稀土元素在土壤-植物系统中行为与归宿的研究

对当前农用稀土安全性评价研究前沿的土壤-植物系统中稀土元素的行为与归宿研究予以综述。归纳出土壤pH、氧化还原电位、有机质、阳离子交换量、粘粒矿物等均影响外源稀土在土壤中吸附性能和迁移性、稀土元素各形态转化与可给性,植株或农作物体内聚集稀土元素的能力依赖于植物种类、土壤介质中稀土含量以及成土母质和相应的生境。与土壤介质相比,植株中单一稀土元素含量可存在一定的分异性,并且植株对单一稀土元素的吸收与运移具有选择性。为此有必要从细胞水平和分子水平进一步研究单一稀土元素在植物体内的存在状态和运移特性,同时深入研究稀土肥料的不同方式施用后,田间状况下农作物体内稀土元素的吸收及运移情况,特别是籽实中稀土元素的累积。     

稀土在玉米及水稻中吸收分布与积累规律研究

研究玉米和水稻中５个稀土元素（Ｌａ,Ｃｅ,Ｙ,Ｇｄ）的含量分布以及单一稀土的分布规律。结果表明：玉米和水稻吸收稀土的能力与土壤可给性稀土呈正相关关系,植物体各部位稀土含量分布一般规律为根〉叶〉茎〉时实;单一稀土在根部的分布特征是Ｌａ〉Ｃｅ〉Ｎｄ〉Ｙ〉Ｇｄ,在叶、茎、果实的分布特征是Ｃｅ〉Ｌａ〉Ｎｄ〉Ｙ〉Ｇｄ,说明轻稀土较重稀土易被植物吸收。总之,稀土元素在植物中不易迁移,主要集中在根部,果实中含量甚微,因而施用稀土微肥,不会影响食用粮食的安全问题。     

芮玉奎-双价抗虫棉(Bt+CpTI)苗期稀土元素吸收分配特性

了解转基因抗虫棉的稀土元素吸收分配特性对于稀土肥料的高效利用意义重大。应用ICP-MS测定了转基因棉花及其亲本苗期各个器官中稀土元素La、Ce和Pr的含量。结果显示稀土元素在转基因双价抗虫棉和常规棉对照中的分配规律一致:根系>叶片>茎部;每个器官中都是Ce>La>Pr。但是转基因抗虫棉与常规棉相比,在稀土元素的吸收分配比例上却表现出较大差别:转基因抗虫棉根系中稀土元素含量明显高于常规棉亲本;地上部(叶片和茎部)表现相反,常规棉含量大于转基因抗虫棉。转基因抗虫棉稀土元素吸收分配特性发生了明显变化,应当根据其特点制定稀土肥料使用办法。但是发生上述变化的机理需要进一步深入研究。     

Rare gas systematics in popping rock: isotopic and elemental compositions in the upper mantle

New experimental data on the isotopic variations of neon, argon, and xenon in a popping rock imply that the 40Ar/36Ar ratio of the upper mantle is less than 44,000 and that the 129Xe/130Xe ratio is less than 8.2. The elemental abundance pattern of rare gases is chondritic-like and is quite distinct from the solar pattern. These data imply that Earth accreted from planetesimals that probably underwent a transformation of their rare gas budget from solar- to chondritic-like, leaving the isotopic composition unchanged from the solar pattern.     

Samarium-neodymium direct dating of fluorite mineralization

The direct dating of many styles of hydrothermal mineralization has proved difficult, limiting understanding of the geological processes that lead to crustal fluid flow and the formation of major ore deposits. The hydrothermal mineral fluorite (CaF(2)) displays large variations in rare earth element (REE) abundance and samarium/neodymium ratios within a single vein. Samarium-neodymium dating of fluorite from the classic granite-hosted tin deposits of southwest England demonstrates its use as a precise chronometer of mineralization. The concentrations of light rare earth elements (LREEs) in the fluorites are highly variable and suggest the coeval precipitation of an LREE-rich phase as the most likely cause of the extreme variation in samarium/neodymium ratios.     

肥料类型对稀土和磷在土壤径流中迁移的影响研究

通过人工降雨模拟试验研究了稀土元素和磷在土壤中横向流失的特征,初步探讨了在不同肥料作用下稀土元素和磷在土壤中迁移的关联性。结果表明,绝大部分稀土元素和磷素都是通过径流沉积物相流失;施入肥料的种类不同对稀土的影响也有差别,磷肥进入土壤后会影响土壤中稀土的化学行为及迁移,同一稀土元素的浓度在有机肥作用下相对较高;试验结果为开展利用稀土多素示踪方法解析粪肥面源来源的可行性研究提供了参考依据。     

