THE PHYSICAL AND CHEMICAL-PROPERTIES OF SYNTHETIC AND NATURAL JADEITE FOR JEWELRY

Jadeite was synthesized from its glass of stoichiometric composition NaAlSi2O6, and a colouring agent Cr2O3 (0.3-0.6 wt%) was added to achieve the emerald colour. The conditions employed were a pressure range of 3.0-5.0 GPa and a temperature range of 1150

The influence of topography and land use on water quality of Xiangxi River in Three Gorges Reservoir region

A self-organizing map (SOM) was used to cluster the water quality data of Xiangxi River in the Three Gorges Reservoir region. The results showed that 81 sampling sites could be divided into several groups representing different land use types. The forest dominated region had low concentrations of most nutrient variables except COD, whereas the agricultural region had high concentrations of NO3N, TN, Alkalinity, and Hardness. The sites downstream of an urban area were high in NH3N, NO2N, PO4P and TP. Redundancy analysis was used to identify the individual effects of topography and land use on river water quality. The results revealed that the watershed factors accounted for 61.7% variations of water quality in the Xiangxi River. Specifically, topographical characteristics explained 26.0% variations of water quality, land use explained 10.2%, and topography and land use together explained 25.5%. More than 50% of the variation in most water quality variables was explained by watershed characteristics. However, water quality variables which are strongly influenced by urban and industrial point source pollution (NH3N, NO2N, PO4P and TP) were not as well correlated with watershed characteristics.

Spatial and temporal flows of China's forest resources: Development of a framework for evaluating resource efficiency

Science & Technology Basic Work Program of China: Scientific Survey of the Middle-lower Reaches of Lantsang River and the Great Shangri-La Region [2008FY110300]; National Basic Research Program of China (973 Program): Ecosystem Services and Ecological Safety of the Major Terrestrial Ecosystems of China [2009CB421106]; National Natural Science Foundation of China [30670374]; EU ; European Commission, DG Research [003874]

Comparison of effectiveness of different ashing auxiliaries for determination of phosphorus in natural waters, aquatic organisms and sediments by ignition method

An improved method for the determination of phosphorus in natural waters, aquatic organisms and sediments by ignition method is proposed. The recoveries of phosphorus (P) from selected inorganic and organic P-containing compound standards after ignition with different auxiliaries, such as MgSO4, Mg(NO3)(2), MgO2, Mg(Ac-2) and CaCl2, were compared. We found that the phosphorus from most compound standards could not be completely recovered when these compounds were ignited (450-500degreesC) with the MgSO4 as auxiliary and the baked residue was extracted with 0.2 mol l(-1) HCl for 30min at 80degreesC or at room temperature. P recoveries, for example, were poor, less than 85%, if pyrophosphate and metaphosphate were ignited with the addition Of MgSO4 prior to the extraction of the baked residue with 0.2 mol l(-1) HCl at 80degreesC for 30 min. In contrast, MgO2, Mg(Ac)(2) and CaCl2, as well as Mg(NO3)(2), could all yield complete P recoveries at routine ashing temperatures (450-500degreesC). The results demonstrate that MgC12 is a more effective auxiliary agent for the determination of phosphorus in natural waters, aquatic organisms and sediments by ignition method than MgSO4 which is commonly used. (C) 2003 Elsevier Science Ltd. All rights reserved.