| Selenium is an essential trace element for human body, in the recent years, with gradually deepened understanding of the trace element selenium, selenium is gradually attracted widespread attention. The level of the content of selenium in the environment has a direct impact on a variety of living organisms health, selenium deficiency or excess will cause the body to produce disease, serious lack of selenium can cause endemic diseases such as Keshan disease and Kashin-Beck disease, an appropriate amount of selenium is not only can promote the growth of crop metabolism, increase crop yields and quality, but also enhance animal and the human immune system, play a role in the prevention of many diseases. Soil is an important hub of the ecological environment, content and form of selenium in the soil directly affect plant absorption of selenium, while the plant is either selenium or selenium overdose, will affect the growth, development and reproduction of themselves and their animals, and finally through the food chain and affect human health. Selenium distribution on Earth widely but very unevenly around the world2/3of selenium,1/3the world recognized as a serious selenium District selenium a serious threat to human health and the development of animal husbandry. Therefore, the amount of selenium to promote human health is particularly important. China about72%of the counties there are different levels of selenium phenomenon, about more than700million people in the dietary pattern of the selenium content, resulting in low body selenium status, so rich in selenium industry to build and develop to become the research focus of the current domestic rich in selenium industry development in basic scientific research as the basis, so rich in selenium areas of geology, environment and agriculture is extremely urgent.Enshi is the most typical of the most rich in selenium, Enshi Prefecture's well-known at home and abroad, breaking the nearly200years,"selenium can not be a separate industrial deposits" theory because so far the only independent selenium deposits found in Enshi,2011international human and animal trace element Nutrition Society was officially awarded the "World selenium" in the title,73%of the total area of Enshi Prefecture Chonju soil belong to the high-selenium area, the grade of between230to6300g/ton, Enshi selenium resources development and application of the current and even future Enshi city government even is also a major national strategy to rich in selenium product development early practice has proved rich in selenium food is difficult to achieve development in the high selenium in natural soil conditions. Therefore, you need to be adjusted on the soil to nurture the rich to get a large area of security, stability, controllability selenium soil of agricultural products.In this paper, the basic principles of environmental geochemistry and agricultural geochemistry were combined with new ideas and new methods of selenium study at home and abroad, using field surveys and laboratory experiments a combination of methods to carry out a systematic investigation and research in Enshi typical rich in selenium, the paper the Enshi rich in selenium soil and plant research, Selenium and its associated beneficial and harmful elements in the migration and transformation of its main influencing factors in the systematic investigation of selenium-rich strata-tillage soil-plant system with a soil rich in selenium. Ecological geochemical assessment, proposed the coping strategies of the advantages of selenium-rich land resources planning proposals and government enterprises, provide a scientific basis for the development of our country rich in selenium green regions rich in selenium industry.Obtained the following conclusions and understanding:(1), Using the choice of nitric acid-perchloric acid-hydrofluoric acid, electric hot plate method digestion atomic fluorescence spectrometry method for the determination of total selenium in parts of the soil in Enshi, to optimize the conditions established by hydride generation atomic fluorescence determination of the total selenium content in the sample. The best test conditions, the method detection limit was0.09μg L-1, the linear range of0.12μg·L-1～100μg·L-1, the recovery rate of97.8%to101.1%. Using this method for the determination of the the Enshi parts of the total selenium content of soil, plants, food and other samples. The results show that relatively large differences of soil, plants and food of the total selenium content of Enshi in different parts of the state of nature. Yutangba high-selenium areas, soil and food Se than higher, there is the risk of selenium poisoning. Gyokuro tea garden soil artificially adjusted Enshi banana, tea selenium content is relatively stable.In Enshi rich in selenium product development can take advantage of the selenium content in the middle under the soil to adjust to a more secure Selenium Enriched Foods.(2), By analyzing the composition of selenium-rich black shales, the chemical composition of the rock samples in the main content of48.37-87.83%SiO2, followed by0.99-10.07%Al2O3, CaO and Fe2O3content,0.12-5.22%and0.26-2.32%, the other oxide components of the content is relatively low. Rock samples in the study area generally enriched in B, Cd, Cr and Cu, Ni and Pb, Sn, Tl, V and of Se, the average concentration to reach25.52mg/kg,11.75mg/kg,296.25mg/kg,66.29mg/kg,46.35mg/kg,76.93mg/kg,15.53mg/kg,554.74mg/kg,667.73mg/kg and125.11mg/kg, these data and the average upper continental crust, respectively, compared to1.7times,119.9times,8.47times and2.65times,2.32times and3.85times,2.82times and739.65times,11.13times and2502.2times.