典型生态地带硒元素生物有效性的控制机理研究

发布时间：2018-06-30 05:18

本文选题：生物有效性 + 生物可及性　；参考：《中国地质大学(北京)》2016年博士论文

【摘要】：大骨节病(Kaschin-Beck disease)是分布于低硒带上典型的地方性骨关节疾病。但对于局部地区来说,土壤低硒并不一定是大骨节病重灾区,硒的生物有效态比例,尤其是水溶性硒在总硒中的占比更为关键。本文通过开展四川阿坝州、青海兴海大骨节病高发区与青海平安富硒健康区等生态景观典型地带生态地球化学评价,对大骨节病与生态地球化学环境的关系、与大骨节病有关的有益有毒有害元素分布与成因来源、迁移转化及影响机制的进行研究分析,旨在探讨硒的生物有效性、生物可及性对大骨节病等生态效应的控制。研究发现,大骨节病多发的四川阿坝典型地区具有高F低Se以及低水溶性总硒的特征,腐殖酸态硒Humic(Se)是大骨节病对照区土壤中贡献最大的土壤水溶性硒组分,其次是溶解性、流动性较佳的硒酸盐态硒Se(VI),并且有效P对腐殖酸态硒的进一步活化起了促进作用;而大骨节病区的土壤水溶性总硒由于亚硒酸盐态硒Se(IV)而受限明显,铁氧化物/氢氧化物与有机质很大程度上约束了亚硒酸盐态硒Se(IV)的生物活性;在大骨节病高发的四川阿坝地区与青海兴海地区农产品安全性较为良好,但其中硒的含量普遍偏低,病区的主要农作物(青稞、马铃薯等)对硒的富集效应受土壤p H值、交换性Ca、交换性Mg等的强烈制约;此外,四川阿坝大骨节病区的居民日均摄入I、Se的量相比健康生态的青海平安-乐都地区偏低,且大骨节病发病区的居民较对照区的居民Se摄入明显不足,且呈现低钙高锶的特征,大骨节病重病区的居民硒的暴露水平与蓄积水平与对照区相比也明显不足。化学蚀变指数CIA与ICV指数的计算证明了阿坝地区土壤低硒水平很大程度上是对成土母质的继承。对于不同类型的土壤,元素地球化学行为的受制因素也有较大差异:如寒冻雏形土(M1)表层土壤硒Se(VI)的淋滤或下渗作用是硒生物有效性降低的主要制约因子。此外,山腰处的干润均腐土(J2)由于降水作用导致表层土壤中Ca(HCO3)2协同易溶的K、Na、Cl、S或Se等盐类不断下渗淋失,而在低洼山谷或沉积区则残留下Ca CO3、Mg CO3等在土壤胶体表面富集(钙积现象);湿润淋溶土(L4)典型的粘化层则是抑制Se(IV)活性的重要束缚因素;高原厌氧环境下的滞水潜育土(I2),有机质含量丰富且沼泽泥炭发育、排水不良,这样的酸性土壤水溶性总硒含量虽高,但高的腐殖质含量也同样可能致大骨节病,是大骨节病病区典型的自然地理特征之一。研究成果将为调控和改善低硒地区生态环境以及科学开发富硒地区农产品提供依据,具有重要的实际应用价值和科学意义。
[Abstract]:Kaschin-Beck disease (Kaschin-Beck disease) is a typical endemic osteoarticular disease distributed in low selenium belt. However, for local areas, low selenium in soil is not necessarily the most serious area of KBD, and the proportion of available selenium in organisms, especially the proportion of water-soluble selenium in total selenium, is more critical. The relationship between Kashin-Beck disease (KBD) and ecological geochemical environment was evaluated in the typical areas of ecological landscape such as Aba Prefecture of Sichuan Province, high incidence area of Kaschin-Beck disease in Xinghai, Qinghai Province, and healthy area of Ping'an selenium rich in Qinghai Province. The distribution, origin, migration and transformation of beneficial toxic and harmful elements related to Kaschin-Beck disease (KBD) were studied and analyzed in order to explore the biological availability of selenium and the control of biological accessibility to KBD. It was found that the typical areas of Aba, Sichuan Province, where Kaschin-Beck disease occurs, have the characteristics of high F, low se and low water-soluble total selenium. Humic acid selenium Humic (se) is the most important component of water-soluble selenium in the soil of Kashin-Beck Beck disease control area, followed by solubility. Selenate se (VI) with better fluidity and effective P promoted the further activation of humic acid selenium, but the total water soluble selenium in the soil of Kashin-Beck disease area was obviously restricted by selenite se (IV). The biological activity of selenite se (IV) is restricted to a great extent by iron oxide / hydroxide and organic matter, and the safety of agricultural products in the high incidence of Kaschin-Beck disease in Aba area of Sichuan and Xinghai area in Qinghai Province is relatively good. However, the selenium content is generally low, and the enrichment effect of main crops (highland barley, potato, etc.) on selenium is strongly restricted by soil pH, exchangeable Caand exchangeable mg, etc. The daily intake of IfSe in Kaschin-Beck disease (KBD) area of Sichuan Province was lower than that in Pan-Ledu area of Qinghai Province, and the intake of se in Kaschin-Beck disease area was significantly lower than that in control area, and it was characterized by low calcium and high strontium. The level of selenium exposure and accumulation in the area of Kashin-Beck disease (KBD) was also significantly lower than that in the control area. The calculation of chemical alteration index CIA and ICV index proves that the low selenium level of soil in Aba area is largely inherited from the parent material. For different types of soils, there are also significant differences in the limiting factors of elemental geochemical behavior: for example, the leaching or infiltration of se (VI) in the surface soil of cold frozen embryonic soil (M1) is the main limiting factor for the reduction of the bioavailability of selenium. In addition, dry humic soil (J2) on the hillside resulted in the continuous leaching of Ca (HCO _ 3) _ 2 and soluble salts such as K _ (Na) C _ (3) S or se in the topsoil due to precipitation. However, in low-lying valleys or sedimentary areas, Caco _ 3, mg, CO _ 3 and so on are enriched on the surface of soil colloid (calcareous phenomenon), and the typical clay layer of wet leached soil (L _ 4) is an important binding factor to inhibit se (IV) activity. In the stagnant soil (I _ 2) in the anaerobic environment of plateau, the organic matter is abundant, the bog peat is developed and the drainage is poor. Although the water soluble total selenium content of such acidic soil is high, the high humus content may also cause Kaschin-Beck disease. Kaschin-Beck disease is one of the typical physical and geographical characteristics in the area of Kaschin-Beck disease. The research results will provide the basis for regulating and improving the ecological environment in the low selenium area and developing agricultural products in the rich selenium area scientifically, which has important practical application value and scientific significance.
【学位授予单位】：中国地质大学(北京)
【学位级别】：博士
【学位授予年份】：2016
【分类号】：S153

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