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Lian B.,Institute of Geochemistry Chinese Academy of science
Bulletin of Mineralogy Petrology and Geochemistry | Year: 2010

Carbonate rock weathering has received closely attention of scientists for a long time since the material origin of soils in Karst areas is still being disputed with no many agreements. Summarized previous studies about soil genesis from weathering of carbonate rocks as well as our own research progress we proposed that weathering of carbonate rock by rock microbe is an important way to form Karst soil. Microorganisms living in carbonate rocks need to uptake nutrients from the rock and to release complicated organic ligands into the rock, these processes will accelerate decomposition of the rocks; microorganisms can fix C and N from atmosphere and capture other exotic matters, like rain water, aerosol, dust and even soil particles, to provide origin materials of soil. In other words, the rock microorganisms play an important and un-substitute role in the formation of Karst soil from carbonate rock weathering during the long history of geological evolution.

Bi W.,Urumqi Jinwei Map character Information and Science and Technology Co. | Liu Y.,Institute of Geochemistry Chinese Academy of science
Wutan Huatan Jisuan Jishu | Year: 2014

In order to easily model topography in field work, on the basis of predecessors' achievements, the arbitrary quadrilateral element grid was used in the finite element method (FEM), and the electromagnetic field of models were designed to bilinear variation within each quadrilateral element in our numeric modeling. We deduced the specific formula to calculate the unit coefficient matrix by Gaussian numerical integral and the expression of the auxiliary field when using arbitrary quadratic element. Model calculation shows that the mean square error between the simulation results with the analytical solution is less than 1 percent, and the results of terrain model is consistent with the one of other scholar's. Through modeling of two ramp terrain modes with different pitch, comparing and analyzing the effect of the apparent resistivity and the phase. Due to the use of arbitrary quadrilateral element grid, the difficulty of programing was reduced, forward modeling can be more easily adapt to the topography variation.

Liu Y.,Institute of Geochemistry Chinese Academy of science | Wang X.-B.,Chengdu University of Technology | Wang Y.,Institute of Geochemistry Chinese Academy of science
Applied Geophysics | Year: 2013

To effectively minimize the electromagnetic field response in the total field solution, we propose a numerical modeling method for the two-dimensional (2D) timedomain transient electromagnetic secondary field of the line source based on the DuFort-Frankel finite-difference method. In the proposed method, we included the treatment of the earth-air boundary conductivity, calculated the normalized partial derivative of the induced electromotive force (Emf), and determined the forward time step. By extending upward the earth-air interface to the air grid nodes and the zero-value boundary conditions, not only we have a method that is more efficient but also simpler than the total field solution. We computed and analyzed the homogeneous half-space model and the flat layered model with high precision-the maximum relative error is less than 0.01% between our method and the analytical method-and the solution speed is roughly three times faster than the total-field solution. Lastly, we used the model of a thin body embedded in a homogeneous half-space at different delay times to depict the downward and upward spreading characteristics of the induced eddy current, and the physical interaction processes between the electromagnetic field and the underground low-resistivity body. © 2013 Editorial Office of Applied Geophysics and Springer-Verlag Berlin Heidelberg.

Ma L.-G.,Institute of Geochemistry Chinese Academy of science | Ma L.-G.,University of Chinese Academy of Sciences | Xiao B.-H.,Institute of Geochemistry Chinese Academy of science
Bulletin of Mineralogy Petrology and Geochemistry | Year: 2011

Extraction and fractionation of different humic substances from soil samples are key processes in the comprehensive study of soil humic substances. This paper carefully reviewed worldwide advance in extraction and fractionation of soil humic substances. Under guidance of the reference method recommended by the International Humic Substance Society (IHSS) , this paper discussed the experiment conditions, for example, extractant, dosage, and extracting cycles, and evaluated two fractionation techniques we set up in the experiments. It is suggested that high performance size exclusive chromatography ( HPSEC) and ultrafiltration are two of the state-of-art analytical methods in fractionating and characterizing humic substances in natural soils, and that, once being combined, they can provide profound information to better understand the chemical attributes and the molecular structures of soil humic substances.

Agency: Cordis | Branch: FP7 | Program: CP-IP-SICA | Phase: ENV.2010.4.1.3-2 | Award Amount: 9.15M | Year: 2010

The overall goal of the proposed project is to develop a coordinated global observation system for mercury able to provide temporal and spatial distributions of mercury concentrations in ambient air and precipitation over land and over surface waters at different altitudes and latitudes around the world. This will then provide high quality data for the validation and application of regional and global scale atmospheric models, to give to governments, national and international organisations and stakeholders a firm basis for future policy development and implementation. Specific objectives of the proposed project are (a) to establish a Global Observation System for Mercury (GMOS) able to provide ambient concentrations and deposition fluxes of mercury species around the world, by combining observations from permanent ground-based stations, and from oceanographic and tropospheric measurement campaigns; (b) to validate regional and global scale atmospheric mercury modelling systems able to predict temporal variations and spatial distributions of atmospheric mercury entering to and re-emitted from terrestrial and aquatic receptors; (c) to evaluate and identify source-receptor relationships at country scale and their temporal trends for current and projected scenarios of mercury emissions from anthropogenic and natural sources; (d) to develop interoperable tools to allow the sharing of observational and models output data produced by GMOS. The overarching goal of GMOS is to support the achievement of goals set by the GEO / GEOSS, and specifically of the GEO Task HE-09-02d and contribute to the advancement of our scientific understanding in the nine Societal Benefit Areas (SBA) established in GEOSS. The proposed project will rely on the results and knowledge acquired in the framework of past EU projects (i.e., MAMCS, MOE, MERCYMS) and international programs (i.e., UNECE TF HTAP; UNEP F&T partnership area).

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