CN115812545A - Methods to reduce nickel accumulation and nickel bioavailability in rice - Google Patents

Abstract

The invention provides a method for reducing rice nickel accumulation and nickel bioavailability, and reduces rice nickel accumulation and nickel bioavailability by spraying sodium iron ethylenediamine tetraacetate on leaves. The invention adopts bio-augmentation measures to increase the iron content in rice grains and simultaneously reduce nickel accumulation and nickel bioavailability in rice grains. Different from previous complex and time-consuming methods such as soil remediation to reduce the accumulation of nickel in rice, this invention uses a simple method of spraying sodium iron edetate on the leaves to simultaneously reduce the nickel content and nickel bioavailability of rice, and improve the rice nutritional quality of iron. The invention will establish new measures for the prevention and control of health risks of nickel exposure, and make new contributions to my country's food safety assurance capabilities.

Description

Methods to reduce nickel accumulation and nickel bioavailability in rice

technical field

The invention belongs to the technical field of heavy metal prevention and control, and in particular relates to a method for reducing rice nickel accumulation and nickel bioavailability.

Background technique

The most widely studied heavy metals in the environmental field, such as arsenic, lead, cadmium, mercury, etc., mostly come from man-made pollution behaviors such as coal burning, industrial "three wastes" emissions, traffic exhaust, pesticides and fertilizers. However, soil nickel pollution mainly comes from the high background value of soil and the weathering of background parent material. Weathered basalt soils widely exist in eastern China, where the background value of nickel is 24.6–422 mg kg ^-1 , which is 3.68 times the average background value of nickel in soils worldwide. Excessive nickel intake can lead to skin inflammation, trachoma, chronic pharyngitis, bronchitis, and even cancer. Nickel in the soil is easily enriched in rice grains and ingested by people along with rice consumption, resulting in potential adverse effects. The intake of nickel through rice is considered to be the main route of nickel exposure in the population. Therefore, how to conveniently, reasonably, effectively and safely control the health risks of residents in areas with high background value of nickel in soil through eating rice has become an urgent issue to be solved. At present, the most extensive technology is to reduce nickel accumulation in rice by taking measures, such as remediation of contaminated soil or application of passivation agents, screening of rice varieties with low nickel accumulation, etc. time cost.

Considering the bioavailability of rice after ingestion into the human body, that is, only the nickel element with bioavailability can be absorbed by the digestive tract and enter the blood circulation, controlling the bioavailability of rice nickel is undoubtedly an effective control measure for human nickel exposure . Early studies have proved that nickel and iron have relatively similar chemical properties and environmental behaviors, and the iron absorption channel in the human digestive tract is also the main way for nickel to be absorbed. On the other hand, the absorption pathways of nickel and iron in plants are also considered to be common, and the iron content in plants can be enhanced by foliar spraying of iron, which can promote the competition of iron and nickel in the process of transport in plants.

Contents of the invention

At present, the prevention and control of rice nickel human health hazard risk is mostly done by reducing soil nickel activity and passivating nickel elements to indirectly reduce the absorption and accumulation of nickel by rice. From the perspective of the bioavailability of nickel in the human gastrointestinal tract after ingestion, corresponding bioavailability control measures are developed to reduce the health risks of human nickel exposure.

The purpose of the present invention is to increase the iron content of rice by developing rice iron bioenhancement measures, and simultaneously reduce rice nickel accumulation and nickel bioavailability, and finally achieve the purpose of regulating the health hazards of rice nickel.

The invention adopts bio-augmentation measures to increase the iron content in rice grains and simultaneously reduce nickel accumulation and nickel bioavailability in rice grains. Different from previous complex and time-consuming methods such as soil remediation to reduce the accumulation of nickel in rice, this invention uses a simple method of spraying sodium iron edetate on the leaves to simultaneously reduce the nickel content and nickel bioavailability of rice, and improve the rice nutritional quality of iron. The invention will establish new measures for the prevention and control of health risks of nickel exposure, and make new contributions to my country's food safety assurance capabilities.

The technical solution is:

The method for reducing nickel accumulation and nickel bioavailability in rice is to reduce nickel accumulation and nickel bioavailability in rice by foliar spraying of sodium iron ethylenediamine tetraacetate.