Effects of Lanthanum and Cerium on Seeds Fatty Acid Composition in Soybean

Soybean Dongnong 42 from northeast of China was used as an experimental material. The samples were tested by spraying different concentrations of LaCl3, CeCl3 and LaCl3+CeCl3 solutions on the leaves at the seedling stage and the early flowering stage of the soybeans. Gas chromatography was used to determine the fatty acid content and ratio of the soybean seeds at the maturity stage. The fatty acid ratio of soybean seeds were evaluated by calculating saturated fatty acid(SFA), monounsaturated fatty acid(MUFA), polyunsaturated fatty acid(PUFA), unsaturated fatty acids(UFA), UFA/SFA, index unsaturated fatty acid(IUFA) and double bond index(DBI).(MUFA+PUFA)/SFA was used to study the effects of rare earths on the quality of soybean seeds. The results showed that spraying the rare earth solution could significantly optimize the fatty acid distribution ratio of soybean seeds. Compared with the control group(CK), stearic acid was reduced by 5% and linolenic acid was reduced by 3.72%. Except for La10, the oleic acid content increased significantly by 2.22%. Under the treatment of 30 mg·L~(-1) CeCl_3, UFA, UFA/SFA and DBI were 83.56, 5.08 and 9.47, respectively, which were the highest in each group. Under the treatment of 150 mg·L~(-1) LaCl_3,(MUFA+PUFA)/SFA was 4.89, the closest meal to the recommended ratio. The above results showed that spraying appropriate concentrations of rare earth at the seedling stage and the early flowering stage could optimize the fatty acid ratio of soybean seeds and improve dietary fatty acid ratios.     

稀土在畜牧业生产中应用的研究

本文根据河南省的稀土资源以及自然特点，把河南省的土地划分为5个区域，在这5个区域的内对稀土在牧草以及饲料作物的有效范围以及利用的可行性进行研究，同时还对稀土在畜牧业中的经济意义进行了综合评价，对其在畜牧业中的广泛推广提供依据。     

稀土元素在金针菇栽培上的应用研究

本文报道了不同种类稀土及施用浓度对金针菇的生长效应及其改善品质的作用。试验结果表明，适宜浓度的稀土元素添加于培养料中，能明显促进金针菇菌丝体的生长发育，提高金针菇的相对和绝对生物学效率，并对改善于实体的品质具良好效果。     

农用稀土对大田玉米中稀土元素分布的影响

以潮土为例，采用田间试验方法，研究了农用稀土施加后不同时期大田玉米体内16种稀土含量的变化。结果表明，所施稀土很快地被玉米根系吸收并运移到地上部分。根系中稀土含量存在显著的剂量-效应关系。并不随玉米生育期而发生明显变化，但玉米生长可显著影响到地上部分稀土的分布，尤其在低剂量稀土作用时。稀土肥料施用后玉米体内单一稀土含量依根系≥叶〉茎〉籽实的顺序减少；玉米体内La的吸收和运移明显快于Ce和Sm，并随生育期而发生变化；土壤中Gd较容易被玉米根系吸收并转移到地上部分。在此实验条件下，农用稀土施加后玉米体内单一稀土的吸收和运移具有选择性，随玉米生育期而发生变化；根系中单一稀土限口La、Ce和Sm）的选择性积累可能存在一种动态平衡。     

Instrumental neutron activation analyses of lunar specimens

Ten Apollo 11 specimnens were divided into 24 samtples. Sodillim contents of 8 diverse specimens clluster tightly abolit 0.3 percent. Plagioclase separated from sample 10044 contains aboltt 1.09 percent Na; barium is not enriched in the plagioclase separate. Contents of the rare earths are strikingly high, and relative abtmndances resemble those of calcium-rich achondrites or abyssal basalts but are depleted in Eu by factors of 2 to 3 and in La by about 20 percent. The plagioclase separate is enriched in Eu and pyroxenes (and opaqtte minerals are Eu-depleted. Fine fractions of 10044 are abotit 20 to 40 percent richer in most rare earths (50 percent for Eu) than coarse fractions, probably becaitse of the presence of small grains in which rare earths are mnarkedly concentrated. "Microgabbro" 10045 is imnpoverished, relative to the soil, in rare eartlhs and Hf. Ratios by mass of Zr to Hf are comlparatively low. Abttndances of Mn, Co, Fe, Sc and Cr stiggest systematic differences between igneous rocks on one hanid and breccias and "soil" on the other. Fromn the Co abuindances, no more than about 3 percent of the present "soil" can consist of chondritic mleteorite conitamination.     

耕型红壤和红壤性水稻土铜的化学行为及施铜效应研究

应用选择溶解性的化学提取和幼苗试验等方法,研究了湖南省几种耕型红壤及其发育而成的水稻土铜的化学形态及其与土壤有效铜的关系,以及红壤旱地改水田后施铜对水稻吸铜和幼苗生长的影响．结果表明,供试土壤中的铜主要以有机态（１５．２％ ）、无定形铁态（１１．７％ ）、晶形铁态（１７．２％ ）和残留态（５６．０％ ）４ 种形态存在,其中红壤性水稻土有机态铜（１８．７％ ）和无定形铁态铜（１４．６％ ）明显高于耕型红壤（分别为８．０％ 和５．８％ ）,而晶形铁态铜和残留态铜含量则是后者高于前者．红壤性水稻土有效铜含量显著高于耕型红壤．幼苗试验结果表明,耕型砂岩红壤施铜能明显促进水稻幼苗对铜的吸收,最佳施铜量为 ５～１０ ｍ ｇ／ｋｇ 土．     

Fly ash-derived strontium as an index to monitor deposition from coal-fired power plants

The combustion of western U.S. coals releases significant amounts of strontium, which is relatively enriched in the fine particles of fly ash. Fly ash-derived strontium is readily absorbed by agronomic and native plant species when incorporated in soil. The strontium-87 to strontium-86 ratios of fly ash and soils were significantly different, but similar ratios were found in fly ash and plants treated with fly ash. A technique for measuring and monitoring deposition from coal-fired power plants is inferred from the enhanced plant uptake of fly ash strontium and the similarity in the isotopic ratios of fly ash and treated plants.     

