<p>&#160; &#160; Knowledge of the volatiles cycles is vital to understand the evolution of the planet Earth and the life it supports. Although it is gradually accepted that water and other volatiles are recycled into the mantle through subduction, it is still not unclear how these volatiles are transported down into the deep Earth. Phlogopite is an accessory mineral frequently observed in samples from the upper mantle, thereby acting as an important carrier of fluorine and water down to >200 km depth. Previous experimental studies and textural relationships of natural samples have indicated that fluorine-rich phlogopite can be stable under ultra-high-temperature conditions. To further investigate effects of fluorine on the stability of phlogopite, here, we present an atomic level research of effects of fluorine on the structural stability using in situ high temperature infrared spectroscopy, Raman spectroscopy, and X-ray powder diffraction. Both X-ray powder diffraction and Raman spectroscopy suggests that fluorine-poor phlogopite decomposes earlier than the fluorine-rich phlogopite. Moreover, the O-H bonds and lattice modes are stiffer for the fluorine-rich phlogopite than the fluorine-poor phlogopite, which is well responsible for the mechanism of fluorine stabilizing phlogopite. Based on our studies, we propose that fluorine-rich phlogopite can effectively transport water and fluorine to the deep Earth.</p>
Selective oxidation of methane to methanol has been often considered as a "holy grail" reaction in catalysis. Herein, we systematically investigate the effect of solution pH and Pd-to-Au ratio of AuPdx colloid on the catalytic performance of methane oxidation. It is revealed that these two parameters can determine the amount of H2O2 participated in the reaction, which is linearly related to the productivity of oxygenates. A high catalytic performance in methane activation requires a high utilization of H2O2 to generate more ·OH. The optimal pH is 3.0 and the optimal Pd-to-Au ratio is between 0.1 to 0.7.
Many kinds of construction wastes are now produced in China. Recycling disposal of construction wastes not only alleviate pressure on the environment but also identify certain economic and social benefits. This paper undertakes a timely review of recycling disposal of construction waste in China's Road Construction Industry. The paper presented definitions of construction wastes and described the current situation of construction wastes in China. Considering the research findings which have been achieved in the field of waste disposal, this paper discussed the approaches to recycle construction wastes in China including abandoned concrete, waste asphalt, old brick, waste timber, sewage sludge. The conclusion makes recommendations that are deemed to offer substantial benefits for both the road construction industry and society as a whole.
The molecular composition and biomarker distribution of various occurrences of organic matter in argillaceous source rocks developed in fresh and saline lacustrine environments were revealed by successive treatments of solvent extraction followed by acid hydrolysis using gas chromatography–mass spectrometry. The free fraction obtained by solvent extraction provided abundant geochemical information concerning the sedimentary environment, thermal maturity and biogenic origin, and obvious differences existed between fresh and saline lacustrine source rock samples. Our research results indicate that the carbonate-mineral-bound (CM-bound) fraction released by successive acid hydrolysis could also serve as a significant biogenic indicator, as the bicyclic sesquiterpenoids, indicative of Botryococcus braunii origin, were specifically detected in quite high abundance in the acid-soluble fraction. In addition, the light end hydrocarbons were much better preserved in the acid-soluble fraction, and elemental sulfur was only detected in the CM-bound fraction, suggesting a relatively confined environment for the CM-bound fraction, which thus could preserve additional geochemical information compared to that of the free fraction. The CM-bound fraction also exhibited discernable differences between fresh and saline lacustrine samples. Therefore, it can be concluded that comprehensive analysis of free and CM-bound fractions in the argillaceous source rocks can provide a more authentic and objective interpretation of geologic conditions.
Soil samples(197) were collected from the main areas(14 counties) of the Chengdu plain and the spatial distribution and pollution assessment of soil arsenic in the plain were investigated.The result,based on the methods of chemical analysis and mathematical statistics,showed that the range of soil arsenic content was from 3.00 to 20.57mg/kg,and the average value was 10.41mg/kg.The content of different counties varied significantly,The arsenic content increased progressively from northwest to the southeast spatially.The results of pollution assessment indicated that As content in only 15.74% samples surpassed the standard of grade 1 level in the Soil Environment Quality Standard,and only 1 sample surpassed grade 2.The extent of influence by human activity was from grade 1 to grade 3,but mostly by grade 1 level,which was the transition level of pollution.
Water release in subduction zones is not only an important part of the deep Earth’s water cycle, but also plays an essential role in the physical and chemical properties of rocks constituting the deep Earth. To understand water release processes, it is important to know properties of dehydration in hydrous phases of the downgoing slab. Although it is widely accepted that phengite can be stable to greater depth in subduction environment, behavior of hydroxyl and lattice of it at high temperature and high pressure are less investigated in contrast to other hydrous phases. Here, using IR and Raman spectroscopy, we characterize hydroxyl and lattice of ammonium-bearing and ammonium-free phengite at high temperature and high pressure. No proton transferring and structural phase transition in phengite were observed over the measured temperature and pressure range. Both pressure and temperature induce hydroxyl band shifting to lower frequencies, and pressure has a greater impact. The band width of hydroxyl increases with temperature and pressure. Hydroxyl bond weakening and hydrogen disordering at high temperature and high pressure should be responsible for the spectra variations. On the other hand, the lattice modes soften with increasing temperature whereas stiffen under compression, and ammonium plays an important role in the Grüneisen parameters of the lattice modes, especially the K-O mode. These features of hydroxyl and lattice at high temperature and high pressure could benefit for further understanding dehydration, thermodynamic properties and stability of phengite in subduction zones.
This dataset contains all new data corresponding to figures in the manuscript, including in situ high temperature FTIR, Raman data, and breakdown temperature from previous studies and this study.
'/%3e%3cuse xlink:href='%23a' transform='rotate(23.036 .093 25.536)'/%3e%3cuse xlink:href='%23a' transform='rotate(45.87 1.273 16.18)'/%3e%3cuse xlink:href='%23a' transform='rotate(69.945 .996 12.078)'/%3e%3cuse xlink:href='%23a' transform='rotate(20.66 -19.689 31.932)'/%3e%3c/svg%3e)
'/%3e%3c/defs%3e%3cpath fill='%23012169' d='M0 0h10080v5040H0z'/%3e%3cpath stroke='%23fff' stroke-width='.6' d='m0 0 6 3m0-3L0 3' clip-path='url(%23b)' transform='scale(840)'/%3e%3cpath stroke='%23e4002b' stroke-width='.4' d='m0 0 6 3m0-3L0 3' clip-path='url(%23c)' transform='scale(840)'/%3e%3cpath stroke='%23fff' stroke-width='840' d='M2520 0v2520M0 1260h5040'/%3e%3cpath stroke='%23e4002b' stroke-width='504' d='M2520 0v2520M0 1260h5040'/%3e%3cg fill='%23fff'%3e%3cuse xlink:href='%23d' x='2520' y='3780'/%3e%3cuse xlink:href='%23a' x='7560' y='4200'/%3e%3cuse xlink:href='%23a' x='6300' y='2205'/%3e%3cuse xlink:href='%23a' x='7560' y='840'/%3e%3cuse xlink:href='%23a' x='8680' y='1869'/%3e%3cuse xlink:href='%23e' x='8064' y='2730'/%3e%3c/g%3e%3c/svg%3e)