CN115058250A - A kind of riparian soil matrix improvement method - Google Patents

Abstract

The invention provides a method for improving a soil matrix of a riparian zone, and relates to the technical field of soil matrix improvement. The invention adds gravel, ceramsite and biochar into the riparian zone soil according to a certain proportion to obtain the improved matrix. The results show that the denitrification effect in winter in reed areas of riparian zones can be improved through matrix improvement, the content of all carbon, all nitrogen and all phosphorus in soil is increased, certain correlation exists in the soil-plant stoichiometric characteristics obtained through further analysis, the relation between the soil and the stoichiometric characteristics of stems and roots is larger, and the fact that the denitrification effect in winter in the matrix improvement riparian zones is more easily influenced by the stoichiometric characteristics of the soil compared with plants is indicated. The research result of the invention can provide scientific reference for the protection and restoration of the reed area of the riparian zone and the prevention and control of non-point source pollution, and is helpful for better understanding the biogeochemical cycle of carbon, nitrogen and phosphorus of the riparian zone.

Description

A kind of riparian zone soil matrix improvement method

technical field

The invention relates to the technical field of soil matrix improvement, in particular to a soil matrix improvement method in a riparian zone.

Background technique

The riparian zone is the transition area between the terrestrial ecosystem and the aquatic ecosystem, which can effectively intercept the terrestrial pollutants from entering the water body, and is an important barrier for the land-water interface. In recent years, due to the excessive use of nitrogen fertilizers, excess reactive nitrogen has entered the catchment water through the process of runoff and seepage, resulting in eutrophication of the water body. The riparian zone can control the migration of nitrogen to the water body through the comprehensive action of "soil-plant-microbe", which plays a key role in the control of nitrogen non-point source pollution.

Reed (Phragmites australis), as one of the main plants in wetland ecosystems, has strong adaptability and wide ecological range, and is widely distributed in the global coastal zone. The denitrification efficiency of reed wetlands is very high, but it is significantly reduced in winter; studies have shown that the winter wheat season has more runoff total nitrogen loss than the rice season, so the nitrogen non-point source pollution generated in winter cannot be ignored. The soil matrix is an important part of the riparian zone, and it is also the carrier of plant growth. It can retain nitrogen through adsorption, precipitation, ion exchange, etc. The improvement of the soil matrix by adding different matrices can not only increase the pollutants in the matrix itself. The removal effect can also optimize the substrate environmental conditions required for plant growth, which may improve the denitrification effect of the riparian reed area in winter. In addition, as the main components of the riparian zone, the ecological stoichiometric characteristics (C, N, P contents and C/N, N/P, C/P ratios) of soil-plants may be affected by nitrogen non-point source pollution, This led to changes in the relationship and ratio of elements among components, which also affected the denitrification efficiency and nutrient cycling in the riparian zone. Previous studies on substrate improvement were mostly considered from the perspective of pollutant removal effect, and did not fully consider the nutrient distribution of the entire system and the differences and interactions of soil-plant stoichiometric characteristics. Therefore, exploring the effect of substrate improvement on the denitrification effect of riparian reed areas in winter, as well as the changes in soil-plant CNP stoichiometric characteristics, will help to better understand the CNP biogeochemical cycle in riparian zones, and will also provide important information for riparian restoration and Conservation provides scientific reference.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a riparian zone soil matrix improvement method. The present invention adds efficient, easy-to-obtain and safe gravel, ceramsite, and biochar substrates to the riparian zone soil, effectively exerting the complementary effect between the matrix combinations and combining with plants and plants. The advantages of synergy between microorganisms can improve the soil matrix environment of the riparian zone, which can effectively improve the denitrification effect of the riparian zone in winter.

In order to achieve the above-mentioned purpose of the invention, the present invention provides the following technical solutions:

The invention provides a method for improving a riparian soil matrix. The riparian soil is uniformly mixed into gravel and/or ceramsite in a volume ratio of 1:0.5 to 2, and 30 to 40% of the volume is uniformly mixed into a 20 to 30 cm soil layer. bio-charcoal.

In the present invention, the riparian vegetation community is reed.

In the present invention, the biochar includes one or more of corn stover charcoal, peanut shell charcoal, corncob charcoal, and coconut shell charcoal.