(3), Study the Enshi from three typical soil properties and total selenium found selenium content in the fish the embankments area soil, reaching a high selenium levels, the banana region, compared with the ordinary rich in selenium region, long flat region selenium is clearly insufficient. In addition, the the Enshi three soil selenium and organic matter content showed a significantly correlated, indicating that the Enshi soil selenium and organic matter in combination with the part more, which affects the plants can directly use the proportion of selenium. Taking into account the ecological benefits of organic matter content of selenium has a dual nature, on the one hand, as clay adsorption of an organic-inorganic complex environment of selenium, but under certain conditions to adsorption of selenium released, which is conducive to the cycle of selenium, but when it only as an anion environment places the body, it may become the barrier of the selenium transmission cycle, so the organic matter has the duality of the ecological effects of selenium.(4), Enshi typical rich in selenium plant selenium contained in tea is generally low, some samples can not even detected, indicating that the tea rich in selenium capacity is not very strong, some samples did not meet the richselenium tea standards. Rich in selenium plants containing selenium content in the blue dish was as high as tens of ppm, indicating the blue dish containing long-term growth in high-selenium area of the fish embankments near the plants has been tolerated selenium accumulated genes, this is the nature of long-term the result of evolution, the high enrichment of selenium by this plant can be extracted out of organic selenium compounds, which can be made into a variety of biological agents, agricultural researchers have begun to try this kind of wild plants into domesticated crops, allowing large-scale production and extraction of bio-organic selenium, corn, potatoes and soybeans three crops in selenium content slightly higher than that of the selenium content of tea, but far less than the blue dish containing the selenium content.(5), The experiment of single extract of selenium from selenium rich soil was studied, results show that this experiment that2.0mol/L K2HPO4-KH2PO4solution for optimum extraction of the Enshi area of soil available Se for the extraction of soil available selenium agent, the optimum extraction conditions:soil water ratio1:15, extraction temperature is30℃, the oscillation time of120min. Extraction of the surface, the order of selenium in selenium-rich soil rich in selenium in soil, the proportion of the vast majority of the residual selenium, and they mainly occur in the mineral lattice, can not enter to be absorbed by plants into the environment and use of a smaller proportion of water soluble and exchangeable selenium.(6), Heavy metals in selenium rich soil was continue to study the fish embankments heavy metal pollution levels have reached a very high level, especially Cd pollution through to reach its serious stage, Cd exceeded the multiple the most serious, reaching8-800times, followed by Ni pollution, but the effect is minor, in addition, the heavy metals in fish embankments of Cu, Zn, Cr, also exists the problem of excessive, so the fish embankments area planted crops, pay special attention to heavy metal elements, especially Cd pollution as a preventive measure to ensure that the output of food security.(7), Selenium rich in plant cultivation experiment, two different forms of selenium fertilizer compared, that is applied to the soil solid selenium fertilizer and plant pages spraying liquid selenium fertilizer comparative study of selenium in plants migration and distribution, the results show that liquid selenium fertilizer sprayed directly on plant leaves can effectively improve the efficiency in the use of selenium fertilizer, the selenium content of edible parts of plants can quickly and significantly improve traditional fertilization methods directly to the activation of selenium ore facilities to join the soil is much less efficient. For applying selenium fertilizer plant in the soil content of selenium in plant roots soil selenium content of plants, roots, stems and leaves showed a significant positive correlation, correlation coefficients were r=.933(p≤0.01), r=0.922(p≤0.01) and r=0.754(p≤0.05), while the content of selenium in the plant pulp and root soil content of selenium is no clear correlation. In addition, selenite absorption by plant roots from the soil, exist roots and the formation of the selenium compounds, making it difficult to migrate upward served on the plants, and vegetative organs. Page foliar application of selenium fertilizer directly from the stomatal be absorbed into the plants, sent to the edible parts of plants, selenium is more efficient and effective, and therefore even better than from the root absorption.(8) For the development of the rich in selenium industry, I proposed the following measures:a scientific research foundation. The first detailed geological survey work, to find out their family property, such as selenium-rich rock distribution, mineable reserves estimates, the low-selenium coal gangue comprehensive utilization, and other geological research. Second, we must be rich in selenium soil survey, use and planning. Finally, in the breeding and cultivation of improved varieties of crops.2,promotion planning grasp the market.3,government enterprise collaboration. |
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