Specifically include the following steps:

(1) Collection and preparation of nickel-contaminated soil

Collect polluted soil from nickel-contaminated farmland in high-nickel background areas. After natural air-drying, remove debris, pass through a 2mm sieve, mix evenly, and put it into plastic pots, about 35kg of dry soil per pot;

(2) Planting rice in the greenhouse and spraying sodium iron edetate on the leaves

Select the hybrid indica rice variety that is commonly planted in East my country, spread the rice seedling raising substrate on the rice seedling tray, evenly sprinkle the seeds and cover with a thin layer of substrate soil, and finally spray water to ensure that the entire substrate is fully moist; Spray water frequently during the seedling raising period to ensure that the rice seedlings are sufficiently hydrated until the seedlings are transplanted, and the seedling period does not exceed 1 month;

Fully flood the paddy soil in the plastic pot one week before transplanting the seedlings, and cover the soil surface with water up to 1-2cm; when transplanting the seedlings, transplant the rice seedlings and their roots into the plastic pots. About 18 seedlings were transplanted into the soil; after transplanting, the rice growth and development were managed according to the principle of "turning green in deep water, tillering in shallow water, enough seedlings to dry the field, and alternating dry and wet in the later stage"; set up a control group and a foliar spraying iron fertilizer treatment group , after the paddy rice enters the filling period, the foliar spraying group is sprayed with sodium ferric edetate, and the frequency of spraying is 2L of 1g L ^-1 sodium ferric edetate solution twice a week, The 2L solution was evenly sprayed on three pots of rice leaves each time;

(3) Rice harvesting and processing

After the rice enters the wax ripening stage, it is harvested, and the rice ear part, the aboveground part of the stalk leaf and the root system are cut off for the following processing and analysis; the rice ear is brought back to the laboratory after being harvested and dried naturally for a week. Ear weight and ear number yield data need to be calculated before being peeled off from the ears of rice, and 1,000-grain weight yield data must be calculated for the stripped rice grains, and then husked with a rice grinder to form polished rice; some polished rice samples are ground into powder for elemental analysis ; The stems above the ground are rinsed with tap water and pure water, freeze-dried, and ground for elemental analysis; the root system is fully washed with tap water and pure water, freeze-dried, and ground for elemental analysis;

(4) Analysis of nickel and iron elements in rice grains and plant parts

(5) Determination of human bioavailability of nickel in rice

(6) Assessment of human nickel exposure doses caused by rice intake

Considering the content and bioavailability of nickel in rice comprehensively, and based on the amount of rice ingested by adults or children per week, calculate and compare the weekly nickel exposure dose caused by rice intake in the control group and the foliar iron-sprayed treatment group, to establish the possible Iron biofortification measures to reduce the human bioavailability of rice nickel and the dose of nickel intake in humans.

Concretely, the method for analyzing nickel and iron elements in rice grains and plant parts in step (4) is as follows:

Quantitatively weigh 0.5g of polished rice, paddy shoot or root sample powder, add 10mL of _HNO3 aqueous solution, the _HNO3 in the _HNO3 aqueous solution is mixed with water according to the volume ratio of 1:1;

Put it into a graphite furnace digestion apparatus and digest it at 105°C for 6 hours;

After cooling, add 2mL H ₂ O ₂ , put it into an ink furnace digestion apparatus, and continue to digest at 105°C until the residual volume of the digestion solution is less than 1mL;

Use pure water to dilute the digestion solution to 50mL; then use inductively coupled plasma mass spectrometer and inductively coupled plasma atomic emission spectrometer to measure the content of nickel and iron in the digestion solution, and finally calculate the nickel and iron in polished rice and rice plant parts element content;

Compared with the control group and the foliar iron spraying treatment group, the effects of foliar iron spraying on the accumulation of nickel and iron in grains, as well as the accumulation of nickel and iron in the aerial parts and roots of rice were analyzed.

Due to the variety of iron fertilizers used in foliar spraying, it is possible to achieve the same iron supplementation and reduce rice nickel by spraying other iron fertilizers such as ferrous sulfate, ferric citrate, amino acid chelated iron, and nano-iron Accumulation and nickel bioavailability purposes.