In the present invention, the particle size of the gravel and/or ceramsite is 1-2 cm.

In the present invention, the particle size of the biochar is 2-4 mm.

In the present invention, the ceramsite includes modified ceramsite.

In the present invention, the components of the modified ceramsite include one or more of TiO ₂ , SiO ₂ , CaO, and Al ₂ O ₃ .

In the present invention, the improvement includes increasing the removal rate of total nitrogen content, ammonium nitrogen removal rate and nitrate nitrogen removal rate in riparian water; increasing the total carbon content, total nitrogen content and total phosphorus content of wetland soil, and reducing the ratio of carbon to phosphorus and Nitrogen to phosphorus ratio; increase root carbon content and leaf nitrogen content of riparian vegetation.

Compared with the prior art, the present invention has the following technical effects:

(1) Compared with the control, the substrate improvement treatment of the present invention can effectively improve the denitrification effect in the riparian reed area in winter, wherein the average removal rate of total nitrogen content in the riparian water body is increased by 0.8% to 9.0%, and the average NH ₄ ⁺ -N The removal rate was increased by 6.1% to 9.0%, and the average removal rate of NO ₃ ^- -N was increased by 10.5% to 13.0%.

(2) Compared with the control, the substrate improvement treatments of the present invention all increased the soil total carbon content and total phosphorus content, and the differences between the treatments with gravel, gravel+biochar and improved ceramsite+biochar were significant (P<0.05) , indicating that substrate improvement can increase the accumulation of soil total carbon content and total phosphorus content. The matrix improvement treatment also increased the total nitrogen content of the soil, and the gravel + biochar treatment had a significant difference (P<0.05), which increased the effective accumulation of nitrogen, indicating that the matrix improvement could increase the effective adsorption of the soil and improve the buffer capacity of the soil.

(3) Soil C/P ratio is an important indicator of P availability. The lower the C/P ratio, the higher the P availability. The soil N/P ratio is a predictor of nutrient limitation and an important factor in judging N saturation. index. Compared with the soil matrix, the soil C/P and N/P ratios of the matrix improvement treatment of the present invention both tended to decrease, and the gravel addition treatment was significantly different (P<0.05), indicating that the soil P in the matrix improvement treatment was relatively effective. higher, it still behaves as N-limited and can be affected by higher nitrogen concentrations in the Na riparian waters.

(4) The addition of ceramsite + biochar and improved ceramsite + biochar to the matrix of the present invention has a promoting effect on plant growth, and the absorption of C and N is relatively large.

(5) The present invention analyzes the soil-plant ecological stoichiometric characteristics of the improved substrate, and the results show that there is a certain correlation in the soil-plant stoichiometric characteristics, and the relationship between soil and stem and root is greater; compared with plants, Substrate improvement made the denitrification effect of the riparian reed region more susceptible to soil stoichiometric characteristics in winter. The research results can provide scientific reference for the protection and restoration of the riparian reed area and the prevention and control of non-point source pollution, and help to better understand the biogeochemical cycle of carbon, nitrogen and phosphorus in the riparian zone.

Description of drawings

Fig. 1 is a schematic diagram of an experimental device for simulating a reed wetland in a riparian zone;

Fig. 2 is a graph showing the change of the in and out water concentrations of TN, NH ₄ ⁺ -N and NO ₃ ^- -N;

Fig. 3 is a graph showing the removal rates of TN, NH ₄ ⁺ -N and NO ₃ ^- -N;

Fig. 4 is soil TC, TN, TP content map;

Figure 5 is a diagram of soil CNP stoichiometric ratio;

Fig. 6 is C, N, P content figure of each organ of plant;

Fig. 7 is C, N, P stoichiometric ratio diagram of each organ of plant;

