Abstract: The present disclosure discloses a method for targeted regulation of soil microbes to synchronize heavy metal/metalloid transformation and greenhouse gas emission reduction and use. The present disclosure discovers that by compounding methionine with an organic acid salt, the obtained formulation can significantly increase the ability of the soil microbes to promote arsenic methylation in a targeted mode, and meanwhile, and the methane production is effectively reduced in the presence of the methionine. In the present disclosure, the methionine/organic acid salt formulation is further loaded into a modified biochar material of a porous structure, so as to achieve the effect of slow release. The method of the present disclosure may effectively reduce absorption of inorganic arsenic by rice, achieve a significant reduction in the proportion of inorganic arsenic in the total arsenic in the rice and inhibit methane emission of the soils and reduce methane emission at the same time.

Abstract: The present disclosure discloses a method for targeted regulation of soil microbes to synchronize heavy metal/metalloid transformation and greenhouse gas emission reduction and use. The present disclosure discovers that by compounding methionine with an organic acid salt, the obtained formulation can significantly increase the ability of the soil microbes to promote arsenic methylation in a targeted mode, and meanwhile, and the methane production is effectively reduced in the presence of the methionine. In the present disclosure, the methionine/organic acid salt formulation is further loaded into a modified biochar material of a porous structure, so as to achieve the effect of slow release. The method of the present disclosure may effectively reduce absorption of inorganic arsenic by rice, achieve a significant reduction in the proportion of inorganic arsenic in the total arsenic in the rice and inhibit methane emission of the soils and reduce methane emission at the same time.

Abstract: An iron-carbon composite material and a preparation method thereof are disclosed. The iron-carbon composite material includes a three-layer core-shell structure, which successively includes a porous graphite carbon outer layer, an iron carbide intermediate layer and a nano zero-valent iron core from outside to inside. The present invention wraps nano zero-valent iron in porous graphite carbon and iron carbide, which can prevent the oxidation of nano zero-valent iron, while iron carbide effectively improves the ability to fix arsenic, realizing high efficiency and long-term use of nano zero-valent iron. Iron carbide may effectively adsorb and fix arsenic, and especially efficiently oxidize As(III) to relatively low-toxic As(V).

Abstract: An iron-carbon composite material and a preparation method thereof are disclosed. The iron-carbon composite material includes a three-layer core-shell structure, which successively includes a porous graphite carbon outer layer, an iron carbide intermediate layer and a nano zero-valent iron core from outside to inside. The present invention wraps nano zero-valent iron in porous graphite carbon and iron carbide, which can prevent the oxidation of nano zero-valent iron, while iron carbide effectively improves the ability to fix arsenic, realizing high efficiency and long-term use of nano zero-valent iron. Iron carbide may effectively adsorb and fix arsenic, and especially efficiently oxidize As(III) to relatively low-toxic As(V).

Abstract: An on-site heavy metal contaminated soil treatment apparatus, comprising a sampling system, a molding system, a heat processing system and a tail gas processing system disposed in sequence. The sampling system includes a bucket elevator and a planetary stirring device which are connected in sequence and are disposed on a mobile platform of the sampling system. The apparatus is easy to move and assemble, has a small floor area, and can be built on a target contaminated site, reducing transportation costs and the risk of secondary contamination. The entire process performed by the apparatus proceeds automatically, reducing labor costs. The planetary stirring sampling method and automatic brick blank extrusion molding process of the apparatus are applicable to various types of heavy metal contaminated soil providing high processing efficiency and good molding effect. Combined microwave heating and high-temperature steam heating provide rapid heating, small thermal inertia, and easy temperature control.

Abstract: An on-site heavy metal contaminated soil treatment apparatus, comprising a sampling system, a molding system, a heat processing system and a tail gas processing system disposed in sequence. The sampling system includes a bucket elevator and a planetary stirring device which are connected in sequence and are disposed on a mobile platform of the sampling system. The apparatus is easy to move and assemble, has a small floor area, and can be built on a target contaminated site, reducing transportation costs and the risk of secondary contamination. The entire process performed by the apparatus proceeds automatically, reducing labor costs. The planetary stirring sampling method and automatic brick blank extrusion molding process of the apparatus are applicable to various types of heavy metal contaminated soil providing high processing efficiency and good molding effect. Combined microwave heating and high-temperature steam heating provide rapid heating, small thermal inertia, and easy temperature control.

Abstract: The present invention discloses a method for safe production of rice on soil mildly and moderately polluted by heavy metals. The method includes applying a passivator before transplanting rice seedlings to reduce activity of heavy metals in soil, and then spraying a foliar barrier from the peak tillering stage to the booting stage of rice and at the filling stage of rice; the passivator includes bentonite, gypsum powder, lime, a biochar, an iron-based biochar, a slow-release iron-based biochar, an iron-sulfur-silicon composite biochar, a heavy metal cadmium passivator and a cadmium-arsenic synchronous passivator for activating sulfur reducing bacteria in paddy soil; and the foliar barrier includes an acid silica sol, a selenium-silicon composite sol, a cerium composite silica sol, a ferrous modified selenium sol. The method can also include applying a nitrate nitrogen fertilizer at the seedling stage of rice, and/or applying a phosphorus potassium fertilizer at the tillering stage of rice.

