats (Avena sativa L.) management (AU). Oats are artificially planted, and the planting process includes the application of organic fertilizers and the removal of stubble, such as Figure 1 shown.

[0033] Sampling treatment: Three 50cm×50cm sub-plots were randomly selected in each different grassland type for vegetation survey, mainly to investigate the height and coverage of vegetation, and calculate the richness of vegetation community. Soil samples were collected from each surveyed and mowed sub-plot. In the selected 9 sub-plots, a 3.5cm diameter soil auger was used to sample at three points along the diagonal line in the 50×50cm sample box to minimize the heterogeneity of sampling, and microorganisms were sampled in the 0-10cm soil layer, such as Figure 2 As shown. To ensure uniformity, three soil microbial samples collected in each replicate were mixed into one sample. Before mixing, roots, stones and other debris were carefully removed from the soil microbial samples. The processed soil samples were divided into two groups using the quartering method, one of which was used to assess the soil water content (SWC). The other group was placed in a cool, dry and well-ventilated place to dry for later use. After the soil was dry, it was divided into three equal parts. One dry soil sample was ground and sieved through a 2mm sieve to determine the pH value of the soil; one dry soil sample was ground and sieved through a 0.15mm sieve to determine the content of soil organic matter and soil physical and chemical properties analysis; the last part was stored in a -4°C environment for sample retention. In addition, a 100cm 3 Additional soil samples were collected by the ring cutter in layers and brought back to the laboratory for determination of soil bulk density (SBD). Aboveground biomass (AGB) and belowground biomass (BGB) were determined by collecting surface plants and underground roots from the sample plots, and soil physical and chemical properties were determined, including pH, soil bulk density, soil water content, soil organic carbon, and various nutrients and the content of potentially toxic elements in the soil.

[0034] Soil bulk density (SBD) = oven-dry soil weight / ring volume;

[0035] Soil water content (SWC) = soil weight difference before and after drying / soil fresh weight × 100%

[0036] All statistical analyses were performed using R4.3.2, and the test items were log transformed to ensure data normality and variance homogeneity. One-way analysis of variance (ANOVA) and Duncan multiple comparisons were used to reveal the differences in vegetation diversity and soil physicochemical parameters between different grassland management types.

[0037] The results are shown in Tables 1 and 2. The aboveground biomass and underground biomass of enclosure management were lower than those of winter grazing management. The underground biomass of artificial monoculture oats was significantly lower than that of winter grazing management and enclosure management. However, the aboveground biomass was significantly increased by artificial monoculture oats. Bulk density is an important indicator of soil compactness and is closely related to soil porosity, permeability and water conservation function. Low soil bulk density means that the soil is loose and has more pores, while high soil bulk density means that the soil is compact and has low porosity. Enclosure management and winter grazing management significantly increased soil water content and reduced soil bulk density, which had a significant impact on the increase of soil organic carbon. Vegetation Richness and carbon storage were the highest in winter grazing management, indicating that winter grazing management is conducive to maintaining vegetation diversity and carbon sequestration, and winter grazing significantly increased soil carbon storage. Grassland management measures have a significant effect on the contents of three potentially toxic elements in soil: Cr, Hg and As. Compared with the situation before the implementation of different management measures in 2006, the three management measures of fencing management, winter grazing management and artificial monoculture of oats can reduce the contents of these three potentially toxic elements in the soil, indicating that these management measures can effectively reduce the contents of potentially toxic elements in the soil.

[0038] Table 1 Contents of potentially toxic elements in vegetation under different management measures in alpine meadows

[0039]

[0040] Values ​​are mean ± standard error of the mean (n = 3). Lowercase letters * indicate significant differences (P < 0.05) compared with the control group (measured in 2006) according to Duncan's post hoc test.

[0041] Table 2 Vegetation diversity and basic physical and chemical properties of soil under different management measures in alpine meadows

[0042]

[0043]

[0044] Values ​​are mean ± standard error of the mean (n = 3). Different lowercase letters a, b indicate significant differences (P < 0.05) according to Duncan's post hoc test.

