CN108031706B

CN108031706B - Soil conditioner for restoring Cd pollution of soil and application thereof

Info

Publication number: CN108031706B
Application number: CN201711093771.XA
Authority: CN
Inventors: 张奇春; 蔡梅; 邸洪杰
Original assignee: Zhejiang University ZJU
Current assignee: Zhejiang University ZJU
Priority date: 2017-11-08
Filing date: 2017-11-08
Publication date: 2020-04-24
Anticipated expiration: 2037-11-08
Also published as: CN108031706A

Abstract

The invention relates to soil pollutionThe invention belongs to the technical field of dyeing improvement and restoration treatment, and particularly discloses a soil conditioner for restoring Cd pollution of soil, which comprises the following components in parts by weight: 45-49% of lime, 45-49% of zeolite, 4-6% of perphosphate and 0.8-1.2% of biomass charcoal. The invention also discloses an application method of the soil conditioner for remedying the Cd pollution of the soil, which comprises the following steps: uniformly applied into soil, and the addition amount is 1.25 kg.m^‑2～5kg·m^‑2. In the soil with severe cadmium pollution, the application of the modifier can effectively reduce the effective state content of Cd in the soil, reduce the content of cadmium in the brown rice of rice, and simultaneously can improve the rice yield to reach the national food sanitation standard.

Description

Soil conditioner for restoring Cd pollution of soil and application thereof

Technical Field

The invention relates to the technical field of soil pollution improvement and restoration treatment, in particular to improvement and restoration treatment of Cd pollution in soil heavy metal pollution.

Background

With the progress of modern society, cadmium is widely applied in nuclear industry, battery industry, electroplating industry, plastic industry and the like, and enters soil through atmospheric sedimentation and human production activities, so that Cd pollution to the soil becomes a serious problem. Meanwhile, cadmium is a pollution element with extremely strong seed toxicity, has serious harm to human bodies, animals and plants, and has strong mobility and biological enrichment. The Cd pollution condition of the soil in China is not optimistic, and the beyond-standard rate of the point position of the cadmium pollutant is shown to reach 7.0% in 2014 national soil pollution condition survey bulletin. From 20 th century 80 th Japan bone pain caused by irrigating farmlands with cadmium-containing wastewater to 2013 Hunan cadmium rice, cadmium pollution frequently occurs, and the alarm clock is sounded for food safety problems.

Aiming at the treatment of cadmium-polluted soil, the soil conditioner is regarded as a relatively economic and convenient soil remediation method. The soil conditioner is generally divided into four categories of natural conditioners, synthetic conditioners, natural-synthetic copolymer conditioners and biological conditioners according to the raw material sources, wherein the natural conditioners are widely applied. Common natural modifiers include lime, zeolite, biomass charcoal, bentonite, vermiculite, peat, and the like. Meanwhile, the fertilization has certain influence on the absorption of cadmium by plants, and a large number of researches show that calcium, magnesium, phosphorus, calcium hydrogen phosphate and potassium dihydrogen phosphate are added into the soil to increase the pH value of the soil,thereby reducing the bioavailability of cadmium; and less reports have been made of the effectiveness of superphosphates in reducing heavy metals in soils. Because the condition of soil quality degradation is easy to occur when a single soil conditioner is used, the existing soil conditioner mostly adopts two or more conditioners for mixed combination use or the conditioner is matched with a fertilizer for use. It has been reported that the conversion of cadmium form in soil is studied by using natural zeolite and lime, and that lime (Ca (OH))₂) The combination effect of 2g/kg soil and zeolite (70% clinoptilolite) 60g/kg soil is the best, and the content of the cadmium in the soil in an exchange state can be reduced by 34.68%.

Disclosure of Invention

The invention aims to solve the technical problem of providing a soil conditioner for restoring Cd pollution of soil and application thereof.

In order to solve the technical problems, the invention provides a soil conditioner for restoring Cd pollution of soil, which comprises the following components in parts by weight: 45-49% of lime, 45-49% of zeolite, 4-6% of perphosphate and 0.8-1.2% of biomass charcoal.

The improvement of the soil conditioner for restoring Cd pollution of soil provided by the invention comprises the following components by weight: 47% lime, 47% zeolite, 5% superphosphate, and 1% biomass char.