Abstract: A ferrous modified selenium sol for inhibiting accumulation of cadmium and arsenic in rice and the preparation method and application thereof are disclosed. The method includes: dissolving an iron-containing compound and a selenium-containing compound into water; adding a reductant to the solution, and stirring until no more precipitation is generated, then adding carbonate, continuing to stir until no more precipitation is generated, and then filtering, taking the precipitation, and washing to obtain the precipitation of the selenium element and ferrous carbonate; adding an emulsifier to a citric acid buffer solution to obtain an emulsified citric acid buffer solution; adding the precipitation of the selenium element and ferrous carbonate to the emulsified citric acid buffer solution to obtain a sol system; and evaporating to concentrate the sol system, and adjusting the pH to 4.5-8.5 to obtain a ferrous modified selenium sol for inhibiting the accumulation of cadmium and arsenic in rice.

Abstract: The present invention discloses a method for safe production of rice on soil mildly and moderately polluted by heavy metals. The method includes applying a passivator before transplanting rice seedlings to reduce activity of heavy metals in soil, and then spraying a foliar barrier from the peak tillering stage to the booting stage of rice and at the filling stage of rice; the passivator includes bentonite, gypsum powder, lime, a biochar, an iron-based biochar, a slow-release iron-based biochar, an iron-sulfur-silicon composite biochar, a heavy metal cadmium passivator and a cadmium-arsenic synchronous passivator for activating sulfur reducing bacteria in paddy soil; and the foliar barrier includes an acid silica sol, a selenium-silicon composite sol, a cerium composite silica sol, a ferrous modified selenium sol. The method can also include applying a nitrate nitrogen fertilizer at the seedling stage of rice, and/or applying a phosphorus potassium fertilizer at the tillering stage of rice.

Abstract: A ferrous modified selenium sol for inhibiting accumulation of cadmium and arsenic in rice and the preparation method and application thereof are disclosed. The method includes: dissolving an iron-containing compound and a selenium-containing compound into water; adding a reductant to the solution, and stirring until no more precipitation is generated, then adding carbonate, continuing to stir until no more precipitation is generated, and then filtering, taking the precipitation, and washing to obtain the precipitation of the selenium element and ferrous carbonate; adding an emulsifier to a citric acid buffer solution to obtain an emulsified citric acid buffer solution; adding the precipitation of the selenium element and ferrous carbonate to the emulsified citric acid buffer solution to obtain a sol system; and evaporating to concentrate the sol system, and adjusting the pH to 4.5-8.5 to obtain a ferrous modified selenium sol for inhibiting the accumulation of cadmium and arsenic in rice.

Abstract: The invention discloses a method for the preparation and use of a slow-release iron-based biochar soil heavy metal passivator. The slow-release iron-based biochar soil heavy metal passivator of the present invention is prepared by an one-step method, wherein iron-based biochar, kaolin and a biological starch are mixed into a core material in a specific ratio; an acidic silica sol and a chitosan solution are prepared, under the effects of an alkaline catalyst and an emulsifier, as a chitosan and silica-sol composite material as a coating, and the iron-based biochar is coated with the alkaline coating material, with the core material and the coating material being controlled at a certain volume ratio. The passivator has a wide raw material source, a simple and convenient preparation process, easy industrialized production, and can passivate the heavy metal arsenic and cadmium efficiently and inhibit the absorption and accumulation of arsenic and cadmium.

Abstract: The present invention relates to the field of environmental protection, and in particular to a leaf surface barrier for accurately controlling cadmium absorption and transport related gene expression in rice, and an application thereof. The present invention comprises: reducing a raw material, i.e., selenious acid or selenite, by using ascorbic acid to generate a nanogel, and then emulsifying the nanogel for peptization to obtain a leaf surface barrier for accurately controlling cadmium absorption and transport related gene expression in rice; and then mixing the leaf surface barrier with a silica sol to obtain a composite selenium and silica sol leaf surface barrier. The present invention also provides a leaf surface barricading method for accurately controlling cadmium absorption and transport related gene expression in rice.

Abstract: A heavy metal cadmium deactivator for activating the activity of sulfur-reducing bacteria in rice field soil, and an application thereof. The deactivator is constituted by electron shuttles alone or electron shuttles and electron donors, but cannot be constituted by electron donors alone. The mass ratio of the electron donors to the electron shuttles is (1:3)-(1:8). Also, a heavy metal cadmium deactivating method for activating the activity of microorganisms in rice field soil, such as sulfur-reducing bacteria. By applying the functional deactivator to rice field soil, the activity of microorganisms, such as sulfur-reducing bacteria, can be activated, thereby accelerating the reduction process of sulfur and iron in soil to facilitate the fixation of cadmium; cadmium adsorption and accumulation in rice is reduced to achieve secure production in fields moderately or lightly polluted by cadmium.

