Effects of acid rain on physical,mechanical and chemical properties of GGBS–MgO-solidified/stabilized Pb-contaminated clayey soil     

Du  Yan-Jun  Wu  Jian  Bo  Yu-Lin  Jiang  Ning-Jun 《Acta Geotechnica》2020,15(4):923-932

Acta Geotechnica - Reactive magnesia (MgO)-activated ground granulated blast furnace slag (GGBS) is a newly developed binder for soil stabilization/solidification. It can be used as an alternative...  相似文献   

High pressure geochemistry:Preface     

Jianguo Du  Baohua Zhang  Bo Zou  Bin Chen  Geeth Manthilake 《地学前缘(英文版)》2021,12(2)

The origin and history of the Earth are manifested as the evolutionary processes of chemistry and physics of its interiors,which can be recognized by deciphering the geochemical signals recorded in minerals and rocks.Deep interiors of the Earth and other rocky planets are under both extreme pressure and temperature,i.e.,approximately 360 gigapascals(GPa)and as high as 7000 K at the center of the Earth.  相似文献   

High-pressure phase transformation of carbonate malachite Cu2(CO3)(OH)2 driven by [CuO6] regularization and [CO3] rotation     

Jing Gao  Xueyin Yuan  Bin Chen  Zhenxian Liu  Wen Su 《地学前缘(英文版)》2021,12(2)

High-pressure synchrotron X-ray diffraction and infrared absorption spectroscopy have been employed to study the crystal chemistry and phase transitions in an[OH]-bearing carbonate,malachite Cu2(CO₃)(OH)₂,to determine the effect of[OH]on the stability of carbonate.We found that the crystal structure of malachite is stabilized by a high degree of[CuO₆]-octahedron distortion,as is manifested by large variations in Cu–O bond lengths resulting from oxygen atoms that connect to hydrogen at crystallographically different sites.External pressure offsets the effect of hydrogen bond,promotes[CuO₆]compression and regularization and accordingly[CO₃]rotation.Rotation of[CO₃]-triangles,in turn,assists in a conversion in the crystal orientation of the[CuO₆]structural unit.During compression to above~6 GPa,malachite begins to turn into the rosasite lattice,accompanied with a jump in density of 3.3%.Rosasite is characterized with a hardened lattice and preserves to the maximum pressure(18.2 GPa)of the present study.Phase transformation mechanism of malachite to rosasite is different from that of carbonates,with the latter being driven by an almost uniform compression of[MO₆]-octahedron(M=Ca,Cd,Mn,Fe,Zn,Mg,etc.)and rotation/translation of[CO₃]-triangle under pressure.  相似文献   

Response of ocean dynamics to multiple equilibria of the Kuroshio path South of Japan     

《Dynamics of Atmospheres and Oceans》2019

Variability of the Kuroshio path to the south of Japan plays a central role in the local climate change and exerts tremendous influences on the local atmosphere and ocean. In this study, the response of ocean dynamics, in terms of the eddy kinetic energy (EKE), potential vorticity (PV), relative vorticity, and eddy-mean flow interaction, to the Kuroshio path change is discussed. Kuroshio path south of Japan includes the near-shore non-large meander (nNLM), the off-shore non-large meander (oNLM), and the typical large meander (tLM). Analyses reveal that the distribution of EKE, PV, relative vorticity, and energy exchange between the eddy field and the mean flow respectively varies with the Kuroshio path: (1) The tLM has the maximum EKE along the path; (2) The positive and negative PV are located at the onshore and offshore side of Kuroshio axis, respevetively; (3) The distributions of anomalous relative voritcity of nNLM, oNLM, and tLM are consistent with sea surface height anomalies (SSHAs); (4) The tLM has the largest energy exchange between the eddy field and the mean flow in terms of the rate of barotropic energy conversion. On the other hand, the stability analysis of ocean currents suggests that the three Kuroshio paths south of Japan have their own intrinsic properties of the instability.  相似文献   

Equatorward shift of the South Asian high in response to anthropogenic forcing   总被引：1，自引：0，他引：1  

Xia Qu  Gang Huang  Kaiming Hu  Shang-Ping Xie  Yan Du  Xiao-Tong Zheng  Lin Liu 《Theoretical and Applied Climatology》2015,119(1-2):113-122

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Relationship between summer rainfall anomalies and sub-seasonal oscillation intensity in the ChangJiang Valley in China     