The improvement of the soil conditioner for remedying the Cd pollution of the soil is as follows: the superphosphate is granular superphosphate, the lime is powdered calcium oxide, the zeolite is powdered artificial zeolite, and the biomass charcoal is prepared by heating bamboo in an oxygen-free closed container to 600 +/-50 ℃ for heat treatment for 2 hours.

The invention also provides an application method of the soil conditioner for remedying the Cd pollution of the soil, which comprises the following steps: uniformly applying into soil (uniformly mixing the modifier and soil by tillage technology), and adding 1.25 kg.m^-2～5kg·m^-2(corresponding to 0.5 to 2 percent of the weight ratio of the soil).

The application method of the soil conditioner for remedying the Cd pollution of the soil is further improved as follows: the preferred addition amount is 1.25kg · m^-2、2.5kg·m^-2(by soil weight)The quantitative ratio corresponds to 0.5%, 1%).

When the modifier is actually used, all components of the modifier are uniformly mixed, and then the modifier is applied to Cd-polluted soil and fully mixed with the soil. In the present invention, lime, zeolite, perphosphate and the like can be obtained by conventional commercially available forms.

In the present invention: the lime component in the conditioner can improve the pH value of soil, improve acid soil and reduce the effectiveness of heavy metal Cd; the zeolite has the capacity of preserving moisture and adsorbing heavy metals in soil. Biomass charcoal also has the ability to reduce the available state of heavy metals in soil. The superphosphate in the modifier is a fertilizer, so that the effective state of heavy metals in soil is reduced, and meanwhile, P can be provided for plants, and the biomass of the plants is increased. The modifier of the invention has low raw material price and is suitable for wide popularization. In the soil with severe cadmium pollution, the application of the modifier can effectively reduce the effective state content of Cd in the soil, reduce the content of cadmium in the brown rice of rice, and simultaneously can improve the yield of the rice, thereby achieving the national food sanitation standard.

Drawings

The following describes embodiments of the present invention in further detail with reference to the accompanying drawings.

FIG. 1 is a graph comparing the change in soil pH during 90 days of flooded culture;

FIG. 2 is a graph comparing the change in soil exchange state Cd during 90 days of flooding culture;

FIG. 3 is a graph comparing the effect of amendment on the exchange state Cd in soil during rice growth;

FIG. 4 is a graph showing the comparison of the total cadmium content in each part of rice.

Detailed Description

The invention is further illustrated below with reference to specific examples. The methods mentioned in the following examples are conventional methods unless otherwise specified, and the starting materials are commercially available materials unless otherwise specified.

Example 1, a soil conditioner for remediating Cd-contaminated soil, which consists of the following components in parts by weight: 47% lime, 47% zeolite, 5% superphosphate, and 1% biomass char.

The superphosphate is granular superphosphate; the lime is powdery calcium oxide; the zeolite is powdered artificial zeolite; the preparation method of the biomass charcoal comprises the following steps: placing bamboo into an oxygen-free closed container, heating to 600 ℃, and carrying out heat treatment for 2 hours to obtain biomass charcoal.

Experiment 1, application of conditioner to flooded culture of Cd-polluted soil

The improvement experiment is carried out in a 6-2016 and 11-2016 laboratory in the hong Kong school district of Zhejiang university, Hangzhou, Zhejiang province. The soil to be tested is rice field in western region of Hongkong school district of Zhejiang university of Hangzhou city, Zhejiang province, with pH of 6.52 and total cadmium of 0.02 mg.kg^-1. By adopting the culture experiment, each culture bucket air-dries the rice soil by 0.5kg, with CdSO₄Adding Cd20 mg-kg in the form of solution^-1And (3) uniformly mixing the soil, adjusting the water content of the soil to 60% of field water capacity, and stabilizing for one week. The levels of modifier addition were set to 0 (no soil modifier, CK), 0.5%, 1%, 2%, 4%, and 10%, respectively. Adding modifier, mixing, adding enough deionized water into each parallel sample to submerge soil surface and make surface water layer reach 1-2cm, culturing at room temperature, and adding water by weighing method during culturing process.