The applicant's research shows that by directly adding iron salts such as iron sodium ethylenediaminetetraacetate, ferric citrate, ferrous sulfate, ferrous gluconate and other iron supplements to the rice diet, it is also possible to reduce the bioavailability of rice nickel. Purpose.

Different from the previous technical means for reducing nickel accumulation in rice, the present invention can not only effectively reduce nickel accumulation in rice through simple foliar spraying measures of iron fertilizer, but also effectively reduce nickel intake in rice from the perspective of rice nickel bioavailability. regulation. Iron bioaugmentation measures that can simultaneously reduce rice nickel accumulation and nickel bioavailability have been developed to achieve the purpose of reducing the health hazards of nickel exposure in the population.

Description of drawings

Fig. 1 is a flowchart of an embodiment.

Detailed ways

The specific technical solutions of the present invention are described in conjunction with the examples.

As shown in Fig. 1, nickel accumulation and nickel bioavailability in rice were reduced by foliar spraying of NaFeEDTA.

(1) Collection and preparation of nickel-contaminated soil

Collect polluted soil from nickel-contaminated farmland in nickel-high background areas, after natural air-drying, remove debris, pass through a 2mm sieve, mix evenly, and put it into plastic pots (60cm long, 30cm wide, 20cm deep), each pot About 35kg dry soil.

(2) Planting rice in the greenhouse and spraying sodium iron edetate on the leaves

Choose the hybrid indica rice variety that is commonly planted in East my country, spread the rice seedling substrate on the rice seedling tray, evenly sprinkle the seeds and cover with a thin layer of substrate soil, and finally spray water to ensure that the entire substrate is fully moist. Spray and water frequently during the seedling raising period to ensure that the rice seedlings have sufficient water until the seedlings are transplanted, and the seedling period does not exceed 1 month.

The paddy soil in the plastic pot needs to be fully flooded with water one week before transplanting the seedlings, and it is advisable to cover the soil surface with 1-2cm of water. When transplanting the seedlings, the rice seedlings and their root systems were transplanted into plastic pots. During the process, the root system of the rice seedlings was ensured to be relatively intact. About 18 seedlings were transplanted into each pot. After transplanting the seedlings, manage the growth and development of rice according to the principle of "turning green in deep water, tillering in shallow water, enough seedlings to dry the field, and alternating dry and wet in the later stage". Set up the control group and the foliar spraying iron fertilizer treatment group. After the rice enters the grain filling stage, the foliar spraying group is foliarly sprayed with 2 L of 1 g sodium ferric edetate twice a week. L ^-1 sodium ferric ethylenediamine tetraacetate solution (iron element content is about 150 mg L ^-1 ), 2 L of solution was evenly sprayed on the leaves of three pots of rice each time.

(3) Rice harvesting and processing

After the rice entered the wax ripening stage, it was harvested, and the rice panicle part, the above-ground part of the stem, leaf and root system were cut for the following processing and analysis. After the rice ears are harvested, they are brought back to the laboratory and dried naturally for a week. Before the grains are peeled off from the rice ears, the yield data such as ear weight and number of ears need to be calculated, and the peeled rice grains need to be calculated. It can be husked by a rice grinder to form polished rice. Some polished rice samples were ground into powder for elemental analysis. The stems above the ground were rinsed with tap water and pure water, freeze-dried, and then pulverized for elemental analysis. After the root system is thoroughly washed with tap water and pure water, it is freeze-dried and ground into powder for elemental analysis.

(4) Analysis of nickel and iron elements in rice grains and plant parts

Quantitatively weigh polished rice, paddy shoot or root sample powder (0.5g), add 10mL 1:1 (V:V) HNO ₃ , put it into a graphite furnace digestion apparatus, and digest it at 105°C for 6h; after cooling, Add 2mL H ₂ O ₂ , put it into an ink furnace digestion apparatus, and continue to digest at 105°C until the residual volume of the digestion solution is <1mL; use pure water to make the digestion solution volume up to 50mL; then use inductively coupled plasma mass spectrometry Inductively coupled plasma mass spectrometry (ICP-MS) and inductively coupled plasma optical emission spectrometer (ICP-OES) were used to measure the contents of nickel and iron in the digestion solution, and finally calculate the contents of polished rice and rice plants. Nickel and iron content (mg kg ^-1 dry weight). Compared with the control group and the foliar iron spraying treatment group, the effects of foliar iron spraying on the accumulation of nickel and iron in grains, as well as the accumulation of nickel and iron in the aerial parts and roots of rice were analyzed.