[0045] Example 2

[0046] Using Qubit TMTotal genomic DNA was extracted using a dsDNA soil DNA extraction kit (Life Technologies, CA, USA). The OD value was between 1.8 and 2.0, and the DNA content was above 1 μg for library construction. The total DNA content of each sample was 1 μg, which was used as the input material for DNA sample preparation. Ultra TM DNA LibraryPrep Kit for Illumina (NEB, USA) was used to generate sequencing libraries according to the manufacturer's recommendations, and index codes were added to the attribute sequences of each sample. DNA samples were ultrasonically fragmented into 350 bp in size, followed by end polishing, a-tailing, and ligation with full-length adapters for Illumina sequencing and further PCR amplification. Finally, the products were purified using the AMPure XP system, and the size distribution of the libraries was analyzed using an Agilent 2100 bioanalyzer and quantified using real-time fluorescence quantitative PCR. Index-encoded samples were clustered on the cBot cluster generation system according to the manufacturer's instructions. After cluster generation, library preparation was sequenced on the Illumina HiSeq platform to generate paired-end reads.

[0047] Nine soil DNA samples were analyzed by Metagenome assembly. Raw sequencing data were obtained by Readfq (V8, https: / / github.com / cjfields / readfq) and Bowtie2 software (version 2.2.4, http: / / bowtie-bio.sourceforge.net / bowtie2 / index.shtml) for quality control and assembly. Hybrid assembly was performed using SOAPdenovo (V2.04) / MEGAHIT (v1.0.4-beta), and redundancy was removed using CD-HIT software (V4.5.8, http: / / www.bioinformatics.org / cd-hit / ) to construct a non-redundant gene catalog. The Unigenes were aligned with the bacterial, fungal, and archaeal sequences extracted from the NCBI NR database (Version 2018-01-02, https: / / www.ncbi.nlm.nih.govl) using the DIAMOND software (v0.9.9.110, https: / / github.com / bbuchfink / diamond / ), and species annotations were obtained from the corresponding taxonomic information databases.

[0048] All statistical analyses were performed using R 4.3.2. First, the microbial community data and KEGG KO metabolic pathway gene abundance data were subjected to the “hellinger” transformation to ensure data normalization and variance homogeneity. The microbial community structure was analyzed using the “statnet” package in R 4.3.2 software, and the “circli ze” package was used for visualization. The correlation between heavy metals and microbial communities and soil physicochemical properties was estimated using the “Hmisc” and “vegan” packages, and the correlation network structure analysis was performed using the igraph package, and finally visualized using the ggplot2 package.

[0049] The results are as follows Figure 3 and Figure 4 As shown in the results, it was found that at the phylum level, the soil prokaryotic community was dominated by Proteobacteria, Acidobacteria and Actinobacteria. Proteobacteria was the most abundant prokaryotic phylum, accounting for 35.2-58.6% of the soil prokaryotes. The results are shown in Table 2. The soil fungal community mainly included Mucoromycota, Ascomycota and Basidiomycota. Mucoromycota was the most abundant fungal phylum, accounting for 39.35-77.98% of the soil fungal community. The results are shown in Table 3. Through the correlation analysis between soil potential toxic elements (PT Es) and the top 10 dominant microorganisms, the following conclusions were drawn: at the phylum level, the prokaryotic organism Proteobacteria had a significant enrichment effect on Cr, but showed a significant decomposition effect on Cd, Verrucomicrobia had a significant decomposition effect on Cr, and Chloroflexi had a significant decomposition effect on Hg. Among fungi, Basidiomycota had a significant decomposition effect on Cr, while Chytridiomycota had a significant decomposition effect on Hg.

[0050] Results Tables 4 and 5 show that at the genus level, the prokaryotes g_unclassified_c_Betaproteobacteria had a significant enrichment effect on Cr, while g_Bradyrhizobium showed a significant decomposition effect on Cr, g_unclassified_p_Candidatus_Rokubacteria had a significant enrichment effect on Hg, and g_unclassified_p_Chloroflexi showed a significant decomposition effect on Hg. Among fungi, only g_Diversispora had a significant decomposition effect on Hg, g_Glomus had a significant decomposition effect on Cd, and g_Penicillium, g_Aspergillus and g_Gigaspora had significant effects on the decomposition and enrichment of As, respectively.

