Sorption Characteristics of Rare Earth Element Eu^3＋ onto Silica-Water Interfaces Studied by Fluorescence Spectroscopy

The sorption of Eu species onto nano-size silica-water interfaces was investigated using fluorescence spectroscopy for Ph ranges of 1-8.5 and an initial Eu concentration (Ceu) of 2×10-4 M. The sorption rate of Eu was initially low, but significantly increased at Ph>4. The sorption density of Eu species on a silica surface was ～1.58×10-7 mol/m2 when the dissolved Eu species were completely sorbed onto silica-water interfaces at Ph=～5.8. The sorbed Eu species at Ph<6 is aquo Eu3 , which is sorbed onto silica-water interfaces as an outer-sphere complex at Ph<5, but may be sorbed as an inner-sphere bidentate complex at 5相似文献   

Late Quaternary downcutting rates of the Qianyou River from U/Th speleothem dates, Qinling mountains, China

Dating deposits in caves formed by rivers may yield insight into rates and processes of bedrock incision. Three cave passages at different levels have developed in the walls of the Qianyou River valley in the Qinling mountains, south of the city of Xian, China. Twelve speleothem samples near the position of palaeowater tables in three cave passages are dated by the ²³⁰Th dating method. The results show that the river cut down at the rate of 0.23 ± 0.02 mm/yr from 358,000 ± 38,000 to 247,000 ± 28,000 yr ago, 0.19 ± 0.03 mm/yr from 247,000 ± 28,000 to 118,000 ± 19,000 yr ago, and 0.51 ± 0.08 mm/yr from 118,000 ± 19,000 yr ago until today. These fall very close to the glacial-interglacial transition following marine oxygen isotope stages 10, 8, and 6, respectively. The increase in downcutting rates during the interglacial period is consistent with warm, wet weather, increasing rates of erosion. This may lead us toward an underlying mechanism for modulating incision that is not in a direct response to the presence of headwater glaciers.     

Crustal and mantle strengths in continental lithosphere: is the jelly sandwich model obsolete?

The relative importance of the contribution of the lower crust and of the lithospheric mantle to the total strength of the continental lithosphere is assessed systematically for realistic ranges of layer thickness, composition, and temperature. Results are presented as relative strength maps, giving the ratio of the lower crust to upper mantle contribution in terms of crustal thickness and surface heat flow. The lithosphere shows a “jelly sandwich” rheological layering for low surface heat flow, thin to average crustal thickness, and felsic or wet mafic lower crustal compositions. On the other hand, most of the total strength resides in the seismogenic crust in regions of high surface heat flow, crust of any thickness, and dry mafic lower crustal composition.     

Coastline configuration and geomorphologic development mode of arc-shaped coast in South China

1IntroductionArc-shaped bays are quite common on exposed sediment coast in South China, where the crenulate-bay beaches occur with the presence of two consecutive headlands and a predominant wave approach oblique to the alignment of the upcoast and downcoast headlands (Yasso, 1965). Oblique persistent swell striking a shoreline transports sediment alongshore and sculptures a coast into arc-shaped beaches. The shoreline of beach appearance mainly consists of straight segment and shadow segment…     

宁夏中北部地区沙尘暴天气发生过程中的不稳定条件分析

从沙尘暴的形成条件入手，对宁夏中北部地区近30a来沙尘暴天气发生过程中的不稳定条件进行了较为详尽的分析。结果表明：沙尘暴发生三前，大气的不稳定性明显增强；沙尘暴天气发生时不稳定性主要发生在700hPa以下，最为突出的是850hPa以下；沙尘暴发生过程中不稳定性达到最强。     

武汉地铁及长江隧道沿线地下管线现状分析

本文论述了利用城市地下管线信息系统对武汉地铁和长江隧道沿线进行地下管线现状调查的过程和方法，结果表明利用该系统所完成的分析和成果资料满足了武汉及长江隧道沿线工程可行性研究的需要。     

地心非旋转坐标系中的TWSTT计算模型

根据卫星双向时间传递(TWSTT)的基本原理，详细推导了地心非旋转坐标系中TWSTT的计算模型．并与地固系中的计算模型进行了分析比较，证明了两种计算模型在0．1ns亚纳秒量级上的等价性。     

一种改进的MODIS影像BRDF辐射校正方法

针时二向性造成的辐射失真，在核驱动模型的基础上提出了一种改进的二向性反射分布模型，并通过时MODIS影像的试验，得到了减弱辐射差异的较好效果，并对试验结果进行了分析和评价。