Figure 8 is a correlation diagram of soil-plant C, N, and P stoichiometric characteristics, wherein, S-TC: soil total carbon content, S-TN: soil total nitrogen content, S-TP: soil total phosphorus content, S-C/N : soil carbon and nitrogen ratio, S-C/P: soil carbon and phosphorus ratio, S-N/P: soil nitrogen and phosphorus ratio, L-C: leaf carbon content, L-N: leaf nitrogen content, L-P: leaf phosphorus content, L-C/N: leaf carbon and nitrogen ratio , L-C/P: leaf carbon and phosphorus ratio, L-N/P: leaf nitrogen and phosphorus ratio, St-C: stem carbon content, St-N: stem nitrogen content, St-P: stem phosphorus content, St-C/N: stem Carbon to nitrogen ratio, St-C/P: stem carbon to phosphorus ratio, St-N/P: stem nitrogen to phosphorus ratio, R-C: root carbon content, R-N: root nitrogen content, R-P: root phosphorus content, R-C/N: root carbon Nitrogen ratio, R-C/P: root carbon-phosphorus ratio, R-N/P: root nitrogen-phosphorus ratio;

Figure 9 is an RDA analysis diagram of water quality factors, soil-plant stoichiometric characteristics and wetland denitrification effects, where r(TN): wetland TN removal rate, r(NH ₄ ⁺ -N): wetland NH ₄ ⁺ -N removal rate, r(NO ₃ ^- -N): removal rate of wetland NO ₃ ^- -N.

Detailed ways

The invention provides a method for improving a riparian soil matrix. The riparian soil is uniformly mixed into gravel and/or ceramsite in a volume ratio of 1:0.5 to 2, and 30 to 40% of the volume is uniformly mixed into a 20 to 30 cm soil layer. bio-charcoal. Preferably, the riparian soil is uniformly mixed with gravel and/or ceramsite in a volume ratio of 1:0.8-1; preferably, 32%-38% of biochar by volume is uniformly mixed in a 22-26cm soil layer. As an important part of riparian wetlands, soil matrix can cooperate with the interaction of plants and microorganisms to have an important impact on the migration and transformation of riparian nitrogen. The research of the present invention shows that by adding an appropriate amount of high-efficiency, easy-to-obtain and safe gravel, ceramsite, and biochar, the complementary effect between matrix combinations and the advantages of synergy with plants and microorganisms can be effectively exerted, and the pollutant removal effect of the riparian zone can be improved. . In the present invention, the sources of the gravel, ceramsite, and biochar are not particularly limited, and commercially available products can be used.

In the present invention, the riparian vegetation community is reed. In a specific embodiment of the present invention, the basic physical and chemical properties of the riparian soil are organic carbon 7.3 g·kg ^-1 , total nitrogen 0.4 g·kg ^-1 , total phosphorus 0.6 g·kg ^-1 , and pH 7.0.

In the present invention, the biochar includes one or more of corn stover charcoal, peanut shell charcoal, corncob charcoal, and coconut shell charcoal. In the present invention, evenly mixing biochar into the 20-30cm soil layer will further improve the denitrification efficiency of the wetland, and the biochar has a better adsorption effect on NH ₄ ⁺ -N, providing a carbon source for microbial denitrification. Meanwhile, the treatment of adding biochar was beneficial to plant root C fixation and plant N uptake.

In the present invention, the particle size of the gravel and/or ceramsite is 1-2 cm. In the present invention, adding gravel and/or ceramsite matrix increases the permeability of the matrix, affects the water transport process in the matrix and the microenvironment of plant root-microbe growth, thereby indirectly affecting the denitrification effect of the riparian zone ; In addition, the irregular geometry of gravel and/or ceramsite adds to the complex structure of the microenvironment, and more effectively plays the role of plant root-microbes.

In the present invention, the particle size of the biochar is 2-4 mm.

In the present invention, the ceramsite includes modified ceramsite. In the present invention, adding modified ceramsite has a promoting effect on plant growth. The source of the modified ceramsite is not particularly limited in the present invention, but in a specific embodiment of the present invention, the modified ceramsite is purchased from a science and technology company in Jiangxi, and the modified ceramsite is made of silicon-titanium supermaterial, It is composed of silicon-titanium metamaterial composite composite material.

In the present invention, the components of the modified ceramsite include one or more of TiO ₂ , SiO ₂ , CaO, and Al ₂ O ₃ .