(5) Determination of human bioavailability of nickel in rice

In vivo mice experiments were carried out to determine the relative bioavailability (RBA) of nickel ingested in milled rice relative to the ingestion of pure nickel sulfate, and thus reflect the human bioavailability of nickel in rice. The following is a brief description of the experimental process: First, weigh the harvested polished rice samples, put them into a household electric cooker, and add appropriate pure water to cook them. After the rice was cooked, it was poured out from the pot, extruded to make rice balls and then freeze-dried; in addition, quantitative mixing of aqueous solution containing nickel sulfate and blank commercially available rice (nickel content less than 0.04mg kg ^-1 ) was also cooked Preparation of rice ball feed containing nickel sulfate. After the preparation, the rice ball feed was quantitatively exposed to the mice for a total of 7 days, and the mice were kept in metabolic cages, and could freely eat the rice ball feed and pure water. After the mice were exposed for 7 days, the nickel-containing rice ball feed was replaced with a blank rice feed on the 8th day, and the exposure period ended after continuing to feed for one day. The urine excreted by the mice during the 8-day exposure period was collected in a clean centrifuge tube, and the volume was fixed to the same volume, and passed through a 0.45mm filter membrane after high-speed centrifugation. Urine samples were diluted by appropriate times to determine the nickel content by ICP-MS. The total nickel intake was calculated by calculating the consumption of rice balls per mouse (excluding the blank rice on the eighth day) and combining the nickel concentration in the rice. Calculate the mouse nickel excretion factor, which is the ratio of the total nickel excreted in urine to the total nickel intake. The relative bioavailability of nickel for the corresponding rice sample was obtained by comparing the excretion factor of mice fed nickel rice samples with that of mice ingested nickel sulfate. Compared with the control group and the foliar iron spraying group, the effect of foliar spraying of sodium ferric edetate on the relative bioavailability of nickel in rice was analyzed.

(6) Assessment of human nickel exposure doses caused by rice intake

Considering the content and bioavailability of nickel in rice comprehensively, and based on the amount of rice ingested by adults or children per week, calculate and compare the weekly nickel exposure dose caused by rice intake in the control group and the foliar iron-sprayed treatment group, to establish the possible Iron bioenhancement measures to reduce the human bioavailability of rice nickel and the human nickel intake dose are used to guide the safe production of rice in areas with high nickel background, and provide guidance for the protection of human health.

From 2020 to 2021, our research group used the method of the present invention to conduct two-season repeated greenhouse potting experiments using the nickel-high background soil in Xuyi, Jiangsu Province as an example. In the process of planting rice, a control group and a treatment group of sodium ferric edetate sprayed on the leaves were set up. Rice samples were harvested after the rice matured and ground and hulled into polished rice. Based on the results of two years, the foliar spraying of iron fertilizer reduced the nickel content of polished rice from 3.56-3.71mg kg ^-1 to 1.05-1.10mg kg ^-1 , and iron The element content rises from about 10 mg kg ^-1 to 30 mg kg ^-1 . Foliar fertilization of iron fertilizers strongly reduced Ni accumulation in rice grains and improved the iron nutritional quality of rice. By exposing the harvested control rice and iron-sprayed rice to mice, the bioavailability of rice nickel was measured. It was found that foliar spraying reduced the bioavailability of rice nickel from 70.4-77.8% to 42.4-53.7%. The increase of iron in rice effectively reduced the bioavailability of nickel in rice.

The present invention starts from the growth and development process of rice and the absorption process after the human body ingests nickel rice, provides a two-pronged favorable measure for the prevention and control of rice nickel human health hazards, and further explores nutritional element bioenhancement measures to reduce human nickel in the future. Exposure provides sufficient and favorable scientific basis, and provides new ideas and strategies for reducing the health hazards of nickel.

