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151.
The layered laurylsulfonate intercalated green rust (lauryl-S GR) was synthesized to evaluate the influence of synthesis parameters and aqueous conditions on the adsorption of CeIV. The maximum adsorption capacity of 305.58 mg/g by lauryl-S GR was predictably obtained. The pseudo-first-order kinetic model was appropriate in fitting the whole uptake process in a weak acid environment. Three isotherm models including Langmuir, Freundlich, and Tempkin were all reliable in depicting the isotherm adsorption process. The maximum monolayer adsorption capacity of lauryl-S GR towards CeIV was 315.46 mg/g. Ce species including CeO and Ce2O3 besides CeO2 were matched in the XPS distribution, directly indicating the reduction reaction brought by FeII in the GR occurred to hydrated CeIV ions during the adsorption. Nano-sized Ce particles attached to the lauryl-S GRs after the adsorption experiments were observed in the morphological characterization. Flocculated materials were formed on the surface of the lauryl-S GR at a pH of 7, which further reduced the active sites and disrupted the continuous uptake of CeIV to the lauryl-S GR. This study expands the application of GRs and supplies an ideal iron-based material for the construction of the affiliated recovery pathway to the traditional separation of Ce. 相似文献
152.
Chemical and colloidal analyses of natural seep water collected from the exploratory studies facility inside Yucca Mountain,Nevada, USA 总被引:1,自引:0,他引:1
Cizdziel JV Guo C Steinberg SM Yu Z Johannesson KH 《Environmental geochemistry and health》2008,30(1):31-44
Yucca Mountain is being considered as a geological repository for the USA’s spent nuclear fuel and high-level nuclear waste.
Numerous groundwater seeps appeared during March 2005 within the exploratory studies facility (ESF), a tunnel excavated in
the mountain. Because of the relevance to radionuclide transport and unsaturated zone-modeling studies, we analyzed the seep
samples for major anions and cations, rare earth elements, and colloids. Major ion species and elemental concentrations in
seep samples reflect interaction of the water with the volcanic rock and secondary calcites. Elemental fractograms from flow-injection
field-flow fractionation ICP–MS scans detected Br, Ca, Cl, Cu, Fe, I, Mg, Si, Sr, W, and U at void fractions, suggesting they
may be present in the form of dissolved anions. Colloids approximately 10 nm in hydrodynamic diameter, possibly calcite, were
also present in the seepage samples. Geochemical calculations indicate, however, these may be an artifact (not present in
the groundwater) which arose because of loss of CO2 during sample collection and storage. 相似文献
153.
地球系统工程与区域环境问题调控的原则 总被引:2,自引:2,他引:0
论述了地球系统科学和工程研究的发展历史、研究对象和方法,及其在解决全球性环境危机中的作用;阐述了提高共识、言行一致、保护全球公共资源、实现可持续性目标等地球系统工程的基本原则. 论述了区域性与地球系统环境问题间的关系,提出区域环境问题调控的4条基本原则:系统性调控、区际公平、多方合作、综合手段和共同约束. 指出应注重应用地球系统科学与工程的理论与方法解决区域环境与生态问题;应深入探讨地球系统及区域环境与生态压力在中国现阶段的特征,统筹全局与长远调控区域环境问题;应开展长期连续观测和信息共享,创新调控全球与区域环境与生态的技术、方法. 相似文献
154.
华南东部主要铀矿区居民室内外氡浓度研究 总被引:1,自引:0,他引:1
对华南东部6个铀矿区居民室内外空气氡浓度及其变化规律进行了研究。矿区废渣和坑道口释放出来的氡气对周围大气形成了氡污染,特别是在矿区周围0.5~1.5 km的范围内的污染严重。但是空气中的这种氡污染随离矿区的距离增大而迅速减弱。矿区周围居民室内氡的浓度高,是广东省室内氡浓度平均值的10倍左右。在进行调查的190个居室中,有45个(23%)居室室内氡浓度超过美国环境保护局制定的148 Bq/m3室内氡浓度的上限值。居室中氡浓度的升高,除了受矿区释放出来的氡污染外,更主要是因本地区属高本底辐射区,房基下的土壤、岩石和建筑材料中的铀、镭等放射性元素的含量高,其放射性衰变产生的氡释放出来进入室内。 相似文献
155.
稀土元素的骨蓄积性、毒性及其对人群健康的潜在危害 总被引:10,自引:0,他引:10
综合论述了稀土元素在机体内的蓄积性及其毒性效应,分析了稀土农业应用对生态环境和人群骨系统健康的潜在危害.稀土元素被长期低剂量摄入,可在骨组织中蓄积,导致骨组织结构变化,骨髓微核率增高,产生遗传毒性. 相似文献
156.
157.
四川及重庆蕨类植物区系组成、特有现象和珍稀种类 总被引:2,自引:0,他引:2
四川及重庆为我国蕨类植物最丰富的区域之一,总计有52科,141属,约880种。鳞毛蕨科、蹄盖蕨科和水龙骨科是最重要的3个科,其种数占本区种数的50.5%,金星蕨科、中国蕨科和铁角蕨科在本区也有较多的种类分布。在本区主要的属为耳蕨属、鳞毛蕨属和蹄盖蕨属,它们的种数都超过50种,合计占本区种数的22.8%,其次有铁角蕨属、瓦韦属和毛蕨属,其种数都逾25种,而有近85%的属不足10种。热带成分的属在本区占53.9%,但它们的区系存在度不大;东亚分布的属占16.3%,其区系存在度相对较大;温带分布的属占12.7%。本区无特有科;仅光叶蕨属1个特有属,还有6个中国特有属;有387种为中国特有种,约占本区种数的44%。特有种的32%为本区特有,其余以与中国西南片区(占22.5%)和整个南方片区(占26.1%)共有为主。本区被列入国家重点保护的珍稀濒危蕨类植物有10种,其中1级3种,2级7种。 相似文献
158.
V. I. Zabelin 《Russian Journal of Ecology》2007,38(5):347-352
Ecological conditions for the Altai snowcock and the history of formation of its range in the Altai-Sayan mountain region are discussed. The range of this species extends mainly over mountain massifs surrounding the Great Lakes Basin in western Mongolia and the Tuva Basin. These regions are characterized by broken relief with steep slopes. Snowcocks populate both humid high-mountain areas of the Alpine type and dry-steppe areas in middle and low mountains. Expansion of this species to the Altai-Sayan region is attributed to Miocene-Pliocene aridization well manifested in central Asia. The recent distribution of the Altai snowcock over different altitudinal belts is explained by alternation of glaciations and interglacial periods in the Pleistocene and anthropogenic impact in the Holocene. The total abundance of this rare species is estimated at 10000–12000 individuals. 相似文献
159.
I. V. Shtangeeva 《Chemistry and Ecology》1995,11(2):85-95
Neutron activation analysis was used for the determination of the elemental composition of different plants and soils. Variations in concentrations of elements during the day were found. Mean concentrations, standard deviations and relationships between elements in soils and different parts of plants were studied. It was shown that the behaviour of chemical elements in samples from urban and unpolluted areas have significant differences. 相似文献
160.
神农架野生珍稀濒危植物及其保护对策研究 总被引:4,自引:0,他引:4
李兆华 《长江流域资源与环境》1992,1(1):8-54
本文研究表明神农架共有国家保护的野生珍稀濒危植物21科26属28种(包括变种)。保护植物之生活型以高位芽植物占绝对优势,花期主要集中于4~5月,果期主要集中于9~11月。本文还从就地保护和迁地保存两方面阐述了珍稀濒危植物的保护对策。 相似文献