Abstract: A method for preparing the iron-based biochar material, the iron-based biochar material prepared there from and a method for controlling the heavy metal pollution in soil using the iron-based biochar material. For the iron-based biochar material of the present invention, by using a method of high-temperature carbonization, a biomass is used as a raw material and an iron-containing compound is add in the process of preparing biochar, wherein iron is incorporated in a specific ratio, to form the iron-based biochar material with a special structure and function.

Abstract: A method for preparing an iron silicon sulfur multi-element composite biochar soil heavy metal conditioner, including: adding silicate to agricultural wastes and roasting with air isolated to enable silicate to enter structural pores of biochar; enabling iron-containing slats to gather on kaolinite with a given proportion; enabling sulfate to gather on bentonite with a given proportion; mixing the above three materials evenly according to a given proportion; and adding diatomite and starch to the mixture, and pelleting to prepare the iron silicon sulfur multi-element composite biochar soil heavy metal conditioner. The conditioner can be widely applied in soil heavy metal pollution abatement of rice fields, and it is able to synchronously passivate composite pollutants in acid or alkaline soils to reduce the amount of pollutants absorbed by and accumulated in rice, thereby achieving safe utilization of polluted farmland.

Abstract: A heavy metal cadmium deactivator for activating the activity of sulfur-reducing bacteria in rice field soil, and an application thereof. The deactivator is constituted by electron shuttles alone or electron shuttles and electron donors, but cannot be constituted by electron donors alone. The mass ratio of the electron donors to the electron shuttles is (1:3)-(1:8). Also, a heavy metal cadmium deactivating method for activating the activity of microorganisms in rice field soil, such as sulfur-reducing bacteria. By applying the functional deactivator to rice field soil, the activity of microorganisms, such as sulfur-reducing bacteria, can be activated, thereby accelerating the reduction process of sulfur and iron in soil to facilitate the fixation of cadmium; cadmium adsorption and accumulation in rice is reduced to achieve secure production in fields moderately or lightly polluted by cadmium.

Abstract: A method for preparing an iron silicon sulfur multi-element composite biochar soil heavy metal conditioner, including: adding silicate to agricultural wastes and roasting with air isolated to enable silicate to enter structural pores of biochar; enabling iron-containing slats to gather on kaolinite with a given proportion; enabling sulfate to gather on bentonite with a given proportion; mixing the above three materials evenly according to a given proportion; and adding diatomite and starch to the mixture, and pelleting to prepare the iron silicon sulfur multi-element composite biochar soil heavy metal conditioner. The conditioner can be widely applied in soil heavy metal pollution abatement of rice fields, and it is able to synchronously passivate composite pollutants in acid or alkaline soils to reduce the amount of pollutants absorbed by and accumulated in rice, thereby achieving safe utilization of polluted farmland.

Abstract: The present invention relates to the field of environmental protection, and in particular to a leaf surface barrier for ac- curately controlling cadmium absorption and transport related gene expression in rice, and an application thereof. The present inven- tion comprises: reducing a raw material, i.e., selenious acid or selenite, by using ascorbic acid to generate a nanogel, and then emul- sifying the managed for peptization to obtain a leaf surface barrier for accurately controlling cadmium absorption and transport re- lated gene expression in rice; and then mixing the leaf surface barrier with a silica sol to obtain a composite selenium and silica sol leaf surface barrier. The present invention also provides a leaf surface barricading method for accurately controlling cadmium ab- sorption and transport related gene expression in rice.

Abstract: The invention discloses a method for the preparation and use of a slow-release iron-based biochar soil heavy metal passivator. The slow-release iron-based biochar soil heavy metal passivator of the present invention is prepared by an one-step method, wherein iron-based biochar, kaolin and a biological starch are mixed into a core material in a specific ratio; an acidic silica sol and a chitosan solution are prepared, under the effects of an alkaline catalyst and an emulsifier, as a chitosan and silica-sol composite material as a coating, and the iron-based biochar is coated with the alkaline coating material, with the core material and the coating material being controlled at a certain volume ratio. The passivator has a wide raw material source, a simple and convenient preparation process, easy industrialized production, and can passivate the heavy metal arsenic and cadmium efficiently and inhibit the absorption and accumulation of arsenic and cadmium.

Abstract: The present invention discloses a selenium-doped nano-silica sol capable of both inhibiting the absorption and accumulation of heavy metal in rice and producing a selenium-rich rice, and a preparation method thereof. The selenium-doped nano-silica sol of the present invention is prepared mainly by using a nano-silica sol as a carrier, sodium selenite and the like as a raw material, vitamin C and the like as a reducing agent, and polyvinylpyrrolidone and the like as an emulsifier, and doping and dispersing selenium in a specific ratio in a silica sol so as to form a selenium-doped nano-silica sol with a special structure and function. The selenium-doped nano-silica sol prepared according to the invention has high stability and high concentration, and is uniform and transparent, and has a silica content of up to 20% or more, a selenium content of up to 1% or more, and low impurity content.