In the present invention, the improvement includes increasing the removal rate of total nitrogen content, ammonium nitrogen removal rate and nitrate nitrogen removal rate in riparian water; increasing the total carbon content, total nitrogen content and total phosphorus content of wetland soil, and reducing the carbon-to-phosphorus ratio and nitrogen-phosphorus ratio; increase root carbon content and leaf nitrogen content of riparian vegetation. In the present invention, the average removal rate of total nitrogen content in riparian water bodies is increased by 0.8% to 9.0%, the average removal rate of ammonium nitrogen is increased by 6.1% to 9.0%, and the average removal rate of nitrate nitrogen is increased by 10.5% to 13.0%, indicating that the substrate is improved. It can effectively improve the denitrification effect of the riparian reed area in winter.

Soil C, N, P contents and their stoichiometric ratios are important indicators to characterize soil quality and nutrient balance, and are of great significance to carbon, nitrogen, and phosphorus cycles. In the present invention, the substrate improvement treatment both increased the soil total carbon content and the total phosphorus content, indicating that the substrate improvement can increase the accumulation of the soil total carbon content and total phosphorus content; the substrate improvement treatment also increased the soil total nitrogen content and increased nitrogen content. The effective accumulation of , indicating that matrix improvement can increase the effective adsorption of the soil and improve the buffer capacity of the soil.

Soil C/P ratio is an important indicator of P availability. The lower the C/P ratio, the higher the P availability. The soil N/P ratio is a predictor of nutrient limitation and an important indicator for judging N saturation. In the present invention, the soil C/P and N/P ratios of the matrix improvement treatment are both decreasing, indicating that the P availability in the matrix improvement treatment soil is relatively high, and it is still limited by N, which can be tolerated by the wetland influent more. high nitrogen concentration.

C, N and P in plants are important nutrient elements for their growth and development. Among them, C is the basic element of plant dry matter composition, and N and P are one of the important indicators reflecting plant growth status; the plant CNP ratio reflects its environmental impact. The adaptation mechanism and characteristics, the stoichiometric ratio of different organs can also reflect the organ homeostasis and the distribution and interrelation of elements in different organs, and play an important role in predicting ecosystem changes. In the present invention, the substrate improvement changes the C, N, and P contents in plant leaves and roots, mainly increasing the root carbon content, indicating that adding biochar to the substrate is more conducive to the carbon fixation of roots; in addition, gravel + biochar Treatment significantly increased leaf nitrogen content.

The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some, but not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

Example 1

The experiment was carried out in the subtropical region by simulating the reed wetland in the riparian zone, and 20 potted plants with the same structure were constructed, in the shape of a cylinder with a diameter of 30cm and a height of 50cm. Maintain a fixed water level. In order to facilitate the determination of the in-situ water quality index and water pumping inside the system, a perforated pipe with an inner diameter of 5 cm was vertically arranged in the center of the device.

The riparian soil was evenly mixed into the gravel at a volume ratio of 1:1, and 33.3% volume of biochar was evenly mixed into the 20cm soil layer, and 4 replicates were set. Plant plants while filling the substrate, that is, in June 2019, select reed seedlings with similar growth vigor and transplant them into the device. The initial planting density is 2 plants·pot ^-1 . The reeds are cultivated in the device. Average growth is stable.

The simulated wetland was established and operated in the Zhuanghang Comprehensive Test Base (30°53′N, 121°23′E) of the Shanghai Academy of Agricultural Sciences. After the system was stable for at least 4 months, the experiment officially started, from the end of October 2019 to 2020 The end of March, covering the entire winter. The system is filled with water once a week, and it is completed around 10 am. Before each water entry, the water quality index inside the system is measured in situ in the perforated pipe, and the water in the device is drained and water samples are taken, and then the next one is carried out. into the water. After the end of the operation, the device was subjected to destructive sampling, and the soil samples in the plants (leaves, stems, roots) and substrates were collected at the same time, and their carbon, nitrogen and phosphorus contents were determined.

Example 2

The difference from Example 1 is that the riparian soil is evenly mixed into the ceramsite at a volume ratio of 1:1, and the remaining steps are the same as those in Example 1.

Example 3

The difference from Example 1 is that the riparian soil is uniformly mixed into the modified ceramsite at a volume ratio of 1:1, and the remaining steps are the same as those in Example 1.

Example 4

The difference from Example 1 is that the riparian soil is uniformly mixed into the gravel at a volume ratio of 1:0.5, and 30% of the volume of biochar is uniformly mixed into the 20cm soil layer. The remaining steps are the same as in Example 1.