Airborne studies of the smoke from the kuwait oil fires

Airborne studies of smoke from the Kuwait oil fires were carried out in the spring of 1991 when approximately 4.6 million barrels of oil were burning per day. Emissions of sulfur dioxide were approximately 57% of that from electric utilities in the United States; emissions of carbon dioxide were approximately 2% of global emissions; emissions of soot were approximately 3400 metric tons per day. The smoke absorbed approximately 75 to 80% of the sun's radiation in regions of the Persian Gulf. However, the smoke probably had insignificant global effects because (i) particle emissions were less than expected, (ii) the smoke was not as black as expected, (iii) the smoke was not carried high in the atmosphere, and (iv) the smoke had a short atmospheric residence time.     

江西省土壤可溶态稀土元素含量和分布规律的研究

对江西１１种母质发育有代表性的水稻土、旱土、自然土壤,６１个剖面,４１２个土样的可溶态稀土元素分析测定,统计结果表明：江西土壤稀土元素的强度因素处于较高水平,平均值为１９．０ｍｇ／ｋｇ,有４２．８０％的样点处于丰富级;有由南向北,由东向西逐渐降低的趋势。其含量最高的地区是赣南由花岗岩、泥质岩、第四纪红粘土、酸性紫色土、炭质岩类风化物等母质发育的土壤,较低的为赣西北由石英岩,第三纪红砂岩、石灰岩、下蜀系黄土等母质发育的土壤;在土壤剖面分布中,旱地表层低于底层,水稻土表层有生物富集作用高于底层;影响土壤中可溶态稀土元素含量的主要因子有：成土母质,气候条件（温度,降水量）,土壤ｐＨ,土壤质地。     

对氟偶氮氯膦显色剂的光度性能

研究了新显色剂对氟偶氮氯膦(CPA-pF)与稀土元素的显色性能,发现在0.01mol/L HCl酸性介质中,CPA-pF显色剂与15种单一稀土离子的α型显色反应可在瞬间完成,配合物的最大吸收波长λ_(max)为662-666 nm,ε=5.9-8.0×10~4L/mol·cm;在pH4.8的HAc-NaAc介质中,该试剂还能与钇组稀土元素(Gd-Lu,Y)形成更为灵敏的β型配合物,其最大吸收波长λ_(max)为742-748 nm,ε=6.7-11.0×10~4L/mol·cm。不论是α型还是β型配合物都很稳定,至少20h内保持不变。     

稀土元素对植物生物学作用机制的研究进展

稀土元素在农业上得到了广泛的应用,产生了显著的经济效益。人们对稀土元素生物学效应 的作用机制进行了很多研究,提出了许多论点。从稀土元素在植物体内的赋存、稀土元素对植物光合 作用的影响机制、稀土元素对细胞中Ca的竞争取代机制、稀土元素对生物体内自由基的清除机制和 稀土与生物大分子的紧密结合及在细胞水平的定位五个方面综合分析了稀土元素对于植物体作用 机制的最新研究成果,为稀土农用技术的研究提供新的思路。     

Constraints on transport and kinetics in hydrothermal systems from zoned garnet crystals

Zonation of oxygen isotope ratios, fluorine, and rare earth element abundances across garnet crystals from the Permian Oslo Rift reflect temporal variation of the hydrothermal system in which the garnets grew. A sharp rimward decrease in the (18)O/(16)O ratio (of 5 per mil) across the interface between aluminum-rich garnet cores and iron-rich rims indicates influx of meteoric fluids to a system initially dominated by magmatic fluids. This influx may record the transition from ductile to brittle deformation of the hydrothermally altered rocks. In contrast, fluorine and light rare earth element concentrations increase at the core-rim interface. These data may reflect enhanced advective transport and notable kinetic control on trace element uptake by the garnets during brittle deformation.     

稀土元素对农田生态系统的影响研究进展

稀土矿的开采和冶炼、稀土农用等导致农田土壤稀土元素含量不断积累,对农田生态系统结构和功能稳定产生严重的影响。综述了近20年来国内外农田生态系统稀土元素的主要来源、分配和输出,土壤和植物中稀土元素的测定方法,稀土元素对农田生态系统中植物、微生物、动物以及人类健康影响的研究进展。探讨了农田生态系统稀土元素的毒性评价和稀土污染土壤的修复措施。最后提出开展稀土元素对农田生态系统影响研究还需要加强的一些问题。