Note: according to the depth of 20cm of the cultivated layer, the volume weight of the soil is 1.25t/m³The amounts of 0.5%, 1%, 2%, 4% and 10% added were 1.25kg · m, respectively^-2、2.5kg·m^-2、5kg·m^-2、10kg·m^-2And 25kg m^-2。

The experimental results are as follows: the modifier is added into Cd-polluted soil, the pH value of the soil is obviously increased, and the larger the adding amount of the modifier is, the larger the pH value of the soil is increased (figure 1). On the 1 st day of the waterflooding culture, the pH values of the treatments increased to 12.22 and 11.96 with the addition of 10% and 4% of the modifier, respectively, and the pH values of the soils increased by 5.24, 4.98, 4.22, 2.49 and 1.51 with the addition of 10%, 4%, 2%, 1% and 0.5% of the modifier, respectively, compared with CK. After 90 days of culture, the pH value of each treatment is slowly reduced, the addition amount of the modifying agent is 2 percent, the maximum reduction is 1.18, and the addition amount of the modifying agent is 4 percent, and the reduction is 0.97.

The Cd-polluted soil can be added into the modifying agent, so that the content of the exchange state Cd in the soil can be obviously reduced (figure 2). After 90 days of culture, compared with CK, the addition amount of the modifying agent is 10%, 4%, 2%, 1% and 0.5% and the exchange state Cd are reduced by 98.77%, 98.03%, 98.13%, 89.49% and 75.55% in sequence. During 90 days of culture, the addition of the modifying agent is 1 percent, the reduction amplitude of the exchange state Cd is maximum, and is reduced by 80.25 percent, and the addition of the modifying agent is 0.5 percent, and is reduced by 80.25 percent.

From the results, the content of exchangeable Cd in the soil can be obviously reduced by adding 10% and 4% of the modifying agent, but the pH value of the soil is extremely easy to increase, so that the plant is not easy to survive, and the modifying agent is not suitable for practical popularization and application.

In order to find the amount of the amendment, i.e., the amount most suitable for both reducing the bioavailability of Cd in the soil and ensuring the normal growth of crops, the inventors performed a rice potting test as described in experiment 2 below.

Experiment 2, application of the improver of the invention in Cd-contaminated soil

1. Experimental conditions

The improvement experiment is carried out in a greenhouse in the hong Kong school district of Zhejiang university, Hangzhou, Zhejiang province from 3 months to 2017 months in 2017. The soil to be tested is rice soil taken from Yangxi town of Ningbo city, Zhejiang province, and the crops to be tested and cultivated are as follows: rice (variety name: Lingshangyou 7717).

TABLE 1 physicochemical Properties of the soil to be tested

A potting experiment was used. Loading 3kg of soil in each pot, manually adding cadmium sulfate solution, and adjusting the soil to Cd 10 mg/kg^-1Mixing with soil, and stabilizing for 2 weeks. The modifier is added in the amount of 0(CK), 0.5%, 1% and 2% as experimental group, and a group of complete blanks (CK0) is set, namely no Cd pollution and modifier are added. Repeat 3 times. Adding modifier according to different addition amounts, mixing well, addingAnd (5) ionizing water until the soil surface is submerged and the water layer reaches about 1cm, and transplanting rice seedlings after 1 month of submerged culture. Applying base fertilizer 7 days before transplanting rice, wherein the dosage of the base fertilizer is 0.77g of urea (N46%) and calcium superphosphate (P) added in each pot₂O₅12%) 1.84g and potassium chloride (K)₂O60%) 0.31 g. Transplanting 4 rice seedlings with the seedling age of about 30 days in each pot. 0.39g of urea is applied to each pot in the early tillering stage of the rice, and 0.39g of urea and 0.31g of potassium chloride are applied to each pot in the young ear differentiation stage. Keeping water layer 1-2cm in the whole growth period of rice, and irrigating with deionized water. Other management was consistent with the field throughout the growth period.

2. Results and analysis

2.1 Effect of different treatments on growth and yield of Rice

The rice is transplanted in a pot in 2017 in No. 4 and No. 24, and the fact that 2% of treated rice seedlings are short and weak compared with other treated rice seedlings is found in the growth period of the rice. The rice was harvested 93 days after transplantation.