Example 5

The difference from Example 1 is that the riparian soil is uniformly mixed into the gravel at a volume ratio of 1:2, and 40% of the volume of biochar is uniformly mixed into the 20cm soil layer. The remaining steps are the same as in Example 1.

Example 6

The difference from Example 1 is that the riparian soil is evenly mixed into the gravel at a volume ratio of 1:1, and 33.3% of the volume of biochar is evenly mixed into the 25cm soil layer. The remaining steps are the same as those in Example 1.

Example 7

The difference from Example 1 is that the riparian soil is evenly mixed into the gravel at a volume ratio of 1:1, and 33.3% biochar by volume is evenly mixed into the 30cm soil layer, and the remaining steps are the same as those in Example 1.

Comparative Example 1

The difference from Example 1 is that the riparian soil is not mixed with any substrate, and the rest of the steps are the same as in Example 1.

Comparative Example 2

The difference from Example 1 is that the riparian soil is evenly mixed into the gravel at a volume ratio of 1:1, and no biochar is added to the 20-30 cm soil layer, and the remaining steps are the same as those in Example 1.

Example 8

Measurement indicators and methods:

Use a portable multi-parameter water quality analyzer (HI9829, HANNA, Italy) to measure the basic water quality indicators inside the system, including temperature, pH, dissolved oxygen, redox potential, total dissolved solids, and electrical conductivity; Potassium sulfate oxidation method; _NH4 ⁺ -N and _NO3 ^-- N concentrations were determined using a flow analyzer (AA3, Seal, Germany).

The total carbon and total nitrogen contents of the soil were determined by an element analyzer (Vario EL cube, Elementar, Germany); the total phosphorus content was determined by the perchloric acid-sulfuric acid method.

The leaves, stems and roots of the plants were fixed in an oven, dried to constant weight, and the plant biomass was weighed; the carbon and nitrogen contents were measured by an element analyzer (Vario EL cube, Elementar, Germany); the phosphorus content was measured by the molybdenum-antimony ratio Color measurement.

Data statistics and analysis software:

IBM SPSS 22.0 software was used to process the data, one-way ANOVA and significant difference test (Duncan, P<0.05) were performed; SigmaPlot 12.5 software was used to make graphs, and the data in the graph were mean ± standard deviation; R4.1.1 draws Pearson correlation heat map; Canoco5.0 software is used for redundancy analysis (RDA).

Result and analysis of denitrification effect in winter in riparian reed area:

It can be seen from Fig. 2 that during the experiment, the total nitrogen concentration of the influent water of the system was 5.8-20.7 mg·L ^-1 , the NH ₄ ⁺ -N concentration was 0.3-14.4 mg·L ^-1 , and the NO ₃ -N concentration was 0.1-1.2 mg ·L ^-1 , the influent concentration fluctuated relatively large, and the effluent concentration decreased significantly and remained relatively stable at a low level.

According to Fig. 3, it can be seen that during the experiment, the removal rates of TN and NH ₄ ⁺ -N were different between treatments (P<0.05), while the removal rates of NO ₃ ^- -N were not significantly different (P>0.05). From the point of view of the average removal rate of TN, Example 1 (shown on the abscissa DS3) is the highest at 97.2% and is relatively stable; followed by Example 2 (shown on the abscissa DS4), which is 94.2%; Comparative Example 1 (shown on the abscissa DS1) shown) was 88.3% relatively low and unstable, which was significantly different from Example 1 (P<0.05). From the average removal rate of NH ₄ ⁺ -N, Example 1 is relatively high and stable at 97.9%; followed by Example 2 at 95.3% and Example 3 (as shown by abscissa DS5) at 95.1%; Comparative Example 1 It was 89.0%, which was relatively low and unstable, and was significantly different from Example 1 (P<0.05). In terms of the average removal rate of NO ₃ ^- -N, although the difference between treatments was not significant (P>0.05), the removal rates of Examples 1 to 3 were higher and relatively stable than those of Comparative Example 1.

