| Since the reform and opening up in the 1980s,both in the economy and in other fields,our country has made great achievements.However,economic development is not a blow,it is like a double-edged sword on all aspects of our country to play an important role and influence.In the economic development at the same time,there have been many harmful phenomena and results,and the most obvious is the economic development of environmental costs.Especially in recent years,China’s economic development,industrialization and urbanization of the pace faster and faster,and the corresponding environmental pollution problems are increasingly prominent.On the daily life of the common environmental problems,the first to bear the brunt of a variety of pollution phenomena,such as:water pollution,air pollution,solid waste pollution,soil pollution,etc..The common problem of environmental pollution,pollution of soil heavy metals pollution due to its large,difficult to control,time-consuming and other reasons,has always been a problem for people,and has become increasingly serious trend in some regions,the difficulty of governance and governance costs,heavy metal pollution has become the pollution of the environment chronic illness.In our country,the soil heavy metal pollution typical including arsenic contaminated soil,especially in the area of planting rice in southern China,paddy soil arsenic pollution problem has become an important environmental pollution problem facing our country.As the planting area and yield of China’s largest food crops,rice is also an important way to China through the food exposure pathways of arsenic,and excessive exposure or long-term low doses of arsenic exposure may cause serious harm to human health.In order to ensure the safety of rice,corresponding measures should be taken to control the pollution of arsenic in rice.In recent years,in many control measures,biological activated carbon(Biochar)with its unique adsorption characteristics,wide source of raw materials and the influence on the migration of arsenic in soil transformation,making biochar has become a research hot spot of rice arsenic pollution control.This paper focuses on the current situation of arsenic pollution in China,the basic characteristics of biochar,the factors affecting the morphological transformation of arsenic in various parts of rice,and also prospects the future research direction and the emphasis on the waste resources And rice safety production to provide a reference.The biochar raw materials used in this study are from the common crop straw and waste in daily life,including peanut biochar-PNBC,mushroom stalk biochar-MSBC,rice straw biochar-(RSBC),sewage sludge biochar(SSBC)and soybean stalk biochar(SBBC)were investigated by pyrolysis and hydrolysis under aerobic conditions at 200 ℃-900 ℃ and other conditions.In the preparation of the experimental heavy metal arsenic contaminated soil from Chenzhou City,Hunan Province suburb of rural rice fields,rice seeds for the Yongxian 446.The basic physical and chemical properties of the biochar prepared under different temperature conditions were studied in the first stage of the experiment,which mainly included the pH(pH)of the biochar prepared by these different materials.Elemental composition,bio-fuel surface area,pore structure,conductivity,adsorption volume,and biochar adsorption pore size.The second stage of the experiment is to compare the basic physical and chemical properties of biochar after pyrolysis and hydrolysis under the conditions of cracking temperature of 200 ℃-900 ℃,and then select several kinds of biochar The effects of these biochar on the concentration of arsenic in rice contaminated with heavy metals were analyzed.The effects of different kinds of biochar on the adsorption of heavy metals in different parts of rice were compared.In the third stage of experiment,the effects of different kinds of biochar on different forms of arsenic in different soils were studied.The effects of different proportions of biochar on the concentration and morphology of heavy metals in rice were studied.The main conclusions are as follows:(1)for different raw materials and different pyrolysis temperature conditions for bio carbon preparation,although there are a lot of basic physical and chemical properties are different,but the pH value(pH value)are alkaline,which increases with the increase of pyrolysis temperature.The higher the pyrolysis temperature is,the smaller the porosity is.(2)the biological carbon prepared by different raw materials applied to the soil,rice growing in arsenic content in different parts through testing,the results show that the adsorption effect of SBBC350.SS2 and RS5 are obviously superior to other types of biochar,which can be used as modifier by heavy metal arsenic contaminated soil,to inhibition of As in soil pollution,reduce the accumulation in rice.But,some biochar applied to the soil,the concentration of growth in which the rice arsenic in part was higher than the control group,which indicates that the biological carbon does not necessarily mitigate growth in various parts of rice by the concentration of arsenic in contaminated soils,but some increase.(3)arsenic rice stem leaf and root of inorganic arsenic mainly exist,arsenite(As Ⅲ)and arsenate(As Ⅴ).Trivalent arsenic in rice stems and leaves samples under different temperature conditions for bio carbon prepared in the corresponding(As Ⅲ)concentration was significantly higher than that of arsenate(As Ⅴ),and other samples(As Ⅴ)concentration of arsenic and trivalent arsenic(As Ⅲ)concentration is not much difference between.(4)the content of organic arsenic was very low in all the stems,leaves and roots of rice,and it was mainly MMA(DMA),and almost no one could be detected.However,no organic arsenic was detected in rice root samples of different proportions of biochar. |
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