[0051] Table 2 Relative abundance of prokaryotes under different management measures in alpine meadows

[0052]

[0053]

[0054] Table 3 Relative abundance of fungi under different management measures in alpine meadows

[0055]

[0056] Table 4 Relative abundance of prokaryotic genera under different management measures in alpine meadows

[0057]

[0058] Table 5 Relative abundance of fungal genera under different management measures in alpine meadows

[0059]

[0060]

[0061] The values ​​in Tables 2 to 5 are mean ± standard error of the mean (n = 3). After Duncan's post hoc test, different lowercase letters a and b indicate significant differences among different treatment groups (P < 0.05).

[0062] In summary, different grassland management strategies have produced significant effects in many aspects. On the one hand, these management measures have effectively changed the composition and distribution of surface vegetation communities, and at the same time have significantly adjusted the distribution of three potentially toxic elements, Cr, Hg, and As, in the soil, reducing their content levels in the soil. On the other hand, these measures have profoundly affected the abundance and community structure of dominant microbial community phyla and genera in the soil. Among them, specific dominant microbial community phyla and genera fully exert their unique functions and actively participate in the enrichment and decomposition of Cr and Hg, thereby effectively regulating the carbon metabolism process of the alpine meadow located on the southern foot of the Qilian Mountains on the Qinghai-Tibet Plateau. This series of changes is not only of great significance to the ecosystem health of the alpine meadow, but also provides a very valuable practical basis and theoretical foundation for exploring sustainable grassland management models and deeply understanding the internal operating mechanism of the alpine meadow ecosystem.

[0063] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for reducing the content of toxic elements Cr, Hg and As in alpine meadow soil, characterized in that: The methods include enclosure management, winter grazing or artificial monoculture of oats in alpine meadows.

2. The method according to claim 1, characterized in that The alpine meadows include alpine grass Kobresia dwarf meadows at an altitude of more than 3,200 meters on the Qinghai-Tibet Plateau.

3. The use according to claim 1, characterized in that: The enclosure management described above involves fencing off the alpine meadow, prohibiting grazing all year round, and the enclosure period is 12 years.

4. The method according to claim 1, characterized in that: The winter grazing method includes adopting the baby's breath style grazing from October of each year to May of the following year.

5. The method according to claim 1, characterized in that The method for artificial single sowing of oats comprises planting oats on a grassland, and applying organic fertilizers and removing stubbles in the planting process.

6. The method according to any one of claims 1 to 5 is used for regulating the abundance of dominant bacteria and / or increasing the organic carbon content in alpine meadow soil.

7. The use according to claim 6, characterized in that: The dominant bacterial community in the soil includes prokaryotes or fungi; the prokaryotes phylum level includes Proteobacteria, Verrucomicrobia, and Chloroflexi; the fungi phylum level includes Basidiomycota and Chytridiomycota.

8. The use according to claim 7, characterized in that: In the prokaryotic phylum level, Proteobacteria has an enrichment effect on Cr, Verrucomicrobia has a decomposition effect on Cr, and Chloroflexi has a decomposition effect on Hg; in the fungal phylum level, Basidiomycota has a significant decomposition effect on Cr, and Chytridiomycota has a significant decomposition effect on Hg.

9. The use according to claim 7, characterized in that: The dominant prokaryotic flora in the soil include g_unclassified_c_Betaproteobacteria, g_Bradyrhizobium, g_unclassified_p_Candidatus_Rokubacteria, and g_unclassified_p_Chloroflexi at the genus level; the dominant fungal flora in the soil include g_Diversispora, g_Glomus, g_Penicillium, g_Aspergillus, and g_Gigaspora at the genus level.

10. The use according to claim 9, characterized in that: In the prokaryotic genus level, g_unclassified_c_Betaproteobacteria has an enrichment effect on Cr, g_Bradyrhizobium has a significant decomposition effect on Cr, g_unclassified_p_Candidatus_Rokubacteria has an enrichment effect on Hg, and g_unclassified_p_Chloroflexi has a significant decomposition effect on Hg; in the fungal genus level, g_Diversispora has a significant decomposition effect on Hg, g_Glomus has a significant decomposition effect on Cd, and g_Penicillium, g_Aspergillus and g_Gigaspora all have significant decomposition and enrichment effects on As.

Images