Compared with Comparative Example 1, the average removal rates of TN in Comparative Example 2 (shown on the abscissa DS2), Example 1, Example 2 and Example 3 were higher by 5.5%, 8.9%, 5.9%, and 0.8%, respectively. The average removal rates of ₄ ⁺ -N were 8.3%, 8.9%, 6.4% and 6.1% higher, and the average removal rates of NO ₃ ^- -N were 13.0%, 12.5%, 11.4% and 10.5% higher, respectively.

It can be seen from Table 1 that there is little difference in T and DO of water in different treatment systems, while pH, ORP, EC and TDS all have differences between treatments. The pH of Comparative Example 2 and Examples 1 to 3 were significantly higher than those of Comparative Example 1 (P<0.05), and there was also a significant difference between Example 1 and Example 3 and Comparative Example 2 and Example 2 (P<0.05) . Compared with Comparative Example 1, the ORP of Examples 1 to 3 was significantly decreased (P<0.05), while the EC and TDS were significantly increased (P<0.05), and the trends between treatments were the same.

Table 1 In-situ water quality indicators in the system

Analysis of soil stoichiometric characteristics results:

According to the content of soil nutrients (TC, TN, TP) in Figure 4, it can be seen that compared with Comparative Example 1 (shown on the abscissa DS1), Comparative Example 2 (shown on the abscissa DS2) and Examples 1 to 3 ( The soil TC content of the abscissa (DS3-DS5) has an increasing trend, and the increase in Example 3 is relatively the largest (P<0.05), and there is also a significant difference in Example 1 (P<0.05); Comparative Example 2 and Example 1-implementation The soil TN content of Example 3 has an increasing trend, the difference between Example 1 and Comparative Example 1 is significant (P<0.05), and Example 3 has little change; the soil TP content of Comparative Example 2 and Examples 1 to 3 all increased Trend, Example 3 increased the relative maximum (P<0.05), Example 1 also had a significant difference (P<0.05).

According to the soil CNP stoichiometric ratio in Figure 5, it can be seen that compared with Comparative Example 1 (shown on the abscissa DS1), the soil C/N ratio of Example 3 (shown on the abscissa DS5) was significantly increased (P<0.05), Examples 1-2 (shown on the abscissa DS3-DS4) did not change much; the soil C/P and N/P ratios of Examples 1-3 had a decreasing trend, and the soil N/P ratio of Example 3 was different from DS1 Significant (P<0.05).

Analysis of phytostoichiometric characteristics results:

According to Fig. 6 the nutrient (C, N, P) contents of each organ of reed, it can be seen that compared with leaves and roots, the C, N, P contents of stems have no significant difference between treatments (P>0.05). Compared with the leaves and stems, the C content in the roots changed relatively greatly between treatments, and compared with the comparative example 1 (shown on the abscissa DS1), Examples 1 to 3 (shown on the abscissa DS3 ~ DS5) all significantly increased. The root C content (P<0.05), while the leaf C content of Example 1 was significantly reduced (P<0.05); the leaf N content was higher than that of the stem and root, compared with the comparative example, the leaf N content of Example 1 was significantly increase (P < 0.05), the root N content of Example 2 and Example 3 increased significantly (P < 0.05); except that the leaf P content of Comparative Example 2 (as shown by the abscissa DS2) was significantly decreased (P < 0.05), The trend of P content in each organ was leaf>root>stem.

According to the CNP stoichiometric ratio of each organ of reed in Figure 7, it can be seen that the C/N, C/P and N/P ratios of stems and roots were not significantly different between treatments (P>0.05). Compared with the leaves of Comparative Example 1 (C/N 21.3, C/P 361.7, N/P 16.9), the leaf C/N ratio (14.8) of Example 1 was significantly lower (P<0.05), while the leaves of Comparative Example 2 The leaf C/P ratio (660.8) and N/P ratio (28.6) were significantly increased (P<0.05).

According to Table 2, it can be seen that the nutrient distribution of plants in the system is calculated from the biomass and C, N, and P contents of various plant organs. From the average of the total biomass, compared with Comparative Example 1, Example 1 showed a decreasing trend, Examples 2-3 showed an increasing trend, and Example 1 had a significant difference (P<0.05), mainly stem biomass significantly reduced impact. Compared with Comparative Example 1, the inter-treatment trend of total plant C in the system was consistent with the biomass trend, but the difference was not significant (P>0.05). The inter-treatment trend of the total amount of plant N in the system was also consistent with the biomass trend, and Example 2 and Example 3 showed a significant level of difference (P<0.05). Compared with Comparative Example 1, the leaves, stems, The amount of C in roots all increased (P<0.05), while the amount of C in leaves and roots of Example 3 increased significantly, but the amount of C in stems decreased significantly (P<0.05). Compared with Comparative Example 1, the total amount of plant P in Examples 1 to 3 and Comparative Example 2 had a decreasing trend, but the difference was not significant (P>0.05).

