CN111133966A

CN111133966A - Method for reducing arsenic concentration of rice in soil with severe arsenic pollution by applying selenium

Info

Publication number: CN111133966A
Application number: CN201911257082.7A
Authority: CN
Inventors: 刘建国; 刘远康; 丁淼
Original assignee: Changzhou University
Current assignee: Changzhou University
Priority date: 2019-12-10
Filing date: 2019-12-10
Publication date: 2020-05-12

Abstract

The invention relates to a method for reducing the concentration of arsenic in rice in soil heavily polluted by arsenic by applying selenium, which is characterized by comprising the following steps: in arsenic contaminated soil (the concentration of arsenic in the soil is 100mg/kg, which is more than 3 times of the limit value of arsenic content in soil of producing area of edible agricultural products in China, and belongs to severe contamination), the total selenium application amount is 90g/hm²The total selenium amount of 1/2 is applied in two times, namely 10 days after the rice is planted and 5 days before the ear is taken. Before selenium application, thin layer water (about 3cm) is irrigated in the rice field, and the selenium fertilizer is dissolved in the water to be sprayed, wherein the water consumption per hectare is about 450kg each time. Compared with the common method without selenium in the actual production of rice, the implementation effect of the method has the advantages that the arsenic content of rice is greatly reduced (the content of indica rice is reduced by 54.0 percent, the content of japonica rice is reduced by 52.00 percent), and the yield of rice is not reduced. In areas with severe arsenic pollution of soil, the application of the technical scheme can greatly reduce the threat of arsenic pollution of rice to human health.

Description

Method for reducing arsenic concentration of rice in soil with severe arsenic pollution by applying selenium

Technical Field

The invention relates to a method for reducing the concentration of arsenic in rice in soil heavily polluted by arsenic by applying selenium, belonging to the technology of prevention and treatment of heavy metal pollution of crops.

Background

In recent thirty years, due to the rapid development of mining, smelting and other industries and the use of arsenic-containing pesticides, fertilizers, biological growth regulators and the like in large quantities, farmland soil in many countries and regions in the world is polluted by arsenic. Arsenic accumulated in the paddy field soil can be absorbed by the root system of the rice and then transferred to the edible part of human, namely the rice, and then enters the human body through a food chain, thus seriously threatening the health of the human body. In addition, China is also a big energy country, the energy structure is mainly coal, and coal is the most serious energy source for pollution. Some coals can contain up to 35000mg/kg arsenic, and the amount of arsenic discharged by burning coal is about 2500 tons every year, and the arsenic is returned to land and water areas in the form of dry and wet sedimentation of the atmosphere, and finally causes arsenic pollution to soil.

Arsenic has strong toxicity to human bodies, and is classified as a carcinogen to human beings by various authorities such as the World Health Organization (WHO), the international agency for research on cancer (IARC), the United States Environmental Protection Agency (USEPA), and the like. Research shows that exposure to arsenic-contaminated environment can cause arsenic poisoning, damage to functions of various organs and systems of a human body, and cause diseases, such as hypertension, cardiovascular and cerebrovascular diseases, neuropathy, diabetes, skin pigment metabolism disorder, skin keratinization and the like, which are clinically manifested, and finally can develop into skin cancer, bladder cancer, canceration of various organs such as kidney, liver and the like.

Rice is the most important food crop in China, and most people take rice as staple food, especially in dense Yangtze river basin and south China. According to research, arsenic can enter human bodies through rice straws and rice through a food chain, and brings direct or indirect harm to human health. Arsenic in rice grains is a main source of human arsenic in a rice staple food area, and the contribution of the arsenic to human arsenic exposure is larger than that of drinking water. Therefore, the prevention and control of arsenic pollution of rice fields and rice are very important for guaranteeing the health of people in China.

In the arsenic-polluted areas of the rice fields, the arsenic content in rice grains is influenced not only by the soil pollution condition and the rice variety, but also by the cultivation technology. During the growth of rice, the agricultural measures such as fertilization and water management can change the physical and chemical conditions of soil and the growth condition of rice, so that the existing state of arsenic in the soil and the effectiveness of the arsenic on plants can be changed, and the absorption and distribution of the arsenic by the rice are influenced. Different amounts and methods of applying selenium to rice fields have different effects on the absorption and migration of arsenic in rice plants. However, there is still a very lack of research on the influence of the application level and application method of selenium fertilizer on the arsenic content of rice.

On the basis of years of research of an applicant, the invention discloses a method for reducing the arsenic concentration of rice in soil heavily polluted by arsenic by applying selenium, which can greatly reduce the arsenic content of the rice and can not reduce the rice yield.

Disclosure of Invention

The technical problem to be solved by the invention is as follows: the method for reducing the arsenic concentration of the rice in the soil with severe arsenic pollution by applying selenium can greatly reduce the arsenic content of the rice in the soil with arsenic pollution, and the rice yield cannot be reduced.

The technical scheme adopted by the invention for solving the technical problems is as follows: a method for reducing the arsenic concentration of rice in soil heavily polluted by arsenic by applying selenium is characterized in that: in arsenic contaminated soil (the concentration of arsenic in the soil is 100mg/kg, which is more than 3 times of the limit value of arsenic content in soil of producing area of edible agricultural products in China, and belongs to severe contamination), the total selenium application amount is 90g/hm²The total selenium amount of 1/2 is applied in two times, namely 10 days after the rice is planted and 5 days before the ear is taken. Before selenium application, thin-layer water (about 3cm) is irrigated in the rice field, the selenium fertilizer is dissolved in the water and sprayed, the water consumption per hectare is about 450kg each time, the selenium fertilizer is uniformly sprayed in the rice field after being dissolved and uniformly mixed, the water is irrigated after the water layer naturally falls to the dry state, and water is not drained before the water layer falls to the dry state.