Claims (3)

1. The method for reducing rice nickel accumulation and nickel bioavailability is characterized in that, reducing rice nickel accumulation and nickel bioavailability by foliar spraying of sodium ferric ethylenediamine tetraacetate. 2. the method for reducing rice nickel accumulation and nickel bioavailability according to claim 1, is characterized in that, specifically comprises the following steps: (1) Collection and preparation of nickel-contaminated soil Collect polluted soil from nickel-contaminated farmland in nickel-high background areas. After natural air-drying, remove debris, pass through a 2mm sieve, mix evenly, and put it into plastic pots, 35kg of dry soil per pot; (2) Planting rice in the greenhouse and spraying sodium iron edetate on the leaves Select the hybrid indica rice variety that is commonly planted in East my country, spread the rice seedling raising substrate on the rice seedling tray, evenly sprinkle the seeds and cover with a thin layer of substrate soil, and finally spray water to ensure that the entire substrate is fully moist; Spray water frequently during the seedling raising period to ensure that the rice seedlings are sufficiently hydrated until the seedlings are transplanted, and the seedling period does not exceed 1 month; Fully flood the paddy soil in the plastic pot one week before transplanting the seedlings, and cover the soil surface with water up to 1-2cm; when transplanting the seedlings, transplant the rice seedlings and their roots into the plastic pots. About 18 seedlings were transplanted into the soil; after transplanting, the rice growth and development were managed according to the principle of "turning green in deep water, tillering in shallow water, enough seedlings to dry the field, and alternating dry and wet in the later stage"; set up a control group and a foliar spraying iron fertilizer treatment group , after the paddy rice enters the filling period, the foliar spraying group is sprayed with sodium ferric edetate, and the frequency of spraying is 2L of 1g L ^-1 sodium ferric edetate solution twice a week, The 2L solution was evenly sprayed on three pots of rice leaves each time; (3) Rice harvesting and processing After the rice enters the wax ripening stage, it is harvested, and the rice ear part, the aboveground part of the stalk leaf and the root system are cut off for the following processing and analysis; the rice ear is brought back to the laboratory after harvest and dried naturally for a week. Ear weight and ear number yield data need to be calculated before being peeled off from the ears of rice, and 1,000-grain weight yield data must be calculated for the peeled rice grains, and then the rice mills are used for husking to form polished rice; some polished rice samples are ground into powder for elemental analysis ; The stems above the ground are rinsed with tap water and pure water, freeze-dried and ground for elemental analysis; the root system is fully washed with tap water and pure water, freeze-dried and ground for elemental analysis; (4) Analysis of nickel and iron elements in rice grains and plant parts (5) Determination of human bioavailability of nickel in rice (6) Assessment of human nickel exposure doses caused by rice intake Considering the content and bioavailability of nickel in rice comprehensively, and based on the amount of rice ingested by adults or children per week, calculate and compare the weekly nickel exposure dose caused by rice intake in the control group and the foliar iron-sprayed treatment group, to establish the possible Iron biofortification measures to reduce the human bioavailability of rice nickel and the dose of nickel intake in humans. 3. the method for reducing rice nickel accumulation and nickel bioavailability according to claim 2, is characterized in that, step (4) rice grain and plant part nickel-iron element analysis method is: Quantitatively weigh 0.5g of polished rice, paddy shoot or root sample powder, add 10mL of _HNO3 aqueous solution, the _HNO3 in the _HNO3 aqueous solution is mixed with water according to the volume ratio of 1:1; Put it into a graphite furnace digestion apparatus and digest it at 105°C for 6 hours; After cooling, add 2mL H ₂ O ₂ , put it into an ink furnace digestion apparatus, and continue to digest at 105°C until the residual volume of the digestion solution is less than 1mL; Use pure water to dilute the digestion solution to 50mL; then use inductively coupled plasma mass spectrometer and inductively coupled plasma atomic emission spectrometer to measure the content of nickel and iron in the digestion solution, and finally calculate the nickel and iron in polished rice and rice plant parts element content; Compared with the control group and the foliar iron spraying treatment group, the effects of foliar iron spraying on the accumulation of nickel and iron in grains, as well as the accumulation of nickel and iron in the aerial parts and roots of rice were analyzed.

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