Table 2 Nutrient distribution of plants in the system (unit: g·pot ^-1 )

Soil-plant stoichiometric characteristics correlation analysis:

CNP stoichiometric characteristics can be used as an effective tool to analyze the coupling relationships and differences between elements in soil-plant systems. According to the Pearson correlation analysis between the stoichiometric characteristics of soil and plant organs in Figure 8, the correlation between the nutrient content and stoichiometric ratio of soil, leaves, stems, and roots is greater. Between soil and plants, soil TC content was only correlated with root C content (R=0.54, P<0.05); soil TN content was positively correlated with stem and root N content, and negatively correlated with stem and root C/N ratio (P<0.05); the correlation between soil TP content and C/P ratio and the stoichiometric characteristics of plant organs was small (P>0.05); soil C/N ratio was mainly related to the stoichiometric characteristics of stems, and The N and P contents of the stem were negatively correlated, and the C/N and C/P ratios were positively correlated (P<0.05). <0.05).

Among plant organs, only roots and leaves have stoichiometric correlations, root C content is positively correlated with leaf P content (P<0.05), and negatively correlated with leaf C/P and N/P ratios (P<0.05). 0.01); root C/P ratio was negatively correlated with leaf N/P ratio (P<0.05).

According to the RDA analysis in Figure 9, the temperature and pH in the water quality factors have an impact on the change of the wetland denitrification efficiency during the experiment, and the temperature is negatively correlated, and the pH is positively correlated; generally speaking, the higher the temperature, the better the wetland denitrification effect in winter. The better, in the present invention, the temperature difference between the treatments in each example is not large, indicating that the substrate improvement does not improve the denitrification effect of wetlands in winter by affecting the temperature; the system pH of the substrate improvement treatment is significantly increased, and the present study shows that the low temperature The higher the pH within a certain range, the better the denitrification effect; under the condition of alkaline pH, if there is enough NH ₄ ⁺ -N and good aeration conditions, NH ₄ ⁺ -N can be rapidly converted by nitrification It is NO ₃ ^- -N, indicating that the increase of pH may be an important factor for improving the denitrification effect of wetland by substrate improvement.

The above are only the preferred embodiments of the present invention. It should be pointed out that for those skilled in the art, without departing from the principles of the present invention, several improvements and modifications can be made. It should be regarded as the protection scope of the present invention.

Claims (8)

1. a riparian zone soil matrix improvement method is characterized in that, the riparian zone soil is evenly mixed into gravel and/or ceramsite by volume ratio 1:0.5～2, and 30%～40% is evenly mixed into 20～30cm soil layer volume of biochar. 2. The method according to claim 1, wherein the riparian vegetation community is reed. 3. The method according to claim 1, wherein the biochar comprises one or more of corn stover charcoal, peanut shell charcoal, corncob charcoal, and coconut shell charcoal. 4. The method according to claim 1, wherein the particle size of the gravel and/or ceramsite is 1-2 cm. 5 . The method according to claim 3 , wherein the particle size of the biochar is 2˜4 mm. 6 . 6. The method of claim 1, wherein the ceramsite comprises modified ceramsite. 7 . The method according to claim 6 , wherein the components of the modified ceramsite include one or more of TiO ₂ , SiO ₂ , CaO, and Al ₂ O ₃ . 8. The method according to claim 1, wherein the improvement comprises increasing the removal rate of total nitrogen content, ammonium nitrogen removal rate and nitrate nitrogen removal rate in riparian water; increasing the total carbon content, total nitrogen content of wetland soil content and total phosphorus content, reduce the carbon-to-phosphorus ratio and nitrogen-to-phosphorus ratio; increase the root carbon content and leaf nitrogen content of riparian vegetation.

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