The invention has the beneficial effects that: after the method is implemented in areas with severe arsenic pollution in the rice field, the arsenic content of the rice can be greatly reduced, and the yield of the rice cannot be reduced. Compared with the common rice production without selenium application, the arsenic content of the rice is greatly reduced (the content of indica rice is reduced by 54.0 percent, the content of japonica rice is reduced by 52.00 percent) (see table 1), and the rice yield is not reduced (see table 2). In areas with severe arsenic pollution of soil (the content of the arsenic in the soil is 100mg/kg and is more than 3 times of the limit value of the arsenic content in soil in producing areas of edible agricultural products in China), the arsenic content of rice can be controlled below the limit value of the national sanitary standard (0.2mg/kg, GB2762-2012) through the implementation of the technical scheme of the application patent, and the threat of the arsenic pollution of rice to the human health can be greatly reduced.

Detailed Description

Example 1: a method for reducing arsenic concentration of rice in soil heavily polluted by arsenic by applying selenium comprises applying selenium in a total amount of 90g/hm in the whole rice production period²The total selenium amount of 1/2 is applied in two times, namely 10 days after the rice is planted and 5 days before the ear is taken. Before selenium application, thin layer water (about 3cm) is irrigated in rice field, and selenium fertilizer is dissolved in waterThe selenium fertilizer is uniformly sprayed into the rice field after being dissolved and uniformly mixed, the water layer is naturally dried and then irrigated, and water is not drained before the water layer is dried.

The method further proves that the arsenic content of the rice in the soil with severe arsenic pollution can be greatly reduced, and the yield of the rice is not reduced. The data in the table are obtained under the conditions that the arsenic content in soil is 100mg/kg and reaches more than 3 times of the limit value of the arsenic content in soil of producing areas of edible agricultural products in China (belonging to severe pollution), and other fertilizer and water management measures are carried out according to the rice production routine.

TABLE 1 comparison of arsenic content (unit: mg/kg) of rice at different selenium application levels and under the selenium application method

One-time application: the selenium fertilizer is applied once 10 days after the rice is transplanted.

The application is divided into two times: 1/2 of the total selenium application amount is respectively applied 10 days after the rice is planted and 5 days before the ear emergence.

The selenium-enriched fertilizer is applied for three times, wherein 1/3 of the total selenium application amount is respectively applied 10 days after the rice is planted, 5 days before the ear is taken and 5 days after the ear is taken.

TABLE 2 comparison of Rice yields at different selenium application levels and methods (unit: kg/hm)²)

From the two aspects of selenium application level and selenium application method, it can be seen from the analysis of tables 1 and 2 that:

(1) from selenium-application horizontal analysis

Under different selenium application levels, the arsenic content of rice and the rice yield are changed differently. In terms of arsenic content of rice, the sequence at different selenium application levels is: high level selenium application ≈ medium level selenium application < low level selenium application < no selenium application. Under the conditions of medium-level and high-level selenium application, the arsenic content of indica rice and japonica rice is greatly reduced, but no obvious difference exists between the medium-level and high-level selenium application. In terms of rice yield, the sequence at different selenium levels is: high selenium application > medium selenium application > low selenium application > no selenium application, but the difference between the selenium application levels is small (typically less than 2%).

(2) Analysis from selenium application method

In the different selenium application methods, the sequence of the arsenic content of the rice is as follows: the selenium is applied in three times, the selenium is applied in two times, the selenium is applied in one time, but the difference between the selenium application in three times and the selenium application in two times is very small. The sequence of rice yield is: selenium application is divided into three times and two times, and selenium application is divided into one time and one time, but the difference between different selenium application methods is not large (generally less than 2%).

The influence of selenium application level and selenium application method on arsenic content of rice and rice yield is synthesized, and medium-level selenium application (90 g/hm) is selected in consideration of selenium application cost²) The selenium applying method of applying the selenium in two times (1/2 of total selenium applying amount is applied respectively 10 days after rice seedling planting and 5 days before ear emergence) can greatly reduce the arsenic content of rice, control the arsenic content of the rice below the limit value of the national sanitary standard (0.2mg/kg, GB2762-2012), and can also ensure that the yield of the rice cannot be reduced.

Claims

1. A method for reducing the arsenic concentration of rice in soil heavily polluted by arsenic by applying selenium is characterized in that: in arsenic contaminated soil (the concentration of arsenic in the soil is 100mg/kg, which is more than 3 times of the limit value of arsenic content in soil of producing area of edible agricultural products in China, and belongs to severe contamination), the total selenium application amount is 90g/hm²(silicon application at medium level).

2. The method for reducing the arsenic concentration of rice in heavily arsenic-contaminated soil by selenium application as claimed in claim 1, wherein: the application is divided into two times, namely 1/2 of the total selenium application amount is applied respectively 10 days after the rice is planted and 5 days before the ear is taken, and the selenium fertilizer is dissolved in water and sprayed.