《Dynamics of Atmospheres and Oceans》2015

Sub-seasonal variability of summer (May–October) rainfall over the ChangJiang Valley exhibits two dominant timescales, one with a quasi-biweekly (QBW) period (10–20 days) and the other with an intraseasonal oscillation (ISO) period (20–60 days). A significant positive correlation (at a 99% confidence level) was found between the summer precipitation anomaly and the intensity of the QBW and ISO modes in the region. By examining the composite structure and evolution characteristics, we note that the QBW mode is characterized by a northwest–southeast oriented wave train pattern, moving southeastward. The perturbations associated with the ISO mode propagate northwestward in strong ISO years but southeastward in weak ISO years. A marked feature is the phase leading of low-level moisture to convection in both the QBW and ISO mode. When the summer rainfall is strong in the ChangJiang Valley, large-scale atmospheric conditions in the strong QBW/ISO activity region are characterized by deeper moist layer, convectively more unstable stratification and greater ascending motion. Such mean conditions favor the growth of the QBW and ISO perturbations. Thus, a significant positive correlation between the summer precipitation and the strength of sub-seasonal variability arises from the large-scale control of the summer mean flow to perturbations.  相似文献   

Evaluating the economic damage of climate change on global coral reefs     

《Global Environmental Change》2015

This paper evaluates the global economic damage arising from the effects of climate change and associated carbon dioxide concentrations on the loss of coral reefs. We do this by first estimating the effects of sea surface temperature and carbon dioxide concentrations on coral cover. We develop a statistical relationship between coral coverage and sea surface temperature that indicates that the effects are dependent on the temperature range. For example, we find that increasing sea surface temperature causes coral coverage to decrease when sea surface temperature is higher than 26.85 °C, with the estimated reduction being 2.3% when sea surface temperature increases by 1%. In addition, we find that a 1% carbon dioxide increase induces a 0.6% reduction in global coral coverage. We also estimate the resultant loss in economic value based on a meta-analysis of the recreational and commercial value of reef coverage and a crude proportional approach for other value factors. The meta-analysis shows that the coral reef value decreases by 3.8% when coral cover falls by 1%. By combining these two steps we find that the lost value in terms of the global coral reef value under climate change scenarios ranges from US$3.95 to US$23.78 billion annually.  相似文献   

A delayed oscillator model for the quasi-periodic multidecadal variability of the NAO   总被引：1，自引：0，他引：1  

Cheng Sun  Jianping Li  Fei-Fei Jin 《Climate Dynamics》2015,45(7-8):2083-2099

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On Factors Controlling Air–Water Gas Exchange in a Large Tidal River     

David T. Ho  Peter Schlosser  Philip M. Orton 《Estuaries and Coasts》2011,34(6):1103-1116

Air–water gas exchange is an important process in aquatic systems, including tidal rivers and estuaries. While there are now reliable and routine methods for determining gas exchange over a range of temporal and spatial scales in the ocean and these measurements have resulted in widely used wind speed parameterizations to calculate air–sea gas exchange, the same has not been true for coastal inland waterways. Some studies have suggested that this difference is methodological, while others point to the existence of additional drivers for gas exchange besides wind in rivers and estuaries. Here, we present gas transfer velocities measured in the tidal Hudson River with a method widely used in oceanic studies, the ³He/SF₆ dual tracer technique. Airside and waterside forcings were determined with an anemometer and an acoustic Doppler current profiler, respectively. The results confirm that wind is the dominant driver of gas exchange in the tidal Hudson River, with negligible contribution from bottom-generated turbulence. Furthermore, a parameterization between wind speed and gas exchange developed for the ocean is able to predict gas exchange in this environment with high accuracy. It is hoped that by transferring methodology used in oceanic studies to rivers and estuaries, robust data can be obtained that will eventually allow development of widely applicable relationships between easily measured environmental variables and gas exchange in tidal inland waters.  相似文献   

A conceptual framework of groundwater flow in some crystalline aquifers in Southeastern Ghana     

Sandow Mark Yidana  Samuel Ganyaglo  Bruce Banoeng-Yakubo  Thomas Akabzaa 《Journal of African Earth Sciences》2011,59(2-3):185-194

A conceptual groundwater flow model was developed for the crystalline aquifers in southeastern part of the Eastern region, Ghana. The objective was to determine approximate levels of groundwater recharge, estimate aquifer hydraulic parameters, and then test various scenarios of groundwater extraction under the current conditions of recharge. A steady state groundwater flow model has been calibrated against measured water levels of 19 wells in the area. The resulting recharge is estimated to range from 8.97 × 10^?5 m/d to 7.14 × 10^?4 m/d resulting in a basin wide average recharge of about 9.6% of total annual precipitation, which results in a basin wide quantitative recharge of about 2.4 million m³/d in the area. This compares to recharge estimated from the chloride mass balance of 7.6% of precipitation determined in this study. The general groundwater flow in the area has also been determined to conform to the general northeast–southwest structural grain of the country. The implication is that the general hydrogeology is controlled by post genetic structural entities imposed on the rocks to create ingresses for sufficient groundwater storage and transport. Calibrated aquifer hydraulic conductivities range between 0.99 m/d and over 19.4 m/d. There is a significant contribution of groundwater discharge to stream flow in the study area. Increasing groundwater extraction will have an effect on stream flow. This study finds that the current groundwater extraction levels represent only 0.17% of the annual recharge from precipitation, and that groundwater can sustain future increased groundwater demands from population growth and industrialization.  相似文献