Table 2 shows the biomass and yield of rice after harvesting, and compared with CK0 and CK, the addition amount of the modifying agent is 2%, the plant height, the dry weight of straws, the yield and the thousand-grain weight of rice are reduced, and the addition amount of the modifying agent is 0.5% and 1%, and the dry weight of straws and the yield of rice are increased.

TABLE 2 Biomass and yield of differently treated rice

Note: different letters in the same column indicate significant differences at the 5% level between treatments.

2.2 Effect of different treatments on soil-exchanged cadmium and Total cadmium content of Rice

As shown in figure 3, the content of exchangeable Cd in the soil is significantly reduced by adding the improver compared with CK, and the content of the exchanged Cd in the soil is less than 0.1 mg-kg during the whole growth period of the rice^-1。

Through the determination of the total cadmium content in the roots, straws and brown rice of the rice (figure 4), the total cadmium content of each part of the rice is found to be as follows in sequence: root of herbaceous plant>Straw and stalk>Brown rice. Is differentThe sequence of the addition amount of the modifying agent to the total Cd content in the rice straw and the brown rice is as follows: CK (CK)>0.5％>1％>2 percent. According to the regulation of GB2762-2012 limit of pollutants in food, the limit of Cd in the brown rice is 0.2 mg-kg^-1The content of all cadmium in the paddy brown rice added with the modifying agent in the experiment is higher than the national standard, but compared with CK, the content of all Cd in the paddy brown rice is sequentially reduced by 78.61%, 82.63% and 89.25% when the adding amount of the modifying agent is 0.5%, 1% and 2%, and the effect of reducing the content of Cd in the paddy brown rice by the modifying agent is remarkable.

According to the above, when the addition amount of the modifying agent is 0.5% and 1%, the content of Cd in the brown rice can be remarkably reduced, and the yield of rice can be increased. Meanwhile, the application of the conditioner disclosed by the invention has a good passivation effect on exchangeable Cd in soil, the content of Cd in brown rice of rice is remarkably reduced, and the risk of food safety of soil polluted by Cd in cultivation can be reduced.

Comparative example 1-1, the use of biomass charcoal was eliminated, i.e. the soil conditioner consisted of the following ingredients in weight content: 47% lime, 47% zeolite, 6% superphosphate, the remainder being identical to example 1.

Comparative examples 1-2, soil conditioner consisted of the following ingredients by weight: 45% lime, 45% zeolite, 5% superphosphate, and 5% biomass char, the remainder being identical to example 1.

The comparative example 2 and the soil conditioner comprise the following components in percentage by weight: 42% lime, 52% zeolite, 5% superphosphate, and 1% biomass char, the remainder being identical to example 1.

Comparative example 3-1, superphosphate was changed to dibasic calcium phosphate; the content is not changed; the rest is equivalent to embodiment 1.

Comparative example 3-2, the perphosphate was changed to monopotassium phosphate; the content is not changed; the rest is equivalent to embodiment 1.

Comparative experiment: all the comparative examples are detected according to the method of the experiment 2, and the addition amount of the soil conditioner is 0.5 percent; the results at harvest of rice are shown in table 3 below.

Table 3 biomass and yield of each comparative rice

Finally, it is also noted that the above-mentioned lists merely illustrate a few specific embodiments of the invention. It is obvious that the invention is not limited to the above embodiments, but that many variations are possible. All modifications which can be derived or suggested by a person skilled in the art from the disclosure of the present invention are to be considered within the scope of the invention.

Claims

1. The soil conditioner for restoring Cd pollution of soil is characterized by comprising the following components in parts by weight: 47% lime, 47% zeolite, 5% superphosphate, and 1% biomass char;

the superphosphate is granular superphosphate, the lime is powdered calcium oxide, the zeolite is powdered artificial zeolite, and the biomass charcoal is prepared by heating bamboo in an oxygen-free closed container to 600 +/-50 ℃ for heat treatment for 2 hours;

the soil conditioner is used for restoring Cd pollution of soil.

2. The method of applying a soil amendment for remediating Cd-contaminated soil as recited in claim 1, further comprising: uniformly applied into soil, and the addition amount is 1.25 kg.m^-2～5kg·m^-2。

3. The application method of a soil conditioner for remediating Cd-contaminated soil as set forth in claim 2, wherein the application method comprises the steps of: the addition amount is 1.25kg · m^-2、2.5kg·m^-2。